<table><tr><td>ACTRIS in situ aerosol, cloud and trace gas services</td><td>0.0</td><td>0.0</td><td>0.0</td><td>0.2</td><td>3.3</td><td>0.5</td></tr><tr><td>ACTRIS aerosol remote sensing data services</td><td>0.1</td><td>1.0</td><td>0.1</td><td>0.9</td><td>1.0</td><td>3.2</td></tr><tr><td>ACTRIS cloud remote sensing data services</td><td>0.4</td><td>0.0</td><td>0.0</td><td>1.0</td><td>1.0</td><td>0.0</td></tr><tr><td>ACTRIS trace gas remote sensing data</td><td>0.1</td><td>0.0</td><td>0.0</td><td>0.0</td><td>0.6</td><td>0.4</td></tr><tr><td>ACTRIS atmospheric simulation chamber data services</td><td>0.1</td><td>0.0</td><td>0.0</td><td>0.1</td><td>0.5</td><td>0.2</td></tr></table>
<table><tr><td>ACTRIS in situ aerosol, cloud and trace gas services</td><td>0.0</td><td>0.0</td><td>0.0</td><td>0.2</td><td>3.3</td><td>0.5</td></tr><tr><td>ACTRIS aerosol remote sensing data services</td><td>0.1</td><td>1.0</td><td>0.1</td><td>0.9</td><td>1.0</td><td>3.2</td></tr><tr><td>ACTRIS cloud remote sensing data services</td><td>0.4</td><td>0.0</td><td>0.0</td><td>1.0</td><td>1.0</td><td>0.0</td></tr><tr><td>ACTRIS trace gas remote sensing data</td><td>0.1</td><td>0.0</td><td>0.0</td><td>0.0</td><td>0.6</td><td>0.4</td></tr><tr><td>ACTRIS atmospheric simulation chamber data services</td><td>0.1</td><td>0.0</td><td>0.0</td><td>0.1</td><td>0.5</td><td>0.2</td></tr></table>
# 7 Basic criteria for the selection of the ACTRIS Data Centre

Applications to host the ACTRIS Data Centre shall be evaluated against a set of criteria covering:

* The level of commitment for long-term operation

* The capacity to provide the operational support and the services described in sections 3 and 4

* The availability of the necessary infrastructure and equipment

* The availability of human resources (no., expertise)

* The efficiency in providing operational support and the services

* The feasibility of the implementation plan (costs, resources, timeline)

* The feasibility of the operation plan (methodology, costs per service)

* The level of maturity

* Adequacy of the decision-making

* Risk management strategy

These criteria will be detailed in the associated call documents.

# 8 Obligations of the ACTRIS Data Centre

## 8.1 General obligations

The following general obligations shall apply to the ACTRIS Data Centre. The ACTRIS DC is obliged:

* To organize its activities in a cost-efficient way, timely, and with high quality,

* To actively participate in the governance and sustainable development of ACTRIS,

* To provide services to users, according to the access procedures, and data policy

* To provide operation support to NFs, according to identified needs, agreed schedules, and procedures,

* To implement efficient user interaction activities by:

* Organizing workshops, to interact with users,

* Collecting user feed-back,

* Maintaining CF and ACTRIS websites,

* To document its activities, data offered and accesses provided, key performance indicators, and finances, and provide this information to the HO,

* To contribute to minimize and assess the uncertainties related to data and data products, according to their role and in collaboration with each other.

## 8.2 Technical obligations

The ACTRIS Data Centre and its potential units are obliged to put in place and offer the specific operation support marked with * in this document, section 3 and section 4. Other operation support described in this document is not mandatory for the data centre, but recommended.
## 7 Basic criteria for the selection of the ACTRIS Data Centre

Applications to host the ACTRIS Data Centre shall be evaluated against a set of criteria covering:

* The level of commitment for long-term operation

* The capacity to provide the operational support and the services described in sections 3 and 4

* The availability of the necessary infrastructure and equipment

* The availability of human resources (no., expertise)

* The efficiency in providing operational support and the services

* The feasibility of the implementation plan (costs, resources, timeline)

* The feasibility of the operation plan (methodology, costs per service)

* The level of maturity

* Adequacy of the decision-making

* Risk management strategy

These criteria will be detailed in the associated call documents.

## 8 Obligations of the ACTRIS Data Centre

### 8.1 General obligations

The following general obligations shall apply to the ACTRIS Data Centre. The ACTRIS DC is obliged:

* To organize its activities in a cost-efficient way, timely, and with high quality,

* To actively participate in the governance and sustainable development of ACTRIS,

* To provide services to users, according to the access procedures, and data policy

* To provide operation support to NFs, according to identified needs, agreed schedules, and procedures,

* To implement efficient user interaction activities by:

* Organizing workshops, to interact with users,

* Collecting user feed-back,

* Maintaining CF and ACTRIS websites,

* To document its activities, data offered and accesses provided, key performance indicators, and finances, and provide this information to the HO,

* To contribute to minimize and assess the uncertainties related to data and data products, according to their role and in collaboration with each other.

### 8.2 Technical obligations

The ACTRIS Data Centre and its potential units are obliged to put in place and offer the specific operation support marked with * in this document, section 3 and section 4. Other operation support described in this document is not mandatory for the data centre, but recommended.
## 8.2.1 Obligations towards the ACTRIS National Facilities

Technical obligations of the ACTRIS Data Centre towards the ACTRIS National Facilities refer strictly to the data curation of data and measurements described in this concept document and in *Technical concepts and requirements for ACTRIS Observational Platforms*. New techniques / instrument types are only accepted as ACTRIS instruments after the approval of the RI Committee and after the development of the associated QA procedures by the relevant CF. The operation of other techniques at the NFs does not imply obligation for the ACTRIS Data Centre to provide services or support.

### 8.2.1.1 Guidelines, quality control of data and procedures

The ACTRIS Data Centre is responsible for the quality control procedures applied to ACTRIS data and shall offer access to the guidelines for ACTRIS measurements conducted at the NFs. A full overview of all variables is included in Annex I, together with their associated TC. TCs develop and perform instrument QA, the DC develops and performs QC of submitted data. The procedures and routines and criteria for acceptance is defined in collaboration with the TC and DC.

### 8.2.1.2 Assessment of performances

The ACTRIS Data Centre is mandated to assist the related NFs and TC in the quality control of the measurements and data, by:

* Ensuring access to level 0 to level 3 data products

* Ensuring traceability of level 0 to level 3 data products

* Organizing regular exercises to assess the quality and control of the data

* Providing feedback on QC procedures and outcome to the NF

These activities require direct involvement of both NFs and TCs, and NFs should participate in these activities according to the plan proposed by the ACTRIS Data Centre and agreed together with the ACTRIS Scientific Advisory Board (SAB).

### 8.2.1.3 Transfer of knowledge and training

In addition to the training organized for the implementation of guidelines, procedures, and tools developed in support of the quality control of the measurements, the DC will organize training sessions with NFs for data submissions, metadata inclusion, flagging of data, the use of tools and software for QC. NFs should participate in these activities according to the plan proposed by the ACTRIS Data Centre and agreed together with the ACTRIS Scientific Advisory Board (SAB).
## 8.2.1 Obligations towards the ACTRIS National Facilities

Technical obligations of the ACTRIS Data Centre towards the ACTRIS National Facilities refer strictly to the data curation of data and measurements described in this concept document and in *Technical concepts and requirements for ACTRIS Observational Platforms*. New techniques / instrument types are only accepted as ACTRIS instruments after the approval of the RI Committee and after the development of the associated QA procedures by the relevant CF. The operation of other techniques at the NFs does not imply obligation for the ACTRIS Data Centre to provide services or support.

### 8.2.1.1 Guidelines, quality control of data and procedures

The ACTRIS Data Centre is responsible for the quality control procedures applied to ACTRIS data and shall offer access to the guidelines for ACTRIS measurements conducted at the NFs. A full overview of all variables is included in Annex I, together with their associated TC. TCs develop and perform instrument QA, the DC develops and performs QC of submitted data. The procedures and routines and criteria for acceptance is defined in collaboration with the TC and DC.

### 8.2.1.2 Assessment of performances

The ACTRIS Data Centre is mandated to assist the related NFs and TC in the quality control of the measurements and data, by:

* Ensuring access to level 0 to level 3 data products

* Ensuring traceability of level 0 to level 3 data products

* Organizing regular exercises to assess the quality and control of the data

* Providing feedback on QC procedures and outcome to the NF

These activities require direct involvement of both NFs and TCs, and NFs should participate in these activities according to the plan proposed by the ACTRIS Data Centre and agreed together with the ACTRIS Scientific Advisory Board (SAB).

### 8.2.1.3 Transfer of knowledge and training

In addition to the training organized for the implementation of guidelines, procedures, and tools developed in support of the quality control of the measurements, the DC will organize training sessions with NFs for data submissions, metadata inclusion, flagging of data, the use of tools and software for QC. NFs should participate in these activities according to the plan proposed by the ACTRIS Data Centre and agreed together with the ACTRIS Scientific Advisory Board (SAB).
### 8.2.2 Obligations towards the ACTRIS Topical Centres

The general share of responsibilities between the topical centres and the ACTRIS Data Centre is described in detail in the TC concept documents. ACTRIS DC shall ensure the implementation of a structure for interlinks, interactions, and collaboration. A proposed structure of a data centre with distributed nodes are illustrated in the figure below. An ACTRIS Data Expert team involving representatives from the DC, TC and NF is required to ensure the interactions. The team should be directed by the data centre leader.

<figure><img src="image_9.png" /></figure>

Figure 4: Schematic diagram of a structure for a distributed data centre ensuring interlinks, interactions, and collaboration within the ACTRIS Data Centre with the TC and NF, and for the integration and harmonisation across the RI. A Data Expert team is required to ensure the interactions between potential units and TCs.

## 8.3 Evaluation of ACTRIS Data Centre activities

The ACTRIS Data Centre performance will be evaluated annually with respect to Key Performance Indicators (KPIs), taking into consideration the general and technical obligations that have been described within this document. In the case of Data Centre distributed amongst several nodes, there will be completed a KPI form for each data centre unit.
### 8.2.2 Obligations towards the ACTRIS Topical Centres

The general share of responsibilities between the topical centres and the ACTRIS Data Centre is described in detail in the TC concept documents. ACTRIS DC shall ensure the implementation of a structure for interlinks, interactions, and collaboration. A proposed structure of a data centre with distributed nodes are illustrated in the figure below. An ACTRIS Data Expert team involving representatives from the DC, TC and NF is required to ensure the interactions. The team should be directed by the data centre leader.

<figure><img src="image_10.png" /><figcaption>Figure 4: Schematic diagram of a structure for a distributed data centre ensuring interlinks, interactions, and collaboration within the ACTRIS Data Centre with the TC and NF, and for the integration and harmonisation across the RI. A Data Expert team is required to ensure the interactions between potential units and TCs.</figcaption></figure>

## 8.3 Evaluation of ACTRIS Data Centre activities

The ACTRIS Data Centre performance will be evaluated annually with respect to Key Performance Indicators (KPIs), taking into consideration the general and technical obligations that have been described within this document. In the case of Data Centre distributed amongst several nodes, there will be completed a KPI form for each data centre unit.
<table><thead><tr><th>Criteria</th><th>Indicator</th><th>Planned value</th><th>Achieved value</th><th>Percentage of achievement<sup>4</sup></th><th>Weight</th></tr></thead><tbody><tr><td colspan="6" style="background-color: #d9d9d9; text-align: center; font-weight: bold;">GENERAL SCORE</td></tr><tr><td rowspan="5">Usefulness for ACTRIS NFs</td><td colspan="4" style="text-align: center; font-weight: bold;">CRITERIA TOTAL SCORE</td><td rowspan="5" style="text-align: center; vertical-align: middle;">35%</td></tr><tr><td colspan="4">Online and accessible tools for the NFs 24/7</td></tr><tr><td colspan="4">Archiving of annual data from ACTRIS NFs compared to submitted data to the DC</td></tr><tr><td colspan="4">Response time by help and support desk</td></tr><tr><td colspan="4">Average score of satisfaction received from NFs<br>Including utility and timeliness of the activities for support</td></tr><tr><td rowspan="5">Usefulness for ACTRIS users</td><td colspan="4" style="text-align: center; font-weight: bold;">CRITERIA TOTAL SCORE</td><td rowspan="5" style="text-align: center; vertical-align: middle;">35%</td></tr><tr><td colspan="4">Online and accessible level 2 and level 3 data 24/7</td></tr><tr><td colspan="4">No. of annual level 2 data sets offered to external users</td></tr><tr><td colspan="4">Monitor if the documentation made available for the users are accessible findable and used.</td></tr><tr><td colspan="4">Average score of satisfaction received from ACTRIS users<br>Including utility and timeliness of the services performed</td></tr><tr><td rowspan="4">Impact on science &amp; Integrati</td><td colspan="4" style="text-align: center; font-weight: bold;">CRITERIA TOTAL SCORE</td><td rowspan="4" style="text-align: center; vertical-align: middle;">20%</td></tr><tr><td colspan="4">Download of level 2 from the ACTRIS data user interface</td></tr><tr><td colspan="4">Download of level 3 from the ACTRIS data user interface</td></tr><tr><td colspan="4">Machine-to-machine data delivery of annual level 2 data sets</td></tr><tr><td colspan="4" style="text-align: center; font-weight: bold;">CRITERIA TOTAL SCORE</td><td rowspan="2" style="text-align: center; vertical-align: middle;">10%</td></tr><tr><td colspan="4">No. of participations to ACTRIS committees and boards</td></tr></tbody></table>

<footnote n="4">⁴ With regard to the planned and approved values</footnote>
<table><thead><tr><th>Criteria</th><th>Indicator</th><th>Planned value</th><th>Achieved value</th><th>Percentage of achievement<sup>4</sup></th><th>Weight</th></tr></thead><tbody><tr><td colspan="6" style="background-color: #d9d9d9; text-align: center; font-weight: bold;">GENERAL SCORE</td></tr><tr><td rowspan="5">Usefulness for ACTRIS NFs</td><td colspan="4" style="text-align: center; font-weight: bold;">CRITERIA TOTAL SCORE</td><td rowspan="5" style="text-align: center; vertical-align: middle;">35%</td></tr><tr><td colspan="4">Online and accessible tools for the NFs 24/7</td></tr><tr><td colspan="4">Archiving of annual data from ACTRIS NFs compared to submitted data to the DC</td></tr><tr><td colspan="4">Response time by help and support desk</td></tr><tr><td colspan="4">Average score of satisfaction received from NFs<br>Including utility and timeliness of the activities for support</td></tr><tr><td rowspan="5">Usefulness for ACTRIS users</td><td colspan="4" style="text-align: center; font-weight: bold;">CRITERIA TOTAL SCORE</td><td rowspan="5" style="text-align: center; vertical-align: middle;">35%</td></tr><tr><td colspan="4">Online and accessible level 2 and level 3 data 24/7</td></tr><tr><td colspan="4">No. of annual level 2 data sets offered to external users</td></tr><tr><td colspan="4">Monitor if the documentation made available for the users are accessible findable and used.</td></tr><tr><td colspan="4">Average score of satisfaction received from ACTRIS users<br>Including utility and timeliness of the services performed</td></tr><tr><td rowspan="4">Impact on science &amp; Integrati</td><td colspan="4" style="text-align: center; font-weight: bold;">CRITERIA TOTAL SCORE</td><td rowspan="4" style="text-align: center; vertical-align: middle;">20%</td></tr><tr><td colspan="4">Download of level 2 from the ACTRIS data user interface</td></tr><tr><td colspan="4">Download of level 3 from the ACTRIS data user interface</td></tr><tr><td colspan="4">Machine-to-machine data delivery of annual level 2 data sets</td></tr><tr><td colspan="4" style="text-align: center; font-weight: bold;">CRITERIA TOTAL SCORE</td><td rowspan="2" style="text-align: center; vertical-align: middle;">10%</td></tr><tr><td colspan="4">No. of participations to ACTRIS committees and boards</td></tr></tbody></table>

<footnote n="4">⁴ With regard to the planned and approved values</footnote>
<table><tr><td>No. of activities performed in collaboration with other TCs (joint SOPs, joint workshops, etc.)</td><td></td><td></td><td></td></tr><tr><td>Average score of satisfaction received from ACTRIS TC for the contribution to documentation and access to data products and tools</td><td></td><td></td><td></td></tr><tr><td>Average score of satisfaction received from ACTRIS HO for the quality and readiness of the reports</td><td></td><td></td><td></td></tr></table>
Section 2 - ACTRIS Data Centre

<table><tr><td>No. of activities performed in collaboration with other TCs (joint SOPs, joint workshops, etc.)</td><td></td><td></td><td></td></tr><tr><td>Average score of satisfaction received from ACTRIS TC for the contribution to documentation and access to data products and tools</td><td></td><td></td><td></td></tr><tr><td>Average score of satisfaction received from ACTRIS HO for the quality and readiness of the reports</td><td></td><td></td><td></td></tr></table>
Glossary

**ACTRIS data** - are the ACTRIS variables resulting from measurements that fully comply with the standard operating procedures (SOP), measurement recommendations, and quality guidelines established within ACTRIS.

o **ACTRIS level 0 data:** Raw sensor output, either mV or physical units. Native resolution, metadata necessary for next level.

o **ACTRIS level 1 data:** Calibrated and quality assured data with minimum level of quality control.

o **ACTRIS level 2 data:** Approved and fully quality controlled ACTRIS data product or geophysical variable.

o **ACTRIS level 3 data:** Elaborated ACTRIS data products derived by post-processing of ACTRIS Level 0 - 1 -2 data, and data from other sources. The data can be gridded or not.

o **ACTRIS synthesis product (Proper name to be defined later):** Data product from e.g. research activities, not under direct ACTRIS responsibility, but ACTRIS offer repository and access.

**ACTRIS Data Centre (DC)** - the Central Facility responsible for ACTRIS data curation, preservation, and distribution of data, value-added products and tools, and for hosting the ACTRIS data user interface.

**ACTRIS data originator** - entity operating instruments at a National Facility or Topical Centre, resulting in ACTRIS data and delivering ACTRIS data to the Data Centre.

**ACTRIS data provider** - the Data Centre offering ACTRIS data and value-added data products and tools to users.

**ACTRIS digital tools and services** - tailored codes and software for processing and visualization of ACTRIS data, production of ACTRIS data products, and for data analysis and research.

**ACTRIS exploratory platform** - National Facility (simulation chambers, laboratories, or mobile facilities) operating on a campaign basis and delivering dedicated data to the Data Centre.

**ACTRIS General Assembly (GA)** - the council of ministry- and funding organization representatives of ACTRIS members once the ACTRIS legal entity has been established, superior decision-making body of ACTRIS.

**ACTRIS Head Office (HO)** - a Central Facility coordinating and representing ACTRIS, and holding the statutory seat.

**ACTRIS label** - earmarks a data set or a measurement site as ACTRIS data or ACTRIS National Facility.

**ACTRIS observational platform** – ACTRIS National Facility performing long-term, regular observations and delivering standardized data to the Data Centre.

**ACTRIS Topical Centres (TCs)** – a Central Facility offering services and operation support for QA/QC of measurements and data (including training, calibration, QA/QC tools, and development of standard operation and evaluation procedures)
Glossary

**ACTRIS data** - are the ACTRIS variables resulting from measurements that fully comply with the standard operating procedures (SOP), measurement recommendations, and quality guidelines established within ACTRIS.

o **ACTRIS level 0 data:** Raw sensor output, either mV or physical units. Native resolution, metadata necessary for next level.

o **ACTRIS level 1 data:** Calibrated and quality assured data with minimum level of quality control.

o **ACTRIS level 2 data:** Approved and fully quality controlled ACTRIS data product or geophysical variable.

o **ACTRIS level 3 data:** Elaborated ACTRIS data products derived by post-processing of ACTRIS Level 0 - 1 -2 data, and data from other sources. The data can be gridded or not.

o **ACTRIS synthesis product (Proper name to be defined later):** Data product from e.g. research activities, not under direct ACTRIS responsibility, but ACTRIS offer repository and access.

**ACTRIS Data Centre (DC)** - the Central Facility responsible for ACTRIS data curation, preservation, and distribution of data, value-added products and tools, and for hosting the ACTRIS data user interface.

**ACTRIS data originator** - entity operating instruments at a National Facility or Topical Centre, resulting in ACTRIS data and delivering ACTRIS data to the Data Centre.

**ACTRIS data provider** - the Data Centre offering ACTRIS data and value-added data products and tools to users.

**ACTRIS digital tools and services** - tailored codes and software for processing and visualization of ACTRIS data, production of ACTRIS data products, and for data analysis and research.

**ACTRIS exploratory platform** - National Facility (simulation chambers, laboratories, or mobile facilities) operating on a campaign basis and delivering dedicated data to the Data Centre.

**ACTRIS General Assembly (GA)** - the council of ministry- and funding organization representatives of ACTRIS members once the ACTRIS legal entity has been established, superior decision-making body of ACTRIS.

**ACTRIS Head Office (HO)** - a Central Facility coordinating and representing ACTRIS, and holding the statutory seat.

**ACTRIS label** - earmarks a data set or a measurement site as ACTRIS data or ACTRIS National Facility.

**ACTRIS observational platform** - ACTRIS National Facility performing long-term, regular observations and delivering standardized data to the Data Centre.

**ACTRIS Topical Centres (TCs)** - a Central Facility offering services and operation support for QA/QC of measurements and data (including training, calibration, QA/QC tools, and development of standard operation and evaluation procedures)
**ACTRIS variables** - the measured atmospheric variables as described in the [ACTRIS Data Management Plan<fnref n="5" />].

**Central Facility (CF)** - a European level ACTRIS component that offers ACTRIS data or other ACTRIS services to users as well as operation support to ACTRIS National Facilities.

**Central Facility Unit** – part of a Central Facility located at, and operated by a research performing organization (RPO) or by ACTRIS ERIC.

**CF Director** – the person responsible for the coordination and representation of a Central Facility.

**CF Unit Head** – the person responsible for the coordination and representation of a Central Facility unit.

**CF Management Board** – consists of the CF Unit Heads and the CF Director; this board manages the Central Facility.

**Data curation** - the activity that stores, manages and ensures access to all persistent data sets produced within the infrastructure.

**Data traceability** - an unbroken chain of uniquely identified process steps leading from raw data to any kind of processed data, where identification of process steps follows the data.

**In situ measurements** - measured or sampled air and instrument are at the same location and in physical contact. In the context of ACTRIS, in situ measurements of aerosol, cloud, and reactive-trace-gas properties are performed at observational sites near the Earth surface, on mobile surface-based or airborne platforms, and in atmospheric simulation chambers and laboratories.

**Interim ACTRIS Council** - a council of ministry- and funding organization representatives of ACTRIS members before ACTRIS legal entity has been established (during the ACTRIS Preparation and Transition Phase), superior decision-making body of ACTRIS.

**Measurement traceability** - an unbroken chain of comparisons relating an instrument's measurements to a known standard, SI units in the ideal case.

**National Facility (NF)** - an observational or exploratory platform providing data and/or physical access to the platform within ACTRIS.

**Quality assurance and control:** Quality assurance is process oriented and focuses on defect prevention; quality control is product oriented and focuses on defect identification:

* **Quality Assurance (QA):** The process or set of processes used to ensure the quality of a product (e.g. data series, instrument, sample, measured value of a variable, etc.),

* **Quality Control (QC):** The process and activities of ensuring products and services meet the expectations.

**Remote sensing** - measured air and instrument are not at the same location and not in physical contact. In the context of ACTRIS, active and passive atmospheric remote-sensing techniques for the

<footnote n="5">⁵The ACTRIS data management plan and list of variables were approved by ACTRIS-2 scientific steering committee, October 2015. These documents are expected to be refined during ACTRIS-PPP (WP5).</footnote>
**ACTRIS variables** - the measured atmospheric variables as described in the [ACTRIS Data Management Plan<fnref n="5" />].

**Central Facility (CF)** - a European level ACTRIS component that offers ACTRIS data or other ACTRIS services to users as well as operation support to ACTRIS National Facilities.

**Central Facility Unit** – part of a Central Facility located at, and operated by a research performing organization (RPO) or by ACTRIS ERIC.

**CF Director** – the person responsible for the coordination and representation of a Central Facility.

**CF Unit Head** – the person responsible for the coordination and representation of a Central Facility unit.

**CF Management Board** – consists of the CF Unit Heads and the CF Director; this board manages the Central Facility.

**Data curation** - the activity that stores, manages and ensures access to all persistent data sets produced within the infrastructure.

**Data traceability** - an unbroken chain of uniquely identified process steps leading from raw data to any kind of processed data, where identification of process steps follows the data.

**In situ measurements** - measured or sampled air and instrument are at the same location and in physical contact. In the context of ACTRIS, in situ measurements of aerosol, cloud, and reactive-trace-gas properties are performed at observational sites near the Earth surface, on mobile surface-based or airborne platforms, and in atmospheric simulation chambers and laboratories.

**Interim ACTRIS Council** - a council of ministry- and funding organization representatives of ACTRIS members before ACTRIS legal entity has been established (during the ACTRIS Preparation and Transition Phase), superior decision-making body of ACTRIS.

**Measurement traceability** - an unbroken chain of comparisons relating an instrument's measurements to a known standard, SI units in the ideal case.

**National Facility (NF)** - an observational or exploratory platform providing data and/or physical access to the platform within ACTRIS.

**Quality assurance and control:** Quality assurance is process oriented and focuses on defect prevention; quality control is product oriented and focuses on defect identification:

* **Quality Assurance (QA):** The process or set of processes used to ensure the quality of a product (e.g. data series, instrument, sample, measured value of a variable, etc.),

* **Quality Control (QC):** The process and activities of ensuring products and services meet the expectations.

**Remote sensing** - measured air and instrument are not at the same location and not in physical contact. In the context of ACTRIS, active and passive atmospheric remote-sensing techniques for the

<footnote n="5">⁵The ACTRIS data management plan and list of variables were approved by ACTRIS-2 scientific steering committee, October 2015. These documents are expected to be refined during ACTRIS-PPP (WP5).</footnote>
observation of aerosols, clouds, and trace gases are applied at observational sites and on mobile surface-based or airborne platforms.

**RI committee** - consists of up to two representatives from each Central Facility and [three] representatives from the National Facilities Assembly; the RI committee supports the (Interim) Director or Board of Directors in operating the RI.

**Service and Access Management Unit (SAMU)** - a part of ACTRIS Head Office facilitating the access to ACTRIS services.

**User** - a person, a team, or an institution making use of ACTRIS data or other ACTRIS services, including access to ACTRIS facilities.

## Reference documents

- ACTRIS-PPP proposal

- ACTRIS Data Management Plan, approved by ACTRIS-2 SSC 23 October 2015

- ACTRIS Concept Documents

- ISO 10012:2003: Measurement management systems — Requirements for measurement processes and measuring equipment

- ISO 9000:2015: Quality management systems—Fundamentals and vocabulary
observation of aerosols, clouds, and trace gases are applied at observational sites and on mobile surface-based or airborne platforms.

**RI committee** - consists of up to two representatives from each Central Facility and [three] representatives from the National Facilities Assembly; the RI committee supports the (Interim) Director or Board of Directors in operating the RI.

**Service and Access Management Unit (SAMU)** - a part of ACTRIS Head Office facilitating the access to ACTRIS services.

**User** - a person, a team, or an institution making use of ACTRIS data or other ACTRIS services, including access to ACTRIS facilities.

## Reference documents

- ACTRIS-PPP proposal

- ACTRIS Data Management Plan, approved by ACTRIS-2 SSC 23 October 2015

- ACTRIS Concept Documents

- ISO 10012:2003: Measurement management systems — Requirements for measurement processes and measuring equipment

- ISO 9000:2015: Quality management systems—Fundamentals and vocabulary
Annex I: Catalogue with ACTRIS variables and detailed description

Full version of the file and detailed information for each variable is available from here until 1 March 2018:

https://folknilu.no/~richard/actris-ri-variables/Appendix I ACTRIS-RI_variables_21February2018.xlsx

<table><thead><tr><th>Annex I: Catalogue with ACTRIS L1-L2 data from observational NF</th><th>Colour codes for measurement techniques</th></tr></thead><tbody><tr><td></td><td>Variable produced from a single measurement technique</td></tr><tr><td></td><td>Variable produced from synergy of measurement techniques</td></tr><tr><td></td><td>Variable produced from synergy of measurement techniques where combinations are possible</td></tr></tbody></table>
Annex I: Catalogue with ACTRIS variables and detailed description

Full version of the file and detailed information for each variable is available from here until 1 March 2018:

https://folknilu.no/~richard/actris-ri-variables/Appendix I ACTRIS-RI_variables_21February2018.xlsx

<table><thead><tr><th>Annex I: Catalogue with ACTRIS L1-L2 data from observational NF</th><th>Colour codes for measurement techniques</th></tr></thead><tbody><tr><td></td><td>Variable produced from a single measurement technique</td></tr><tr><td></td><td>Variable produced from synergy of measurement techniques</td></tr><tr><td></td><td>Variable produced from synergy of measurement techniques where combinations are possible</td></tr></tbody></table>
<table><thead><tr><th>ACTRIS variable</th><th>NF requirements<br>Mandatory - M<br>Specializing - S<br>Optimum - O</th><th>Data level</th><th>Associated<br>Topical<br>Centre</th><th>Data<br>produce<br>r</th><th>RRT-O=<br>operational<br>in RRT now<br>RRT-S =<br>scheduled<br>from 2020</th><th>Time<br>resoluti<br>on</th><th>Integrating Nephelometer</th><th>Mobility Particle</th><th>Aerodynamic &amp; Optical Particle Size</th><th>Absorption Photometer</th><th>Condensation Particle</th><th>Scanning PSM, (N)AIS, N-MPSS</th><th>Particle Size Magnifier (PSM)</th><th>Cloud Condensation Nuclei Counter</th><th>Filter sampling</th><th>Thermal-optical analyser</th><th>Offline filter-based</th><th>Aerosol Mass Spectrometer</th><th>X-Ray Fluorescence, Particle Induced X-ray</th></tr></thead><tbody><tr><td colspan="21">Aerosol in situ</td></tr><tr><td>Particle light scattering and<br>backscattering coefficients</td><td>M</td><td>L0, L1, L2</td><td>CAIS</td><td>NF</td><td>NRT-O</td><td>1h</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Particle number size distribution -<br>mobility diameter</td><td>M</td><td>L0, L1, L2</td><td>CAIS</td><td>NF</td><td>NRT-O</td><td>1h</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Particle number size distribution -<br>optical and aerodynamic diameter</td><td>S</td><td>L0, L1, L2</td><td>CAIS</td><td>NF</td><td>NRT-S</td><td>1h</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Particle light absorption coefficient and<br>equivalent black carbon concentration</td><td>M</td><td>L0, L1, L2</td><td>CAIS</td><td>NF</td><td>NRT-O</td><td>1h</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Particle number concentration</td><td>S</td><td>L0, L1, L2</td><td>CAIS</td><td>NF</td><td>NRT-S</td><td>1h</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>

ACTRIS PPP (www.actris.eu) is supported by the European Commission under the Horizon 2020 - Research and Innovation Framework Programme, H2020-INFRADEV-2016-2017, Grant Agreement number: 739530
<table><thead><tr><th>ACTRIS variable</th><th>NF requirements<br>Mandatory - M<br>Specializing - S<br>Optimum - O</th><th>Data level</th><th>Associated<br>Topical<br>Centre</th><th>Data<br>produce<br>r</th><th>RRT-O=<br>operational<br>in RRT now<br>RRT-S =<br>scheduled<br>from 2020</th><th>Time<br>resoluti<br>on</th><th>Integrating Nephelometer</th><th>Mobility Particle</th><th>Aerodynamic &amp; Optical Particle Size</th><th>Absorption Photometer</th><th>Condensation Particle</th><th>Scanning PSM, (N)AIS, N-MPSS</th><th>Particle Size Magnifier (PSM)</th><th>Cloud Condensation Nuclei Counter</th><th>Filter sampling</th><th>Thermal-optical analyser</th><th>Offline filter-based</th><th>Aerosol Mass Spectrometer</th><th>X-Ray Fluorescence, Particle Induced X-ray</th></tr></thead><tbody><tr><td colspan="20">Aerosol in situ</td></tr><tr><td>Particle light scattering and<br>backscattering coefficients</td><td>M</td><td>L0, L1, L2</td><td>CAIS</td><td>NF</td><td>NRT-O</td><td>1h</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Particle number size distribution -<br>mobility diameter</td><td>M</td><td>L0, L1, L2</td><td>CAIS</td><td>NF</td><td>NRT-O</td><td>1h</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Particle number size distribution -<br>optical and aerodynamic diameter</td><td>S</td><td>L0, L1, L2</td><td>CAIS</td><td>NF</td><td>NRT-S</td><td>1h</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Particle light absorption coefficient and<br>equivalent black carbon concentration</td><td>M</td><td>L0, L1, L2</td><td>CAIS</td><td>NF</td><td>NRT-O</td><td>1h</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Particle number concentration</td><td>S</td><td>L0, L1, L2</td><td>CAIS</td><td>NF</td><td>NRT-S</td><td>1h</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>

ACTRIS PPP (www.actris.eu) is supported by the European Commission under the Horizon 2020 - Research and Innovation Framework Programme, H2020-INFRADEV-2016-2017, Grant Agreement number: 739530
<table><thead><tr><th>ACTRIS variable</th><th>NF requirements<br>Mandatory - M<br>Specializing - S<br>Optimum - O</th><th>Data level</th><th>Associated<br>Topical<br>Centre</th><th>Data<br>produce<br>r</th><th>RRT-O=<br>operational<br>in RRT now<br>RRT-S =<br>scheduled<br>from 2020</th><th>Time<br>resoluti<br>on</th><th>Integrating Nephelometer</th><th>Mobility Particle</th><th>Aerodynamic &amp; Optical Particle Size</th><th>Absorption Photometer</th><th>Condensation Particle</th><th>Scanning PSM, (N)AIS, N-MPSS</th><th>Particle Size Magnifier (PSM)</th><th>Cloud Condensation Nuclei Counter</th><th>Filter sampling</th><th>Thermal-optical analyser</th><th>Offline filter-based</th><th>Aerosol Mass Spectrometer</th><th>X-Ray Fluorescence, Particle Induced X-ray</th></tr></thead><tbody><tr><td colspan="20">Aerosol in situ</td></tr><tr><td>Nanoparticle number size distribution</td><td>S</td><td>L0, L1, L2</td><td>CAIS</td><td>NF</td><td>NRT-S</td><td>1h</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Nanoparticle number concentration</td><td>S</td><td>L0, L1, L2</td><td>CAIS</td><td>NF</td><td>NRT-S</td><td>1h</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Cloud condensation nuclei number<br>concentration</td><td>S</td><td>L0, L1, L2</td><td>CAIS</td><td>NF</td><td>NRT-S</td><td>1h</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Mass concentration of particulate<br>organic and elemental carbon</td><td>S</td><td>L2</td><td>CAIS</td><td>NF</td><td>-</td><td>&lt;48h -<br>2/week</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Mass concentration of particulate<br>organic tracers</td><td>S</td><td>L2</td><td>CAIS</td><td>NF</td><td>-</td><td>&lt;48h -<br>2/week</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>

ACTRIS PPP (www.actris.eu) is supported by the European Commission under the Horizon 2020 - Research and Innovation Framework Programme, H2020-INFRADEV-2016-2017, Grant Agreement number: 739530
<table><thead><tr><th>ACTRIS variable</th><th>NF requirements<br>Mandatory - M<br>Specializing - S<br>Optimum - O</th><th>Data level</th><th>Associated<br>Topical<br>Centre</th><th>Data<br>produce<br>r</th><th>RRT-O=<br>operational<br>in RRT now<br>RRT-S =<br>scheduled<br>from 2020</th><th>Time<br>resoluti<br>on</th><th>Integrating Nephelometer</th><th>Mobility Particle</th><th>Aerodynamic &amp; Optical Particle Size</th><th>Absorption Photometer</th><th>Condensation Particle</th><th>Scanning PSM, (N)AIS, N-MPSS</th><th>Particle Size Magnifier (PSM)</th><th>Cloud Condensation Nuclei Counter</th><th>Filter sampling</th><th>Thermal-optical analyser</th><th>Offline filter-based</th><th>Aerosol Mass Spectrometer</th><th>X-Ray Fluorescence, Particle Induced X-ray</th></tr></thead><tbody><tr><td colspan="20">Aerosol in situ</td></tr><tr><td>Nanoparticle number size distribution</td><td>S</td><td>L0, L1, L2</td><td>CAIS</td><td>NF</td><td>NRT-S</td><td>1h</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Nanoparticle number concentration</td><td>S</td><td>L0, L1, L2</td><td>CAIS</td><td>NF</td><td>NRT-S</td><td>1h</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Cloud condensation nuclei number<br>concentration</td><td>S</td><td>L0, L1, L2</td><td>CAIS</td><td>NF</td><td>NRT-S</td><td>1h</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Mass concentration of particulate<br>organic and elemental carbon</td><td>S</td><td>L2</td><td>CAIS</td><td>NF</td><td>-</td><td>&lt;48h -<br>2/week</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Mass concentration of particulate<br>organic tracers</td><td>S</td><td>L2</td><td>CAIS</td><td>NF</td><td>-</td><td>&lt;48h -<br>2/week</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>

ACTRIS PPP (www.actris.eu) is supported by the European Commission under the Horizon 2020 - Research and Innovation Framework Programme, H2020-INFRADEV-2016-2017, Grant Agreement number: 739530
<table><thead><tr><th>ACTRIS variable</th><th>NF requirements<br>Mandatory - M<br>Specializing - S<br>Optimum - O</th><th>Data level</th><th>Associated<br>Topical<br>Centre</th><th>Data<br>produce<br>r</th><th>RRT-O=<br>operational<br>in RRT now<br>RRT-S =<br>scheduled<br>from 2020</th><th>Time<br>resoluti<br>on</th><th>Integrating Nephelometer</th><th>Mobility Particle</th><th>Aerodynamic &amp; Optical Particle Size</th><th>Absorption Photometer</th><th>Condensation Particle</th><th>Scanning PSM, (N)AIS, N-MPSS</th><th>Particle Size Magnifier (PSM)</th><th>Cloud Condensation Nuclei Counter</th><th>Filter sampling</th><th>Thermal-optical analyser</th><th>Offline filter-based</th><th>Aerosol Mass Spectrometer</th><th>X-Ray Fluorescence, Particle Induced X-ray</th></tr></thead><tbody><tr><td colspan="20">Aerosol in situ</td></tr><tr><td>Mass concentration of non-refractory particulate organics and inorganics</td><td>S</td><td>L2</td><td>CAIS</td><td>NF/TC</td><td>NRT-S</td><td>1h</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Mass concentration of particulate elements</td><td>S</td><td>L1, L2</td><td>CAIS</td><td>NF</td><td>-</td><td>&lt;48h - 2/week</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>

ACTRIS PPP (www.actris.eu) is supported by the European Commission under the Horizon 2020 – Research and Innovation Framework Programme, H2020-INFRADEV-2016-2017, Grant Agreement number: 739530
<table><thead><tr><th>ACTRIS variable</th><th>NF requirements<br>Mandatory - M<br>Specializing - S<br>Optimum - O</th><th>Data level</th><th>Associated<br>Topical<br>Centre</th><th>Data<br>produce<br>r</th><th>RRT-O=<br>operational<br>in RRT now<br>RRT-S =<br>scheduled<br>from 2020</th><th>Time<br>resoluti<br>on</th><th>Integrating Nephelometer</th><th>Mobility Particle</th><th>Aerodynamic &amp; Optical Particle Size</th><th>Absorption Photometer</th><th>Condensation Particle</th><th>Scanning PSM, (N)AIS, N-MPSS</th><th>Particle Size Magnifier (PSM)</th><th>Cloud Condensation Nuclei Counter</th><th>Filter sampling</th><th>Thermal-optical analyser</th><th>Offline filter-based</th><th>Aerosol Mass Spectrometer</th><th>X-Ray Fluorescence, Particle Induced X-ray</th></tr></thead><tbody><tr><td colspan="20">Aerosol in situ</td></tr><tr><td>Mass concentration of non-refractory particulate organics and inorganics</td><td>S</td><td>L2</td><td>CAIS</td><td>NF/TC</td><td>NRT-S</td><td>1h</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Mass concentration of particulate elements</td><td>S</td><td>L1, L2</td><td>CAIS</td><td>NF</td><td>-</td><td>&lt;48h - 2/week</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>

ACTRIS PPP (www.actris.eu) is supported by the European Commission under the Horizon 2020 – Research and Innovation Framework Programme, H2020-INFRADEV-2016-2017, Grant Agreement number: 739530
<table><thead><tr><th>ACTRIS variable</th><th>NF requirements Mandatory - M Specializing - S Optimum - O</th><th>Data level</th><th>Associated Topical Centre</th><th>Data producer</th><th>RRT-O= operational in RRT now RRT-S = scheduled from 2020</th><th>Recommended time resolution</th><th>Mobility Particle Size Spectrometer</th><th>Condensation Particle Counter</th><th>Integrating Cloud Probe</th><th>Cloud Droplet Probe</th><th>Cloud Ice Probe</th><th>Aerosol Particle Sampler</th><th>Bulk collectors</th><th>INP instrument</th></tr></thead><tbody><tr><td colspan="16">Cloud in situ</td></tr><tr><td>Liquid Water Content</td><td>M</td><td>L0, L1, L2</td><td>CIS</td><td>NF</td><td>NRT-S</td><td>1 min</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Droplet effective diameter</td><td>M</td><td>L0, L1, L2</td><td>CIS</td><td>NF</td><td>NRT-S</td><td>1 min</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Droplet number concentration</td><td>S</td><td>L0, L1, L2</td><td>CIS</td><td>NF</td><td>NRT-S</td><td>1 min</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Droplet size distribution</td><td>S</td><td>L0, L1, L2</td><td>CIS</td><td>NF</td><td>NRT-S</td><td>1 min</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Interstitial aerosol number concentration</td><td>S</td><td>L0, L1, L2</td><td>CIS</td><td>NF</td><td>NRT-S</td><td>1 Min</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Interstitial aerosol size distribution</td><td>S</td><td>L0, L1, L2</td><td>CIS</td><td>NF</td><td>NRT-S</td><td>20 min</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Total aerosol number concentration</td><td>S</td><td>L0, L1, L2</td><td>CIS</td><td>NF</td><td>NRT-S</td><td>1 Min</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Total aerosol size distribution</td><td>S</td><td>L0, L1, L2</td><td>CIS</td><td>NF</td><td>NRT-S</td><td>20 min</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Cloud residuals number concentration</td><td>O</td><td>L0, L1, L2</td><td>CIS</td><td>NF</td><td>NRT-S</td><td>10 min</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>

ACTRIS PPP (www.actris.eu) is supported by the European Commission under the Horizon 2020 - Research and Innovation Framework Programme, H2020-INFRADEV-2016-2017, Grant Agreement number: 739530
<table><thead><tr><th>ACTRIS variable</th><th>NF requirements Mandatory - M Specializing - S Optimum - O</th><th>Data level</th><th>Associated Topical Centre</th><th>Data producer</th><th>RRT-O= operational in RRT now RRT-S = scheduled from 2020</th><th>Recommended time resolution</th><th>Mobility Particle Size Spectrometer</th><th>Condensation Particle Counter</th><th>Integrating Cloud Probe</th><th>Cloud Droplet Probe</th><th>Cloud Ice Probe</th><th>Aerosol Particle Sampler</th><th>Bulk collectors</th><th>INP instrument</th></tr></thead><tbody><tr><td colspan="16">Cloud in situ</td></tr><tr><td>Liquid Water Content</td><td>M</td><td>L0, L1, L2</td><td>CIS</td><td>NF</td><td>NRT-S</td><td>1 min</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Droplet effective diameter</td><td>M</td><td>L0, L1, L2</td><td>CIS</td><td>NF</td><td>NRT-S</td><td>1 min</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Droplet number concentration</td><td>S</td><td>L0, L1, L2</td><td>CIS</td><td>NF</td><td>NRT-S</td><td>1 min</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Droplet size distribution</td><td>S</td><td>L0, L1, L2</td><td>CIS</td><td>NF</td><td>NRT-S</td><td>1 min</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Interstitial aerosol number concentration</td><td>S</td><td>L0, L1, L2</td><td>CIS</td><td>NF</td><td>NRT-S</td><td>1 Min</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Interstitial aerosol size distribution</td><td>S</td><td>L0, L1, L2</td><td>CIS</td><td>NF</td><td>NRT-S</td><td>20 min</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Total aerosol number concentration</td><td>S</td><td>L0, L1, L2</td><td>CIS</td><td>NF</td><td>NRT-S</td><td>1 Min</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Total aerosol size distribution</td><td>S</td><td>L0, L1, L2</td><td>CIS</td><td>NF</td><td>NRT-S</td><td>20 min</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Cloud residuals number concentration</td><td>O</td><td>L0, L1, L2</td><td>CIS</td><td>NF</td><td>NRT-S</td><td>10 min</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>

ACTRIS PPP (www.actris.eu) is supported by the European Commission under the Horizon 2020 - Research and Innovation Framework Programme, H2020-INFRADEV-2016-2017, Grant Agreement number: 739530
<table><thead><tr><th>ACTRIS variable</th><th>NF requirements Mandatory - M Specializing - S Optimum - O</th><th>Data level</th><th>Associated Topical Centre</th><th>Data producer</th><th>RRT-O= operational in RRT now RRT-S = scheduled from 2020</th><th>Recommended time resolution</th><th>Mobility Particle Size Spectrometer</th><th>Condensation Particle Counter</th><th>Integrating Cloud Probe</th><th>Cloud Droplet Probe</th><th>Cloud Ice Probe</th><th>Aerosol Particle Sampler</th><th>Bulk collectors</th><th>INP instrument</th></tr></thead><tbody><tr><td colspan="16" style="background-color: #d9e2f3; font-weight: bold;">Cloud in situ</td></tr><tr><td>Cloud residuals composition</td><td>O</td><td>L1, L2</td><td>CIS</td><td>NF</td><td>NRT-S</td><td>1 h</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Ice particle number concentration</td><td>S</td><td>L0, L1, L2</td><td>CIS</td><td>NF</td><td>NRT-S</td><td>1 min</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Ice particle size distribution</td><td>S</td><td>L0, L1, L2</td><td>CIS</td><td>NF</td><td>NRT-S</td><td>10 min</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Ice nucleating particle number concentration</td><td>S</td><td>L0, L1, L2</td><td>CIS</td><td>NF</td><td>NRT-S</td><td>1 h</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Ice nucleating particle temperature spectrum</td><td>S</td><td>L1, L2</td><td>CIS</td><td>NF</td><td>NRT-S</td><td>&lt;= 24 h</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Bulk cloud water chemical composition</td><td>S</td><td>L1</td><td>CIS</td><td>NF</td><td>NRT-S</td><td>&lt;= 24 h</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>

ACTRIS PPP (www.actris.eu) is supported by the European Commission under the Horizon 2020 - Research and Innovation Framework Programme, H2020-INFRADEV-2016-2017, Grant Agreement number: 739530
<table><thead><tr><th>ACTRIS variable</th><th>NF requirements Mandatory - M Specializing - S Optimum - O</th><th>Data level</th><th>Associated Topical Centre</th><th>Data producer</th><th>RRT-O= operational in RRT now RRT-S = scheduled from 2020</th><th>Recommended time resolution</th><th>Mobility Particle Size Spectrometer</th><th>Condensation Particle Counter</th><th>Integrating Cloud Probe</th><th>Cloud Droplet Probe</th><th>Cloud Ice Probe</th><th>Aerosol Particle Sampler</th><th>Bulk collectors</th><th>INP instrument</th></tr></thead><tbody><tr><td colspan="16" style="background-color: #d9e2f3; font-weight: bold;">Cloud in situ</td></tr><tr><td>Cloud residuals composition</td><td>O</td><td>L1, L2</td><td>CIS</td><td>NF</td><td>NRT-S</td><td>1 h</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Ice particle number concentration</td><td>S</td><td>L0, L1, L2</td><td>CIS</td><td>NF</td><td>NRT-S</td><td>1 min</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Ice particle size distribution</td><td>S</td><td>L0, L1, L2</td><td>CIS</td><td>NF</td><td>NRT-S</td><td>10 min</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Ice nucleating particle number concentration</td><td>S</td><td>L0, L1, L2</td><td>CIS</td><td>NF</td><td>NRT-S</td><td>1 h</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Ice nucleating particle temperature spectrum</td><td>S</td><td>L1, L2</td><td>CIS</td><td>NF</td><td>NRT-S</td><td>&lt;= 24 h</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Bulk cloud water chemical composition</td><td>S</td><td>L1</td><td>CIS</td><td>NF</td><td>NRT-S</td><td>&lt;= 24 h</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>

ACTRIS PPP (www.actris.eu) is supported by the European Commission under the Horizon 2020 - Research and Innovation Framework Programme, H2020-INFRADEV-2016-2017, Grant Agreement number: 739530
<table><thead><tr><th>ACTRIS variable</th><th>NF requirements Mandatory - M Specializing - S Optimum - O</th><th>Data level</th><th>Associated Topical Centre</th><th>Data producer</th><th>RRT-O= operational in RRT now RRT-S = scheduled from 2020</th><th>Time resolution</th><th>On-line GC-FID</th><th>On-line GC-MS</th><th>On-line GC-FID/MS</th><th>On-line GC-Medusa</th><th>On-line PTR-MS</th><th>On-line Hantzsch</th><th>Off-line traps: ads-tubes</th><th>Off-line traps: DNPH-cartridge-HPLC</th><th>Off-line steel canister</th><th>Of-line glass flask</th><th>NO-O3 chemiluminescence</th><th>Potentially other measurement technique supported by the TC</th><th>Cavity Attenuated Phase Shift Spectroscopy (CAPS)</th><th>CI-API-TOF</th></tr></thead><tbody><tr><td colspan="20">Trace gases in situ</td></tr><tr><td>MHCs</td><td>M*, O</td><td>L0, L2</td><td>CGas-SiM</td><td>NF</td><td>NRT-S</td><td>1 h-2/week</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>OVOCs</td><td>M*, O</td><td>L0, L2</td><td>CGas-SiM</td><td>NF</td><td>NRT-S</td><td>4 h-2/week</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Terpenes</td><td>M*, O</td><td>L0, L2</td><td>CGas-SiM</td><td>NF</td><td>-</td><td>1 h-2/week</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>NO</td><td>M</td><td>L0, L1, L2</td><td>CGas-SiM</td><td>NF/TC</td><td>NRT-S</td><td>1h</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>NO2</td><td>M</td><td>L0, L1, L2</td><td>CGas-SiM</td><td>NF/TC</td><td>NRT-S</td><td>1h</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Condensable vapours</td><td>O*, S</td><td>L2</td><td>CGas-SiM</td><td>NF/TC</td><td>NRT-S</td><td>10 min</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>

ACTRIS PPP (www.actris.eu) is supported by the European Commission under the Horizon 2020 - Research and Innovation Framework Programme, H2020-INFRADEV-2016-2017, Grant Agreement number: 739530
<table><thead><tr><th>ACTRIS variable</th><th>NF requirements Mandatory - M Specializing - S Optimum - O</th><th>Data level</th><th>Associated Topical Centre</th><th>Data producer</th><th>RRT-O= operational in RRT now RRT-S = scheduled from 2020</th><th>Time resolution</th><th>On-line GC-FID</th><th>On-line GC-MS</th><th>On-line GC-FID/MS</th><th>On-line GC-Medusa</th><th>On-line PTR-MS</th><th>On-line Hantzsch</th><th>Off-line traps: ads-tubes</th><th>Off-line traps: DNPH-cartridge-HPLC</th><th>Off-line steel canister</th><th>Of-line glass flask</th><th>NO-O3 chemiluminescence</th><th>Potentially other measurement technique supported by the TC</th><th>Cavity Attenuated Phase Shift Spectroscopy (CAPS)</th><th>CI-API-TOF</th></tr></thead><tbody><tr><td colspan="20">Trace gases in situ</td></tr><tr><td>MHCs</td><td>M*, O</td><td>L0, L2</td><td>CGas-SiM</td><td>NF</td><td>NRT-S</td><td>1 h-2/week</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>OVOCs</td><td>M*, O</td><td>L0, L2</td><td>CGas-SiM</td><td>NF</td><td>NRT-S</td><td>4 h-2/week</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Terpenes</td><td>M*, O</td><td>L0, L2</td><td>CGas-SiM</td><td>NF</td><td>-</td><td>1 h-2/week</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>NO</td><td>M</td><td>L0, L1, L2</td><td>CGas-SiM</td><td>NF/TC</td><td>NRT-S</td><td>1h</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>NO2</td><td>M</td><td>L0, L1, L2</td><td>CGas-SiM</td><td>NF/TC</td><td>NRT-S</td><td>1h</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Condensable vapours</td><td>O*, S</td><td>L2</td><td>CGas-SiM</td><td>NF/TC</td><td>NRT-S</td><td>10 min</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>

ACTRIS PPP (www.actris.eu) is supported by the European Commission under the Horizon 2020 - Research and Innovation Framework Programme, H2020-INFRADEV-2016-2017, Grant Agreement number: 739530
<table><thead><tr><th>ACTRIS variable</th><th>NF requirements<br>Mandatory - M<br>Specializing - S<br>Optimum - O</th><th>Associated<br>Topical<br>Centre</th><th>Data<br>producer<br>L1, L2</th><th>RRT-O=<br>operational<br>in RRT now<br>RRT-S =<br>scheduled<br>from 2020</th><th>Time<br>resolution</th><th>Approx.<br>height<br>resolution</th><th>High-power aerosol LIDAR</th><th>Automatic sun/sky/lunar photometer</th><th>Automatic low-power aerosol LIDAR</th><th>Integrating Nephelometer</th><th>Mobility Particle<br>Size Spectrometer</th><th>Aerodynamic &amp; Optical Particle Size<br>Spectrometer</th></tr></thead><tbody><tr><td colspan="13" style="background-color: #d9e2f3; font-weight: bold;">Aerosol remote sensing</td></tr><tr><td>Attenuated backscatter profile</td><td>M</td><td>CARS</td><td>DC</td><td>NRT-S</td><td>1h, 5/week</td><td>60 m</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Volume depolarization profile</td><td>M</td><td>CARS</td><td>DC</td><td>NRT-S</td><td>1h, 5/week</td><td>60 m</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Particle backscatter coefficient profile</td><td>M</td><td>CARS</td><td>DC</td><td>NRT-S</td><td>1h, 5/week</td><td>60 m</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Particle extinction coefficient profile</td><td>M</td><td>CARS</td><td>DC</td><td>NRT-S</td><td>1h, 5/week</td><td>60 m</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Lidar ratio profile</td><td>M</td><td>CARS</td><td>DC</td><td>NRT-S</td><td>1h, 5/week</td><td>60 m</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Ångström exponent profile</td><td>O</td><td>CARS</td><td>DC</td><td>NRT-S</td><td>1h, 5/week</td><td>60 m</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Backscatter-related Ångström exponent profile</td><td>O</td><td>CARS</td><td>DC</td><td>NRT-S</td><td>1h, 5/week</td><td>60 m</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Particle depolarization ratio profile</td><td>M</td><td>CARS</td><td>DC</td><td>NRT-S</td><td>1h, 5/week</td><td>60 m</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Particle layer geometrical properties (height and thickness)</td><td>M</td><td>CARS</td><td>DC</td><td>NRT-S</td><td>1h, 5/week</td><td>60 m</td><td></td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>

ACTRIS PPP (www.actris.eu) is supported by the European Commission under the Horizon 2020 – Research and Innovation Framework Programme, H2020-INFRADEV-2016-2017, Grant Agreement number: 739530
<table><thead><tr><th>ACTRIS variable</th><th>NF requirements<br>Mandatory - M<br>Specializing - S<br>Optimum - O</th><th>Associated<br>Topical<br>Centre</th><th>Data<br>producer<br>L1, L2</th><th>RRT-O=<br>operational<br>in RRT now<br>RRT-S =<br>scheduled<br>from 2020</th><th>Time<br>resolution</th><th>Approx.<br>height<br>resolution</th><th>High-power aerosol LIDAR</th><th>Automatic sun/sky/lunar photometer</th><th>Automatic low-power aerosol LIDAR</th><th>Integrating Nephelometer</th><th>Mobility Particle<br>Size Spectrometer</th><th>Aerodynamic &amp; Optical Particle Size<br>Spectrometer</th></tr></thead><tbody><tr><td colspan="13" style="background-color: #d9e2f3; font-weight: bold;">Aerosol remote sensing</td></tr><tr><td>Attenuated backscatter profile</td><td>M</td><td>CARS</td><td>DC</td><td>NRT-S</td><td>1h, 5/week</td><td>60 m</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Volume depolarization profile</td><td>M</td><td>CARS</td><td>DC</td><td>NRT-S</td><td>1h, 5/week</td><td>60 m</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Particle backscatter coefficient profile</td><td>M</td><td>CARS</td><td>DC</td><td>NRT-S</td><td>1h, 5/week</td><td>60 m</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Particle extinction coefficient profile</td><td>M</td><td>CARS</td><td>DC</td><td>NRT-S</td><td>1h, 5/week</td><td>60 m</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Lidar ratio profile</td><td>M</td><td>CARS</td><td>DC</td><td>NRT-S</td><td>1h, 5/week</td><td>60 m</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Ångström exponent profile</td><td>O</td><td>CARS</td><td>DC</td><td>NRT-S</td><td>1h, 5/week</td><td>60 m</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Backscatter-related Ångström exponent profile</td><td>O</td><td>CARS</td><td>DC</td><td>NRT-S</td><td>1h, 5/week</td><td>60 m</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Particle depolarization ratio profile</td><td>M</td><td>CARS</td><td>DC</td><td>NRT-S</td><td>1h, 5/week</td><td>60 m</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Particle layer geometrical properties (height and thickness)</td><td>M</td><td>CARS</td><td>DC</td><td>NRT-S</td><td>1h, 5/week</td><td>60 m</td><td></td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>

ACTRIS PPP (www.actris.eu) is supported by the European Commission under the Horizon 2020 – Research and Innovation Framework Programme, H2020-INFRADEV-2016-2017, Grant Agreement number: 739530
<table><thead><tr><th>ACTRIS variable</th><th>NF requirements<br>Mandatory - M<br>Specializing - S<br>Optimum - O</th><th>Associated<br>Topical<br>Centre</th><th>Data<br>producer<br>L1, L2</th><th>RRT-O=<br>operational<br>in RRT now<br>RRT-S =<br>scheduled<br>from 2020</th><th>Time<br>resolution</th><th>Approx.<br>height<br>resolution</th><th>High-power aerosol LIDAR</th><th>Automatic sun/sky/lunar photometer</th><th>Automatic low-power aerosol LIDAR</th><th>Integrating Nephelometer</th><th>Mobility Particle<br>Size Spectrometer</th><th>Aerodynamic &amp; Optical Particle Size<br>Spectrometer</th></tr></thead><tbody><tr><td colspan="13" style="background-color: #ADD8E6; font-weight: bold;">Aerosol remote sensing</td></tr><tr><td>Particle layer optical properties: extinction, backscatter, LIDAR ratio, Ångström exponent, depolarization ratio, optical depth</td><td>M</td><td>CARS</td><td>DC</td><td>NRT-S</td><td>1h, 5/week</td><td>60 m</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Column integrated extinction</td><td>M</td><td>CARS</td><td>DC</td><td>NRT-S</td><td>1h, 5/week</td><td>60 m</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Planetary boundary layer height</td><td>O</td><td>CARS</td><td>DC</td><td>NRT-S</td><td>1h, 5/week</td><td>60 m</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Spectral Downward Sky Radiances</td><td>M</td><td>CARS</td><td>TC</td><td>NRT-O</td><td>1h</td><td>NA</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Direct Sun/Moon Extinction Aerosol Optical Depth (column)</td><td>M</td><td>CARS</td><td>TC</td><td>NRT-O</td><td>15min</td><td>NA</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Aerosol columnar properties</td><td>M</td><td>CARS</td><td>DC</td><td>NRT-S</td><td>1h</td><td>NA</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Aerosol profile microphysical and optical properties</td><td>M</td><td>CARS</td><td>DC</td><td>NRT-S</td><td>1h, 5/week</td><td>GARRLIC<br>Resolution</td><td></td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>

ACTRIS PPP (www.actris.eu) is supported by the European Commission under the Horizon 2020 – Research and Innovation Framework Programme, H2020-INFRADEV-2016-2017, Grant Agreement number: 739530
<table><thead><tr><th>ACTRIS variable</th><th>NF requirements<br>Mandatory - M<br>Specializing - S<br>Optimum - O</th><th>Associated<br>Topical<br>Centre</th><th>Data<br>producer<br>L1, L2</th><th>RRT-O=<br>operational<br>in RRT now<br>RRT-S =<br>scheduled<br>from 2020</th><th>Time<br>resolution</th><th>Approx.<br>height<br>resolution</th><th>High-power aerosol LIDAR</th><th>Automatic sun/sky/lunar photometer</th><th>Automatic low-power aerosol LIDAR</th><th>Integrating Nephelometer</th><th>Mobility Particle<br>Size Spectrometer</th><th>Aerodynamic &amp; Optical Particle Size<br>Spectrometer</th></tr></thead><tbody><tr><td colspan="13" style="background-color: #ADD8E6; font-weight: bold;">Aerosol remote sensing</td></tr><tr><td>Particle layer optical properties: extinction, backscatter, LIDAR ratio, Ångström exponent, depolarization ratio, optical depth</td><td>M</td><td>CARS</td><td>DC</td><td>NRT-S</td><td>1h, 5/week</td><td>60 m</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Column integrated extinction</td><td>M</td><td>CARS</td><td>DC</td><td>NRT-S</td><td>1h, 5/week</td><td>60 m</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Planetary boundary layer height</td><td>O</td><td>CARS</td><td>DC</td><td>NRT-S</td><td>1h, 5/week</td><td>60 m</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Spectral Downward Sky Radiances</td><td>M</td><td>CARS</td><td>TC</td><td>NRT-O</td><td>1h</td><td>NA</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Direct Sun/Moon Extinction Aerosol Optical Depth (column)</td><td>M</td><td>CARS</td><td>TC</td><td>NRT-O</td><td>15min</td><td>NA</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Aerosol columnar properties</td><td>M</td><td>CARS</td><td>DC</td><td>NRT-S</td><td>1h</td><td>NA</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Aerosol profile microphysical and optical properties</td><td>M</td><td>CARS</td><td>DC</td><td>NRT-S</td><td>1h, 5/week</td><td>GARRLIC<br>Resolution</td><td></td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>

ACTRIS PPP (www.actris.eu) is supported by the European Commission under the Horizon 2020 – Research and Innovation Framework Programme, H2020-INFRADEV-2016-2017, Grant Agreement number: 739530
<table><thead><tr><th>ACTRIS variable</th><th>NF requirements<br>Mandatory - M<br>Specializing - S<br>Optimum - O</th><th>Data level</th><th>Associate Topical Centre</th><th>Data producer</th><th>RRT-O= operational in RRT now RRT-S = scheduled from 2020</th><th>Recommended time resolution</th><th>Approx. height resolution for remote sensing data</th><th>Cloud radar</th><th>Doppler cloud radar</th><th>Lidar/ceilometer</th><th>Radiosonde</th><th>Microwave radiometer</th><th>Drop-counting raingauge</th><th>Disdrometer</th><th>NWP model input required</th></tr></thead><tbody><tr><td colspan="17">Cloud remote sensing</td></tr><tr><td>Cloud/aerosol target classification</td><td>M</td><td>L2</td><td>CCRES</td><td>DC</td><td>NRT-O</td><td>30s</td><td>60m</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Drizzle drop size distribution</td><td>M</td><td>L2</td><td>CCRES</td><td>DC</td><td>NRT-O</td><td>30s</td><td>60m</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Drizzle water content</td><td>M</td><td>L2</td><td>CCRES</td><td>DC</td><td>NRT-O</td><td>30s</td><td>60m</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Drizzle water flux</td><td>M</td><td>L2</td><td>CCRES</td><td>DC</td><td>NRT-O</td><td>30s</td><td>60m</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Ice water content</td><td>M</td><td>L2</td><td>CCRES</td><td>DC</td><td>NRT-O</td><td>30s</td><td>60m</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Liquid water content</td><td>M</td><td>L2</td><td>CCRES</td><td>DC</td><td>NRT-O</td><td>30s</td><td>60m</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Liquid water path</td><td>M</td><td>L1,L2</td><td>CCRES</td><td>DC</td><td>NRT-O</td><td>30s</td><td>-</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Temperature profile</td><td>O</td><td>L1,L2</td><td>CCRES</td><td>DC</td><td>NRT-O</td><td>30s</td><td>variable</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Relative humidity profile</td><td>O</td><td>L1,L2</td><td>CCRES</td><td>DC</td><td>NRT-O</td><td>30s</td><td>variable</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Integrated water vapour path</td><td>O</td><td>L1,L2</td><td>CCRES</td><td>DC</td><td>NRT-O</td><td>30s</td><td>-</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>

ACTRIS PPP (www.actris.eu) is supported by the European Commission under the Horizon 2020 - Research and Innovation Framework Programme, H2020-INFRADEV-2016-2017, Grant Agreement number: 739530
<table><thead><tr><th>ACTRIS variable</th><th>NF requirements<br>Mandatory - M<br>Specializing - S<br>Optimum - O</th><th>Data level</th><th>Associate Topical Centre</th><th>Data producer</th><th>RRT-O= operational in RRT now RRT-S = scheduled from 2020</th><th>Recommended time resolution</th><th>Approx. height resolution for remote sensing data</th><th>Cloud radar</th><th>Doppler cloud radar</th><th>Lidar/ceilometer</th><th>Radiosonde</th><th>Microwave radiometer</th><th>Drop-counting raingauge</th><th>Disdrometer</th><th>NWP model input required</th></tr></thead><tbody><tr><td colspan="16">Cloud remote sensing</td></tr><tr><td>Cloud/aerosol target classification</td><td>M</td><td>L2</td><td>CCRES</td><td>DC</td><td>NRT-O</td><td>30s</td><td>60m</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Drizzle drop size distribution</td><td>M</td><td>L2</td><td>CCRES</td><td>DC</td><td>NRT-O</td><td>30s</td><td>60m</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Drizzle water content</td><td>M</td><td>L2</td><td>CCRES</td><td>DC</td><td>NRT-O</td><td>30s</td><td>60m</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Drizzle water flux</td><td>M</td><td>L2</td><td>CCRES</td><td>DC</td><td>NRT-O</td><td>30s</td><td>60m</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Ice water content</td><td>M</td><td>L2</td><td>CCRES</td><td>DC</td><td>NRT-O</td><td>30s</td><td>60m</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Liquid water content</td><td>M</td><td>L2</td><td>CCRES</td><td>DC</td><td>NRT-O</td><td>30s</td><td>60m</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Liquid water path</td><td>M</td><td>L1,L2</td><td>CCRES</td><td>DC</td><td>NRT-O</td><td>30s</td><td>-</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Temperature profile</td><td>O</td><td>L1,L2</td><td>CCRES</td><td>DC</td><td>NRT-O</td><td>30s</td><td>variable</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Relative humidity profile</td><td>O</td><td>L1,L2</td><td>CCRES</td><td>DC</td><td>NRT-O</td><td>30s</td><td>variable</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Integrated water vapour path</td><td>O</td><td>L1,L2</td><td>CCRES</td><td>DC</td><td>NRT-O</td><td>30s</td><td>-</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>

ACTRIS PPP (www.actris.eu) is supported by the European Commission under the Horizon 2020 - Research and Innovation Framework Programme, H2020-INFRADEV-2016-2017, Grant Agreement number: 739530
<table><thead><tr><th>ACTRIS variable</th><th>NF requirements<br>Mandatory - M<br>Specializing - S<br>Optimum - O</th><th>Data level</th><th>Associated<br>Topical<br>Centre</th><th>Data<br>producer<br>L1, L2</th><th>RRT-O= operational in RRT<br>now<br>RRT-S = scheduled from<br>2020</th><th>FTIR</th><th>UVVIS - ZS</th><th>UVVIS- MAXDOAS</th></tr></thead><tbody><tr><td colspan="9">Trace gases remote sensing</td></tr><tr><td>Ozone partial columns</td><td></td><td>L2</td><td>RTGRSC</td><td></td><td>NRT-O</td><td></td><td></td><td></td></tr><tr><td>Ozone column</td><td></td><td>L2</td><td>RTGRSC</td><td></td><td>NRT-O</td><td></td><td></td><td></td></tr><tr><td>Formaldehyde column</td><td></td><td>L2</td><td>RTGRSC</td><td></td><td>NRT-O</td><td></td><td></td><td></td></tr><tr><td>Formaldehyde lower tropospheric profile</td><td></td><td>L2</td><td>RTGRSC</td><td></td><td>NRT-O</td><td></td><td></td><td></td></tr><tr><td>NO2 column</td><td>To be decided later</td><td>L2</td><td>RTGRSC</td><td>To be<br>decided<br>later</td><td>NRT-O</td><td></td><td></td><td></td></tr><tr><td>NO2 lower tropospheric profile</td><td></td><td>L2</td><td>RTGRSC</td><td></td><td>NRT-O</td><td></td><td></td><td></td></tr><tr><td>NH3 column</td><td></td><td>L2</td><td>RTGRSC</td><td></td><td>NRT-O</td><td></td><td></td><td></td></tr><tr><td>C2H6 column</td><td></td><td>L2</td><td>RTGRSC</td><td></td><td>NRT-O</td><td></td><td></td><td></td></tr><tr><td>SO2 lower tropospheric profile</td><td></td><td>L2</td><td>RTGRSC</td><td></td><td>NRT-O</td><td></td><td></td><td></td></tr><tr><td>SO2 column</td><td></td><td>L2</td><td>RTGRSC</td><td></td><td>NRT-O</td><td></td><td></td><td></td></tr></tbody></table>

ACTRIS PPP (www.actris.eu) is supported by the European Commission under the Horizon 2020 - Research and Innovation Framework Programme, H2020-INFRADEV-2016-2017, Grant Agreement number: 739530
<table><thead><tr><th>ACTRIS variable</th><th>NF requirements<br>Mandatory - M<br>Specializing - S<br>Optimum - O</th><th>Data level</th><th>Associated<br>Topical<br>Centre</th><th>Data<br>producer<br>L1, L2</th><th>RRT-O= operational in RRT<br>now<br>RRT-S = scheduled from<br>2020</th><th>FTIR</th><th>UVVIS - ZS</th><th>UVVIS- MAXDOAS</th></tr></thead><tbody><tr><td>Trace gases remote sensing</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Ozone partial columns</td><td></td><td>L2</td><td>RTGRSC</td><td></td><td>NRT-O</td><td></td><td></td><td></td></tr><tr><td>Ozone column</td><td></td><td>L2</td><td>RTGRSC</td><td></td><td>NRT-O</td><td></td><td></td><td></td></tr><tr><td>Formaldehyde column</td><td></td><td>L2</td><td>RTGRSC</td><td></td><td>NRT-O</td><td></td><td></td><td></td></tr><tr><td>Formaldehyde lower tropospheric profile</td><td></td><td>L2</td><td>RTGRSC</td><td></td><td>NRT-O</td><td></td><td></td><td></td></tr><tr><td>NO2 column</td><td>To be decided later</td><td>L2</td><td>RTGRSC</td><td>To be<br>decided<br>later</td><td>NRT-O</td><td></td><td></td><td></td></tr><tr><td>NO2 lower tropospheric profile</td><td></td><td>L2</td><td>RTGRSC</td><td></td><td>NRT-O</td><td></td><td></td><td></td></tr><tr><td>NH3 column</td><td></td><td>L2</td><td>RTGRSC</td><td></td><td>NRT-O</td><td></td><td></td><td></td></tr><tr><td>C2H6 column</td><td></td><td>L2</td><td>RTGRSC</td><td></td><td>NRT-O</td><td></td><td></td><td></td></tr><tr><td>SO2 lower tropospheric profile</td><td></td><td>L2</td><td>RTGRSC</td><td></td><td>NRT-O</td><td></td><td></td><td></td></tr><tr><td>SO2 column</td><td></td><td>L2</td><td>RTGRSC</td><td></td><td>NRT-O</td><td></td><td></td><td></td></tr></tbody></table>

ACTRIS PPP (www.actris.eu) is supported by the European Commission under the Horizon 2020 - Research and Innovation Framework Programme, H2020-INFRADEV-2016-2017, Grant Agreement number: 739530
Annex II: ACTRIS level 3 data products

Full version of the file and all detailed information for each level 3 product is available from here until 1 March 2018:

https://folknilu.no/~richard/actris-ri-variables/Appendix_II_ACTRIS-RI_level3_variables_21February2018.xlsx
Annex II: ACTRIS level 3 data products

Full version of the file and all detailed information for each level 3 product is available from here until 1 March 2018:

https://folknilu.no/~richard/actris-ri-variables/Appendix_II_ACTRIS-RI_level3_variables_21February2018.xlsx
<table><thead><tr><th>ACTRIS level 3 data product name</th><th>Expected user community<br>A= Academia<br>B=Business and industry<br>P= policy makers,<br>authorities, etc.</th><th>Aerosol/<br>Cloud/<br>Trace gas</th><th>Profile: P<br>Total column: C<br>Near surface: S</th><th>ACTRIS L0-L2<br>data: Obs<br>Model product - M<br>Earth observation - EO</th><th>Required external data and source</th><th>Status<br>O= operational<br>from 2020.<br>S= Support<br>required from<br>supporting projects</th></tr></thead><tbody><tr><td>Column Water Vapour Content</td><td>A</td><td>Trace gas</td><td>C</td><td>Obs</td><td>ACTRIS L1, AERONET</td><td>O</td></tr><tr><td>Climatology products for ACTRIS variables @ ACTRIS National Facilities across Europe</td><td>A, P</td><td>Aerosol/Trace gas</td><td>S, P</td><td>Obs</td><td>ACTRIS L2</td><td>S</td></tr><tr><td>Calculated Particle light scattering coefficients</td><td>A</td><td>aerosol</td><td>S</td><td>Obs</td><td>ACTRIS L2</td><td>O</td></tr><tr><td>Collocation service of data from contributing networks</td><td>A, P</td><td>aerosol</td><td>S</td><td>Obs</td><td>ACTRIS L2, EMEP</td><td>O</td></tr><tr><td>PM retrieval @GAW sites</td><td>A, P</td><td>aerosol</td><td>S</td><td>Obs</td><td>ACTRIS L2</td><td>S</td></tr><tr><td>Single Scattering Albedo @ACTRIS National Facilities</td><td>A, P</td><td>aerosol</td><td>S</td><td>Obs</td><td>ACTRIS L2</td><td>S</td></tr><tr><td>Calculated particle light extinction coefficient</td><td>A</td><td>aerosol</td><td>S</td><td>Obs</td><td>ACTRIS L2</td><td>S</td></tr><tr><td>Integrated full-range particle number size distribution</td><td>A</td><td>aerosol</td><td>S</td><td>Obs</td><td>ACTRIS L2</td><td>S</td></tr><tr><td>Source apportionment of submicron organic aerosols in Europe</td><td>A, P</td><td>Aerosol</td><td>S</td><td>Obs</td><td>ACTRIS L2</td><td>S</td></tr><tr><td>Volatile Organic Compounds (VOC) source attribution across Europe</td><td>A, P</td><td>Trace gas</td><td>S</td><td>Obs-M</td><td>ACTRIS L2</td><td>S</td></tr><tr><td>Cloud occurrence at cloud in situ observational platforms</td><td>A, P</td><td>Cloud</td><td>S</td><td>Obs</td><td>ACTRIS L2</td><td>O</td></tr><tr><td>Direct Sun/Moon Extinction Aerosol Optical Depth (column)</td><td>A</td><td>Aerosol</td><td>C</td><td>Obs</td><td>AERONET L1</td><td>O</td></tr><tr><td>Spectral Downward Sky Radiances</td><td>A</td><td>Aerosol</td><td>C</td><td>Obs</td><td>AERONET L1</td><td>O</td></tr><tr><td>Aerosol columnar properties</td><td>A</td><td>Aerosol</td><td>C</td><td>Obs</td><td>ACTRIS</td><td>S</td></tr><tr><td>ReOBS</td><td>A</td><td>Aerosol/<br>Cloud/<br>Trace gas</td><td>P, C, S</td><td>EO-Obs-M</td><td>ACTRIS L1, L2, AERONET,<br>METEOSAT</td><td>S</td></tr></tbody></table>

ACTRIS PPP (www.actris.eu) is supported by the European Commission under the Horizon 2020 - Research and Innovation Framework Programme, H2020-INFRADEV-2016-2017, Grant Agreement number: 739530
<table><thead><tr><th>ACTRIS level 3 data product name</th><th>Expected user community<br>A= Academia<br>B=Business and industry<br>P= policy makers,<br>authorities, etc.</th><th>Aerosol/<br>Cloud/<br>Trace gas</th><th>Profile: P<br>Total column: C<br>Near surface: S</th><th>ACTRIS L0-L2<br>data: Obs<br>Model product - M<br>Earth observation - EO</th><th>Required external data and source</th><th>Status<br>O= operational<br>from 2020.<br>S= Support<br>required from<br>supporting projects</th></tr></thead><tbody><tr><td>Column Water Vapour Content</td><td>A</td><td>Trace gas</td><td>C</td><td>Obs</td><td>ACTRIS L1, AERONET</td><td>O</td></tr><tr><td>Climatology products for ACTRIS variables @ ACTRIS National Facilities across Europe</td><td>A, P</td><td>Aerosol/Trace gas</td><td>S, P</td><td>Obs</td><td>ACTRIS L2</td><td>S</td></tr><tr><td>Calculated Particle light scattering coefficients</td><td>A</td><td>aerosol</td><td>S</td><td>Obs</td><td>ACTRIS L2</td><td>O</td></tr><tr><td>Collocation service of data from contributing networks</td><td>A, P</td><td>aerosol</td><td>S</td><td>Obs</td><td>ACTRIS L2, EMEP</td><td>O</td></tr><tr><td>PM retrieval @GAW sites</td><td>A, P</td><td>aerosol</td><td>S</td><td>Obs</td><td>ACTRIS L2</td><td>S</td></tr><tr><td>Single Scattering Albedo @ACTRIS National Facilities</td><td>A, P</td><td>aerosol</td><td>S</td><td>Obs</td><td>ACTRIS L2</td><td>S</td></tr><tr><td>Calculated particle light extinction coefficient</td><td>A</td><td>aerosol</td><td>S</td><td>Obs</td><td>ACTRIS L2</td><td>S</td></tr><tr><td>Integrated full-range particle number size distribution</td><td>A</td><td>aerosol</td><td>S</td><td>Obs</td><td>ACTRIS L2</td><td>S</td></tr><tr><td>Source apportionment of submicron organic aerosols in Europe</td><td>A, P</td><td>Aerosol</td><td>S</td><td>Obs</td><td>ACTRIS L2</td><td>S</td></tr><tr><td>Volatile Organic Compounds (VOC) source attribution across Europe</td><td>A, P</td><td>Trace gas</td><td>S</td><td>Obs-M</td><td>ACTRIS L2</td><td>S</td></tr><tr><td>Cloud occurrence at cloud in situ observational platforms</td><td>A, P</td><td>Cloud</td><td>S</td><td>Obs</td><td>ACTRIS L2</td><td>O</td></tr><tr><td>Direct Sun/Moon Extinction Aerosol Optical Depth (column)</td><td>A</td><td>Aerosol</td><td>C</td><td>Obs</td><td>AERONET L1</td><td>O</td></tr><tr><td>Spectral Downward Sky Radiances</td><td>A</td><td>Aerosol</td><td>C</td><td>Obs</td><td>AERONET L1</td><td>O</td></tr><tr><td>Aerosol columnar properties</td><td>A</td><td>Aerosol</td><td>C</td><td>Obs</td><td>ACTRIS</td><td>S</td></tr><tr><td>ReOBS</td><td>A</td><td>Aerosol/<br>Cloud/<br>Trace gas</td><td>P, C, S</td><td>EO-Obs-M</td><td>ACTRIS L1, L2, AERONET,<br>METEOSAT</td><td>S</td></tr></tbody></table>

ACTRIS PPP (www.actris.eu) is supported by the European Commission under the Horizon 2020 – Research and Innovation Framework Programme, H2020-INFRADEV-2016-2017, Grant Agreement number: 739530
<table><thead><tr><th>ACTRIS level 3 data product name</th><th>Expected user community<br>A= Academia<br>B=Business and industry<br>P= policy makers,<br>authorities, etc.</th><th>Aerosol/<br>Cloud/<br>Trace gas</th><th>Profile: P<br>Total column: C<br>Near surface: S</th><th>ACTRIS L0-L2<br>data: Obs<br>Model product - M<br>Earth observation - EO</th><th>Required external data and source</th><th>Status<br>O= operational<br>from 2020.<br>S= Support<br>required from<br>supporting projects</th></tr></thead><tbody><tr><td>Aerosol profile microphysical and optical properties</td><td>A</td><td>Aerosol</td><td>P</td><td>Obs</td><td>ACTRIS</td><td>S</td></tr><tr><td>Satellite data - combined with ground based ACTRIS data</td><td>A, P</td><td>Aerosol</td><td>P, C, S</td><td>EO-Obs</td><td>ACTRIS L2, MODIS, PARASOL,<br>CALIPSO, CloudSat, OMI, MISR,<br>Envisat/AATSR, IASI, MSG/SEVIRI</td><td>O</td></tr><tr><td colspan="7">ACTRIS data products involving regional and global models</td></tr><tr><td>Aerosol and Gas trend assessment</td><td>A, P</td><td>Aerosol/Trace gas</td><td>C, S</td><td>Obs-EO-M</td><td>ACTRIS L2,<br>/AERONET/AEROCOM/CAMS</td><td>O</td></tr><tr><td>Data Interpretation and Outlier Identification Tool</td><td>A, P</td><td>Aerosol/Trace gas</td><td>S</td><td>Obs-M</td><td>EBAS/CAMS</td><td>O</td></tr><tr><td>Optimal interpolation and Gap filling tool</td><td>A</td><td>aerosol</td><td>P, C, S</td><td>Obs-M</td><td>ACTRIS L2/AEROCOM</td><td>S</td></tr><tr><td>Model Evaluation Service</td><td>A</td><td>aerosol,<br>cloud</td><td>P, C, S</td><td>Obs-M</td><td>ACTRIS<br>L2/AERONET/AEROCOM/ICAP/SDS<br>WAS</td><td>O</td></tr><tr><td>NWP Model Evaluation Service</td><td>A</td><td>cloud</td><td>P, C, S</td><td>Obs-M</td><td>ACTRIS L2/NWP Models</td><td>O</td></tr><tr><td>Transport modelling products for assessment of source regions</td><td>A</td><td>Aerosol/Trace gas</td><td>P, C, S</td><td>M</td><td>ECMWF + FLEXPART</td><td>S</td></tr><tr><td>Alert Service for National Facilities</td><td>A</td><td>aerosol,<br>cloud</td><td>P, C, S</td><td>M</td><td>CAMS/SDSWAS/CAP</td><td>S</td></tr></tbody></table>

ACTRIS PPP (www.actris.eu) is supported by the European Commission under the Horizon 2020 - Research and Innovation Framework Programme, H2020-INFRADEV-2016-2017, Grant Agreement number: 739530
<table><thead><tr><th>ACTRIS level 3 data product name</th><th>Expected user community<br>A= Academia<br>B=Business and industry<br>P= policy makers,<br>authorities, etc.</th><th>Aerosol/<br>Cloud/<br>Trace gas</th><th>Profile: P<br>Total column: C<br>Near surface: S</th><th>ACTRIS L0-L2<br>data: Obs<br>Model product - M<br>Earth observation - EO</th><th>Required external data and source</th><th>Status<br>O= operational<br>from 2020.<br>S= Support<br>required from<br>supporting projects</th></tr></thead><tbody><tr><td>Aerosol profile microphysical and optical properties</td><td>A</td><td>Aerosol</td><td>P</td><td>Obs</td><td>ACTRIS</td><td>S</td></tr><tr><td>Satellite data - combined with ground based ACTRIS data</td><td>A, P</td><td>Aerosol</td><td>P, C, S</td><td>EO-Obs</td><td>ACTRIS L2, MODIS, PARASOL,<br>CALIPSO, CloudSat, OMI, MISR,<br>Envisat/AATSR, IASI, MSG/SEVIRI</td><td>O</td></tr><tr><td colspan="7">ACTRIS data products involving regional and global models</td></tr><tr><td>Aerosol and Gas trend assessment</td><td>A, P</td><td>Aerosol/Trace gas</td><td>C, S</td><td>Obs-EO-M</td><td>ACTRIS L2,<br>/AERONET/AEROCOM/CAMS</td><td>O</td></tr><tr><td>Data Interpretation and Outlier Identification Tool</td><td>A, P</td><td>Aerosol/Trace gas</td><td>S</td><td>Obs-M</td><td>EBAS/CAMS</td><td>O</td></tr><tr><td>Optimal interpolation and Gap filling tool</td><td>A</td><td>aerosol</td><td>P, C, S</td><td>Obs-M</td><td>ACTRIS L2/AEROCOM</td><td>S</td></tr><tr><td>Model Evaluation Service</td><td>A</td><td>aerosol,<br>cloud</td><td>P, C, S</td><td>Obs-M</td><td>ACTRIS<br>L2/AERONET/AEROCOM/ICAP/SDS<br>WAS</td><td>O</td></tr><tr><td>NWP Model Evaluation Service</td><td>A</td><td>cloud</td><td>P, C, S</td><td>Obs-M</td><td>ACTRIS L2/NWP Models</td><td>O</td></tr><tr><td>Transport modelling products for assessment of source regions</td><td>A</td><td>Aerosol/Trace gas</td><td>P, C, S</td><td>M</td><td>ECMWF + FLEXPART</td><td>S</td></tr><tr><td>Alert Service for National Facilities</td><td>A</td><td>aerosol,<br>cloud</td><td>P, C, S</td><td>M</td><td>CAMS/SDSWAS/CAP</td><td>S</td></tr></tbody></table>

ACTRIS PPP (www.actris.eu) is supported by the European Commission under the Horizon 2020 - Research and Innovation Framework Programme, H2020-INFRADEV-2016-2017, Grant Agreement number: 739530
## Annex III: ACTRIS workflow diagrams for data production

ACTRIS workflow diagrams depict the required interaction and distribution of work between NF - TC - DC as described in the Concepts of ACTRIS Central Facilities, and the description of NFs.

The diagrams will be available upon request to study the details.
## Annex III: ACTRIS workflow diagrams for data production

ACTRIS workflow diagrams depict the required interaction and distribution of work between NF - TC - DC as described in the Concepts of ACTRIS Central Facilities, and the description of NFs.

The diagrams will be available upon request to study the details.
Draft ACTRIS in situ aerosol, cloud and trace gas data workflow

The picture can be downloaded from here for details: https://folknilu.no/~richard/actris-ri-variables/
until 1 March

<figure><img src="image_10.png" /></figure>
Draft ACTRIS in situ aerosol, cloud and trace gas data workflow

The picture can be downloaded from here for details: https://folknilu.no/~richard/actris-ri-variables/
until 1 March

<figure><img src="image_11.png" /></figure>
# Draft ACTRIS aerosol remote sensing data workflow

The picture can be downloaded from here for details: https://folknilu.no/~richard/actris-ri-variables/
until 1 March

<figure><img src="image_11.png" /></figure>
Draft ACTRIS aerosol remote sensing data workflow

The picture can be downloaded from here for details: https://folknilu.no/~richard/actris-ri-variables/
until 1 March

<figure><img src="image_12.png" /></figure>
Draft ACTRIS cloud remote sensing data workflow

The picture can be downloaded from here for details: https://folknilu.no/~richard/actris-ri-variables/
until 1 March

<figure><img src="image_12.png" /></figure>
Draft ACTRIS cloud remote sensing data workflow

The picture can be downloaded from here for details: https://folknilu.no/~richard/actris-ri-variables/
until 1 March

<figure><img src="image_13.png" /></figure>
Draft ACTRIS atmospheric simulation chamber data workflow

The picture can be downloaded from here for details: https://folknilu.no/~richard/actris-ri-variables/
until 1 March

<figure><img src="image_13.png" /></figure>
Draft ACTRIS atmospheric simulation chamber data workflow

The picture can be downloaded from here for details: https://folknilu.no/~richard/actris-ri-variables/
until 1 March

<figure><img src="image_14.png" /></figure>
Section 3

Concept of the Centre for Aerosol In Situ
Measurements

ACTRIS PPP WP 4 Task 4.1

26.2.2018

Public
Section 3

Concept of the Centre for Aerosol In Situ
Measurements

ACTRIS PPP WP 4 Task 4.1

26.2.2018

Public
Contents

<table><tr><td>1</td><td>Purpose of the document</td><td>6</td></tr><tr><td>2</td><td>Description and role of the Centre for Aerosol In Situ Measurements</td><td>6</td></tr><tr><td>2.1</td><td>Framework</td><td>6</td></tr><tr><td>2.2</td><td>Scientific relevance</td><td>6</td></tr><tr><td>2.3</td><td>Mission</td><td>7</td></tr><tr><td>3</td><td>Operation support provided to ACTRIS National Facilities</td><td>7</td></tr><tr><td>3.1</td><td>Measurement techniques covered by the Centre for Aerosol In Situ Measurements, and related ACTRIS variables</td><td>8</td></tr><tr><td>3.1.1</td><td>Particle number size distribution - mobility diameter</td><td>8</td></tr><tr><td>3.1.2</td><td>Particle light scattering and backscattering coefficient</td><td>8</td></tr><tr><td>3.1.3</td><td>Particle light absorption coefficient and equivalent black carbon concentration</td><td>8</td></tr><tr><td>3.1.4</td><td>Mass concentration of particulate organic and elemental carbon</td><td>9</td></tr><tr><td>3.1.5</td><td>Particle number size distribution - optical and aerodynamic diameter</td><td>9</td></tr><tr><td>3.1.6</td><td>Particle number concentration</td><td>9</td></tr><tr><td>3.1.7</td><td>Mass concentration of particulate elements</td><td>10</td></tr><tr><td>3.1.8</td><td>Mass concentration of particulate organic tracers</td><td>10</td></tr><tr><td>3.1.9</td><td>Cloud condensation nuclei number concentration</td><td>11</td></tr><tr><td>3.1.10</td><td>Mass concentration of non-refractory particulate organics and inorganics</td><td>11</td></tr><tr><td>3.1.11</td><td>Nanoparticle number concentration</td><td>11</td></tr><tr><td>3.1.12</td><td>Nanoparticle number size distribution</td><td>12</td></tr><tr><td>3.2</td><td>Estimation of the need</td><td>13</td></tr><tr><td>3.3</td><td>Timeline for implementation of the mandatory operation support</td><td>14</td></tr><tr><td>3.4</td><td>Operation support for quality assurance and quality control</td><td>15</td></tr><tr><td>3.4.1</td><td>Definition and establishment of standard operation procedures</td><td>15</td></tr><tr><td>3.4.2</td><td>Definition of measurement quality-assurance criteria and procedures</td><td>18</td></tr><tr><td>3.4.3</td><td>Development and provision of instrument-specific calibration</td><td>21</td></tr><tr><td>3.4.4</td><td>Development and provision of in-house check-up tools</td><td>24</td></tr><tr><td>3.4.5</td><td>Development of data evaluation procedures and plausibility test</td><td>26</td></tr><tr><td>3.4.6</td><td>Realization of observational site performance audits with reference samples or mobile systems</td><td>28</td></tr><tr><td>3.4.7</td><td>Organization of regular exercises to assess the performances of the NFs, including instrument performance workshops</td><td>30</td></tr><tr><td>3.4.8</td><td>Contribution to documentation and traceability of level 0 to level 3 data products</td><td>31</td></tr><tr><td>3.4.9</td><td>Contribution to CEN, ISO, or similar standardization activities</td><td>33</td></tr><tr><td>3.5</td><td>Operation support for knowledge transfer and training</td><td>35</td></tr><tr><td>3.5.1</td><td>Training of operators and scientists</td><td>35</td></tr></table>
Contents

<table><tr><td>1</td><td>Purpose of the document</td><td>6</td></tr><tr><td>2</td><td>Description and role of the Centre for Aerosol In Situ Measurements</td><td>6</td></tr><tr><td>2.1</td><td>Framework</td><td>6</td></tr><tr><td>2.2</td><td>Scientific relevance</td><td>6</td></tr><tr><td>2.3</td><td>Mission</td><td>7</td></tr><tr><td>3</td><td>Operation support provided to ACTRIS National Facilities</td><td>7</td></tr><tr><td>3.1</td><td>Measurement techniques covered by the Centre for Aerosol In Situ Measurements, and related ACTRIS variables</td><td>8</td></tr><tr><td>3.1.1</td><td>Particle number size distribution - mobility diameter</td><td>8</td></tr><tr><td>3.1.2</td><td>Particle light scattering and backscattering coefficient</td><td>8</td></tr><tr><td>3.1.3</td><td>Particle light absorption coefficient and equivalent black carbon concentration</td><td>8</td></tr><tr><td>3.1.4</td><td>Mass concentration of particulate organic and elemental carbon</td><td>9</td></tr><tr><td>3.1.5</td><td>Particle number size distribution - optical and aerodynamic diameter</td><td>9</td></tr><tr><td>3.1.6</td><td>Particle number concentration</td><td>9</td></tr><tr><td>3.1.7</td><td>Mass concentration of particulate elements</td><td>10</td></tr><tr><td>3.1.8</td><td>Mass concentration of particulate organic tracers</td><td>10</td></tr><tr><td>3.1.9</td><td>Cloud condensation nuclei number concentration</td><td>11</td></tr><tr><td>3.1.10</td><td>Mass concentration of non-refractory particulate organics and inorganics</td><td>11</td></tr><tr><td>3.1.11</td><td>Nanoparticle number concentration</td><td>11</td></tr><tr><td>3.1.12</td><td>Nanoparticle number size distribution</td><td>12</td></tr><tr><td>3.2</td><td>Estimation of the need</td><td>13</td></tr><tr><td>3.3</td><td>Timeline for implementation of the mandatory operation support</td><td>14</td></tr><tr><td>3.4</td><td>Operation support for quality assurance and quality control</td><td>15</td></tr><tr><td>3.4.1</td><td>Definition and establishment of standard operation procedures</td><td>15</td></tr><tr><td>3.4.2</td><td>Definition of measurement quality-assurance criteria and procedures</td><td>18</td></tr><tr><td>3.4.3</td><td>Development and provision of instrument-specific calibration</td><td>21</td></tr><tr><td>3.4.4</td><td>Development and provision of in-house check-up tools</td><td>24</td></tr><tr><td>3.4.5</td><td>Development of data evaluation procedures and plausibility test</td><td>26</td></tr><tr><td>3.4.6</td><td>Realization of observational site performance audits with reference samples or mobile systems</td><td>28</td></tr><tr><td>3.4.7</td><td>Organization of regular exercises to assess the performances of the NFs, including instrument performance workshops</td><td>30</td></tr><tr><td>3.4.8</td><td>Contribution to documentation and traceability of level 0 to level 3 data products</td><td>31</td></tr><tr><td>3.4.9</td><td>Contribution to CEN, ISO, or similar standardization activities</td><td>33</td></tr><tr><td>3.5</td><td>Operation support for knowledge transfer and training</td><td>35</td></tr><tr><td>3.5.1</td><td>Training of operators and scientists</td><td>35</td></tr></table>
<table><tr><td>3.5.2</td><td>Consultancy for setting-up new observational or exploratory platforms and new instruments at the NFs</td><td>37</td></tr><tr><td>3.6</td><td>Operation support for improvement of measurement methodologies</td><td>39</td></tr><tr><td>3.6.1</td><td>Testing of new measurement instruments and procedures</td><td>39</td></tr><tr><td>3.6.2</td><td>Development of strategies to increase the duty cycle of instruments operated at the NFs, to reduce breakdown and maintenance downtime</td><td>41</td></tr><tr><td>3.6.3</td><td>Development of new technological products and methods</td><td>43</td></tr><tr><td>3.6.4</td><td>Development of retrieval algorithms or tools for producing level 1 to 3 data, including the exploitation of instrument synergies</td><td>45</td></tr><tr><td>4</td><td>Services provided to ACTRIS users</td><td>47</td></tr><tr><td>4.1</td><td>Estimation of the need</td><td>47</td></tr><tr><td>4.2</td><td>Provision of measurement quality assurance and quality control procedures and tools</td><td>47</td></tr><tr><td>4.2.1</td><td>Particle number size distribution – mobility diameter</td><td>47</td></tr><tr><td>4.2.2</td><td>Particle light scattering and backscattering coefficient</td><td>48</td></tr><tr><td>4.2.3</td><td>Particle light absorption coefficient and equivalent black carbon concentration</td><td>48</td></tr><tr><td>4.2.4</td><td>Mass concentration of particulate organic and elemental carbon</td><td>48</td></tr><tr><td>4.2.5</td><td>Particle number size distribution – optical and aerodynamic diameter</td><td>48</td></tr><tr><td>4.2.6</td><td>Particle number concentration</td><td>48</td></tr><tr><td>4.2.7</td><td>Mass concentration of particulate elements</td><td>48</td></tr><tr><td>4.2.8</td><td>Mass concentration of particulate organic tracers</td><td>48</td></tr><tr><td>4.2.9</td><td>Cloud condensation nuclei number concentration</td><td>48</td></tr><tr><td>4.2.10</td><td>Mass concentration of non-refractory particulate organics and inorganics</td><td>48</td></tr><tr><td>4.2.11</td><td>Nanoparticle number concentration</td><td>49</td></tr><tr><td>4.2.12</td><td>Nanoparticle number size distribution</td><td>49</td></tr><tr><td>4.3</td><td>Instrument-specific calibration</td><td>49</td></tr><tr><td>4.3.1</td><td>Particle number size distribution – mobility diameter</td><td>49</td></tr><tr><td>4.3.2</td><td>Particle light scattering and backscattering coefficient</td><td>49</td></tr><tr><td>4.3.3</td><td>Particle light absorption coefficient and equivalent black carbon concentration</td><td>49</td></tr><tr><td>4.3.4</td><td>Mass concentration of particulate organic and elemental carbon</td><td>49</td></tr><tr><td>4.3.5</td><td>Particle number size distribution – optical and aerodynamic diameter</td><td>49</td></tr><tr><td>4.3.6</td><td>Particle number concentration</td><td>49</td></tr><tr><td>4.3.7</td><td>Mass concentration of particulate elements</td><td>49</td></tr><tr><td>4.3.8</td><td>Mass concentration of particulate organic tracers</td><td>50</td></tr><tr><td>4.3.9</td><td>Cloud condensation nuclei number concentration</td><td>50</td></tr><tr><td>4.3.10</td><td>Mass concentration of non-refractory particulate organics and inorganics</td><td>50</td></tr><tr><td>4.3.11</td><td>Nanoparticle number concentration</td><td>50</td></tr><tr><td>4.3.12</td><td>Nanoparticle number size distribution</td><td>50</td></tr><tr><td>4.4</td><td>Knowledge transfer and operator training</td><td>50</td></tr><tr><td>4.4.1</td><td>Particle number size distribution – mobility diameter</td><td>50</td></tr><tr><td>4.4.2</td><td>Particle light scattering and backscattering coefficient</td><td>50</td></tr></table>
<table><tr><td>3.5.2</td><td>Consultancy for setting-up new observational or exploratory platforms and new instruments at the NFs</td><td>37</td></tr><tr><td>3.6</td><td>Operation support for improvement of measurement methodologies</td><td>39</td></tr><tr><td>3.6.1</td><td>Testing of new measurement instruments and procedures</td><td>39</td></tr><tr><td>3.6.2</td><td>Development of strategies to increase the duty cycle of instruments operated at the NFs, to reduce breakdown and maintenance downtime</td><td>41</td></tr><tr><td>3.6.3</td><td>Development of new technological products and methods</td><td>43</td></tr><tr><td>3.6.4</td><td>Development of retrieval algorithms or tools for producing level 1 to 3 data, including the exploitation of instrument synergies</td><td>45</td></tr><tr><td>4</td><td>Services provided to ACTRIS users</td><td>47</td></tr><tr><td>4.1</td><td>Estimation of the need</td><td>47</td></tr><tr><td>4.2</td><td>Provision of measurement quality assurance and quality control procedures and tools</td><td>47</td></tr><tr><td>4.2.1</td><td>Particle number size distribution – mobility diameter</td><td>47</td></tr><tr><td>4.2.2</td><td>Particle light scattering and backscattering coefficient</td><td>48</td></tr><tr><td>4.2.3</td><td>Particle light absorption coefficient and equivalent black carbon concentration</td><td>48</td></tr><tr><td>4.2.4</td><td>Mass concentration of particulate organic and elemental carbon</td><td>48</td></tr><tr><td>4.2.5</td><td>Particle number size distribution – optical and aerodynamic diameter</td><td>48</td></tr><tr><td>4.2.6</td><td>Particle number concentration</td><td>48</td></tr><tr><td>4.2.7</td><td>Mass concentration of particulate elements</td><td>48</td></tr><tr><td>4.2.8</td><td>Mass concentration of particulate organic tracers</td><td>48</td></tr><tr><td>4.2.9</td><td>Cloud condensation nuclei number concentration</td><td>48</td></tr><tr><td>4.2.10</td><td>Mass concentration of non-refractory particulate organics and inorganics</td><td>48</td></tr><tr><td>4.2.11</td><td>Nanoparticle number concentration</td><td>49</td></tr><tr><td>4.2.12</td><td>Nanoparticle number size distribution</td><td>49</td></tr><tr><td>4.3</td><td>Instrument-specific calibration</td><td>49</td></tr><tr><td>4.3.1</td><td>Particle number size distribution – mobility diameter</td><td>49</td></tr><tr><td>4.3.2</td><td>Particle light scattering and backscattering coefficient</td><td>49</td></tr><tr><td>4.3.3</td><td>Particle light absorption coefficient and equivalent black carbon concentration</td><td>49</td></tr><tr><td>4.3.4</td><td>Mass concentration of particulate organic and elemental carbon</td><td>49</td></tr><tr><td>4.3.5</td><td>Particle number size distribution – optical and aerodynamic diameter</td><td>49</td></tr><tr><td>4.3.6</td><td>Particle number concentration</td><td>49</td></tr><tr><td>4.3.7</td><td>Mass concentration of particulate elements</td><td>49</td></tr><tr><td>4.3.8</td><td>Mass concentration of particulate organic tracers</td><td>50</td></tr><tr><td>4.3.9</td><td>Cloud condensation nuclei number concentration</td><td>50</td></tr><tr><td>4.3.10</td><td>Mass concentration of non-refractory particulate organics and inorganics</td><td>50</td></tr><tr><td>4.3.11</td><td>Nanoparticle number concentration</td><td>50</td></tr><tr><td>4.3.12</td><td>Nanoparticle number size distribution</td><td>50</td></tr><tr><td>4.4</td><td>Knowledge transfer and operator training</td><td>50</td></tr><tr><td>4.4.1</td><td>Particle number size distribution – mobility diameter</td><td>50</td></tr><tr><td>4.4.2</td><td>Particle light scattering and backscattering coefficient</td><td>50</td></tr></table>
<table><tr><td>4.4.3</td><td>Particle light absorption coefficient and equivalent black carbon concentration</td><td>50</td></tr><tr><td>4.4.4</td><td>Mass concentration of particulate organic and elemental carbon</td><td>51</td></tr><tr><td>4.4.5</td><td>Particle number size distribution – optical and aerodynamic diameter</td><td>51</td></tr><tr><td>4.4.6</td><td>Particle number concentration</td><td>51</td></tr><tr><td>4.4.7</td><td>Mass concentration of particulate elements</td><td>51</td></tr><tr><td>4.4.8</td><td>Mass concentration of particulate organic tracers</td><td>51</td></tr><tr><td>4.4.9</td><td>Cloud condensation nuclei number concentration</td><td>51</td></tr><tr><td>4.4.10</td><td>Mass concentration of non-refractory particulate organics and inorganics</td><td>51</td></tr><tr><td>4.4.11</td><td>Nanoparticle number concentration</td><td>51</td></tr><tr><td>4.4.12</td><td>Nanoparticle number size distribution</td><td>51</td></tr><tr><td>4.5</td><td>Improvement of measurement and retrieval methodologies for aerosols, clouds, and reactive trace gases</td><td>52</td></tr><tr><td>4.5.1</td><td>Particle number size distribution - submicrometer</td><td>52</td></tr><tr><td>4.5.2</td><td>Particle light scattering and backscattering coefficient</td><td>52</td></tr><tr><td>4.5.3</td><td>Particle light absorption coefficient and equivalent black carbon concentration</td><td>52</td></tr><tr><td>4.5.4</td><td>Mass concentration of particulate organic and elemental carbon</td><td>52</td></tr><tr><td>4.5.5</td><td>Particle number size distribution – optical and aerodynamic diameter</td><td>52</td></tr><tr><td>4.5.6</td><td>Particle number concentration</td><td>52</td></tr><tr><td>4.5.7</td><td>Mass concentration of particulate elements</td><td>52</td></tr><tr><td>4.5.8</td><td>Mass concentration of particulate organic tracers</td><td>52</td></tr><tr><td>4.5.9</td><td>Cloud condensation nuclei number concentration</td><td>53</td></tr><tr><td>4.5.10</td><td>Mass concentration of non-refractory particulate organics and inorganics</td><td>53</td></tr><tr><td>4.5.11</td><td>Nanoparticle number concentration</td><td>53</td></tr><tr><td>4.5.12</td><td>Nanoparticle number size distribution</td><td>53</td></tr><tr><td>5</td><td>Governance and management structure of the Centre for Aerosol In Situ Measurements</td><td>53</td></tr><tr><td>6</td><td>Requirements for the Centre for Aerosol In Situ Measurements</td><td>54</td></tr><tr><td>6.1</td><td>General requirements</td><td>54</td></tr><tr><td>6.2</td><td>Technical requirements</td><td>54</td></tr><tr><td>6.2.1</td><td>Facilities</td><td>54</td></tr><tr><td>6.2.2</td><td>Human resources</td><td>57</td></tr><tr><td>6.2.3</td><td>Other requirements</td><td>58</td></tr><tr><td>7</td><td>Basic criteria for the selection of the Centre for Aerosol In Situ Measurements</td><td>59</td></tr><tr><td>8</td><td>Obligations of the Centre for Aerosol In Situ Measurements</td><td>60</td></tr><tr><td>8.1</td><td>General obligations</td><td>60</td></tr><tr><td>8.2</td><td>Technical obligations</td><td>60</td></tr><tr><td>8.2.1</td><td>Technical obligations in relation with the ACTRIS National Facilities</td><td>60</td></tr><tr><td>8.2.2</td><td>Technical obligations in relation with the ACTRIS Data Centre</td><td>62</td></tr></table>
<table><tr><td>4.4.3</td><td>Particle light absorption coefficient and equivalent black carbon concentration</td><td>50</td></tr><tr><td>4.4.4</td><td>Mass concentration of particulate organic and elemental carbon</td><td>51</td></tr><tr><td>4.4.5</td><td>Particle number size distribution – optical and aerodynamic diameter</td><td>51</td></tr><tr><td>4.4.6</td><td>Particle number concentration</td><td>51</td></tr><tr><td>4.4.7</td><td>Mass concentration of particulate elements</td><td>51</td></tr><tr><td>4.4.8</td><td>Mass concentration of particulate organic tracers</td><td>51</td></tr><tr><td>4.4.9</td><td>Cloud condensation nuclei number concentration</td><td>51</td></tr><tr><td>4.4.10</td><td>Mass concentration of non-refractory particulate organics and inorganics</td><td>51</td></tr><tr><td>4.4.11</td><td>Nanoparticle number concentration</td><td>51</td></tr><tr><td>4.4.12</td><td>Nanoparticle number size distribution</td><td>51</td></tr><tr><td>4.5</td><td>Improvement of measurement and retrieval methodologies for aerosols, clouds, and reactive trace gases</td><td>52</td></tr><tr><td>4.5.1</td><td>Particle number size distribution - submicrometer</td><td>52</td></tr><tr><td>4.5.2</td><td>Particle light scattering and backscattering coefficient</td><td>52</td></tr><tr><td>4.5.3</td><td>Particle light absorption coefficient and equivalent black carbon concentration</td><td>52</td></tr><tr><td>4.5.4</td><td>Mass concentration of particulate organic and elemental carbon</td><td>52</td></tr><tr><td>4.5.5</td><td>Particle number size distribution – optical and aerodynamic diameter</td><td>52</td></tr><tr><td>4.5.6</td><td>Particle number concentration</td><td>52</td></tr><tr><td>4.5.7</td><td>Mass concentration of particulate elements</td><td>52</td></tr><tr><td>4.5.8</td><td>Mass concentration of particulate organic tracers</td><td>52</td></tr><tr><td>4.5.9</td><td>Cloud condensation nuclei number concentration</td><td>53</td></tr><tr><td>4.5.10</td><td>Mass concentration of non-refractory particulate organics and inorganics</td><td>53</td></tr><tr><td>4.5.11</td><td>Nanoparticle number concentration</td><td>53</td></tr><tr><td>4.5.12</td><td>Nanoparticle number size distribution</td><td>53</td></tr><tr><td>5</td><td>Governance and management structure of the Centre for Aerosol In Situ Measurements</td><td>53</td></tr><tr><td>6</td><td>Requirements for the Centre for Aerosol In Situ Measurements</td><td>54</td></tr><tr><td>6.1</td><td>General requirements</td><td>54</td></tr><tr><td>6.2</td><td>Technical requirements</td><td>54</td></tr><tr><td>6.2.1</td><td>Facilities</td><td>54</td></tr><tr><td>6.2.2</td><td>Human resources</td><td>57</td></tr><tr><td>6.2.3</td><td>Other requirements</td><td>58</td></tr><tr><td>7</td><td>Basic criteria for the selection of the Centre for Aerosol In Situ Measurements</td><td>59</td></tr><tr><td>8</td><td>Obligations of the Centre for Aerosol In Situ Measurements</td><td>60</td></tr><tr><td>8.1</td><td>General obligations</td><td>60</td></tr><tr><td>8.2</td><td>Technical obligations</td><td>60</td></tr><tr><td>8.2.1</td><td>Technical obligations in relation with the ACTRIS National Facilities</td><td>60</td></tr><tr><td>8.2.2</td><td>Technical obligations in relation with the ACTRIS Data Centre</td><td>62</td></tr></table>
<table><tr><td>8.2.3</td><td>Technical obligations in relation with the Centre for Cloud In Situ Measurements and the Centre for Reactive Trace Gases In Situ Measurements</td><td>64</td></tr><tr><td>8.2.4</td><td>Technical obligations in relation with the ACTRIS users</td><td>64</td></tr><tr><td>8.3</td><td>Evaluation of the activity of the Centre for Aerosol In Situ Measurements</td><td>64</td></tr><tr><td>9</td><td>Glossary</td><td>66</td></tr><tr><td>10</td><td>Reference documents</td><td>69</td></tr><tr><td>11</td><td>Scientific references</td><td>70</td></tr><tr><td colspan="2">Annex: Provision of the operation support</td><td>71</td></tr><tr><td colspan="2">Scheduled support</td><td>71</td></tr><tr><td colspan="2">Operation support on request</td><td>72</td></tr></table>
<table><tr><td>8.2.3</td><td>Technical obligations in relation with the Centre for Cloud In Situ Measurements and the Centre for Reactive Trace Gases In Situ Measurements</td><td>64</td></tr><tr><td>8.2.4</td><td>Technical obligations in relation with the ACTRIS users</td><td>64</td></tr><tr><td>8.3</td><td>Evaluation of the activity of the Centre for Aerosol In Situ Measurements</td><td>64</td></tr><tr><td>9</td><td>Glossary</td><td>66</td></tr><tr><td>10</td><td>Reference documents</td><td>69</td></tr><tr><td>11</td><td>Scientific references</td><td>70</td></tr><tr><td colspan="2">Annex: Provision of the operation support</td><td>71</td></tr><tr><td colspan="2">Scheduled support</td><td>71</td></tr><tr><td colspan="2">Operation support on request</td><td>72</td></tr></table>
# 1 Purpose of the document

This document describes the relevance, mission, requirements and obligations of the ACTRIS Centre for
Aerosol In Situ Measurements.

# 2 Description and role of the Centre for Aerosol In Situ Measurements

## 2.1 Framework

ACTRIS is the European platform for fostering the use of research data and data analysis tools in the field of atmospheric aerosols, clouds, and reactive trace gases. ACTRIS Central Facilities (CFs) represent the key operative entities of this Research Infrastructure (RI) and have a fundamental role as they provide services to the users according to the ACTRIS access policy as well as operation support to the National Facilities (NFs). CFs are operated at the European level and are part of the governance and decision-making structure of the RI. Each CF may have several operational Units that can be located in the same or different locations, and are operated by research performing organizations (RPOs) or by ACTRIS ERIC. The CFs link the NFs, i.e. the observational and exploratory platforms, which are operated at the national level and produce the majority of the ACTRIS measurement data.

The Centre for Aerosol In Situ Measurements is one of the six ACTRIS Topical Centres (TCs) organized around the main scientific themes of ACTRIS: aerosols, clouds, and reactive trace gases, each with a particular focus on either remote sensing or in situ measurement techniques.

## 2.2 Scientific relevance

Aerosol particles play an important role in atmospheric physics and chemistry. They contribute not only health effects, but also influence directly radiative climate forcing and indirectly by acting as cloud or ice nuclei. They are thus involved into the hydrological cycle, supply nutrients to oceanic and terrestrial ecosystems, influence heterogeneous atmospheric chemistry, lead to adverse health effects, and reduce visibility. In contrast to trace gases, which have "a" concentration, aerosol particles have multi-dimensional properties. First, aerosol particles cover a size range from 0.001 µm to approximately 100 µm, making them subject to size-dependent aerosol microphysical processes. Aerosol particles of a certain size may also have different shapes, leading to different particle surface areas, which is important, for instance, for heterogeneous chemical processes. Moreover, particles of the same size can have different chemical composition, and compounds in the particle can either be liquid or solid. Not all of these dimension can be currently accounted for by appropriate measurement techniques, but the most relevant ones with respect to climate forcing and air quality shall be measured at the ACTRIS aerosol in situ NFs. These are currently (2018):

* Particle number size distribution – mobility diameter (0.01 - 0.8 µm)

* Particle light scattering and backscattering coefficient (multi-wavelengths)

* Particle light absorption coefficient and equivalent black carbon concentration
# 1 Purpose of the document

This document describes the relevance, mission, requirements and obligations of the ACTRIS Centre for
Aerosol In Situ Measurements.

# 2 Description and role of the Centre for Aerosol In Situ Measurements

## 2.1 Framework

ACTRIS is the European platform for fostering the use of research data and data analysis tools in the field of atmospheric aerosols, clouds, and reactive trace gases. ACTRIS Central Facilities (CFs) represent the key operative entities of this Research Infrastructure (RI) and have a fundamental role as they provide services to the users according to the ACTRIS access policy as well as operation support to the National Facilities (NFs). CFs are operated at the European level and are part of the governance and decision-making structure of the RI. Each CF may have several operational Units that can be located in the same or different locations, and are operated by research performing organizations (RPOs) or by ACTRIS ERIC. The CFs link the NFs, i.e. the observational and exploratory platforms, which are operated at the national level and produce the majority of the ACTRIS measurement data.

The Centre for Aerosol In Situ Measurements is one of the six ACTRIS Topical Centres (TCs) organized around the main scientific themes of ACTRIS: aerosols, clouds, and reactive trace gases, each with a particular focus on either remote sensing or in situ measurement techniques.

## 2.2 Scientific relevance

Aerosol particles play an important role in atmospheric physics and chemistry. They contribute not only health effects, but also influence directly radiative climate forcing and indirectly by acting as cloud or ice nuclei. They are thus involved into the hydrological cycle, supply nutrients to oceanic and terrestrial ecosystems, influence heterogeneous atmospheric chemistry, lead to adverse health effects, and reduce visibility. In contrast to trace gases, which have "a" concentration, aerosol particles have multi-dimensional properties. First, aerosol particles cover a size range from 0.001 µm to approximately 100 µm, making them subject to size-dependent aerosol microphysical processes. Aerosol particles of a certain size may also have different shapes, leading to different particle surface areas, which is important, for instance, for heterogeneous chemical processes. Moreover, particles of the same size can have different chemical composition, and compounds in the particle can either be liquid or solid. Not all of these dimension can be currently accounted for by appropriate measurement techniques, but the most relevant ones with respect to climate forcing and air quality shall be measured at the ACTRIS aerosol in situ NFs. These are currently (2018):

* Particle number size distribution – mobility diameter (0.01 - 0.8 µm)

* Particle light scattering and backscattering coefficient (multi-wavelengths)

* Particle light absorption coefficient and equivalent black carbon concentration
* Mass concentration of particulate organic and elemental carbon

* Particle number size distribution – optical and aerodynamic diameter (0.7 - 10 µm)

* Particle number concentration (> 0.01 µm)

* Mass concentration of particulate elements

* Mass concentration of particulate organic tracers

* Cloud condensation nuclei number concentration (at various supersaturations)

* Mass concentration of non-refractory particulate organics and inorganics

* Nanoparticle number concentration (< 0.01 µm)

* Nanoparticle number size distribution (0.001 - 0.02 µm)

Accordingly, operation support with respect to quality assurance and quality control (QA/QC) is needed for these variables in ACTRIS and this is described in this document.

The ACTRIS aerosol in situ observations already started to be established in the framework of the European projects CREATE (Construction, use and delivery of a European aerosol database, 2003 - 2005) and EUSAAR (European Supersites for Atmospheric Aerosol Research 2006 - 2011). In the ACTRIS-1 (2011 - 2015) and ACTRIS-2 (2015 - 2019) European projects this development was intensified, with a particular focus on harmonization, quality assurance and quality control. Now, in ACTRIS PPP (2017 - 2019) the definition and selection of aerosol in situ NFs and the respective TC shall be organized.

## 2.3 Mission

The mission of the Centre for Aerosol In Situ Measurements is to offer operation support to ACTRIS NFs operating instruments for the physical or chemical in situ characterization of atmospheric aerosol particles as well as for particle sampling and subsequent laboratory analysis of these particles.

Additionally, the Centre for Aerosol In Situ Measurements should offer specialized services for the above instruments and related ACTRIS variables, to ACTRIS users of various types: academia, business, industry, and public services.

## 3 Operation support provided to ACTRIS National Facilities

The operation support provided by the Centre for Aerosol In Situ Measurements comprises: a) procedures and tools for quality assurance and quality control of ACTRIS measurements and data, b) transfer of knowledge and training to ACTRIS operators, and c) improvements of measurement methodologies for aerosols, clouds, and reactive trace gases. The operation support is offered to the NFs for the measurement techniques described in this concept document, also listed in the *Technical concepts and requirements for ACTRIS Observational Platforms*.

The Centre for Aerosol In Situ Measurements is obliged to put in place and offer to NFs the specific operation support marked with * in this document. Other operation support described in this document is not mandatory for the TC, but recommended.
* Mass concentration of particulate organic and elemental carbon

* Particle number size distribution – optical and aerodynamic diameter (0.7 - 10 µm)

* Particle number concentration (> 0.01 µm)

* Mass concentration of particulate elements

* Mass concentration of particulate organic tracers

* Cloud condensation nuclei number concentration (at various supersaturations)

* Mass concentration of non-refractory particulate organics and inorganics

* Nanoparticle number concentration (< 0.01 µm)

* Nanoparticle number size distribution (0.001 - 0.02 µm)

Accordingly, operation support with respect to quality assurance and quality control (QA/QC) is needed for these variables in ACTRIS and this is described in this document.

The ACTRIS aerosol in situ observations already started to be established in the framework of the European projects CREATE (Construction, use and delivery of a European aerosol database, 2003 - 2005) and EUSAAR (European Supersites for Atmospheric Aerosol Research 2006 - 2011). In the ACTRIS-1 (2011 - 2015) and ACTRIS-2 (2015 - 2019) European projects this development was intensified, with a particular focus on harmonization, quality assurance and quality control. Now, in ACTRIS PPP (2017 - 2019) the definition and selection of aerosol in situ NFs and the respective TC shall be organized.

## 2.3 Mission

The mission of the Centre for Aerosol In Situ Measurements is to offer operation support to ACTRIS NFs operating instruments for the physical or chemical in situ characterization of atmospheric aerosol particles as well as for particle sampling and subsequent laboratory analysis of these particles.

Additionally, the Centre for Aerosol In Situ Measurements should offer specialized services for the above instruments and related ACTRIS variables, to ACTRIS users of various types: academia, business, industry, and public services.

## 3 Operation support provided to ACTRIS National Facilities

The operation support provided by the Centre for Aerosol In Situ Measurements comprises: a) procedures and tools for quality assurance and quality control of ACTRIS measurements and data, b) transfer of knowledge and training to ACTRIS operators, and c) improvements of measurement methodologies for aerosols, clouds, and reactive trace gases. The operation support is offered to the NFs for the measurement techniques described in this concept document, also listed in the *Technical concepts and requirements for ACTRIS Observational Platforms*.

The Centre for Aerosol In Situ Measurements is obliged to put in place and offer to NFs the specific operation support marked with * in this document. Other operation support described in this document is not mandatory for the TC, but recommended.
The operation support can be scheduled or on request. Participation at the scheduled activities is mandatory for the NFs. Measurements not following the mandatory actions are not considered as ACTRIS-conform and do not yield ACTRIS data.

In addition, NFs may request operation support which is not scheduled, depending on the identified need. Specific operation support offered as scheduled or offered on request is detailed in Annex: Provision of the operation support. This annex shall be updated each time is necessary (e.g. development of new testing or calibration methods and tools).

The Centre for Aerosol In Situ Measurements should operate at the state-of-the-art, fostering the implementation of validated new techniques in ACTRIS. To sustain a high level of performance and to stimulate the advancement of new techniques and methodologies, the Centre for Aerosol In Situ Measurements contributes to expert collaboration networks.

## 3.1 Measurement techniques covered by the Centre for Aerosol In Situ Measurements, and related ACTRIS variables

### 3.1.1 Particle number size distribution - mobility diameter

A mobility particle size spectrometer (MPSS) is used to measure the particle number size distribution of the sub-micrometre size range from approximately 0.01 to 0.8 µm. The technology is well established and is commercially available, but there are also custom designed measurement systems. A MPSS is robust and designed for long-term operations. However, it need regular checks on-site to quality-assure the measurement. The MPSS includes also a Condensation Particle Counter (CPC), which ideally has to undergo frequent on-site checks. This is done by a Round-Robin test with CPCs, which are sent from station to station. Additionally, annual or biannual calibrations of the entire MPSS and the CPC against a reference instruments are required. In case the MPSS instrument performance is not controlled, MPSS might drift with time causing unnoticed biases in both particle sizing and particle number concentration of up to several ten percent.

### 3.1.2 Particle light scattering and backscattering coefficient

Currently (2018), an integrating nephelometer is used to determine the particle light scattering and backscattering coefficient, usually for the PM₁₀ size range. The technology is well established and instruments are available from two manufacturers. Integrating nephelometers are robust and designed for long-term operations. Regular on-site gas calibrations are done with a frequency of at least once per three month to quality-assure the measurement. These calibrations are a common standard procedure already. Additionally, annual or biannual calibrations against a reference instrument are required. In case the nephelometer performance is not controlled, nephelometers might drift with time causing an unnoticed bias of up to several ten percent.

### 3.1.3 Particle light absorption coefficient and equivalent black carbon concentration

Generally, filter-based absorption photometers are used to determine the particle light absorption coefficient. The equivalent black carbon concentration mass concentration can be estimated from this.
The operation support can be scheduled or on request. Participation at the scheduled activities is mandatory for the NFs. Measurements not following the mandatory actions are not considered as ACTRIS-conform and do not yield ACTRIS data.

In addition, NFs may request operation support which is not scheduled, depending on the identified need. Specific operation support offered as scheduled or offered on request is detailed in Annex: Provision of the operation support. This annex shall be updated each time is necessary (e.g. development of new testing or calibration methods and tools).

The Centre for Aerosol In Situ Measurements should operate at the state-of-the-art, fostering the implementation of validated new techniques in ACTRIS. To sustain a high level of performance and to stimulate the advancement of new techniques and methodologies, the Centre for Aerosol In Situ Measurements contributes to expert collaboration networks.

## 3.1 Measurement techniques covered by the Centre for Aerosol In Situ Measurements, and related ACTRIS variables

### 3.1.1 Particle number size distribution - mobility diameter

A mobility particle size spectrometer (MPSS) is used to measure the particle number size distribution of the sub-micrometre size range from approximately 0.01 to 0.8 µm. The technology is well established and is commercially available, but there are also custom designed measurement systems. A MPSS is robust and designed for long-term operations. However, it need regular checks on-site to quality-assure the measurement. The MPSS includes also a Condensation Particle Counter (CPC), which ideally has to undergo frequent on-site checks. This is done by a Round-Robin test with CPCs, which are sent from station to station. Additionally, annual or biannual calibrations of the entire MPSS and the CPC against a reference instruments are required. In case the MPSS instrument performance is not controlled, MPSS might drift with time causing unnoticed biases in both particle sizing and particle number concentration of up to several ten percent.

### 3.1.2 Particle light scattering and backscattering coefficient

Currently (2018), an integrating nephelometer is used to determine the particle light scattering and backscattering coefficient, usually for the PM₁₀ size range. The technology is well established and instruments are available from two manufacturers. Integrating nephelometers are robust and designed for long-term operations. Regular on-site gas calibrations are done with a frequency of at least once per three month to quality-assure the measurement. These calibrations are a common standard procedure already. Additionally, annual or biannual calibrations against a reference instrument are required. In case the nephelometer performance is not controlled, nephelometers might drift with time causing an unnoticed bias of up to several ten percent.

### 3.1.3 Particle light absorption coefficient and equivalent black carbon concentration

Generally, filter-based absorption photometers are used to determine the particle light absorption coefficient. The equivalent black carbon concentration mass concentration can be estimated from this.
Usually for regional site, the measurements are done for the PM10 size range, while for urban station also PM1 can be required. The technology is well established and different instruments are available covering different number of wavelengths. Absorption photometer are robust and designed for long-term operations. However, they need regular checks to quality-assure the measurement, especially in terms of cleaning. Additionally, annual or biannual calibrations against a reference instrument are required. In case the absorption photometer performance is not controlled, absorption photometers might drift with time causing an unnoticed bias of up to several ten percent.

### 3.1.4 Mass concentration of particulate organic and elemental carbon

Particulate organic and elemental carbon concentrations are determined from the thermal-optical analysis on atmospheric particulate matter deposited on filters. Thermal-optical analysers actually determine the mass of total carbon deposited on the filter. Total carbon is split in OC and EC by measuring the aerosol deposit light transmittance during the thermal analytical process. The measurement of OC and EC deposited on filters is described in the European standards EN 16909. It states that OC and EC shall be determined using the thermal protocol EUSAAR-2 (Cavalli et al., 2010), also described in EN16909. This protocol is currently used by most research performing organisations in Europe. However, the 14 inter-laboratory comparisons organised across Europe show that various instruments lead to different determination of total carbon and OC or EC content in the same filter. Support is therefore needed to determine systematic error (bias) or random error (variability) in the determination of the total carbon, OC and EC variables. The errors generally observed are about 10% for total carbon and 25% for EC. Feedback provided to the beneficiaries by the TC can help reduce systematic biases. At least, bias and variability communicated to the beneficiaries can be clearly associated to the final data products.

### 3.1.5 Particle number size distribution – optical and aerodynamic diameter

For the upper accumulation and coarse more size ranges, optical and aerodynamic particle size spectrometers (OPSS and APSS) are employed. The technology of the APSS is well established and is commercially available from one manufacturer. The APSS is robust and designed for long-term operations. There is a different OPSS on the market, from which most could be used for long-term measurements. However, APSS and OPSS need regular checks on-site for sizing to quality-assure the measurement. Additionally, annual or biannual calibrations against a traceable standards and reference instruments are required. In case OPSS or APSS performance is not controlled, OPSS or APSS instruments might drift with time causing an unnoticed bias of up to several ten percent.

### 3.1.6 Particle number concentration

A condensation particle counter (CPC) is used to measure the particle number concentration for particle greater than 0.01 µm. The technology is well established and is commercially available from different manufacturers. The CPC is robust and designed for long-term operations. However, it needs regular checks on-site to quality-assure the measurement, especially in terms of cleaning the saturator and the optics. Additionally, annual calibrations of the CPC against a reference instrument are required. In case CPC performance, the counting efficiency, is not controlled, CPCs might drift with time causing an unnoticed bias of up to several ten percent.
Usually for regional site, the measurements are done for the PM10 size range, while for urban station also PM1 can be required. The technology is well established and different instruments are available covering different number of wavelengths. Absorption photometer are robust and designed for long-term operations. However, they need regular checks to quality-assure the measurement, especially in terms of cleaning. Additionally, annual or biannual calibrations against a reference instrument are required. In case the absorption photometer performance is not controlled, absorption photometers might drift with time causing an unnoticed bias of up to several ten percent.

### 3.1.4 Mass concentration of particulate organic and elemental carbon

Particulate organic and elemental carbon concentrations are determined from the thermal-optical analysis on atmospheric particulate matter deposited on filters. Thermal-optical analysers actually determine the mass of total carbon deposited on the filter. Total carbon is split in OC and EC by measuring the aerosol deposit light transmittance during the thermal analytical process. The measurement of OC and EC deposited on filters is described in the European standards EN 16909. It states that OC and EC shall be determined using the thermal protocol EUSAAR-2 (Cavalli et al., 2010), also described in EN16909. This protocol is currently used by most research performing organisations in Europe. However, the 14 inter-laboratory comparisons organised across Europe show that various instruments lead to different determination of total carbon and OC or EC content in the same filter. Support is therefore needed to determine systematic error (bias) or random error (variability) in the determination of the total carbon, OC and EC variables. The errors generally observed are about 10% for total carbon and 25% for EC. Feedback provided to the beneficiaries by the TC can help reduce systematic biases. At least, bias and variability communicated to the beneficiaries can be clearly associated to the final data products.

### 3.1.5 Particle number size distribution – optical and aerodynamic diameter

For the upper accumulation and coarse more size ranges, optical and aerodynamic particle size spectrometers (OPSS and APSS) are employed. The technology of the APSS is well established and is commercially available from one manufacturer. The APSS is robust and designed for long-term operations. There is a different OPSS on the market, from which most could be used for long-term measurements. However, APSS and OPSS need regular checks on-site for sizing to quality-assure the measurement. Additionally, annual or biannual calibrations against a traceable standards and reference instruments are required. In case OPSS or APSS performance is not controlled, OPSS or APSS instruments might drift with time causing an unnoticed bias of up to several ten percent.

### 3.1.6 Particle number concentration

A condensation particle counter (CPC) is used to measure the particle number concentration for particle greater than 0.01 µm. The technology is well established and is commercially available from different manufacturers. The CPC is robust and designed for long-term operations. However, it needs regular checks on-site to quality-assure the measurement, especially in terms of cleaning the saturator and the optics. Additionally, annual calibrations of the CPC against a reference instrument are required. In case CPC performance, the counting efficiency, is not controlled, CPCs might drift with time causing an unnoticed bias of up to several ten percent.
### 3.1.7 Mass concentration of particulate elements

Mass concentration of particulate elements and other elements are determined by several analytical techniques

* Particle Induced X-ray Emission (PIXE)

* Energy Dispersive X-Ray Fluorescence (ED-XRF)

* Inductively Coupled Plasma Mass Spectrometry (ICP-MS)

* Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES)

The quantification of particulate elements by these techniques depends on internal and/or external calibration. Trained practitioners are needed to produce high quality data that have passed various QA/QC measures. Previous inter-laboratory comparisons have shown that the various techniques can lead to different determination of aerosol elemental components in the same filter sample. Thus, feedback provided to the beneficiaries by the TC will reduce systematic biases. Audits in the form of inter-laboratory comparisons and Round-Robin tests with reference samples are needed to evaluate the performance of each single technique and/or experimental set-up.

### 3.1.8 Mass concentration of particulate organic tracers

Several analytical techniques are used to determine the Mass concentration of particulate organic tracers including:

* Liquid Chromatography Mass Spectrometry (LC/MS): (Ultra)- High-Performance Liquid Chromatography coupled to Hybrid Quadrupole-Orbitrap Mass Spectrometer (UHPLC/HRMS), High-Performance Liquid Chromatography Electrospray Ionization coupled to Time-of-Flight Mass Spectrometry (HPLC/ESI-TOFMS), Ultra-Performance Liquid Chromatography Electrospray Ionization coupled to Ion-Mobility Mass Spectrometer with a Time-of-Flight Mass Spectrometry (UPLC/ESI-IMS-QTOFMS)

* Gas Chromatography Mass spectrometry (GC/MS): Curie-Point-Pyrolysis Gas Chromatography with Mass Spectrometry (CPP-GCMS), standard GCMS applications with derivatisation procedures)

* Ion Chromatography Pulsed Amperometric Detection (IC/PAD)

The quantification of organic tracers by these techniques highly depends on internal and external calibration. Thus, well trained operators are needed to produce high quality data that has passed various QA/QC measures. Also audits in the form of inter-laboratory comparisons and Round-Robin test with reference compounds are needed to evaluate the performance of each single system.
### 3.1.7 Mass concentration of particulate elements

Mass concentration of particulate elements and other elements are determined by several analytical techniques

* Particle Induced X-ray Emission (PIXE)

* Energy Dispersive X-Ray Fluorescence (ED-XRF)

* Inductively Coupled Plasma Mass Spectrometry (ICP-MS)

* Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES)

The quantification of particulate elements by these techniques depends on internal and/or external calibration. Trained practitioners are needed to produce high quality data that have passed various QA/QC measures. Previous inter-laboratory comparisons have shown that the various techniques can lead to different determination of aerosol elemental components in the same filter sample. Thus, feedback provided to the beneficiaries by the TC will reduce systematic biases. Audits in the form of inter-laboratory comparisons and Round-Robin tests with reference samples are needed to evaluate the performance of each single technique and/or experimental set-up.

### 3.1.8 Mass concentration of particulate organic tracers

Several analytical techniques are used to determine the Mass concentration of particulate organic tracers including:

* Liquid Chromatography Mass Spectrometry (LC/MS): (Ultra)- High-Performance Liquid Chromatography coupled to Hybrid Quadrupole-Orbitrap Mass Spectrometer (UHPLC/HRMS), High-Performance Liquid Chromatography Electrospray Ionization coupled to Time-of-Flight Mass Spectrometry (HPLC/ESI-TOFMS), Ultra-Performance Liquid Chromatography Electrospray Ionization coupled to Ion-Mobility Mass Spectrometer with a Time-of-Flight Mass Spectrometry (UPLC/ESI-IMS-QTOFMS)

* Gas Chromatography Mass spectrometry (GC/MS): Curie-Point-Pyrolysis Gas Chromatography with Mass Spectrometry (CPP-GCMS), standard GCMS applications with derivatisation procedures)

* Ion Chromatography Pulsed Amperometric Detection (IC/PAD)

The quantification of organic tracers by these techniques highly depends on internal and external calibration. Thus, well trained operators are needed to produce high quality data that has passed various QA/QC measures. Also audits in the form of inter-laboratory comparisons and Round-Robin test with reference compounds are needed to evaluate the performance of each single system.
### 3.1.9 Cloud condensation nuclei number concentration

A cloud condensation nuclei counter (CCNC) is used to measure the Cloud condensation nuclei number concentration at different supersaturations and possibly as function of particle size. The technology is established and is commercially available from one manufacturers. The CCNC designed for long-term operations. However, it needs regular calibrations with a standard aerosol (every six month) on-site to quality-assure the measurement. Additionally, annual or biannual calibrations the CCNC against a reference instrument are required. In case CCNC performance is not controlled, CCNC flow might change with time causing an undefined supersaturation in the instrument and a bias in the measured number concentration.

### 3.1.10 Mass concentration of non-refractory particulate organics and inorganics

An Aerosol Chemical Speciation Monitor is designed for in situ measurement of non-refractory submicron (NR-PM1) aerosol chemical species, on a time-basis of typically 30 min. Measured species include nitrate, sulphate, ammonium, chloride and organic aerosols. Further data treatments are also allowing for source apportionment studies, notably of the organic fraction. It is based on a rather simple and robust technology, and its suitability for continuous monitoring has been demonstrated within ACTRIS in the last 6 years. However, its operation and data production required the involvement of experienced users. Indeed, several calibration steps must be completed regularly and non-trivial raw data correction procedures have to be performed carefully. Moreover, the instrument technology and data treatment tools (e.g., upgrade of key parts of the analyser, detection and adjustments of measurement artefacts, etc.) are still constantly evolving. It is then necessary to perform intercomparison campaigns and update best practice documents, in order to ensure accurate final data products. The uncertainty of the latter ones will notably depend on the availability of the TC unit to evaluate and harmonize the procedures raw data correction, notably including correction of measurement artefacts.

### 3.1.11 Nanoparticle number concentration

Atmospheric aerosol number concentration below 0.002 µm in size (Kulmala et al. 2012) is observed with a Particle Size Magnifier, which is a dual stage Condensation Particle Counter (Vanhanen et al. 2011). In the PSM the aerosol is turbulently mixed with air saturated with di-ethylene glycol, therefore creating a supersaturation high enough to activate even 0.001 µm ions, the nominal cut-off size being about 0.0015 µm. The 50% activation diameter can be varied between 0.001 and 0.0025 µm in mobility diameter by changing the mixing ratio of the saturator and sample flows. The PSM allows us to determine aerosol number concentrations between 0.001 to 0.0025 µm as well as their initial growth rate as a function of particle size (Lehtipalo et al. 2014). This will enable comparison between number concentration measurements with larger cut-off diameters. Similar instruments are now in the market by other manufacturers as well.
### 3.1.9 Cloud condensation nuclei number concentration

A cloud condensation nuclei counter (CCNC) is used to measure the Cloud condensation nuclei number concentration at different supersaturations and possibly as function of particle size. The technology is established and is commercially available from one manufacturers. The CCNC designed for long-term operations. However, it needs regular calibrations with a standard aerosol (every six month) on-site to quality-assure the measurement. Additionally, annual or biannual calibrations the CCNC against a reference instrument are required. In case CCNC performance is not controlled, CCNC flow might change with time causing an undefined supersaturation in the instrument and a bias in the measured number concentration.

### 3.1.10 Mass concentration of non-refractory particulate organics and inorganics

An Aerosol Chemical Speciation Monitor is designed for in situ measurement of non-refractory submicron (NR-PM1) aerosol chemical species, on a time-basis of typically 30 min. Measured species include nitrate, sulphate, ammonium, chloride and organic aerosols. Further data treatments are also allowing for source apportionment studies, notably of the organic fraction. It is based on a rather simple and robust technology, and its suitability for continuous monitoring has been demonstrated within ACTRIS in the last 6 years. However, its operation and data production required the involvement of experienced users. Indeed, several calibration steps must be completed regularly and non-trivial raw data correction procedures have to be performed carefully. Moreover, the instrument technology and data treatment tools (e.g., upgrade of key parts of the analyser, detection and adjustments of measurement artefacts, etc.) are still constantly evolving. It is then necessary to perform intercomparison campaigns and update best practice documents, in order to ensure accurate final data products. The uncertainty of the latter ones will notably depend on the availability of the TC unit to evaluate and harmonize the procedures raw data correction, notably including correction of measurement artefacts.

### 3.1.11 Nanoparticle number concentration

Atmospheric aerosol number concentration below 0.002 µm in size (Kulmala et al. 2012) is observed with a Particle Size Magnifier, which is a dual stage Condensation Particle Counter (Vanhanen et al. 2011). In the PSM the aerosol is turbulently mixed with air saturated with di-ethylene glycol, therefore creating a supersaturation high enough to activate even 0.001 µm ions, the nominal cut-off size being about 0.0015 µm. The 50% activation diameter can be varied between 0.001 and 0.0025 µm in mobility diameter by changing the mixing ratio of the saturator and sample flows. The PSM allows us to determine aerosol number concentrations between 0.001 to 0.0025 µm as well as their initial growth rate as a function of particle size (Lehtipalo et al. 2014). This will enable comparison between number concentration measurements with larger cut-off diameters. Similar instruments are now in the market by other manufacturers as well.
3.1.12 Nanoparticle number size distribution

There is a need to extend the size range of ACTRIS MPPS systems (Wiedensohler et al. 2012) below 0.02 µm. Here we utilize a well-established ultra-fine DMPS system of Aalto et al. 2001. However, we will drive towards development by utilizing higher resolution differential mobility analysis in combination with higher flow rate condensation particle counter and minimized particle diffusion losses in the sampling line as illustrated in Kangasluoma et al. 2017 (submitted). This facilitates better counting statistics in low concentrations as well as more detailed size classification in sub-0.01 µm size range.

Neutral Cluster and Air Ion Spectrometer (NAIS) measures electrical mobility distribution of naturally charged and total nanoparticles in high time resolution utilizing two parallel DMA columns. The size range is 0.002 – 0.042 µm and 0.0008 – 0.042 µm for the neutral aerosols and ions, respectively. The NAIS is a robust, field-worthy instrument, which can be operated for extended periods unattended (Manninen et al. 2010).
3.1.12 Nanoparticle number size distribution

There is a need to extend the size range of ACTRIS MPPS systems (Wiedensohler et al. 2012) below 0.02 µm. Here we utilize a well-established ultra-fine DMPS system of Aalto et al. 2001. However, we will drive towards development by utilizing higher resolution differential mobility analysis in combination with higher flow rate condensation particle counter and minimized particle diffusion losses in the sampling line as illustrated in Kangasluoma et al. 2017 (submitted). This facilitates better counting statistics in low concentrations as well as more detailed size classification in sub-0.01 µm size range.

Neutral Cluster and Air Ion Spectrometer (NAIS) measures electrical mobility distribution of naturally charged and total nanoparticles in high time resolution utilizing two parallel DMA columns. The size range is 0.002 – 0.042 µm and 0.0008 – 0.042 µm for the neutral aerosols and ions, respectively. The NAIS is a robust, field-worthy instrument, which can be operated for extended periods unattended (Manninen et al. 2010).
## 3.2 Estimation of the need

Numbers in the following table are based on QA/QC expert estimates and information by the countries how many NFs they potentially want to contribute to ACTRIS.

<table><thead><tr><th rowspan="3">Variable</th><th colspan="3">Number of NFs to which the TC is providing operation support</th></tr><tr><th>Now</th><th colspan="2">by 2025</th></tr><tr><th></th><th>Min.</th><th>Max.</th></tr></thead><tbody><tr><td>1. Particle number size distribution – mobility diameter</td><td>40</td><td>70</td><td>110</td></tr><tr><td>2. Particle light scattering and backscattering coefficient</td><td>40</td><td>70</td><td>110</td></tr><tr><td>3. Particle light absorption coefficient and equivalent black carbon concentration</td><td>50</td><td>70</td><td>110</td></tr><tr><td>4. Mass concentration of particulate organic and elemental carbon</td><td>20</td><td>30</td><td>55</td></tr><tr><td>5. Particle number size distribution - optical and aerodynamic diameter</td><td>10</td><td>30</td><td>55</td></tr><tr><td>6. Particle number concentration</td><td>10</td><td>30</td><td>55</td></tr><tr><td>7. Mass concentration of particulate elements</td><td>5</td><td>30</td><td>55</td></tr><tr><td>8. Mass concentration of particulate organic tracers</td><td>5</td><td>20</td><td>55</td></tr><tr><td>9. Cloud condensation nuclei number concentration</td><td>10</td><td>30</td><td>55</td></tr><tr><td>10. Mass concentration of non-refractory particulate organics and inorganics</td><td>20</td><td>15</td><td>40</td></tr><tr><td>11. Nanoparticle number concentration</td><td>5</td><td>20</td><td>40</td></tr><tr><td>12. Nanoparticle number size distribution</td><td>10</td><td>30</td><td>55</td></tr></tbody></table>
## 3.2 Estimation of the need

Numbers in the following table are based on QA/QC expert estimates and information by the countries how many NFs they potentially want to contribute to ACTRIS.

<table><thead><tr><th rowspan="3">Variable</th><th colspan="3">Number of NFs to which the TC is providing operation support</th></tr><tr><th>Now</th><th colspan="2">by 2025</th></tr><tr><th></th><th>Min.</th><th>Max.</th></tr></thead><tbody><tr><td>1. Particle number size distribution – mobility diameter</td><td>40</td><td>70</td><td>110</td></tr><tr><td>2. Particle light scattering and backscattering coefficient</td><td>40</td><td>70</td><td>110</td></tr><tr><td>3. Particle light absorption coefficient and equivalent black carbon concentration</td><td>50</td><td>70</td><td>110</td></tr><tr><td>4. Mass concentration of particulate organic and elemental carbon</td><td>20</td><td>30</td><td>55</td></tr><tr><td>5. Particle number size distribution - optical and aerodynamic diameter</td><td>10</td><td>30</td><td>55</td></tr><tr><td>6. Particle number concentration</td><td>10</td><td>30</td><td>55</td></tr><tr><td>7. Mass concentration of particulate elements</td><td>5</td><td>30</td><td>55</td></tr><tr><td>8. Mass concentration of particulate organic tracers</td><td>5</td><td>20</td><td>55</td></tr><tr><td>9. Cloud condensation nuclei number concentration</td><td>10</td><td>30</td><td>55</td></tr><tr><td>10. Mass concentration of non-refractory particulate organics and inorganics</td><td>20</td><td>15</td><td>40</td></tr><tr><td>11. Nanoparticle number concentration</td><td>5</td><td>20</td><td>40</td></tr><tr><td>12. Nanoparticle number size distribution</td><td>10</td><td>30</td><td>55</td></tr></tbody></table>
3.3 Timeline for implementation of the mandatory operation support

<table><thead><tr><th rowspan="2">Mode</th><th rowspan="2">Operation support</th><th rowspan="2">Type</th><th>Preparation phase</th><th>Implementation phase</th><th>Operation phase</th></tr><tr><th>&lt;2020</th><th>2020-2025</th><th>&gt;2025</th></tr></thead><tbody><tr><td rowspan="3">In situ measurements</td><td>Measurement guidelines</td><td>On request</td><td>Edition of SOPs for measurements for which they do not exist yet</td><td>Review and revision of existing SOPs</td><td>Review and revision of existing SOPs</td></tr><tr><td>Instrument-specific calibration workshop at TC facility</td><td>Scheduled</td><td>Test of calibration exercises</td><td>Regular calibration exercises</td><td>Regular calibration exercises</td></tr><tr><td>Site performance test with reference instruments operated at NFs</td><td>Scheduled</td><td>Decision on which kind of tests shall be carried out, provision of reference instruments, test exercises</td><td>Site performance tests with reference instruments</td><td>Site performance tests with reference instruments</td></tr><tr><td>In situ sampling</td><td>Laboratory intercomparison at NFs</td><td>Scheduled</td><td>Decision on which kind of Round-Robin tests shall be carried out, test exercises</td><td>Site performance tests with reference samples</td><td>Site performance tests with reference samples</td></tr><tr><td>In situ measurements or sampling</td><td>Training of operators and scientists</td><td>Scheduled</td><td>Decision on which kind of training shall be provided with which frequency, test exercises</td><td>Regular training according to schedule</td><td>Regular training according to schedule</td></tr></tbody></table>
3.3 Timeline for implementation of the mandatory operation support

<table><thead><tr><th rowspan="2">Mode</th><th rowspan="2">Operation support</th><th rowspan="2">Type</th><th>Preparation phase</th><th>Implementation phase</th><th>Operation phase</th></tr><tr><th>&lt;2020</th><th>2020-2025</th><th>&gt;2025</th></tr></thead><tbody><tr><td rowspan="3">In situ measurements</td><td>Measurement guidelines</td><td>On request</td><td>Edition of SOPs for measurements for which they do not exist yet</td><td>Review and revision of existing SOPs</td><td>Review and revision of existing SOPs</td></tr><tr><td>Instrument-specific calibration workshop at TC facility</td><td>Scheduled</td><td>Test of calibration exercises</td><td>Regular calibration exercises</td><td>Regular calibration exercises</td></tr><tr><td>Site performance test with reference instruments operated at NFs</td><td>Scheduled</td><td>Decision on which kind of tests shall be carried out, provision of reference instruments, test exercises</td><td>Site performance tests with reference instruments</td><td>Site performance tests with reference instruments</td></tr><tr><td>In situ sampling</td><td>Laboratory intercomparison at NFs</td><td>Scheduled</td><td>Decision on which kind of Round-Robin tests shall be carried out, test exercises</td><td>Site performance tests with reference samples</td><td>Site performance tests with reference samples</td></tr><tr><td>In situ measurements or sampling</td><td>Training of operators and scientists</td><td>Scheduled</td><td>Decision on which kind of training shall be provided with which frequency, test exercises</td><td>Regular training according to schedule</td><td>Regular training according to schedule</td></tr></tbody></table>
## 3.4 Operation support for quality assurance and quality control

### 3.4.1 Definition and establishment of standard operation procedures

#### 3.4.1.1 Particle number size distribution – mobility diameter

Measurement guidelines to operate mobility particle size spectrometers for long-term atmospheric observations have been developed during EUSAAR and ACTRIS, These have been published in Wiedensohler et al. (2012) as well as in the WMO/GAW Aerosol Measurement Procedures, Guidelines and Recommendations (report no 227).

See also http://www.wmo-gaw-wcc-aerosol-physics.org/recommen-dations.html

For the existing NFs, the guidelines should be in place.

#### 3.4.1.2 Particle light scattering and backscattering coefficient

Measurement guidelines to operate integrating nephelometer for long-term atmospheric observations have been developed during EUSAAR, ACTRIS and within the GAW community. These have been published in the WMO/GAW Aerosol Measurement Procedures, Guidelines and Recommendations (report no 227).

See also http://www.wmo-gaw-wcc-aerosol-physics.org/recommen-dations.html

For the existing NFs, the guidelines should be in place.

#### 3.4.1.3 Particle light absorption coefficient and equivalent black carbon concentration

Measurement guidelines to operate absorption photometers for long-term atmospheric observations have been developed during EUSAAR, ACTRIS and within the GAW community, These have been published in the WMO/GAW Aerosol Measurement Procedures, Guidelines and Recommendations, report no 227.

See also http://www.wmo-gaw-wcc-aerosol-physics.org/recommen-dations.html

For the existing NFs, the guidelines should be in place.

#### 3.4.1.4 Mass concentration of particulate organic and elemental carbon

A European standard (EN 16909) for the measurement of OC and EC in ambient PM samples deposited on filters has been published (2017). It is mainly based and fully consistent with the SOP for the measurement of OC and EC developed under ACTRIS. The objectives of this SOP is that thermal-optical analysers are optimally operated, and above all that the necessary QA/QC operations are carried at the frequency needed to ensure data quality and traceability. The TC shall be responsible to check that the SOPs have been correctly followed before validating OC and EC data. While the SOP for off-line analyses is already in place, a SOP for semi-continuous instrument shall be developed, mainly focusing on the instrument calibration and participation in Round-Robin test. New SOPs shall be developed if new instrumentation types emerge.
3.4 Operation support for quality assurance and quality control

3.4.1 Definition and establishment of standard operation procedures

3.4.1.1 Particle number size distribution – mobility diameter

Measurement guidelines to operate mobility particle size spectrometers for long-term atmospheric
observations have been developed during EUSAAR and ACTRIS, These have been published in
Wiedensohler et al. (2012) as well as in the WMO/GAW Aerosol Measurement Procedures, Guidelines
and Recommendations (report no 227).

See also http://www.wmo-gaw-wcc-aerosol-physics.org/recommen-dations.html

For the existing NFs, the guidelines should be in place.

3.4.1.2 Particle light scattering and backscattering coefficient

Measurement guidelines to operate integrating nephelometer for long-term atmospheric observations have been developed during EUSAAR, ACTRIS and within the GAW community. These have been published in the WMO/GAW Aerosol Measurement Procedures, Guidelines and Recommendations (report no 227).

See also http://www.wmo-gaw-wcc-aerosol-physics.org/recommen-dations.html

For the existing NFs, the guidelines should be in place.

3.4.1.3 Particle light absorption coefficient and equivalent black carbon concentration

Measurement guidelines to operate absorption photometers for long-term atmospheric observations have been developed during EUSAAR, ACTRIS and within the GAW community, These have been published in the WMO/GAW Aerosol Measurement Procedures, Guidelines and Recommendations, report no 227.

See also http://www.wmo-gaw-wcc-aerosol-physics.org/recommen-dations.html

For the existing NFs, the guidelines should be in place.

3.4.1.4 Mass concentration of particulate organic and elemental carbon

A European standard (EN 16909) for the measurement of OC and EC in ambient PM samples deposited on filters has been published (2017). It is mainly based and fully consistent with the SOP for the measurement of OC and EC developed under ACTRIS. The objectives of this SOP is that thermal-optical analysers are optimally operated, and above all that the necessary QA/QC operations are carried at the frequency needed to ensure data quality and traceability. The TC shall be responsible to check that the SOPs have been correctly followed before validating OC and EC data. While the SOP for off-line analyses is already in place, a SOP for semi-continuous instrument shall be developed, mainly focusing on the instrument calibration and participation in Round-Robin test. New SOPs shall be developed if new instrumentation types emerge.
3.4.1.5 Particle number size distribution – optical and aerodynamic diameter

Measurement guidelines for optical and aerodynamic particle size spectrometers have not been
developed for atmospheric observations. This is the task for the preparation phase of ACTRIS, working
together with metrology institutes.

3.4.1.6 Particle number concentration

Measurement guideline for condensation particle counters are described in the standard FprCEN/TS 16976 developed in the working group CEN TC 264, WG 32, in which ACTRIS was actively was involved.

3.4.1.7 Mass concentration of particulate elements

Firstly SOPs shall be developed tailored to each analytical technique, then these SOPs shall be distributed to the NFs, and discussed and trained within the trainings at the TC. The successful implementation of the SOPs shall be controlled by continuous inter-laboratory comparisons. All SOPs (if not already available at the TC) shall be developed during the implementation phase and shall be fully available with the start of the operational phase. SOPs will address the sample treatment (filter material, sampling procedure, level of purity for solvents and extraction procedures when applicable, sample storage, etc.) and the use of proper calibration standards.

3.4.1.8 Mass concentration of particulate organic tracers

At a first stage SOPs shall be developed focusing on sample preparation, as this strongly affects the results of the analysis. In a second stage SOPs shall be provided recommending certain measurement techniques for each class of compounds to be analysed. These SOPs shall be distributed to the NFs and discussed and trained within the trainings at the TC. The successful implementation of the SOPs shall be controlled by continuous ILCs. If certain users are not able to follow the recommend measurement techniques (e.g. due to money issues) the TC will provide minimum requirements on alternative techniques (calibration, response factors, detection limits etc.).

All SOPs (if not already available at the TC) shall be developed during the implementation phase and shall be fully available with the start of the operational phase. For new classes of compounds or if fundamental new techniques emerge the TC will provide improved SOPs. Besides the recommendation of certain measurement techniques SOPs will address the following points:

* sample treatment: filter material, sampling proceeding, level of purity for solvents, extraction proceeding, derivatisation proceeding (if applicable), sample storage and maximum storage time

- authentic standard compounds: supplier or synthesis proceeding, level of purity, storage, stability

3.4.1.9 Cloud condensation nuclei number concentration

Measurement guidelines to cloud condensation nuclei counter for long-term atmospheric observations have been developed during ACTRIS. They are available at http://actrisnilu.no/Content/SOP. For the existing NFs, the guidelines should be in place.
3.4.1.5 Particle number size distribution – optical and aerodynamic diameter

Measurement guidelines for optical and aerodynamic particle size spectrometers have not been
developed for atmospheric observations. This is the task for the preparation phase of ACTRIS, working
together with metrology institutes.

3.4.1.6 Particle number concentration

Measurement guideline for condensation particle counters are described in the standard FprCEN/TS 16976 developed in the working group CEN TC 264, WG 32, in which ACTRIS was actively was involved.

3.4.1.7 Mass concentration of particulate elements

Firstly SOPs shall be developed tailored to each analytical technique, then these SOPs shall be distributed to the NFs, and discussed and trained within the trainings at the TC. The successful implementation of the SOPs shall be controlled by continuous inter-laboratory comparisons. All SOPs (if not already available at the TC) shall be developed during the implementation phase and shall be fully available with the start of the operational phase. SOPs will address the sample treatment (filter material, sampling procedure, level of purity for solvents and extraction procedures when applicable, sample storage, etc.) and the use of proper calibration standards.

3.4.1.8 Mass concentration of particulate organic tracers

At a first stage SOPs shall be developed focusing on sample preparation, as this strongly affects the results of the analysis. In a second stage SOPs shall be provided recommending certain measurement techniques for each class of compounds to be analysed. These SOPs shall be distributed to the NFs and discussed and trained within the trainings at the TC. The successful implementation of the SOPs shall be controlled by continuous ILCs. If certain users are not able to follow the recommend measurement techniques (e.g. due to money issues) the TC will provide minimum requirements on alternative techniques (calibration, response factors, detection limits etc.).

All SOPs (if not already available at the TC) shall be developed during the implementation phase and shall be fully available with the start of the operational phase. For new classes of compounds or if fundamental new techniques emerge the TC will provide improved SOPs. Besides the recommendation of certain measurement techniques SOPs will address the following points:

* sample treatment: filter material, sampling proceeding, level of purity for solvents, extraction proceeding, derivatisation proceeding (if applicable), sample storage and maximum storage time

- authentic standard compounds: supplier or synthesis proceeding, level of purity, storage, stability

3.4.1.9 Cloud condensation nuclei number concentration

Measurement guidelines to cloud condensation nuclei counter for long-term atmospheric observations have been developed during ACTRIS. They are available at http://actrisnilu.no/Content/SOP. For the existing NFs, the guidelines should be in place.
3.4.1.10 Mass concentration of non-refractory particulate organics and inorganics

Preliminary measurement guidelines have been defined within ACTRIS FP7 and ACTRIS2 H2020 projects. The TC unit shall be responsible for further updating related documents as well as new measurement guidelines for the ACSM calibration and operation. It shall also define rules for the transformation of raw data into level 1.5 validated data. All relevant procedures shall be openly shared and discussed amongst the user community, and will evolve over time based on the improving knowledge of the instrument operation. Likewise, the TC might develop and implement new measurement guidelines for every additional online aerosol chemical monitors being included into the field of the ACTRIS aerosol in situ TC (e.g. note that the TC unit will not be responsible for establishing procedures for the repair or heavy maintenance of the instrument (which is left to the manufacturer), but it can participate in the elaboration and/or the diffusion (e.g., through wiki pages, dedicated website, ...) of relevant material (such as technical videos, e-learning tutorials, etc.).

3.4.1.11 Nanoparticle number concentration

The optimization and harmonization work of the number concentration measurements with the PSM relies on the work presented in Kangasluoma et al. 2016, which describes the inlet configurations. In the next years this is complemented by including a standardized method for performing a PSM cut-off calibration with one organic and one inorganic test aerosol, and a harmonized sample dilution that is a prerequisite in high number concentration environments, such as in China. Further harmonization for the field operation of the PSM shall be provided with regards to the particle composition and sample flow temperature and RH. The PSM data inversion is described in Lehtipalo et al. 2014. The knowledge is collected into a PSM SOP by 2021.

The responsibility of the TC is to develop and refine the abovementioned SOPs and distribute them within ACTRIS RI. The process is facilitated by SOP workshops organized at the TC for the NF operators.

3.4.1.12 Nanoparticle number size distribution

The procedures and measurements with the NAIS instrument was harmonized in ACTRIS. The corresponding document is published for the scientific audience in Manninen et al. 2016. This document describes the installation, sampling, operation and data analysis procedures for the NAIS. Within EUCAARI-project (Kulmala et al. 2010), the NAIS data protocols were developed enabling data delivery to EBAS. This shall be reinstated and put into operational phase by 2021 with near real-time data delivery.

The sub-0.01 µm size distribution measurements follow the general guidelines and best practices set for sub-micron aerosol number size distribution measurements (Wiedensohler et al. 2012) with the specific focus on minimizing nanoparticle losses by optimizing the sample lines and increasing sample flow rates. A new SOP for the sub-0.01 µm size distribution shall be elaborated during the following years and the use of high resolution Differential Mobility Analysers and higher sample flow rates for the Condensation Particle Counters are explored. The technical target for this activity is to improve the coherence of sub-0.01 µm size distribution measurements and bring this capacity into a wider use within ACTRIS. The next for the SOPs should be ready by 2025.
3.4.1.10 Mass concentration of non-refractory particulate organics and inorganics

Preliminary measurement guidelines have been defined within ACTRIS FP7 and ACTRIS2 H2020 projects. The TC unit shall be responsible for further updating related documents as well as new measurement guidelines for the ACSM calibration and operation. It shall also define rules for the transformation of raw data into level 1.5 validated data. All relevant procedures shall be openly shared and discussed amongst the user community, and will evolve over time based on the improving knowledge of the instrument operation. Likewise, the TC might develop and implement new measurement guidelines for every additional online aerosol chemical monitors being included into the field of the ACTRIS aerosol in situ TC (e.g. note that the TC unit will not be responsible for establishing procedures for the repair or heavy maintenance of the instrument (which is left to the manufacturer), but it can participate in the elaboration and/or the diffusion (e.g., through wiki pages, dedicated website, ...) of relevant material (such as technical videos, e-learning tutorials, etc.).

3.4.1.11 Nanoparticle number concentration

The optimization and harmonization work of the number concentration measurements with the PSM relies on the work presented in Kangasluoma et al. 2016, which describes the inlet configurations. In the next years this is complemented by including a standardized method for performing a PSM cut-off calibration with one organic and one inorganic test aerosol, and a harmonized sample dilution that is a prerequisite in high number concentration environments, such as in China. Further harmonization for the field operation of the PSM shall be provided with regards to the particle composition and sample flow temperature and RH. The PSM data inversion is described in Lehtipalo et al. 2014. The knowledge is collected into a PSM SOP by 2021.

The responsibility of the TC is to develop and refine the abovementioned SOPs and distribute them within ACTRIS RI. The process is facilitated by SOP workshops organized at the TC for the NF operators.

3.4.1.12 Nanoparticle number size distribution

The procedures and measurements with the NAIS instrument was harmonized in ACTRIS. The corresponding document is published for the scientific audience in Manninen et al. 2016. This document describes the installation, sampling, operation and data analysis procedures for the NAIS. Within EUCAARI-project (Kulmala et al. 2010), the NAIS data protocols were developed enabling data delivery to EBAS. This shall be reinstated and put into operational phase by 2021 with near real-time data delivery.

The sub-0.01 µm size distribution measurements follow the general guidelines and best practices set for sub-micron aerosol number size distribution measurements (Wiedensohler et al. 2012) with the specific focus on minimizing nanoparticle losses by optimizing the sample lines and increasing sample flow rates. A new SOP for the sub-0.01 µm size distribution shall be elaborated during the following years and the use of high resolution Differential Mobility Analysers and higher sample flow rates for the Condensation Particle Counters are explored. The technical target for this activity is to improve the coherence of sub-0.01 µm size distribution measurements and bring this capacity into a wider use within ACTRIS. The next for the SOPs should be ready by 2025.
The responsibility of the TC is to develop and refine the abovementioned SOPs and distribute them within ACTRIS RI. The process is facilitated by SOP workshops organized at the TC for the NF operators.

## 3.4.2 Definition of measurement quality-assurance criteria and procedures

### 3.4.2.1 Particle number size distribution – mobility diameter

The on-site quality assurance are described in detail in the publication of Wiedensohler et al. (2012) and at http://www.wmo-gaw-wcc-aerosol-physics.org/recommen-dations.html

Diagnostic data from the MPSS such as temperature, relative humidity and flow rates are the base for data flagging.

### 3.4.2.2 Particle light scattering and backscattering coefficient

Quality assurance procedures are related to on-site gas calibrations, which have to be done regularly as described at http://www.wmo-gaw-wcc-aerosol-physics.org/recommen-dations.html. Diagnostic data such as the relative humidity are the base for data flagging.

### 3.4.2.3 Particle light absorption coefficient and equivalent black carbon concentration

On-site quality assurance procedures have to be developed during the ATRIS preparation phase. Diagnostic data such as the relative humidity and flow rate are the base for data flagging.

### 3.4.2.4 Mass concentration of particulate organic and elemental carbon

The quality assurance criteria (bias and variability) defined for the measurement of OC and EC under ACTRIS and already included to the data files submitted to EBAS shall be determined by the specific TC Unit and communicated to beneficiaries. They shall be calculated from statistical analyses of the results of Round-Robin tests. The assigned values for OC and EC shall be determined from the robust average among the participant (ISO 13528). Additionally, synthetic reference samples shall be distributed to beneficiaries so that there measurements can be confronted to true values. The statistical outputs of the Round-Robin tests and the results of the analyses of the synthetic reference materials shall be used by the TC to investigate the reasons and the period for under-performance, if any. The data reported by the beneficiaries shall be flagged accordingly. The procedure for determining the data quality criteria shall be in place from the pre-operational phase. The TC shall adapt the thresholds for determining under-performance according to the evolution of analytical technologies.

### 3.4.2.5 Particle number size distribution – optical and aerodynamic diameter

Measurement quality assurance criteria and procedures for OPSS and APSS instruments currently only exist concerning particle sizing, using latex particles (Pfeifer et al., 2016). Criteria and calibration procedures for the size resolved particle number concentration are currently not existing, but are under development.
The responsibility of the TC is to develop and refine the abovementioned SOPs and distribute them within ACTRIS RI. The process is facilitated by SOP workshops organized at the TC for the NF operators.

## 3.4.2 Definition of measurement quality-assurance criteria and procedures

### 3.4.2.1 Particle number size distribution – mobility diameter

The on-site quality assurance are described in detail in the publication of Wiedensohler et al. (2012) and at http://www.wmo-gaw-wcc-aerosol-physics.org/recommen-dations.html

Diagnostic data from the MPSS such as temperature, relative humidity and flow rates are the base for data flagging.

### 3.4.2.2 Particle light scattering and backscattering coefficient

Quality assurance procedures are related to on-site gas calibrations, which have to be done regularly as described at http://www.wmo-gaw-wcc-aerosol-physics.org/recommen-dations.html. Diagnostic data such as the relative humidity are the base for data flagging.

### 3.4.2.3 Particle light absorption coefficient and equivalent black carbon concentration

On-site quality assurance procedures have to be developed during the ATRIS preparation phase. Diagnostic data such as the relative humidity and flow rate are the base for data flagging.

### 3.4.2.4 Mass concentration of particulate organic and elemental carbon

The quality assurance criteria (bias and variability) defined for the measurement of OC and EC under ACTRIS and already included to the data files submitted to EBAS shall be determined by the specific TC Unit and communicated to beneficiaries. They shall be calculated from statistical analyses of the results of Round-Robin tests. The assigned values for OC and EC shall be determined from the robust average among the participant (ISO 13528). Additionally, synthetic reference samples shall be distributed to beneficiaries so that there measurements can be confronted to true values. The statistical outputs of the Round-Robin tests and the results of the analyses of the synthetic reference materials shall be used by the TC to investigate the reasons and the period for under-performance, if any. The data reported by the beneficiaries shall be flagged accordingly. The procedure for determining the data quality criteria shall be in place from the pre-operational phase. The TC shall adapt the thresholds for determining under-performance according to the evolution of analytical technologies.

### 3.4.2.5 Particle number size distribution – optical and aerodynamic diameter

Measurement quality assurance criteria and procedures for OPSS and APSS instruments currently only exist concerning particle sizing, using latex particles (Pfeifer et al., 2016). Criteria and calibration procedures for the size resolved particle number concentration are currently not existing, but are under development.
3.4.2.6 Particle number concentration

On-site quality assurance procedures are described in the standard FprCEN/TS 16976 developed in the working group CEN TC 264, WG 32, in which ACTRIS was actively involved.

3.4.2.7 Mass concentration of particulate elements

The TC will provide protocols for each analytical technique that will address the key performance
parameters such as external and internal calibration standards, number of blank measurements, number
of repetitions, reproducibility, number of control samples. The developed protocols should be applied to
each analytical technique. When all minimum parameters are fulfilled data will be flagged as QA/QC
controlled. If the data do not passed the control they shall be still available but without flagging. The
protocols shall be developed during the implementation phase and shall be available in the operational
phase. Additionally, synthetic reference samples shall be distributed to beneficiaries so that their
measurements can be compared to true values. The statistical outputs of the Round-Robin tests and the
results of the analyses of the synthetic reference materials shall be used by the TC to investigate the
reasons of under-performances, if any. The data reported by the beneficiaries shall be flagged accordingly.
The TC shall adapt the thresholds for determining under-performance according to the evolution of
analytical technologies.

3.4.2.8 Mass concentration of particulate organic tracers

The TC will provide protocols for each recommended technique that will address the following key
performance parameters (in addition 3.3.1.1):

* external calibration: sequence design, concentration range, minimum number of dilution steps, minimum regression factor, number of blank measurements, storage and stability of standard dilutions

* measurement: column material for separation, number of repetitions, reproducibility, number of control samples

* mass calibration (if applicable): internal standard/calibrant composition

The developed protocol should be applied to each measurement and linked to created data set. Thus for each measurement the protocol is available. If all minimum parameters are fulfilled data can be flagged as QA/QC controlled. If the data do not passed the control they shall be still available but without flagging.

The protocols shall be developed during the implementation phase and are available in the operational phase. As this kind of protocols are not instrument specific they can be transfer to new emerging techniques. Nevertheless, for each emerging technique the TC will prove the applicability of the protocols and will provide updated recommendations (if necessary).

3.4.2.9 Cloud condensation nuclei number concentration

Quality assurance procedures have been developed during ACTRIS. They are available at
http://actris nilu no/Content/SOP. For the existing NFs, the guidelines should be in place.
3.4.2.6 Particle number concentration

On-site quality assurance procedures are described in the standard FprCEN/TS 16976 developed in the working group CEN TC 264, WG 32, in which ACTRIS was actively involved.

3.4.2.7 Mass concentration of particulate elements

The TC will provide protocols for each analytical technique that will address the key performance
parameters such as external and internal calibration standards, number of blank measurements, number
of repetitions, reproducibility, number of control samples. The developed protocols should be applied to
each analytical technique. When all minimum parameters are fulfilled data will be flagged as QA/QC
controlled. If the data do not passed the control they shall be still available but without flagging. The
protocols shall be developed during the implementation phase and shall be available in the operational
phase. Additionally, synthetic reference samples shall be distributed to beneficiaries so that their
measurements can be compared to true values. The statistical outputs of the Round-Robin tests and the
results of the analyses of the synthetic reference materials shall be used by the TC to investigate the
reasons of under-performances, if any. The data reported by the beneficiaries shall be flagged accordingly.
The TC shall adapt the thresholds for determining under-performance according to the evolution of
analytical technologies.

3.4.2.8 Mass concentration of particulate organic tracers

The TC will provide protocols for each recommended technique that will address the following key
performance parameters (in addition 3.3.1.1):

* external calibration: sequence design, concentration range, minimum number of dilution steps, minimum regression factor, number of blank measurements, storage and stability of standard dilutions

* measurement: column material for separation, number of repetitions, reproducibility, number of control samples

* mass calibration (if applicable): internal standard/calibrant composition

The developed protocol should be applied to each measurement and linked to created data set. Thus for each measurement the protocol is available. If all minimum parameters are fulfilled data can be flagged as QA/QC controlled. If the data do not passed the control they shall be still available but without flagging.

The protocols shall be developed during the implementation phase and are available in the operational phase. As this kind of protocols are not instrument specific they can be transfer to new emerging techniques. Nevertheless, for each emerging technique the TC will prove the applicability of the protocols and will provide updated recommendations (if necessary).

3.4.2.9 Cloud condensation nuclei number concentration

Quality assurance procedures have been developed during ACTRIS. They are available at
[http://actrisnilu.no/Content/SOP](http://actrisnilu.no/Content/SOP). For the existing NFs, the guidelines should be in place.
3.4.2.10 Mass concentration of non-refractory particulate organics and inorganics

Quality assurance for each instrument shall be based on a strict set of criteria for instrument setup at each observational site. Related quality assurance procedures notably include inspection of technical parameters (such as Air Beam value, mass spectrometer tunings, fittings for internal calibrations ...), check of the ion balance, and PM mass and/or optical closure exercises (by comparison with collocated instruments). These criteria shall be defined and revised as part of the measurement guidelines. They will provide confidence to the NF and the TC, as well as ACTRIS as a whole, ensuring that quality requirements are fulfilled and/or less quality data are accurately flagged.

3.4.2.11 Nanoparticle number concentration

The procedures and criteria of the sub-0.01 µm total number concentration data are or shall be described
in the developed SOPs (see 3.3.1). The technical target for the measurements is to provide harmonized
observations in NRT data delivery. The NRT data stream shall be automatically flagged for preliminary
quality checks.

The following instrument maintenance procedures are required with the PSM:

* Yearly cut-off and CPC concentration calibration

* Monthly PSM and CPC inlet flow rate measurements

* CPC pulse width monitoring

* Regular PSM zero measurement using particle free air

* Removing excess diethylene glycol from tubing as needed.

These procedures shall be elaborated in the SOPs for the PSM developed by the TC. In order to reach higher level data, automatic flagging shall be developed based on measured instrument operation parameters followed by manual data quality assurance by an expert, re-inversion if needed, flagging or removal of bad quality data.

The criteria and procedures for the PSM are intended to be in place 2019, co-incident with the
development of the SOPs.

3.4.2.12 Nanoparticle number size distribution

The procedures and criteria of the sub-0.01 µm size distribution data are or shall be described in the
developed SOPs (see 3.3.1). The technical target for the measurements is to provide harmonized
observations in NRT data delivery. The NRT data stream shall be automatically flagged for preliminary
quality checks.

The following instrument maintenance procedures are required with the NAIS:

* DMA column cleaning as needed,

* Ion and particle concentration and sizing calibration yearly,

* Inlet flow rate measurement monthly,

* Electrometer zero current monitoring.
3.4.2.10 Mass concentration of non-refractory particulate organics and inorganics

Quality assurance for each instrument shall be based on a strict set of criteria for instrument setup at each observational site. Related quality assurance procedures notably include inspection of technical parameters (such as Air Beam value, mass spectrometer tunings, fittings for internal calibrations ...), check of the ion balance, and PM mass and/or optical closure exercises (by comparison with collocated instruments). These criteria shall be defined and revised as part of the measurement guidelines. They will provide confidence to the NF and the TC, as well as ACTRIS as a whole, ensuring that quality requirements are fulfilled and/or less quality data are accurately flagged.

3.4.2.11 Nanoparticle number concentration

The procedures and criteria of the sub-0.01 µm total number concentration data are or shall be described
in the developed SOPs (see 3.3.1). The technical target for the measurements is to provide harmonized
observations in NRT data delivery. The NRT data stream shall be automatically flagged for preliminary
quality checks.

The following instrument maintenance procedures are required with the PSM:

* Yearly cut-off and CPC concentration calibration

* Monthly PSM and CPC inlet flow rate measurements

* CPC pulse width monitoring

* Regular PSM zero measurement using particle free air

* Removing excess diethylene glycol from tubing as needed.

These procedures shall be elaborated in the SOPs for the PSM developed by the TC. In order to reach higher level data, automatic flagging shall be developed based on measured instrument operation parameters followed by manual data quality assurance by an expert, re-inversion if needed, flagging or removal of bad quality data.

The criteria and procedures for the PSM are intended to be in place 2019, co-incident with the
development of the SOPs.

3.4.2.12 Nanoparticle number size distribution

The procedures and criteria of the sub-0.01 µm size distribution data are or shall be described in the
developed SOPs (see 3.3.1). The technical target for the measurements is to provide harmonized
observations in NRT data delivery. The NRT data stream shall be automatically flagged for preliminary
quality checks.

The following instrument maintenance procedures are required with the NAIS:

* DMA column cleaning as needed,

* Ion and particle concentration and sizing calibration yearly,

* Inlet flow rate measurement monthly,

* Electrometer zero current monitoring.
The NRT data stream shall be automatically flagged for preliminary quality checks. In order to reach higher level data, automatic flagging shall be developed based on measured instrument operation parameters followed by manual data quality assurance by an expert, re-inversion if needed, flagging or removal of bad quality data.

The UF-DMPS data quality assurance requires the same procedures as in ACTRIS documentation for the DMPS systems with the specific focus on sub-0.02 µm size distribution.

The criteria and procedures are intended to be in place 2021 (NAIS) and 2025 (UF-DMPS), co-incident with the development of the SOPs.

### 3.4.3 Development and provision of instrument-specific calibration

#### 3.4.3.1 Particle number size distribution – mobility diameter

The calibration procedures of MPSS have been described in Wiedensohler et al. (2017) and are already applied during ACTRIS2. For the calibration at the calibration facility reference a MPSS, a CPC and a FCAE are needed. On-site intercomparisons include a MPSS and a CPC. Size calibrations are done with a certified PSL particle standard.

#### 3.4.3.2 Particle light scattering and backscattering coefficient

For the calibration of integrating nephelometers, particle free air and CO2 is used. Calibration are also done at the calibration facility against a frequently calibrated reference integrating nephelometer

#### 3.4.3.3 Particle light absorption coefficient and equivalent black carbon concentration

A reference set-up for absorption photometers was developed during ACTRIS2, see deliverable D34. This set-up includes a three extinction monitors for three different wavelengths and a multi-wavelengths integrating nephelometer. Laboratory-generated sulphate aerosol is used to calibrate the reference set-up. The absorption photometers are calibrated against the reference set-up and a reference absorption photometer using an absorbing aerosol.

There is no reference for the equivalent black carbon concentration mass concentration yet. This shall be a task for the preparation phase of ACTRIS.

#### 3.4.3.4 Mass concentration of particulate organic and elemental carbon

The TC will provide remote access to its facilities for calibrating measurements of OC and EC in ambient PM samples deposited on filters. Round-Robin test shall be organised at least once a year from the beginning of the pre-operational phase, in order to cover all requests from beneficiaries. Synthetic certified materials shall be made available to beneficiaries at least from the beginning of the operational phase.