## 8.2.2 Technical obligations in relation with the ACTRIS Data Centre

The following general share of responsibilities between the Centre for Aerosol Remote Sensing and the ACTRIS Data Centre applies:

<table><thead><tr><td>Responsibilities at CIS</td><td>Responsibilities at ACTRIS DC</td></tr></thead><tbody><tr><td>The Centre for Aerosol Remote Sensing is responsible for developing and facilitating the implementation of the QA/QC procedures and tools at the ACTRIS NFs operating cloud in situ instruments, INP instruments and offline chemical analytics, in order to allow the respective NFs to keep control on the quality of their measurements (level 0 data)</td><td>ACTRIS Data Centre is responsible for the QC of the ACTRIS data produced from the respective measurements (level 1 to level 3 data), which are made available through the ACTRIS data portal</td></tr><tr><td>The Centre for Aerosol Remote Sensing is responsible for auditing the ACTRIS NFs operating cloud in situ instruments, INP instruments and offline chemical analytics, documenting the quality of the measurements, and providing all results to the ACTRIS Data Centre, in order to allow the traceability of the ACTRIS data which are made available through the ACTRIS data portal</td><td>ACTRIS Data Centre is responsible for the traceability and full documentation of the data quality of the ACTRIS data produced cloud in situ instruments, INP instruments and offline chemical analytics, which are made available through the ACTRIS data portal. Results of quality assurance procedures applied by the Centre for Cloud In Situ Measurements will be traced into the data products.</td></tr><tr><td>The Centre for Aerosol Remote Sensing is responsible for developing and testing new retrieval algorithms or tools for producing level 1 to 3 data, including the exploitation of instrument synergies</td><td>ACTRIS Data Centre is responsible for implementing the approved retrieval algorithms or tools into the ACTRIS Data Centre operation</td></tr></tbody></table>

The workflow between the ACTRIS NFs, the Centre for Cloud In Situ Measurements and the ACTRIS Data Centre is as follows:

* CIS develops and provides QA/QC procedures

* ACTRIS NF implements and applies QA/QC procedures and participates in audits

* ACTRIS NF delivers level 0 data to the DC for archiving and to CIS for quality control and approval

* The NF creates level 1 and level 2 data according to procedures implemented and approved by CIS and send these data to the data centre for archiving

* For variables with automatic quality control the DC will process the level 0 data.
### 8.2.3 Technical obligations in relation with the Centre for Aerosol In Situ Measurements

Service for inlets as well as instruments operated at ACTRIS NFs will be serviced by the Centre for Aerosol In Situ Measurements. Aerosol instruments needed at CIS units for measuring and controlling aerosols during INP instrument calibrations have to be serviced and calibrated at the Centre for Aerosol In Situ Measurements. An intensive communication between CIS and the Centre for Aerosol In Situ Measurements is mandatory to ensure high quality of the total and interstitial aerosol data measured at observational platforms.

### 8.2.4 Technical obligations in relation with the ACTRIS users

The Centre for Cloud In Situ Measurements should commit to provide a minimum amount of user services as described in section 4. The provision of services will be made on case-by case situation.

## 8.3 Evaluation of the activity of Centre for Cloud In Situ Measurements

Once established and operational, the Centre for Cloud In Situ Measurements will be annually evaluated for its performance, against the following Key Performance indicators (KPIs). The KPI and the corresponding scores are listed in Table 8-1.

<table><caption>Table 8-1: Key Performance indicators for the yearly evaluation of the CIS activities</caption><thead><tr><th>Criteria</th><th>Indicator</th><th>Planned value</th><th>Achieved value</th><th>Percentage of achievement<sup>1</sup></th><th>Weight</th></tr></thead><tbody><tr><td colspan="6" style="background-color: #D2B48C; text-align: center; font-weight: bold;">GENERAL SCORE</td></tr><tr><td rowspan="5" style="vertical-align: top; text-align: center; font-weight: bold;">Usefulness for ACTRIS NFs</td><td style="font-weight: bold;">CRITERIA TOTAL SCORE</td><td></td><td></td><td></td><td rowspan="5" style="text-align: center; vertical-align: middle;">50%</td></tr><tr><td style="padding-left: 1em;">No. of operation support units provided to ACTRIS NFs for quality assurance and quality control</td><td></td><td></td><td></td></tr><tr><td style="padding-left: 1em;">No. of operation support units provided to ACTRIS NFs for knowledge transfer and training</td><td></td><td></td><td></td></tr><tr><td style="padding-left: 1em;">No. of operation support units provided to ACTRIS NFs for Improvement of measurement and data processing methodologies</td><td></td><td></td><td></td></tr><tr><td style="padding-left: 1em;">Average score of satisfaction received from NFs Including utility, fairness and timeliness of the activities for operation support</td><td></td><td></td><td></td></tr><tr><td rowspan="4" style="vertical-align: top; text-align: center; font-weight: bold;">Usefulness for ACTRIS users</td><td style="font-weight: bold;">CRITERIA TOTAL SCORE</td><td></td><td></td><td></td><td rowspan="4" style="text-align: center; vertical-align: middle;">20%</td></tr><tr><td style="padding-left: 1em;">No. of service units provided to ACTRIS users for quality assurance and quality control</td><td></td><td></td><td></td></tr><tr><td style="padding-left: 1em;">No. of service units provided to ACTRIS users for knowledge transfer and training</td><td></td><td></td><td></td></tr><tr><td style="padding-left: 1em;">No. of service units provided to ACTRIS users for improvement of measurement and data processing methodologies</td><td></td><td></td><td></td></tr></tbody></table>

<footnote n="1">¹ With regard to the planned and approved values</footnote>
### 8.2.3 Technical obligations in relation with the Centre for Aerosol In Situ Measurements

Service for inlets as well as instruments operated at ACTRIS NFs will be serviced by the Centre for Aerosol In Situ Measurements. Aerosol instruments needed at CIS units for measuring and controlling aerosols during INP instrument calibrations have to be serviced and calibrated at the Centre for Aerosol In Situ Measurements. An intensive communication between CIS and the Centre for Aerosol In Situ Measurements is mandatory to ensure high quality of the total and interstitial aerosol data measured at observational platforms.

### 8.2.4 Technical obligations in relation with the ACTRIS users

The Centre for Cloud In Situ Measurements should commit to provide a minimum amount of user services as described in section 4. The provision of services will be made on case-by case situation.

## 8.3 Evaluation of the activity of Centre for Cloud In Situ Measurements

Once established and operational, the Centre for Cloud In Situ Measurements will be annually evaluated for its performance, against the following Key Performance indicators (KPIs). The KPI and the corresponding scores are listed in Table 8-1.

<table><caption>Table 8-1: Key Performance indicators for the yearly evaluation of the CIS activities</caption><thead><tr><th>Criteria</th><th>Indicator</th><th>Planned value</th><th>Achieved value</th><th>Percentage of achievement<sup>1</sup></th><th>Weight</th></tr></thead><tbody><tr><td colspan="6" style="background-color: #d2b48c; text-align: center; font-weight: bold;">GENERAL SCORE</td></tr><tr><td rowspan="5" style="vertical-align: top; text-align: center; font-weight: bold;">Usefulness for ACTRIS NFs</td><td style="font-weight: bold;">CRITERIA TOTAL SCORE</td><td></td><td></td><td></td><td rowspan="5" style="text-align: center; vertical-align: middle;">50%</td></tr><tr><td style="padding-left: 1em;">No. of operation support units provided to ACTRIS NFs for quality assurance and quality control</td><td></td><td></td><td></td></tr><tr><td style="padding-left: 1em;">No. of operation support units provided to ACTRIS NFs for knowledge transfer and training</td><td></td><td></td><td></td></tr><tr><td style="padding-left: 1em;">No. of operation support units provided to ACTRIS NFs for Improvement of measurement and data processing methodologies</td><td></td><td></td><td></td></tr><tr><td style="padding-left: 1em;">Average score of satisfaction received from NFs<br><i>Including utility, fairness and timeliness of the activities for operation support</i></td><td></td><td></td><td></td></tr><tr><td rowspan="4" style="vertical-align: top; text-align: center; font-weight: bold;">Usefulness for ACTRIS users</td><td style="font-weight: bold;">CRITERIA TOTAL SCORE</td><td></td><td></td><td></td><td rowspan="4" style="text-align: center; vertical-align: middle;">20%</td></tr><tr><td style="padding-left: 1em;">No. of service units provided to ACTRIS users for quality assurance and quality control</td><td></td><td></td><td></td></tr><tr><td style="padding-left: 1em;">No. of service units provided to ACTRIS users for knowledge transfer and training</td><td></td><td></td><td></td></tr><tr><td style="padding-left: 1em;">No. of service units provided to ACTRIS users for improvement of measurement and data processing methodologies</td><td></td><td></td><td></td></tr></tbody></table>

<footnote n="1">¹ With regard to the planned and approved values</footnote>
Section 5 – Centre for Cloud In Situ Measurements

<table><tbody><tr><td></td><td>Average score of satisfaction received from ACTRIS users<br/>Including utility, fairness and timeliness of the services performed</td><td></td><td></td><td></td></tr><tr><td rowspan="4">Impact on science &amp;<br/>technology</td><td>CRITERIA TOTAL SCORE</td><td></td><td></td><td rowspan="4">20%</td></tr><tr><td>No. of new technological products, methods and algorithms developed / improved</td><td></td><td></td><td></td></tr><tr><td>No. of peer-review CF-related papers published</td><td></td><td></td><td></td></tr><tr><td>No. of CF-related communications at scientific conferences/workshops</td><td></td><td></td><td></td></tr><tr><td rowspan="4">Integration into ACTRIS</td><td>No. of CF-related patents promoted</td><td></td><td></td><td></td></tr><tr><td>CRITERIA TOTAL SCORE</td><td></td><td></td><td rowspan="4">10%</td></tr><tr><td>No. of participations to ACTRIS committees and boards</td><td></td><td></td><td></td></tr><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 DC for the contribution to documentation and traceability of data products</td><td></td><td></td><td></td></tr><tr><td></td><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></tbody></table>
Section 5 – Centre for Cloud In Situ Measurements

<table><tbody><tr><td colspan="2">Average score of satisfaction received from ACTRIS users<br/>Including utility, fairness and timeliness of the services performed</td><td></td><td></td><td></td></tr><tr><td rowspan="4">Impact on science &amp;<br/>technology</td><td>CRITERIA TOTAL SCORE</td><td></td><td></td><td>20%</td></tr><tr><td>No. of new technological products, methods and algorithms developed / improved</td><td></td><td></td><td></td></tr><tr><td>No. of peer-review CF-related papers published</td><td></td><td></td><td></td></tr><tr><td>No. of CF-related communications at scientific conferences/workshops</td><td></td><td></td><td></td></tr><tr><td rowspan="4">Integration into ACTRIS</td><td>No. of CF-related patents promoted</td><td></td><td></td><td></td></tr><tr><td>CRITERIA TOTAL SCORE</td><td></td><td></td><td>10%</td></tr><tr><td>No. of participations to ACTRIS committees and boards</td><td></td><td></td><td></td></tr><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></td><td>Average score of satisfaction received from ACTRIS DC for the contribution to documentation and traceability of data products</td><td></td><td></td><td></td></tr><tr><td></td><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></tbody></table>
Glossary

**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 simulation chambers and laboratories.

**Remote sensing** - measured air and instrument are not at the same location and not in physical contact. In the context of ACTRIS, passive (radiometer) and active atmospheric remote-sensing techniques<fnref n="2" /> (lidar, radar) for the observation of aerosols, clouds, and trace gases are applied at observational sites or on mobile surface-based and airborne platforms.

**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.

○ **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.

○ 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 syntheses 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 hosting the ACTRIS data portal.

**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 the 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 campaign basis and delivering dedicated data to the Data Centre.

**ACTRIS General Assembly (GA)** - a council of ministry- and funding organization representatives of ACTRIS members after 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.

<footnote n="2">² In contrast to remote sensing of the Earth's surface (terrestrial and oceanic remote sensing), which is typically done from satellite or aircraft, atmospheric remote sensing is performed from satellite-borne and airborne as well as from surface-based platforms. In ACTRIS, mainly surface-based remote observations are carried out.</footnote>
Glossary

**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 simulation chambers and laboratories.

**Remote sensing** - measured air and instrument are not at the same location and not in physical contact. In the context of ACTRIS, passive (radiometer) and active atmospheric remote-sensing techniques<fnref n="2" /> (lidar, radar) for the observation of aerosols, clouds, and trace gases are applied at observational sites or on mobile surface-based and airborne platforms.

**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.

○ **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.

○ 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 syntheses 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 hosting the ACTRIS data portal.

**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 the 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 campaign basis and delivering dedicated data to the Data Centre.

**ACTRIS General Assembly (GA)** - a council of ministry- and funding organization representatives of ACTRIS members after 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.

<footnote n="2">² In contrast to remote sensing of the Earth's surface (terrestrial and oceanic remote sensing), which is typically done from satellite or aircraft, atmospheric remote sensing is performed from satellite-borne and airborne as well as from surface-based platforms. In ACTRIS, mainly surface-based remote observations are carried out.</footnote>
**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="3" />.

**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.

**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, in the ideal case SI units.

**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.

**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.

<footnote n="3">³The 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 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](#).

**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.

**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, in the ideal case SI units.

**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.

**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.

<footnote n="3">³The 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>
Reference documents

ACTRIS (2011-2017): Measurement Guidelines and Standard Operation Procedures available at: http://actris-nilu.no/Content/SOP).

ACTRIS-PPP proposal

ACTRIS Stakeholders Handbook 2017

ACTRIS Science Case document

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

Baseline document for the Concepts of ACTRIS Central Facilities

Technical concepts and requirements for ACTRIS Exploratory Platforms

Technical concepts and requirements for ACTRIS Observational Platforms

Boulter, J. E., Cziczo, D. J., Middlebrook, A. M., Thomson, D. S., and Murphy, D. M.: Design and performance of a pumped counterflow virtual impactor, Aerosol. Sci. Technol., 40, 969–976, doi:10.1080/02786820600840984, 2006.

Cziczo, D. J., Stetzer, O., Worringen, A., Ebert, M., Weinbruch, S., Kamphus, M., Gallavardin, S. J., Curtius, J., Borrmann, S., Froyd, K. D., Mertes, S., Möhler, O., and Lohmann, U.: Inadvertent climate modification due to anthropogenic lead, Nat. Geosci., 2, 333–336, doi:10.1038/NGEO499, 2009.

Hiranuma, N., O. Möhler, G. Kulkarni, M. Schnaiter, S. Vogt, P. Vochezer, E. Järvinen, R. Wagner, D. M. Bell, J. Wilson, A. Zelenyuk, and D. J. Cziczo (2016), Development and characterization of an ice-selecting pumped counterflow virtual impactor (IS-PCVI) to study ice crystal residuals, Atmos. Meas. Tech., 9(8), 3817–3836.

Lloyd, G., Choularton, T. W., Bower, K. N., Gallagher, M. W., Connolly, P. J., Flynn, M., Farrington, R., Crosier, J., Schlenczek, O., Fugal, J., and Henneberger, J.: The origins of ice crystals measured in mixed-phase clouds at the high-alpine site Jungfraujoch, Atmos. Chem. Phys., 15, 12953–12969, https://doi.org/10.5194/acp-15-12953-2015, 2015.

Mertes, S., Schwarzenböck, A., Laj, P., Wobrock, W., Pichon, J. M., Orsi, G., and Heintzenberg, J.: Changes of cloud microphysical properties during the transition from supercooled to mixed-phase conditions during CIME, Atmos. Res., 58, 267–294, doi:10.1016/S0169-8095(01)00095-3, 2001.

Noone, K., Ogren, J. A., Heintzenberg, J., Charlson, R. J., and Covert, D. S.: Design and calibration of a counterflow virtual impactor for sampling of atmospheric fog and cloud droplets, Aerosol Sci. Technol., 8, 235–244, doi:10.1080/02786828808959186, 1988.

Twohy, C. H., Schanot, A. J., and Cooper, W. A.: Measurement of condensed water content in liquid and ice clouds using an airborne counterflow virtual impactor, J. Atmos. Oceanic Technol., 14, 197–202, doi:10.1175/1520-0426(1997)014<0197:MOCWCI>2.0.CO;2, 1997.

Worringen, A., Kandler, K., Benker, N., Dirsch, T., Mertes, S., Schenk, L., Kästner, U., Frank, F., Nillius, B., Bundke, U., Rose, D., Curtius, J., Kupiszewski, P., Weingartner, E., Vochezer, P., Schneider, J., Schmidt, S., Weinbruch, S., and Ebert, M.: Single particle characterization of ice-nucleating particles and ice particle residuals sampled by three different techniques, Atmos. Chem. Phys., 15, 4161–4178, doi:10.5194/acp-15-4161-2015, 2015.
Reference documents

ACTRIS (2011-2017): Measurement Guidelines and Standard Operation Procedures available at: http://actris-nilu.no/Content/SOP).

ACTRIS-PPP proposal

ACTRIS Stakeholders Handbook 2017

ACTRIS Science Case document

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

Baseline document for the Concepts of ACTRIS Central Facilities

Technical concepts and requirements for ACTRIS Exploratory Platforms

Technical concepts and requirements for ACTRIS Observational Platforms

Boulter, J. E., Cziczo, D. J., Middlebrook, A. M., Thomson, D. S., and Murphy, D. M.: Design and performance of a pumped counterflow virtual impactor, Aerosol. Sci. Technol., 40, 969–976, doi:10.1080/02786820600840984, 2006.

Cziczo, D. J., Stetzer, O., Worringen, A., Ebert, M., Weinbruch, S., Kamphus, M., Gallavardin, S. J., Curtius, J., Borrmann, S., Froyd, K. D., Mertes, S., Möhler, O., and Lohmann, U.: Inadvertent climate modification due to anthropogenic lead, Nat. Geosci., 2, 333–336, doi:10.1038/NGEO499, 2009.

Hiranuma, N., O. Möhler, G. Kulkarni, M. Schnaiter, S. Vogt, P. Vochezer, E. Järvinen, R. Wagner, D. M. Bell, J. Wilson, A. Zelenyuk, and D. J. Cziczo (2016), Development and characterization of an ice-selecting pumped counterflow virtual impactor (IS-PCVI) to study ice crystal residuals, Atmos. Meas. Tech., 9(8), 3817–3836.

Lloyd, G., Choularton, T. W., Bower, K. N., Gallagher, M. W., Connolly, P. J., Flynn, M., Farrington, R., Crosier, J., Schlenczek, O., Fugal, J., and Henneberger, J.: The origins of ice crystals measured in mixed-phase clouds at the high-alpine site Jungfraujoch, Atmos. Chem. Phys., 15, 12953–12969, https://doi.org/10.5194/acp-15-12953-2015, 2015.

Mertes, S., Schwarzenböck, A., Laj, P., Wobrock, W., Pichon, J. M., Orsi, G., and Heintzenberg, J.: Changes of cloud microphysical properties during the transition from supercooled to mixed-phase conditions during CIME, Atmos. Res., 58, 267–294, doi:10.1016/S0169-8095(01)00095-3, 2001.

Noone, K., Ogren, J. A., Heintzenberg, J., Charlson, R. J., and Covert, D. S.: Design and calibration of a counterflow virtual impactor for sampling of atmospheric fog and cloud droplets, Aerosol Sci. Technol., 8, 235–244, doi:10.1080/02786828808959186, 1988.

Twohy, C. H., Schanot, A. J., and Cooper, W. A.: Measurement of condensed water content in liquid and ice clouds using an airborne counterflow virtual impactor, J. Atmos. Oceanic Technol., 14, 197–202, doi:10.1175/1520-0426(1997)014<0197:MOCWCI>2.0.CO;2, 1997.

Worringen, A., Kandler, K., Benker, N., Dirsch, T., Mertes, S., Schenk, L., Kästner, U., Frank, F., Nillius, B., Bundke, U., Rose, D., Curtius, J., Kupiszewski, P., Weingartner, E., Vochezer, P., Schneider, J., Schmidt, S., Weinbruch, S., and Ebert, M.: Single particle characterization of ice-nucleating particles and ice particle residuals sampled by three different techniques, Atmos. Chem. Phys., 15, 4161–4178, doi:10.5194/acp-15-4161-2015, 2015.
# Annex: Provision of the operation support

## Scheduled support

CIS will arrange so-called scheduled support which will be mandatory for the cloud in situ NFs to participate. The schedule will be announced on the CIS and ACTRIS websites, and communicated with the PIs of CIS measurement techniques operated at the NF. A web tool should be developed as part of the CIS website to allow easy and fast registration to the scheduled activities. This support should be managed by the lead unit of the CIS.

QA/QC activities like round robin or intercomparison experiments which are open to all users, should be announced on the CIS web-page at least 3 months before the event, with number of potential participants and conditions for contribution. Applications should be selected by the CIS units in one of the regular teleconferences of the CIS. Results of these activities should be made openly available on the CIS webpage.

<table><thead><tr><td>Scheduled support</td><td>Measurement technique</td><td>Frequency</td></tr></thead><tbody><tr><td>Direct calibration to fixed (at TC unit) or mobile (provided by TC unit) reference instrument or transfer standards (round robin)</td><td>Integrating cloud probes<br>Cloud droplet probes<br>Cloud ice probes<br>INP instruments<br>Cloud water chemical analysis</td><td>Every few years (may be instrument specific)</td></tr><tr><td>Instrument/method intercomparison campaigns at observational or exploratory platforms</td><td>Integrating cloud probes<br>Cloud droplet probes<br>Cloud ice probes<br>INP instruments<br>Cloud water chemical analysis</td><td>Every few years (may be instrument specific)</td></tr><tr><td>Expert visit and audits to NFs to check QA/QC procedures and measurement guidelines, implement software tools, test design, performance and operation of inlets and sampling systems.</td><td>all</td><td>Once per year</td></tr><tr><td>Training sessions or workshops for operators and scientist</td><td>All, both established/standardized and new instruments</td><td>Once per year at respective unit</td></tr><tr><td>Workshop on scientific aspects, instruments, methods, software, data systems, new developments.</td><td>All instruments, software, data systems, new developments, ...</td><td>Once per year, open to users</td></tr></tbody></table>
# Annex: Provision of the operation support

## Scheduled support

CIS will arrange so-called scheduled support which will be mandatory for the cloud in situ NFs to participate. The schedule will be announced on the CIS and ACTRIS websites, and communicated with the PIs of CIS measurement techniques operated at the NF. A web tool should be developed as part of the CIS website to allow easy and fast registration to the scheduled activities. This support should be managed by the lead unit of the CIS.

QA/QC activities like round robin or intercomparison experiments which are open to all users, should be announced on the CIS web-page at least 3 months before the event, with number of potential participants and conditions for contribution. Applications should be selected by the CIS units in one of the regular teleconferences of the CIS. Results of these activities should be made openly available on the CIS webpage.

<table><thead><tr><td>Scheduled support</td><td>Measurement technique</td><td>Frequency</td></tr></thead><tbody><tr><td>Direct calibration to fixed (at TC unit) or mobile (provided by TC unit) reference instrument or transfer standards (round robin)</td><td>Integrating cloud probes<br>Cloud droplet probes<br>Cloud ice probes<br>INP instruments<br>Cloud water chemical analysis</td><td>Every few years (may be instrument specific)</td></tr><tr><td>Instrument/method intercomparison campaigns at observational or exploratory platforms</td><td>Integrating cloud probes<br>Cloud droplet probes<br>Cloud ice probes<br>INP instruments<br>Cloud water chemical analysis</td><td>Every few years (may be instrument specific)</td></tr><tr><td>Expert visit and audits to NFs to check QA/QC procedures and measurement guidelines, implement software tools, test design, performance and operation of inlets and sampling systems.</td><td>all</td><td>Once per year</td></tr><tr><td>Training sessions or workshops for operators and scientist</td><td>All, both established/standardized and new instruments</td><td>Once per year at respective unit</td></tr><tr><td>Workshop on scientific aspects, instruments, methods, software, data systems, new developments.</td><td>All instruments, software, data systems, new developments, ...</td><td>Once per year, open to users</td></tr></tbody></table>
**Operation support on request**

Cloud in situ NFs may face difficulties in the implementation or operation of instruments, and CIS should put in place appropriate support. This support should be offered on request. Requests for support should be addressed by the NFs to CIS, through direct communication between the PIs and the CIS Management Board. CIS should put in place a suitable framework for exchanging relevant information and documentation with the PIs, to prepare the operation support. CIS Management Board is responsible to prioritize and decide about the actual support to be offered ( timeline, responsible unit, and specific conditions).
**Operation support on request**

Cloud in situ NFs may face difficulties in the implementation or operation of instruments, and CIS should put in place appropriate support. This support should be offered on request. Requests for support should be addressed by the NFs to CIS, through direct communication between the PIs and the CIS Management Board. CIS should put in place a suitable framework for exchanging relevant information and documentation with the PIs, to prepare the operation support. CIS Management Board is responsible to prioritize and decide about the actual support to be offered ( timeline, responsible unit, and specific conditions).
Section 6

Concept of the Centre for Cloud Remote Sensing
(CCRES)

ACTRIS PPP WP 4 Task 4.1

21.2.2018

Public
Section 6

Concept of the Centre for Cloud Remote Sensing
(CCRES)

ACTRIS PPP WP 4 Task 4.1

21.2.2018

Public
Contents

<table><tr><td>1</td><td>Purpose of the document</td><td>4</td></tr><tr><td>2</td><td>Description and role of the Centre for Cloud Remote Sensing</td><td>4</td></tr><tr><td>2.1</td><td>Framework</td><td>4</td></tr><tr><td>2.2</td><td>Scientific relevance</td><td>4</td></tr><tr><td>2.3</td><td>Mission</td><td>5</td></tr><tr><td>3</td><td>Operation support provided to ACTRIS National Facilities</td><td>6</td></tr><tr><td>3.1</td><td>Instruments covered by the Centre for Cloud Remote Sensing, and related ACTRIS variables</td><td>6</td></tr><tr><td>3.1.1</td><td>Millimetre-wave Doppler Cloud Radar</td><td>6</td></tr><tr><td>3.1.2</td><td>Microwave radiometer</td><td>7</td></tr><tr><td>3.1.3</td><td>Doppler Wind Lidar</td><td>7</td></tr><tr><td>3.2</td><td>Estimation of the need</td><td>7</td></tr><tr><td>3.3</td><td>Timeline for implementation of the mandatory operation support</td><td>8</td></tr><tr><td>3.4</td><td>Operation support for quality assurance and quality control</td><td>9</td></tr><tr><td>3.4.1</td><td>Definition and establishment of standard operation procedures</td><td>9</td></tr><tr><td>3.4.2</td><td>Development and provision of instrument-specific calibration</td><td>10</td></tr><tr><td>3.4.3</td><td>Definition of measurement quality-assurance criteria and procedures</td><td>12</td></tr><tr><td>3.4.4</td><td>Development and provision of in-house check-up tools</td><td>13</td></tr><tr><td>3.4.5</td><td>Development of data evaluation procedures and plausibility test</td><td>13</td></tr><tr><td>3.4.6</td><td>Realization of observational site performance audits with reference samples or mobile systems</td><td>14</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>15</td></tr><tr><td>3.4.8</td><td>Contribution to documentation and traceability of level 0 to level 3 data products</td><td>15</td></tr><tr><td>3.4.9</td><td>Contribution to CEN, ISO, or similar standardization activities</td><td>15</td></tr><tr><td>3.5</td><td>Operation support for knowledge transfer and training</td><td>16</td></tr><tr><td>3.5.1</td><td>Training of operators and scientists</td><td>16</td></tr><tr><td>3.5.2</td><td>Consultancy for setting-up new observational or exploratory platforms and new instruments at the NFs</td><td>16</td></tr><tr><td>3.6</td><td>Operation support for improvement of measurement methodologies</td><td>16</td></tr><tr><td>3.6.1</td><td>Testing of new measurement instruments and procedures</td><td>16</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>17</td></tr><tr><td>3.6.3</td><td>Development of new technological products and methods</td><td>17</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>17</td></tr><tr><td>3.7</td><td>Provision of the operation support</td><td>18</td></tr></table>
Contents

<table><tr><td>1</td><td>Purpose of the document</td><td>4</td></tr><tr><td>2</td><td>Description and role of the Centre for Cloud Remote Sensing</td><td>4</td></tr><tr><td>2.1</td><td>Framework</td><td>4</td></tr><tr><td>2.2</td><td>Scientific relevance</td><td>4</td></tr><tr><td>2.3</td><td>Mission</td><td>5</td></tr><tr><td>3</td><td>Operation support provided to ACTRIS National Facilities</td><td>6</td></tr><tr><td>3.1</td><td>Instruments covered by the Centre for Cloud Remote Sensing, and related ACTRIS variables</td><td>6</td></tr><tr><td>3.1.1</td><td>Millimetre-wave Doppler Cloud Radar</td><td>6</td></tr><tr><td>3.1.2</td><td>Microwave radiometer</td><td>7</td></tr><tr><td>3.1.3</td><td>Doppler Wind Lidar</td><td>7</td></tr><tr><td>3.2</td><td>Estimation of the need</td><td>7</td></tr><tr><td>3.3</td><td>Timeline for implementation of the mandatory operation support</td><td>8</td></tr><tr><td>3.4</td><td>Operation support for quality assurance and quality control</td><td>9</td></tr><tr><td>3.4.1</td><td>Definition and establishment of standard operation procedures</td><td>9</td></tr><tr><td>3.4.2</td><td>Development and provision of instrument-specific calibration</td><td>10</td></tr><tr><td>3.4.3</td><td>Definition of measurement quality-assurance criteria and procedures</td><td>12</td></tr><tr><td>3.4.4</td><td>Development and provision of in-house check-up tools</td><td>13</td></tr><tr><td>3.4.5</td><td>Development of data evaluation procedures and plausibility test</td><td>13</td></tr><tr><td>3.4.6</td><td>Realization of observational site performance audits with reference samples or mobile systems</td><td>14</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>15</td></tr><tr><td>3.4.8</td><td>Contribution to documentation and traceability of level 0 to level 3 data products</td><td>15</td></tr><tr><td>3.4.9</td><td>Contribution to CEN, ISO, or similar standardization activities</td><td>15</td></tr><tr><td>3.5</td><td>Operation support for knowledge transfer and training</td><td>16</td></tr><tr><td>3.5.1</td><td>Training of operators and scientists</td><td>16</td></tr><tr><td>3.5.2</td><td>Consultancy for setting-up new observational or exploratory platforms and new instruments at the NFs</td><td>16</td></tr><tr><td>3.6</td><td>Operation support for improvement of measurement methodologies</td><td>16</td></tr><tr><td>3.6.1</td><td>Testing of new measurement instruments and procedures</td><td>16</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>17</td></tr><tr><td>3.6.3</td><td>Development of new technological products and methods</td><td>17</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>17</td></tr><tr><td>3.7</td><td>Provision of the operation support</td><td>18</td></tr></table>
<table><tr><td>3.7.1 Scheduled support</td><td>18</td></tr><tr><td>3.7.2 Operation support on request</td><td>19</td></tr><tr><td>4 Services provided to ACTRIS users</td><td>20</td></tr><tr><td>4.1 Estimation of the need</td><td>20</td></tr><tr><td>4.2 Provision of measurement quality assurance and quality control procedures and tools</td><td>21</td></tr><tr><td>4.3 Instrument-specific calibration</td><td>21</td></tr><tr><td>4.4 Knowledge transfer and operator training</td><td>21</td></tr><tr><td>4.5 Improvement of measurement and retrieval methodologies for aerosols, clouds, and reactive trace gases</td><td>21</td></tr><tr><td>5 Governance and management structure of the Centre for Cloud Remote Sensing</td><td>22</td></tr><tr><td>6 Requirements for the Centre for Cloud Remote Sensing</td><td>22</td></tr><tr><td>6.1 General requirements</td><td>22</td></tr><tr><td>6.2 Technical requirements</td><td>22</td></tr><tr><td>6.2.1 Facilities</td><td>22</td></tr><tr><td>6.2.2 Human resources</td><td>23</td></tr><tr><td>7 Selection of the Centre for Cloud Remote Sensing site(s)</td><td>24</td></tr><tr><td>8 Obligations of the Centre for Cloud Remote Sensing</td><td>24</td></tr><tr><td>8.1 General obligations</td><td>24</td></tr><tr><td>8.2 Technical obligations</td><td>24</td></tr><tr><td>8.2.1 Technical obligations in relation with the ACTRIS National Facilities</td><td>24</td></tr><tr><td>8.2.2 Technical obligations in relation with the ACTRIS Data Centre</td><td>26</td></tr><tr><td>8.2.3 Technical obligations in relation with Centre for Aerosol Remote Sensing)</td><td>27</td></tr><tr><td>8.2.4 Technical obligations in relation with the ACTRIS users</td><td>27</td></tr><tr><td>8.3 Evaluation of the activity of the Centre for Cloud Remote Sensing</td><td>27</td></tr><tr><td>Glossary</td><td>28</td></tr><tr><td>Reference documents</td><td>30</td></tr></table>
<table><tr><td>3.7.1 Scheduled support</td><td>18</td></tr><tr><td>3.7.2 Operation support on request</td><td>19</td></tr><tr><td>4 Services provided to ACTRIS users</td><td>20</td></tr><tr><td>4.1 Estimation of the need</td><td>20</td></tr><tr><td>4.2 Provision of measurement quality assurance and quality control procedures and tools</td><td>21</td></tr><tr><td>4.3 Instrument-specific calibration</td><td>21</td></tr><tr><td>4.4 Knowledge transfer and operator training</td><td>21</td></tr><tr><td>4.5 Improvement of measurement and retrieval methodologies for aerosols, clouds, and reactive trace gases</td><td>21</td></tr><tr><td>5 Governance and management structure of the Centre for Cloud Remote Sensing</td><td>22</td></tr><tr><td>6 Requirements for the Centre for Cloud Remote Sensing</td><td>22</td></tr><tr><td>6.1 General requirements</td><td>22</td></tr><tr><td>6.2 Technical requirements</td><td>22</td></tr><tr><td>6.2.1 Facilities</td><td>22</td></tr><tr><td>6.2.2 Human resources</td><td>23</td></tr><tr><td>7 Selection of the Centre for Cloud Remote Sensing site(s)</td><td>24</td></tr><tr><td>8 Obligations of the Centre for Cloud Remote Sensing</td><td>24</td></tr><tr><td>8.1 General obligations</td><td>24</td></tr><tr><td>8.2 Technical obligations</td><td>24</td></tr><tr><td>8.2.1 Technical obligations in relation with the ACTRIS National Facilities</td><td>24</td></tr><tr><td>8.2.2 Technical obligations in relation with the ACTRIS Data Centre</td><td>26</td></tr><tr><td>8.2.3 Technical obligations in relation with Centre for Aerosol Remote Sensing)</td><td>27</td></tr><tr><td>8.2.4 Technical obligations in relation with the ACTRIS users</td><td>27</td></tr><tr><td>8.3 Evaluation of the activity of the Centre for Cloud Remote Sensing</td><td>27</td></tr><tr><td>Glossary</td><td>28</td></tr><tr><td>Reference documents</td><td>30</td></tr></table>
# 1 Purpose of the document

This document describes the relevance, mission, requirements and obligations of the ACTRIS Centre for
Cloud Remote Sensing.

# 2 Description and role of the Centre for Cloud Remote Sensing

## 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 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 Cloud Remote Sensing is one of the six ACTRIS Topical Centres 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

Cloud processes are important fields of scientific research because of their role in meteorology, climate change at the global scale, and climate variability at the regional scale. Additionally, clouds and cloud-related weather conditions can have significant impact on human activities (e.g. water resources, transport, renewable energies).

Clouds as a major component of meteorology and climate, cannot be studied independently from boundary layer processes, atmospheric dynamics, including radiative, microphysical, thermodynamical, dynamical and turbulent processes. Hence cloud studies require knowledge of essential variables such as cloud geometrical boundaries, cloud water content, cloud droplet effective radius, in-cloud dynamics such as droplet velocity, but also temperature, humidity, wind profiles, and the surface energy budget.

Scientific research questions and societal applications linked to cloud and boundary-layer processes are numerous. Detailed and high-quality observations of cloud properties, atmospheric thermodynamic and dynamic variables are essential for the following applications:

* Studies of cloud microphysical, radiative, dynamic and thermodynamic processes, including cloud-aerosol interactions

* Cal/Val activities to support satellite-based global-scale observations
# 1 Purpose of the document

This document describes the relevance, mission, requirements and obligations of the ACTRIS Centre for
Cloud Remote Sensing.

# 2 Description and role of the Centre for Cloud Remote Sensing

## 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 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 Cloud Remote Sensing is one of the six ACTRIS Topical Centres 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

Cloud processes are important fields of scientific research because of their role in meteorology, climate change at the global scale, and climate variability at the regional scale. Additionally, clouds and cloud-related weather conditions can have significant impact on human activities (e.g. water resources, transport, renewable energies).

Clouds as a major component of meteorology and climate, cannot be studied independently from boundary layer processes, atmospheric dynamics, including radiative, microphysical, thermodynamical, dynamical and turbulent processes. Hence cloud studies require knowledge of essential variables such as cloud geometrical boundaries, cloud water content, cloud droplet effective radius, in-cloud dynamics such as droplet velocity, but also temperature, humidity, wind profiles, and the surface energy budget.

Scientific research questions and societal applications linked to cloud and boundary-layer processes are numerous. Detailed and high-quality observations of cloud properties, atmospheric thermodynamic and dynamic variables are essential for the following applications:

* Studies of cloud microphysical, radiative, dynamic and thermodynamic processes, including cloud-aerosol interactions

* Cal/Val activities to support satellite-based global-scale observations
* Numerical weather prediction, severe weather (model verification, data assimilation, development of new parametrizations)

* Climate and climate change studies and modelling (climate variability studies, model verification)

* Air quality and green-house gas modelling (boundary layer observation and prediction)

* Prediction of weather conditions (fog, clouds, precipitation) that impact human activities (e.g. airport traffic planning, renewable energy production)

Expert knowledge on measurements and observations pertaining to clouds and boundary layer processes are also necessary to

* Improve the quality of operational data provision for applied services (e.g. Copernicus program),

* Support Instrument / Measurement industry (standard procedures, new technology).

Currently, in the ACTRIS framework, deriving the relevant parameters rely on measurements based on Doppler millimetre-band radars, automatic low power lidars, microwave radiometers, and Doppler lidars. Requirements for ACTRIS observational platforms contributing to cloud remote-sensing observations are defined in a specific document. Each required instrument must be carefully calibrated before the relevant cloud parameters can be derived. In a network all instruments should be calibrated in a consistent and traceable manner so that retrieved parameters can be derived on a comparable scale and with a known uncertainty. Common algorithms to be applied to all network measurements are also a must to generate network-wide consistent geophysical parameters.

The European FP5 CloudNet program and following activities in ACTRIS-1 and ACTRIS-2 generated a robust set of algorithms that allow the radar-lidar-radiometer synergy to be exploited to retrieve cloud geometrical and microphysical properties. These programs did not however implement consistent calibration methods for Doppler Cloud Radars, hence their calibration uncertainties are not well quantified.

The EG-CLIMET and TOPROF COST actions were instrumental in developing operation and calibration procedures and recommendations for automatic low power lidars and ceilometers, microwave radiometers and Doppler Lidars.

ACTRIS-RI must provide a framework for operation, calibration and data quality monitoring procedures to be implemented network-wide for all pre-cited instruments.

## 2.3 Mission

The mission of the Centre for Cloud Remote Sensing (CCRES) is to offer operational support to ACTRIS National Facilities operating Cloud remote sensing instrumentation, namely to Doppler W- or Ka-band Radars for cloud profiling, Microwave Radiometers for temperature and humidity profiling, and Doppler Lidars for wind profiling. The CCRES should also provide support for automatic low power lidars and ceilometers used for cloud profiling purposes.

Additionally, the Centre for Cloud Remote Sensing should offer specialized services for the pre-cited instruments and related ACTRIS variables, to ACTRIS users of various types: academia, business, industry and public services.
* Numerical weather prediction, severe weather (model verification, data assimilation, development of new parametrizations)

* Climate and climate change studies and modelling (climate variability studies, model verification)

* Air quality and green-house gas modelling (boundary layer observation and prediction)

* Prediction of weather conditions (fog, clouds, precipitation) that impact human activities (e.g. airport traffic planning, renewable energy production)

Expert knowledge on measurements and observations pertaining to clouds and boundary layer processes are also necessary to

* Improve the quality of operational data provision for applied services (e.g. Copernicus program),

* Support Instrument / Measurement industry (standard procedures, new technology).

Currently, in the ACTRIS framework, deriving the relevant parameters rely on measurements based on Doppler millimetre-band radars, automatic low power lidars, microwave radiometers, and Doppler lidars. Requirements for ACTRIS observational platforms contributing to cloud remote-sensing observations are defined in a specific document. Each required instrument must be carefully calibrated before the relevant cloud parameters can be derived. In a network all instruments should be calibrated in a consistent and traceable manner so that retrieved parameters can be derived on a comparable scale and with a known uncertainty. Common algorithms to be applied to all network measurements are also a must to generate network-wide consistent geophysical parameters.

The European FP5 CloudNet program and following activities in ACTRIS-1 and ACTRIS-2 generated a robust set of algorithms that allow the radar-lidar-radiometer synergy to be exploited to retrieve cloud geometrical and microphysical properties. These programs did not however implement consistent calibration methods for Doppler Cloud Radars, hence their calibration uncertainties are not well quantified.

The EG-CLIMET and TOPROF COST actions were instrumental in developing operation and calibration procedures and recommendations for automatic low power lidars and ceilometers, microwave radiometers and Doppler Lidars.

ACTRIS-RI must provide a framework for operation, calibration and data quality monitoring procedures to be implemented network-wide for all pre-cited instruments.

## 2.3 Mission

The mission of the Centre for Cloud Remote Sensing (CCRES) is to offer operational support to ACTRIS National Facilities operating Cloud remote sensing instrumentation, namely to Doppler W- or Ka-band Radars for cloud profiling, Microwave Radiometers for temperature and humidity profiling, and Doppler Lidars for wind profiling. The CCRES should also provide support for automatic low power lidars and ceilometers used for cloud profiling purposes.

Additionally, the Centre for Cloud Remote Sensing should offer specialized services for the pre-cited 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 key services and operation support provided by the Centre for Cloud Remote Sensing should be: 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 users, and c) improvements of measurement methodologies for clouds and related variables of interest. This TC should provide (1) remote support to NFs (i.e. support that does not require physical access by NFs), related to procedures and performance evaluation; (2) support based on physical access to ensure network-wide calibration and site evaluations when required; (3) training and opportunities for knowledge sharing. During the implementation phase, 65%, 25%, and 10% of the human resources of the TC should be devoted to remote support, physical access, and training, respectively. During the operational phase, these numbers could evolve to 60%, 30%, and 10%.

The Centre for Cloud Remote Sensing 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 TC should contribute to expert collaboration networks.

### 3.1 Instruments covered by the Centre for Cloud Remote Sensing, and related ACTRIS variables

The Centre for Cloud Remote Sensing should deliver a service for Doppler W- or Ka-band Radars for cloud profiling, Microwave Radiometers for temperature/humidity profiling and liquid water path, and Doppler Lidars for wind profiling. The Centre should also provide support for automatic low power lidars and ceilometers used for cloud profiling purposes. These four instruments are necessary to derive vertical profiles of cloud macrophysical and microphysical properties and related atmospheric variables based on several synergetic algorithms.

Critical issues relevant for cloud observations are instrument calibrations, continuous data quality monitoring as well as harmonized data processing. These points must be addressed to derive network-wide consistent atmospheric quantities, such as cloud classification, liquid water content profiles as well as temperature and humidity profiles.

#### 3.1.1 Millimetre-wave Doppler Cloud Radar

A Doppler Cloud Radar (denoted DCR) is an active remote sensing instrument operating in the millimetre wavelength range and providing vertical profiles of reflectivity and Doppler velocity of hydrometeors. The ACTRIS Cloud remote sensing network is composed of different types of DCRs:

* Vertically pointing DCRs at 35 GHz (e.g. MIRA 36 by METEK);

* Scanning DCRs at 35 GHz (e.g. some models of MIRA 35/36 by METEK);

* Vertically pointing DCRs at 94GHz (e.g. 94 GHz BASTA by MODEM; RPG-FMCW-94 by RPG);

* Scanning DCRs at 94GHz (e.g. 94 GHz BASTA-mini by MODEM).
## 3 Operation support provided to ACTRIS National Facilities

The key services and operation support provided by the Centre for Cloud Remote Sensing should be: 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 users, and c) improvements of measurement methodologies for clouds and related variables of interest. This TC should provide (1) remote support to NFs (i.e. support that does not require physical access by NFs), related to procedures and performance evaluation; (2) support based on physical access to ensure network-wide calibration and site evaluations when required; (3) training and opportunities for knowledge sharing. During the implementation phase, 65%, 25%, and 10% of the human resources of the TC should be devoted to remote support, physical access, and training, respectively. During the operational phase, these numbers could evolve to 60%, 30%, and 10%.

The Centre for Cloud Remote Sensing 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 TC should contribute to expert collaboration networks.

### 3.1 Instruments covered by the Centre for Cloud Remote Sensing, and related ACTRIS variables

The Centre for Cloud Remote Sensing should deliver a service for Doppler W- or Ka-band Radars for cloud profiling, Microwave Radiometers for temperature/humidity profiling and liquid water path, and Doppler Lidars for wind profiling. The Centre should also provide support for automatic low power lidars and ceilometers used for cloud profiling purposes. These four instruments are necessary to derive vertical profiles of cloud macrophysical and microphysical properties and related atmospheric variables based on several synergetic algorithms.

Critical issues relevant for cloud observations are instrument calibrations, continuous data quality monitoring as well as harmonized data processing. These points must be addressed to derive network-wide consistent atmospheric quantities, such as cloud classification, liquid water content profiles as well as temperature and humidity profiles.

#### 3.1.1 Millimetre-wave Doppler Cloud Radar

A Doppler Cloud Radar (denoted DCR) is an active remote sensing instrument operating in the millimetre wavelength range and providing vertical profiles of reflectivity and Doppler velocity of hydrometeors. The ACTRIS Cloud remote sensing network is composed of different types of DCRs:

* Vertically pointing DCRs at 35 GHz (e.g. MIRA 36 by METEK);

* Scanning DCRs at 35 GHz (e.g. some models of MIRA 35/36 by METEK);

* Vertically pointing DCRs at 94GHz (e.g. 94 GHz BASTA by MODEM; RPG-FMCW-94 by RPG);

* Scanning DCRs at 94GHz (e.g. 94 GHz BASTA-mini by MODEM).
CCRES should be able to calibrate, provide measurement and data quality assurance procedures for these four types of DCRs. Each DCR type may require particular calibration techniques (e.g. absolute calibration or cross-comparisons, using metallic or natural targets).

### 3.1.2 Microwave radiometer

Passive microwave radiometers (MWR) are used to measure several atmospheric quantities, such as the cloud liquid water path, column-integrated water vapour, as well as temperature and humidity profiles of the lower troposphere. For the TC, the liquid water path is the most important variable since it can only be measured using this technique with sufficient accuracy.

Most of the MWR within the ACTRIS Cloud remote sensing network are instruments that measure in two frequency bands (Ka-Band, 22-30 GHz) and V-Band (51-58 GHz) and have an elevation scanning capability. This is also considered as optimal setting for deriving all above mentioned parameters.

The minimum requirement within ACTRIS is a vertically pointing two channel radiometer (23/31 GHz) to measure only cloud liquid water path and integrated water vapour.

CCRES should be able to provide standard operation, calibration and quality check procedures as well as quality assurance for the MWRs of the two main manufacturers. It will provide guidelines for minimum requirements for potentially newly developed instruments.

### 3.1.3 Doppler Wind Lidar

A Doppler wind lidar (DWL) is an active remote sensing instrument that provides profiles of Doppler velocity from atmospheric tracers of the wind such as aerosol particles and cloud droplets.

The DWL operating within the ACTRIS Cloud remote sensing network are long-range (maximum range beyond 2 km) instruments operating at a wavelength of 1.5 µm, and have scanning capability enabling the provision of horizontal winds and turbulent properties throughout the full extent of the boundary layer.

CCRES should be able to provide standard operation, calibration and quality check procedures as well as quality assurance for the long-range scanning DWLs from the two main manufacturers. It will provide guidelines for minimum requirements for potentially newly developed instruments.

## 3.2 Estimation of the need

<table><thead><tr><th rowspan="3">Instrument</th><th colspan="3">Number of instruments/groups to which the TC is providing operational support</th></tr><tr><th rowspan="2">Now</th><th colspan="2">by 2025</th></tr><tr><th>Min.</th><th>Max.</th></tr></thead><tbody><tr><td>Millimetre-wave Doppler Cloud Radar</td><td>15</td><td>15</td><td>30</td></tr><tr><td>Microwave Radiometer</td><td>15</td><td>15</td><td>30</td></tr><tr><td>Doppler Wind Lidar</td><td>8</td><td>15</td><td>30</td></tr></tbody></table>
CCRES should be able to calibrate, provide measurement and data quality assurance procedures for these four types of DCRs. Each DCR type may require particular calibration techniques (e.g. absolute calibration or cross-comparisons, using metallic or natural targets).

### 3.1.2 Microwave radiometer

Passive microwave radiometers (MWR) are used to measure several atmospheric quantities, such as the cloud liquid water path, column-integrated water vapour, as well as temperature and humidity profiles of the lower troposphere. For the TC, the liquid water path is the most important variable since it can only be measured using this technique with sufficient accuracy.

Most of the MWR within the ACTRIS Cloud remote sensing network are instruments that measure in two frequency bands (Ka-Band, 22-30 GHz) and V-Band (51-58 GHz) and have an elevation scanning capability. This is also considered as optimal setting for deriving all above mentioned parameters.

The minimum requirement within ACTRIS is a vertically pointing two channel radiometer (23/31 GHz) to measure only cloud liquid water path and integrated water vapour.

CCRES should be able to provide standard operation, calibration and quality check procedures as well as quality assurance for the MWRs of the two main manufacturers. It will provide guidelines for minimum requirements for potentially newly developed instruments.

### 3.1.3 Doppler Wind Lidar

A Doppler wind lidar (DWL) is an active remote sensing instrument that provides profiles of Doppler velocity from atmospheric tracers of the wind such as aerosol particles and cloud droplets.

The DWL operating within the ACTRIS Cloud remote sensing network are long-range (maximum range beyond 2 km) instruments operating at a wavelength of 1.5 µm, and have scanning capability enabling the provision of horizontal winds and turbulent properties throughout the full extent of the boundary layer.

CCRES should be able to provide standard operation, calibration and quality check procedures as well as quality assurance for the long-range scanning DWLs from the two main manufacturers. It will provide guidelines for minimum requirements for potentially newly developed instruments.

## 3.2 Estimation of the need

<table><thead><tr><th rowspan="3">Instrument</th><th colspan="3">Number of instruments/groups to which the TC is providing operational support</th></tr><tr><th rowspan="2">Now</th><th colspan="2">by 2025</th></tr><tr><th>Min.</th><th>Max.</th></tr></thead><tbody><tr><td>Millimetre-wave Doppler Cloud Radar</td><td>15</td><td>15</td><td>30</td></tr><tr><td>Microwave Radiometer</td><td>15</td><td>15</td><td>30</td></tr><tr><td>Doppler Wind Lidar</td><td>8</td><td>15</td><td>30</td></tr></tbody></table>
## 3.3 Timeline for implementation of the mandatory operation support

Considering the ACTRIS roadmap, the CCRES should consider the following implementation plan for the mandatory operation support (including general tasks, scheduled and on request operation support:

<table><thead><tr><th>Operation support</th><th>CONCERNED INSTRUMENTS</th><th>TYPE</th><th>Preparation phase<br/>&lt; 2020</th><th>Implementation phase<br/>2020 - 2025</th><th>Operation phase<br/>&gt; 2025</th></tr></thead><tbody><tr><td>SOPs (site requirements, instrument deployment, instrument operation).</td><td>DCR, MWR, DWL</td><td>General task</td><td>Basic SOPs, based on experience from past projects</td><td>First version of ACTRIS SOP at end of Y1 of implementation phase</td><td>Continuous review of SOPs</td></tr><tr><td>Instrument-specific calibration</td><td>DCR, MWR</td><td>Scheduled</td><td>Run calibration experiments involving ACTRIS NF DCRs. Develop recommendations for all calibration types, all instruments.</td><td>Provision of calibration procedures, guidelines. Development of calibration monitoring software. Calibration intercomparisons. Calibration campaign</td><td>Updates and new</td></tr><tr><td>Measurement QA criteria &amp; procedures</td><td>DCR, MWR, DWL</td><td>General task</td><td>Basic data flagging (instrument stability) and basic maintenance schedule</td><td>Development and implementation of automatic quality checks (analysis of standard housekeeping data). Development of extended data flagging, Definition of extended maintenance schedule</td><td>Review of QA/QC methods based on experiences in implementation phase</td></tr><tr><td>In-house check-up tools</td><td>DCR, MWR, DWL</td><td>General task</td><td>Recommendation for instrument housekeeping data storage</td><td>Development codes to analyze the housekeeping parameters</td><td>Updates and new</td></tr><tr><td>Data evaluation procedures and plausibility test</td><td>DCR, MWR, DWL</td><td>General task</td><td>Evaluate plausibility ranges for DCR, MWR, DWL measurements</td><td>Development of evaluation of DCR, MWR, DWL data by using other observation methods and models</td><td>Updates and new</td></tr><tr><td>Site performance audits based on remote analysis or mobile systems</td><td></td><td>Scheduled</td><td></td><td>Development of questionnaire for site audit, and tools to review log books provided by NFs</td><td>Updates and new</td></tr><tr><td>NF / instrument performance assessment</td><td>DCR</td><td>Scheduled</td><td>Annual CCRES workshop in the framework of ACTRIS-2</td><td>Annual workshop with NFs for discussion of measurement performance, data quality and instrument issues, Performance evaluation for new NFs</td><td></td></tr><tr><td>Documentation and traceability</td><td></td><td>General task</td><td></td><td>Traceability of data products (level 0 &gt; level 3) by complete documentation of data flow and metadata</td><td></td></tr><tr><td rowspan="4">Training</td><td>DCR, MWR, DWL</td><td>Scheduled</td><td>Development of material for future training sessions.</td><td>Regular training sessions (at least once per year) on pre-defined subjects, such as calibration, training of new operators, implementation of SOPs and data quality procedures</td><td></td></tr><tr><td>DCR, MWR, DWL</td><td>Scheduled</td><td></td><td>Transfer of expertise during regular exercises to assess the performances of the NFs</td><td></td></tr><tr><td>DCR, MWR, DWL</td><td>General task</td><td></td><td>Documentation available on the CCRES website: instrument setup, QC, QA protocols, operation and optimization of the instruments and data management</td><td></td></tr><tr><td>DCR, MWR, DWL</td><td>On-request</td><td></td><td>Regular webex sessions as follow-ups of the face-to-face training (quarterly)</td><td></td></tr><tr><td>Consultancy</td><td></td><td>On-request</td><td></td><td>Upgrading of the instruments</td><td></td></tr><tr><td>Testing of new instruments and procedures</td><td></td><td>On-request</td><td></td><td>Establishment of new observing stations (site selection, specific instrument location)</td><td></td></tr><tr><td>Development of strategies to increase duty cycle</td><td>DCR</td><td>General task</td><td></td><td>Testing of prototypes against reference instruments</td><td></td></tr><tr><td>Development of new technological products and methods</td><td>DCR, MWR, DWL</td><td>General task</td><td>Monitoring of new developments</td><td>Setup of user forum to detect reasons for instrument downtimes</td><td>Continuation</td></tr><tr><td>Development of retrieval algorithms, including the exploitation of instrument synergies</td><td>DCR, MWR, DWL</td><td>General task</td><td>Review of existing algorithms</td><td>Discussion with manufacturers and operators on optimizing instrument performance</td><td></td></tr><tr><td></td><td></td><td></td><td></td><td>Review new retrieval algorithm developments (DCR and DCR + auxiliary), make recommendations for implementation by the DC</td><td>Updates and new</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
## 3.3 Timeline for implementation of the mandatory operation support

Considering the ACTRIS roadmap, the CCRES should consider the following implementation plan for the mandatory operation support (including general tasks, scheduled and on request operation support:

<table><thead><tr><th>Operation support</th><th>CONCERNED INSTRUMENTS</th><th>TYPE</th><th>Preparation phase<br/>&lt; 2020</th><th>Implementation phase<br/>2020 - 2025</th><th>Operation phase<br/>&gt; 2025</th></tr></thead><tbody><tr><td>SOPs (site requirements, instrument deployment, instrument operation).</td><td>DCR, MWR, DWL</td><td>General task</td><td>Basic SOPs, based on experience from past projects</td><td>First version of ACTRIS SOP at end of Y1 of implementation phase</td><td>Continuous review of SOPs</td></tr><tr><td>Instrument-specific calibration</td><td>DCR, MWR</td><td>Scheduled</td><td>Run calibration experiments involving ACTRIS NF DCRs. Develop recommendations for all calibration types, all instruments.</td><td>Provision of calibration procedures, guidelines. Development of calibration monitoring software. Calibration intercomparisons. Calibration campaign</td><td>Updates and new</td></tr><tr><td>Measurement QA criteria &amp; procedures</td><td>DCR, MWR, DWL</td><td>General task</td><td>Basic data flagging (instrument stability) and basic maintenance schedule</td><td>Development and implementation of automatic quality checks (analysis of standard housekeeping data). Development of extended data flagging, Definition of extended maintenance schedule</td><td>Review of QA/QC methods based on experiences in implementation phase</td></tr><tr><td>In-house check-up tools</td><td>DCR, MWR, DWL</td><td>General task</td><td>Recommendation for instrument housekeeping data storage</td><td>Development codes to analyze the housekeeping parameters</td><td>Updates and new</td></tr><tr><td>Data evaluation procedures and plausibility test</td><td>DCR, MWR, DWL</td><td>General task</td><td>Evaluate plausibility ranges for DCR, MWR, DWL measurements</td><td>Development of evaluation of DCR, MWR, DWL data by using other observation methods and models</td><td>Updates and new</td></tr><tr><td>Site performance audits based on remote analysis or mobile systems</td><td></td><td>Scheduled</td><td></td><td>Development of questionnaire for site audit, and tools to review log books provided by NFs</td><td>Updates and new</td></tr><tr><td>NF / instrument performance assessment</td><td>DCR</td><td>Scheduled</td><td>Annual CCRES workshop in the framework of ACTRIS-2</td><td>Annual workshop with NFs for discussion of measurement performance, data quality and instrument issues, Performance evaluation for new NFs</td><td></td></tr><tr><td>Documentation and traceability</td><td></td><td>General task</td><td></td><td>Traceability of data products (level 0 &gt; level 3) by complete documentation of data flow and metadata</td><td></td></tr><tr><td rowspan="4">Training</td><td>DCR, MWR, DWL</td><td>Scheduled</td><td>Development of material for future training sessions.</td><td>Regular training sessions (at least once per year) on pre-defined subjects, such as calibration, training of new operators, implementation of SOPs and data quality procedures</td><td></td></tr><tr><td>DCR, MWR, DWL</td><td>Scheduled</td><td></td><td>Transfer of expertise during regular exercises to assess the performances of the NFs</td><td></td></tr><tr><td>DCR, MWR, DWL</td><td>General task</td><td></td><td>Documentation available on the CCRES website: instrument setup, QC, QA protocols, operation and optimization of the instruments and data management</td><td></td></tr><tr><td>DCR, MWR, DWL</td><td>On-request</td><td></td><td>Regular webex sessions as follow-ups of the face-to-face training (quarterly)</td><td></td></tr><tr><td>Consultancy</td><td></td><td>On-request</td><td></td><td>Upgrading of the instruments</td><td></td></tr><tr><td>Testing of new instruments and procedures</td><td></td><td>On-request</td><td></td><td>Establishment of new observing stations (site selection, specific instrument location)</td><td></td></tr><tr><td>Development of strategies to increase duty cycle</td><td>DCR</td><td>General task</td><td></td><td>Testing of prototypes against reference instruments</td><td></td></tr><tr><td>Development of new technological products and methods</td><td>DCR, MWR, DWL</td><td>General task</td><td>Monitoring of new developments</td><td>Setup of user forum to detect reasons for instrument downtimes</td><td>Continuation</td></tr><tr><td>Development of retrieval algorithms, including the exploitation of instrument synergies</td><td>DCR, MWR, DWL</td><td>General task</td><td>Review of existing algorithms</td><td>Discussion with manufacturers and operators on optimizing instrument performance</td><td></td></tr><tr><td></td><td></td><td></td><td></td><td>Review new retrieval algorithm developments (DCR and DCR + auxiliary), make recommendations for implementation by the DC</td><td>Updates and new</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
3.4 Operation support for quality assurance and quality control

3.4.1 Definition and establishment of standard operation procedures

The Centre for Cloud Remote Sensing should establish and distribute documents that describe operation procedures that users must follow to get an ACTRIS Cloud remote sensing label (minimum and optimal requirement). These Standard Operation Procedures (SOPs) are defined to ensure the correct deployment and the optimal routine measurements at ACTRIS National Facilities (NFs). The same SOPs should be recommended for operation of Cloud remote sensing instruments external to ACTRIS. The SOPs should cover site requirements, instrument deployment protocols to prevent signal contamination from external sources, instrument operation procedures, maintenance, and calibration requirements.

Millimetre-wave Doppler Cloud Radar

The following SOPs must be established for DCRs with the objective of reaching consistent operation quality within the DCR network. This should include:

* SOP for site requirements (quality of environment, open view of horizon, wave-length, emission frequency regulations);

* SOP for instrument deployment to prevent signal contamination and to have maximum employment of standard procedures vs non-standard procedures (90/10).

* SOP for instrument operation, to adjust the temporal sampling, and define pointing and scanning or ancillary measurement or type of processing and to have continuous operation 24/7.

Milestones:

* First version of SOP to be provided by end of Year 1 of implementation phase (e.g. end of 2020)

Microwave radiometer

The following standard operation procedures must be established for MWR with the objective of reaching consistent operation quality within the MWR network. This should include:

* Site requirements (open view to horizon, preferably in northern direction to perform elevation scans)

* Minimum requirements for observations (temporal resolution of data, noise level of BT observations, stability, available frequencies/channels)

* Firmware requirements

* Calibration and Maintenance requirements (regular inspection, housekeeping data)

* Consistent retrieval algorithms for atmospheric parameters (cloud liquid water path, temperature profiles)

* Data flow implementation (common procedure from instrument to data centre)

The TC should provide guidelines and routines for the NFs and should regularly check the implementation of the guidelines via routine quality checks. The responsibility of implementation is at the level of the NF.

Milestones:

* First version of SOP to be provided by end of Year 1 of implementation phase. These SOP should be further developed in the implementation phase.
3.4 Operation support for quality assurance and quality control

3.4.1 Definition and establishment of standard operation procedures

The Centre for Cloud Remote Sensing should establish and distribute documents that describe operation procedures that users must follow to get an ACTRIS Cloud remote sensing label (minimum and optimal requirement). These Standard Operation Procedures (SOPs) are defined to ensure the correct deployment and the optimal routine measurements at ACTRIS National Facilities (NFs). The same SOPs should be recommended for operation of Cloud remote sensing instruments external to ACTRIS. The SOPs should cover site requirements, instrument deployment protocols to prevent signal contamination from external sources, instrument operation procedures, maintenance, and calibration requirements.

Millimetre-wave Doppler Cloud Radar

The following SOPs must be established for DCRs with the objective of reaching consistent operation quality within the DCR network. This should include:

* SOP for site requirements (quality of environment, open view of horizon, wave-length, emission frequency regulations);

* SOP for instrument deployment to prevent signal contamination and to have maximum employment of standard procedures vs non-standard procedures (90/10).

* SOP for instrument operation, to adjust the temporal sampling, and define pointing and scanning or ancillary measurement or type of processing and to have continuous operation 24/7.

Milestones:

* First version of SOP to be provided by end of Year 1 of implementation phase (e.g. end of 2020)

Microwave radiometer

The following standard operation procedures must be established for MWR with the objective of reaching
consistent operation quality within the MWR network. This should include:

* Site requirements (open view to horizon, preferably in northern direction to perform elevation scans)

* Minimum requirements for observations (temporal resolution of data, noise level of BT observations, stability, available frequencies/channels)

* Firmware requirements

* Calibration and Maintenance requirements (regular inspection, housekeeping data)

* Consistent retrieval algorithms for atmospheric parameters (cloud liquid water path, temperature profiles)

* Data flow implementation (common procedure from instrument to data centre)

The TC should provide guidelines and routines for the NFs and should regularly check the implementation of the guidelines via routine quality checks. The responsibility of implementation is at the level of the NF.

Milestones:

* First version of SOP to be provided by end of Year 1 of implementation phase. These SOP should be further developed in the implementation phase.
## Doppler Wind Lidar

The following SOPs must be established for DWLs with the objective of reaching consistent operation quality within the network. This should include:

* SOP for site requirements to determine scanning capability (open view within a cone of specified elevation angle from zenith necessary to obtain a wind profile, and preferably open view to horizon to enable low-elevation scans)

* SOP for scanning sequence selection to ensure that required parameters are obtained with sufficient regularity

* SOP for instrument operation, including temporal sampling, telescope focus calibration, pointing angle determination

* Calibration and firmware requirements (housekeeping data)

* Data flow implementation (common procedure from instrument to data centre)

### Milestones:

* First version of SOP to be provided by end of Year 1 of implementation phase (e.g. end of 2020)

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

A major objective of the TC is to ensure network-wide accurate calibration of each DCR and MWR installed in ACTRIS NFs following harmonized protocols and tools. Regular calibration of each instrument is necessary to put all measurements on a common absolute scale.

The calibration of each instrument covered by the TC should be based on tested and traceable procedures possibly including multiple techniques: e.g. (1) absolute calibration based on calibrated targets, (2) relative calibration using calibration transfer from a reference instrument, (3) absolute calibration using geophysical targets with known characteristics. The TC should be responsible for the development and delivery of procedures for specific calibration of DCRs and MWRs at each ACTRIS NF. The calibration service could be provided at the TC facility or at NFs, depending on the feasibility. It should offer low-uncertainty reference calibration according to robust calibration techniques. Regular calibration workshops open to NF operators should be organized at the TC.

## Millimetre-wave Doppler Cloud Radar

At least three types of calibration should be proposed for the DCR:

**Cross-check recommendations:** (1) autonomous-user calibration procedure based on natural targets (using recommended ancillary measurements);

**Low-uncertainty reference calibration:** (2) calibration at TC facility based on reference targets; (3) calibration at NF facility using TC reference equipment (calibration kit).

The TC should maintain reference equipment for DCR calibration at the TC facility and also in a mobile setup to implement "low-uncertainty reference calibration". The TC should support NF operators through training of DCR calibration techniques based on natural targets.

The TC should offer low-uncertainty reference calibration to NFs once every 2 years.

* Develop external calibration procedures with specific experimental set-up for each instrument: sensitivity, accuracy, stability;

* Quantify the stability of the mobile reference DCR after several calibration exercises on NFs.
## Doppler Wind Lidar

The following SOPs must be established for DWLs with the objective of reaching consistent operation quality within the network. This should include:

* SOP for site requirements to determine scanning capability (open view within a cone of specified elevation angle from zenith necessary to obtain a wind profile, and preferably open view to horizon to enable low-elevation scans)

* SOP for scanning sequence selection to ensure that required parameters are obtained with sufficient regularity

* SOP for instrument operation, including temporal sampling, telescope focus calibration, pointing angle determination

* Calibration and firmware requirements (housekeeping data)

* Data flow implementation (common procedure from instrument to data centre)

### Milestones:

* First version of SOP to be provided by end of Year 1 of implementation phase (e.g. end of 2020)

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

A major objective of the TC is to ensure network-wide accurate calibration of each DCR and MWR installed in ACTRIS NFs following harmonized protocols and tools. Regular calibration of each instrument is necessary to put all measurements on a common absolute scale.

The calibration of each instrument covered by the TC should be based on tested and traceable procedures possibly including multiple techniques: e.g. (1) absolute calibration based on calibrated targets, (2) relative calibration using calibration transfer from a reference instrument, (3) absolute calibration using geophysical targets with known characteristics. The TC should be responsible for the development and delivery of procedures for specific calibration of DCRs and MWRs at each ACTRIS NF. The calibration service could be provided at the TC facility or at NFs, depending on the feasibility. It should offer low-uncertainty reference calibration according to robust calibration techniques. Regular calibration workshops open to NF operators should be organized at the TC.

## Millimetre-wave Doppler Cloud Radar

At least three types of calibration should be proposed for the DCR:

**Cross-check recommendations:** (1) autonomous-user calibration procedure based on natural targets (using recommended ancillary measurements);

**Low-uncertainty reference calibration:** (2) calibration at TC facility based on reference targets; (3) calibration at NF facility using TC reference equipment (calibration kit).

The TC should maintain reference equipment for DCR calibration at the TC facility and also in a mobile setup to implement "low-uncertainty reference calibration". The TC should support NF operators through training of DCR calibration techniques based on natural targets.

The TC should offer low-uncertainty reference calibration to NFs once every 2 years.

* Develop external calibration procedures with specific experimental set-up for each instrument: sensitivity, accuracy, stability;

* Quantify the stability of the mobile reference DCR after several calibration exercises on NFs.
Milestones:

* Recommendations for all calibration types (natural and metallic target)

* Calibration monitoring software and guidelines

* Calibration intercomparisons of different methods to quantify uncertainties and variability over time.

Technical requirements (minimal and optimal) for DCR as described in the NF document. TC should establish these requirements.

* One reference cloud radar with the best sensitivity in vertical pointing: to calibrate the cloud radar with a reference with the highest performance.

* One cloud radar in scanning mode: to be able to align on the mast or drone metallic target and validate the cloud radar calibration.

* One calibration mast with well-characterized metallic target: to know the reference value of reflectivity we should have

* One drone with well-characterized metallic target: to know the reference value of reflectivity we should have

* One standard meteorological station (pressure, temperature, humidity, wind, precipitation and horizontal visibility): to characterize the environmental set-up.

* One disdrometer: to characterize the drop size distribution necessary for calibration during rain events.

* Equipment for external monitoring of transmitted radar power and attenuation due to radome wetting by rain.

## Microwave radiometer

For MWR, guidelines for calibration procedures should be provided by the TC to the NFs. Regular calibration workshops for NF operators should be performed at the TC (see 3.4.1).

* Absolute calibration using liquid nitrogen (LN2) should be performed every 6 months or when spurious data are detected. Details should be provided by the TC. An extended calibration QC compared to the manufacturer's standard is important, by observing cold-load brightness temperatures before and after the calibration.

* Automatic routine for detector noise levels and cross-correlation

* Relative calibration (hot-load/noise-diode) should be part of the standard operation procedures.

* Automatic documentation of relative calibrations has to be guaranteed (storage of quality flags, data, noise level, etc.), manual documentation of absolute calibration, instrument maintenance (e.g. radome change) and instrument site changes

* Calibration schedule depending on instrument type

Milestones:

* Instrument specific recommendations for all calibration types

* Calibration monitoring software and guidelines

* Calibration intercomparisons of different instrument types and generations should provide more instrument-specific calibration procedures
Milestones:

* Recommendations for all calibration types (natural and metallic target)

* Calibration monitoring software and guidelines

* Calibration intercomparisons of different methods to quantify uncertainties and variability over time.

Technical requirements (minimal and optimal) for DCR as described in the NF document. TC should establish these requirements.

* One reference cloud radar with the best sensitivity in vertical pointing: to calibrate the cloud radar with a reference with the highest performance.

* One cloud radar in scanning mode: to be able to align on the mast or drone metallic target and validate the cloud radar calibration.

* One calibration mast with well-characterized metallic target: to know the reference value of reflectivity we should have

* One drone with well-characterized metallic target: to know the reference value of reflectivity we should have

* One standard meteorological station (pressure, temperature, humidity, wind, precipitation and horizontal visibility): to characterize the environmental set-up.

* One disdrometer: to characterize the drop size distribution necessary for calibration during rain events.

* Equipment for external monitoring of transmitted radar power and attenuation due to radome wetting by rain.

## Microwave radiometer

For MWR, guidelines for calibration procedures should be provided by the TC to the NFs. Regular calibration workshops for NF operators should be performed at the TC (see 3.4.1).

* Absolute calibration using liquid nitrogen (LN2) should be performed every 6 months or when spurious data are detected. Details should be provided by the TC. An extended calibration QC compared to the manufacturer's standard is important, by observing cold-load brightness temperatures before and after the calibration.

* Automatic routine for detector noise levels and cross-correlation

* Relative calibration (hot-load/noise-diode) should be part of the standard operation procedures.

* Automatic documentation of relative calibrations has to be guaranteed (storage of quality flags, data, noise level, etc.), manual documentation of absolute calibration, instrument maintenance (e.g. radome change) and instrument site changes

* Calibration schedule depending on instrument type

Milestones:

* Instrument specific recommendations for all calibration types

* Calibration monitoring software and guidelines

* Calibration intercomparisons of different instrument types and generations should provide more instrument-specific calibration procedures
<figure><img src="image_17.png" /></figure>

## Doppler Wind lidar

Azimuthal pointing angle calibration necessary to ensure reliable wind retrievals can be achieved by scanning across a hard target of known location in the far field, such as a mast, or through consistency checks via intercomparison of retrieved winds with ground-based anemometers or radiosonde profiles. Both methods also ensure that the instrument is providing reliable radial velocities. For DWL, guidelines for calibration procedures should be provided by the TC to the NFs.

* Azimuthal pointing angle calibration should be performed on a routine basis by including a specific scan once per day or once per hour

Milestones:

* Location specific recommendations for calibration

* Calibration monitoring software and guidelines

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

Standard procedures for quality assurance and quality check (QA/QC) should be developed and provided to NFs to ensure that instrument operators have the means to monitor measurement quality, can take corrective actions when measurement quality changes, and control the calibration quality. A list of housekeeping data and QA/QC flags should be developed to identify measurements that are not compliant with requirements for Doppler Cloud Radars, Microwave Radiometers, and Doppler Wind Lidars. Criteria and procedures should be made available at the end of the ACTRIS-PPP.

The TC should provide QA/QC guidelines to the NFs and should regularly check the implementation of the guidelines via routine quality checks (see 3.3.4). The responsibility of implementation is at the level of the NF.

<figure><img src="image_18.png" /></figure>

## Millimetre-wave Doppler Cloud Radar

The following QA/QC procedures are necessary for DCR operation:

* Instrument stability monitoring on transmitter and receiver side

* Detailed instrument monitoring and documentation (housekeeping data)

* Check of hardware components (radome, amplifier, antenna);

* Flagging for data quality (near-range)

* External hardware to measure transmitted power outside the instrument, hence including water on the radome.

* Analysis of log data (housekeeping) provided by the firmware

Milestones:

* Data flagging method and support to analyse the QC.

* Maintenance schedule

<figure><img src="image_19.png" /></figure>

## Microwave radiometer

The following QA/QC procedures are necessary for MWR operation:

* Detailed instrument monitoring and documentation (housekeeping data)

* Calibration quality control (e.g. clear-sky radiosondes)

* Regular check of hardware components, cleaning of radome, radome coating
## Doppler Wind lidar

Azimuthal pointing angle calibration necessary to ensure reliable wind retrievals can be achieved by scanning across a hard target of known location in the far field, such as a mast, or through consistency checks via intercomparison of retrieved winds with ground-based anemometers or radiosonde profiles. Both methods also ensure that the instrument is providing reliable radial velocities. For DWL, guidelines for calibration procedures should be provided by the TC to the NFs.

* Azimuthal pointing angle calibration should be performed on a routine basis by including a specific scan once per day or once per hour

Milestones:

* Location specific recommendations for calibration

* Calibration monitoring software and guidelines

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

Standard procedures for quality assurance and quality check (QA/QC) should be developed and provided to NFs to ensure that instrument operators have the means to monitor measurement quality, can take corrective actions when measurement quality changes, and control the calibration quality. A list of housekeeping data and QA/QC flags should be developed to identify measurements that are not compliant with requirements for Doppler Cloud Radars, Microwave Radiometers, and Doppler Wind Lidars. Criteria and procedures should be made available at the end of the ACTRIS-PPP.

The TC should provide QA/QC guidelines to the NFs and should regularly check the implementation of the guidelines via routine quality checks (see 3.3.4). The responsibility of implementation is at the level of the NF.

## Millimetre-wave Doppler Cloud Radar

The following QA/QC procedures are necessary for DCR operation:

* Instrument stability monitoring on transmitter and receiver side

* Detailed instrument monitoring and documentation (housekeeping data)

* Check of hardware components (radome, amplifier, antenna);

* Flagging for data quality (near-range)

* External hardware to measure transmitted power outside the instrument, hence including water on the radome.

* Analysis of log data (housekeeping) provided by the firmware

Milestones:

* Data flagging method and support to analyse the QC.

* Maintenance schedule

## Microwave radiometer

The following QA/QC procedures are necessary for MWR operation:

* Detailed instrument monitoring and documentation (housekeeping data)

* Calibration quality control (e.g. clear-sky radiosondes)

* Regular check of hardware components, cleaning of radome, radome coating
* Camera inspection

* Flagging for data quality by spectral consistency checks: If one or more channels of the MWR are faulty, this check can detect inconsistencies (caused e.g. by external radio frequency interference, rain, wet radome or failed calibration) by comparing to typical atmospheric spectra.

Milestones:

* Implementation of housekeeping data visualization

* Data flagging procedure, spectral consistency check implementation

* Maintenance schedule

<figure><img src="image_20.png" /></figure>

Doppler Wind Lidar

The following QA/QC procedures are necessary for DWL operation:

* Detailed instrument monitoring and documentation (housekeeping data), especially background monitoring

* Azimuthal pointing angle calibration

* Telescope focus correction

Milestones:

* Implementation of housekeeping data visualization

* Implementation of routine pointing angle calibration

### 3.4.4 Development and provision of in-house check-up tools

Instrument housekeeping data and calibration data should be collected by NFs for each cloud remote sensing instrument. Instruments should produce housekeeping data automatically. Instruments should produce calibration data when operated in calibration mode (specific mode to be defined). Continuous analysis of this data should allow instrument operators to check the quality of their measurements. To perform this analysis, the TC should provide software tools and visualization tools to check the instrument performance and possible calibration trends. This should include In-house check-up tools that operators at NF can execute to analyze the housekeeping parameters automatically stored by the instrument in order to monitor the instrument performance and stability. The TC should develop such in-house check-up tools in an open-source programming language (i.e. Python).

### 3.4.5 Development of data evaluation procedures and plausibility test

Doppler cloud radar and microwave radiometer data should be sent by NFs to the ACTRIS Cloud Remote Sensing Data Centre. The DC should then be responsible for processing data to produce retrievals of relevant Cloud geophysical properties. Data evaluation, based on various tests should then be implemented to qualify the retrieved data. Methods to test retrieved data should be established by the TC (e.g. evaluating plausible range, internal consistency, multi-instrument intercomparisons,...) and data evaluation procedures should be developed by the TC and provided to the DC for implementation. This software should be developed as open-access software.
* Camera inspection

* Flagging for data quality by spectral consistency checks: If one or more channels of the MWR are faulty, this check can detect inconsistencies (caused e.g. by external radio frequency interference, rain, wet radome or failed calibration) by comparing to typical atmospheric spectra.

Milestones:

* Implementation of housekeeping data visualization

* Data flagging procedure, spectral consistency check implementation

* Maintenance schedule

<figure><img src="image_18.png" /></figure>

Doppler Wind Lidar

The following QA/QC procedures are necessary for DWL operation:

* Detailed instrument monitoring and documentation (housekeeping data), especially background monitoring

* Azimuthal pointing angle calibration

* Telescope focus correction

Milestones:

* Implementation of housekeeping data visualization

* Implementation of routine pointing angle calibration

### 3.4.4 Development and provision of in-house check-up tools

Instrument housekeeping data and calibration data should be collected by NFs for each cloud remote sensing instrument. Instruments should produce housekeeping data automatically. Instruments should produce calibration data when operated in calibration mode (specific mode to be defined). Continuous analysis of this data should allow instrument operators to check the quality of their measurements. To perform this analysis, the TC should provide software tools and visualization tools to check the instrument performance and possible calibration trends. This should include In-house check-up tools that operators at NF can execute to analyze the housekeeping parameters automatically stored by the instrument in order to monitor the instrument performance and stability. The TC should develop such in-house check-up tools in an open-source programming language (i.e. Python).

### 3.4.5 Development of data evaluation procedures and plausibility test

Doppler cloud radar and microwave radiometer data should be sent by NFs to the ACTRIS Cloud Remote Sensing Data Centre. The DC should then be responsible for processing data to produce retrievals of relevant Cloud geophysical properties. Data evaluation, based on various tests should then be implemented to qualify the retrieved data. Methods to test retrieved data should be established by the TC (e.g. evaluating plausible range, internal consistency, multi-instrument intercomparisons,...) and data evaluation procedures should be developed by the TC and provided to the DC for implementation. This software should be developed as open-access software.
## Millimetre-wave Doppler Cloud Radar

Data evaluation and plausibility check is a critical issue for DCRs.

* Should come up with plausible range of Reflectivity values based on statistics, and also some constraints based on MWR LWP and Cloud geometrical depth, and possibly Doppler velocity.

* Horizontal wind speed derived with scanning cloud radar can be compared with radiosonde measurement.

Milestones:

* Implementation of reflectivity consistency checks

* Implementation of liquid water closure

* Implementation of data flagging procedure

## Microwave radiometer

Data evaluation and plausibility check is a critical issue for MWR. These checks should be performed directly after measurement at the NF/DC, to detect inconsistencies and other problems.

* Comparison of retrieved atmospheric parameters to other observations (e.g. IWV of GPS)

* Comparison of observed brightness temperatures to products or forward-modelled brightness temperatures of NWP models to detect systematic biases (O-B)

Milestones:

* Implementation of comparison to other observations and/or models

* Implementation of data flagging procedure

## Doppler wind lidar

Data evaluation and plausibility checks are necessary for DWLs.

* Horizontal wind speeds derived from scanning can be compared with ground/mast-based anemometers or radiosonde.

* Turbulent parameters can be compared at the surface with sonic-anemometers

* Comparison of retrieved atmospheric parameters to other observations (e.g. aerosol or low-power lidars)

Milestones:

* Implementation of comparison to other observations and/or models

* Implementation of data flagging procedure

### 3.4.6 Realization of observational site performance audits with reference samples or mobile systems

The TC should realize observational site performance audits. To limit the human resources required for such audits, the audit method should be based on a questionnaire that should be filled by NFs. The questionnaire should include important aspects such as instrument installation, operation, quality control, preventive maintenance, calibration, and data availability. Semi-automatic review procedures should be developed to review log books and metadata about instrument stability monitoring, calibration, measurement quality, data quality control.
## Millimetre-wave Doppler Cloud Radar

Data evaluation and plausibility check is a critical issue for DCRs.

* Should come up with plausible range of Reflectivity values based on statistics, and also some constraints based on MWR LWP and Cloud geometrical depth, and possibly Doppler velocity.

* Horizontal wind speed derived with scanning cloud radar can be compared with radiosonde measurement.

Milestones:

* Implementation of reflectivity consistency checks

* Implementation of liquid water closure

* Implementation of data flagging procedure

## Microwave radiometer

Data evaluation and plausibility check is a critical issue for MWR. These checks should be performed directly after measurement at the NF/DC, to detect inconsistencies and other problems.

* Comparison of retrieved atmospheric parameters to other observations (e.g. IWV of GPS)

* Comparison of observed brightness temperatures to products or forward-modelled brightness temperatures of NWP models to detect systematic biases (O-B)

Milestones:

* Implementation of comparison to other observations and/or models

* Implementation of data flagging procedure

## Doppler wind lidar

Data evaluation and plausibility checks are necessary for DWLs.

* Horizontal wind speeds derived from scanning can be compared with ground/mast-based anemometers or radiosonde.

* Turbulent parameters can be compared at the surface with sonic-anemometers

* Comparison of retrieved atmospheric parameters to other observations (e.g. aerosol or low-power lidars)

Milestones:

* Implementation of comparison to other observations and/or models

* Implementation of data flagging procedure

### 3.4.6 Realization of observational site performance audits with reference samples or mobile systems

The TC should realize observational site performance audits. To limit the human resources required for such audits, the audit method should be based on a questionnaire that should be filled by NFs. The questionnaire should include important aspects such as instrument installation, operation, quality control, preventive maintenance, calibration, and data availability. Semi-automatic review procedures should be developed to review log books and metadata about instrument stability monitoring, calibration, measurement quality, data quality control.
Millimetre-wave Doppler Cloud Radar

A mobile reference DCR should be available and used to evaluate measurements at NF sites that reveal data quality problems that cannot be solved by other methods.

Microwave radiometer

The site audit with reference systems should not be preferred method for MWRs since the calibration of
any system has to be performed after each transport. A mobile MWR unit could only determine the
repeatability of absolute calibrations of a MWR at the NF.

A reference system could consist of a mobile radiosounding system for direct clear-sky comparisons to the MWR system, if no operational radiosonde station is situated close to the MWR location. However, this cannot be done for all MWR in a network on a regular basis.

The standard method should be to have remote access to the instrument/host PC in case of problems
with providing QC data, as site visits cannot be standard procedure.

3.4.7 Organization of regular exercises to assess the performances of the NFs, including instrument performance workshops

Once per year, the TC should organize a workshop that gathers all NF operators to discuss measurement performance, data quality issues, instrument issues. This workshop should allow for new methods to be presented (by the TC and NFs) that aim at improving the overall quality of the cloud remote sensing data. This workshop should be organized at the TC or at NFs, providing opportunities to visit observation sites.

3.4.8 Contribution to documentation and traceability of level 0 to level 3 data products

The TC should contribute to the documentation and the traceability of all the data product levels based on quality assurance, calibration and quality control steps (see section 3.3.2, 3.3.3 and 3.3.5). Discussion should be conducted with the ACTRIS Data Centre to codify this traceability for raw data (level 0), pre-processed data (level 1), fully controlled atmospheric products (level 2), and their climatological aggregations (level 3). This traceability is necessary for all the procedures starting from the instrument deployment to the QA/QC analysis. Homogeneous and complete documentation of the metadata file is essential to develop data flags with the ACTRIS DC.

3.4.9 Contribution to CEN, ISO, or similar standardization activities

The standardization process should not be a significant TC activity even if some work could be done to
normalize processes that can be useful for commercial use. Some recommendations could be made to
manufacturers to have a standard for atmospheric measurement techniques, concerning the Doppler
cloud radar and microwave radiometer.
Millimetre-wave Doppler Cloud Radar

A mobile reference DCR should be available and used to evaluate measurements at NF sites that reveal
data quality problems that cannot be solved by other methods.

Microwave radiometer

The site audit with reference systems should not be preferred method for MWRs since the calibration of
any system has to be performed after each transport. A mobile MWR unit could only determine the
repeatability of absolute calibrations of a MWR at the NF.

A reference system could consist of a mobile radiosounding system for direct clear-sky comparisons to the MWR system, if no operational radiosonde station is situated close to the MWR location. However, this cannot be done for all MWR in a network on a regular basis.

The standard method should be to have remote access to the instrument/host PC in case of problems
with providing QC data, as site visits cannot be standard procedure.

3.4.7 Organization of regular exercises to assess the performances of the NFs, including instrument performance workshops

Once per year, the TC should organize a workshop that gathers all NF operators to discuss measurement performance, data quality issues, instrument issues. This workshop should allow for new methods to be presented (by the TC and NFs) that aim at improving the overall quality of the cloud remote sensing data. This workshop should be organized at the TC or at NFs, providing opportunities to visit observation sites.

3.4.8 Contribution to documentation and traceability of level 0 to level 3 data products

The TC should contribute to the documentation and the traceability of all the data product levels based
on quality assurance, calibration and quality control steps (see section 3.3.2, 3.3.3 and 3.3.5). Discussion
should be conducted with the ACTRIS Data Centre to codify this traceability for raw data (level 0), pre-
processed data (level 1), fully controlled atmospheric products (level 2), and their climatological
aggregations (level 3). This traceability is necessary for all the procedures starting from the instrument
deployment to the QA/QC analysis. Homogeneous and complete documentation of the metadata file is
essential to develop data flags with the ACTRIS DC.

3.4.9 Contribution to CEN, ISO, or similar standardization activities

The standardization process should not be a significant TC activity even if some work could be done to
normalize processes that can be useful for commercial use. Some recommendations could be made to
manufacturers to have a standard for atmospheric measurement techniques, concerning the Doppler
cloud radar and microwave radiometer.
## 3.5 Operation support for knowledge transfer and training

### 3.5.1 Training of operators and scientists

Training of operators and scientists should be organized to fulfil different requirements: calibration procedures or techniques, training of new operators, support to implement standard operation procedures, data quality control procedures. These training events should have a limited number of participants and could be organized at the different TC units depending on the topics. Workshops on instrument calibration should include background and hands-on training, and hence each training session should have a limited number of participants. Scientists at NFs should get more insight into QA/QC procedures and learn how to detect problems and other issues of their instruments. An online forum for exchange between the NF operators and scientists could also cover this topic.

The TC should propose one additional workshop per year for a wider audience that will focus on new or improved procedures concerning measurement and calibration techniques, data processing algorithms. Space should be provided to share operator and scientist experience and needs related to specific activities.

### 3.5.2 Consultancy for setting-up new observational or exploratory platforms and new instruments at the NFs

The TC should propose consultancy on Doppler cloud radars and microwave radiometers to the NFs that would like to have new observational or exploratory platforms, and new instruments. Based on its experience, the TC should provide consultancy during visits, discussions, workshops and support to the manufacturers. The TC should propose support to NFs that plan to install new DCRs and MWRs to ensure that new instruments are deployed following current state-of-the-art procedures. This support should be proposed at the end of the preparatory phase (2019).

For Doppler cloud radars and microwave radiometers, similar consultancy should be proposed with:

* A service for instrument location definition and site selection support;

* A draft of technical requirements and standard operational support;

* A methodology to analyze instrument performance and selection.

## 3.6 Operation support for improvement of measurement methodologies

### 3.6.1 Testing of new measurement instruments and procedures

The TC should provide space and infrastructure to test new instruments. Performance, accuracy, stability and calibration procedures can be assessed by comparing them to established and well-characterized instruments. This service should be proposed to NFs and ACTRIS users. All the techniques, procedures and supports are presented in section 3.3.3. These supports to test new instruments and procedures should be proposed at the end of the preparatory phase (2019).
## 3.5 Operation support for knowledge transfer and training

### 3.5.1 Training of operators and scientists

Training of operators and scientists should be organized to fulfil different requirements: calibration procedures or techniques, training of new operators, support to implement standard operation procedures, data quality control procedures. These training events should have a limited number of participants and could be organized at the different TC units depending on the topics. Workshops on instrument calibration should include background and hands-on training, and hence each training session should have a limited number of participants. Scientists at NFs should get more insight into QA/QC procedures and learn how to detect problems and other issues of their instruments. An online forum for exchange between the NF operators and scientists could also cover this topic.

The TC should propose one additional workshop per year for a wider audience that will focus on new or improved procedures concerning measurement and calibration techniques, data processing algorithms. Space should be provided to share operator and scientist experience and needs related to specific activities.

### 3.5.2 Consultancy for setting-up new observational or exploratory platforms and new instruments at the NFs

The TC should propose consultancy on Doppler cloud radars and microwave radiometers to the NFs that would like to have new observational or exploratory platforms, and new instruments. Based on its experience, the TC should provide consultancy during visits, discussions, workshops and support to the manufacturers. The TC should propose support to NFs that plan to install new DCRs and MWRs to ensure that new instruments are deployed following current state-of-the-art procedures. This support should be proposed at the end of the preparatory phase (2019).

For Doppler cloud radars and microwave radiometers, similar consultancy should be proposed with:

* A service for instrument location definition and site selection support;

* A draft of technical requirements and standard operational support;

* A methodology to analyze instrument performance and selection.

## 3.6 Operation support for improvement of measurement methodologies

### 3.6.1 Testing of new measurement instruments and procedures

The TC should provide space and infrastructure to test new instruments. Performance, accuracy, stability and calibration procedures can be assessed by comparing them to established and well-characterized instruments. This service should be proposed to NFs and ACTRIS users. All the techniques, procedures and supports are presented in section 3.3.3. These supports to test new instruments and procedures should be proposed at the end of the preparatory phase (2019).
3.6.2 Development of strategies to increase the duty cycle of instruments operated at the NFs, to reduce breakdown and maintenance downtime

The TC should develop strategies to increase the duty cycle of instruments operated at the NFs, and to reduce breakdown and maintenance downtime. A forum for NF operators (as already described in 3.4.1) can help identify solutions to upcoming problems. The experience of many NFs should help to provide a clearer view on instrument performance and deficiencies and might also allow the development of improved components together with the manufacturers. A list of components most likely to breakdown or wear out should be compiled and provided to users.

3.6.3 Development of new technological products and methods

New technological products and methods should be developed and proposed for Doppler cloud radars
and microwave radiometers deployed by ACTRIS NFs and external users. Different aspects should be
foreseen such as new experimental set-up, new instruments, and new algorithms. Discussion with
manufacturers and operators on optimizing instrument performance should be conducted.

3.6.4 Development of retrieval algorithms or tools for producing level 1 to 3 data, including the exploitation of instrument synergies

The TC should take an active role in the development and evaluation of retrieval algorithms and tools for producing level 1 to 3 data, including the exploitation of instrument synergies. It should promote community development of open-source retrieval algorithms. The TC should:

* have retrieval algorithm development expertise,

* help coordinate the scientific community involved in retrieval algorithm development,

* assess what algorithms should be implemented by the cloud remote sensing DC,

* propose a retrieval generation framework

For a harmonized and consistent data set across the different NFs, a central development of retrieval algorithms for atmospheric quantities is necessary. This is however a further step after implementing standard operation, quality check, and calibration procedures.
### 3.6.2 Development of strategies to increase the duty cycle of instruments operated at the NFs, to reduce breakdown and maintenance downtime

The TC should develop strategies to increase the duty cycle of instruments operated at the NFs, and to reduce breakdown and maintenance downtime. A forum for NF operators (as already described in 3.4.1) can help identify solutions to upcoming problems. The experience of many NFs should help to provide a clearer view on instrument performance and deficiencies and might also allow the development of improved components together with the manufacturers. A list of components most likely to breakdown or wear out should be compiled and provided to users.

### 3.6.3 Development of new technological products and methods

New technological products and methods should be developed and proposed for Doppler cloud radars and microwave radiometers deployed by ACTRIS NFs and external users. Different aspects should be foreseen such as new experimental set-up, new instruments, and new algorithms. Discussion with manufacturers and operators on optimizing instrument performance should be conducted.

### 3.6.4 Development of retrieval algorithms or tools for producing level 1 to 3 data, including the exploitation of instrument synergies

The TC should take an active role in the development and evaluation of retrieval algorithms and tools for producing level 1 to 3 data, including the exploitation of instrument synergies. It should promote community development of open-source retrieval algorithms. The TC should:

* have retrieval algorithm development expertise,

* help coordinate the scientific community involved in retrieval algorithm development,

* assess what algorithms should be implemented by the cloud remote sensing DC,

* propose a retrieval generation framework

For a harmonized and consistent data set across the different NFs, a central development of retrieval algorithms for atmospheric quantities is necessary. This is however a further step after implementing standard operation, quality check, and calibration procedures.
## 3.7 Provision of the operation support

### 3.7.1 Scheduled support

This TC should provide (1) remote support to NFs, related to procedures and performance evaluation; (2) support based on physical access to ensure network-wide calibration and site evaluations when required; (3) training and opportunities for knowledge sharing. Support requiring physical access and support for training and sharing of knowledge will be proposed as scheduled support advertised on the ACTRIS website and through direct communication with NF operators. Support concerning operation and quality control procedures should be released on a regular basis as updated documents and tools become available.

<table><thead><tr><th>Instrument</th><th>Type of support</th><th>Specific support</th><th>Frequency</th><th>Comments</th></tr></thead><tbody><tr><td rowspan="3">DCR and MWR</td><td>Provision of instrument-specific calibration</td><td>DCR: comparison with reference DCR or using reference targets.</td><td>DCR: Once every 1 or 2 years<br>MWR: Once every 6 months</td><td>And after each major upgrade</td></tr><tr><td>Site performance audits with reference samples or mobile systems*</td><td>Performance audit based on analysis of recorded data.<br>Performance audit based on site visit.</td><td>Once per year based on data.<br>One site visit per NF.</td><td>Additional visit if replacement of instrument.</td></tr><tr><td>Organization of regular exercises to assess the performances of the NFs, including instrument performance workshops*</td><td></td><td>Once per year</td><td></td></tr><tr><td>DCR, MWR, DWL</td><td>Training of operators and scientists*</td><td></td><td>Once per year</td><td>Co-located with instrument performance workshops</td></tr></tbody></table>
## 3.7 Provision of the operation support

### 3.7.1 Scheduled support

This TC should provide (1) remote support to NFs, related to procedures and performance evaluation; (2) support based on physical access to ensure network-wide calibration and site evaluations when required; (3) training and opportunities for knowledge sharing. Support requiring physical access and support for training and sharing of knowledge will be proposed as scheduled support advertised on the ACTRIS website and through direct communication with NF operators. Support concerning operation and quality control procedures should be released on a regular basis as updated documents and tools become available.

<table><thead><tr><th>Instrument</th><th>Type of support</th><th>Specific support</th><th>Frequency</th><th>Comments</th></tr></thead><tbody><tr><td rowspan="3">DCR and MWR</td><td>Provision of instrument-specific calibration</td><td>DCR: comparison with reference DCR or using reference targets.</td><td>DCR: Once every 1 or 2 years<br>MWR: Once every 6 months</td><td>And after each major upgrade</td></tr><tr><td>Site performance audits with reference samples or mobile systems*</td><td>Performance audit based on analysis of recorded data.<br>Performance audit based on site visit.</td><td>Once per year based on data.<br>One site visit per NF.</td><td>Additional visit if replacement of instrument.</td></tr><tr><td>Organization of regular exercises to assess the performances of the NFs, including instrument performance workshops*</td><td></td><td>Once per year</td><td></td></tr><tr><td>DCR, MWR, DWL</td><td>Training of operators and scientists*</td><td></td><td>Once per year</td><td>Co-located with instrument performance workshops</td></tr></tbody></table>
### 3.7.2 Operation support on request

This TC should provide additional support on request for site performance audits in case of major changes at the NF, consultancy for setting up new observation platforms and testing new instruments.

<table><thead><tr><td>Instrument</td><td>Type of support</td><td>Specific support</td><td>Comments</td></tr></thead><tbody><tr><td>DCR and MWR</td><td>Direct comparison with fixed or mobile reference systems</td><td></td><td>Requires physical access support at CCRES or NF</td></tr><tr><td rowspan="3">DCR, MWR, DWL</td><td>Evaluation of new instruments and firmware</td><td></td><td>Based on physical access support or remote support</td></tr><tr><td>Evaluation of new algorithms</td><td></td><td>Based on remote support</td></tr><tr><td>Specific training</td><td></td><td>Requires physical access support at CCRES or NF</td></tr></tbody></table>
3.7.2 Operation support on request

This TC should provide additional support on request for site performance audits in case of major changes at the NF, consultancy for setting up new observation platforms and testing new instruments.

<table><thead><tr><td>Instrument</td><td>Type of support</td><td>Specific support</td><td>Comments</td></tr></thead><tbody><tr><td>DCR and MWR</td><td>Direct comparison with fixed or mobile reference systems</td><td></td><td>Requires physical access support at CCRES or NF</td></tr><tr><td rowspan="3">DCR, MWR, DWL</td><td>Evaluation of new instruments and firmware</td><td></td><td>Based on physical access support or remote support</td></tr><tr><td>Evaluation of new algorithms</td><td></td><td>Based on remote support</td></tr><tr><td>Specific training</td><td></td><td>Requires physical access support at CCRES or NF</td></tr><tr><td></td><td></td><td></td><td></td></tr></tbody></table>
## 4 Services provided to ACTRIS users

An ACTRIS user is a person, a team, or an institution using either ACTRIS data or any other ACTRIS service. ACTRIS users originate from academia, business, industry and public services, from ACTRIS member countries as well as from countries, which are not ACTRIS members, inside and outside Europe.

ACTRIS Cloud remote sensing users are operators of DCRs, MWRs or DWLs from academia (e.g. research institutes and universities operating observational sites), public services such as operational agencies (e.g. meteorological services, air quality agencies,...), businesses (e.g. airports,...), and industry (e.g. instrument manufacturers), that are NOT operating an ACTRIS observational platform (NF).

The CCRES should provide (1) remote service to ACTRIS users, related to procedures and performance evaluation and (2) training and opportunities for knowledge sharing. It is unlikely that the capacity of the CCRES would be sufficient to provide physical access service to ACTRIS users.

A possible business model could be that the CCRES trains instrument manufacturers to provide physical access services to ACTRIS users following procedures established by the CCRES.

Access to some ACTRIS services is open and free, most importantly the access to ACTRIS data, data products, and digital tools provided by the DC, which is the point of entry for free ACTRIS data services. Other access to ACTRIS services is considered competitive access based on capacity or excellence and will require a review process that is centrally managed by the HO/SAMU. SAMU is the single point of entry for user access to all TC services and to some specific services and data products provided by the DC. Access is regulated by both the ACTRIS access policy and the ACTRIS data policy, respectively.

### 4.1 Estimation of the need

An estimation of the number of users who could benefit from the services of CCRES is presented below.

<table><thead><tr><th rowspan="3">Type of ACTRIS user</th><th colspan="3">Number of users to which ACTRIS is providing services</th></tr><tr><th rowspan="2">Now</th><th colspan="2">by 2025</th></tr><tr><th>Min.</th><th>Max.</th></tr></thead><tbody><tr><td rowspan="3">Academia: DCR MWR DWL</td><td>2</td><td>5</td><td>10</td></tr><tr><td>2</td><td>5</td><td>10</td></tr><tr><td>2</td><td>5</td><td>10</td></tr><tr><td rowspan="3">Business: DCR MWR DWL</td><td>0</td><td>5</td><td>15</td></tr><tr><td>0</td><td>5</td><td>15</td></tr><tr><td>0</td><td>5</td><td>15</td></tr><tr><td rowspan="3">Industry: DCR MWR DWL</td><td>3</td><td>3</td><td>5</td></tr><tr><td>3</td><td>3</td><td>5</td></tr><tr><td>3</td><td>3</td><td>5</td></tr><tr><td rowspan="3">Public services: DCR MWR DWL</td><td>2</td><td>5</td><td>10</td></tr><tr><td>2</td><td>5</td><td>10</td></tr><tr><td>2</td><td>5</td><td>10</td></tr></tbody></table>
## 4 Services provided to ACTRIS users

An ACTRIS user is a person, a team, or an institution using either ACTRIS data or any other ACTRIS service. ACTRIS users originate from academia, business, industry and public services, from ACTRIS member countries as well as from countries, which are not ACTRIS members, inside and outside Europe.

ACTRIS Cloud remote sensing users are operators of DCRs, MWRs or DWLs from academia (e.g. research institutes and universities operating observational sites), public services such as operational agencies (e.g. meteorological services, air quality agencies,...), businesses (e.g. airports,...), and industry (e.g. instrument manufacturers), that are NOT operating an ACTRIS observational platform (NF).

The CCRES should provide (1) remote service to ACTRIS users, related to procedures and performance evaluation and (2) training and opportunities for knowledge sharing. It is unlikely that the capacity of the CCRES would be sufficient to provide physical access service to ACTRIS users.

A possible business model could be that the CCRES trains instrument manufacturers to provide physical access services to ACTRIS users following procedures established by the CCRES.

Access to some ACTRIS services is open and free, most importantly the access to ACTRIS data, data products, and digital tools provided by the DC, which is the point of entry for free ACTRIS data services. Other access to ACTRIS services is considered competitive access based on capacity or excellence and will require a review process that is centrally managed by the HO/SAMU. SAMU is the single point of entry for user access to all TC services and to some specific services and data products provided by the DC. Access is regulated by both the ACTRIS access policy and the ACTRIS data policy, respectively.

### 4.1 Estimation of the need

An estimation of the number of users who could benefit from the services of CCRES is presented below.

<table><thead><tr><th rowspan="3">Type of ACTRIS user</th><th colspan="3">Number of users to which ACTRIS is providing services</th></tr><tr><th rowspan="2">Now</th><th colspan="2">by 2025</th></tr><tr><th>Min.</th><th>Max.</th></tr></thead><tbody><tr><td rowspan="3">Academia: DCR MWR DWL</td><td>2</td><td>5</td><td>10</td></tr><tr><td>2</td><td>5</td><td>10</td></tr><tr><td>2</td><td>5</td><td>10</td></tr><tr><td rowspan="3">Business: DCR MWR DWL</td><td>0</td><td>5</td><td>15</td></tr><tr><td>0</td><td>5</td><td>15</td></tr><tr><td>0</td><td>5</td><td>15</td></tr><tr><td rowspan="3">Industry: DCR MWR DWL</td><td>3</td><td>3</td><td>5</td></tr><tr><td>3</td><td>3</td><td>5</td></tr><tr><td>3</td><td>3</td><td>5</td></tr><tr><td rowspan="3">Public services: DCR MWR DWL</td><td>2</td><td>5</td><td>10</td></tr><tr><td>2</td><td>5</td><td>10</td></tr><tr><td>2</td><td>5</td><td>10</td></tr></tbody></table>
## 4.2 Provision of measurement quality assurance and quality control procedures and tools

The CCRES should provide procedures and tools (open source software) for QA/QC of MWR and DCR data to ACTRIS users. The procedures and tools should be the same as the ones developed for ACTRIS NFs. Recommendations for deployment specifications, calibration techniques and algorithm assumption. However, no regular quality assessment by the TC can be guaranteed.

## 4.3 Instrument-specific calibration

Some methods, techniques and instruments should be offered by the CCRES to the ACTRIS users. One training event should be provided to the ACTRIS users to show and explain how a calibration can be performed at their sites depending on which system should be calibrated (scanning radar and zenith-fixed radar for example). A first set of these requirements should be available at the end of the implementation phase (2019)

Established calibration procedures and standards should be provided to users. No regular quality assessment by the TC can be guaranteed.

## 4.4 Knowledge transfer and operator training

The TC should focus its support to the NFs but some support should be offer on request to ACTRIS users. Priority should be given to NF operators and ACTRIS users could also benefit from the following support:

* DCR and MWR calibration training at the TC but also at sites;

* DCR and MWR standard operation procedures;

* Retrieval algorithm workshop to derive cloud microphysical properties;

* Consultancy for new observational and exploratory platform or instruments;

## 4.5 Improvement of measurement and retrieval methodologies for aerosols, clouds, and reactive trace gases

One goal of the TC is to improve the measurement and retrieval methodologies for clouds. To reach this objective, direct and intensive discussions with the DCR and MWR manufacturers should be established. Some parts of training events, workshops and meetings can be dedicated to these fruitful discussions, in order to improve and develop new techniques and methods to optimize measurement, calibration and hence the associated retrievals.
## 4.2 Provision of measurement quality assurance and quality control procedures and tools

The CCRES should provide procedures and tools (open source software) for QA/QC of MWR and DCR data to ACTRIS users. The procedures and tools should be the same as the ones developed for ACTRIS NFs. Recommendations for deployment specifications, calibration techniques and algorithm assumption. However, no regular quality assessment by the TC can be guaranteed.

## 4.3 Instrument-specific calibration

Some methods, techniques and instruments should be offered by the CCRES to the ACTRIS users. One training event should be provided to the ACTRIS users to show and explain how a calibration can be performed at their sites depending on which system should be calibrated (scanning radar and zenith-fixed radar for example). A first set of these requirements should be available at the end of the implementation phase (2019)

Established calibration procedures and standards should be provided to users. No regular quality assessment by the TC can be guaranteed.

## 4.4 Knowledge transfer and operator training

The TC should focus its support to the NFs but some support should be offer on request to ACTRIS users. Priority should be given to NF operators and ACTRIS users could also benefit from the following support:

* DCR and MWR calibration training at the TC but also at sites;

* DCR and MWR standard operation procedures;

* Retrieval algorithm workshop to derive cloud microphysical properties;

* Consultancy for new observational and exploratory platform or instruments;

## 4.5 Improvement of measurement and retrieval methodologies for aerosols, clouds, and reactive trace gases

One goal of the TC is to improve the measurement and retrieval methodologies for clouds. To reach this objective, direct and intensive discussions with the DCR and MWR manufacturers should be established. Some parts of training events, workshops and meetings can be dedicated to these fruitful discussions, in order to improve and develop new techniques and methods to optimize measurement, calibration and hence the associated retrievals.
# 5 Governance and management structure of the Centre for Cloud Remote Sensing

The Units of the Centre for the Cloud Remote Sensing shall be organized according to the specific role of the CF, assuring that the CF complies with the requirements and obligations described in sections 6 and 7 of this document, and considering the general principles described in the *Baseline document for the concept of the Central Facilities*. The Centre for Cloud Remote Sensing shall be organized such that:

* It has a well-defined structure of Units,

* It has a well-defined decision-making process,

* It is coordinated by a CF Director and managed by a CF Management Board, which consists of the CF Director and the CF Unit Heads,

* It has clear and cost-efficient task sharing between the Units,

* It has a risk management strategy,

* It participates in the ACTRIS decision making by sending representative(s) to the ACTRIS legal entity bodies, e.g. to the RI committee.

# 6 Requirements for the Centre for Cloud Remote Sensing

## 6.1 General requirements

In order to be labelled as Centre for Cloud Remote Sensing, the candidate shall:

* Commit for long-term operation, at least 10 years starting with the next year after the implementation as a CF,

* Set-up an appropriate structure of Units, to ensure an adequate functionality of the CF, cost-effective operation, and scalability with respect to the user demands and advancement of the state-of-the art technology,

* Demonstrate the capacity (in terms of material and personnel resources), to ensure the provision of the needed services and operation support, as described in section 6.2

* Provide a feasible implementation and operation plan for the first five years, starting with the next year after the selection as CF,

* Commit to provide a minimum amount of user services, as described in section 4

* Commit to provide the mandatory operation support to the ACTRIS NFs, as described in section 3.

## 6.2 Technical requirements

### 6.2.1 Facilities

The TC should have capacity to host and organize workshops for groups ranging 10-50 participants. The TC should include one or more facilities that have the capacity to host users and their equipment for field tests.
# 5 Governance and management structure of the Centre for Cloud Remote Sensing

The Units of the Centre for the Cloud Remote Sensing shall be organized according to the specific role of the CF, assuring that the CF complies with the requirements and obligations described in sections 6 and 7 of this document, and considering the general principles described in the *Baseline document for the concept of the Central Facilities*. The Centre for Cloud Remote Sensing shall be organized such that:

* It has a well-defined structure of Units,

* It has a well-defined decision-making process,

* It is coordinated by a CF Director and managed by a CF Management Board, which consists of the CF Director and the CF Unit Heads,

* It has clear and cost-efficient task sharing between the Units,

* It has a risk management strategy,

* It participates in the ACTRIS decision making by sending representative(s) to the ACTRIS legal entity bodies, e.g. to the RI committee.

# 6 Requirements for the Centre for Cloud Remote Sensing

## 6.1 General requirements

In order to be labelled as Centre for Cloud Remote Sensing, the candidate shall:

* Commit for long-term operation, at least 10 years starting with the next year after the implementation as a CF,

* Set-up an appropriate structure of Units, to ensure an adequate functionality of the CF, cost-effective operation, and scalability with respect to the user demands and advancement of the state-of-the art technology,

* Demonstrate the capacity (in terms of material and personnel resources), to ensure the provision of the needed services and operation support, as described in section 6.2

* Provide a feasible implementation and operation plan for the first five years, starting with the next year after the selection as CF,

* Commit to provide a minimum amount of user services, as described in section 4

* Commit to provide the mandatory operation support to the ACTRIS NFs, as described in section 3.

## 6.2 Technical requirements

### 6.2.1 Facilities

The TC should have capacity to host and organize workshops for groups ranging 10-50 participants. The TC should include one or more facilities that have the capacity to host users and their equipment for field tests.
<figure><img src="image_21.png" /></figure>

Millimetre-wave Doppler Cloud Radar

For DCR calibration, the TC should include and have the capacity to operate the following equipment:

* One or more cloud radars with scanning capability that will be maintained at a TC facility and serve as reference cloud radar.

* One calibration mast and well-characterized metallic targets that will serve as reference to calibrate cloud radars with scanning capability.

* One drone able to carry a reference target that will serve as reference to calibrate cloud radars without scanning capability

* A set of well-characterized metal targets to be used for absolute calibration

* One or more standard meteorological stations (pressure, temperature, humidity, wind, precipitation and horizontal visibility): to characterize the environmental set-up.

* One or more disdrometers: to characterize the drop size distribution necessary for calibration during rain events.

* A mobile well-characterized Doppler cloud radar with scanning capability that will serve as reference instrument for calibration transfer to DCRs at NFs.

<figure><img src="image_22.png" /></figure>

Microwave Radiometer

For MWR calibration, the TC should include and have the capacity to operate the following equipment:

* One or more MWR with scanning capability that will be maintained at a TC facility and serve as reference instrument.

* Sufficient standard calibration equipment for operator workshops (supply liquid nitrogen, latest version of cold calibration targets)

* One or more standard meteorological station (pressure, temperature, humidity, wind, precipitation and horizontal visibility): to characterize the environmental set-up.

* A state-of-the-art radiosonde station to assess calibration accuracy by independent clear sky radiosonde comparison

6.2.2 Human resources

The TC staff should include expert scientists, qualified operators and technicians with several years of experience in operating DCRs, MWRs and DWLs. Ideally the staff should have experience in instrument development, instrument calibration, data processing, development of retrieval algorithms. The TC staff should also include management and administrative staff to support the organization of the TC and logistical aspects (hosting, transport,...). Experience in provision of support and service to a wide range of users is also important.

The TC should operate with about 10 full-time equivalent positions distributed in 3-4 units.
<figure><img src="image_19.png" /></figure>

Millimetre-wave Doppler Cloud Radar

For DCR calibration, the TC should include and have the capacity to operate the following equipment:

* One or more cloud radars with scanning capability that will be maintained at a TC facility and serve as reference cloud radar.

* One calibration mast and well-characterized metallic targets that will serve as reference to calibrate cloud radars with scanning capability.

* One drone able to carry a reference target that will serve as reference to calibrate cloud radars without scanning capability

* A set of well-characterized metal targets to be used for absolute calibration

* One or more standard meteorological stations (pressure, temperature, humidity, wind, precipitation and horizontal visibility): to characterize the environmental set-up.

* One or more disdrometers: to characterize the drop size distribution necessary for calibration during rain events.

* A mobile well-characterized Doppler cloud radar with scanning capability that will serve as reference instrument for calibration transfer to DCRs at NFs.

<figure><img src="image_20.png" /></figure>

Microwave Radiometer

For MWR calibration, the TC should include and have the capacity to operate the following equipment:

* One or more MWR with scanning capability that will be maintained at a TC facility and serve as reference instrument.

* Sufficient standard calibration equipment for operator workshops (supply liquid nitrogen, latest version of cold calibration targets)

* One or more standard meteorological station (pressure, temperature, humidity, wind, precipitation and horizontal visibility): to characterize the environmental set-up.

* A state-of-the-art radiosonde station to assess calibration accuracy by independent clear sky radiosonde comparison

6.2.2 Human resources

The TC staff should include expert scientists, qualified operators and technicians with several years of experience in operating DCRs, MWRs and DWLs. Ideally the staff should have experience in instrument development, instrument calibration, data processing, development of retrieval algorithms. The TC staff should also include management and administrative staff to support the organization of the TC and logistical aspects (hosting, transport,...). Experience in provision of support and service to a wide range of users is also important.

The TC should operate with about 10 full-time equivalent positions distributed in 3-4 units.
# 7 Selection of the Centre for Cloud Remote Sensing site(s)

The site(s) hosting the Centre for Cloud Remote Sensing are selected based on 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 laboratories, instruments, equipment

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

* The efficiency in providing the 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

* Status of the development of the Units

* No. of existing users

* Adequacy of the decision-making

* Risk management strategy

# 8 Obligations of the Centre for Cloud Remote Sensing

## 8.1 General obligations

The following general obligations shall apply to the Centre for Cloud Remote Sensing while operational:

* 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, availability of time, and material resources,

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

* To implement efficient user interaction activities by:

* Organizing workshops, to interact with users,

* Collecting user feed-back,

* Maintaining the CF and ACTRIS websites,

* To document its activities, 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

### 8.2.1 Technical obligations in relation with the ACTRIS National Facilities

<figure><img src="image_23.png" /></figure>

**Guidelines, quality assurance criteria and procedures**

The Centre for Cloud Remote Sensing is responsible for the quality assurance procedures and guidelines of the ACTRIS measurements conducted at the NFs operating Millimetre-band Doppler Cloud Radars,
# 7 Selection of the Centre for Cloud Remote Sensing site(s)

The site(s) hosting the Centre for Cloud Remote Sensing are selected based on 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 laboratories, instruments, equipment

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

* The efficiency in providing the 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

* Status of the development of the Units

* No. of existing users

* Adequacy of the decision-making

* Risk management strategy

# 8 Obligations of the Centre for Cloud Remote Sensing

## 8.1 General obligations

The following general obligations shall apply to the Centre for Cloud Remote Sensing while operational:

* 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, availability of time, and material resources,

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

* To implement efficient user interaction activities by:

* Organizing workshops, to interact with users,

* Collecting user feed-back,

* Maintaining the CF and ACTRIS websites,

* To document its activities, 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

### 8.2.1 Technical obligations in relation with the ACTRIS National Facilities

<figure><img src="image_21.png" /></figure>

**Guidelines, quality assurance criteria and procedures**

The Centre for Cloud Remote Sensing is responsible for the quality assurance procedures and guidelines of the ACTRIS measurements conducted at the NFs operating Millimetre-band Doppler Cloud Radars,
Microwave Radiometers and Doppler Wind Lidars. For this, the TC should implement the following
operation support for each of the instrument types under its topics:

* Definition and establishment of standard operation procedures (as described in sections 3.3.1)

* Definition of measurement quality-assurance criteria and procedures (as described in sections 3.3.3)

All the procedures, guidelines, quality assurance criteria, plausibility tests, etc. should be documented
and accessible to all related NFs. Specific training sessions with the related NF operators should be
organized to ensure a smooth and correct implementation of the above.

Tools, tests and consultancy for quality control of the measurements

It is duty of the Centre for Cloud Remote Sensing to assist the related NFs in the quality control of their
measurements by providing the following operation support for each of the instrument types under its
topics:

* Development and provision of instrument-specific calibration (as described in sections 3.3.2)

* Development and provision of in-house check-up tools (as described in sections 3.3.4)

* Development of data evaluation procedures and plausibility test (as described in sections 3.3.5)

* Consultancy for setting-up new observational or exploratory platforms and new instruments at the NFs (as described in sections 3.4.2)

* Testing of new measurement instruments and procedures (as described in sections 3.5.1)

This operation support should be offered to the related NFs whenever there is a need, or a significant
progress in the development of these tools, and accompanied by the appropriate training.

Assessment of performances, measurement flagging

The Centre for Cloud Remote Sensing is mandated to assist the Data Centre and the related NFs in the
quality control of the measurements and data, by:

* Realization of observational site performance audits based on semi-automatic review procedures and possibly based on the deployment of mobile reference instruments at NFs (as described in sections 3.3.6)

* Organizing regular exercises to assess the performances of the NFs, including instrument performance workshops (as described in sections 3.3.7)

* Contributing to documentation and traceability of level 0 to level 3 data products (as described in sections 3.3.8)

The activities involving directly the NFs operating Cloud Remote Sensing instruments covered by the TC (e.g. Doppler Cloud Radars and Microwave radiometers) should be scheduled by the TC and provided regularly. The corresponding NFs should participate in these activities according to the plan proposed by the Centre for Cloud Remote Sensing and agreed together with the ACTRIS Scientific Advisory Board (SAB).

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 Centre for Cloud Remote Sensing
should organize training sessions with the NFs operating Cloud Remote Sensing instruments as needed
(see sections 3.4.1).
Microwave Radiometers and Doppler Wind Lidars. For this, the TC should implement the following
operation support for each of the instrument types under its topics:

* Definition and establishment of standard operation procedures (as described in sections 3.3.1)

* Definition of measurement quality-assurance criteria and procedures (as described in sections 3.3.3)

All the procedures, guidelines, quality assurance criteria, plausibility tests, etc. should be documented
and accessible to all related NFs. Specific training sessions with the related NF operators should be
organized to ensure a smooth and correct implementation of the above.

Tools, tests and consultancy for quality control of the measurements

It is duty of the Centre for Cloud Remote Sensing to assist the related NFs in the quality control of their
measurements by providing the following operation support for each of the instrument types under its
topics:

* Development and provision of instrument-specific calibration (as described in sections 3.3.2)

* Development and provision of in-house check-up tools (as described in sections 3.3.4)

* Development of data evaluation procedures and plausibility test (as described in sections 3.3.5)

* Consultancy for setting-up new observational or exploratory platforms and new instruments at the NFs (as described in sections 3.4.2)

* Testing of new measurement instruments and procedures (as described in sections 3.5.1)

This operation support should be offered to the related NFs whenever there is a need, or a significant
progress in the development of these tools, and accompanied by the appropriate training.

Assessment of performances, measurement flagging

The Centre for Cloud Remote Sensing is mandated to assist the Data Centre and the related NFs in the
quality control of the measurements and data, by:

* Realization of observational site performance audits based on semi-automatic review procedures and possibly based on the deployment of mobile reference instruments at NFs (as described in sections 3.3.6)

* Organizing regular exercises to assess the performances of the NFs, including instrument performance workshops (as described in sections 3.3.7)

* Contributing to documentation and traceability of level 0 to level 3 data products (as described in sections 3.3.8)

The activities involving directly the NFs operating Cloud Remote Sensing instruments covered by the TC (e.g. Doppler Cloud Radars and Microwave radiometers) should be scheduled by the TC and provided regularly. The corresponding NFs should participate in these activities according to the plan proposed by the Centre for Cloud Remote Sensing and agreed together with the ACTRIS Scientific Advisory Board (SAB).

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 Centre for Cloud Remote Sensing
should organize training sessions with the NFs operating Cloud Remote Sensing instruments as needed
(see sections 3.4.1).
Improvement of measurement methodologies for cloud remote sensing

Although it is not an obligation, the Centre for Cloud Remote Sensing should work to sustain a high level of performance and to stimulate the advancement of new techniques and methodologies in the cloud remote sensing field by:

* Development of strategies to increase the duty cycle of instruments operated at the NFs, to reduce breakdown and maintenance downtime (as described in section 3.5.2)

* Tests of new technological products and methods (as described in section 3.5.3)

* Development of retrieval algorithms or tools for producing level 1 to 3 data, including the exploitation of instrument synergies (as described in section 3.5.4)

## 8.2.2 Technical obligations in relation with the ACTRIS Data Centre

Regarding ACTRIS data produced by DCRs, MWRs and DWLs, the following general share of responsibilities between the CCRES and the ACTRIS Data Centre applies:

<table><thead><tr><th>Responsibilities of CCRES</th><th>Responsibilities of ACTRIS DC</th></tr></thead><tbody><tr><td><p>The CCRES is responsible for</p><p><strong>developing and facilitating the implementation of</strong></p><ul><li>level-0 data QA/QC tools to be implemented by ACTRIS NFs to keep control on the quality of their measurements</li><li>level-1 to level-3 QA/QC tools to be implemented by ACTRIS DC</li></ul><p>Evaluating the NF performance summaries</p></td><td><p>ACTRIS Data Centre is responsible for</p><ul><li>Implementing QA/QC tests of ACTRIS data (level 1 to level 3 data), which are made available through the ACTRIS data portal</li><li>Producing NF performance summaries based on QA/QC test analyses</li></ul></td></tr><tr><td><p>The CCRES is responsible for</p><ul><li><strong>auditing the ACTRIS NFs</strong> and reviewing their calibration databases</li><li><strong>Deciding on data flag status</strong></li></ul></td><td><p>ACTRIS Data Centre is responsible for</p><ul><li>Maintaining calibration and metadata databases for each ACTRIS NF, based on information provided by NFs</li><li>Providing the <strong>traceability and full documentation of the data quality</strong> of the ACTRIS data</li><li>Maintaining the ACTRIS Cloud remote sensing database</li></ul></td></tr><tr><td><p>The CCRES is responsible for <strong>testing and evaluating new retrieval algorithms or tools</strong> for producing level 1 to 3 data, including the exploitation of instrument synergies</p></td><td><p>ACTRIS Data Centre is responsible for <strong>implementing the approved retrieval algorithms or tools</strong> into the ACTRIS Data Centre operation</p></td></tr></tbody></table>
Improvement of measurement methodologies for cloud remote sensing

Although it is not an obligation, the Centre for Cloud Remote Sensing should work to sustain a high level of performance and to stimulate the advancement of new techniques and methodologies in the cloud remote sensing field by:

* Development of strategies to increase the duty cycle of instruments operated at the NFs, to reduce breakdown and maintenance downtime (as described in section 3.5.2)

* Tests of new technological products and methods (as described in section 3.5.3)

* Development of retrieval algorithms or tools for producing level 1 to 3 data, including the exploitation of instrument synergies (as described in section 3.5.4)

## 8.2.2 Technical obligations in relation with the ACTRIS Data Centre

Regarding ACTRIS data produced by DCRs, MWRs and DWLs, the following general share of responsibilities between the CCRES and the ACTRIS Data Centre applies:

<table><thead><tr><th>Responsibilities of CCRES</th><th>Responsibilities of ACTRIS DC</th></tr></thead><tbody><tr><td><p>The CCRES is responsible for</p><p><strong>developing and facilitating the implementation of</strong></p><ul><li>level-0 data QA/QC tools to be implemented by ACTRIS NFs to keep control on the quality of their measurements</li><li>level-1 to level-3 QA/QC tools to be implemented by ACTRIS DC</li></ul><p>Evaluating the NF performance summaries</p></td><td><p>ACTRIS Data Centre is responsible for</p><ul><li>Implementing QA/QC tests of ACTRIS data (level 1 to level 3 data), which are made available through the ACTRIS data portal</li><li>Producing NF performance summaries based on QA/QC test analyses</li></ul></td></tr><tr><td><p>The CCRES is responsible for</p><ul><li><strong>auditing the ACTRIS NFs</strong> and reviewing their calibration databases</li><li><strong>Deciding on data flag status</strong></li></ul></td><td><p>ACTRIS Data Centre is responsible for</p><ul><li>Maintaining calibration and metadata databases for each ACTRIS NF, based on information provided by NFs</li><li>Providing the <strong>traceability and full documentation of the data quality</strong> of the ACTRIS data</li><li>Maintaining the ACTRIS Cloud remote sensing database</li></ul></td></tr><tr><td><p>The CCRES is responsible for <strong>testing and evaluating new retrieval algorithms or tools</strong> for producing level 1 to 3 data, including the exploitation of instrument synergies</p></td><td><p>ACTRIS Data Centre is responsible for <strong>implementing the approved retrieval algorithms or tools</strong> into the ACTRIS Data Centre operation</p></td></tr></tbody></table>
### 8.2.3 Technical obligations in relation with Centre for Aerosol Remote Sensing

There is a close link to the Centre for Aerosol Remote Sensing (CARS) because low-power lidars and ceilometers (ALCs) are supported by CARS, while they belong to the minimum required instrumentation of NFs for cloud remote sensing. All quality assurance activities concerning cloud products from ALCs are covered by the CCRES, but should be strongly supported by CARS. An intensive communication between CARS and CCRES is mandatory to ensure that all recommended SOPs and methods are compatible for the quality of both aerosol and cloud related products from ALCs.

### 8.2.4 Technical obligations in relation with the ACTRIS users

The CCRES should commit to provide a minimum amount of user services as described in section 4. The provision of services will be made on a case-by-case situation.

## 8.3 Evaluation of the activity of the Centre for Cloud Remote Sensing

Once established and operational, the Centre for Cloud Remote Sensing should be annually evaluated for its performances, against the following KPIs:

<table><thead><tr><th>No.</th><th>Criteria</th><th>Indicators</th><th>Score</th><th>Weight</th></tr></thead><tbody><tr><td rowspan="3">1</td><td rowspan="3">Usefulness for ACTRIS NFs</td><td>No. of operational support units provided to ACTRIS NFs (incl. calibration)</td><td>1 ... 10</td><td rowspan="3">40%</td></tr><tr><td>Level of involvement in developing and disseminating SoPs, QA/QC tests, tools</td><td>1 ... 10</td></tr><tr><td>No of training sessions and workshops open to ACTRIS NFs</td><td>1 ... 10</td></tr><tr><td></td><td></td><td><strong>Average of Usefulness for ACTRIS</strong></td><td></td><td></td></tr><tr><td rowspan="3">2</td><td rowspan="3">Usefulness for ACTRIS users</td><td>Level of involvement in developing and disseminating SoPs, QA/QC tests, tools</td><td></td><td rowspan="3">20%</td></tr><tr><td>No of training sessions and workshops open to ACTRIS users</td><td></td></tr><tr><td></td></tr><tr><td></td><td></td><td><strong>Average of Usefulness for external users</strong></td><td></td><td></td></tr><tr><td rowspan="2">3</td><td rowspan="2">Impact on science & technology</td><td>No. of peer-review papers facilitated</td><td></td><td rowspan="2">30%</td></tr><tr><td>Level of involvement in testing new retrieval algorithms and methods</td><td></td></tr><tr><td></td><td></td><td><strong>Average of S&T Impact</strong></td><td></td><td></td></tr><tr><td rowspan="3">4</td><td rowspan="3">Integration into ACTRI-RI</td><td>Level of collaboration with other nodes and ACTRIS structures (NFs, DC, SAMU, ...)</td><td></td><td rowspan="3">30%</td></tr><tr><td>Quality and readiness of the reports</td><td></td></tr><tr><td></td></tr><tr><td></td><td></td><td><strong>Average of Integration into ACTRI-RI</strong></td><td></td><td></td></tr><tr><td></td><td></td><td><strong>Total score</strong></td><td></td><td></td></tr></tbody></table>
### 8.2.3 Technical obligations in relation with Centre for Aerosol Remote Sensing

There is a close link to the Centre for Aerosol Remote Sensing (CARS) because low-power lidars and ceilometers (ALCs) are supported by CARS, while they belong to the minimum required instrumentation of NFs for cloud remote sensing. All quality assurance activities concerning cloud products from ALCs are covered by the CCRES, but should be strongly supported by CARS. An intensive communication between CARS and CCRES is mandatory to ensure that all recommended SOPs and methods are compatible for the quality of both aerosol and cloud related products from ALCs.

### 8.2.4 Technical obligations in relation with the ACTRIS users

The CCRES should commit to provide a minimum amount of user services as described in section 4. The provision of services will be made on a case-by-case situation.

## 8.3 Evaluation of the activity of the Centre for Cloud Remote Sensing

Once established and operational, the Centre for Cloud Remote Sensing should be annually evaluated for its performances, against the following KPIs:

<table><thead><tr><th>No.</th><th>Criteria</th><th>Indicators</th><th>Score</th><th>Weight</th></tr></thead><tbody><tr><td rowspan="3">1</td><td rowspan="3">Usefulness for ACTRIS NFs</td><td>No. of operational support units provided to ACTRIS NFs (incl. calibration)</td><td>1 ... 10</td><td rowspan="3">40%</td></tr><tr><td>Level of involvement in developing and disseminating SoPs, QA/QC tests, tools</td><td>1 ... 10</td></tr><tr><td>No of training sessions and workshops open to ACTRIS NFs</td><td>1 ... 10</td></tr><tr><td></td><td></td><td><strong>Average of Usefulness for ACTRIS</strong></td><td></td><td></td></tr><tr><td rowspan="3">2</td><td rowspan="3">Usefulness for ACTRIS users</td><td>Level of involvement in developing and disseminating SoPs, QA/QC tests, tools</td><td></td><td rowspan="3">20%</td></tr><tr><td>No of training sessions and workshops open to ACTRIS users</td><td></td></tr><tr><td></td></tr><tr><td></td><td></td><td><strong>Average of Usefulness for external users</strong></td><td></td><td></td></tr><tr><td rowspan="2">3</td><td rowspan="2">Impact on science & technology</td><td>No. of peer-review papers facilitated</td><td></td><td rowspan="2">30%</td></tr><tr><td>Level of involvement in testing new retrieval algorithms and methods</td><td></td></tr><tr><td></td><td></td><td><strong>Average of S&T Impact</strong></td><td></td><td></td></tr><tr><td rowspan="3">4</td><td rowspan="3">Integration into ACTRI-RI</td><td>Level of collaboration with other nodes and ACTRIS structures (NFs, DC, SAMU, ...)</td><td></td><td rowspan="3">30%</td></tr><tr><td>Quality and readiness of the reports</td><td></td></tr><tr><td></td></tr><tr><td></td><td></td><td><strong>Average of Integration into ACTRI-RI</strong></td><td></td><td></td></tr><tr><td></td><td></td><td><strong>Total score</strong></td><td></td><td></td></tr></tbody></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 syntheses 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 hosting the ACTRIS data portal.

**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 the 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 campaign basis and delivering dedicated data to the Data Centre.

**ACTRIS General Assembly (GA)** - a council of ministry- and funding organization representatives of ACTRIS members after 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="1" />](#).

<footnote n="1">¹The 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>
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 syntheses 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 hosting the ACTRIS data portal.

**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 the 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 campaign basis and delivering dedicated data to the Data Centre.

**ACTRIS General Assembly (GA)** - a council of ministry- and funding organization representatives of ACTRIS members after 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="1" />](#).

<footnote n="1">¹The 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>
**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.

**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, in the ideal case SI units.

**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.

**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.
**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.

**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, in the ideal case SI units.

**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.

**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

Baseline document for the Concepts of ACTRIS Central 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

- Baseline document for the Concepts of ACTRIS Central Facilities
Section 7

Concept of the Centre for Reactive Trace Gases in
Situ Measurements
(CGas-SiM)

ACTRIS PPP WP 4 Task 4.1

22.2.2018

Public
Section 7

# Concept of the Centre for Reactive Trace Gases in Situ Measurements
(CGas-SiM)

ACTRIS PPP WP 4 Task 4.1

22.2.2018

Public
Contents

<table><tr><td>1</td><td>Purpose of the document</td><td>4</td></tr><tr><td>2</td><td>Description and role of the Centre for Reactive Trace Gases in Situ Measurements</td><td>4</td></tr><tr><td>2.1</td><td>Framework</td><td>4</td></tr><tr><td>2.2</td><td>Scientific relevance</td><td>5</td></tr><tr><td>2.3</td><td>Mission</td><td>6</td></tr><tr><td>3</td><td>Operation support provided to ACTRIS National Facilities</td><td>8</td></tr><tr><td>3.1</td><td>Measurement techniques covered by the Centre for Reactive Trace Gases in Situ Measurements, and related ACTRIS variables</td><td>8</td></tr><tr><td>3.1.1</td><td>NMHC Gas chromatographic System</td><td>9</td></tr><tr><td>3.1.2</td><td>BVOC Gas chromatographic System</td><td>9</td></tr><tr><td>3.1.3</td><td>Oxy-VOC Measurement Systems</td><td>9</td></tr><tr><td>3.1.4</td><td>Proton-Transfer-Mass-Spectroscopy</td><td>10</td></tr><tr><td>3.1.5</td><td>Direct Aerosol Precursor Measurement Systems</td><td>10</td></tr><tr><td>3.1.6</td><td>Nitrogen Oxides Measurement Systems</td><td>11</td></tr><tr><td>3.2</td><td>Estimation of the need</td><td>11</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>18</td></tr><tr><td>3.4.1</td><td>Definition and establishment of Measurement Guidelines (MG)</td><td>18</td></tr><tr><td>3.4.2</td><td>Definition of measurement quality-assurance criteria and procedures</td><td>19</td></tr><tr><td>3.4.3</td><td>Development and provision of instrument-specific calibration</td><td>19</td></tr><tr><td>3.4.4</td><td>Development and provision of in-house check-up tools</td><td>20</td></tr><tr><td>3.4.5</td><td>Development of data evaluation procedures and plausibility test</td><td>20</td></tr><tr><td>3.4.6</td><td>Realization of observational site performance audits with reference samples or mobile systems</td><td>21</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>22</td></tr><tr><td>3.4.8</td><td>Contribution to documentation and traceability of level 0 to level 3 data products</td><td>22</td></tr><tr><td>3.4.9</td><td>Contribution to CEN, ISO, or similar standardization activities</td><td>23</td></tr><tr><td>3.5</td><td>Operation support for knowledge transfer and training</td><td>23</td></tr><tr><td>3.5.1</td><td>Training of operators and scientists</td><td>23</td></tr><tr><td>3.5.2</td><td>Consultancy for setting-up new observational or exploratory platforms and new instruments at the NFs</td><td>23</td></tr><tr><td>3.6</td><td>Operation support for improvement of measurement methodologies</td><td>23</td></tr><tr><td>3.6.1</td><td>Testing of new measurement instruments and procedures</td><td>23</td></tr></table>
Contents

<table><tr><td>1</td><td>Purpose of the document</td><td>4</td></tr><tr><td>2</td><td>Description and role of the Centre for Reactive Trace Gases in Situ Measurements</td><td>4</td></tr><tr><td>2.1</td><td>Framework</td><td>4</td></tr><tr><td>2.2</td><td>Scientific relevance</td><td>5</td></tr><tr><td>2.3</td><td>Mission</td><td>6</td></tr><tr><td>3</td><td>Operation support provided to ACTRIS National Facilities</td><td>8</td></tr><tr><td>3.1</td><td>Measurement techniques covered by the Centre for Reactive Trace Gases in Situ Measurements, and related ACTRIS variables</td><td>8</td></tr><tr><td>3.1.1</td><td>NMHC Gas chromatographic System</td><td>9</td></tr><tr><td>3.1.2</td><td>BVOC Gas chromatographic System</td><td>9</td></tr><tr><td>3.1.3</td><td>Oxy-VOC Measurement Systems</td><td>9</td></tr><tr><td>3.1.4</td><td>Proton-Transfer-Mass-Spectroscopy</td><td>10</td></tr><tr><td>3.1.5</td><td>Direct Aerosol Precursor Measurement Systems</td><td>10</td></tr><tr><td>3.1.6</td><td>Nitrogen Oxides Measurement Systems</td><td>11</td></tr><tr><td>3.2</td><td>Estimation of the need</td><td>11</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>18</td></tr><tr><td>3.4.1</td><td>Definition and establishment of Measurement Guidelines (MG)</td><td>18</td></tr><tr><td>3.4.2</td><td>Definition of measurement quality-assurance criteria and procedures</td><td>19</td></tr><tr><td>3.4.3</td><td>Development and provision of instrument-specific calibration</td><td>19</td></tr><tr><td>3.4.4</td><td>Development and provision of in-house check-up tools</td><td>20</td></tr><tr><td>3.4.5</td><td>Development of data evaluation procedures and plausibility test</td><td>20</td></tr><tr><td>3.4.6</td><td>Realization of observational site performance audits with reference samples or mobile systems</td><td>21</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>22</td></tr><tr><td>3.4.8</td><td>Contribution to documentation and traceability of level 0 to level 3 data products</td><td>22</td></tr><tr><td>3.4.9</td><td>Contribution to CEN, ISO, or similar standardization activities</td><td>23</td></tr><tr><td>3.5</td><td>Operation support for knowledge transfer and training</td><td>23</td></tr><tr><td>3.5.1</td><td>Training of operators and scientists</td><td>23</td></tr><tr><td>3.5.2</td><td>Consultancy for setting-up new observational or exploratory platforms and new instruments at the NFs</td><td>23</td></tr><tr><td>3.6</td><td>Operation support for improvement of measurement methodologies</td><td>23</td></tr><tr><td>3.6.1</td><td>Testing of new measurement instruments and procedures</td><td>23</td></tr></table>
<table><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>24</td></tr><tr><td>3.6.3</td><td>Development of new technological products and methods</td><td>24</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>24</td></tr><tr><td>4</td><td>Services provided to ACTRIS users</td><td>25</td></tr><tr><td>4.1</td><td>Estimation of the need</td><td>25</td></tr><tr><td>4.2</td><td>Provision of measurement quality assurance and quality control procedures and tools</td><td>26</td></tr><tr><td>4.3</td><td>Instrument-specific calibration</td><td>26</td></tr><tr><td>4.4</td><td>Knowledge transfer and operator training</td><td>26</td></tr><tr><td>4.5</td><td>Improvement of measurement and retrieval methodologies for aerosols, clouds, and reactive trace gases</td><td>26</td></tr><tr><td>5</td><td>Governance and management structure of the Centre for Reactive Trace Gases in Situ Measurements</td><td>27</td></tr><tr><td>6</td><td>Requirements for the Centre for Reactive Trace gases in Situ Measurements</td><td>27</td></tr><tr><td>6.1</td><td>General requirements</td><td>27</td></tr><tr><td>6.2</td><td>Technical requirements</td><td>28</td></tr><tr><td>6.2.1</td><td>Facilities</td><td>28</td></tr><tr><td>6.2.2</td><td>Human resources</td><td>28</td></tr><tr><td>6.2.3</td><td>Other requirements</td><td>29</td></tr><tr><td>7</td><td>Basic criteria for the selection of the Centre for Reactive Trace gases in Situ Measurements</td><td>29</td></tr><tr><td>8</td><td>Obligations of the Centre for Reactive Trace gases in Situ Measurements</td><td>30</td></tr><tr><td>8.1</td><td>General obligations</td><td>30</td></tr><tr><td>8.2</td><td>Technical obligations</td><td>30</td></tr><tr><td>8.2.1</td><td>Technical obligations in relation with the ACTRIS National Facilities</td><td>30</td></tr><tr><td>8.2.2</td><td>Technical obligations in relation with the ACTRIS Data Centre</td><td>32</td></tr><tr><td>8.2.3</td><td>Technical obligations in relation with other TC</td><td>32</td></tr><tr><td>8.2.4</td><td>Technical obligations in relation with the ACTRIS users</td><td>32</td></tr><tr><td>8.3</td><td>Evaluation of the activity of Centre for Reactive Trace gases in Situ Measurements</td><td>32</td></tr><tr><td>9</td><td>Glossary</td><td>35</td></tr><tr><td>10</td><td>Reference documents</td><td>38</td></tr><tr><td colspan="2">Annex: Provision of the operation support</td><td>39</td></tr><tr><td colspan="2">Scheduled support</td><td>39</td></tr><tr><td colspan="2">Operation support on request</td><td>41</td></tr></table>
<table><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>24</td></tr><tr><td>3.6.3</td><td>Development of new technological products and methods</td><td>24</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>24</td></tr><tr><td>4</td><td>Services provided to ACTRIS users</td><td>25</td></tr><tr><td>4.1</td><td>Estimation of the need</td><td>25</td></tr><tr><td>4.2</td><td>Provision of measurement quality assurance and quality control procedures and tools</td><td>26</td></tr><tr><td>4.3</td><td>Instrument-specific calibration</td><td>26</td></tr><tr><td>4.4</td><td>Knowledge transfer and operator training</td><td>26</td></tr><tr><td>4.5</td><td>Improvement of measurement and retrieval methodologies for aerosols, clouds, and reactive trace gases</td><td>26</td></tr><tr><td>5</td><td>Governance and management structure of the Centre for Reactive Trace Gases in Situ Measurements</td><td>27</td></tr><tr><td>6</td><td>Requirements for the Centre for Reactive Trace gases in Situ Measurements</td><td>27</td></tr><tr><td>6.1</td><td>General requirements</td><td>27</td></tr><tr><td>6.2</td><td>Technical requirements</td><td>28</td></tr><tr><td>6.2.1</td><td>Facilities</td><td>28</td></tr><tr><td>6.2.2</td><td>Human resources</td><td>28</td></tr><tr><td>6.2.3</td><td>Other requirements</td><td>29</td></tr><tr><td>7</td><td>Basic criteria for the selection of the Centre for Reactive Trace gases in Situ Measurements</td><td>29</td></tr><tr><td>8</td><td>Obligations of the Centre for Reactive Trace gases in Situ Measurements</td><td>30</td></tr><tr><td>8.1</td><td>General obligations</td><td>30</td></tr><tr><td>8.2</td><td>Technical obligations</td><td>30</td></tr><tr><td>8.2.1</td><td>Technical obligations in relation with the ACTRIS National Facilities</td><td>30</td></tr><tr><td>8.2.2</td><td>Technical obligations in relation with the ACTRIS Data Centre</td><td>32</td></tr><tr><td>8.2.3</td><td>Technical obligations in relation with other TC</td><td>32</td></tr><tr><td>8.2.4</td><td>Technical obligations in relation with the ACTRIS users</td><td>32</td></tr><tr><td>8.3</td><td>Evaluation of the activity of Centre for Reactive Trace gases in Situ Measurements</td><td>32</td></tr><tr><td>9</td><td>Glossary</td><td>35</td></tr><tr><td>10</td><td>Reference documents</td><td>38</td></tr><tr><td>Annex:</td><td>Provision of the operation support</td><td>39</td></tr><tr><td></td><td>Scheduled support</td><td>39</td></tr><tr><td></td><td>Operation support on request</td><td>41</td></tr></table>