#  Introduction to ACTRIS Data Centre

ACTRIS-2 (Aerosols, Clouds, and Trace gases Research InfraStructure)
Integrating Activity (IA) addresses the scope of integrating state-of-the-art
European ground-based stations for long-term observations of aerosols, clouds
and short lived gases. ACTRIS-2 is a unique research infrastructure improving
the quality of atmospheric observations, developing new methods and protocols,
and harmonizing existing observations of the atmospheric variables listed in
Appendix I.

The overall goal of the ACTRIS Data Centre is to provide scientists and other
user groups with free and open access to all ACTRIS infrastructure data,
complemented with access to innovative and mature data products, together with
tools for quality assurance (QA), data analysis and research.

The numerous measurement methodologies applied in ACTRIS result in a
considerable diversity of the data collected. In accordance with these
requirements, the ACTRIS Data Centre consists of three topical data
repositories archiving the measurement data, which are all linked through the
ACTRIS data portal to provide a single access point to all data. Hence, the
ACTRIS Data Centre is founded on 3 topical data repositories:

  * In situ aerosol and trace gas data are reported to EBAS  : _http://ebas.nilu.no/_ • Aerosol remote sensing data are reported to the EARLINET Data base: 

  

_http://access.earlinet.org/EARLINET/_

  * Cloud remote sensing data are reported to the Cloudnet data base  : _http://cloudnet.fmi.fi/_

  

In addition, AERIS contributes with the production and provision of satellite
data that complements the ACTRIS ground-based data  : _http://www.icare.univ-
lille1.fr/catalogue_ .

Generally, the ACTRIS Data Centre and data management activity aim to work in
accordance with the ENVRI Reference Model, hosted a  t _www.envri.eu/rm_ .

#  ACTRIS data set descriptions and ACTRIS data levels

ACTRIS data sets are atmospheric variables listed in Appendix I, measured with
the corresponding recommended methodology. **ACTRIS data -** comprises ACTRIS
variables resulting from measurements that fully comply with the standard
operating procedures (SOP), measurement recommendations, and quality
guidelines established within ACTRIS. Furthermore, the data are qualified as
ACTRIS data sets only if they comply with the additional requirements
specified in section 2.1 -2.3 **.** There is 3 levels of ACTRIS data: o
**ACTRIS level 0 data:** Raw sensor output, either mV or physical units.
Native resolution, metadata necessary for next level.

  * **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. 

  

  * **ACTRIS synthesis product:** Data product from e.g. research activities **,** not under direct ACTRIS responsibility, but ACTRIS offer repository and access. 

  

The list of variables are expected to increase during the progress of ACTRIS,
particularly level 3data products. During ACTRIS-2, e.g. the aerosol and cloud
databases will be augmented with new classification products developed through
the combination of existing sensors with additional instrumentation; and
products providing information about aerosol layering and typing, together
with advanced products derived from long term series or special case analyses.
In addition, new parameters utilising these products will also be prepared,
and standardized pre processed lidar data and NRT optical property profiles
will be available.

##  Aerosol and trace gas in situ data sets

Aerosol and trace gas in situ data are qualified as ACTRIS data only if

  * The atmospheric variables are included in the list in Appendix I 

  

  * The applied procedures comply with the standard operating procedures (SOP), and measurement recommendations and guidelines provided by the ACTRIS in situ community, available from here  _http://actris.nilu.no/Content/SOP_ See section 4.1 of this document for more details. 

  

  * The measurement data are submitted to the topic data base EBAS by using the reporting templates and procedures recommended by the ACTRIS in situ community, and available at  _http://ebas-submit.nilu.no_

  

Datasets fulfilling the requirements above qualify for the “ACTRIS” in situ
data set label. The types of variables are expected to expand during ACTRIS-2.
The data can in addition be associated with other programs and frameworks such
as GAW, EMEP, and national EPA etc. The data originator determines other
project associations.

Standard collection and reporting procedure for aerosol and trace gas in situ
measurement data:

  * Deadline for reporting data is 31 May of the following year from the reported measurements 

  

  * Data are submitted using EBAS EBAS-submit-tool (  _http://ebas-submit.nilu.no/Submit-Data/DataReporting/tools_ )  . This is web based tool to check file formats and metadata. 

  

  * An auto-generated e-mail is sent to the data submitter to confirm that the data is received 

  

  * After submission, the data undergo an automatic format, NASA-Ames 1001, and metadata check, followed by manual inspection. 

  

  * If the data file is accepted, data are imported to EBAS, and feedback is given to the data originator. If there are suspicious data (e.g. suspicious data points/outliers) or format errors (in e.g. metadata, formats, etc.) the data originator is contacted and asked to assess, correct, and re-submit data. 

  

  * Data originators are asked about their project affiliation with collaborating networks and frameworks (EMEP, GAW-WDCA etc.) 

  

  * Trace gas data is made available to GAW-WDCRG; aerosol data are made available to GAWWDCA. 

  

  * Near-real-time (NRT) data collection is set up and the raw data are auto-processed to hourly averages 

  

##  Aerosol remote sensing data sets

Aerosol profile data are qualified as ACTRIS data only if

  * The atmospheric profile variables are included in the list in Appendix I. 

  

  * The applied procedures comply with the recommendations and procedures provided by the ACTRIS profile community available from here  _http://actris.nilu.no/Content/SOP_ ,  harmonised with EARLINET. See section 4.2 of this document for more details. 

  

  * The data are reported to the EARLINET DB in accordance with the reporting procedures (available at  _http://www.earlinet.org_ /  ). 

  

Standard collection and reporting procedure for aerosol profile data:

  * Data originators have the possibility to use, in addition to their own quality-assured method, the common standardized automatic analysis software developed within EARLINET, namely the Single Calculus Chain (SCC), for analysing their own lidar data to obtain optical properties from raw data, and passing through pre processed data. 

  

  * New data shall be uploaded to the EARLINET DB within 3 months after measurement by data originator as preliminary data. These data are automatically available to all internal ACTRIS/EARLINET users. 

  

  * Automatic quality control procedures are applied to data during the submission from the data originator to the ACTRIS/EARLINET database. Only data compliant to the QC are uploaded on the database, while a message reporting the incurred problems is provided to the data originator. 

  

  * Every 3 months further quality control procedures are run on the data. Data compliant also to these QCs are included in a list of files with the highest QC score (QC 2.0), while the ones not passing these QCs are QC 1.0 files. 

  

  * Data are publicly available when the data originator set up this for the files, typically within 1 year from the data submission, however not before all the QC procedures are run on the files. 

  

All documentations related to the QC procedures applied at the moment on the
ACTRIS remotes sensing profiles and to the history of these procedures are
available at  _https://www.earlinet.org/index.php?id=125_ .

The list of files compliant to the different levels of QC are reported at
https://www.earlinet.org/index.php?id=125.

At the beginning of ACTRIS-2 project, the aerosol vertical profile database
contained aerosol optical properties profiles. By the end of the ACTRIS-2
project, it will be augmented with more products, providing also information
about the layering, and typing. In addition, standardized pre-processed lidar
data and NRT optical properties profiles will be available. In the process to
reach this goal, some of the products are already available even if not
directly on the topical data centre: under Data Originator consensus Level 1
data are made available to the AERIS/ICARE service for combined data product
retrieval andLev1 and lev 1.5 to modelling groups involved in JRA3. Finally
Quicklook images are currently available within ACTRIS/EARLINET community for
testing this facility before opening it to the public.

##  Cloud remote sensing data sets

Cloud profile data are qualified as ACTRIS data only if

  * The atmospheric profile variables are included in the list in Appendix 1 

  

  * The processing applied complies with the procedures and recommendations provided by the ACTRIS community harmonised with Cloudnet. 

  

  * The data are reported to the Cloudnet DB in accordance with the reporting procedures 

  

Standard collection and reporting procedure for cloud profile data

  * Utilise the Cloudnet processing scheme. 

  

  * Preliminary data is accessible immediately to the community and public on insertion into the Cloudnet DB, together with a statement their appropriateness and validity for use. 

  

  * All data undergoes an approval process for final publishing, cognisant with full periodic calibration assessment and approval by expert panel. 

  

  * Selected variables are provided in NRT for the purposes of assimilation and NRT evaluation of NWP model data. 

  

##  ACTRIS level 3 data products and digital data tools

ACTRIS level 3 data are elaborated ACTRIS data products derived by post-
processing of ACTRIS Level 0 -1

-2 data, as described in section 2.1-2.3, and data from other sources. ACTRIS level 3 data and project data tools can also include codes, algorithms and software used to generate ACTRIS data, level 0-level 3. Whereas level 0-1-2 datasets are regularly updated mainly due to the collection of new measurements and extension of the time series, level 3 datasets are not updated regularly. Level 3 are usually the result of targeted analysis, special studies, case studies, or processed for model experiments, including work performed under ACTRIS Joint Research Activities, and Transnational Access. The next section give some examples. 

###  Advanced products based on aerosol and trace gas in situ data sets

Advanced products based on aerosol and trace gas in situ data sets will be
developed in collaboration with joint research activities and in accordance
with other scientific requests during the project. Standard advanced products
can include typically aggregated data such as daily, monthly or annual means
of selected variables. Furthermore, the potential of long-term high quality
ACTRIS-2 data for understanding of trends in atmospheric composition is
further developed. A methodology will be put in place to analyse and produce
site-specific and regional trends. Suitable in situ variables are particle
size, and particle optical properties. Additionally, online QA tools and
products is offered for checking the consistency of the data sets in terms of
ratios between specific trace gases, and closure tests between aerosol
variables from different instruments.

###  Advanced products based on aerosol remote sensing data sets

Advanced data products will be designed time by time following the specific
needs as they are results of specific studies. Advanced data are stored and
made freely available at EARLINET database as advanced products. These are the
results of devoted (typically published) studies. Standard advanced products
include climatological products from long-term observations. Further advanced
products can be the results of JRA as microphysical aerosol products based on
inversion of multi-channel lidar data, and microphysical aerosol products from
combined lidar and sun-photometer observations. In particular, ICARE will
automatically process raw lidar data from the EARLINET DB, combined with
coincident AERONET data, using the GARRLiC (Generalized Aerosol Retrieval from
Radiometer and Lidar Combined data) algorithm to retrieve vertical profiles of
aerosol properties.

Currently 2 advanced product datasets are available for the aerosol remote
sensing component: a datasets about aerosol masking and typing for the case of
2010 Eyjafjallajökull volcanic cloud, and the EARLINET 72h operativity
exercise dataset.

###  Advanced products based on cloud profile data sets

Advanced data products are prepared automatically by the Cloudnet processing
scheme include model evaluation datasets, and diurnal/seasonal composites. In
addition, advanced classification and products will be available from certain
sites, and from campaigns, where additional instruments and products are
combined.

###  Data sets resulting from combined activities with external data providers

The ICARE data centre routinely collects and produces various satellite data
sets and model analyses that are used either in support of ground-based data
analysis or in combination with ground-based data to generate advanced derived
products. These data sets will be channelled to the ACTRIS portal using
colocation and extraction/sub setting tool.

##  The ACTRIS user community

The ACTRIS user community can be classified as primary users (direct users of
ACTRIS data, data products and services) and secondary users (using results
from primary users, e.g. from international data centres). These are both
internal and external users. In general, the user community can be summarized
into five groups:

  1. **Atmospheric science research community.** Together with atmospheric chemistry and physics, this also includes climate change research and meteorology, as well as multidisciplinary research combining these aspects (such as air quality, and climate interactions with links between aerosols, clouds and weather). 

  

  2. **Research communities in neighbouring fields of research.** These are environmental and ecosystem science, marine science, geosciences/geophysics, space physics, biodiversity, health and energy research. These communities will benefit from ACTRIS through the longterm provision of high-quality data products and through the enhanced capacity to perform interdisciplinary research. 

  

  3. **Operational observation and data management.** This community includes international data centres and international programmes to which ACTRIS contributes via the provision of longterm and consistent high-quality data products. Many research programmes and operational services (such as the Copernicus Atmosphere Monitoring and Climate Services) use ACTRIS to produce reliable data. 

  

  4. **Industry and private sector users** . These benefit from the services and high quality standards of the ACTRIS Calibration Centres, and from the free and open access to data products. 

  

  5. **Legislative / policy making community** . This include the user groups within climate, air quality and environmental issues including actors from local organisations, through national governments, to international conventions and treaties (including IPCC and UNFCCC, and UNECE-CLRTAP via the link to EMEP). This user community uses ACTRIS research results to define, update and enhance knowledge for decision making, policy topic preparation and drafting response and mitigation policies. 

  

  

#  ACTRIS data set references and names

ACTRIS works towards establishing traceability for all applicable variables.
In collaboration with partners in the ENVRI  plus  project, ACTRIS is working
towards use of digital object identifiers (DOIs), in order to assure proper
attribution is given to data originators adequately reflecting their
contributions.

Generally, ACTRIS data set names aim to be compliant with CF (Climate and
Forecast) conventions. In the case where no standard CF names are defined, an
application will be sent to establish these.

##  Aerosol and trace gas in situ data set references and names

The in situ data set names are listed in Appendix I. For most in situ
variables, ACTRIS data are traceable from the final data product back to the
time of measurement. Traceability is implemented by a series of data levels
leading from curated, instrument specific raw data to the final, automatically
and manually quality assured data product. Processing steps between data
levels are documented by SOPs.

All submissions of in situ data passing quality assurance are uniquely
identified in the EBAS database with a unique dataset identity numbers, ID-
numbers. In case of updates, a ID-number is generated, and previous data
versions are kept available upon request while the latest version is served
through the database web-interface. Defined requests from the data holdings
are identified in the web-interface by unique URLs that allow external links
to the data.

##  Aerosol remote sensing data set references and names

The aerosol profile data set names are listed in Appendix I. The use of SCC
allows the full traceability of the data: SSC converts individual instrument
raw signals into standardized and quality-assured preprocessed lidar data. The
SCC tool will be used to develop a harmonised network-wide, open and freely
accessible quicklook database (high-resolution images of time-height cross
sections). The standardized pre-processed data will also serve as input for
any further processing of lidar data, within the SCC as well as in other
processing algorithms (e.g., combined retrievals with sun photometer, combined
retrievals with Cloudnet).

All aerosol profiles passed through quality check inspections manual and/or
automatic leading to biannual final publication of quality checked data
collection with DOI assignment. The DOI is assigned through the publication on
the CERA database. In case of updates, only the latest version of data is
available at  _http://access.earlinet.org_ and a new collection of data (with
new DOI) is published. Previous data versions are kept available. The
versioning of the EARLINET database is currently in a new design phase:
different versions of data because of different processing and different QC
procedures will be available. The new design in this context will allow having
simultaneously available different versions of data and to track all the
quality control procedures.

##  Cloud profiles

The cloud profile data set names are listed in Appendix I. The common use of
the Cloudnet processing scheme ensures full traceability of the data from raw
individual instrument measurements through to a combined standardised and
quality-assured processed data set. The Cloudnet processing scheme ensures
harmonisation of products across a relatively heterogeneous network. All
quicklooks are open and freely accessible a  t
_http://cloudnet.fmi.fi/quicklooks/_

It is envisaged that publication of curated datasets with DOI assignment will
commence as soon as possible. Currently, only the latest data version is
available throug  h _http://cloudnet.fmi.fi/_ d  ue to the large data volume
requirements.

#  ACTRIS Standards and metadata

ACTRIS standards and metadata systems are well-developed, with variable
standardization already existing in most cases. If this is not the case,
ACTRIS, as a leading community in this field of atmospheric science, will work
in collaboration with WMO-GAW, EMEP and other EU-funded projects (such as
ENVRI  plus  ) in order to set the standards and foster interoperability
between both the large variety of data products developed with ACTRIS itself,
and with respect to external data centres.

##  Standard operating procedures, recommendations and metadata for aerosol
and trace gas in situ data

All aerosol and trace gas in situ data sets are archived and provided in the
NASA-Ames 1001 format.

###  Regular quality-assured data

Standards, SOPs and recommendations for each in situ variable measured within
ACTRIS are listed here for aerosols:
_http://actris.nilu.no/Content/?pageid=13d5615569b04814a6483f13bea96986_ and
here for trace gases
_http://actris.nilu.no/Content/?pageid=68159644c2c04d648ce41536297f5b93_ and
made public available for all.

_**Metadata:** _ A comprehensive metadata system and description of each
ACTRIS in situ variable is implemented in the topic data base EBAS. All ACTRIS
in situ variables are reported to EBAS by using the reporting templates
recommended by the ACTRIS in situ community, harmonized with
GAWrecommendations. The templates ensure that the measurements are reported in
accordance with the procedures for the employed instrument, and include all
the necessary metadata required to precisely describe the measurements,
including uncertainty/percentiles. In this way, all ACTRIS in situ data are
accompanied by a sufficient documentation of the measurements to have in-depth
information on the quality of the data. Information about the reporting
procedure and metadata items are open accessible and available through
_http://ebas-submit.nilu.no_ .  Metadata are interconnected with GAWSIS and
the ACTRIS data centre handling of metadata is INSPIRE and WIS-ready.

###  Near-real-time (NRT) data

Near-real-time (NRT) data flow is offered to the data originators as daily
quality check for selected variables, with the possibility for an alert system
for outliers, instrumental failures and inconsistencies. NRT data collection
and dissemination is available for the in situ ACTRIS observables as
identified in Appendix I.

Participating stations submit their data as annotated raw data in hourly
submissions starting and ending at the turn of an hour. As an exception,
3-hourly submissions are accepted if indicated by limited connectivity with
the station. The raw data are auto-processed to hourly averages, while periods
with obvious instrument malfunctions are disregarded. Special sampling
conditions or transport episodes are not flagged. The processed NRT data are
available through the EBAS web-interface or through autoupdated custom FTP
extracts.

##  Standards and metadata for aerosol profiles

Aerosol profiles data are archived and provided in netCDF format. All
published EARLINET data are in CF (Climate and Forecast) 1.5 compliant format.
A migration for all the data to this convention is planned.

Standards, SOPs and recommendations for aerosol profile data measured within
ACTRIS are listed here:

_http://actris.nilu.no/Content/?pageid=37df0131f7384f70a668e48f4e593278_

_**Metadata:** _ All aerosol profile data are accompanied by respective
metadata reporting information about the station, the system, and the timing
of the measurements. Aerosol profile data sets reported to the ACTRIS data
centre can be the results of regular operation of the EARLINET network, but
also related to specific campaigns and joint research activities. Homogeneous
and well-established quality of data originating from different systems is
assured through a rigorous quality assurance program addressing both
instrument performance and evaluation of the algorithms. Information about the
QA program are summarized in Pappalardo et al., AMT, 2014 and are open and
freely available at  _http://www.atmosmeas-
tech.net/7/2389/2014/amt-7-2389-2014.html_ ACTRIS-2 improvement of the SCC is
a step forward to complete harmonization of the aerosol profiles data quality.
First quality control procedures have been developed in NA2 in collaboration
with the data centre for checking technical consistency with database rules
and format, and checking the data optical properties consistency and through
the comparison with climatological data. All QC tools are available to all
potential contributors of ACTRIS database, both internal and external. The SCC
is currently available to all ACTRIS aerosol remote sensing data originators.
Some collaborations with external users already exist and the SCC will be
opened to the external users.

###  Near-real-time (NRT) data

A standardized and harmonized quicklook interface has been developed for an
open and freely accessible quicklook database under WP2 and has been made
internally available in May 2017. After a testing period some visualization
issues are under fixing. Aerosol remote sensing quicklooks will be made
operational and available through the ACTRIS data portal by April 2018.

Apart from the quicklook images, numerical near real time data will be soon
made available to specific users thanks to a Data Distribution Consensus form
set up by the data centre and filled in by station PIs.

##  Standards and metadata for cloud profiles

###  Quality-assured data

Cloud profiles are archived and provided in netCDF format, with CF–compliant
metadata.

The base-line SOPs and recommendations for Cloudnet variables is given in
Illingworth et al., (2007), with updates given in ACTRIS-FP7 Deliverable D5.10  
  
<table>  
<tr>  
<th>

**Variable**

</th>  
<th>

**Reference SOP and recommendations**

</th> </tr>  
<tr>  
<td>

Cloud and aerosol target classification

</td>  
<td>

Illingworth et al., BAMS, 2007

</td> </tr>  
<tr>  
<td>

Drizzle products

</td>  
<td>

ACTRIS-FP7 Deliverable D5.7, see also O’Connor et al., JTECH, 2005

</td> </tr>  
<tr>  
<td>

Ice water content

</td>  
<td>

Hogan et al., JAMC, 2006

</td> </tr>  
<tr>  
<td>

Liquid water content

</td>  
<td>

Illingworth et al., BAMS, 2007

</td> </tr>  
<tr>  
<td>

Liquid water path

</td>  
<td>

MWRNET,  _http://cetemps.aquila.infn.it/mwrnet/_ see also Gaussiat et al.,
JTECH, 2007

</td> </tr>  
<tr>  
<td>

Higher-level metrics

</td>  
<td>

ACTRIS-FP7 Deliverable D5.10

</td> </tr> </table>

_**Metadata:** _ Cloud profile data are accompanied by metadata describing the
station, instrument combination and supporting ancillary measurements, and
processing software version. Metadata describing instrument calibration
history will be implemented within ACTRIS-2. Harmonization and rigorous
quality control for data originating from different instruments and instrument
combinations is achieved through the common use of the Cloudnet processing
software, summarised in Illingworth et al. (2007). All metadata is propagated
through to every cloud product derived from the measurements; this requirement
will be mandated for all new products derived during ACTRIS-2. The Cloudnet
processing scheme, and the interface description for generating new products,
is freely available for all potential users of ACTRIS data, whether internal
or external.

###  Near-real-time (NRT) data

All cloud NRT data is processed in the same manner as for quality-assured
data, together with all accompanying metadata. However, subsequent instrument
calibration may require reprocessing to generate a revised product, which uses
the updated calibration values.

#  Sharing of ACTRIS data sets and data products

##  Access to ACTRIS data sets and data products

The ACTRIS Data Centre compile, archive and provide access to all ACTRIS data,
and the ACTRIS data portal (  _http://actris.nilu.no_ )  is giving free and
open access to data resulting from the activities of the ACTRIS
infrastructure, including advanced data products resulting from ACTRIS
research activities. Every dataset created within ACTRIS is owned by the
ACTRIS partner(s) who created this dataset. _The ACTRIS Data Policy (_ _
http://actris.nilu.no/Content/Documents/DataPolicy.pdf)  _ regulates the
sharing and use of ACTRIS data, see section 5.3.

The ACTRIS data portal (  _http://actris.nilu.no_ )  provide access to ACTRIS
data sets. This is a virtual research environment with access to all data from
ACTRIS platforms and higher level data products resulting from scientific
activities. The portal is structured as a metadata catalogue, searching the
topical data bases, enabling data download from the primary archive and
combination of data across the primary data repositories. The metadata
catalogue is updated every night, providing access to all recent ACTRIS data.
All data are archived in the topical data repositories, to  1)  maintain
access to last version of data,  2)  avoid duplications and  3)  keep full
traceability of the data sets.

###  Aerosol and trace gas in situ data repository

The ACTRIS data repository for all aerosol and trace gas in situ data is EBAS
. _http://ebas.nilu.no_ .  The web portal is set up on a dedicated linux
server running in Python program language. EBAS is an atmospheric database
infrastructure where open access to research data has developed over almost 45
years and the data infrastructure is developed, operated, and maintained by
NILU - Norwegian Institute for Air Research. The main objective of EBAS is to
handle, store and disseminate atmospheric composition data generated by
international and national frameworks to various types of user communities.
Currently, EBAS is a data repository for ACTRIS, and also hosts the World Data
Centre of aerosols under WMO Global Atmosphere Watch (GAW) and data from
European Monitoring and Evaluation Programme (EMEP) under the UN Convention
for Long-Range Transport of Air Pollution (CLRTAP), among other frameworks and
programmes.

No embargo times apply to these data; all data is reported to EBAS as early as
possible, and no later than 31 July the following year of the measurement. The
data sets are made available to all users as soon as possible after quality
control and quality assurance.

###  Aerosol profile data repository

The ACTRIS data repository for all aerosol profile data is
_http://access.earlinet.org_ .  The aerosol profile database is hosted,
maintained and operated by CNR-IMAA (National Research Council-Institute of
Methodologies for Environmental Analysis) where the Single Calculus Chain for
the automatic processing of lidar data for aerosol optical properties
retrieval was designed, optimized and operated for the whole network. CNR-IMAA
hosts different advanced products developed by EARLINET in the past for
providing access to external users (volcanic eruption products, satellite
validation datasets and NRT EARLINET subsets).

Aerosol profiles data are regularly published on the CERA database, following
the first database publications of EARLINET database. This assures the
discoverability of the data through the association of a DOI to the data and
the archiving on CERA, a recognized official repository. A different data
granule is under investigation for the future for allowing a better
recognition to the different stations.

The ACTRIS/EARLINET database is also accessible through THREDDS (Thematic
Real-time Environmental Distributed Data Services).

###  Cloud profile data repository

The ACTRIS data repository for all cloud profile data is
_http://cloudnet.fmi.fi_ .  The cloud profile database is currently hosted,
maintained and operated by FMI (Finnish Meteorological Institute). The
database provides the capability for both in-house processing of instrument
data, and collection of on-site processed data through distributed use of the
Cloudnet processing scheme. Both NRT access (e.g. model evaluation) and full
quality-assured archived data access is available for internal and external
users.

No embargo is applied to data quicklooks, available in NRT when possible. An
embargo is generally only applied to data when a site is in testing mode (new
instrumentation or re-calibration of existing instrumentation). Otherwise all
data sets are immediately available in NRT-mode (no QA) or as soon as quality
control/assurance has been applied. During the course of ACTRIS-2 quality-
assured archived datasets will be published in a recognized official
repository with an associated DOI.

##  Access to level 3 data and combined data products

ACTRIS level 3data sets are stored in dedicated catalogue in the ACTRIS Data
Centre or specified in the ACTRIS topical databases to provide long term
access for all users. Access to these data sets and products is made available
through the ACTRIS data portal:  _http://actris.nilu.no_ .

The ICARE Data and Services Centre is hosted by the University of Lille in
partnership with CNRS and CNES. ICARE routinely collects various data sets
from third party data providers (e.g., space agencies, meteorological
agencies, ground-based observation stations) and generates a large number of
derived products. All data sets are available for download at
_http://www.icare.univ-lille1.fr/catalogue_ through direct FTP access or web-
based services, upon receipt or upon production, some of them in NRT. In
addition, ICARE provides visualisation and analysis tools (e.g.  ,
_http://www.icare.univ-lille1.fr/browse_ )  , and tools to co-locate and
subset data sets at the vicinity of ground-based observation networks  (
_http://www.icare.univ-lille1.fr/extract_ )  . Existing tools will be fine-
tuned to meet specific ACTRIS requirements. Access to selected data and
services will be facilitated through the ACTRIS portal.

No embargo is applied to data quicklooks. Most data sets are freely available
for download upon registration. Some restrictions in data access or data use
may be inherited from original data providers or algorithm PIs for
experimental products generated at ICARE.

##  The ACTRIS Data Policy

The ACTRIS Data Policy regulates the sharing of ACTRIS data and includes
information on dissemination, sharing and access procedures for various types
of data and various user groups. The ACTRIS Data Policy is publically
available from the ACTRIS web site, from the ACTRIS Data Centre, and here:

_http://actris.nilu.no/Content/Documents/DataPolicy.pdf_

The 1  st  version of the ACTRIS Data Policy was established under ACTRIS-FP7,
June 2012. The 2  nd  version was approved by ACTRIS-2 SSC, September 2015.

#  Archiving and preservation of ACTRIS data sets

The main structure and installations of the ACTRIS Data Centre is located at
_NILU - Norwegian Institute for Air Research_ , Kjeller, Norway. NILU hosts
EBAS archiving all in situ data sets, in addition to the ACTRIS Data Portal.
The other installations are the EARLINET DB at _National Research Council -
Institute of Environmental Analysis_ (CNR), Tito Scalo, Potenza, Italy, the
satellite data components at the _University of Lille_ , Villeneuve d'Ascq,
France, and the cloud profile data in the Cloudnet DB at the _Finnish
Meteorological Institute_ in Helsinki, Finland.

##  Aerosol and trace gas in situ data

EBAS is a relational database (Sybase) developed in the mid-1990s. Data from
primary projects and programmes, such as ACTRIS, GAW-WDCA, EMEP, AMAP, are
physically stored in EBAS. All data in EBAS are, in addition, stored at a
dedicated disk in the file tree at NILU. This include the levels 0-1-2 of
data.

The complete data system is backed up regularly. This includes incremental
back up of the data base 6 times per week, and one weekly back up of the full
data base to a server in a neighbour building to ensure as complete as
possible storage of all data for future use in case of e.g. fires or other
damages to the physical construction. File submission is conducted by ftp. A
separate ftp area is allocated to incoming files, and all activities herein
are logged on a separate log file, and backed up on 2 hour frequency. An alert
system is implemented to ensure warning messages if there are problems during
file transfer from the data originators to the data centre.

Ca 455 separate new comprehensive files including meta data with annual time
series of medium to high time resolution (seconds to week) is expected per
year. A significant growth in this number is not expected on annual scale. In
total this will sum up to ca 10GB/year from ca 150 000 single column files,
including both raw data and auxiliary parameters.

EBAS is based on data management over more than 40 years. Last 10 years there
has been a European project-type cooperation from FP5 to Horizon2020, with and
EMEP and GAW programmes since 1970’s as the fundament. Sharing visions and
goals with the supporting long-term policy driven frameworks have ensured
long-term funding for the core data base infrastructure. A long-term strategy
for providing access to all ACTRIS data and other related services are in
progress through the establishment of ACTRIS as a RI. ACTRIS is on the ESFRI
(European Strategy Forum on Research Infrastructures) roadmap for Research
Infrastructures, and a preparatory phase project is ongoing.

##  Aerosol profiles

The storage infrastructure is composed by three servers and two different SAN
(Storage Area Network). One server hosts the EARLINET PostgreSQL database and
the other one is used to interface both end-users and data submitters to the
EARLINET database. This last server is connected to the operational SAN on
which the data submitted by the user are safety stored. A daily back up of the
EARLINET database is made automatically and it is stored on the second backup
SAN.

The whole EARLINET database is also accessible through THREDDS (Thematic Real-
time Environmental Distributed Data Services) which is installed on a third
server. On the same server a CAS (Central Authentication Service) is configure
to authenticate all EARLINET users centrally.

The current size of the PostgresSQL EARLINET database is about 1GB. The total
amount of data submitted (NetCDF EARLINET files) is about 1.3 GB. An
estimation of the growing rate of the database at this rate is 100-200MB/year.
However a significant growth in number of files to be collected is expected
because of: the use of the SCC (Single Calculus Chain) for the data
submission, the inclusion of new products (preprocessed data, NRT optical
properties, profiles, aerosol layers properties and multi-wavelength
datasets), increases of the number of EARLINET stations and increase of
EARLINET h24 stations. We estimate that at the end of ACTRIS2 project, the
ACTRIS aerosol profile database could growth at a rate of about 12-15 GB per
year.

The SCC is part of the EARLINET data centre and it is the standard EARLINET
tool for the automatic analysis of lidar data. Three additional servers are
needed to provide this further service: a calculus server where all the SCC
calculus modules are installed and ran, a MySQL database where all the
analysis metadata are stored in a fully traceable way a finally a web
interface allowing the users to access to the SCC.

The EARLINET database and the SCC are maintained by the National Research
Council of Italy with long term commitment for archiving and preservation. The
archiving on CERA database is a further measure for assuring the availability
of the data through redundancy of the archive.

##  Cloud profiles

The Cloudnet database is a file-based database, due to the nature of the
typical use-case and data volume. The infrastructure comprises an FTP server
for incoming data streams, rsync server for outgoing data streams, processing
server, webserver, with data storage distributed across a series of virtual
file-systems including incremental backups. Due to the data volume, most sites
also hold a copy of their own processed data, effectively acting as a second
distributed database and additional backup.

The current size of the database is about 10 TB and the volume is expected to
grow by close to 0.5 TB per year with the current set of stations and the
standard products. However, there will be a significant increase in volume
when the planned move to multi-peak and spectral products is undertaken; this
is in addition to a slight increase arising through the creation of new
products. The Cloudnet database is maintained by FMI with long-term commitment
for archiving and preservation. Publication of QA datasets will aid dataset
preservation.

#  ACTRIS Data Centre− Organisation and personal resources

The ACTRIS Data Centre involves personal with broad and complementary
background and competence. In total, more than 25 persons are involved in the
data management, on full or part time.

A crucial structure of the ACTRIS data centre is the use of topical data
service centres involving by scientists with expertise in the relevant field.
This ensures not only proper curation of the data but also a close connection
to the data provider and user communities. A topical data centre run by
scientists with data curation expertise serves as identifying elements built
jointly with the data provider community, and as connecting element between
data providers and users. The fundamental structure of the data centre is
based on efficient use of complementary competence. This includes involvements
of senior scientists, young scientists, engineers, programmers, and data base
developers. A data centre serving several related communities, e.g. scientific
and regulatory ones, are facilitating exchange and collaboration between
these. Additionally, involvement of senior scientists working actively within
various scientific communities is another pre-requisite, to ensure the links
to various scientific user groups, for distribution of data products, and user
oriented development of the data centre.

The ACTRIS data portal acts as umbrella for the topical data centres allowing
search, download, and common visualisation of the data archived at the topical
data centres. Maybe even more important, it will also connect ACTRIS with
other European and international research data centres by allowing the same
services for the data stored there by making use of latest inter-operability
specifications. Also at the administrative plain, the ACTRIS portal represents
the infrastructures in the relevant bodies working a unifying data management,
and relays new developments to the whole infrastructure.

#  Appendix I:List of ACTRIS variables and recommended methodology  
  
<table>  
<tr>  
<th>

**ACTRIS Aerosol particle variables**

**Variable name**

</th>  
<th>

**Recommended methodology**

</th>  
<th>

**Validated data**

</th>  
<th>

**NRT**

</th>  
<th>

**Typical time res.**

</th>  
<th>

**Higher timeres. available**

</th> </tr>  
<tr>  
<td>

**In situ aerosol particle variables**

</td>  
<td>

</td>  
<td>

</td>  
<td>

</td>  
<td>

</td>  
<td>

</td> </tr>  
<tr>  
<td>

Particle light scattering coefficient

</td>  
<td>

Integrating Nephelometer

</td>  
<td>

X

</td>  
<td>

X

</td>  
<td>

1h

</td>  
<td>

X

</td> </tr>  
<tr>  
<td>

Particle light backscattering coefficient

</td>  
<td>

Integrating Nephelometer

</td>  
<td>

X

</td>  
<td>

X

</td>  
<td>

1h

</td>  
<td>

X

</td> </tr>  
<tr>  
<td>

Particle number size distribution

</td>  
<td>

Mobility particle size spectrometer (e.g. differential mobility particle size,
scanning mobility particle sizer) or Optical particle size spectrometer (e.g.
optical particle counter, optical particle sizer) or Aerodynamic particle size
spectrometer (e.g. aerodynamic particle sizer)

</td>  
<td>

X

</td>  
<td>

X

</td>  
<td>

1h

</td>  
<td>

X

</td> </tr>  
<tr>  
<td>

Particle light absorption coefficient

</td>  
<td>

Filter Absorption Photometer (e.g. Particle Soot/Absorption

Photometer, Multi-Angle Absorption Photometry, Aethalometer)

</td>  
<td>

X

</td>  
<td>

X

</td>  
<td>

1h

</td>  
<td>

X

</td> </tr>  
<tr>  
<td>

Particle number concentration

</td>  
<td>

Condensation Particle Counter

</td>  
<td>

X

</td>  
<td>

X

</td>  
<td>

1h

</td>  
<td>

X

</td> </tr>  
<tr>  
<td>

Cloud condensation nuclei number concentration

</td>  
<td>

Condensation Cloud Nuclei Counter

</td>  
<td>

X

</td>  
<td>

X(later)

</td>  
<td>

1h

</td>  
<td>

X

</td> </tr>  
<tr>  
<td>

Hygroscopic growth factor

</td>  
<td>

Hygroscopicity Tandem Differential Mobility Analyzer

</td>  
<td>

X

</td>  
<td>

</td>  
<td>

1h

</td>  
<td>

X

</td> </tr>  
<tr>  
<td>

Particulate organic and elemental carbon mass concentrations (OC/EC)

</td>  
<td>

Filter sampling + evolved gas analysis with optical correction for charring
(thermal-optical analysis)

</td>  
<td>

X

</td>  
<td>

</td>  
<td>

1d-1week

</td>  
<td>

</td> </tr>  
<tr>  
<td>

Particulate size-resolved chemical composition

(organic & inorganic size-resolved mass speciation)

</td>  
<td>

Aerosol Mass Spectrometer, Aerosol Chemical Speciation Monitor

</td>  
<td>

X

</td>  
<td>

</td>  
<td>

1h

</td>  
<td>

X

</td> </tr>  
<tr>  
<td>

Particulate levogluocsan mass concentration

</td>  
<td>

Filter sampling + offline methodology

</td>  
<td>

X

</td>  
<td>

</td>  
<td>

1d-1week

</td>  
<td>

</td> </tr> </table>  
<table>  
<tr>  
<th>

**ACTRIS in situ trace gas variables**

**Variable**

</th>  
<th>

**Recommended methodology**

</th>  
<th>

**Validated data**

</th>  
<th>

**NRT**

</th>  
<th>

**Approx. time resolution**

</th> </tr>  
<tr>  
<td>

NMHCs (C2-C9 hydrocarbons) _*See detailed list_

</td>  
<td>

on-line: GC-FID, GC-MS, GS-FID/MS, GC-Medusa, PTR-MS off-line traps: ads-tubes

off-line: steel canisters + glass flasks, combined with the on-line
instruments in laboratories

</td>  
<td>

X

</td>  
<td>

</td>  
<td>

1 h-2/week

</td> </tr>  
<tr>  
<td>

OVOCs (oxidised volatile organic compounds as aldehydes, ketons, alcohols,)
_See detailed list of the compounds at the end of the document_

</td>  
<td>

on-line: GC-FID, GC-MS, GS-FID/MS, GC-Medusa, PTR-MS off-line traps: ads-
tubes, DNPH-cartridge-HPLC

</td>  
<td>

X

</td>  
<td>

</td>  
<td>

1 h-2/week

</td> </tr>  
<tr>  
<td>

Terpenes (biogenic hydrocarbons with a terpenestructure) _*See detailed list
at the end of the document_

</td>  
<td>

on-line (GC-FID, GC-MS, GS-FID/MS, GC-Medusa) and off-line traps (adstubes)

</td>  
<td>

X

</td>  
<td>

</td>  
<td>

1 h-2/week

</td> </tr>  
<tr>  
<td>

NO

</td>  
<td>

NO-O  3  chemiluminescence

</td>  
<td>

X

</td>  
<td>

X

</td>  
<td>

1 min - 1 h

</td> </tr>  
<tr>  
<td>

NO2

</td>  
<td>

indirect: NO-O  3  chemiluminescence coupled to photolytic converter

(Xenon lamp (PLC) or diode (BLC)),

direct: cavity ring down spectroscopy (CRDS), laser induced fluorescence
(LIF), Cavity Attenuated Phase Shift Spectroscopy (CAPS)

</td>  
<td>

X

</td>  
<td>

X

</td>  
<td>

1 min - 1 h

</td> </tr>  
<tr>  
<td>

NOy (NO, NO2, NO3, N2O5, HNO2, HNO3, PAN, organic nitrates and aerosol
nitrates sum of oxidized nitrogen species with an oxidation number >1, both
organic and inorganic.)

</td>  
<td>

indirect: NO-O3 chemiluminescence coupled to gold converter

</td>  
<td>

X

</td>  
<td>

X

</td>  
<td>

1 min - 1 h

</td> </tr> </table>  
<table>  
<tr>  
<th>

**ACTRIS Aerosol particle variables**

</th>  
<th>

</th>  
<th>

</th>  
<th>

</th> </tr>  
<tr>  
<td>

**Variable name**

</td>  
<td>

**Recommended methodology**

</td>  
<td>

**Validated data**

</td>  
<td>

**NRT**

**Approx. time resolution**

</td> </tr>  
<tr>  
<td>

**Aerosol remote sensing variables**

</td>  
<td>

</td>  
<td>

</td>  
<td>

</td> </tr>  
<tr>  
<td>

Aerosol backscatter coefficient profile

</td>  
<td>

Backscatterlidar / Raman lidar/Highspectral resolution lidar

</td>  
<td>

X

</td>  
<td>

0.5 h, 2+1 measur. per week + special events

\+ CALIPSO overpasses (2.5 h)

</td> </tr>  
<tr>  
<td>

Aerosol extinction coefficient profile

</td>  
<td>

Raman lidar / High spectral resolution lidar

</td>  
<td>

X

</td>  
<td>

0.5 h, 2+1 measur. per week + special events

\+ CALIPSO overpasses (2.5 h)

</td> </tr>  
<tr>  
<td>

Lidar ratio profile*

</td>  
<td>

Raman lidar / High spectral resolution lidar

</td>  
<td>

X

</td>  
<td>

0.5 h, 2+1 measur. per week + special events

\+ CALIPSO overpasses (2.5 h)

</td> </tr>  
<tr>  
<td>

Ångström exponent profile*

</td>  
<td>

Multiwavelength Raman lidar

</td>  
<td>

X

</td>  
<td>

0.5 h, 2+1 measur. per week + special events

\+ CALIPSO overpasses (2.5 h)

</td> </tr>  
<tr>  
<td>

Backscatter-related Ångström exponent profile*

</td>  
<td>

Multiwavelengthbackscatterlidar / Raman lidar

</td>  
<td>

X

</td>  
<td>

0.5 h, 2+1 measur. per week + special events

\+ CALIPSO overpasses (2.5 h)

</td> </tr>  
<tr>  
<td>

Particle depolarization ratio profile

</td>  
<td>

Depolarization backscatter lidar

</td>  
<td>

X

</td>  
<td>

0.5 h, 2+1 measur. per week + special events

\+ CALIPSO overpasses (2.5 h)

</td> </tr>  
<tr>  
<td>

Particle layer geometrical properties (height and thickness)*

</td>  
<td>

Backscatterlidar / Raman lidar/ Highspectral resolution lidar

</td>  
<td>

X

</td>  
<td>

0.5 h, 2+1 measur. per week + special events

\+ CALIPSO overpasses (2.5 h)

</td> </tr>  
<tr>  
<td>

Particle layer optical properties (extinction, backscatter, lidar ratio,
Ångström exponent, depolarization ratio, optical depth)*

</td>  
<td>

Multiwavelength Raman lidar

</td>  
<td>

X

</td>  
<td>

0.5 h, 2+1 measur. per week + special events

\+ CALIPSO overpasses (2.5 h)

</td> </tr>  
<tr>  
<td>

Aerosol optical depth (column)*

</td>  
<td>

Sun/sky photometer

</td>  
<td>

x

</td>  
<td>

x

</td> </tr>  
<tr>  
<td>

Planetary boundary layer height

</td>  
<td>

Backscatterlidar / Raman lidar/ Highspectral resolution lidar

</td>  
<td>

X

</td>  
<td>

0.5 h, 2+1 measur. per week + special events

\+ CALIPSO overpasses (2.5 h)

</td> </tr> </table>

_* these data will be available in the new data products when released_  
  
<table>  
<tr>  
<th>

**ACTRIS cloud variables**

**Variable**

</th>  
<th>

**Recommended methodology**

</th>  
<th>

**Validated**

**data NRT**

</th>  
<th>

**Approx. time /height resolution**

</th> </tr>  
<tr>  
<td>

**Cloud remote sensing variables**

</td>  
<td>

</td>  
<td>

</td>  
<td>

</td>  
<td>

</td> </tr>  
<tr>  
<td>

cloud/aerosol target classification

</td>  
<td>

cloud radar, lidar/ceilometer, NWP model or radiosonde (optional: microwave
radiometer)

</td>  
<td>

X

</td>  
<td>

X

</td>  
<td>

30 seconds / 60 metres

</td> </tr>  
<tr>  
<td>

drizzle drop size distribution

</td>  
<td>

doppler cloud radar, lidar/ceilometer, NWP model or radiosonde (optional:
microwave radiometer)

</td>  
<td>

X

</td>  
<td>

X

</td>  
<td>

30 seconds / 60 metres

</td> </tr>  
<tr>  
<td>

drizzle water content

</td>  
<td>

doppler cloud radar, lidar/ceilometer, NWP model or radiosonde (optional:
microwave radiometer)

</td>  
<td>

X

</td>  
<td>

X

</td>  
<td>

30 seconds / 60 metres

</td> </tr>  
<tr>  
<td>

drizzle water flux

</td>  
<td>

cloud radar, lidar/ceilometer, NWP model or radiosonde (optional: microwave
radiometer)

</td>  
<td>

X

</td>  
<td>

X

</td>  
<td>

30 seconds / 60 metres

</td> </tr>  
<tr>  
<td>

ice water content

</td>  
<td>

cloud radar, lidar/ceilometer, NWP model or radiosonde (optional: microwave
radiometer)

</td>  
<td>

X

</td>  
<td>

X

</td>  
<td>

30 seconds / 60 metres

</td> </tr>  
<tr>  
<td>

liquid water content

</td>  
<td>

cloud radar, lidar/ceilometer, microwave radiometer

</td>  
<td>

X

</td>  
<td>

X

</td>  
<td>

30 seconds / 60 metres

</td> </tr>  
<tr>  
<td>

liquid water path

</td>  
<td>

dual- or multi-frequency microwave radiometers (ceilometer useful for
identifying clear-sky)

</td>  
<td>

X

</td>  
<td>

X

</td>  
<td>

30 seconds

</td> </tr>  
<tr>  
<td>

rainrate

</td>  
<td>

drop-counting raingauge or disdrometer preferable to tipping bucket raingauges

</td>  
<td>

X

</td>  
<td>

X

</td>  
<td>

30 seconds

</td> </tr>  
<tr>  
<td>

**Cloud in situ variables**

</td>  
<td>

</td>  
<td>

</td>  
<td>

</td>  
<td>

</td> </tr>  
<tr>  
<td>

Liquid Water Content

</td>  
<td>

In-situ cloud-microphysical sensors

</td>  
<td>

X

</td>  
<td>

</td>  
<td>

5 min

</td> </tr> </table>  
<table>  
<tr>  
<th>

**Detailed list of trace gases included in ACTRIS -** _Alkanes, Alkenes,
Alkynes_

</th>  
<th>

</th> </tr>  
<tr>  
<td>

**Alkanes**

</td>  
<td>

ethane

</td>  
<td>

2-methylhexane n-heptane 2-2-4trimethylpentane 3-methylheptane

</td>  
<td>

**Alkenes**

</td>  
<td>

ethene propene trans-2-butene

1-butene

</td>  
<td>

**Alkynes**

</td>  
<td>

ethyne

</td> </tr>  
<tr>  
<td>

propane

</td>  
<td>

proypne

</td> </tr>  
<tr>  
<td>

2-methylpropane

</td>  
<td>

1-butyne

</td> </tr>  
<tr>  
<td>

n-butane

</td>  
<td>

</td>  
<td>

</td> </tr>  
<tr>  
<td>

2-2-dimethylpropane

</td>  
<td>

n-octane n-nonane n-decane methyl-cyclohexane n-undecane

</td>  
<td>

2-methylpropene cis-2-butene

1-3-butadiene

3-methyl-1-butene

2-methyl-2-butene

</td> </tr>  
<tr>  
<td>

2-methylbutane

</td> </tr>  
<tr>  
<td>

n-pentane

</td> </tr>  
<tr>  
<td>

cyclopentane

</td> </tr>  
<tr>  
<td>

methyl-cyclopentane

</td>  
<td>

</td>  
<td>

</td> </tr>  
<tr>  
<td>

2-2-dimethylbutane

</td>  
<td>

n-dodecane n-tridecane n-tetradecane n-pentadecane n-hexadecane

</td>  
<td>

trans-2-pentene cyclopentene 1-pentene cis-2-pentene 1-hexene isoprene

</td>  
<td>

</td>  
<td>

</td> </tr>  
<tr>  
<td>

2-3-dimethylbutane

</td>  
<td>

</td>  
<td>

</td> </tr>  
<tr>  
<td>

2-methylpentane

</td>  
<td>

</td>  
<td>

</td> </tr>  
<tr>  
<td>

3-methylpentane

</td>  
<td>

</td>  
<td>

</td> </tr>  
<tr>  
<td>

cyclohexane

</td>  
<td>

</td>  
<td>

</td> </tr>  
<tr>  
<td>

n-hexane

</td>  
<td>

</td>  
<td>

</td>  
<td>

</td> </tr>  
<tr>  
<td>

methyl-cyclohexane

</td>  
<td>

</td>  
<td>

</td>  
<td>

</td> </tr>  
<tr>  
<td>

2-2-3-trimethylbutane

</td>  
<td>

</td>  
<td>

</td> </tr>  
<tr>  
<td>

2-3-dimethylpentane

</td>  
<td>

</td>  
<td>

</td> </tr>  
<tr>  
<td>

2-2-dimethylpentane

</td>  
<td>

</td>  
<td>

</td> </tr>  
<tr>  
<td>

2-4-dimethylpentane

</td>  
<td>

</td>  
<td>

</td> </tr>  
<tr>  
<td>

3-3-dimethylpentane

</td>  
<td>

</td>  
<td>

</td> </tr>  
<tr>  
<td>

3-methylhexane

</td>  
<td>

</td>  
<td>

</td>  
<td>

</td> </tr> </table>  
<table>  
<tr>  
<th>

**Detailed list of trace gases included in ACTRIS** _\- OVOCs, Terpenes,
Aromatics_

</th>  
<th>

</th> </tr>  
<tr>  
<td>

**OVOCs**

</td>  
<td>

methanol methylethylketon

</td>  
<td>

**Terpenes**

</td>  
<td>

alpha-thujene

</td>  
<td>

**Aromatics**

</td>  
<td>

benzene

</td> </tr>  
<tr>  
<td>

ethanol methacrolein

</td>  
<td>

tricyclene

</td>  
<td>

toluene

</td> </tr>  
<tr>  
<td>

isopropanol methylvinylketon

</td>  
<td>

alpha-pinene

</td>  
<td>

ethylbenzene

</td> </tr>  
<tr>  
<td>

n-propanol glyoxal

</td>  
<td>

camphene

</td>  
<td>

m-p-xylene

</td> </tr>  
<tr>  
<td>

n-butanol methylglyoxal

</td>  
<td>

sabinene

</td>  
<td>

o-xylene

</td> </tr>  
<tr>  
<td>

methyl-butanol butylacetat

</td>  
<td>

myrcene

</td>  
<td>

1-3-5-trimethylbenzene

</td> </tr>  
<tr>  
<td>

formaldehyde acetonitrile

</td>  
<td>

beta-pinene

</td>  
<td>

1-2-4-trimethylbenzene

</td> </tr>  
<tr>  
<td>

acetaldehyde

</td>  
<td>

</td>  
<td>

alpha-phellandrene

</td>  
<td>

1-2-3-trimethylbenzene

</td> </tr>  
<tr>  
<td>

n-propanal

</td>  
<td>

</td>  
<td>

3-carene

</td>  
<td>

</td>  
<td>

</td> </tr>  
<tr>  
<td>

n-butanal

</td>  
<td>

</td>  
<td>

alpha-terpinene

</td> </tr>  
<tr>  
<td>

pentanal

</td>  
<td>

m-cymene

</td> </tr>  
<tr>  
<td>

hexanal

</td>  
<td>

cis-ocimene

</td> </tr>  
<tr>  
<td>

heptanal

</td>  
<td>

p-cymene

</td> </tr>  
<tr>  
<td>

octanal

</td>  
<td>

limonene

</td> </tr>  
<tr>  
<td>

decanal

</td>  
<td>

beta-phellandrene

</td> </tr>  
<tr>  
<td>

undecanal

</td>  
<td>

eucalyptol

</td> </tr>  
<tr>  
<td>

benzaldehyde

</td>  
<td>

gamma-terpinene

</td> </tr>  
<tr>  
<td>

acrolein

</td>  
<td>

terpinolene

</td> </tr>  
<tr>  
<td>

acetone

</td>  
<td>

camphor

</td> </tr> </table>