#  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:

  * Near-surface aerosol and trace gas data are reported to EBAS  : _http://ebas.nilu.no/_ • Aerosol profile data are reported to the EARLINET Data base: 

  

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

  * Cloud profile data are reported to the Cloudnet data base  : _http://www.cloud-net.org/data/_

  

In addition, ICARE 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

ACTRIS data sets are atmospheric variables listed in Appendix I, measured with
the corresponding recommended methodology. Furthermore, the data are qualified
as ACTRIS data sets only if they comply with the additional requirements
specified in section 2.1 -2.3 **.** The list of variables are expected to
increase during the progress of ACTRIS, particularly secondary data 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, andstandardized preprocessed
lidar data and NRT optical property profiles will be available.

##  Aerosol and trace gas near-surface data sets

Aerosol and trace gas near-surface 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 near-surface community. See section 4.1of 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 near-surface community, and available at  _http://ebas-submit.nilu.no_

  

Datasets fulfilling the requirements above qualify for the “ACTRIS” near-
surface 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 near-
surface measurement data:

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

  

  * Data are submitted to a dedicated ftp-server at the data centre 

  

  * 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-WDCGG; 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 profile 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, 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 preprocessed data. 

  

  * New data shall be uploaded to the EARLINET DB within 3 months after measurement by data originator as preliminary data. 

  

  * Preliminary data shall be made accessible to the public as soon as possible, and automatically by the database 1 year after the measurement. 

  

  * All data will pass an approval process within 2 years after being measured. The approval is undertaken by an internal group of experts. During the ACTRIS2 project automatic QC procedures will be implemented and applied starting from these previous experiences. 

  

At the beginning of ACTRIS-2 project, the aerosol vertical profile database
contain aerosol optical properties profiles. During the ACTRIS-2 project, it
will be augmented with more products, providing also information about the
layering, and typing. In addition, standardized preprocessed lidar data and
NRT optical properties profiles will be available.

##  Cloud profile 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 Secondary data products, combined data and project data tools

ACTRIS Secondary data are derived from the primary ACTRIS data described in
section2.1-2.3, by e.g. averaging, filtering of events, interpolation of data
etc. ACTRIS secondary data sets and project data tools can also include codes,
algorithms and software used to generate ACTRIS primary or secondary data.
Whereas primary datasets are regularly updated mainly due to the collection of
new measurements and extension of the time series, secondary datasets are
normally not updated. Secondary datasets 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.They are “single purpose”, i.e. made for one specific
purpose, as opposed to primary data which are documented as to serve as many
purposes as possible.

###  Advanced products based on aerosol and trace gas near-surface data sets

Advanced products based on aerosol and trace gas near-surface 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 shall be
further developed. A methodology will be put in place to analyse and produce
regularly site-specific and regional trends. Suitable near-surface variables
are particle size, and particle optical properties. Additionally, online QA
tools and products will be 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 profile 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.

###  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/subsetting 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 near-surface data set references and names

The near-surface data set names are listed in Appendix I. For most near-
surface 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 near-surface 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 webinterface by unique URLs that allow external links to
the data.

##  Aerosol profiles

The aerosol profile data set names are listed in Appendix I. The EARLINET
database is a version controlled database. The use of SCC allows the full
traceability of the data: SSC converts individual instrument raw signals into
standardized and quality-assured pre-processed lidar data. The SCC tool will
be used to develop a harmonised network-wide, open and freely accessible
quicklook database (highresolution 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.

##  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://www.cloud-
net.org/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://www.cloud-net.org/data/_ due to the large data
volume requirements.

#  ACTRIS Standards and metadata

ACTRIS standards and metadata systems are well-developed, with
parameter/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.

##  Standards and metadata for aerosol and trace gas near-surface data

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

###  Regular quality-assured data

Standards, SOPs and recommendations for each near-surface variable measured
within ACTRIS are listed in the table below.  
  
<table>  
<tr>  
<th>

**Variable**

</th>  
<th>

**Reference SOP and recommendations**

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

Particle light scattering coefficient

</td>  
<td>

GAW report #200

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

Particle light absorption coefficient

</td>  
<td>

GAW report #200

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

Particle number concentration

</td>  
<td>

Wiedensohler et al., Atmos. Meas. Tech., 5, 657-685, 2012,
doi:10.5194/amt-5-657-2012

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

Particle number size distributions (fine fraction)

</td>  
<td>

Wiedensohler et al., Atmos. Meas. Tech., 5, 657-685, 2012,
doi:10.5194/amt-5-657-2012

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

Particle number size distributions (coarse fraction)

</td>  
<td>

ACTRIS protocol in preparation

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

Cloud condensation nuclei number concentration

</td>  
<td>

ACTRIS protocol in preparation

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

Liquid Water Content

</td>  
<td>

ACTRIS protocol in preparation, see also Guyot et al., Atmos. Meas. Tech.
Discuss., 8, 5511-5563, doi:10.5194/amtd-8-55112015, 2015.

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

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

</td>  
<td>

EMEP/CCC (2014) Manual for sampling and chemical analysis.

Chapter 4.22 (Last rev. February 2014). URL:

_http://www.nilu.no/projects/ccc/manual/index.html_ .  See also Cavalli et
al., Atmos. Meas. Tech., 3, 79-89, 2010, doi:10.5194/amt-3-79-2010

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

Particulate size-resolved chemical composition (organic & inorganic
sizeresolved mass speciation)

</td>  
<td>

ACTRIS protocol in preparationSee also Ng, et al., Aerosol Science and
Technology, 45:770-784. 2011,

DOI:10.1080/02786826.2011.560211 and Fröhlichet al., Atmos.

Meas. Tech., 6:3225-3241, 2013, doi:10.5194/amt-6-3225-2013.

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

**Variable**

</td>  
<td>

**Reference SOP and recommendations**

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

Particulate levogluocsan mass concentration

</td>  
<td>

Yttri et al,. Atmos. Meas. Tech., 8, 125–147, 2015, Further ACTRIS
recommendations in preparation.

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

Volatile Organic Compounds (VOCs)

</td>  
<td>

ACTRIS-FP7 Deliverable D4.9:Final SOPs for VOCs measurements

_http://www.actris.net/Portals/97/Publications/quality%20standar_
_ds/WP4_D4.9_M42_30092014.pdf_

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

NO  xy

</td>  
<td>

ACTRIS-FP7 Deliverable D4.10: Standardized operating procedures

(SOPs) for NOxy measurements

_http://www.actris.net/Portals/97/Publications/quality%20standar_
_ds/WP4_D4.10_M42_140919.pdf_

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

_**Metadata:** _ A comprehensive metadata system and description of each
ACTRIS near-surface variable is implemented in the topic data base EBAS. All
ACTRIS near-surface variables are reported to EBAS by using the reporting
templates recommended by the ACTRIS near-surface community, harmonized with
GAW-recommendations. 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 nearsurface 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 throug  h
_http://ebas-submit.nilu.no_ .  Metadata are interconnected with GAWSIS and
the ACTRIS data center 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 near-surface 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.  
  
<table>  
<tr>  
<th>

**Variable**

</th>  
<th>

**Reference SOP and recommendations**

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

Aerosol backscatter coefficient profile

</td>  
<td>

Bockmann et al., Appl. Opt. 2004

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

Aerosol extinction coefficient profile

</td>  
<td>

Pappalardo et al., Appl. Opt. 2004

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

Lidar ratio profile

</td>  
<td>

Pappalardo et al., Appl. Opt. 2004

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

Ångström exponent profile

</td>  
<td>

Pappalardo et al., Appl. Opt. 2004

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

Backscatter-related Ångström exponent profile

</td>  
<td>

Bockmann et al., Appl. Opt. 2004

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

Particle depolarization ratio profile

</td>  
<td>

ACTRIS-FP7 Deliverable D2.7, see also Freudenthaler et al., Tellus, 2008

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

Planetary boundary Layer

</td>  
<td>

Matthias et al., JGR 2004

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

_**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.
During ACTRIS-2, protocols and quality check procedures will be further
optimized, in particular for new products, in NA2 and data QC tools will be
developed in NA2 in collaboration with the data centre, checking the data
optical properties consistency and through the comparison with climatological
data. The SCC and all QC tools will be available to all potential users of
ACTRIS data, both internal and external.

##  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 all 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.

The cooperation of ACTRIS with EUDAT, has already started and will proceed
through ENVRI  PLUS  , providing a further instrument for discovering the
ACTRIS data sets.

###  Aerosol and trace gas near-surface data repository

The ACTRIS data repository for all aerosol and trace gas near-surface 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 (every 2 years) 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.

###  Cloud profile data repository

The ACTRIS data repository for all cloud profile data is  _http://www.cloud-
net.org_ .  The cloud profile database is currently hosted, maintained and
operated by the University of Reading, but is in transition to 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 secondary data and combined data products

ACTRIS secondary data 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 near-surface 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 _University of Lille_ , Villeneuve
d'Ascq, France, and the cloud profile data at _Reading University_ , Reading,
UK. There will be a transfer of the installation from Reading University to
FMI (Finnish Meteorological Institute) by May 2016.

##  Aerosol and trace gas near-surface 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 all 3 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 neighbor 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. Currently, a long-
term strategy for providing access to all ACTRIS data and other related
services are explored through the establishment of ACTRIS as a RI. For this
reason, ACTRIS is applying a position on the next ESFRI (European Strategy
Forum on Research Infrastructures) roadmap for Research Infrastructures.

##  Aerosol profiles

The storage infrastructure is composed by two servers and a 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 an internal 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 SAN.

The current size of the PostgresSQL EARLINET database is about 1GB. The total
amount of data submitted (NetCDF EARLINET files) is about 900MB. 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 Single Calculus Chain for the data submission, the inclusion
into the ACTRIS aerosol profiles database of new products (pre-processed 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 EARLINET database is 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. Further developments in terms of specific
services will be developed in ACTRIS 2 as aerosol profiles quality check tools
and processing through the SCC. Long term strategy for providing access to
data and other related services is explored through the establishment of
ACTRIS as a RI and for this reason ACTRIS is applying a position on the next
ESFRI (European Strategy Forum on Research Infrastructures) roadmap for
Research Infrastructures.

##  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
filesystems 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 transfer of the database to FMI will ensure the 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
centres run by scientists with expertise in the relevant field. This ensures
not only proper curation of the data, which makes the data usable by both,
experts and non-experts, 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 prerequisite, 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 an 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>

**Near-surface 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 near-surface 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**

**Variable name Recommended methodology**

</th>  
<th>

**Validated data**

</th>  
<th>

**NRT**

**Approx. time resolution**

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

**Column and profile aerosol particle variables (remote particle observations
from ground)**

</td>  
<td>

</td>  
<td>

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

Aerosol backscatter coefficient profile

</td>  
<td>

Backscatter lidar / 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>

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>

Multiwavelength backscatter lidar / 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>

Backscatter lidar / 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>

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>

Backscatter lidar / 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> </table>  
<table>  
<tr>  
<th>

**ACTRIS cloud variables**

**Variable _Recommended methodology_ **

</th>  
<th>

**Validated**

**_data NRT_ **

</th>  
<th>

**Approx. time /height resolution**

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

**Column and profile cloud variables (remote observations from ground)**

</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>

**Near-surface cloud 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 propane

2-methylpropane n-butane

</td>  
<td>

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

</td>  
<td>

**Alkenes**

</td>  
<td>

ethene

</td>  
<td>

**Alkynes**

</td>  
<td>

ethyne

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

propene

</td>  
<td>

proypne

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

trans-2-butene

</td>  
<td>

1-butyne

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

1-butene

</td>  
<td>

</td>  
<td>

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

2-2-dimethylpropane 2-methylbutane n-pentane cyclopentane methyl-cyclopentane

</td>  
<td>

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

</td>  
<td>

2-methylpropene

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

cis-2-butene

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

1-3-butadiene

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

3-methyl-1-butene

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

2-methyl-2-butene

</td>  
<td>

</td>  
<td>

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

2-2-dimethylbutane

2-3-dimethylbutane

2-methylpentane 3-methylpentane cyclohexane n-hexane methyl-cyclohexane

</td>  
<td>

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

</td>  
<td>

trans-2-pentene

</td>  
<td>

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

cyclopentene

</td>  
<td>

</td>  
<td>

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

1-pentene

</td>  
<td>

</td>  
<td>

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

cis-2-pentene

</td>  
<td>

</td>  
<td>

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

1-hexene

</td>  
<td>

</td>  
<td>

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

</td>  
<td>

isoprene

</td>  
<td>

</td>  
<td>

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

</td>  
<td>

</td>  
<td>

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

2-2-3-trimethylbutane

2-3-dimethylpentane

2-2-dimethylpentane

  2. 4-dimethylpentane 

  

  3. 3-dimethylpentane 

  

  

</td>  
<td>

</td>  
<td>

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

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

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

</td>  
<td>

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