TNA2: Access to PAL

WP Leader: Martial Haeffelin


Name of the infrastructure: SIRTA Atmospheric Observatory (PAL)
Location (town, country): Palaiseau, France
Web site address:
Legal name of organisation operating the infrastructure: Centre National de la Recherche Scientifique (CNRS)
Location of organisation (town, country): Paris, France
Annual operating costs (excl. investment costs) of the infrastructure (€): 380.555

Description of the infrastructure:
SIRTA is a French national atmospheric observatory dedicated to research on cloud and aerosol physical and chemical processes. SIRTA was established ten years ago by the Institut Pierre Simon Laplace (IPSL), a large research institute in environmental and climate sciences of the Paris metropolitan area (800 researchers and technical staff). The observatory is continuously supported by CNRS-INSU, Ecole Polytechnique, CNES (French Space Agency), and Météo-France, and operated by permanent staff of 2 scientists and 6 engineers.

SIRTA is located in a semi-urban environment, 25 km south of the Paris city center (48.7N, 2.2E). It is predominantly exposed to westerly winds that advect clean maritime air, alternating regularly with north-easterlies advecting a large range of continental air masses. SIRTA is ideally located to study both local/regional-scale processes typical to the urban-rural transition (e.g. formation mechanisms of gaseous and particulate pollution, effects of aerosols on fog and shallow cumulus) under high-pressure situations and larger-scale cloud-aerosol processes associated with baroclinic fronts.

The SIRTA observatory gathers an ensemble of state-of-the-art active and passive remote sensing instruments deployed by several research laboratories since 2002 for cloud and aerosol research. Instruments dedicated to permanent routine observations at SIRTA are a 355-nm backscatter and depolarization lidar, a 95 GHz FMCW radar, a wind profiling Sodar, a BSRN surface radiation station, an AERONET sunphotometer, a GPS receiver, a 14-channel microwave radiometer, sonic anemometers and weather sensors for surface meteorology, and 00 and 12UT radiosonde profiles (Météo-France).

A new research area on aerosol chemical composition and properties is open to users, based on CNRS-LSCE experience in long-term gas/aerosol observations (GAW activities) and the recent EU FP6 MEGAPOLI field experiment conducted in Paris by CNRS-LISA and LSCE. Long-term aerosol monitoring scheduled to start at SIRTA in 2010 include real-time chemical measurements of fine aerosols and other relevant parameters (absorption, light scattering, number size distribution, and possibly CCN). O3 and CO in-situ measurements will be implemented at SIRTA in 2010, if national funding is confirmed. In a second stage (also depending on national funding), in-situ VOC measurements (by GC-FID or by PTR-MS) will also be deployed.

The observatory provides access (1) to a radiation platform with 360-deg unobstructed view, a large observing field and platform for remote sensing and in-situ instruments, and two 30-m masts located 1km apart to study local scale dynamics and (2) to long time series of data, and data analysis software. Because of its proximity to a large research community, the observatory can also organize access to additional instruments (e.g. U.V. 266/289/316nm DIAL Lidar for Ozone profiling; UHF and X-band radars and doppler lidar for turbulence and wind profiling). SIRTA operates in a regional context of operational observing networks providing both long-term records and spatially distributed observations in the Paris region (e.g. 30 surface weather stations by Météo-France, 10 GPS stations by IGN, 55 air quality stations by AirParif).

The services at SIRTA include Radar and Lidar observations at SIRTA which were developed in the framework of EU-FP5-CloudNet and EU-FP5-FP6-EARLINET projects. Tropospheric profiling observations of clouds and aerosols at SIRTA have been used in scientific studies (nearly 50 publications) to study processes controlling cloud and fog life cycle, to study aerosol transport, to evaluate NWP, CTM and GCM models, and to validate satellite measurements (e.g. Calipso, CloudSat). Cloud-aerosol interactions are under study in the framework of ParisFog, a national project to investigate cloud-aerosol interactions in continental fog.

Results from the EU-FP7-MEGAPOLI programme (field experiments in July 09 – Jan. 2010) have shown that SIRTA benefits most of the time from atmospheric background conditions (upwind of Paris urban area) and can be considered as a site representative of Northern France (upwind of the Rhine-Ruhr hot spot). Time-limited pollution plumes from Paris urban area can offer the extra opportunity to investigate processed urban pollution emitted from this major EU megacity (12 millions of inhabitants, 20% of the French population).

The SIRTA observatory is designed to provide access to the data and to the facility. Access has been provided to scientists, researchers and engineers since the late 1990’s for the following applications:

(1) Instrument inter-comparison campaigns (e.g. Earlinet Lidar Intercomparison 2000; CloudNet Radar intercomparison 2005). (2) Scientific field campaigns (e.g. ParisFog national experiment (Oct. 2006 – Mar 2007) to study key processes involved in the life cycle of fog: over 300 user-days. MEGAPOLI international field experiment (Jul 2009 and Feb 2010) to study formation mechanisms of particle pollution: 300 user-days in 2009 and in 2010). (3) Data access: Each year about 10000 requests are made to the SIRTA database. About 150000 files or 100 Go of data are transferred by users. Users are about 75% of national origin and 25% from international research institutes. (4) University experimental work: Several hundred students access the SIRTA observatory each year to participate in experimental work as part of their university curriculum. 10 students participated in an experimental workshop at SIRTA through a Marie-Curie FP6 action. (5) Visiting scientist program: Visiting scientists have been funded to come to SIRTA for periods ranging between 3 and 6 months. Visitors that use the SIRTA facility benefit from the proximity of the large CNRS-IPSL research community in Paris.

Description of work

Modality of access under this project:
Access to the SIRTA observatory infrastructure will take place at Ecole Polytechnique in Palaiseau,
France. Access can be requested for 1-3 months field campaigns, or short-term (1-3 weeks) instrument intercomparisons, or – in exceptional cases – longer-term monitoring. Once a user is approved and interference with other projects has been cleared, users will have access to the different observing platforms to deploy their instruments, to the necessary electrical power to operate them, and to a data network for internet access. Users can either deploy equipment in their own containers or request to be hosted in a SIRTA container (depending on space availability). Once users have read, understood and signed the SIRTA safety regulation chart they will be able to freely access the SIRTA facility.

Support offered under this project:
Once an access has been validated, SIRTA will provide technical, scientific and administrative support. Prior to any access, a user, or user group will interact with the team operating SIRTA to specify precise access needs and constraints (e.g. electrical, network, safety, and security constraints related to instrument deployments) so that they can be cleared ahead of the access period. The SIRTA team will provide technical assistance to users and their group for deployment of equipment (connections, remote access, storage, safety) upon their arrival at the SIRTA observatory. Users deploying equipment are expected to operate their own equipment and must
take full responsibility for it. The goal is minimize deployment time and downtime during the access period, to maximize user benefit.
SIRTA scientific staff will assist users with access to routine SIRTA data. A local scientific staff will help promote the user activity to facilitate contact with the CNRS-IPSL scientific community in the Palaiseau-Saclay area (LMD/LSCE – Ecole Polytechnique and CEA), in Guyancourt (LATMOS – Université de Versailles Saint Quentin) and in Jussieu (LMD/LATMOS – Université Pierre et Marie Curie). LATMOS, LMD and LSCE are research laboratories that are world recognized for their excellence in atmospheric observation and modelling. Users will be given an opportunity to present their project to the SIRTA scientific board that includes members from ten research laboratories in France.
Transport support will be provided through the CNRS Ulisse transportation service with assistance from the SIRTA staff. SIRTA will also provide assistance for safety regulation issues if they are declared well in advance (e.g. specific radar frequencies, or radioactive sources). For accommodation, we will direct users to the “Science Welcome” association ( - in which Ecole Polytechnique is a founding member) that assist people coming for professional purposes.
As an example, this procedure was implemented in 2009 to provide access to over 300 research working days in the framework of the EU-FP6-MEGAPOLI project.

Outreach of new users:
The SIRTA observatory is presented every year in several international conferences, either through scientific studies or specifically as a research facility. Similarly the SIRTA facility is referred to in a dozen peer-reviewed articles every year. Since 2005, the SIRTA web site contains a page dedicated to infrastructure access that provides guidelines and a form for deployment at SIRTA. A modernized SIRTA website should be available in fall 2010, that will significantly improve referencing. The SIRTA observatory maintains a high profile internationally by participating in international networks such as WMO-BSRN, NASA-AERONET, EU-FP5 and FP6 networks (e.g. EARLINET), and in EU-COST actions (e.g. ES0702 EG-CLIMET).
In addition, we will promote the new opportunity for TNA access to the SIRTA observatory multiple websites and through dedicated flyers to be distributed during key scientific conferences. The combination of state-of-the-art instrument development and operation, and top-level meso-scale and climate modelling research make the IPSL observatory a very attractive place in Europe to conduct experiments.

Review procedure under this project:
The selection of users will be performed by a single TNA selection panel and is described under the general ACTRIS procedure in section 2.1.6.

Unit of Access:
One unit of access corresponds to 1 full research person-working day (rwd) by a user accessing the infrastructure (the minimum acceptable access is half a day). The access includes the use of the general infrastructure, on-site logistic support by the infrastructure staff, as well as technical and scientific support related to the use of the facility and data analysis. A confirmation of visit indicating the total quantity of access per user, countersigned by the access provider, is provided after each access.

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