SIRTA-ReOBS is a project whose goal is to synthetize, analyze, homogeneize, all SIRTA observations hourly averaged in a single NetCDF file.
It has been developped in order to study regional climate variability, for the particular case of Paris area.

Actually, when interested in the regional climate scales that involve both the influence of large-scale atmospheric circulation and local processes, it is necessary to use a dataset suitable for these scales. But the exercise is complex because it involves all the system parameters and all spatial and temporal scales. Also the small magnitude of the signals that we are looking for, and connections between processes at local scales and anomalies at climate scale, add to this complexity. It is therefore necessary to use a dataset dedicated to these climate issues: multi-year, with good time resolution (hourly), multi-parameters without calibration problem.

To make its data easily usable, the SIRTA [Haeffelin et al., 2005] provides an important work on their homogenization, quality control, averaging... The goal of SIRTA-ReOBS project is to write in a single netcdf file all variables hourly averaged from 2003 to now, their description, quality control indices, their spatial and temporal variability.

SIRTA-ReOBS is relevant to answer the question of the variability observed in the Paris region at the decadal scale because:

  • The oldest observations date back to 2003 and therefore have a strong statistical value in addition to the multi-annual coverage
  • The time resolution also allows to address the daily cycle scale
  • Multi-parameter approach allows rising to the level of processes
  • The coupling of in situ, passive, and active remote sensing measurement, provides the most possible resolved atmospheric column at all time scales mentioned above

This approach is consistent with different international initiatives such as the COPERNICUS Climate Change Service (C3S) European project. It is also discussed in the framework of ACTRIS European project, and it has been identified as recommendation #12 by the WCRP climate symposium 2014.

SIRTA-ReOBS scientific manager: Marjolaine Chiriaco, LATMOS/UVSQ


SIRTA-ReOBS has been supported and funded by the Ecole Polytechnique, EUCLIPSE European project, IPSL, LABEX IPSL.


SIRTA-ReOBS poster


Chiriaco M., Dupont J.-C., Bastin S., Badosa J., López J., Haeffelin M., Chepfer H., Guzman R., 2018: ReOBS: a new approach to synthesize long-term multi-variable dataset and application to the SIRTA supersite. Earth System Science Data, Copernicus Publications, 10 (2), pp.919 - 940.

Chiriaco M., S. Bastin, P. Yiou, M. Haeffelin, J.-C. Dupont, L. Klenov, M. Stéfanon, 2014: European heat-wave in July 2006 : observations and modelling showing how local processes amplify conducive large-scale conditions. Geophys. Res. Let., 41 issue 15, 5644 – 5652.

Cheruy F., J. C. Dupont, A. Campoy, A. Ducharne, F. Hourdin, M. Haeffelin, M. Chiriaco, 2013: Combined influence of atmospheric physics and soil hydrology on the realism of the LMDz model compared to SIRTA measurements. Clim. Dyn., DOI 10.1007/s00382-012-1469-y.

Haeffelin, M., L. Barthès, O. Bock, C. Boitel, S. Bony, D. Bouniol, H. Chepfer, M. Chiriaco, J. Cuesta, J. Delanoë, P. Drobinski, J-L. Dufresne, C. Flamant, M. Grall, A. Hodzic, F. Hourdin, F. Lapouge, Y. Lemaître, A. Mathieu, Y. Morille, C. Naud, V. Noël, B. O'Hirok, J. Pelon, C. Pietras, A. Protat, B. Romand, G. Scialom, R. Vautard, 2005: SIRTA, a ground-based atmospheric observatory for cloud and aerosol research." Annales Geophysic., 23, pp 253-275.

Time dimensions of the NetCDF file

Dimension name Description Period of obs.
time_RS Time for radiosounding products 2003-2017
time_mld Time for mixing layer depth products 2008-2014
time_lna Time for lidar profiles products 2003-2015
time_moleculaire Index of time dimension for molecular profiles 2003-2015
time Main time 2003-2016

Lidar profiles dimensions

Dimension name Description
binSR SR (scattering ratio) classification bins
binSTRAT STRAT classification bins
range_lna Altitude range for lidar histograms

Trappes radiosounding profiles dimensions

Dimension name Description
level level of radiosounding profiles
binSTRAT STRAT classification bins
range_lna Altitude range for lidar histograms

Classical meteorological measurements

Variable Description Period of obs. Reference
tas_sirta 2-m air temperature, K 2003-2016 --
hurs_sirta 2-m relative humidity, % 2003-2016 --
huss_sirta 2-m specific humidity , kg/kg 2003-2016 --
psl_sirta Sea-level pressure, Pa 2003-2016 --
sfcWind_sirta 2-m wind speed, m/s 2003-2016 --
vas_sirta 2-m northward wind, degree 2003-2016 --
uas_sirta 2-m eastward wind, degree 2003-2016 --
visi_sirta Visibility, m 2012-2016 --
pr_sirta Precipitation at surface, kg/m 2/s 2003-2014 --
tas_trps Trappes air temperature, K 2005-2014 --
hurs_trps Trappes relative humidity, % 2005-2014 --
psl_trps Trappes Sea-level pressure, hPa 2005-2014 --
ff_trps Trappes wind speed, m/s 2005-2014 --
vas_trps Trappes northward wind, degree 2005-2014 --
uas_trps Trappes eastward wind, degree 2005-2014 --
visi_trps Trappes Visibility, m 2005-2014 --
pr_trps Trappes Precipitation at surface, mm/hr 2003-2014 --
hurs_regional Regional relative humidity, % 2004-2014 --
pr_regional Regional precipitation rate, mm/h 2004-2014 --
psl_regional Regional surface air pressure, hpa 2004-2014 --
uas_regional Regional eastward component of wind, degree 2004-2014 --
vas_regional Regional northward component of wind, degree 2004-2014 --
ws_regional Regional wind speed, m/s 2004-2014 --
tas_regional Regional air temperature, K 2004-2014 --

Advanced measurements

Variable Description Period of obs. Reference
rlds Surface downwelling longwave radiation, W/m 2 2003-2016 --
rlus Surface downwelling shortwave radiation, W/m 2 2007-2016 --
rsds Surface downwelling shortwave radiation, W/m 2 2003-2016 --
rsus Surface upwelling shortwave radiation, W/m 2 2007-2016 --
hfs(l)s Surface upward sensible (latent) heat flux, W/m 2 2006-2014 --
saa solar_azimuth_angle, degree 2003-2015 --
sza solar_zenith_angle, degree 2003-2016 --
stx 1 Soil temperature x cm bellow ground level, K 2007-2015 --
Smx 1 Soil moisture x cm bellow ground level, g/cm 3 2007-2012 --
channel_x_mean 2 Mean brightness temperature from MSG at x µm, K 2005-2010 --

Parameters retrieved from observations

Variable Description Period of obs. Reference
cf_nfov_als Lidar cloud fraction 2008-2012 Morille et al. 2007
cf_nfov_lna Lidar cloud fraction 2003-2008 Morille et al. 2007
rsdscs Surface downwelling shortwave radiation for clear sky, W/m 2 2003-2015 Long et al. 2006
rldscs Surface downwelling longwave radiation for clear sky, W/m 2 2003-2015 Long et al. 2006
tot_cld_tsi Cloud fraction from sky imager 2009-2014 --
cflw Cloud fraction from longwave radiation 2003-2014 Long et al. 2006
cfsw Cloud fraction from shortwave radiation 2003-2014 Long et al. 2006
cbhx 3 Lidar cloud base heigh, m 2008-2013 Morille et al. 2007
aot_x 4 Aerosol optical thickness at x nm 2008-2014 Aeronet
water Clear sky integrated watr vapor, kg/m 2 2008-2014 Aeronet
angstrom_x-y 5 Angstrom exponent between x and y nm, nm 2008-2014 Aeronet
cld_frac Percentage cloudy pixels over 15x15 pixels 2005-2010 Roebeling et al. 2006
clwp_mean Mean cloud liquid water path over 15x15 pixels, g/m 2 2005-2010 Roebeling et al. 2006
ctt_mean Mean cloud top temperature over 15x15 pixels, K 2005-2010 Roebeling et al. 2006
reff_mean Mean cloud effective radius over 15x15 pixels, mm 2005-2010 Roebeling et al. 2006
tau_mean Mean cloud optical thickness over 15x15 pixels, g/m 2 2005-2010 Roebeling et al. 2006
lwp Liquid_water_path, g/m 2 2012-2016 --
mld Mixing_layer_depth, m 2008-2014 --
iwv Integrated water vapor, Kg/m 2 2006-2016 --

Vertical lidar measurements

Variable Description Period of obs. Reference
SRhisto Lidar scaterring ratio vertical histograms 2003-2015 --
STARThisto Lidar STRAT classification vertical histograms 2003-2015 Morille et al. 2007
pr2_mol Lidar molecular profile 2003-2015 --
norm_height Altitude of normalisation of lidar profiles, m 2003-2015 --

1x is 5 cm, 10 cm, 20 cm, 30 cm, 50 cm.

2x is 12, 0.6, 0.8, 1.6, 3.8, 10.8 µm.

3x is first layer (1), second layer (2), third layer (3)

4x is 1020, 870, 675, 500, 440, 380, 340 nm.

5x and y are the interval between 4 values.

Parameters currently included in SIRTA-ReOBS. First block is for classical meteorological measurements, second block is for more advanced measurements, third block is for parameters retrieved from observations, fourth block is for vertical lidar measurements.

SIRTA-ReOBS content at 2015-06; about 50 parameters, 2003 – 2015 for the oldest data.

Scientific manager:

Scientific support:

Technical support:

SIRTA-ReOBS is free access

If you publish with SIRTA-ReOBS, please contact us. Depending on the type of use, we will indicate you wich one of these solutions is adapted:

  • simple use that do not require our expertise: mention SIRTA-ReOBS publications, and acknowledgements.
  • intensive use that require our expertise: one of SIRTA-ReOBS scientist is associated to your publication and brings its expertise: Marjolaine Chiriaco, Jean-Charles Dupont, Jordi Badosa, or Martial Haeffelin. See Contact tab.
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sirta-ReOBS file 200301-201712 Download

sirta-ReOBS file without lidar profiles 200301-201712 Download

version V1-2-1

New variables added :

  • Trappes radiosounding profiles measurements ("_RS" sufix)

version V1-1-1

New variables added :

  • Trappes classical meteorological measurements ("trps_" prefix)
  • Integrated water vapor calculate by GPS system (iwv)
  • Regional meteorolgy ("_regional" suffix)

Variables modified :

  • Variable cf_nfov splited in two variables :
  • Variable name Description Period
    cf_nfov_als Cloud fraction from als(Aerosol Lidar System) at 355 nm 2008-2012
    cf_nfov_lna Cloud fraction from lna(Lidar Nouages Aerosols) at 532 and 1064 nm 2003-2008

Renamed variables :

Old variable name New variable name
mu_fclw std_fclw
mu_cfsw std_cfsw
mu_hfls std_hfls
mu_hfss std_hfss
mu_hurs std_hurs
mu_huss std_huss
mu_ps std_ps
mu_psl std_psl
mu_rlds std_rlds
mu_rlus std_rlus
mu_rsdscs std_rsdscs
mu_rsus std_rsus
mu_sfcWind std_sfcWind
mu_sm5 std_sm5
mu_sm10 std_sm10
mu_sm20 std_sm20
mu_sm50 std_sm50
mu_st5 std_st5
mu_st10 std_st10
mu_st20 std_st20
mu_st50 std_st50
mu_solar_zenith_angle std_solar_zenith_angle
mu_tas std_tas
mu_tot_cld_tsi std_tot_cld_tsi
mu_uas std_uas
mu_vas std_vas
mu_water std_water
mu_cflw std_cflw
mu_rldscs std_rldscs
d_lwp std_lwp
d_prp std_prp
d_reff std_reff
d_sds std_sds
d_tau std_tau
d_visi std_visi
340-440angstrom angstrom_340-440
380-500angstrom angstrom_380-500
440-675angstrom angstrom_440-675
440-870angstrom angstrom_440-870
500-870angstrom angstrom_500-870
sfcWind sfcWind_sirta
tas tas_sirta
hurs hurs_sirta
huss huss_sirta
pr pr_sirta
ps ps_sirta
psl psl_sirta
uas uas_sirta
vas vas_sirta
visi visi_sirta

Deleted variables :

  • Spatial Uncertainty variables
Old variable name