Observatory of Atmospheric Physics in Reunion

Measured parameters

OPAR hosts and operates 51 instruments, including 6 large passive and active remote sensing instruments.

Two Fourier Transform Infrared Spectrometers (FTIR) belonging to the Belgian Institute for Space Aeronomy (IASB) and four lidars developed in partnership with LATMOS measure partial columns (FTIR) and profiles (lidars) of physical parameters (wind and temperature) and chemical parameters (aerosols, water vapor, ozone and other infrared-absorbing trace gases such as carbon monoxide, hydrogen cyanide, ethane, acetylene, formaldehyde, methanol and formic acid).

The atmospheric layers surveyed range from the lower troposphere to the thermosphere, depending on the parameters considered. Since 2012, thanks to the participation of the Laboratoire de Météorologie Physique (LaMP), the Cyprus Institute and the Laboratoire des Sciences du Climat et de l’Environnement (LSCE), OPAR has been equipped with an extensive array of in-situ observation resources for determining the chemical gas composition, water vapor isotopy and dimensional, optical and chemical properties of aerosols.

A set of spectroradiometric instruments enables us to observe the different components of the solar spectrum (from infrared to ultraviolet), and are key elements in studies to monitor the integrated quantity of ozone and aerosols, their radiative impact on the ground, and the influence of UV on health. On a tropical island where convective and cyclonic activity can be very intense, clouds and hydrometeors are studied using Doppler radar and disdrometers. Finally, balloon-borne probes are released on a regular basis or during campaigns to document the precise vertical distribution of ozone, water vapour, temperature and aerosols from the ground to the stratosphere.

Unique in the Southern Hemisphere and one of the most comprehensive in the world, this array of instruments provides high-quality data for satellite calibration and validation, climate monitoring in the Southern Hemisphere, the study of the physical and chemical processes involved, and the improvement of climate forecasting models.

OPAR, and in particular the Maïdo observatory, is also designed to host scientific and technical teams for the installation of instruments over long periods, as well as for the conduct of intensive campaigns on this unique tropical site. Since the beginning of 2013, 32 campaigns have been carried out in collaboration with 19 French and foreign laboratories.

Non-exhaustive list of OPAR instruments with their range, measured parameters and installation site.

CIMEL solar photometerSaint-DenisOptical and physical properties of aerosolsIntegrated column
Bentham spectroradiometerSaint-DenisUV solar spectrumIntegrated column
SAOZSaint-DenisQuantity of O3, NO2Integrated column
FTIRSaint-DenisQuantity of greenhouse gases
(partial columns)
Troposphere and stratosphere
Mobile Aerosol LidarSaint-DenisAerosol backscatter and extinction profilesTroposphere
BASTA RadarSaint-DenisCloud properties
(radar reflectivity, Doppler velocity)
Disdrometer 2DVDSaint-DenisDrop size distributionIn situ
PICARRO 3GSaint-DenisConcentration of greenhouse gases (CO2, CH4, H2O)In situ
Radiosurveys (MODEM+ECC)GillotProfiles of relative humidity, temperature, wind, O3 concentrationTroposphere and stratosphere
PICARRO 4GMaïdoConcentration of greenhouse gases
(CO, CO2, CH4, H2O)
In situ
SO2 analyzerMaïdoSO2 concentration
(UV fluorescence)
In situ
O3 analyzerMaïdoO3 concentration (UV absorption)In situ
AethalometerMaïdoConcentration of optically absorbing particles
("soot carbon")
In situ
Chemical filtersMaïdoPM, ions (Cl, NO3, SO4, Na, K, Mg, Ca), organic tracersIn situ
Condensation Particle CounterMaïdoAerosol number concentrationIn situ
Differential Mobility Particle SizerMaïdoAerosol number concentration and size distribution (2.5-900nm)In situ
Optical Particle SizerMaïdoAerosol number concentration and size distribution
In situ
Cloud Condensation Nuclei CounterMaïdoNumber concentration of cloud condensation nucleiIn situ
PICARRO H2OMaïdoSpecific humidity and water vapor isotope ratioIn situ
Radiometer j(NO2)MaïdoNO2 photolysis frequencyIn situ
NOy spectrometerMaïdoNOy concentrationIn situ
FTIRMaïdoQuantity of greenhouse gases
(partial columns)
Troposphere and stratosphere
Stratospheric O3 Lidar MaïdoO3 concentration profilesStratosphere
Tropospheric O3 Lidar MaïdoO3 concentration profilesTroposphere
Tropospheric O3 Lidar MaïdoAerosol backscatter and extinction profilesTroposphere et stratosphere
LIDAR1200MaïdoTemperature profilesTroposphere-lower stratosphere
LIDAR1200MaïdoAerosol backscatter and extinction profilesStratosphere-thermosphere
LIDAR1200MaïdoAerosol backscatter and extinction profilesTroposphere and stratosphere
Wind LidarMaïdoHorizontal wind speed profiles Troposphere and stratosphere