scholarly journals Results from the validation campaign of the ozone radiometer GROMOS-C at the NDACC station of La Réunion Island

2016 ◽  
Author(s):  
Susana Fernandez ◽  
Rolf Rüfenacht ◽  
Niklaus Kämpfer ◽  
Thierry Portafaix ◽  
Françoise Posny ◽  
...  
Keyword(s):  
Middle Atmosphere ◽  
Microwave Radiometer ◽  
Estimation Method ◽  
Emission Spectra ◽  
Optimal Estimation ◽  
Reunion Island ◽  
La Réunion ◽  
North East ◽  
Réunion Island ◽  
La Réunion Island

Abstract. Abstract. Ozone is a species of primary interest as it performs a key role in the middle atmosphere and its monitoring is thus necessary. At the Institute of Applied Physics of the University of Bern, Switzerland, we built a new ground based microwave radiometer, GROMOS-C (GRound based Ozone MOnitoring System for Campaigns). It has a compact design and can be operated at remote places with very little maintenance requirements, being therefore suitable for remote deployments. It has been conceived to measure the vertical distribution of ozone in the middle atmosphere, by observing pressure broadened emission spectra at a frequency of 110.836 GHz. In addition, meridional and zonal wind profiles can be retrieved, based on the Doppler shift of the ozone line measured in the 4 directions of observation (North-East-South-West). In June 2014 the radiometer was installed in the Maïdo observatory, on La Réunion Island (21.2° S, 55.5° E). High resolution ozone spectra were continuously recorded during 7 months. Vertical profiles of ozone have been retrieved through an optimal estimation inversion process, using the Atmospheric Radiative Transfer Simulator ARTS2 as the forward model. The best estimate of the vertical profile is done by means of the optimal estimation method. The validation is performed against ozone profiles from the Microwave Limb Sounder (MLS) on the Aura satellite, the ozone lidar located in the observatory and with ozone profiles from weekly radiosondes. Zonal and meridional winds retrieved from GROMOS-C data are validated against another wind radiometer located in situ, WIRA. In addition, we compare both ozone and winds with ECMWF model data. Results show that GROMOS-C provides reliable ozone profiles between 30 to 0.02 hPa. The comparison with lidar shows a very good agreement at all levels. The accordance with MLS is within less than 10 % for pressure levels between 25 and 0.2 hPa.

scholarly journals Results from the validation campaign of the ozone radiometer GROMOS-C at the NDACC station of Réunion island

2016 ◽  
Vol 16 (12) ◽  
pp. 7531-7543 ◽  
Author(s):  
Susana Fernandez ◽  
Rolf Rüfenacht ◽  
Niklaus Kämpfer ◽  
Thierry Portafaix ◽  
Françoise Posny ◽  
...  
Keyword(s):  
Middle Atmosphere ◽  
Microwave Radiometer ◽  
Optimal Estimation ◽  
Reunion Island ◽  
Model Data ◽  
Data Set ◽  
North East ◽  
Réunion Island ◽  
Wind Profiles ◽  
Good Agreement

Abstract. Ozone performs a key role in the middle atmosphere and its monitoring is thus necessary.At the Institute of Applied Physics of the University of Bern, Switzerland, we built a new ground-based microwave radiometer, GROMOS-C (GRound based Ozone MOnitoring System for Campaigns). It has a compact design and can be operated remotely with very little maintenance requirements, being therefore suitable for remote deployments. It has been conceived to measure the vertical distribution of ozone in the middle atmosphere, by observing pressure-broadened emission spectra at a frequency of 110.836 GHz. In addition, meridional and zonal wind profiles can be retrieved, based on the Doppler shift of the ozone line measured in the four directions of observation (north, east, south and west).In June 2014 the radiometer was installed at the Maïdo observatory, on Réunion island (21.2° S, 55.5° E). High-resolution ozone spectra were recorded continuously over 7 months. Vertical profiles of ozone have been retrieved through an optimal estimation inversion process, using the Atmospheric Radiative Transfer Simulator ARTS2 as the forward model. The validation is performed against ozone profiles from the Microwave Limb Sounder (MLS) on the Aura satellite, the ozone lidar located at the observatory and with ozone profiles from weekly radiosondes. Zonal and meridional winds retrieved from GROMOS-C data are validated against another wind radiometer located in situ, WIRA. In addition, we compare both ozone and winds with ECMWF (European Centre for Medium-Range Weather Forecasts) model data. Results show that GROMOS-C provides reliable ozone profiles between 30 and 0.02 hPa. The comparison with lidar profiles shows a very good agreement at all levels. The accordance with the MLS data set is within 5 % for pressure levels between 25 and 0.2 hPa. GROMOS-C's wind profiles are in good agreement with the observations by WIRA and with the model data, differences are below 5 m s−1 for both.

scholarly journals Analysis of gravity waves in the tropical middle atmosphere over La Reunion Island (21°S, 55°E) with lidar using wavelet techniques

2000 ◽  
Vol 18 (4) ◽  
pp. 485-498 ◽  
Author(s):  
F. Chane-Ming ◽  
F. Molinaro ◽  
J. Leveau ◽  
P. Keckhut ◽  
A. Hauchecorne
Keyword(s):  
Middle Atmosphere ◽  
Phase Speed ◽  
Winter Period ◽  
Reunion Island ◽  
Austral Winter ◽  
La Réunion ◽  
Data Set ◽  
Réunion Island ◽  
Wavelet Techniques ◽  
La Réunion Island

Abstract. The capabilities of the continuous wavelet transform (CWT) and the multiresolution analysis (MRA) are presented in this work to measure vertical gravity wave characteristics. Wave properties are extracted from the first data set of Rayleigh lidar obtained between heights of 30 km and 60 km over La Reunion Island (21°S, 55°E) during the Austral winter in 1994 under subtropical conditions. The altitude-wavelength representations deduced from these methods provide information on the time and spatial evolution of the wave parameters of the observed dominant modes in vertical profiles such as the vertical wavelengths, the vertical phase speeds, the amplitudes of temperature perturbations and the distribution of wave energy. The spectra derived from measurements show the presence of localized quasi-monochromatic structures with vertical wavelengths <10 km. Three methods based on the wavelet techniques show evidence of a downward phase progression. A first climatology of the dominant modes observed during the Austral winter period reveals a dominant night activity of 2 or 3 quasi-monochromatic structures with vertical wavelengths between 1-2 km from the stratopause, 3-4 km and 6-10 km observed between heights of 30 km and 60 km. In addition, it reveals a dominant activity of modes with a vertical phase speed of -0.3 m/s and observed periods peaking at 3-4 h and 9 h. The characteristics of averaged vertical wavelengths appear to be similar to those observed during winter in the southern equatorial region and in the Northern Hemisphere at mid-latitudes.Key words: Meteorology and atmospheric dynamics (climatology; middle atmosphere dynamics; waves and tides)

Diurnal and seasonal variation of carbonaceous aerosols at a remote MBL site of La Réunion island

2001 ◽  
Vol 57 (2) ◽  
pp. 105-121 ◽  
Author(s):  
Chatrapatty Bhugwant ◽  
Miloud Bessafi ◽  
Emmanuel Rivière ◽  
Jean Leveau
Keyword(s):  
Seasonal Variation ◽  
Carbonaceous Aerosols ◽  
Reunion Island ◽  
La Réunion ◽  
Réunion Island ◽  
La Réunion Island
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