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Papers by Alain Hauchecorne
EPJ Web of Conferences, 2018
A unique Rayleigh-Mie Doppler lidar capable of wind measurements in the 5-50 km altitude range is... more A unique Rayleigh-Mie Doppler lidar capable of wind measurements in the 5-50 km altitude range is operated routinely at La Reunion island (21° S, 55° E) since 2015. We evaluate instrument’s capacities in capturing fine structures in stratospheric wind profiles and their temporal and spatial variability through comparison with collocated radiosoundings and ECMWF analysis. Perturbations in the wind velocity are used to retrieve gravity wave frequency spectrum.
Atmospheric Chemistry and Physics, 2018
The Review of Laser Engineering, 1995
EPJ Web of Conferences, 2018
A unique Rayleigh-Mie Doppler lidar capable of wind measurements in the 5-50 km altitude range is... more A unique Rayleigh-Mie Doppler lidar capable of wind measurements in the 5-50 km altitude range is operated routinely at La Reunion island (21° S, 55° E) since 2015. We evaluate instrument’s capacities in capturing fine structures in stratospheric wind profiles and their temporal and spatial variability through comparison with collocated radiosoundings and ECMWF analysis. Perturbations in the wind velocity are used to retrieve gravity wave frequency spectrum.
Annales Geophysicae, 2000
Atmospheric Chemistry and Physics, 2018
Atmospheric Measurement Techniques, 2019
Journal of Geophysical Research: Atmospheres, 2015
Atmospheric Chemistry and Physics Discussions, 2010
Atmospheric Measurement Techniques Discussions, 2014
Atmospheric Measurement Techniques, 2013
Earth System Science Data, 2013
Journal of Geophysical Research: Atmospheres, 2006
The Global Ozone Monitoring by Occultation of Stars (GOMOS) instrument on board the European Spac... more The Global Ozone Monitoring by Occultation of Stars (GOMOS) instrument on board the European Space Agency's Envisat satellite measures ozone and a few other trace gases using the stellar occultation method. Global coverage, good vertical resolution and the self‐calibrating measurement method make GOMOS observations a promising data set for building various climatologies. In this paper we present the nighttime stratospheric ozone distribution measured by GOMOS in 2003. We show monthly latitudinal distributions of the ozone number density and mixing ratio profiles, as well as the seasonal variations of profiles at several latitudes. The stratospheric profiles are compared with the Fortuin‐Kelder daytime ozone climatology. Large differences are found in polar areas and they can be shown to be correlated with large increases of NO2. In the upper stratosphere, ozone values from GOMOS are systematically larger than in the Fortuin‐Kelder climatology, which can be explained by the diurn...
Journal of Geophysical Research: Atmospheres, 2007
Nighttime remote‐sensing balloon observations conducted by the SALOMON instrument in the arctic p... more Nighttime remote‐sensing balloon observations conducted by the SALOMON instrument in the arctic polar vortex in January 2006 reveal high amounts of stratospheric NO2 in the lower stratosphere similarly to previously published profiles. NO2 concentration enhancements are also present in the vertical profiles observed by the GOMOS instrument on board the Envisat satellite and obtained coincidently to the balloon measurements. Such quantities are not present in in situ observations obtained by the SPIRALE instrument in similar geophysical conditions. While OClO amounts are acceptably reproduced by Chemistry Transport Model (CTM) calculations, NO2 simulated values are well below the observed quantities. The examination of the slant column densities of NO2 obtained at float altitude highlights unexpected strong enhancements with respect to the elevation angle and displacement of the balloon. It is shown that these fluctuations result from NO2 spatial inhomogeneities located above the bal...
Journal of Geophysical Research: Atmospheres, 2010
This publication provides a detailed study of one cirrus cloud observed by lidar at the Observato... more This publication provides a detailed study of one cirrus cloud observed by lidar at the Observatory of Haute‐Provence (∼44°N) in January 2006 in the vicinity of the tropopause (12–14 km/∼136–190 hPa/328–355 K). The higher part of the air mass observed comes from the wet subtropics while the lower part comes from the midlatitudes. Both are advected by the Azores anticyclone, encounter cold temperatures (∼205 K) above the North Atlantic Ocean, and flow eastward along the anticyclonic flank of the polar jet stream. A simulation of this cloud by an isentropic model is tested to see if synoptic‐scale atmospheric structures could explain by itself the presence of such clouds. The developments made in the Modélisation Isentrope du transport Méso‐échelle de l'Ozone Stratosphérique par Advection (MIMOSA) model to take into account the three phases of water and their interactions allow reproduction of the occurrence of the cirrus and its temporal evolution. MIMOSA‐H2O reproduces the atmos...
Journal of Geophysical Research: Atmospheres, 2005
In September 2002 the Antarctic polar vortex split in two under the influence of a sudden warming... more In September 2002 the Antarctic polar vortex split in two under the influence of a sudden warming. During this event, the Odin satellite was able to measure both ozone (O3) and chlorine monoxide (ClO), a key constituent responsible for the so‐called “ozone hole”, together with nitrous oxide (N2O), a dynamical tracer, and nitric acid (HNO3) and nitrogen dioxide (NO2), tracers of denitrification. The submillimeter radiometer (SMR) microwave instrument and the Optical Spectrograph and Infrared Imager System (OSIRIS) UV‐visible light spectrometer (VIS) and IR instrument on board Odin have sounded the polar vortex during three different periods: before (19–20 September), during (24–25 September), and after (1–2 and 4–5 October) the vortex split. Odin observations coupled with the Reactive Processes Ruling the Ozone Budget in the Stratosphere (REPROBUS) chemical transport model at and above 500 K isentropic surfaces (heights above 18 km) reveal that on 19–20 September the Antarctic vortex...
Journal of Geophysical Research: Atmospheres, 2005
The Global Ozone Monitoring by Occultation of Stars (GOMOS) stellar occultation instrument on boa... more The Global Ozone Monitoring by Occultation of Stars (GOMOS) stellar occultation instrument on board the Envisat European satellite provides global coverage of ozone and other stratospheric species with good vertical resolution and a self‐calibrating method. In this paper we present the first simultaneous global distribution of stratospheric NO2 and NO3 from 1 year of nighttime GOMOS data in 2003. Most previous NO2 satellite observations have been made using the solar occultation technique. They are difficult to interpret due to the fast photochemical evolution of NO2 at sunrise and sunset. There are no published observations of NO3 from space because this constituent is rapidly photodissociated during daytime and is not observable by solar occultation. It is shown that the NO2 mixing ratio reaches a maximum around 40 km with values between 14 and 16 ppbv at low and middle latitudes. The global distribution of NO2 observed by GOMOS is very similar to the NO + NO2 Halogen Occultation ...
Journal of Geophysical Research: Atmospheres, 1996
EPJ Web of Conferences, 2018
A unique Rayleigh-Mie Doppler lidar capable of wind measurements in the 5-50 km altitude range is... more A unique Rayleigh-Mie Doppler lidar capable of wind measurements in the 5-50 km altitude range is operated routinely at La Reunion island (21° S, 55° E) since 2015. We evaluate instrument’s capacities in capturing fine structures in stratospheric wind profiles and their temporal and spatial variability through comparison with collocated radiosoundings and ECMWF analysis. Perturbations in the wind velocity are used to retrieve gravity wave frequency spectrum.
Atmospheric Chemistry and Physics, 2018
The Review of Laser Engineering, 1995
EPJ Web of Conferences, 2018
A unique Rayleigh-Mie Doppler lidar capable of wind measurements in the 5-50 km altitude range is... more A unique Rayleigh-Mie Doppler lidar capable of wind measurements in the 5-50 km altitude range is operated routinely at La Reunion island (21° S, 55° E) since 2015. We evaluate instrument’s capacities in capturing fine structures in stratospheric wind profiles and their temporal and spatial variability through comparison with collocated radiosoundings and ECMWF analysis. Perturbations in the wind velocity are used to retrieve gravity wave frequency spectrum.
Annales Geophysicae, 2000
Atmospheric Chemistry and Physics, 2018
Atmospheric Measurement Techniques, 2019
Journal of Geophysical Research: Atmospheres, 2015
Atmospheric Chemistry and Physics Discussions, 2010
Atmospheric Measurement Techniques Discussions, 2014
Atmospheric Measurement Techniques, 2013
Earth System Science Data, 2013
Journal of Geophysical Research: Atmospheres, 2006
The Global Ozone Monitoring by Occultation of Stars (GOMOS) instrument on board the European Spac... more The Global Ozone Monitoring by Occultation of Stars (GOMOS) instrument on board the European Space Agency's Envisat satellite measures ozone and a few other trace gases using the stellar occultation method. Global coverage, good vertical resolution and the self‐calibrating measurement method make GOMOS observations a promising data set for building various climatologies. In this paper we present the nighttime stratospheric ozone distribution measured by GOMOS in 2003. We show monthly latitudinal distributions of the ozone number density and mixing ratio profiles, as well as the seasonal variations of profiles at several latitudes. The stratospheric profiles are compared with the Fortuin‐Kelder daytime ozone climatology. Large differences are found in polar areas and they can be shown to be correlated with large increases of NO2. In the upper stratosphere, ozone values from GOMOS are systematically larger than in the Fortuin‐Kelder climatology, which can be explained by the diurn...
Journal of Geophysical Research: Atmospheres, 2007
Nighttime remote‐sensing balloon observations conducted by the SALOMON instrument in the arctic p... more Nighttime remote‐sensing balloon observations conducted by the SALOMON instrument in the arctic polar vortex in January 2006 reveal high amounts of stratospheric NO2 in the lower stratosphere similarly to previously published profiles. NO2 concentration enhancements are also present in the vertical profiles observed by the GOMOS instrument on board the Envisat satellite and obtained coincidently to the balloon measurements. Such quantities are not present in in situ observations obtained by the SPIRALE instrument in similar geophysical conditions. While OClO amounts are acceptably reproduced by Chemistry Transport Model (CTM) calculations, NO2 simulated values are well below the observed quantities. The examination of the slant column densities of NO2 obtained at float altitude highlights unexpected strong enhancements with respect to the elevation angle and displacement of the balloon. It is shown that these fluctuations result from NO2 spatial inhomogeneities located above the bal...
Journal of Geophysical Research: Atmospheres, 2010
This publication provides a detailed study of one cirrus cloud observed by lidar at the Observato... more This publication provides a detailed study of one cirrus cloud observed by lidar at the Observatory of Haute‐Provence (∼44°N) in January 2006 in the vicinity of the tropopause (12–14 km/∼136–190 hPa/328–355 K). The higher part of the air mass observed comes from the wet subtropics while the lower part comes from the midlatitudes. Both are advected by the Azores anticyclone, encounter cold temperatures (∼205 K) above the North Atlantic Ocean, and flow eastward along the anticyclonic flank of the polar jet stream. A simulation of this cloud by an isentropic model is tested to see if synoptic‐scale atmospheric structures could explain by itself the presence of such clouds. The developments made in the Modélisation Isentrope du transport Méso‐échelle de l'Ozone Stratosphérique par Advection (MIMOSA) model to take into account the three phases of water and their interactions allow reproduction of the occurrence of the cirrus and its temporal evolution. MIMOSA‐H2O reproduces the atmos...
Journal of Geophysical Research: Atmospheres, 2005
In September 2002 the Antarctic polar vortex split in two under the influence of a sudden warming... more In September 2002 the Antarctic polar vortex split in two under the influence of a sudden warming. During this event, the Odin satellite was able to measure both ozone (O3) and chlorine monoxide (ClO), a key constituent responsible for the so‐called “ozone hole”, together with nitrous oxide (N2O), a dynamical tracer, and nitric acid (HNO3) and nitrogen dioxide (NO2), tracers of denitrification. The submillimeter radiometer (SMR) microwave instrument and the Optical Spectrograph and Infrared Imager System (OSIRIS) UV‐visible light spectrometer (VIS) and IR instrument on board Odin have sounded the polar vortex during three different periods: before (19–20 September), during (24–25 September), and after (1–2 and 4–5 October) the vortex split. Odin observations coupled with the Reactive Processes Ruling the Ozone Budget in the Stratosphere (REPROBUS) chemical transport model at and above 500 K isentropic surfaces (heights above 18 km) reveal that on 19–20 September the Antarctic vortex...
Journal of Geophysical Research: Atmospheres, 2005
The Global Ozone Monitoring by Occultation of Stars (GOMOS) stellar occultation instrument on boa... more The Global Ozone Monitoring by Occultation of Stars (GOMOS) stellar occultation instrument on board the Envisat European satellite provides global coverage of ozone and other stratospheric species with good vertical resolution and a self‐calibrating method. In this paper we present the first simultaneous global distribution of stratospheric NO2 and NO3 from 1 year of nighttime GOMOS data in 2003. Most previous NO2 satellite observations have been made using the solar occultation technique. They are difficult to interpret due to the fast photochemical evolution of NO2 at sunrise and sunset. There are no published observations of NO3 from space because this constituent is rapidly photodissociated during daytime and is not observable by solar occultation. It is shown that the NO2 mixing ratio reaches a maximum around 40 km with values between 14 and 16 ppbv at low and middle latitudes. The global distribution of NO2 observed by GOMOS is very similar to the NO + NO2 Halogen Occultation ...
Journal of Geophysical Research: Atmospheres, 1996