Papers by Sophie Godin-Beekmann
Since June 2005, the CEILAP group with the support of JICA (Japan International Cooperation Agenc... more Since June 2005, the CEILAP group with the support of JICA (Japan International Cooperation Agency) and cooperation with French LATMOS and Japanese researches has carried out systematic measurements of ozone profile and UV radiation in the southern part of Argentina (51°55'S, 69°14'W) using a Differential Absorption lidar (DIAL), this place has been called Atmospheric Observatory of Southern Patagonia (OAPA). After 2006 other products were retrieved in addition to the ozone profiles from the DIAL measurements, such as stratospheric aerosols and temperature profiles using the off ¬wavelength signal at 355 nm. This work presents the improved algorithm used to retrieve temperature from the lidar signals and unusual temperature measurements obtained in November 9. In this work we present the incorporation of a digital filter called Savitky ¬Golay. We have evaluated the cut off frequency of the filter in relation with number of point (N) as a function of cutoff frequency. Through extensive simulations we have found a power law representative of the filter behavior. Also we have incorporated a new climatology temperature profiles database calculated from the model MSISE¬90. As a part the evaluation of this algorithm we have detected an unusual temperature profiles on November 2009 due a depletion of the ozone density. We present the comparison of these profiles measured during November 13¬14 2009, compared with the NCEP mean profiles in Rio Gallegos for the period 2005¬2011. We have found a warming in the higher stratosphere with a temperature anomaly of 25 K around 36 km when the temperature profile was compared with the NCEP mean profile.
Atmospheric Chemistry and Physics, 2018
Abstract. The study presents the climatological character-istics of stratospheric ozone observed ... more Abstract. The study presents the climatological character-istics of stratospheric ozone observed over Reunion Island using in-situ (ozonesonde and SAOZ) and satellite (UARS-HALOE, SAGE-II and TOMS) measurements. It uses co-localised ozonesondes (from September 1992 to February
Annales Geophysicae, 2007
Atmospheric Chemistry and Physics, 2010
The passive tracer method is used to estimate ozone loss from ground-based measurements in the An... more The passive tracer method is used to estimate ozone loss from ground-based measurements in the Antarctic. A sensitivity study shows that the ozone depletion can be estimated within an accuracy of ∼4%. The method is then applied to the ground-based observations from Arrival Heights,
EPJ Web of Conferences, 2016
ECC (Electrochemical Concentration Cell) ozonesondes and UV DIAL (DIfferential Absorption Lidar) ... more ECC (Electrochemical Concentration Cell) ozonesondes and UV DIAL (DIfferential Absorption Lidar) measurements have been carried out simultaneously at OHP (Observatoire de Haute Provence, 44°N, 6.7°E, 690 m) since 1991. A unique long-term trend assessment by two different instruments operated routinely at the same location is possible. Air mass trajectories have been calculated for all the ozone observations available at OHP. The bias between the seasonal mean calculated with lidar and ECC ozone vertical profiles for 4 timeperiods of 5 years is 0.6 ppbv in the free troposphere (4-8 km). Larger differences (> 10 ppbv) are explained by the need for clear sky conditions during lidar observations. The measurements of both instruments have been combined to decrease the impact of short-term atmospheric variability on the trend estimate.
The unusual persistence of an ozone hole over a southern mid-latitude station during the Antarcti... more The unusual persistence of an ozone hole over a southern mid-latitude station during the Antarctic spring 2009: a multi-instrument study
Atmospheric Chemistry and Physics, 2015
A detailed analysis of the polar ozone loss processes during 10 recent Antarctic winters is prese... more A detailed analysis of the polar ozone loss processes during 10 recent Antarctic winters is presented with high-resolution MIMOSA-CHIM (Modèle Isentrope du transport Méso-échelle de l'Ozone Stratosphérique par Advection avec CHIMie) model simulations and high-frequency polar vortex observations from the Aura microwave limb sounder (MLS) instrument. The high-frequency measurements and simulations help to characterize the winters and assist the interpretation of interannual variability better than either data or simulations alone. Our model results for the Antarctic winters of 2004-2013 show that chemical ozone loss starts in the edge region of the vortex at equivalent latitudes (EqLs) of 65-67 • S in mid-June-July. The loss progresses with time at higher EqLs and intensifies during August-September over the range 400-600 K. The loss peaks in late September-early October, when all EqLs (65-83 • S) show a similar loss and the maximum loss (> 2 ppmv-parts per million by volume) is found over a broad vertical range of 475-550 K. In the lower stratosphere, most winters show similar ozone loss and production rates. In general, at 500 K, the loss rates are about 2-3 ppbv sh −1 (parts per billion by volume per sunlit hour) in July and 4-5 ppbv sh −1 in August-mid-September, while they drop rapidly to 0 by mid-October. In the middle stratosphere, the loss rates are about 3-5 ppbv sh −1 in July-August and October at 675 K. On average, the MIMOSA-CHIM simulations show that the very cold winters of 2005 and 2006 exhibit a maximum loss of
The Mount Pinatubo Eruption, 1996
The decay of the Mt. Pinatubo volcanic cloud was monitored by systematic groundbased aerosol lida... more The decay of the Mt. Pinatubo volcanic cloud was monitored by systematic groundbased aerosol lidar systems implemented at the Observatoire de Haute-Provence (OHP, 44°N, 6°E) and at the Antarctic station of Dumont d’Urville (66.4°S, 140°E) Additional backscatter lidar measurements were also performed during the EASOE campaign in Sodankyla (67°N, 26°E). At northern mid-latitude, comparisons with the El Chichon volcanic cloud indicates similar aerosol loading but a longer residence time of the volcanic aerosols especially in the 15- 20 km altitude range. The analysis of the aerosol measurements obtained at the northern and southern polar latitudes shows that mixing can take place at the edge of the polar vortex in the lower stratosphere whereas the vortex remains mainly isolated above, especially in the southern hemisphere. The measurements performed in the winter and spring of 1992 in Dumont d’Urville allow to evaluate the subsidence of air inside the vortex, at a rate of 1 km/month at the 475 K potential temperature level. Besides, an ozone decrease of about 20 % as compared to the long-term climatology was recorded on the ozone sonde measurements performed at OHP in the 17 km to 22 km altitude range, in 1992 - 1993. The maximum depletion was found at the beginning of 1993, when it reached 30 % around 17 km, below the 2 sigma long term variability.
Comptes Rendus de l'Académie des Sciences - Series IIA - Earth and Planetary Science, 1998
Average subsidence in the Antarctic lower stratosphere for the austral fall of 1994 and 1996 and ... more Average subsidence in the Antarctic lower stratosphere for the austral fall of 1994 and 1996 and ozone destruclion rates during the spring are derived.from ozone measurements made at Dumont d'llrville (140. lE, 6.6.4s). Y&e comparison with POAM II data suggests that ozone destruction within the r)ortex starts earlier on the edge than in the centre. TBe vortex sam@ling in 1996ahws us to study the vortex confinement and to confirm its role of hohating har&r ahove 400 K. 0 Acadhie des sciences / I?lsesier, Paris.
Advances in Atmospheric Remote Sensing with Lidar, 1997
Scattering ratios R processed from the same rawdata at 353 and 532 nm by different lidar groups a... more Scattering ratios R processed from the same rawdata at 353 and 532 nm by different lidar groups agree within about 10% for high and within about 4% for low aerosol loading. In the main layer aerosol backscatter coefficients agree within about 30% for high and within about 40% for low aerosol loading
Report describes selected aspects of underlying theory, design, and operation of ground-based, hi... more Report describes selected aspects of underlying theory, design, and operation of ground-based, high-power, pulsed lidar system measuring concentration of stratospheric ozone as function of altitude.
The subtropical dynamical barrier, located in the lower stratosphere on the edge of the Tropical ... more The subtropical dynamical barrier, located in the lower stratosphere on the edge of the Tropical Stratospheric Reservoir (TSR), controls and limits exchanges between tropical and extratropical stratospheres. Moreover, the position and width of the TSR boundaries show an annual variation and are function of the phase of QBO [Grant et al.,1996]. Isentropic transport between TSR and midlatitudes is also linked
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Papers by Sophie Godin-Beekmann