Alain Hauchecorne - Academia.edu (original) (raw)

Papers by Alain Hauchecorne

GOMOS on ENVISAT (launched in February, 2002) is the first space instrument dedicated to the stud... more GOMOS on ENVISAT (launched in February, 2002) is the first space instrument dedicated to the study of the atmosphere of the Earth by the technique of stellar occultations (Global Ozone Monitoring by Occultation of Stars). From a polar orbit, it allows to have a good latitude coverage. Because it is self-calibrated, it is particularly well adapted to the long time trend monitoring of stratospheric species. With 4 spectrometers the wavelength coverage of 248 nm to 942 nm allows to monitor ozone, H 2 O, NO 2 , NO 3 , air, aerosols, and O 2. Two additional fast photometers (1 kHz sampling rate) allow for the correction of scintillations, as well as the study of the structure of air density irregularities, resulting from gravity waves and turbulence. A high vertical resolution profile of the temperature may also be obtained from the time delay between the red and the blue photometer. Noctilucent clouds (Polar Mesospheric Clouds, PMC), are routinely observed in both polar summers, and global observations of OCLO and sodium are achieved. The instrument configuration, dictated by the scientific objectives rationale and technical constraints, are described, together with the typical operations along one orbit, and statistics over 5 years of operation. Typical atmospheric transmission spectra are presented, and some retrieval difficulties are discussed, in particular for O 2 and H 2 O. An overview of a number of scientific results is presented, already published or found in more details as companion papers in the same ACP GOMOS special issue. This paper is particularly intended to provide the incentive for GOMOS data exploitation, available to the whole scientific community in the ESA data archive, and to help the GOMOS data users to better understand the instrument, its capabilities and the quality of its measurements, for an optimized scientific return.

The Global Ozone Monitoring by Occultation of Stars (GOMOS) instrument on board the European plat... more The Global Ozone Monitoring by Occultation of Stars (GOMOS) instrument on board the European platform ENVISAT was dedicated to the study of the atmosphere of the Earth using the stellar occultation technique. The spectral range of the GOMOS spectrometer extends from the UV to the near infrared, allowing for the retrieval of species such as O 3 , NO 2 , NO 3 , H 2 O, O 2 , air density, aerosol extinction and OClO. Nevertheless, OClO can not be retrieved using a single GOMOS measurement because of the weak signal-to-noise ratio and the small optical thickness associated with this molecule. We present here the method used to detect this molecule by using several GOMOS measurements. It is based on a two-step approach. First, several co-located measurements are combined in a statistical way to build an averaged measurement with a higher signal-to-noise ratio. Then, a Differential Optical Absorption Spectroscopy (DOAS) method is applied to retrieve OClO slant column densities. The statistics of the sets of GOMOS measurements used to build the averaged measurement and the spectral window selection are analyzed. The obtained retrievals are compared to results from two balloon-borne instruments. It appears that the inter-comparisons of OClO are generally satisfying. Then, two nighttime climatologies of OClO slant column densities based on GOMOS averaged measurements are presented. The first depicts annual global pictures of OClO from 2003 to 2011. From this climatology, the presence of an OClO layer in the equatorial region at about 35 km is confirmed and strong concentrations of OClO in both polar regions are observed, a sign of chlorine activation. The second climatology is a monthly time series. It clearly shows the chlorine activation of the lower stratosphere during winter. Moreover the equatorial OClO layer is observed during all the years without any significant variations. Finally, the anti-correlation between OClO and NO 2 is highlighted. This very promising method, applied on GOMOS measurements, allowed us to build the first nighttime climatology of OClO.

HIBISCUS was a field campaign for investigating the impact of deep convection on the Tropical Tro... more HIBISCUS was a field campaign for investigating the impact of deep convection on the Tropical Tropopause Layer (TTL) and the Lower Stratosphere, which took place during the Southern Hemisphere summer in February-March 2004 in the State of São Paulo, Brazil. Its objective was to provide a set of new observational data on meteorology, tracers of horizontal and vertical transport, water vapour, clouds, and chemistry in the tropical UT/LS from balloon observations at local scale over a land convective area, as well as at global scale using circumnavigating long-duration balloons. Overall, the composition of the TTL, the region between 14 and 19 km of intermediate lapse rate between the almost adiabatic upper troposphere and the stable stratosphere, appears

The article presents new high-quality continuous stratospheric aerosol observations spanning 1994... more The article presents new high-quality continuous stratospheric aerosol observations spanning 1994-2015 at the French Observatoire de Haute-Provence (OHP, 44 °N, 6 °E) obtained by two independent regularly-maintained lidar systems. Lidar series are compared with global-coverage observations by Stratospheric Aerosol and Gas Experiment (SAGE II), Global Ozone Monitoring by Occultation of Stars (GOMOS), Optical Spectrograph and InfraRed Imaging System (OSIRIS), Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and Ozone Mapping Profiling Suite (OMPS) satellite instruments, altogether covering the time span of OHP lidar measurements. Local OHP and zonal-mean satellite series of stratospheric aerosol optical depth are in excellent agreement, allowing for accurate characterization of stratospheric aerosol evolution and variability at Northern mid-latitudes during the post-Pinatubo era. The combination of local and global observations is used for careful separation between volcanically-perturbed and quiescent periods. While the volcanic signatures dominate the stratospheric aerosol record, the background aerosol abundance is found to be modulated remotely by poleward transport of convectively-cleansed air from the deep tropics and aerosol-laden air from the Asian monsoon region. The annual cycle of background aerosol at mid-latitudes, featuring a minimum during late spring and a maximum during late summer, correlates with that of water vapour from Microwave Limb Sounder (MLS). Observations covering two volcanically-quiescent periods over the last two decades provide indication of a growth in the non-volcanic component of stratospheric aerosol. A statisticallysignificant factor of two increase of non-volcanic aerosol since 1998, seasonally restricted to latesummer and fall, is associated with the influence of the Asian monsoon and growing pollution therein.

In this paper, we describe the inversion algorithm for retrievals of high vertical resolution tem... more In this paper, we describe the inversion algorithm for retrievals of high vertical resolution temperature profiles (HRTPs) using bichromatic stellar scintillation measurements in the occultation geometry. This retrieval algorithm has been improved with respect to nominal ESA processing and applied to the measurements by Global Ozone Monitoring by Occultation of Stars (GOMOS) operated on board Envisat in 2002-2012. The retrieval method exploits the chromatic refraction in the Earth's atmosphere. The bichromatic scintillations allow the determination of the refractive angle, which is proportional to the time delay between the photometer signals. The paper discusses the basic principle and detailed inversion algorithm for reconstruction of highresolution density, pressure and temperature profiles in the stratosphere from scintillation measurements. The HRTPs are retrieved with a very good vertical resolution of ∼ 200 m and high precision (random uncertainty) of ∼ 1-3 K for altitudes of 15-32 km and with a global coverage. The best accuracy is achieved for in-orbital-plane occultations, and the precision weakly depends on star brightness. The whole GO-MOS dataset has been processed with the improved HRTP inversion algorithm using the FMI's scientific processor; and the dataset (HRTP FSP v1) is in open access. The validation of small-scale fluctuations in the retrieved HRTPs is performed via comparison of vertical wavenumber spectra of temperature fluctuations in HRTPs and in collocated radiosonde data. We found that the spectral features of temperature fluctuations are very similar in HRTPs and collocated radiosonde temperature profiles. HRTPs can be assimilated into atmospheric models, used in studies of stratospheric clouds and used for the analysis of internal gravity waves' activity. As an example of geophysical applications, gravity wave potential energy has been estimated using the HRTP dataset. The obtained spatiotemporal distributions of gravity wave energy are in good agreement with the previous analyses using other measurements. Published by Copernicus Publications on behalf of the European Geosciences Union. V. F. Sofieva et al.: High-resolution temperature profiles Figure 9. Mean uncertainties of HRTPs in the equatorial region (20 • S-20 • N) in 2004, for different obliquity angles β, specified in the panels, and for different stars: bright (m < 1), medium (1 < m < 2.5) and dim (m > 2.5).

Journal of Geophysical Research, 1991

The technique of the Rayleigh lidar provides temperature profiles with a good temporal and vertic... more The technique of the Rayleigh lidar provides temperature profiles with a good temporal and vertical resolution in the middle atmosphere. Data obtained by 2 Rayleigh lidars set up at the Observatory of Haute-Provence (44øN, 6øE) and at Biscarrosse (44øN, IøW) from 1978 to 1989 led to a unique set of data of 1200 night-mean temperature profiles from 37 to 87 km. A climatology of the temperature over the south of France has been established from this data base and new results concerning both the shortterm and long-term variability of the middle atmosphere are presented in this paper. The observed temperature around 44øN, 0øW is in general colder than the mean temperature given in the COSPAR International Reference Atmosphere (1986) near 75 km and warmer above 80 km. A clear semiannual variation is observed near 65 km with maxima occurring just after the equinoxes. The study of the short-term variability indicates clearly two frequency domains: long periods below 65 km with a maximum in December-January which relate to planetary waves and shorter periods above 65 km induced by the breaking of gravity waves. A correlation with the 11-year solar cycle, negative in the stratosphere and positive in the mesosphere, is found to be well above the 95% confidence level with an amplitude larger in winter than in summer. However, with only 11 years of data it is obviously difficult to conclude that this atmospheric perturbation is induced by the solar forcing. A cooling of the mesosphere of about-4 K/decade at 60-70 km is found but is at the limit of the 95% confidence level, whereas we do not observe any significant trend in the stratosphere. 15,297 15,298 Hauchecorne et al.: Rayleigh Lidar Temperature Climatology Table 1. Lidar characteristics OHP BIS Emission Laser Nd-YAG Nd-YAG Wavelength 532 nm 532 nm Repetition rate 15 Hz 30 Hz Energy per shot 400 mJ 200 mJ Divergence 1.10-4 rad 1.10-4 rad Reception Telescope diameter 80 cm 120 cm Field of view 2.10-4 rad 2.10-4 rad Distance emission-reception 60 cm coaxial Vertical resolution 300 m 300 m Detection mode photon counting photon counting Spectral bandwidth 1 mn 1 nm (day 20 pm) Period of operation Low altitude channel Semi-automatic mode Daytime measurement Operation mode

We present the first nighttime measurements of OClO from a limb-viewing satellite instrument in t... more We present the first nighttime measurements of OClO from a limb-viewing satellite instrument in the Arctic polar vortex. The relationship between OClO, NO 2 and O 3 slant column densities in the Arctic polar vortex are analyzed from the GOMOS measurements. The retrieval process is based on a differential optical absorption spectroscopy (DOAS) method applied on the weighted median GOMOS transmittances. A study about the longitudinal distributions of OClO, NO 2 and O 3 above 65 • north in January 2008 is presented. It shows a strong halogen activation in the lower stratosphere and a strong denoxification in the entire stratosphere inside the Arctic polar vortex. Time series of temperatures and OClO, NO 2 and O 3 slant column densities for the winters 2002/2003 to 2007/2008 are also presented. They highlight the correlation between temperature, OClO and NO 2. The GOMOS instrument appears to be a very suitable instrument for the monitoring of OClO, NO 2 and O 3 in the stratosphere during nighttime.

Atmospheric Measurement Techniques, Oct 22, 2020

A two-part intercomparison campaign was conducted at Observatoire de Haute-Provence (OHP) for the... more A two-part intercomparison campaign was conducted at Observatoire de Haute-Provence (OHP) for the validation of lidar ozone and temperature profiles using the mobile NASA Stratospheric Ozone Lidar (NASA STROZ), satellite overpasses from the Microwave Limb Sounder (MLS), the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER), meteorological radiosondes launched from Nîmes, and locally launched ozonesondes. All the data were submitted and compared "blind", before the group could see results from the other instruments. There was good agreement between all ozone measurements between 20 and 40 km, with differences of generally less than 5 % throughout this region. Below 20 km, SABER and MLS measured significantly more ozone than the lidars or ozonesondes. Temperatures for all lidars were in good agreement between 30 and 60 km, with differences on the order of ±1 to 3 K. Below 30 km, the OHP lidar operating at 532 nm has a significant cool bias due to contamination by aerosols. Systematic, altitude-varying bias up to ±5 K compared to the lidars was found for MLS at many altitudes. SABER temperature profiles are generally closer to the lidar profiles, with up 3 K negative bias near 50 km. Total uncertainty estimates for ozone and temperature appear to be realistic for nearly all systems. However, it does seem that the very low estimated uncertainties of lidars between 30 and 50 km, between 0.1 and 1 K, are not achieved during Lidar Validation Network for the Detection of Atmospheric Composition Change (NDACC) Experiment (LAVANDE). These estimates might have to be increased to 1 to 2 K.

Geophysical Research Letters, Feb 24, 2015

Seven year series of gravity wave (GW) potential energy at midlatitude stratosphere (10 to 50 km)... more Seven year series of gravity wave (GW) potential energy at midlatitude stratosphere (10 to 50 km) is constructed by combining temperature profiles provided by Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) GPS satellite constellation and Rayleigh lidar operating at Haute Provence observatory in Southern France. The combined series are used to evaluate the representation of GW in Modern Era Retrospective-Analysis for Research and Applications reanalysis. The seasonal and zonal variabilities of GW activity are diagnosed using zonal wind and wind divergence provided by ERA-Interim reanalysis. The spatiotemporal distribution of GW activity is found strongly dependent on the zonal wind variation, wind divergence, and topography. We show that anomalies in the wind divergence can serve as a proxy for locating synoptic-scale enhancements of GW. The analysis provides evidence for orographic GW excitation, and the results are compatible with geostrophic adjustment being an additional source of stratospheric GW. The seasonal GW variability can be largely explained by interaction with the mean flow and wave propagation.

The Global Ozone Monitoring by Occultation of Stars (GOMOS) instrument uses stellar occultation t... more The Global Ozone Monitoring by Occultation of Stars (GOMOS) instrument uses stellar occultation technique for monitoring ozone and other trace gases in the stratosphere and mesosphere. The self-calibrating measurement principle of GOMOS together with a relatively simple data retrieval where only minimal use of a priori data is required, provides excellent possibilities for long term monitoring of atmospheric composition. GOMOS uses about 180 brightest stars as the light source. Depending on the individual spectral characteristics of the stars, the signal-to-noise ratio of GOMOS is changing from star to star, resulting also varying accuracy to the retrieved profiles. We present the overview of the GOMOS data characterization and error estimation, including modeling errors, for ozone, NO 2 , NO 3 and aerosol profiles. The retrieval error (precision) of the night time measurements in the stratosphere is typically 0.5-4% for ozone, about 10-20% for NO 2 , 20-40% for NO 3 and 2-50% for aerosols. Mesospheric O 3 , up to 100 km, can be measured with 2-10% precision. The main sources of the modeling error are the incompletely corrected atmospheric turbulence causing scintillation, inaccurate aerosol modeling, uncertainties in cross sections of the trace gases and in the atmospheric temperature. The sampling resolution of GOMOS varies depending on the measurement geometry. In the data inversion a Tikhonov-type regularization with pre-defined target resolution requirement is applied leading to 2-3 km resolution for ozone and 4 km resolution for other trace gases.

Springer eBooks, Oct 27, 2018

Journal Of Geophysical Research: Atmospheres, Dec 4, 2020

French Antarctic Dumont d'Urville station 2. A dedicated simple microphysical and transport model... more French Antarctic Dumont d'Urville station 2. A dedicated simple microphysical and transport model uses CALIOP data as constraints to successfully model the aerosol overpass above Antarctica 3. Positive ozone anomaly is reported using lidar measurements Plain Language Summary: A series of bushfires ignited in the Australian state of Victoria on February 7th 2009 and ended up being the most devastating fire hazard in Australia before the recent 2019/2020 fires. Active remote sensing monitoring instruments are deployed on the French Antarctic station Dumont d'Urville. For the first time, the station recorded presence of aerosols having originated from this biomass burning event at stratospheric altitudes using the atmospheric laser sounding technique (lidar). We combine model calculations to space-borne and ground-based measurements to track the long-range transport of a small filament of the aerosol plume down to the Antarctic station to highlight the possible global impact of such events.

Atmospheric Measurement Techniques, Jan 20, 2017

Atmospheric Chemistry and Physics, Apr 22, 2021

Using a global network of temperature lidars to identify temperature biases in the upper stratosp... more Using a global network of temperature lidars to identify temperature biases in the upper stratosphere in ECMWF reanalyses. Atmospheric Chemistry and Physics Discussions, 21. pp. 6079-6092.

Atmospheric Chemistry and Physics, Dec 13, 2010

The GOMOS ozone profiles have been analysed to evaluate the GOMOS ability to capture the long-ter... more The GOMOS ozone profiles have been analysed to evaluate the GOMOS ability to capture the long-term ozone evolution at mid-latitudes during the expected recovery phase of the ozone layer. Version 5 of the operational GOMOS ozone data has been compared with data from two of the longest ground-based instruments based on different techniques and already involved with many other previous space instrument validations. Comparisons between ground-based and GOMOS data confirm the occurrence of spurious retrievals mainly occurring since 2006. Using a selected set of data it is shown that some bad retrievals are induced by the increasing dark charge of the detectors combined with an inadequate method for its correction. This effect does not only induce a continuous bias, but is rather exhibiting a bimodal distribution including the correct profiles and the bad retrievals. For long-term analyses it is recommended filtering the data according to background light conditions and star temperature (spectrum shape). The new method of the dark charge estimate proposed to be implemented in the version 6 of the ESA algorithm seems to significantly reduce the occurrence of such effects and should allow to monitor stratospheric ozone using GOMOS data with greater confidence.

Atmospheric Chemistry and Physics, Jul 9, 2009

We present spatio-temporal distributions of the tertiary ozone maximum (TOM), based on GOMOS (Glo... more We present spatio-temporal distributions of the tertiary ozone maximum (TOM), based on GOMOS (Global Ozone Monitoring by Occultation of Stars) ozone measurements in 2002-2006. The tertiary ozone maximum is typically observed in the high-latitude winter mesosphere at an altitude of ∼72 km. Although the explanation for this phenomenon has been found recently-low concentrations of odd-hydrogen cause the subsequent decrease in odd-oxygen losses-models have had significant deviations from existing observations until recently. Good coverage of polar night regions by GOMOS data has allowed for the first time to obtain spatial and temporal observational distributions of night-time ozone mixing ratio in the mesosphere. The distributions obtained from GOMOS data have specific features, which are variable from year to year. In particular, due to a long lifetime of ozone in polar night conditions, the downward transport of polar air by the meridional circulation is clearly observed in the tertiary ozone maximum time series. Although the maximum tertiary ozone mixing ratio is achieved close to the polar night terminator (as predicted by the theory), TOM can be observed also at very high latitudes, not only in the beginning and at the end, but also in the middle of winter. We have compared the observational spatiotemporal distributions of the tertiary ozone maximum with that obtained using WACCM (Whole Atmosphere Community Climate Model) and found that the specific features are reproduced satisfactorily by the model.

Atmospheric Chemistry and Physics, Feb 7, 2017

The article presents new high-quality continuous stratospheric aerosol observations spanning 1994... more The article presents new high-quality continuous stratospheric aerosol observations spanning 1994-2015 at the French Observatoire de Haute-Provence (OHP, 44 • N, 6 • E) obtained by two independent, regularly maintained lidar systems operating within the Network for Detection of Atmospheric Composition Change (NDACC). Lidar series are compared with global-coverage observations by Stratospheric Aerosol and Gas Experiment (SAGE II), Global Ozone Monitoring by Occultation of Stars (GO-MOS), Optical Spectrograph and InfraRed Imaging System (OSIRIS), Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), and Ozone Mapping Profiling Suite (OMPS) satellite instruments, altogether covering the time span of OHP lidar measurements. Local OHP and zonal-mean satellite series of stratospheric aerosol optical depth are in excellent agreement, allowing for accurate characterization of stratospheric aerosol evolution and variability at northern midlatitudes during the last 2 decades. The combination of local and global observations is used for a careful separation between volcanically perturbed and quiescent periods. While the volcanic signatures dominate the stratospheric aerosol record, the background aerosol abundance is found to be modulated remotely by the poleward transport of convectively cleansed air from the deep tropics and aerosol-laden air from the Asian monsoon region. The annual cycle of background aerosol at midlatitudes, featuring a minimum during late spring and a maximum during late summer, correlates with that of water vapor from the Aura Microwave Limb Sounder (MLS). Observations covering two volcanically quiescent periods over the last 2 decades provide an indication of a growth in the nonvolcanic component of stratospheric aerosol. A statistically significant factor of 2 increase in nonvolcanic aerosol since 1998, seasonally restricted to late summer and fall, is associated with the influence of the Asian monsoon and growing pollution therein. 1 Introduction The role of the stratospheric aerosol burden in climate variability and ozone chemistry is well recognized. Long-term observations of stratospheric aerosol are essential for the in-Published by Copernicus Publications on behalf of the European Geosciences Union.

Geophysical Research Letters, May 2, 2023

We have compared 2433 nights of Rayleigh lidar temperatures measured at L'Observatoire de Haute P... more We have compared 2433 nights of Rayleigh lidar temperatures measured at L'Observatoire de Haute Provence (OHP) with co-located temperature measurements from the Microwave Limb Sounder (MLS) and the Sounding of the Atmosphere by Broadband Emission Radiometry instrument (SABER). The comparisons were conducted using data from January 2002 to March 2018 in the geographic region around the observatory (43.93 • N, 5.71 • E). We have found systematic differences between the temperatures measured from the ground-based lidar and those measured from the satellites, which suggest non-linear distortions in the satellite altitude retrievals. We see a winter stratopause cold bias in the satellite measurements with respect to the lidar (−6 K for SABER and −17 K for MLS), a summer mesospheric warm bias (6 K near 60 km), and a vertically structured bias for MLS (−4 to 4 K). We have corrected the stratopause height of the satellite measurements using the lidar temperatures and have seen an improvement in the comparison. The winter relative cold bias between the lidar and SABER has been reduced to 1 K in both the stratosphere and mesosphere and the summer mesospheric warm bias is reduced to 2 K. Stratopause altitude corrections have reduced the relative cold bias between the lidar and MLS by 4 K in the early autumn and late spring but were unable to address the apparent vertical oscillations in the MLS temperature profiles.

Journal of Geophysical Research, 1991

Atmospheric Measurement Techniques, Oct 22, 2020

Geophysical Research Letters, Feb 24, 2015

Springer eBooks, Oct 27, 2018

Journal Of Geophysical Research: Atmospheres, Dec 4, 2020

Atmospheric Measurement Techniques, Jan 20, 2017

Atmospheric Chemistry and Physics, Apr 22, 2021

Atmospheric Chemistry and Physics, Dec 13, 2010

Atmospheric Chemistry and Physics, Jul 9, 2009

Atmospheric Chemistry and Physics, Feb 7, 2017

The article presents new high-quality continuous stratospheric aerosol observations spanning 1994... more The article presents new high-quality continuous stratospheric aerosol observations spanning 1994-2015 at the French Observatoire de Haute-Provence (OHP, 44 • N, 6 • E) obtained by two independent, regularly maintained lidar systems operating within the Network for Detection of Atmospheric Composition Change (NDACC). Lidar series are compared with global-coverage observations by Stratospheric Aerosol and Gas Experiment (SAGE II), Global Ozone Monitoring by Occultation of Stars (GO-MOS), Optical Spectrograph and InfraRed Imaging System (OSIRIS), Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), and Ozone Mapping Profiling Suite (OMPS) satellite instruments, altogether covering the time span of OHP lidar measurements. Local OHP and zonal-mean satellite series of stratospheric aerosol optical depth are in excellent agreement, allowing for accurate characterization of stratospheric aerosol evolution and variability at northern midlatitudes during the last 2 decades. The combination of local and global observations is used for a careful separation between volcanically perturbed and quiescent periods. While the volcanic signatures dominate the stratospheric aerosol record, the background aerosol abundance is found to be modulated remotely by the poleward transport of convectively cleansed air from the deep tropics and aerosol-laden air from the Asian monsoon region. The annual cycle of background aerosol at midlatitudes, featuring a minimum during late spring and a maximum during late summer, correlates with that of water vapor from the Aura Microwave Limb Sounder (MLS). Observations covering two volcanically quiescent periods over the last 2 decades provide an indication of a growth in the nonvolcanic component of stratospheric aerosol. A statistically significant factor of 2 increase in nonvolcanic aerosol since 1998, seasonally restricted to late summer and fall, is associated with the influence of the Asian monsoon and growing pollution therein. 1 Introduction The role of the stratospheric aerosol burden in climate variability and ozone chemistry is well recognized. Long-term observations of stratospheric aerosol are essential for the in-Published by Copernicus Publications on behalf of the European Geosciences Union.

Geophysical Research Letters, May 2, 2023