During a recent 2020 campaign, the Rayleigh lidar aboard the Bâtiment d’Essais et de Mesures (BEM) Monge conducted high-resolution temperature measurements of the upper Mesosphere and Lower Thermosphere (MLT). These measurements were used to conduct the first validation of ICON-MIGHTI temperatures by Rayleigh lidar. A double Mesospheric Inversion Layer (MIL) as well as shorter-period gravity waves was observed. Zonal and meridional wind speeds were obtained from locally launched radiosondes and the newly launched ICON satellite as well as from the European Centre for Medium-Range Weather Forecasts (ECMWF-ERA5) reanalysis. These three datasets allowed us to see the evolution of the winds in response to the forcing from the MIL and gravity waves. The wavelet analysis of a case study suggests that the wave energy was dissipated in small, intense, transient instabilities about a given wavenumber in addition to via a broad spectrum of breaking waves. This article will also detail the recent hardware advances of the Monge lidar that have allowed for the measurement of MILs and gravity waves at a resolution of 5 min with an effective vertical resolution of 926 m.

The Advanced Test Range Ship Monge (ATRSM) is dedicated to in-flight measurements during the re-entry phase of ballistic missiles test flights. Atmospheric density measurements from 15 to 110 km are provided using one of the world’s largest Rayleigh lidars. This lidar is the culmination of three decades of French research experience in lidar technologies, developed within the framework of the global Network for Detection of Atmospheric and Climate Changes (NDACC), and opens opportunities for high resolution Rayleigh lidar studies above 90 km. The military objective of the ATRSM project is to provide near real time estimates of the atmospheric relative density profile, with an error budget of less than 10% at 90 km altitude, given a temporal integration of 15 min and a vertical resolution of 500 m. To achieve this aim we have developed a unique lidar system which exploits six laser transmitters and a constellation of eight receiving telescopes which maximises the lidar power-aperture product. This system includes a mix of standard commercially available optical components and electronics as well as some innovative technical solutions. We have provided a detailed assessment of some of the more unique aspects of the ATRSM lidar.

The first operations at the new High-altitude Maido Observatory at La Reunion began in 2013. The Maido Lidar Calibration Campaign (MALICCA) was organized there in April 2013 and has focused on the validation of the thermodynamic parameters (temperature, water vapor, and wind) measured with many instruments including the new very large lidar for water vapor and temperature profiles. The aim of this publication consists of providing an overview of the different instruments deployed during this campaign and their status, some of the targeted scientific questions and associated instrumental issues. Some specific detailed studies for some individual techniques were addressed elsewhere. This study shows that temperature profiles were obtained from the ground to the mesopause (80 km) thanks to the lidar and regular meteorological balloon-borne sondes with an overlap range showing good agreement. Water vapor is also monitored from the ground to the mesopause by using the Raman lidar and microwave techniques. Both techniques need to be pushed to their limit to reduce the missing range in the lower stratosphere. Total columns obtained from global positioning system or spectrometers are valuable for checking the calibration and ensuring vertical continuity. The lidar can also provide the vertical cloud structure that is a valuable complementary piece of information when investigating the water vapor cycle. Finally, wind vertical profiles, which were obtained from sondes, are now also retrieved at Maido from the newly implemented microwave technique and the lidar. Stable calibrations as well as a small-scale dynamical structure are required to monitor the thermodynamic state of the middle atmosphere, ensure validation of satellite sensors, study the transport of water vapor in the vicinity of the tropical tropopause and study their link with cirrus clouds and cyclones and the impact of small-scale dynamics (gravity waves) and their link with the mean state of the mesosphere. (C) 2015 Society of Photo-Optical Instrumentation Engineers (SPIE)

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Multi-year sets of ground-based sun-photometer measurements conducted at 12 Arctic sites and 9 Antarctic sites were examined to determine daily mean values of aerosol optical thickness tau(lambda) at visible and near-infrared wavelengths, from which best-fit values of Angstrom's exponent alpha were calculated. Analysing these data, the monthly mean values of tau(0.50 mu m) and alpha and the relative frequency histograms of the daily mean values of both parameters were determined for winter spring and summer autumn in the Arctic and for austral summer in Antarctica. The Arctic and Antarctic covariance plots of the seasonal median values of alpha versus tau(0.50 mu m) showed: (i) a considerable increase in tau(0.50 mu m) for the Arctic aerosol from summer to winter spring, without marked changes in alpha; and (ii) a marked increase in tau(0.50 mu m) passing from the Antarctic Plateau to coastal sites, whereas alpha decreased considerably due to the larger fraction of sea-salt aerosol. Good agreement was found when comparing ground-based sun-photometer measurements of tau(lambda) and alpha at Arctic and Antarctic coastal sites with Microtops measurements conducted during numerous AERONET/MAN cruises from 2006 to 2013 in three Arctic Ocean sectors and in coastal and off-shore regions of the Southern Atlantic, Pacific, and Indian Oceans, and the Antarctic Peninsula.Lidar measurements were also examined to characterise vertical profiles of the aerosol backscattering coefficient measured throughout the year at Ny-Alesund. Satellite-based MODIS, MISR, and AATSR retrievals of tau(lambda) over large parts of the oceanic polar regions during spring and summer were in close agreement with ship-borne and coastal ground-based sun-photometer measurements. An overview of the chemical composition of mode particles is also presented, based on in-situ measurements at Arctic and Antarctic sites. Fourteen log-normal aerosol number size-distributions were defined to represent the average features of nuclei, accumulation and coarse mode particles for Arctic haze, summer background aerosol, Asian dust and boreal forest fire smoke, and for various background austral summer aerosol types at coastal and high-altitude Antarctic sites. The main columnar aerosol optical characteristics were determined for all 14 particle modes, based on in-situ measurements of the scattering and absorption coefficients. Diurnally averaged direct aerosol-induced radiative forcing and efficiency were calculated for a set of multimodal aerosol extinction models, using various Bidirectional Reflectance Distribution Function models over vegetation-covered, oceanic and snow-covered surfaces. These gave a reliable measure of the pronounced effects of aerosols on the radiation balance of the surface-atmosphere system over polar regions. (C) 2014 Elsevier B.V. All rights reserved.

Observations of ozone are performed with lidar and ozonesondes at Reunion Island University (21°S,55°E) since the 90s. These observations display the annual cycle of free tropospheric ozone, in relation with the seasonnality of austral biomass burning and stratosphere-troposphere exchange (Clain et al., 2010). In order to further characterize the transport and physico-chemical impact of trace gases and aerosols over Indian Ocean, we analyse : - African biomass burning emission GFED2 and GDRIBB inventories in 2009-2010. - carbon monoxide partial columns obtained with FTIR at Reunion Island in 2007. - aerosol measurements with lidar and photometer on board the Marion Dufresne vessel in Indian ocean in 2009. ozonesonde measurements at Kerguelen Island (49°S,70°E) from 2008 to 2009. These observations are analysed using FLEXPART dispersion model calculations and allow : - to establish differences in African biomass burning emission GFED2 and GDRIBB inventories. - to evidence an case of inter-hemispheric transport from south east Asia in the upper troposphere in July 2007. - to determinate the composition, expansion and origin of a biomass burning aerosol plume in september 2009 - to highlight the variations of the ozone baseline in the free troposphere at Kerguelen, in link with biomass burning in South Africa and America. Since 2012, a new altitude station is open at the Maido Mount and hosts remote sensing (lidar, spectrometers) and in situ measurements. The Maido observatory will allow to enhance southern hemispheric atmospheric observations in the framework of NDACC and AERONET. It is open to transnational access through the participation to the European project ACTRIS.

EnglishThe Observatory of Atmospheric Physics of La Reunion (OPAR) is a unique observation site through the quality of its infrastructure and instruments, and through its location in an area sparsely documented where physico-chemical processes take place that are essential for the understanding of the climate and improvement in its modelling. In particular, the Maido observatory, inaugurated at the end of 2012, attracts the national and international communities and allows OPAR to enrich its range of instruments and collaborations, and to occupy an important position within research networks and infrastructures. This article presents a brief history of OPAR, some of the scientific topics for which OPAR is of particular interest, the instruments operated, some of scientific results obtained thanks to OPAR observations, as well as its place within the national and international networks. francaisL'Observatoire de physique de l'atmosphere de La Reunion (Opar) est un site d'observation unique par la qualite de son infrastructure et de ses instruments, et par sa localisation dans une zone tres peu documentee et riche de processus physico-chimiques dont l'etude se revele essentielle pour lever certains des verrous actuels portant sur notre comprehension du climat et sa modelisation. En particulier, l'observatoire du Maido, inaugure fin 2012, suscite un engouement important des communautes nationale et internationale ; il permet a l'Opar d'etoffer la richesse de son parc instrumental et de ses collaborations, et d'occuper une place importante dans pres d'une dizaine de reseaux et infrastructures de recherche. Cet article presente un bref historique de la genese de l'Opar, quelques-unes des thematiques scientifiques au regard desquelles il occupe une position privilegiee, les moyens instrumentaux deployes, quelques resultats scientifiques utilisant les donnees generees par l'Opar, ainsi que sa place dans les reseaux nationaux et internationaux.

Communication about Teledetection Appliquee a l'Observation de l'Atmosphere : region tropicale de l'hemisphere sud

Communication about L'OPAR (Observatoire de Physique de l'Atmosphere de la Reunion), un site privilegie pour l'etude de l'atmosphere tropicale : parc instrumental, resultats scientifiques et projets

Communication about Teledetection Appliquee a l'Observation de l'Atmosphere : region tropicale de l'hemisphere sud

Communication about Investigation of temperature trends and gravity wave characteristics from LiDAR profiles recorded at Reunion Island (20.8°S, 55.5°E) from 1994 to 2007