87th AMS Annual Meeting

Wednesday, 17 January 2007: 2:30 PM
Lidar based multi-instrument monitoring of variables relevant to the understanding of saharan heat low dynamics during the monsoon onset period in the framework of the African Monsoon Multidisciplinary Analysis project
207B (Henry B. Gonzalez Convention Center)
Juan Cuesta, Laboratoire de Météorologie Dynamique / Institut Pierre-Simon Laplace, Palaiseau, France; and D. Edouart, M. Mimouni, C. N. Flamant, P. H. Flamant, A. Ouladichir, M. Kharef, M. Kharef, M. Zoukani, M. Zoukani, Y. Rouab, Y. Rouab, L. B. Boulkelia, L. Boulkelia, A. Abdouali, M. Salah Ferroudj, A. Bouklila, M. Kadi, B. Ouchène, L. Zeudmi-Sahraoui, A. Saanoune, and J. Pelon
The Saharan heat low (SHL) region is key to understand the West African Monsoon (WAM) dynamics. The presence of the dust layer combined with the high soil temperature which is controlled by the earth's surface heat balance, constitute a unique destabilization factor for the Saharan desert mixed layer. The thermodynamic budget of the thermal low over the Saharan desert is an important element of the climate of the West African region. Also, there is now evidence that the intensity of southerly/southwesterly monsoon flow (including the sudden surge associated with the so called “jump” or onset) is partly controlled by the intensity of the SHL.

In order to improve knowledge of the Saharan heat low dynamics, the Transportable Remote Sensing Station (TReSS) was deployed in Tamanrasset from February to September 2006 under the auspicies of the Office National de la Météorologie Algérienne, Direction Météorologie Région Sud, during the African Monsoon Multidisciplinary Analysis (AMMA) Special Observing Period. TReSS is an autonomous and high-performance system designed to observe radiative and structural properties of clouds and aerosol layers, as well as atmospheric boudary layer (ABL) dynamics. The meteorological station of Tamarasset located in the SHL region and is equipped for monitoring the radiative budget at the surface and microphysical properties of desert dust (at the surface). In addition to being complementary, the Office National de la Météorologie Algérienne and the TReSS measurements are relevant for assessing the diurnal and seasonal evolution of the SHL main characteristics.

This presentation provides an overview of the survey conducted during the WAM onset period of the evolution of key SHL features measured at the Tamanrasset “Supersite”. Comparisons with selected level 1 and level 2 Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (equipped with the nadir pointing backscatter lidar CALIOP) products over the Sahara, will also be discussed.

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