Physics Instrumentation Center of GPI, Troitsk, Moscow, Russia.
Joint Center for Earth Systems Technology, UMBC, Baltimore, USA
NASA Goddard Space Flight Center, Greenbelt, USA
Jeudi 21 septembre 2017, 09:30, amphithéâtre P. Glorieux (CERLA, bâtiment P5, RDC), Université Lille 1
Synergy of MERRA-2 modeling and Raman lidar measurements for characterization of aerosol properties over West Africa
Observations of multiwavelength Mie-Raman lidar taken during the SHADOW field campaign are used to analyze a smoke/dust episode over West Africa in December 2015. For the case considered, the dust layer extended from the ground up to approximately 2000 m while the elevated smoke layer occurred in the 2500 m – 4000 m range. The profiles of lidar measured backscattering, extinction coefficients and depolarization ratios are compared with the vertical distribution of aerosol parameters provided by the Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2). The MERRA-2 model simulated the correct location of the near–surface dust and elevated smoke layers. The values of modeled and observed extinctions at both 355 nm and 532 nm are also rather close. Good coherence between measured and modeled extinction profiles provides an opportunity to test how well the model reproduces backscattering of dust particles at different wavelengths. The comparison shows good agreement of modeled and measured backscattering coefficients at 355 nm. At 532 nm however, the simulated backscattering coefficients in the dust layer exceed the measurements. This may be an indication that the imaginary part of refractive index used in the model at 532 nm is too low. The model predictions are also used to explain the different features of lidar observations during strong dust episodes.