Dust Particle Properties from Airborne HSRL, Ground-based Raman Lidar and in situ Observations

Abstract

The Saharan Mineral Dust Experiment (SAMUM) is an initiative of several German universities and research establishments. Its goal is the characterisation of optical, physical, chemical, and radiative properties of Saharan dust close to a source region (SAMUM Phase 1, Morocco 2006) and in the long-range transport field (SAMUM Phase 2, Cape Verde Islands 2008). SAMUM data may serve as ground truth data to validate satellite products and atmospheric transport models, and to support the EarthCARE mission. The SAMUM Phase 1 intensive field phase was carried out in May/June 2006 in Southern Morocco. Ground sites were Ouarzazate (30.93 deg N, 6.9 deg W), Zagora (30.15 deg N, 5.37 deg W) in Morocco, and Evora (38.53 deg N, 7.90 deg W) in Portugal for long-range transport studies. Two research aircraft were operating from Ouarzazate (Partenavia, local flights) and Casablanca (DLR Falcon), respectively. The DLR Falcon was equipped with an extensive set of aerosol physico-chemical instruments for size, volatility, and absorption measurements, impactor sampling for chemical analyses and with a nadir-looking high spectral resolution lidar (HSRL: aerosol extinction at 532 nm, aerosol backscatter and depolarisation at 532 nm and 1064 nm). The IfT Lidar (aerosol backscatter at 355, 400, 532, 710, 800 and 1064nm, aerosol extinction at 355 and 532nm, and depolarisation at 710 nm) and an AERONET sun photometer were operated at the ground site Ouarzazate south of the Atlas mountains. During the SAMUM Phase 1 intensive period, three large-scale dust events were probed which extended from southern Morocco to Portugal. Vertical (0 - 10 km) and horizontal (Saharan border to southern Portugal) dust plume structures, aerosol optical depth as well as particle microphysical and optical properties were studied for all cases. The upper boundary of the dust layers was found at altitudes between 4 and 6 km above sea level. The internal structure of the dust layers varied from well mixed to stratified. Presented results will cover an intercomparison of aerosol extinction profiles from HSRL, Raman, and in situ data, dust size distributions and dust optical properties particularly at 355 nm, and vertical as well as lateral distributions of aerosol optical properties from HSRL for dust and long-range transport cases. Possible implications for EarthCARE data analysis strategies will be discussed. This work is supported by the Deutsche Forschungsgemeinschaft DFG, the European Space Agency ESA and the European Fleet for Airborne research EUFAR.