Wednesday, 25 January 2012
A Satellite Analysis of Aerosol and Cloud Properties Over the Southern Midlatitude Oceans
Room 244 (New Orleans Convention Center )
There is long standing debate as to how to interpret aerosol optical depth (AOD) retrievals in heavy cloud scenes. The "Southern Aerosol Anomaly" is one region that has seen massive divergence in derived AODs. Some scientists suggest this is due to increased sea-salt concentrations caused by the strong near-surface winds of the roaring 40's. Others believe it is associated with cloud halos, aka the so-called “twilight” effect. Finally, some believe these physical rationales are only partially true and the majority of the signal is in fact an artifact of cloud contamination in the retrieval. The resolution of this question has significant implications for a host of climate and aerosol forecast models. In this study, we analyze properties of aerosol particles and clouds to better understand the observed AOD over the high-latitude southern oceans. We examine coincident satellite-derived profiles of aerosol and cloud presence over the region of interest, and corresponding estimates of AOD/cloud optical depth (COD), using observations from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), Moderate Resolution Imaging Spectroradiometer (MODIS), Multi-angle Imaging SpectroRadiometer (MISR) instruments as well as AERONET sun photometers. From this we ascertain realistic uncertainties in retrieved AOD fields from satellite sensors.
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