Global and regional effects of aerosol optical properties on warm water clouds: Long-term analysis of MODIS data
Abstract
We have analyzed satellite observation data from Terra Moderate Resolution Imaging Spectro-radiometer (MODIS) which provides long-term global cloud and aerosol optical properties. Cloud dataset contains droplet effective radius (EFR), optical thickness (COT), liquid water pass (LWP), cloud top temperature, cloud top height and cloud fraction was retrieved by Comprehensive Analysis Program for Cloud Optical Measurement (CAPCOM) from MODIS-received radiances. Aerosol dataset was derived from MOD04 L2 product. Data from 60°N to 60°S with a resolution of a 0.25° x 0.25° longitude-latitude box were processed everyday from January 1st 2001 to December 31st 2010. Relative humidity (RH), convective available potential energy and some parameters of ECMWF re-analysis data are also used to estimate strength of aerosol-cloud interactions. In our study, correlation between cloud optical properties and column aerosol number concentration (Na) over the ocean shows that 1) correlation slopes between Na and EFR increase with increasing RH, 2) large Na (more than 108.5 particles/cm2) leads to decreased COT under low RH on 850 hPa level and 3) there is no significant correlation between Na and LWP, however, LWP seems to depend on RH. These results indicate that RH strongly affects EFR on the aerosol-cloud interaction process and cloud droplet growth is weaker than evaporation in case of large Na and low RH. We will also discuss seasonal and regional variability of aerosol-cloud interactions with 10-year results. Additionally, we focus on a positive correlation between Na and EFR over a part of land area.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFM.A33C0175S
- Keywords:
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- 3311 ATMOSPHERIC PROCESSES / Clouds and aerosols