Aerosol impact on cloud water path

This presentation focuses on the relationship between satellites retrieved Aerosol Optical Depth (AOD) and Cloud Liquid Water Path (CWP).This study is part of Aerosols and Climate System Interaction project that is being by NOAA. The data set includes Moderate Imaging Spectroradiometer (MODIS) Collection 5 Level 2 joint atmospheric product from the summers of 2006& 2007, in 10 × 10 degree area on the United State East coast.

The sun and satellite angles were restricted to the narrowest range to reduce satellite retrieval biases and the data were screened for cloud top temperature above 265 K to ensure that water clouds were analyzed. The data was sorted into aerosol bins, and the average of CWP calculated for each bin. As the aerosol loading increases, the average CWP shows an initial sharp increase followed by a relatively moderate decrease. In order to eliminate any possible influence from the precipitation history of the study area, data collected on rainy days were removed and the same restrictions were applied to the remaining data. No significant change was observed. The study area precipitation history did not affect the results.

At this time it cannot be determined whether the aerosol is affecting the clouds, or the clouds affecting the aerosol, or a combination of both. Future work will include the effects of water vapor to try to separate the mutual influences of Aerosol, Cloud Liquid Water and Water Vapor.