Influence of cloud top properties on liquid water retrievals from MODIS and AMSR- E

Satellite observations in the near Infrared (NIR) and Microwave (MW) are often used to retrieve integrated atmospheric cloud water paths. Comparisons abound, some of them concluding that the NIR returns higher cloud water paths than the MW and others obtaining the opposite result. The NIR cloud water paths from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on AQUA are compared to those from the Advanced Microwave Scanning Radiometer (AMSR-E) to show that the cloud top properties may be used to discriminate cases where the NIR estimates higher cloud water paths than the MW and vice versa. Conflicting results in earlier studies can then be traced back to the filtering criteria used in their comparisons. An analysis is presented for a spatial resolution of 0.25 x 0.25 degree using the equinox and solstice days of 2003-2006. A climatology of cloud water paths, and the relative abundance of ice and liquid phases during these days will be shown. The cloud top pressures and temperatures where MW and NIR differences change sign are presented. Implications for the conclusions of scientific analyses of cloud water paths based on either MODIS or AMSR-E data are discussed.