ATMS Derived Warm Core Evolution of Hurricanes Using a Modified Retrieval Algorithm

The Advanced Technology Microwave Sounder (ATMS) on board Suomi NPP is a cross-track microwave radiometer. Its temperature sounding channels 5-15, which are similar to AMSU-A channels 4-14, are located in an oxygen absorption line near 60 GHz to provide temperature sounding measurements. There measurements represent the total thermal radiative emission from different layers of the atmosphere. In this study, a traditional AMSU-A temperature retrieval algorithm is modified to remove the residual scan biases and upper-level small-scale features in the temperature retrieval. The warm core structures derived for a few selected hurricanes are examined. It is shown that scan biases that are present in the traditional retrieval are adequately removed using the modified algorithm. The hurricane warm core structures in the upper troposphere (~250 hPa) obtained by the modified algorithm are stronger and smoother and those from the traditional retrieval, which are affected by small-scale features from un-correlated low tropospheric channels affected by precipitation. In addition, the warm core structures retrieved with the modified algorithm are compared with MiRS operational outputs.