Passive Microwave (AMSR-E) Observations of Hurricane Bill

In a previous post featuring CloudSat observations of Hurricane Bill, the southern side of the storm appears to have colder cloud tops and a more uniform appearance than the northern half of the cyclone.  However, CloudSat radar reflectivity suggested that clouds observed on the southern side of the storm were thick, midlevel ice clouds with scattered, low topped convection underneath.  This demonstrates the value of the two-dimensional (X,Z) radar profiles in characterizing precipitation structures “underneath” more traditional satellite observations.  The northern side of the storm is less uniform in infrared appearance, but CloudSat detected active, deep convection along the majority of the flight track.

The infrared image can be supplemented by 89 GHz, passive microwave brightness temperatures from the AMSR-E instrument aboard Aqua.  These brightness temperatures are obtained simultaneously with infrared brightness temperatures from MODIS.  The passive microwave brightness temperatures are sensitive to the precipitation mass (ice) within the vertical column, and clearly depict the structure of the hurricane eye wall and outer rain bands.

Passive microwave brightness temperatures (89 GHz) from the AMSR-E instrument aboard Aqua, observing Hurricane Bill on August 19, 2009. The flight track of CloudSat and 94 GHz Cloud Profiling Radar reflectivity are provided in a cross section below.

The SPoRT program provides AMSR-E brightness temperatures to partners in the National Weather Service for a variety of applications, including offshore rain rates, convective percentages, and soil moisture.  Images courtesy of the Naval Research Laboratory and the CloudSat Data Processing Center.

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