Deployment of the UMass Simultaneous Frequency Microwave Radiometer on the NOAA P-3 for the Hurricane Season of 2019

The Stepped Frequency Microwave Radiometer (SFMR) is a key instrument in hurricane reconnaissance and in investigations of tropical cyclones and high-latitude winter storms. It provides estimates of the microwave brightness temperature over a range of C-Band frequencies from which 10 meter ocean-surface wind-speed and column-integrated rain rate are derived. However, recent measurement campaigns of the NOAA Ocean Winds program have found that operational SFMR-derived winds are often inconsistent with other data sources outside the hurricane environment. In addition, the SFMR measurements require 5 to 10 seconds of averaging to cycle through all the frequencies, so measurements through regions of strong wind gradients and/or narrow rain features may be corrupted by this averaging.

The University of Massachusetts Amherst Microwave Remote Sensing Laboratory (MIRSL) developed a specialized version of the SFMR, the UMass Simultaneous Frequency Microwave Radiometer (USFMR) with dual-polarization capabilities that operates six different frequencies in C-Band from 4.6 to 7.1 GHz. Simultaneous measurement eliminates the stepping sequence resulting in a 4-5 fold decrease in the averaging time. Fine time resolution, coupled with an appropriate antenna footprint on the surface could permit resolving fine-scale features such as surface signatures of hurricane boundary layer rolls.

In collaboration with NOAA NESDIS/STAR, the UMass USFMR will be deployed on board of the NOAA P3 aircraft during 2019 hurricane season. Observations by USFMR will be compared to those of the operational SFMR, focusing on observations of the eyewall, with strong wind gradients and narrow rain bands, in order to assess the influence of simultaneous vs sequential sampling in strong gradient regions.