Differences in SFMR Measurements Alan S. Goldstein, NOAA/Aircraft Operations Center Lt. Col. Jonathan Talbot, USAFR AFRC 53 WRS Dr. Eric Uhlhorn, NOAA/Hurricane Research Division Dr. Ivan Popstefanjia, ProSensing, Inc. Alan S. Goldstein, NOAA/Aircraft Operations Center Lt. Col. Jonathan Talbot, USAFR AFRC 53 WRS Dr. Eric Uhlhorn, NOAA/Hurricane Research Division Dr. Ivan Popstefanjia, ProSensing, Inc.

Stepped Frequency Microwave Radiometer Same Model used on both AOC and 53 rd WRS aircraft

System Block Diagrams Radiometer Conv to Tb, filter, calc WS/RR Raw Counts PS Processor 10 Sec filter, HDOB Message ARWO Computer SFWS/RR Radiometer Conv to Tb, filter, calc WS/RR Raw Counts PS Processor Conv to Tb, filter, calc WS/RR 10 Sec filter, HDOB Message RAMS Computer SFWS/RR Archive Raw Counts Air Force C-130J NOAA P-3

Basic SFMR Theory

Potential Sources of Differences Physical Mount Calibration Accuracy Auxiliary Inputs (SST, Land Map) External Interference Filters and Thresholds Physical Mount Calibration Accuracy Auxiliary Inputs (SST, Land Map) External Interference Filters and Thresholds

Physical Mount Current P-3 mount has 2-1/2” inset Antenna pattern modified by inset walls Radiometer measurements contaminated by temperature of paint on pylon inset Current P-3 mount has 2-1/2” inset Antenna pattern modified by inset walls Radiometer measurements contaminated by temperature of paint on pylon inset

Mount Modification Extend antenna horn to be flush with bottom of pylon

Calibration Annual Ground/Factory Calibration Pre-Season Zero Wind/Zero Rain Cal Flight Ad hoc monitoring Troubleshooting Need to look into trend analysis and cal-of- opportunity JHT investigating continuous cal technique Annual Ground/Factory Calibration Pre-Season Zero Wind/Zero Rain Cal Flight Ad hoc monitoring Troubleshooting Need to look into trend analysis and cal-of- opportunity JHT investigating continuous cal technique

Auxiliary Inputs SST files are updated regularly, but may miss acute changes Landmaps are different, AOC more conservative SST files are updated regularly, but may miss acute changes Landmaps are different, AOC more conservative Cold wake from H. Ida

External Interference To date, exclusively a P-3 problem Worst offender is C-Band Scatterometer Losing two channels reduces filter effectiveness, increases noise (variability) in output products To date, exclusively a P-3 problem Worst offender is C-Band Scatterometer Losing two channels reduces filter effectiveness, increases noise (variability) in output products

Filters and Thresholds AOC uses pre-algorithm linear fit filter Can be used with less than 6 Freq Less accurate at high-WS, high-RR due to real non- linearity in data ProSensing uses post-algorithm worst RMS freq Currently requires 5-6 freq Generally better, but only if interim solution is reasonable Neither filter accounts for 3 sec measurement cycle – affects performance in high dynamic events Two systems also have some differences in threshold criteria, handling of aircraft roll, and N-R loop initialization AOC uses pre-algorithm linear fit filter Can be used with less than 6 Freq Less accurate at high-WS, high-RR due to real non- linearity in data ProSensing uses post-algorithm worst RMS freq Currently requires 5-6 freq Generally better, but only if interim solution is reasonable Neither filter accounts for 3 sec measurement cycle – affects performance in high dynamic events Two systems also have some differences in threshold criteria, handling of aircraft roll, and N-R loop initialization

Case Data – High WS

Case Data – Low WS Improved PS performance with 12/09 software update

Next Steps Fabricate and install antenna horn extensions Reconcile differences in aircraft roll handling and other periphery code Work to create a common set of filters and freq selectors Improve calibration techniques, preferably in conjunction with JHT effort Continue to compare AOC and 53 rd WRS data sets Fabricate and install antenna horn extensions Reconcile differences in aircraft roll handling and other periphery code Work to create a common set of filters and freq selectors Improve calibration techniques, preferably in conjunction with JHT effort Continue to compare AOC and 53 rd WRS data sets