Summary:
The Stepped-Frequency Microwave Radiometer (SFMR) is an instrument flown on the NOAA and Air Force Hurricane Hunter aircraft that measures surface wind speed and how much rain is falling over the ocean in tropical cyclones. Historically, the SFMR measurements have only been used when the aircraft is not turning or going up or down (i.e., flying straight and level). In order to be able to get measurements when the aircraft is not flying straight and level, we studied how the SFMR measurements change when the aircraft turns side-to-side (i.e., rolls). The data were collected in several tropical cyclones as well as during the NOAA Ocean Winds Winter Experiment in high wind conditions.
Important Conclusions:
- SFMR measurements change with wind direction at high wind speeds when the aircraft is not flying straight and level.
- The direction that the ocean surface waves are moving may also impact the data, but less than wind direction.
- More data are needed to fully understand how wind and wave directions affect the accuracy of measurements from the SFMR.
Read the paper online at https://journals.ametsoc.org/doi/abs/10.1175/JTECH-D-18-0005.1