of TMI data (5 km at 85 GHz), these fixes are typically assigned very high quality when compared with all other satellite location datasets (e.g., visible, infrared, and microwave sensors such as SSM/I and AMSU-B). Thus, the TMI fixes drive both the near-real-time warning positions and typically the best track created when all data is compiled after a storm has completed its life.

The National Hurricane Center and the Joint Typhoon Warning Center include TMI in their storm discussions that outline how the data have affected their warning positions or provided insight on storm structure that directly influences storm intensity estimates and/or short-term intensity trends. This appendix provides examples of how TMI data are used for intensity estimates and fixing storm locations.

“Now that Kenna [Figure K-1] has developed a vertically deep eye feature in the TRMM data and the center is embedded in the middle of the CDO [Central Dense Overcast] … a 24-hour period of rapid intensification is being forecast.” (From Tropical Storm Kenna Discussion Number 6 at 2 am PDT October 23, 2002.)

Impact of TRMM data: TRMM data led the Tropical Prediction Center to correctly change its forecast from “intensification” to “rapid intensification.”