New tropical cyclone web page microwave products

Specific updates to the Naval Research Laboratory’s (NRL) tropical cyclone web page will be highlighted in terms of both new remote sensing products and modified graphical user interface (GUI) features. The Marine Meteorology Division has created an Internet web site dedicated to providing a wealth of information specific to any “active” tropical cyclone around the globe. “Active” system information is sent to NRL from the Joint Typhoon Warning Center (JTWC, Pearl Harbor, HI), the National Hurricane Center (Miami, FL) and the Naval Atlantic Meteorology and Oceanography Center (NLMOC, Norfolk, VA). Their combined area of responsibility covers the globe and they create new storms or suspect (invest) areas and modify existing ones by using the Automated Tropical Cyclone Forecasting (ATCF) system. The ATCF database enables the warning centers to rapidly update the TC web page without NRL manual assistance.

The NRL TC web page includes passive microwave imagery products which permit the user to “see through” non-raining clouds and thus greatly enhance our knowledge of storm positions and structure/intensity. Temporal sampling issues have accompanied this unique data set since all these sensors are on polar orbiting platforms and thus view TCs no more than twice/day/satellite. The Special Sensor Microwave/Imager (SSM/I), Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI), Advanced Microwave Sounding Unit (AMSU-B) and the Advanced Microwave Scanning Radiometer (AMSR-E) are being supplemented with the Special Sensor Microwave Imager Sounder (SSMIS) and the Coriolis WindSat polarimetric radiometer.

The WindSat polarimetric radiometer was built as a proof of concept sensor to validate the retrieval of surface wind “vectors” via a passive microwave design instead of the legacy active microwave scatterometers. WindSat includes channels at 7, 11, 19, 24, and 37 GHz over its 1025-km swath with high spatial resolution due to its large 2-meter antenna. Initially, the 37 GHz brightness temperatures will be incorporated into the web page products and supplement existing SSM/I, TMI, and AMSR-E data sets. The 11-km resolution feasible at 37 GHz can be critical in locating TC centers as well as map internal storm structure dynamics vital in estimating intensity. Derived products such as surface wind vectors, sea surface temperature, rain and total columnar water vapor will be added as the calibration and validation program reaches maturity.

The Special Sensor Microwave Imager Sounder (SSMIS) was launched in Oct 2003 (F-16) and is the next generation SSM/I sensor. The SSMIS combines the SSM/I imager channels with the SSM/T1 and T2 sounder channels into one sensor, resulting in improved environmental products. The 19, 22, 37 and 91 GHz channels and 1700-km swath will extend the SSM/I data set (began in 1987) well into the next decade with four more launches on satellites F-(17-20) and provide sorely needed long-term continuity.

These upgrades are being phased into the Navy’s operational TC web page hosted by the Fleet Numerical Meteorology and Oceanography Center (FNMOC), collocated with NRL in Monterey, CA.