Applications of AMSR-E measurements for tropical cyclone predictions Part I: Retrieval of Sea Surface Temperature and Wind speed

Abstract  Existing satellite microwave algorithms for retrieving Sea Surface Temperature (SST) and Wind (SSW) are applicable primarily
for non-raining cloudy conditions. With the launch of the Earth Observing System (EOS) Aqua satellite in 2002, the Advanced
Microwave Scanning Radiometer (AMSR-E) onboard provides some unique measurements at lower frequencies which are sensitive
to ocean surface parameters under adverse weather conditions. In this study, a new algorithm is developed to derive SST and
SSW for hurricane predictions such as hurricane vortex analysis from the AMSR-E measurements at 6.925 and 10.65 GHz. In the
algorithm, the effects of precipitation emission and scattering on the measurements are properly taken into account. The algorithm
performances are evaluated with buoy measurements and aircraft dropsonde data. It is found that the root mean square (RMS)
errors for SST and SSW are about 1.8 K and 1.9 m s⁻¹, respectively, when the results are compared with the buoy data over open oceans under precipitating clouds (e.g., its liquid
water path is larger than 0.5 mm), while they are 1.1 K for SST and 2.0 m s⁻¹ for SSW, respectively, when the retrievals are validated against the dropsonde measurements over warm oceans. These results
indicate that our newly developed algorithm can provide some critical surface information for tropical cycle predictions.
Currently, this newly developed algorithm has been implemented into the hybrid variational scheme for the hurricane vortex
analysis to provide predictions of SST and SSW fields.