Department of Atmospheric Sciences, National Taiwan University
After a brief introduction on our recent work related to typhoon dynamics, we put major emphasis on the issues of typhoon-ocean-biogeochemistry interactions based on the synergy of the analyses from the advanced multiple remote sensing (in collaboration with I-I Lin of NCOR in Taiwan and Tim Liu of JPL, NASA) and some simple models. A striking event of the typhoon-induced oceanic bio-response (ocean blooming) and primary production is documented, inferring the potentially important role for typhoons in the local and possibly global carbon cycle; some cases of typhoon-induced SST cooling and wind modulation, and its potential impact on climate is also presented. Then, the rapid intensification of Supertypoon Maemi (2003) and its interaction with an oceanic warm eddy are discussed. It is shown that the warm ocean eddy may play a more important role in sustaining Maemi than in its rapid intensification.
In the end we provide an overview of a field program -- the DOTSTAR (Dropsonde Observations for Typhoon Surveillance near the TAiwan Region), which marks the beginning of a new era for the aircraft surveillance of tropical cyclones (TC) in the western North Pacific. Built upon work pioneered at NOAA's Hurricane Research Division (HRD), the key to the project is the use of airborne sensors -- dropwindsondes, which are released from jet aircraft flying above 42,000 feet in the environment of a tropical cyclone. Information from the surveillance flights is transmitted in near real- time to the Central Weather Bureau (CWB) of Taiwan, as well as the NCEP, FNMOC, and JMA. The data are immediately assimilated into the numerical models of CWB, NCEP (AVN/GFDL), FNMOC (NOGAPS/COAMPS/GFDN), and JMA. The DOTSTAR are expected to provide valuable data which can help increase the accuracy of TC analysis and track forecasts, to assess the impact of the dropsonde data on numerical models, to evaluate the strategies for adaptive observations, to validate/calibrate the remote-sensing data, and to improve our understanding on the TC dynamics, especially over the TC's boundary layer.
On September 1, 2003, the first DOTSTAR mission was successfully completed around Typhoon Dujuan. On November 2, the second mission was launched while the aircraft flew over the center of Typhoon Melor. The preliminary results from the first two missions, and the overall planning and goals of DOTSTAR will be shown. Information on DOTSTAR is available at http://typhoon.as.ntu.edu.tw/DOTSTAR.htm.