利用AMSU-B和GOES-9卫星资料对热带气旋“蒲公英”的分析

ANALYSIS OF TROPICAL CYCLONE "MINDULE" USING AMSU-B AND GOES-9 SATELLITE DATA

利用NOAA-16/AMSU-B三水汽通道微波亮温差和GOES-9红外亮温阈值对热带气旋深厚对流云进行检测,同时利用GOES-9可见光、红外、水汽多光谱通道特征对热带气旋云系进行识别,通过一次台风"蒲公英"个例,对热带气旋在微波和光学遥感图像上的深厚对流云进行分析。结果表明,微波和光学遥感资料均能对热带气旋深厚对流云进行有效识别,检测结果基本一致,但识别出的对流云,微波范围较小,光学遥感范围较大,这可能是由于光学遥感仅能获得云顶信息,将对流云顶部覆盖的卷云错判造成的;即使采用较低亮温阈值,光学遥感也很难将这部分卷云完全分离,而微波对云更具穿透性,在深厚对流云的识别方面具有独特优势;三水汽通道间微波亮温差反映了深厚对流云的发展强度,可间接揭示热带气旋的发展情况。

Methods were presented to detect deep convective clouds in the tropical cyclone using NOAA- 16/AMSU-B microwave brightness temperature differences between water vapor channels and GOES-9 infrared brightness thresholds of cloud top temperatures, and the classification of clouds were identified in the tropical cyclone applying with visible/infrared/water vapor spectral features. By analyzing typhoon ＂Mindule＂, the deep convective clouds in the tropical cyclone were investigated. The results show that microwave and optical images could discriminate the deep convective clouds effectively, the detection areas were coincident, while the microwave detection regions were smaller than those of optical detection regions, because the optical remote sensing got the cloud top information only and mistook cirrus clouds overlapping the cumulonimbus as deep convective clouds. Thus, it was difficult to distinguish deep convective clouds and cirrus clouds if only the methods based on infrared temperature thresholds and spectral characteristics were used, and the advantages of microwave remote sensing were shown in the studies on deep convective clouds. The microwave brightness temperature differences between water vapor channels were correlated with the intensity of deep convective clouds, which showed the development of the tropical cyclones indirectly.