摘要:
ATOVS能接收到穿透台风中心密实云区的微波辐射信息, 利用ATOVS大气参数反演产品分析0414号台风“云娜”的热力结构特征。在准静力平衡假设的前提下, 根据ATOVS对“云娜”台风监测相匹配的4个时次数据, 分别计算出相应的中心海平面最低气压, 同中央气象台利用可见光和红外技术得到的台风报告值相比, 平均偏差为11.8 hPa, 它随时间的变化能显示台风强度演变的过程。
Abstract:
Nowadays, the most widely used tropical cyclone estimation and position analysis techniques employed by operational forecasters are to analyze the infrared and visible satellite imagery. While these products provide invaluable information about the overall structure and strength of tropical cyclones, they often can't penetrate clouds to ascertain low-level storm structures. Relatively, certain waveleng ths of microwave energy are able to penetrate ice clouds (such as the cirrus above the storm). Therefore, it offers a unique perspective into tropical cyclone structures. Advanced TIROS Operational Vertical Sounding (ATOVS) is composed of the Advanced Microwave Sounding Unit (AMSU) and the High-resolution Infrared Radiation Sounder (HIRS/3), which are aboard the NOAA-16-18 satellites. With the International ATOVS Processing Package (IAPP) by Cooperative Institute of Meteorological Satellite Studies (CIMSS) of the University of Wisconsin (UW), the ATOVS data can be finally translated into the retrieval products including the atmospheric temperature profile, moisture profile in both clear and cloudy atmospheres. The domain of typhoon center cloud field is determine according to the coincident infrared image, and then the temperature anomalies are calculate by subtracting the average temperature of outer radius from the temperature at each grid in the domain. By analyzing the cross-section of temperature anomalies, the warm-core of typhoon Rananim can be seen in the upper-troposphere clearly as well as the distribution of strong precipitation in the lower altitude due to its contamination to the upper microwave radiation. But the area range of ATOVS data received by National Satellite Meteo rological Center (NSMC) is not wide enough, which can only receive the data of part of the Western North Pacific besides the mainland. By analyzing the area range of ATOVS retrieval data mapped with the tracks of Rananim from National Meteo rological Center (NMC), four ideal sets of ATOVS retrieval data are recieved. Under hydrostatic assumption, using the nearest NCEP/NCAR reanalyzed data as initial parameter and four sets of ATOVS data mapped with Rananim, the minimum sea level pressure (MSLP) is calculated respectively and compared with the typhoon warning report of NMC estimated from the visible and infrared method, the mean discrepancy of MSLP is found to be 11.8 hPa, showing similar time-variant tendency of Rananim as described by NMC. Therefore, by using ATOVS retrieval products, the thermal structure under the Center Dense Overcast of typhoon Rananim is better displayed; what's more, the relatively accurate intensity of typhoon is obtained when compared with the result of the operational departments.