摘要:『侵台颱風之GPS 投落送飛機偵察觀測實驗』(追風計畫)使用ASTRA飛機與機載垂直大氣探空系統(AVAPS)設備,以每架次5-6小時時間直接飛到颱風周圍43000英呎的高度投擲投落送,以取得颱風周圍關鍵區域的大氣環境資料:溫度、溼度、氣壓以及風速等,所取得的資料會即時傳送至中央氣象局、NCEP、FNMOC以及JMA,並同化至CWB, NECP(AVN/ GFDL), FNMOC(NOGAPS/ COAMPS/ GFDN), UKMET以及JMA等模式中,以期對於颱風分析與路徑預報上提供可貴的資料;增進對颱風動力,特別是邊界層的了解(Wu et al. 2005, BAMS)。其成果更可作為我國及各國未來擬定飛機觀測策略的重大指標,亦有助於推動策略性颱風觀測(targeted observation)。從2003年至今,追風計畫已針對杜鵑等42個颱風完成55航次之飛機偵察及投落送觀測任務。(今年執行三個颱風,包括米雷、梅花及洛克颱風,共計四次飛行任務),總計在颱風上空飛行291小時、並成功投擲905枚投落送。在觀測的同時,這些寶貴的投落送資料皆即時進入中央氣象局及世界各國氣象單位之電腦預測系統中,協助預測颱風路徑及分析其周圍結構,如暴風半徑及雨帶結構等。由氣象局提供2008年至2011年共四年統計17個颱風27個颱風投落送觀測個案所進行之TWRF(Typhoon Weather Research and Forecasting)颱風預測模式路徑誤差比較圖,可看出這四年加入了追風飛機偵察及投落送觀測資料的數值模擬部份,平均而言使得氣象局TWRF數值模式預報改善7.9 %。因此總體來說,這四年(2008-2011年)颱風飛機偵察及投落送觀測資料對於氣象局的颱風數值模擬部份,有正面的貢獻。另外,追風研究團隊已經發表數十篇與此研究相關之成果論文(計有Wu et al.(2004)、Wu et al.(2005)、Wu et al.(2006)、Wu et al.(2007a,b)、Chou and Wu(2008)、Chen et al.(2009)、Yamaguchi et al.(2009)、Wu et al.(2009a,b,c)、Chou et al.(2010)、Chen et al.(2011)、Chou et al.(2011)、Harnisch et al. (2010)、Huang et al. (2011)、Liang et al. (2011)、Lin et al. (2011)、Weissmann et al.(2011)、Wu et al. (2011a,b)、Yen et al. (2011)、黃,2006、周,2007、廖,2009、連,2009、陳,2009等27篇)。此外,追風科學團隊在2006至2011年中參與國際研討會發表之相關論文,總計有55篇追風計畫相關研究成果論文發表。並於2009年美國氣象學會所發行Monthly Weather Review國際著名學術期刊中發表相關十數篇由主持人所主導並衍生之國際性論文專刊(Special Collection on “Targeted Observations, Data Assimilation, and Tropical Cyclone Predictability”)。總而言之,我們預期在學術界與氣象局的充分合作下,將讓學術界在颱風議題上位於國際研究與作業的前端,颱風之投落送飛機觀測已有具體成果,對於國內及國際皆有相當之貢獻。此委託研究計畫將延續過去追風計畫之成果,持續在投落送颱風觀測、分析及模擬同化的研究上發展,對於颱風資料及颱風模式同化之改進,並協助進行投落送資料分析、影響評估及颱風預報作業上的應用與效益分析。101年度的工作重點將包括:協助進行101年颱風與劇烈天氣個案之投落送觀測,並即時將投落送資料匯入中央氣象局分析及模式系統進行投落送資料分析與對模式模擬同化、預報之影響評估,以及對颱風預報作業上的應用與效益分析評估及研發如何於相關數值模式預報中最有效使用投落送資料
Abstract: In light of the heavy damage done by typhoons to Taiwan year by year, the National Science Council (NSC) of Taiwan places a great premium on typhoon research, and therefore funds the "National Priority Typhoon Research" project for three years (from August 1, 2002 to July 31, 2005), especially including the field experiment, “Dropsonde Observations for Typhoon Surveillance near the Taiwan Region (DOTSTAR)”. The DOTSTAR is an international research program conducted by meteorologists in Taiwan partnered with scientists at the Hurricane Research Division (HRD) and the National Centers for Environmental Prediction (NCEP) of the National Oceanic and Atmospheric Administration (NOAA). This project marks the beginning of a new era for the aircraft surveillance of typhoons 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 43,000 feet in the environment of a tropical cyclone. These sensors gather temperature, humidity, pressure, and wind velocity information as they fall to the surface. Information from the surveillance flights is transmitted in near real-time to the CWB of Taiwan, as well as to the NCEP, FNMOC, and JMA. The data are immediately assimilated into the numerical models of CWB, NCEP (AVN/GFDL), FNMOC (NOGAPS/COAMPS/GFDN), UKMET, 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 data on numerical models, to evaluate the strategies for adaptive/targeted observations, to validate/calibrate the remote-sensing data, and to improve our understanding on the TC dynamics, especially over the TC’s boundary layer (Wu et al. 2005, BAMS).Up to now, 55 missions have been flown for 42 typhoons, with 905 dropwindsondes released. It has been shown that the dropsonde data improve the 12-72-h NCEP GFS track prediction by about 20% (Wu et al. 2007a). In addition, the field experiment, THORPEX/PARC (The Observation System Research and Predictability Experiment Pacific-Asian Regional Campaign, T-PARC), including TCS08 (Tropical Cyclone Structure 2008), TH08 (Typhoon Hunter 2008) and DOTSTAR, has been completed from August to September in 2008. It is believed that the DOTSTAR and T-PARC experiments have made a significant contribution to the international typhoon research community. The project is expected to yield breakthroughs in typhoon research, forecasting, and observation when it is completed. The foci of the new DOTSTAR project in the 2011 year are:Realtime analysis of the DOTSTAR data on CWB WINS systemCollaboration of DOTSTAR with the Central Weather Bureau and other agenciesResearch on the impact of the DOTSTAR data to numerical modelsResearch on the tropical cyclone initialization procedure related to dropwindsondeAnalysis of the methodology of targeted observation