西北太平洋熱帶氣旋移動路徑的年際變化及其機理研究

1、西北太平洋熱帶氣旋移動路徑的年際變化及其機理研究黃榮輝陳光華中國科學(xué)院大氣物理研究所季風(fēng)系統(tǒng)研究中心,北京,100080摘要利用JTWC的熱帶氣旋資料、NCEP/NCAR再分析的風(fēng)場資料以及Scripps海洋研究所的海溫資料分析了西北太平洋熱帶氣旋(TC移動路徑的年際變化及其機理。結(jié)果表明,西北太平洋TC移動路徑有明顯的年際變化并與西太平洋暖池?zé)釥顟B(tài)有很密切的關(guān)系。當(dāng)西太平洋暖池處于暖狀態(tài),西北太平洋上空TC移動路徑偏西,影響中國的臺風(fēng)個數(shù)偏多;相反,當(dāng)西太平洋暖池處于冷狀態(tài),西北太平洋的TC移動路徑偏東,影響日本的臺風(fēng)個數(shù)偏多,而影響中國的臺風(fēng)個數(shù)可能偏少。本研究以西太平洋暖池處于冷狀態(tài)的2

2、004年與西太平洋暖池處于暖狀態(tài)的2006年的西北太平洋TC移動路徑的差別進一步論證了這一分析結(jié)果并從動力理論方面分析了在西太平洋暖池不同熱狀態(tài)下,季風(fēng)槽對赤道西傳天氣尺度的Rossby重力混合波轉(zhuǎn)變成熱帶低壓型波動(TD型波動的影響,以此揭示西太平洋暖池的熱狀態(tài)對西北太平洋TC生成位置與移動路徑年際變化的影響機理。分析結(jié)果表明,當(dāng)西北太平洋暖池處于暖狀態(tài)時,季風(fēng)槽偏西,使得熱帶太平洋上空對流層低層Rossby重力混合波轉(zhuǎn)變成TD 型波動的位置也偏西,從而造成TC生成平均位置偏西,并易于出現(xiàn)西行路徑;相反,當(dāng)西太平洋暖池處于冷狀態(tài)時,季風(fēng)槽偏東,這造成了對流層低層Rossby重力混合波轉(zhuǎn)變成T

3、D 型波動的區(qū)域,以及TC生成的平均位置都偏東,從而導(dǎo)致TC移動路徑以東北轉(zhuǎn)向為主。關(guān)鍵詞:熱帶氣旋,臺風(fēng),移動路徑,年際變化,西太平洋暖池。初稿時間:2007年6月17日;修改稿時間:2007年8月16日。資助項目:國家“973計劃”項目(2006CB403601、國家海洋專項(908-02-01-02和國家重大支撐項目“重大海洋災(zāi)害預(yù)警及應(yīng)急技術(shù)研究”第3課題(2006BAC03B03。作者簡介:黃榮輝,主要從事行星波動力學(xué)、大氣環(huán)流理論和熱帶海-氣相互作用及對季風(fēng)、臺風(fēng)影響研究。Email:hrhRESEARCH ON INTERANNUAL VARIATIONS OF TRACKS O

4、F TROPICAL CYCLONESOVER NORTHWEST PACIFIC AND THEIR PHYSICAL MECHANISMHuang Ronghui Chen GuanghuaCenter for Monsoon System Research, Institute of Atmospheric Physics,Chinese Academy of Sciences, Beijing 100080AbstractInterannual variations of moving tracks of tropical cyclones (TCs over the Northwes

5、t Pacific during the period of 1959-2003 and their physical mechanism are analyzed by using the typhoon data provided by JTWC, the wind field data from the NCEP/NCAR reanalysis dataset, and the sea temperature data provided by the Scripps Oceanographic Institute, U.S.A. Analysis results show that in

6、terannual variations of the cyclogenesis and track of TCs over the Northwest Pacific are very obvious and closely associated with the thermal states of the Western Pacific, especially with the subsurface sea temperature of Western Pacific warm pool. When the Western Pacific warm pool is in a warm st

7、ate, then the moving tracks of TCs will shift westward over the Northwest Pacific, thus, the number of typhoons influencing China may be above normal. On the contrary, when the Western Pacific warm pool is in a cold state, then the moving tracks of TCs will shift eastward, thus, the number of typhoo

8、nsinfluencing Japan may be above normal, but the number of typhoons influencing China may be below normal. This analysis result is further demonstrated with the difference between the moving tracks of TCs over the Northwest Pacific in 2004 when the warm pool was in the cold state and in 2006 when th

9、e warm pool was in the warm state. Moreover, the physical mechanism of the impact of the thermal states of the Western Pacific warm pool on the moving tracks of TCs over the Northwest Pacific is revealed by the dynamical analysis of the influence of the thermal state of the warm pool on the monsoon

10、trough position and the transformation from the mixed Rossby gravity wave to the tropical depression type disturbance, i.e., the TD type disturbance over the tropical Pacific. When the Western Pacific is in a warm state, then the monsoon trough shifts westward, thus, the convergent region of zonal w

11、ind field in the southern part of the monsoon trough also shifts westward over the Northwest Pacific. Therefore, in this case, the region of the transformation from the mixed Rossby gravity wave to the TD type disturbance also shifts westward, which leads to the westward shift of TCs geneses and the

12、ir moving tracks. On the contrary, when the Western Pacific is in a cold state, then the monsoon trough shifts eastward, thus, the convergent region of zonal wind field in the southern part of the monsoon trough also shifts eastward over the Northwest Pacific. Therefore, in this case, the region of the transformation from the mixed Rossby gravity wave to the TD type disturbance also shifts eastward, whi