In order to re-examine some trends related to tropical cyclones（TCs） over the western North Pacific since 1949,the unreliable maximum sustained wind(V;) recorded in the 1949-1978 TC best-track data from the Shanghai...In order to re-examine some trends related to tropical cyclones（TCs） over the western North Pacific since 1949,the unreliable maximum sustained wind(V;) recorded in the 1949-1978 TC best-track data from the Shanghai Typhoon Institute was modified based on the wind-pressure relationships（WPRs） in this study. Compared to the WPR scheme based on the cyclostrophic balance,the WPR scheme based on the gradient balance could give a better fit to TCs under higher wind speeds and could introduce smaller estimated errors for TCs locating at higher latitudes as well as TCs landing on the continent.After the V;modification based on minimum sea-level pressure and TC center latitude,the revised annual number of category 4-5 typhoons shows no long-term trend,while the potential destructiveness measured by power-dissipation index decreases slightly,and this trend is not significant in the period 1949-2008.展开更多
The cyclone phase space （CPS） method has been utilized to evaluate the extratropical transition （ET） of tropical cyclones （TCs） in many recent publications. However, these studies mainly focused over the North A...The cyclone phase space （CPS） method has been utilized to evaluate the extratropical transition （ET） of tropical cyclones （TCs） in many recent publications. However, these studies mainly focused over the North Atlantic basin. In this paper, the CPS characteristics of all the cyclones over the western North Pacific are investigated and discussed, with three parameters calculated from the best-track data of the Regional Specialized Meteorological Center in Tokyo and the Japanese 25-yr reanalysis data. It is concluded that most TCs over the western North Pacific possess the non-frontal and warm-core structure, while a larger number of cyclones that have undergone ET hold the frontal and cold-core structure. The spatial pattern of the CPS parameters indicates that the areas of tropical and extratropical cyclone activities could be demarcated by 30 - N. The composite and individual series of three parameters of the CPS indicate that the transformation of –V U T from positive to negative leads to the start of ET, and could be considered as a potential predictor in operationally forecasting an ET event.展开更多
基金National Basic Research Program of China(973 Program, 2009CB421502)the National Natural Science Foundation of China(Grant Nos.40830958,40730948,and 90715031).
文摘In order to re-examine some trends related to tropical cyclones（TCs） over the western North Pacific since 1949,the unreliable maximum sustained wind(V;) recorded in the 1949-1978 TC best-track data from the Shanghai Typhoon Institute was modified based on the wind-pressure relationships（WPRs） in this study. Compared to the WPR scheme based on the cyclostrophic balance,the WPR scheme based on the gradient balance could give a better fit to TCs under higher wind speeds and could introduce smaller estimated errors for TCs locating at higher latitudes as well as TCs landing on the continent.After the V;modification based on minimum sea-level pressure and TC center latitude,the revised annual number of category 4-5 typhoons shows no long-term trend,while the potential destructiveness measured by power-dissipation index decreases slightly,and this trend is not significant in the period 1949-2008.
基金Supported by the National Natural Science Foundation of China under Grant Nos. 40830958 and 40730948the "973" Program of China under Grant No. 2009CB421502the National Rescarch Fund for Public Welfare under Grant Nos. GYHY200906011 and GYHY201006007
文摘The cyclone phase space （CPS） method has been utilized to evaluate the extratropical transition （ET） of tropical cyclones （TCs） in many recent publications. However, these studies mainly focused over the North Atlantic basin. In this paper, the CPS characteristics of all the cyclones over the western North Pacific are investigated and discussed, with three parameters calculated from the best-track data of the Regional Specialized Meteorological Center in Tokyo and the Japanese 25-yr reanalysis data. It is concluded that most TCs over the western North Pacific possess the non-frontal and warm-core structure, while a larger number of cyclones that have undergone ET hold the frontal and cold-core structure. The spatial pattern of the CPS parameters indicates that the areas of tropical and extratropical cyclone activities could be demarcated by 30 - N. The composite and individual series of three parameters of the CPS indicate that the transformation of –V U T from positive to negative leads to the start of ET, and could be considered as a potential predictor in operationally forecasting an ET event.
