The effects of vertical wind shear on tropical cyclone(TC) intensity change are examined based on the TC data from the China Meteorological Administration and the NCEP reanalysis daily data from 2001 to 2006.First,the...The effects of vertical wind shear on tropical cyclone(TC) intensity change are examined based on the TC data from the China Meteorological Administration and the NCEP reanalysis daily data from 2001 to 2006.First,the influence of wind shear between different vertical levels and averages in different horizontal areas are compared.The results indicate that the effect of wind shear between 200 and 850 hPa averaged within a 200-800 km annulus on TC intensity change is larger than any other calculated vertical wind shear.High-latitude and intense TCs tend to be less sensitive to the effects of VWS than low-latitude and weak TCs.TCs experience time lags between the imposition of the shear and the weakening in TC intensity.A vertical shear of 8-9 m/s(9-10 m/s) would weaken TC intensity within 60 h(48 h).A vertical shear greater than 10 m/s would weaken TC intensity within 6 h.Finally,a statistical TC intensity prediction scheme is developed by using partial least squares regression,which produces skillful intensity forecasts when potential predictors include factors related to the vertical wind shear.Analysis of the standardized regression coefficients further confirms the obtained statistical results.展开更多
Tropical Rainfall Measuring Mission (TRMM) data [TRMM Microwave Imager/Precipitation Radar/Visible and Infrared Scanner (TMI/PR/VIRS)] and a numerical model are used to investigate the structure and rainfall feature...Tropical Rainfall Measuring Mission (TRMM) data [TRMM Microwave Imager/Precipitation Radar/Visible and Infrared Scanner (TMI/PR/VIRS)] and a numerical model are used to investigate the structure and rainfall features of Tropical Cyclone (TC) Rammasun (2002). Based on the analysis of TRMM data, which are diagnosed together with NCEP/AVN [Aviation (global model)] analysis data, some typical features of TC structure and rainfall are preliminary discovered. Since the limitations of TRMM data are considered for their time resolution and coverage, the world observed by TRMM at sev- eral moments cannot be taken as the representation of the whole period of the TC lifecycle, therefore the picture should be reproduced by a numerical model of high quality. To better understand the structure and rainfall features of TC Rammasun, a numerical simulation is carried out with mesoscale model MM5 in which the validations have been made with the data of TRMM and NCEP/AVN analysis.展开更多
Variations in the initial structure of tropical cyclones(TCs) inevitably affect prediction results;however, the bogus model cannot accurately describe the structure of a weak tropical cyclone with increased initial fi...Variations in the initial structure of tropical cyclones(TCs) inevitably affect prediction results;however, the bogus model cannot accurately describe the structure of a weak tropical cyclone with increased initial field resolution. This study aims to construct a model to improve the prediction of weak TC in southern China. Based on the ECMWF 0.1° analysis data, several vortices were filtered out from tropical depressions and tropical storms in 2018 and 2019 to represent a weak TC reservoir in the South China Sea. For different simulation objects, filtered vortices were combined with the TC environmental field to form ensemble members. The observed TC information was assimilated for simulating TCs Bebinca, Mun, and Ewiniar to verify the feasibility of the proposed model, based on the Global/Regional Assimilation and Prediction Enhanced System(GRAPES) 9-km model developed by the Guangzhou Institute of Tropical and Marine Meteorology. The results show that the initialization scheme of the weak tropical cyclone model improved the intensity prediction of the TC by 26.81%(Bebinca), 18.65%(Mun), and 47.00%(Ewiniar), compared with the control experiment. Because typhoon intensity forecasting has not notably improved for many years, this scheme has certain scientific and operational significance.展开更多
基金National Natural Science Foundation of China(41405060,41475082,41305049,41275067,41475059)
文摘The effects of vertical wind shear on tropical cyclone(TC) intensity change are examined based on the TC data from the China Meteorological Administration and the NCEP reanalysis daily data from 2001 to 2006.First,the influence of wind shear between different vertical levels and averages in different horizontal areas are compared.The results indicate that the effect of wind shear between 200 and 850 hPa averaged within a 200-800 km annulus on TC intensity change is larger than any other calculated vertical wind shear.High-latitude and intense TCs tend to be less sensitive to the effects of VWS than low-latitude and weak TCs.TCs experience time lags between the imposition of the shear and the weakening in TC intensity.A vertical shear of 8-9 m/s(9-10 m/s) would weaken TC intensity within 60 h(48 h).A vertical shear greater than 10 m/s would weaken TC intensity within 6 h.Finally,a statistical TC intensity prediction scheme is developed by using partial least squares regression,which produces skillful intensity forecasts when potential predictors include factors related to the vertical wind shear.Analysis of the standardized regression coefficients further confirms the obtained statistical results.
基金the National Natural Science Foundation of China(Grant Nos.49975014,40275018 , 40333025) National Social Development Research Progrannie granted by TheAfinistry of Science and Technology.
文摘Tropical Rainfall Measuring Mission (TRMM) data [TRMM Microwave Imager/Precipitation Radar/Visible and Infrared Scanner (TMI/PR/VIRS)] and a numerical model are used to investigate the structure and rainfall features of Tropical Cyclone (TC) Rammasun (2002). Based on the analysis of TRMM data, which are diagnosed together with NCEP/AVN [Aviation (global model)] analysis data, some typical features of TC structure and rainfall are preliminary discovered. Since the limitations of TRMM data are considered for their time resolution and coverage, the world observed by TRMM at sev- eral moments cannot be taken as the representation of the whole period of the TC lifecycle, therefore the picture should be reproduced by a numerical model of high quality. To better understand the structure and rainfall features of TC Rammasun, a numerical simulation is carried out with mesoscale model MM5 in which the validations have been made with the data of TRMM and NCEP/AVN analysis.
基金the National Key Research and Development Program of China (2018YFC1507602)Science and Technology Planning Project of Guangdong Province (2017B020244002 and 2018B020208004)+1 种基金Natural Science Foundation of Guangdong Province(2019A1515011118)National Natural Science Foundation of China (41705089)。
文摘Variations in the initial structure of tropical cyclones(TCs) inevitably affect prediction results;however, the bogus model cannot accurately describe the structure of a weak tropical cyclone with increased initial field resolution. This study aims to construct a model to improve the prediction of weak TC in southern China. Based on the ECMWF 0.1° analysis data, several vortices were filtered out from tropical depressions and tropical storms in 2018 and 2019 to represent a weak TC reservoir in the South China Sea. For different simulation objects, filtered vortices were combined with the TC environmental field to form ensemble members. The observed TC information was assimilated for simulating TCs Bebinca, Mun, and Ewiniar to verify the feasibility of the proposed model, based on the Global/Regional Assimilation and Prediction Enhanced System(GRAPES) 9-km model developed by the Guangzhou Institute of Tropical and Marine Meteorology. The results show that the initialization scheme of the weak tropical cyclone model improved the intensity prediction of the TC by 26.81%(Bebinca), 18.65%(Mun), and 47.00%(Ewiniar), compared with the control experiment. Because typhoon intensity forecasting has not notably improved for many years, this scheme has certain scientific and operational significance.
