Forecasts of tropical cyclone(TC)tracks from six global models during 2010 and 2012 were assessed to study the current capability of track forecast guidance over the western North Pacific.To measure the performance of...Forecasts of tropical cyclone(TC)tracks from six global models during 2010 and 2012 were assessed to study the current capability of track forecast guidance over the western North Pacific.To measure the performance of the global model forecasts,a series of statistical evaluations of track forecasts up to 120 h were carried out,including the mean,median,percentile distribution,regional distribution,relative position,correlation analysis,and binned analysis.Results showed that certain improvements have been made for the six global models in their prediction accuracy and stability in the past three years.Remarkably,stepped decreases in the values of each quantile were found at all lead time levels from 2010 to 2012 for NCEP-GFS.An analysis of the regional distribution of position errors showed that a high-latitude region,low-latitude region(which covers mostly the TC genesis region)and the South China Sea are the three main areas within which large errors tend to concentrate.The majority of the models show their own respective characteristics of systematic bias at each lead time,as established through the relative position analysis results.Only the results of NCEP-GFS and CMA-T639 did not show any obvious systematic bias in the three-year study period.Binned analyses indicated that the prediction accuracy and stability of most of the models were better for strong TCs than for weak TCs at short lead time levels.It was also found that the models tend to perform better for initially large TCs,or for those with weak vertical wind shear at lead times shorter than 48 h.The results demonstrate the heavy reliance of forecast errors upon the initial characteristics of a TC or its environmental conditions.展开更多
This paper investigates the possible sources of errors associated with tropical cyclone （TC） tracks forecasted using the Global/Regional Assimilation and Prediction System （GRAPES）. The GRAPES forecasts were made ...This paper investigates the possible sources of errors associated with tropical cyclone （TC） tracks forecasted using the Global/Regional Assimilation and Prediction System （GRAPES）. The GRAPES forecasts were made for 16 landfaIling TCs in the western North Pacific basin during the 2008 and 2009 seasons, with a forecast length of 72 hours, and using the default initial conditions （＂initials＂, hereafter）, which are from the NCEP-FNL dataset, as well as ECMWF initials. The forecasts are compared with ECMWF forecasts. The results show that in most TCs, the GRAPES forecasts are improved when using the ECMWF initials compared with the default initials. Compared with the ECMWF initials, the default initials produce lower intensity TCs and a lower intensity subtropical high, but a higher intensity South Asia high and monsoon trough, as well as a higher temperature but lower specific humidity at the TC center. Replacement of the geopotential height and wind fields with the ECMWF initials in and around the TC center at the initial time was found to be the most efficient way to improve the forecasts. In addition, TCs that showed the greatest improvement in forecast accuracy usually had the largest initial uncertainties in TC intensity and were usually in the intensifying phase. The results demonstrate the importance of the initial intensity for TC track forecasts made using GRAPES, and indicate the model is better in describing the intensifying phase than the decaying phase of TCs. Finally, the limit of the improvement indicates that the model error associated with GRAPES forecasts may be the main cause of poor forecasts of landfalling TCs. Thus, further examinations of the model errors are required.展开更多
This work use the global WRF model containing quadruply nesting with which the highest resolution reached 10 km to simulate the typhoons landed on the coast of China in 2011.The model is driven by the reanalysis data ...This work use the global WRF model containing quadruply nesting with which the highest resolution reached 10 km to simulate the typhoons landed on the coast of China in 2011.The model is driven by the reanalysis data fnl with the resolution of 1°x 1°.The study assess the feasibility and applicability of the global WRF model in the 1-7 days prediction of Tropical Cyclone(TC)track by comparing it with the regional WRF model containing the same setting(physical scheme,dynamical frame,model resolution and nesting grid domain).The global model obtain a similar forecast accuracy to the regional model in 1-7 days,with a difference less than 50 km.The forecast accuracy of the global model for 1,2,3,4,5,6 and 7 days is about 70 km,120 km,180 km,240 km,320 km,400 km,and 500 km,respectively.The reason of the significant TC track errors in the forecast more than 3 or 4 days is analyzed,it is due to the poor representation of typhoon and its steering flow under the situation of binary typhoon system.The study show that the global WRF model can be exploited to proceed the high resolution TC simulation and make the TC track forecast up to 7 days but not in the case of multiple typhoon.展开更多
Over the past 25 years, an annual average of 6 to 7 tropical cyclones (TCs) made landfall onChina mainland and Hainan Island with an average intensity of 29.9 m/s at landfall and maintained at leasttropical storm inte...Over the past 25 years, an annual average of 6 to 7 tropical cyclones (TCs) made landfall onChina mainland and Hainan Island with an average intensity of 29.9 m/s at landfall and maintained at leasttropical storm intensity for 15.6 hours over land, leading to 505 deaths and 37 billion yuan in directeconomic loss, which accounted for 0.4% of the annual GDP of China. Although there was little change inthe overall landfall frequency, intensity at landfall and overland duration, the annual total direct economicloss increased significantly due to the rapid economic development over the past 25 years. Under globalwarming, the intensity of TCs that made landfall on Hainan decreased but the overland duration andfrequency of TCs that made landfall on Fujian and Zhejiang increased. At the national and provincial levels,the ratio of the direct economic loss to GDP and casualties caused by landfall tropical cyclones decreased,suggesting the effectiveness of disaster prevention and reduction in China.展开更多
A series of 96-h typhoon track prediction experiments were carried out using medium range forecasting system of NMC by adding BOGUS typhoon (simplified as B-TC) into the first guess field or the analysis field in orde...A series of 96-h typhoon track prediction experiments were carried out using medium range forecasting system of NMC by adding BOGUS typhoon (simplified as B-TC) into the first guess field or the analysis field in order to provide longer time typhoon track forecast. The results show that T106L19 could provide a better forecast to typhoon tracks when the B-TC was added, especially when the typhoon vortex is even weaker. The sensitive experiments on where to add the B-TC show that the results from adding the B-TC into the first guess field are better. The results also show that the initialization smoothes the B-TC a lot and this will affect the typhoon track prediction.展开更多
基金supported by the Projects for Public Welfare(Meteorology)of China(GYHY201006008)National Basic Research Program of China(2009CB421505)+2 种基金the National Natural Science Foundation of China(41275067)the Science and technology Development Project of SMB(QM201202)WMO-TLFDP,the ESCAP/WMO typhoon Committee。
文摘Forecasts of tropical cyclone(TC)tracks from six global models during 2010 and 2012 were assessed to study the current capability of track forecast guidance over the western North Pacific.To measure the performance of the global model forecasts,a series of statistical evaluations of track forecasts up to 120 h were carried out,including the mean,median,percentile distribution,regional distribution,relative position,correlation analysis,and binned analysis.Results showed that certain improvements have been made for the six global models in their prediction accuracy and stability in the past three years.Remarkably,stepped decreases in the values of each quantile were found at all lead time levels from 2010 to 2012 for NCEP-GFS.An analysis of the regional distribution of position errors showed that a high-latitude region,low-latitude region(which covers mostly the TC genesis region)and the South China Sea are the three main areas within which large errors tend to concentrate.The majority of the models show their own respective characteristics of systematic bias at each lead time,as established through the relative position analysis results.Only the results of NCEP-GFS and CMA-T639 did not show any obvious systematic bias in the three-year study period.Binned analyses indicated that the prediction accuracy and stability of most of the models were better for strong TCs than for weak TCs at short lead time levels.It was also found that the models tend to perform better for initially large TCs,or for those with weak vertical wind shear at lead times shorter than 48 h.The results demonstrate the heavy reliance of forecast errors upon the initial characteristics of a TC or its environmental conditions.
基金supported by the National Science and Technology Support Program(Grant.No.2012BAC22B03)the National Natural Science Foundation of China(Grant No.41475100)+1 种基金the Youth Innovation Promotion Association of Chinese Academy of Sciencesthe Japan Society for the Promotion of Science KAKENHI(Grant.No.26282111)
文摘This paper investigates the possible sources of errors associated with tropical cyclone （TC） tracks forecasted using the Global/Regional Assimilation and Prediction System （GRAPES）. The GRAPES forecasts were made for 16 landfaIling TCs in the western North Pacific basin during the 2008 and 2009 seasons, with a forecast length of 72 hours, and using the default initial conditions （＂initials＂, hereafter）, which are from the NCEP-FNL dataset, as well as ECMWF initials. The forecasts are compared with ECMWF forecasts. The results show that in most TCs, the GRAPES forecasts are improved when using the ECMWF initials compared with the default initials. Compared with the ECMWF initials, the default initials produce lower intensity TCs and a lower intensity subtropical high, but a higher intensity South Asia high and monsoon trough, as well as a higher temperature but lower specific humidity at the TC center. Replacement of the geopotential height and wind fields with the ECMWF initials in and around the TC center at the initial time was found to be the most efficient way to improve the forecasts. In addition, TCs that showed the greatest improvement in forecast accuracy usually had the largest initial uncertainties in TC intensity and were usually in the intensifying phase. The results demonstrate the importance of the initial intensity for TC track forecasts made using GRAPES, and indicate the model is better in describing the intensifying phase than the decaying phase of TCs. Finally, the limit of the improvement indicates that the model error associated with GRAPES forecasts may be the main cause of poor forecasts of landfalling TCs. Thus, further examinations of the model errors are required.
基金sponsored by the National Key R&D Program of China(2021YFC3000800)“Research and demonstration application of key physical processes of typhoon variable resolution prediction model”.
文摘This work use the global WRF model containing quadruply nesting with which the highest resolution reached 10 km to simulate the typhoons landed on the coast of China in 2011.The model is driven by the reanalysis data fnl with the resolution of 1°x 1°.The study assess the feasibility and applicability of the global WRF model in the 1-7 days prediction of Tropical Cyclone(TC)track by comparing it with the regional WRF model containing the same setting(physical scheme,dynamical frame,model resolution and nesting grid domain).The global model obtain a similar forecast accuracy to the regional model in 1-7 days,with a difference less than 50 km.The forecast accuracy of the global model for 1,2,3,4,5,6 and 7 days is about 70 km,120 km,180 km,240 km,320 km,400 km,and 500 km,respectively.The reason of the significant TC track errors in the forecast more than 3 or 4 days is analyzed,it is due to the poor representation of typhoon and its steering flow under the situation of binary typhoon system.The study show that the global WRF model can be exploited to proceed the high resolution TC simulation and make the TC track forecast up to 7 days but not in the case of multiple typhoon.
基金National Key Technology Research and Development Program of China(2007BAC29B02)National Basic Research Program of China(2009CB421503)+1 种基金National Natural Science Foundation of China(40875038)Social Commonweal Research Program of the Ministry of Science and Technology of China(GYHY200806009)
文摘Over the past 25 years, an annual average of 6 to 7 tropical cyclones (TCs) made landfall onChina mainland and Hainan Island with an average intensity of 29.9 m/s at landfall and maintained at leasttropical storm intensity for 15.6 hours over land, leading to 505 deaths and 37 billion yuan in directeconomic loss, which accounted for 0.4% of the annual GDP of China. Although there was little change inthe overall landfall frequency, intensity at landfall and overland duration, the annual total direct economicloss increased significantly due to the rapid economic development over the past 25 years. Under globalwarming, the intensity of TCs that made landfall on Hainan decreased but the overland duration andfrequency of TCs that made landfall on Fujian and Zhejiang increased. At the national and provincial levels,the ratio of the direct economic loss to GDP and casualties caused by landfall tropical cyclones decreased,suggesting the effectiveness of disaster prevention and reduction in China.
基金Key scientific research project for the State Meteorological Administration in the 9 five-year development plan (ZX95-01)
文摘A series of 96-h typhoon track prediction experiments were carried out using medium range forecasting system of NMC by adding BOGUS typhoon (simplified as B-TC) into the first guess field or the analysis field in order to provide longer time typhoon track forecast. The results show that T106L19 could provide a better forecast to typhoon tracks when the B-TC was added, especially when the typhoon vortex is even weaker. The sensitive experiments on where to add the B-TC show that the results from adding the B-TC into the first guess field are better. The results also show that the initialization smoothes the B-TC a lot and this will affect the typhoon track prediction.
