As an approach to the technological problem that the wind data of QuikSCAT scatterometer cannot accurately describe the zone of typhoon-level strong wind speed, some objective factors such as the typhoon moving speed,...As an approach to the technological problem that the wind data of QuikSCAT scatterometer cannot accurately describe the zone of typhoon-level strong wind speed, some objective factors such as the typhoon moving speed, direction and friction are introduced in this study to construct the asymmetric strengthening of the QuikSCAT wind field. Then by adopting a technology of four-dimensional data assimilation, an experiment that includes both the assimilation and forecasting phases is designed to simulate Typhoon Rananim numerically. The results show that with model constraints and adjustment, this technology can incorporate the QuikSCAT wind data to the entire column of the model atmosphere, improve greatly the simulating effects of the whole-column wind, pressure field and the track as well as the simulated typhoon intensity covered by the forecast phase, and work positively for the forecasting of landfall locations.展开更多
Bemisia tabaci has a wide range of host plants. Due to its short-distance solid migratory ability, there is a phenomenon of migration and damage among plants in different seasons. Through the study of the population g...Bemisia tabaci has a wide range of host plants. Due to its short-distance solid migratory ability, there is a phenomenon of migration and damage among plants in different seasons. Through the study of the population growth and decline rules of B. tabaci on different host plants and the prediction and forecast technology explores its sustainable prevention control technology. This article mainly discusses the research progress of B. tabaci forecasting, realizing the timely prevention and control of B. tabaci and comprehensive regional management, which can effectively reduce the population base of B. tabaci and reduce the number of pesticides used, which has a protective effect on the ecological environment.展开更多
Spatial distribution of rainfall and wind speed forecast errors associated with landfalling tropical cyclones(TC)occur significantly due to incorrect location forecast by numerical models.Two major areas of errors are...Spatial distribution of rainfall and wind speed forecast errors associated with landfalling tropical cyclones(TC)occur significantly due to incorrect location forecast by numerical models.Two major areas of errors are:(i)over-estimation over the model forecast locations and(ii)underestimation over the observed locations of the TCs.A modification method is proposed for real-time improvement of rainfall and wind field forecasts and demonstrated for the typical TC AMPHAN over the Bay of Bengal in 2020.The proposed method to improve the model forecasts is a relocation method through shifting of model forecast locations of TC to the real-time official forecast locations of India Meteorological Department(IMD).The modification is applied to the forecasts obtained from the operational numerical model,the Global Forecast System(GFS)of IMD.Application of the proposed method shows considerable improvement of both the parameters over both the locations.The rainfall forecast errors due to displacement are found to have improved by 44.1%–69.8%and 72.1%–85.2%over the GFS forecast locations and over the observed locations respectively for the respective forecast lead times 48 h,72 h,and 96 h.Similarly,the wind speed forecasts have improved by 27.6%–56.0%and 63.7%–84.6%over the GFS forecast locations and over the observed locations respectively for the respective forecast lead times 60 h,72 h,and 84 h.The results show that the proposed technique has capacity to provide improved spatial distributions of rainfall and wind speed forecasts associated with landfalling TCs and useful guidance to operational forecasters.展开更多
Extreme rainfall is common from May to October in south China.This study investigates the key deviation of initial fields on ensemble forecast of a persistent heavy rainfall event from May 20 to 22,2020 in Guangdong P...Extreme rainfall is common from May to October in south China.This study investigates the key deviation of initial fields on ensemble forecast of a persistent heavy rainfall event from May 20 to 22,2020 in Guangdong Province,south China by comparing ensemble members with different performances.Based on the rainfall distribution and pattern,two types are selected for analysis compared with the observed precipitation.Through the comparison of the thermal and dynamic fields in the middle and lower layers,it can be found that the thermal difference between the middle and lower layers was an important factor which led to the deviation of precipitation distribution.The dynamic factors also have some effects on the precipitation area although they were not as important as the thermal factors in this case.Correlating accumulated precipitation with atmospheric state variables further corroborates the above conclusion.This study suggests that the uncertainty of the thermal and dynamic factors in the numerical model can have a strong impact on the quantitative skills of heavy rainfall forecasts.展开更多
This paper demonstrates a modification method for real-time improvement of wind field forecasts for a typical cyclone VARDAH,which formed over the Bay of Bengal(Bo B)in 2016.The proposed method to improve the wind fie...This paper demonstrates a modification method for real-time improvement of wind field forecasts for a typical cyclone VARDAH,which formed over the Bay of Bengal(Bo B)in 2016.The proposed method to improve the wind field forecasts associated with tropical cyclone consists of two components.The first one is the relocation method,which relocates the wind field forecasts obtained from the Global Forecast System(GFS)data of National Centres for Environmental Prediction(NCEP).The relocation of the model forecasts wind field is made on forecast locations generated by Multi Model Ensemble(MME)track forecast of India Meteorological Department(IMD).The second one is the modification of wind speed,which directly modifies the NCEP GFS wind speed forecasts based on intensity forecasts by Statistical Cyclone Intensity Prediction(SCIP)model of IMD.Applying these two methods,the displacement of wind field and underestimation/overestimation of wind speed in the model forecast field can be improved.Both modification methods show considerable improvements in the displacement and speed of wind field forecasts.The displacement error of wind field is found to have improved by about 51%at 48 h and about 80%at 72 h forecast.Overestimation of maximum wind speed in the forecast field is found to be improved by about 88%at 48 h and about 38%at 72 h forecast.The spatial distributions of corrected wind speed forecasts are also found to be more analogous than direct model forecasts with the corresponding analysis wind at all forecast hours.Two proposed modification methods could provide improved wind field forecast associated with tropical cyclones in real-time.展开更多
基金National Key Fundamental Research and Development Plan of China (2004CB418301)Natural Science Foundation of China (40830958)
文摘As an approach to the technological problem that the wind data of QuikSCAT scatterometer cannot accurately describe the zone of typhoon-level strong wind speed, some objective factors such as the typhoon moving speed, direction and friction are introduced in this study to construct the asymmetric strengthening of the QuikSCAT wind field. Then by adopting a technology of four-dimensional data assimilation, an experiment that includes both the assimilation and forecasting phases is designed to simulate Typhoon Rananim numerically. The results show that with model constraints and adjustment, this technology can incorporate the QuikSCAT wind data to the entire column of the model atmosphere, improve greatly the simulating effects of the whole-column wind, pressure field and the track as well as the simulated typhoon intensity covered by the forecast phase, and work positively for the forecasting of landfall locations.
文摘Bemisia tabaci has a wide range of host plants. Due to its short-distance solid migratory ability, there is a phenomenon of migration and damage among plants in different seasons. Through the study of the population growth and decline rules of B. tabaci on different host plants and the prediction and forecast technology explores its sustainable prevention control technology. This article mainly discusses the research progress of B. tabaci forecasting, realizing the timely prevention and control of B. tabaci and comprehensive regional management, which can effectively reduce the population base of B. tabaci and reduce the number of pesticides used, which has a protective effect on the ecological environment.
文摘Spatial distribution of rainfall and wind speed forecast errors associated with landfalling tropical cyclones(TC)occur significantly due to incorrect location forecast by numerical models.Two major areas of errors are:(i)over-estimation over the model forecast locations and(ii)underestimation over the observed locations of the TCs.A modification method is proposed for real-time improvement of rainfall and wind field forecasts and demonstrated for the typical TC AMPHAN over the Bay of Bengal in 2020.The proposed method to improve the model forecasts is a relocation method through shifting of model forecast locations of TC to the real-time official forecast locations of India Meteorological Department(IMD).The modification is applied to the forecasts obtained from the operational numerical model,the Global Forecast System(GFS)of IMD.Application of the proposed method shows considerable improvement of both the parameters over both the locations.The rainfall forecast errors due to displacement are found to have improved by 44.1%–69.8%and 72.1%–85.2%over the GFS forecast locations and over the observed locations respectively for the respective forecast lead times 48 h,72 h,and 96 h.Similarly,the wind speed forecasts have improved by 27.6%–56.0%and 63.7%–84.6%over the GFS forecast locations and over the observed locations respectively for the respective forecast lead times 60 h,72 h,and 84 h.The results show that the proposed technique has capacity to provide improved spatial distributions of rainfall and wind speed forecasts associated with landfalling TCs and useful guidance to operational forecasters.
基金National Key R&D Program of China(2018YFC1507602)National Natural Science Foundation of China(41975136)+1 种基金Guangdong Basic and Applied Basic Research Foundation(2019A1515011118)Science and Technology Planning Project of Guangdong Province(2017B020244002,2018B020208004)。
文摘Extreme rainfall is common from May to October in south China.This study investigates the key deviation of initial fields on ensemble forecast of a persistent heavy rainfall event from May 20 to 22,2020 in Guangdong Province,south China by comparing ensemble members with different performances.Based on the rainfall distribution and pattern,two types are selected for analysis compared with the observed precipitation.Through the comparison of the thermal and dynamic fields in the middle and lower layers,it can be found that the thermal difference between the middle and lower layers was an important factor which led to the deviation of precipitation distribution.The dynamic factors also have some effects on the precipitation area although they were not as important as the thermal factors in this case.Correlating accumulated precipitation with atmospheric state variables further corroborates the above conclusion.This study suggests that the uncertainty of the thermal and dynamic factors in the numerical model can have a strong impact on the quantitative skills of heavy rainfall forecasts.
文摘This paper demonstrates a modification method for real-time improvement of wind field forecasts for a typical cyclone VARDAH,which formed over the Bay of Bengal(Bo B)in 2016.The proposed method to improve the wind field forecasts associated with tropical cyclone consists of two components.The first one is the relocation method,which relocates the wind field forecasts obtained from the Global Forecast System(GFS)data of National Centres for Environmental Prediction(NCEP).The relocation of the model forecasts wind field is made on forecast locations generated by Multi Model Ensemble(MME)track forecast of India Meteorological Department(IMD).The second one is the modification of wind speed,which directly modifies the NCEP GFS wind speed forecasts based on intensity forecasts by Statistical Cyclone Intensity Prediction(SCIP)model of IMD.Applying these two methods,the displacement of wind field and underestimation/overestimation of wind speed in the model forecast field can be improved.Both modification methods show considerable improvements in the displacement and speed of wind field forecasts.The displacement error of wind field is found to have improved by about 51%at 48 h and about 80%at 72 h forecast.Overestimation of maximum wind speed in the forecast field is found to be improved by about 88%at 48 h and about 38%at 72 h forecast.The spatial distributions of corrected wind speed forecasts are also found to be more analogous than direct model forecasts with the corresponding analysis wind at all forecast hours.Two proposed modification methods could provide improved wind field forecast associated with tropical cyclones in real-time.
