A Query And Forecast System For Tropical Cyclone Paths Over The Northwest Pacific Ocean Based On GIS

The main work of this thesis is the quick forecast for the track of WNPTC(Tropical Cyclones over Western North Pacific).WNPTC is one of the main disastrous weather systems that can influence the coastal area of southeast China.The quick forecast of the track of WNPTC is significant for Chinese naval ships to avoid typhoon and ensure the safety of navigation.There are various factors that can influence the track of WNPTC.Because the tracks of similar tropical cyclones can reflect the comparability of factors that influence the tracks of tropical cyclones.Consequently,we can utilize the tropical cyclones which were in similar tracks in history to forecast the tracks of tropical cyclones at present.Combined with the spatial similarity theory and spatial analysis function of Arc GIS,we have analyzed historical data of WNPTC since 1949 and data of tracks of the current tropical cyclones for Spatial similarity.The available methods of forecasting the current tracks of tropical cyclones by similar track including the method of adjacent distance extraction,the method of key points of similarity,the method of area index,the Hausdorff distance method,etc.But there are some problems in these methods,such as large amount of calculation,strict conditions of use,difficultly to solve the area,do not apply to the judgment of curve and so on,and it still exists some problems in practical application.In this thesis we introduced Fréchet Distance to measure the spatial similarity of the track of cyclone,but the results of spatial similarity judged by Fréchet Distance are liable influenced greatly by individual abnormal location points on the tracks of tropical cyclones,therefore this thesis has made improvements of it and create a method called "Average shortest distance between the endpoint” which can measure spatial similarity of cyclone's track better.By testing,the system has advantages such as low complexity of calculation time,strong adaptability of environment,flexible and manifold in installment,and in most cases it has good accuracy of forecast.The main tasks of this thesis are as follows:Establish information database of tropical cyclone based on CMA-STI the data set of optimal path of WNPTC released by Shanghai Typhoon Research Institute from the year 1949 to 2014.Combined with the spatial analysis function of Arc GIS,this thesis adopt overlay analysis and buffer analysis for current cyclone' track to search the tracks of typhoons in history and use the method of average shortest distance between the endpoint to calculate the spatial similarity between each historical cyclone and the current cyclone.According to calculating the moving speed and moving direction of each similar cyclone in history and combined with the spatial similarity weights,calculate the site of the current tropical cyclone in the forthcoming 24 hours or 48 hours.At last,the thesis verifies the forecasting outcomes of the current cyclone in the forthcoming 24 hours or 48 hours according to historical data..And the forecasting outcomes indicates the accuracy of forecast can meet the support demand of maritime emergency of meteorology.