Climate Change On Typhoon Movement In The Northwestern Pacific And Its Relationship With Large Scale Steering Flow

Using the observational data from the China Meteorological Administration (CMA) and the Shanghai Typhoon Institute (STI) reorganization of the Northwest Pacific typhoon best-track data sets, NECP four-time/day reanalysis data from 1980 to 2009 (the horizontal resolution of 2.5°×2.5°Lat./Lon. grid),and from 2005 to 2009 (the horizontal resolution of 1°×1°Lat./Lon. grid). the typhoon track vocational forecast data in the western North Pacific (South China Sea is included) provided by CMA from 2005 to 2009,Analysis of the features of climate change on typhoon steering flow speed and large-scale in Northwest Pacific, compared difference types of landing typhoon path and the landing of the three stages of the typhoon moving speed, the large-scale steering flow on the impact of typhoon and the past five years Typhoon track forecast error characteristics.The main results are as follow:(1) The Northwest Pacific typhoon average speed is 5.4m/s in 1980-2009 on Aug to Oct, the maximum in June is 6.1 m/s, the minimum in August is 5m/s. The average of the slowest typhoon speed is 4.6m/s in Nineties, and the fastest to 5.6m/s in 80's. internal changes significantly, to 1983 is 6.7m/s, the smallest in 1980 than 4.1m/s to 2.6m/s. Compared to the type of landing typhoon path, landing in Northwest turned to the northeast line of the fastest with an average of 6.8 m/s, the South China Sea inverted parabolic minimum speed, an average of 3.9m/s. Typhoon into the ocean landing, landing three stages during and after landing, the landing during the slowest average speed is 5m/s, the fastest after landing was 6.2m/s. East than the average speed of landing typhoon's moving speed of landing South overheated. (2) The typhoon's moving speed of changes is consistent in the season, internal and interdecadal variations and in large-scale steering flow, and their seasonal and internal time series of the correlation coefficients were 0.98 and 0.93. The average speed of the typhoon steering flow than the speed of large-scale large is 1.3m/s.the numble of left angle sampies is more than right angle samples.the average left angle is,25.2°, the average-right angle is.19.6°.Compared to the type of landing typhoon, typhoon moving speed and the speed difference between the large-scale steering flow is the smallest parabolic down the South China Sea, the average overheated 1.3m/s, the biggest difference is turn the South China Sea northeast of Northwest Bank, the average over 1.6m/s. Smaller differences Than the South East average of landing typhoon. (3) The average forecast errors are 118.9,195.5 and 290.9km of typhoon track forecast from 2005-2009 of CMA for 24,48 and 72h forecast period.The average forecast errors are 71.1,122.6 and 210.6km of typhoon landfall position for 24,48 and 72h forecast period, there are different bias between large scale steering flow and typhoon movement among three typical landfall typhoon tracks and relationships between these bias and 24h typhoon forecast track errors. the largest forecast error of west to northwestward moving typhoon is not corresponding to its smaller bias between steering flow and typhoon movement, which may be related to low skillful forecast of large scale circulation. The forecast error of typhoon landfall in east China is smaller than in south China is consistent with the bias of former between steering flow and typhoon movement being smaller than the later.