Analysis In Statistical Characteristics Of Tropical Cyclone Motion Velocity Over The Western North Pacific And Its Abnormal Cause

Based on tropical cyclone (TC) best track dataset for western North Pacific in the period of 1970-2009 from national Meteorological Bureau and the Shanghai Typhoon Institute (CMA-STI) and TC track prediction error data during 2005-2010 and horizontal resolution NCEP/NCAR provides for 1°×1° of FNL (Final Operational Analysis) global analysis of information, a percentile method is used to determine the anomaly index of TC moving speed, The temporal and spatial distribution characteristics of anomalous TC movement speed and its change 1 since 1972s in the western North Pacific are analysed, The effect of TC moving speed prediction error on track prediction error and the relationship between large scale steering flow and the error for TC moving speed prediction were studied.Analysis of the large scale circulation features of mobile speed and changes of abnormal TC case were done. The results showed that, (1) the cumulative probability at 95%(5%) quantile thresholds for TC moving speed and its variation of anomaliesl in western North Pacific were 10.8 m s-1 (1.43 m s-1) and 2.42 m s-1 (-1.72 m s-1), respectively; (2)fast-moving or accelerated-moving TC mostly appears in the area of Japan Sea while slow-moving or decelerated-moving TC occurs mainly in the region of South China sea;(3)the seasonal variation of anomalistic-moving TC represents that, the frequency of fast-moving TC is the highest in May and that of slow-moving TC is the highest in October,that of accelerated-moving TC tend to be the highest in June; (4)mobile abnormaly TC is more in 1990’s, and in the 1970’s, TC speed is stable. (5)TC peripheral environment induces a flow of gas is mainly composed of the Western Pacific subtropical high and continental high decision, mobile guiding airflow can be a more accurate description of TC.(6)Nearly 6 years,The TC path prediction error caused by TC movement speed prediction error for the 48.13kmaverage, TC path prediction error caused by TC moving direction prediction error for the average 68.76km, The prediction error of TC moving speed contributed about 41.6% of TC track prediction error on average during 2006-2011;(7) a TC case, which has large track prediction error and more deduced by moving speed prediction error, is studied and shows that the weak large scale environmental steering flow makes TC moves slowly. if the forecasted large scale environmental steering flow be strong, the predicted TC moving speed be faster aster,which may bring large track prediction error.