Changes In Characteristics Of The Three Different Paths Of Tropical Cyclone

Based on the relevant reference data of the tropical cyclone (TC) in North-westPacific (NWP) Regions from1951to2011,the general climatic features of the TC inNWP, and the monthly mean data from the National Climate Center of China for the59years (1951～2009),the climatic characteristics of the intensity and position of thesubtropical high in the Western Pacific (for short SHWP) at500hPa,the seasonal andinter-annual variations and the relationship with SHWP were analyzed and studied.TheTC intensity,track,the formation regions and their relations were alsoinvestigated．Three familiar kinds of typhoon t racks are sorted based on a set oftyphoon data f rom1951to2011. The result of composite analysis confirms that differenttyphoon t racks correspond to different patterns of the subtropical high in the WesternPacific (SHWP). The spatio-temporal distribution for61years is discussed according tothe new classify method of tropical cyclone in the NWP.The result show that:(1) Thespatio-temporal distribution difference of tropical cyclone in the Northwest Pacific isobvious.There are4sources for the tropical cyclone formation, tropical cyclone activitiesis different in season and position. Tropical cyclones are active from1951to2011andthere are more tropical cyclones in the1960cs, but less from end of1970cs. and most oftropical cyclones occur from June to October in each year.(2) Obviously SHWP has atrend of strengthening and moving westward and northward during the59years. Theperiod intensity index of SHWP exhibits oscillation periods of3～4years and7～8years.3～4years mainly in1980s and1990s. After1978, the inter decadal variation of SHWPshowed that the departures for strength index started to move from being mainly negativeto positive. But the ridge position index had a contrary situation.(3) When the tracks arewestward or northwestward the subtropical high stretches westward, the number of thewestward or northwestward TC is decreased,on the contrary, is increased;when tracks arerecurring ones, the subtropical high stretches westward, the number of the recurring TCis increased,on the contrary, is decreased.The number of TC and SHWP interdecadalchange is analyzed in this study.There is a significant decadal shift in about1970s and1990s. The SHWP has enlagerd,intensified,ande shifted northwestward.This changegives rise to TC.The number of TC was decreased.When the TC formation regions move westward and northward,the TC intensity is lower and the TC tracks movenorth-westward，the number of westward or recurring TCs may be increased.On thecontrary,when the TC formation regions move eastward and southward,the TC intensityis higher and the TC tracks move eastward and southward too,and the number ofnorthwestward TCs may be increased accordingly．...