[2] hPa [8] [9] [10] ( ) [11] [12] 500hPa 2 [13-15] : 500hPa [16] ; NCEP/ [6] NCAR 27 N 2.5

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1 PLATEAU METEOROLOGY Vol.32 No.4 August [J] (4): doi: /j.issn (1. / ; ) : (21 N-39 N95 E-114 E) EOF ; ; : ; ; ; : (2013) doi: /j.issn :P467 :A 1 [3] (21 N-39 N [4] 95 E-114 E) [5] EOF [6] [7] [2] [1] [1] 1958 : ; : : (973 )(2013CB430202); ( ) (GYHY ;GYHY ); 2011 ( )( ) : (1989-). luoxiao11@yeah.net :. lidl@nuist.edu.cn

2 [2] hPa [8] [9] [10] ( ) [11] [12] 500hPa 2 [13-15] : 500hPa [16] ; NCEP/ [6] NCAR 27 N [17] [18] I AR : [19-20] I AR = ( 9+10) 500hPa + ( 9+10). [21] 9 (1) EOF EOF Morlet [23-24] [22] 5-9 [14] 2 t Niuetal [15] : 珚 x 1 - 珚 x 2 t= (2) 7 2 s 槡 1 n 1 n2 [3-4] 21 s= n1s2 1 +n 2s 2 2 [5] 槡 n 1 +n 2-2 ( 3) ν=n 1+n 2-2 t hPa 9-10 ( 1a)

3 4 : (a :mm) (b :%) Fig.1 Distributionsofmulti-annualmeanrainfalfromSeptembertoOctoberinChina(aunit:mm) anditsproportioninannualamount(bunit:%) 3 :(1) 200 mm ;(2) 9-10 ( 2a) 2 20 ;(3) ( 1b) % 24% (2b) 1b 20% (a :d) (b :%) Fig.2 Distributionsofmulti-annualmeanrainfaldayfromSeptembertoOctober inchina(aunit:d)anditsproportioninannualamount(bunit:%)

4 IAR (a ) Morlet (b 95% ) Fig.3 Trendofaverageautumnrainfalindex (IAR)in WestChina(astraightline:Meanvaluesolidline: IARdashedline:Second-orderpolynomialfitingcurve)anditsMorletpowerspectrum analysis(bareawithinthicksolidlinehaspassedtheconfidentlevelof95% lowareabelowpitcharcindicatestheinfluencecone) [5] [3] [4] 2 [2] 4 I AR ; 160 ( 3a) % 2002 I AR ( 4a) Morlet ( 3b) [4] ~8 6

5 4 : (a) (b) 70 (c) 80 (d) 90 (e) (f) Fig.4 SpatialdistributionsofIARin WestChinain (a)1960s(b)1970s(c) 1980s(d)1990s(e)and2000s(f) [25-27] I AR 0.48; I AR b~f I AR 0.48 I AR >0.54 ; I AR > I AR > (I AR > EOF (LV) 52% 0.48) ( 5a) 0.46; 80 I AR > (35.4 N E) (34.2 N108.6 E)

6 EOF Table1 VariancecontributionofthetoptenEOFanalysisloadingvectorsofIARin WestChina EOF LV1 LV2 LV3 LV4 LV5 LV6 LV7 LV8 LV9 LV10 /% /% EOF ( ) (a) (b) (c) (d) (e) (f) Fig.5 TheloadingvectorsofthetopthreemodesofIAR(left)in WestChinaandtheirtimecoeficients (right)from EOFanalysis.(a)(b)thefirstmode(c)(d)thesecondmode(e)(f)thethirdmode

7 4 : 1025 (29.5 N95.5 E) 30 N ( 5f) ( 5b) ( ) ~ E 2 6~8 19~21 4 ( 5c) hPa (30 N) ( 6a) ( 5d)20 ; [21] [18] ( 6a) E32.5 N ; 6 M-K ( 5e) ( 6e) hPa ( 6c) 500hPa hPa ( 6d) 21

1026 32 [4] 9-10 ( ) 200hPa 9-10 6b 9-10 ( 40 m s -1 6e) 35 m s -1 6 9-10 500hPa (a :gpm) 200hPa (b :m s -1 ) 850hPa (c :gpm) 850hPa (d : ) (e :kg m -1 s -1 ) Fig.

8 [4] 9-10 ( ) 200hPa b 9-10 ( 40 m s -1 6e) 35 m s hPa (a :gpm) 200hPa (b :m s -1 ) 850hPa (c :gpm) 850hPa (d : ) (e :kg m -1 s -1 ) Fig.6 Distributionsofmulti-annualmean500hPazonalanomalyfieldofgeopotentialheight(aunit:gpm) 200hPazonalwind (bunit:m s -1 )850hPageopotentialheight(cunit:gpm)850hPa zonalanomalyfieldoftemperature(dunit: )andverticalyintegrated vaporflux (eunit:kg m -1 s -1 )fromseptembertooctober

9 4 : ; 500hPa 5880 gpm ( 7a) 4.2 EOF 700hPa ( ) ( ) 6 ( ) 6 ( ) hPa ( ) 500hPa hpa ( 7a) <-60gpm >30 gpm 200hPa -15gpm ( 7b) 95% 7 EOF 500hPa (a :gpm) 200hPa (b :m s -1 ) ( ) (a) 95% 99% Fig.7 Compositeddiferencesof500hPageopotentialheight(aunit:gpm)and200hPazonalwind (bunit:m s -1 )inthefirsttimemodecoeficientanomalyofiarin WestChinafrom EOFanalysis (highminuslowvalueyears).in (a)thicksolidline:meanvaluein dashedline: Meanvalueinlowvalueyearsoftimecoeficientdash-dotedline:Meanvalueinhigh valueyearsoftimecoeficient.lightanddarkshadedareashavepassed theconfidentlevelsof95% and99%respectively

1028 32 >6m s -1 90 E-100 E >9 m s -1 ( ) >9m s -1 2m s -1 99% 200hPa ( 8b) > -6 10-5 kg m -2 s -1 ( ) 30 N-37.5 N 102.5 E-120 E 99% 9-10 4.3 EOF ( ) ( 32.

10 >6m s E-100 E >9 m s -1 ( ) >9m s -1 2m s -1 99% 200hPa ( 8b) > kg m -2 s -1 ( ) 30 N-37.5 N E-120 E 99% EOF ( ) ( 32.5 N) 6 ( 8a) 105 E ( EOF 32.5 N ( 100 )(a) ( ) ( 10 5 )(b) ( ) 7 Fig.8 Longitude-heightcross-sectionsofstreamlinediferencealong32.5 N (theverticalvelocityisexpanded 100times)(a)andcompositeddiferenceofverticalyintegratedvaporflux (vector)anditsconvergence (dashedlinevalueisexpanded10 5 times)(b)inthefirstmodetimecoeficientanomalyofiar in WestChinafrom EOFanalysis(highmimuslowvalueyears).OthersarethesameasFig.7

4 : 1029 9 EOF 200hPa (a :m s -1 ) 850hPa (b :gpm) ( ) 7 Fig.

EOFanalysis(highminuslowvalueyears).OthersarethesameasFig.

11 4 : EOF 200hPa (a :m s -1 ) 850hPa (b :gpm) ( ) 7 Fig.9 Compositeddiferencesof200hPameridionalwind (aunit:m s -1 )and850hpageopotential height(bunit:gpm)forthesecondmodetimecoeficientanomalyofiarin WestChinafrom EOFanalysis(highminuslowvalueyears).OthersarethesameasFig ) 6 gpm 95% ( ) hpa ( 9a) ; 5880gpm 95% ( 10b) 850hPa ( 9b) > hPa ( 10a) 10 EOF 500hPa (a :gpm) ( ) ( 10 5 )(b) ( ) 7 Fig.10 Compositeddiferencesof500hPageopotentialheight(aunit:gpm)andverticalyintegrated vaporflux (vector)anditsconvergence(dashedlinevalueisexpanded10 5 times)(b)inthe secondmodetimecoeficientanomalyofiarin WestChinafrom EOFanalysis (highminuslowvalueyears).othersarethesameasfig.7

12 (4): > kg m -2 s -1 [3] 500hPa -59. [5] (6): [6] [9] [10] : (1) [12] 193. [13] [14] [J] (1): ~8 (2) [16] [J]. (3) ; [18] [J]. [20] [22] ; : [1]. [J] [2]. [J] (4): [J] (9): [4]. [J] (1):51. [J] [J] (4): [7]. 50 [J] (1): [8]. [M]. : 1991: [J] (2): [J] (3): [11]. [J] (1): [J] (2): culationandsstanomalies[j].advatmossci200825(1): [J] (4):189- [15]NiuNingLiJianping.Interannualvariabilityofautumnpre- cipitationoversouthchinaanditsrelationtoatmosphericcir (4):509- [17] [J] (6): hPa (6): [19]. 40 [J] (1): [J] (3): [21]. [J] (1): [J] (2): [23]. [M]. : 2007: [24]. [M]. : 2005:

13 4 : 1031 [26]ChangC PZhang Y SLiT.Interannualandinterdecadal variationsoftheeastasiansummermonsoonandtropicalpa- [25]. cificssts.parti:rolesofthesubtropicalridge[j].jcli- [J] (3):1-7. mate200013: [27]. [J] (2): NewEvolutionFeaturesofAutumnRainfalin WestChina anditsresponsestoatmosphericcirculation LUO Xiao 1-2 LIDong-liang 1 WANG Hui 1 (1.Nanjng Universityof Information Science & Technology/Key Laboratoryof Meteorological Disasterof Ministryof EducationNanjing210044China; 2.Departmentof AtmosphericScienceNanjing UniversityNanjing210093China) acteristicsintheautumnandtheprolongedandcontinuousrainfalisdetrimentaltocropproduction.the dailyprecipitationdataat166stationin WestChinaduring wasusedtodefineI AR (Indexof autumnrainfal)whichtakesthebothprecipitationandrainydaysintoconsideration.theinterdecadal variationandthetemporalandspatialdistributioncharacteristicsofi AR wasanalysedwitheof & wavelet methodandtheatmosphericcirculationswasalsostudied.theresultsshowthat:thereare maximum Abstract:Theautumnrainfalin WestChina(21 N-39 N95 E-114 E)isoneofthemainclimaticchar- I ARcentersinboththenorthernandsouthernareawithanobviousinterdecadalvariationinitsintensity andrangeduringthelast50years.thenorthernpartofitgetsnorthwardandstrongerandtherangein- creases.themainanomaloustypeofi ARindicatesa northeast-northandwest-southwestreversalpatern anda consisitentpaternonthewhole.whentheaxisoftheclimatologicalsubtropicalwesterlyjetgets strongerandmigrateswestwardthesubtropicalhigh migrateswestwardandnorthwardandindian-my- anmartroughgetsdeeperintheautumnboththeascendingflowsandnorthwardvaportransportation strengthenswhichcontributestothepaternofmorerainfalinthenorthandlessinthesouthwestpart. Keywords:Indexofautumnrainfal;Evolutionfeature;Spatialandtemporaldistributions;Subtropical westerlyjet

NCEP/NCAR [15] 17 ( hPa) u v 1 T h 8 q 12 ( :hpa) ω OLR Fig.1 Distributionofmulti-yearlymeang

NCEP/NCAR [15] 17 ( hPa) u v 1 T h 8 q 12 ( :hpa) ω OLR Fig.1 Distributionofmulti-yearlymeang 303 2011 6 PLATEAU METEOROLOGY Vol.30 No.3 June 2011. [J]. 201130(3): 559-567 1-2 2 2 3 1 (1. 650034;2. 210044;3. 652200) : NCEP/NCAR ( ) 1992 1998 :(1) 1992 ; 1998 1992 (2) OLR 850hPa 200hPa 1992 1998