10 30 IOD [ ], IOD, [ 14 ] El N ino 8,, [ 15 ],, ENSO IOD, IOD N ino GISST2. 3b [ 16 ] CMAP [ 17 ] NCEP / NCAR [

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1 30 1 Vol. 30 No Journal of Nanjing Institute of Meteorology Feb. 2007, (, ) : GISST CMAP, ( IOD ) ENSO, IOD N ino3, 3, : 6 8,, ; 5 60 %,( ) IOD, SS2 TA ( ), ( ), ( ) : ; ; ; : P : A : (2007) Relationships between SSTA of Tropical Indian Ocean and Summer Ra infall in Southern China Q IAN W ei, GUAN Zhao2yong (Jiangsu Key Laboratory of Meteorological D isaster, NU IST, Nanjing , China) Abstract:U sing the monthly mean data from GISST2. 3b dataset and CMAP p recip itation data from 1979 to 1999, the relationship s between trop ical SSTA of Indian Ocean and summer rainfall in southern China have been studied. By defining the pure Indian Ocean D ipole ( IOD) index and pure N ino3 index, the re2 sults demonstrate that both IOD and the trop ical m iddle Indian Ocean SSTA from Jun to August have sig2 nificant positive correlations w ith summ er rainfall in southern China. About 60 % summer rainfall anoma2 lies in southern China can be exp lained by the interannual variations of trop ical Indian Ocean SSTA in May, which is a very useful clue to rainfall p rediction. W hen the IOD index is positive ( negative), summer rainfall increases( reduces) in southern China, due to the anomalous ascent( subsidence) and water vapor convergence ( divergence) caused by trop ical Indian Ocean SSTA. Key words: trop ical Indian Ocean; D ipole SSTA; South China summer rainfall; interannual variation 0,, [ 122 ] 1999 Saji [ 3 ] W ebster [ 4 ], ( E, 10 S 10 N) ( E, 10 S 0 ) ( T SSA ) ( IOD ) IOD, 9 11, 1 4, ENSO [ 526 ] IOD ( ) ( ), ( ) [ 3 ] [ 7210 ] : ; : : (2004CB418302) ; ( ) ; : (19802),,,, :, qianwei2003y@nuist. edu. cn.

2 10 30 IOD [ ], IOD, [ 14 ] El N ino 8,, [ 15 ],, ENSO IOD, IOD N ino GISST2. 3b [ 16 ] CMAP [ 17 ] NCEP / NCAR [ 18 ], 6 8 (JJA ) IOD ENSO,, [ ] : Y ( o ri) = Y ( reg) + Y r : Y ( o ri) Y; Y ( reg) X Y ; Y r, Y X X Y, Y ( reg) = r XY X, r XY X Y ( JJA ) T SSA, Saji [ 3 ], IOD, I IOD, ENSO N ino3, ( W, S 5 N) T SSA, N ino3, I N ino3 I N ino3 I IOD : I IOD = I (N ino3) + I ( P IOD ), I IOD : I N ino3, I (N ino3), I N ino3, IOD, I ( P IOD) (pure IOD index), EN2 SO IOD, N ino3, I ( PN ino3) N ino3 index) : ( pure I N ino3 = I ( IOD ) + I ( PN ino3) I ( P IOD) T SSA, IOD T SSA, ( P IOD) T SSA : T SSA = T SSA, ( P IOD) + T SSA ; I ( PN ino3) T SSA, El N ino La N ina T SSA, ( PN ino3) T SSA, R : T SSA = T SSA, ( PN ino3) + T SSA, R,, T SSA 3 : T SSA = T SSA, ( P IOD) + T SSA, ( PN ino3) + T SSA, R I ( P IOD) = [ 2, 629 ] IOD : ; IOD : Q ian [ 21 ], 0. 5 [ 22 ] N ino3, El N ino ( ) L a N ina ( ) IOD N ino3, T SSA, ( P IOD ) T SSA, ( PN ino3) ( 1) 1a : IOD,, ; IOD 1b EN SO,, IOD N ino IOD ( 2a),, 0. 6 ( ) ( E, N ) ( 2b),,,

1, : 11 1 6 8 IOD T SSA, ( PIOD ) ( a) E l N ino L a N ina T SSA, ( PN ino3) ( b) ( : ; 0. 1 ; ) Fig.

ino m inus L a N ina years ( units: ; all differences are significant at a 0. 1 significance level, w ith positive difference shaded) 2 6 8 IOD ( a) ( b) ( ( ) 0. 1 (0. 05) ) Fig.

3 1, : IOD T SSA, ( PIOD ) ( a) E l N ino L a N ina T SSA, ( PN ino3) ( b) ( : ; 0. 1 ; ) Fig. 1 Com posite m ean differences ( a) of summ er(jja ) trop ical Indian ocean T SSA, ( PIOD ) of positive m inus negative IOD years and ( b) of summ er(jja ) trop ical Pacific T SSA, ( PN ino3) of El N ino m inus L a N ina years ( units: ; all differences are significant at a 0. 1 significance level, w ith positive difference shaded) IOD ( a) ( b) ( ( ) 0. 1 (0. 05) ) Fig. 2 Correlations ( a) betw een the JJA pure IOD index and the JJA rainfall anom alies over China and ( b) betw een summ er rainfall anom alies in southern China and the JJA m ean Indian O cean SSTA (L ight ( darker) grey shaded areas rep resent the correlations passing 0. 1 ( 0. 05) significance level, respectively) , 6 8 IOD ( ), IOD T SSA, ( P IOD ) N ino3 ( ),, ( 0. 1 ), EN SO IOD

12 30 1 6 8 5 Table 1 Correlation coefficients, regression equations and variances of summ er(jja ) /M ay trop ical Indian O cean SSTA indices and the tim e series of summ er rainfall anom alies in

4 Table 1 Correlation coefficients, regression equations and variances of summ er(jja ) /M ay trop ical Indian O cean SSTA indices and the tim e series of summ er rainfall anom alies in southern China / % 6 8 M IO r( x 1 ) ) IOD ( x 2 ) ) ^y 2) M IO ( x 1 ) ) IOD ( x 2 ) ) ^y 2) W IO r( x 1 ) ) = 0. 51x x = 0. 51x x EIO r( x 2 ) ) ^y 2) = 0. 26x x x IOD ( x 3 ) ) W IO ( x 1 ) ) E IO ( x 2 ) ^y 2) = 0. 21x x x IOD ( x 3 ) ) : 1) t ; 2) F. 6 8 T SSA, R ( 3),, ( E, S 4 N ) M IO (M iddle Indian O cean Index) IOD ( 5a, ) : T SSA, R, M IO r; T SSA, M IO T SSA, R ( ( ) 0. 1 (0. 01) ) Fig. 3 Correlations betw een summ er(jja ) anom alies in southern China and JJA T SSA, R rainfall (L ight( darker) grey shaded areas rep resent the correlations passing 0. 1 ( 0. 01) significance level, respectively) 1, M IO r M IO , M IO r M IO ( 4 ),, IOD IOD M IO r ( 5, ) % ; M IO IOD ( 5, ) ( 5, ) % ( 1) 3 SSTA 6 8 SSTA, 5 IOD N ino3 5 IOD ( ), 5 ( ) ( ), ( ) ( ), [ 11 ] 5 T SSA, R ( 6), ( E, 15 S 10 N ) ( E, 5 10 S ) W IO (W estern Indian O cean Index) E IO ( Eastern Indian O cean Index ), T SSA, R W IO r E IO r, T SSA W IO E IO 4

01) significance level, respectively) 6 5 T SSA, R ( ( ) 0. 1 (0. 01) ) Fig.

5 1, : 13 4 M IO r( a) M IO ( b) ( ( ) 0. 1 (0. 01) ) Fig. 4 Correlations betw een ( a)m IO r/ ( b)m IO and the JJA rainfall anom alies in China (L ight( darker) grey shaded areas rep resent the correlations passing 0. 1 ( 0. 01) significance level, respectively) 6 5 T SSA, R ( ( ) 0. 1 (0. 01) ) Fig. 6 Correlations betw een summ er rainfall anom alies in southern China and M ay T SSA, R (L ight( darker) grey shaded areas rep resent the correlations passing 0. 1 ( 0. 01) significance level, respectively) ( 1) : T SSA W IO E IOD % ( 7, ),,, T SSA 3,, (5 ) ( 6 8 ), ( : mm / d) Fig. 5 O bserved summ er p recip itations anom aly series (mm / d) in southern China and its regression fit lines using JJA M IO r and pure IOD index and using M IO and IOD index, respectively, W IO r E IO r W IO E IO ( ),, 5 ( ), ( ) 7 5 ( : mm / d) Fig. 7 O bserved summ er p recip itation anom aly series (mm / d) in southern China, and its linear fit lines by M ay W IO r, EIO r, and pure IOD index and by M ay W IO, EIO, and IOD index, respectively

14 30 4, IOD IOD 850 hpa ( 8a ),, G ill [ 23 ] IOD, 850 hpa ( 8a c), IOD,, [ 24 ] ; IOD,, ( ) IOD, 200 hpa 850 hpa ( 8b d) ( 9), IOD, 850 hpa, 200 hpa,,, IOD,,, ( 1 000 300 hpa ), ( ) IOD ( ) ( 10),

6 , IOD IOD 850 hpa ( 8a ),, G ill [ 23 ] IOD, 850 hpa ( 8a c), IOD,, [ 24 ] ; IOD,, ( ) IOD, 200 hpa 850 hpa ( 8b d) ( 9), IOD, 850 hpa, 200 hpa,,, IOD,,, ( hpa ), ( ) IOD ( ) ( 10), ( ), ( ) IOD, ( ), ( ) ( ), ( ) ( : m 2 / s; : a c m 2 / s; b m 2 / s; d m 2 / s) a. IOD 850 hpa; b. IOD 200 hpa; c. IOD 850 hpa; d IOD 200 hpa Fig. 8 Com posite JJA m eans of anom alous stream functions and rotational w inds ( units: 10 5 m 2 / s; contour interval is m 2 / s in ( a) and ( c), m 2 / s in ( b), and m 2 / s in ( d) ) a. 850 hpa in positive IOD years; b. 200 hpa in positive IOD years; c. 850 hpa in negative IOD years; d. 200 hpa in negative IOD years

1, : 15 9 6 8 850 hpa ( a) 200 hpa ( b) IOD ( : 10 5 m 2 / s; : a 2 10 5 m 2 / s; b 5 10 5 m 2 / s) Fig.

interval is 2 10 5 m 2 / s in ( a) and 5 10 5 m 2 / s in ( b) ) 10 6 8 IOD ( : 10 7 Pa m 2 s - 1 ) Fig.

7 1, : hpa ( a) 200 hpa ( b) IOD ( : 10 5 m 2 / s; : a m 2 / s; b m 2 / s) Fig. 9 Com posite JJA m ean differences of velocity potentials and divergent w inds at ( a) 850 hpa and ( b) 200 hpa for positive m inus negative IOD years ( units: m 2 / s; contour interval is m 2 / s in ( a) and m 2 / s in ( b) ) IOD ( : 10 7 Pa m 2 s - 1 ) Fig. 10 Com posite JJA m ean differences of m oisture velocity potentials for positive m inus negative IOD years ( units: 10 7 Pa m 2 s - 1 ) 5, IOD EN SO, IOD N ino3, SSTA 3 ( T SSA, ( P IOD ) T SSA, ( PN ino3) T SSA, R ), : (1) 6 8 ( ) IOD, ( ) ;, ( ), ( ) [ 8, 11 ] (2) IOD, SSTA ( ) IOD, SSTA ( ), ( ), ( ) (3) 60 % 5 ( 1)

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1, : SVD 59 changes of the vertically integrated diabatic heating, sea level p ressure, and the geopotential height at 500 hpa, the variations of the

1, : SVD 59 changes of the vertically integrated diabatic heating, sea level p ressure, and the geopotential height at 500 hpa, the variations of the 33 1 Vol. 33 No. 1 2010 2 Transactions of A tmospheric Sciences Feb. 2010,,. SVD [ J ]., 2010, 33 (1) : 58266. Zhang Peng2bo, Guan Zhao2yong, Cai Jia2xi. Impacts of interannual variations of Australian