Character istic Quantities of C losed Pressure System Centers D istribution and Its Application

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1 316 Vol. 31 No Journal of Nanjing Institute of Meteorology Dec. 2008,,,. [ J ]., 2008, 31 (6) : ,,,, (, ) : P () C ( ), gc3 : 1) r, C gc ( C ),; 2),, ; 3), gc, hpa, r, : ; ; ; ; : P434 : A : (2008) Character istic Quantities of C losed Pressure System Centers D istribution and Its Application WANG Pan2xing, CHEN Yan2cong, LU Chu2han,WANG Rui, L IU Q ing2qing ( School of A tmospheric Sciences, NU IST, Nanjing , China) Abstract:B y using the multi2year series of the circulation indices P ( intensity) and C ( center location) for the closed p ressure system on the unit radius spherical surface, three characteristic quantities of annual system centers( around the climatological center gc) are defined. 1) Average distance r, which is defined as the weighted geometric average distance of the annual system centers C deviating from the climatological center gc ( i. e. the center location anomaly C ), is a measurement for distribution area of the system cen2 ters. 2) Comp ression coefficient, w hich describes the exten t of the annual system cen ter d istribu tion ar2 ea deviating from circularity, is a m easurem ent for distribution aniso trop y of the annual system center locations. 3) M axim um anom aly direction, w hich indicates the m ain anom aly direction of system cen2 ters by using the angle that the system center m axim um anom aly deviates from the east direction at gc. The above three quantities of 100 hpa South A sian H igh (SA H ) are calculated in June, July and A ugust from 1948 to 2007, indicating that they can briefly and exactly describe the distribution characteristics of the center location anom alies on the sp herical surface. A ccord ing to the definitions of r, and, they are also su itable for describing accurately the d istribu tion characteristics of closed system s centers in the other m eteoro log ical elem ent fields on the spherical surface. Key words: closed p ressure system; characteristic quantities of centers distribution; average distance; com2 p ression coefficient; m axim um anomaly direction : ; : : ( KLME060211) ;( ) : (1943 ),,,,,, wangpx@nuist. edu. cn.

2 6, : 759 0,, 2060, ( ) [ 129 ],, [ ],,[ 16 ] 3(S P C ) ( ) f (), N CEP /N CA R ECMW F [ ], ( ) f 0, S P C, {S ( t) P ( t) C ( t) ; t = 1, T} (1), ( 1) {S ( t) P ( t) ; t = 1, T}, [ 16, 21 ] S P (, )= 2, - 2, { c ( t) c ( t) ; t = 1, T} (, ) [ 16 ], o x y, { c ( t) c ( t) ; t = 1, T}3, 100 hpa 6 7 8, hpa( ), [ 21 ] f 0 = dagpm E N, N C EP /N CA R ( ,== 215 ) S P C 60 a( 1) hpaff f 0, S,f - f 0 P,( 1 ) f f 0 f - f 0 [ 16 ] 2 60 a ; ([ 16 ] ), gc = ( E, N ), ( Pakistan) hpa Table 1 C irculation indices of 100 hpa South A sian H igh (SA H ) in July during t S / rad 2 P / ( dagpm rad 2 ) c / E c / N t S / rad 2 P / ( dagpm rad 2 ) c / E c / N

3 Table 1 ( continued) t S / rad 2 P / ( dagpm rad 2 ) c / E c / N t S / rad 2 P / ( dagpm rad 2 ) c / E c / N S P C ( :; :( f 0 = dagpm ) ; ; 3 km ) Fig. 1 Calculation graph for S, P and C of SA H in July of 1984 ( : SA H center location; thick solid line: rep resentative geopo2 tential height line ( f 0 = dagpm ) ; dash and dot line: boundary line of searching area ; thick broken line: boundary line of the Tibetan Plateau m ain body, w hose altitude is higher than 3 km ) 2 C gc, 3 : 1 ) r, ; 2),; 3),

4 6, : (, ) Fig. 2 D istribution of SAH center locations in July during ( : center location in the past years; : clim atological center) 2, C ( ), C = (, ), [ 0, 2 ),- 2, = 2 2 -, C = (, ), [0, 2 ),[ 0, ] (2) 1, : 1) oxy : [ 16 ] S P C o ; x0 ; y 2 3 ; 2 x y ( -, oxy3( ) 2) o x y : o (, ) ; x +, o () ( ), ( +- ), ; y o x,o, o () (), + 2-2, ( + - ) ;x y ( -, o yx y3 3 oxy o x y(o XYZ ) Fig. 3 Relationship betw een coordinate oxy and o x y on spherical surface ( O XYZ is the 3 D system, w hose origin is at the earthπs core) rectangular coordinate, [ 22 ], 211o ( 0, 0 ) oxy o( 0, 0 ),oxy ( x, y), o x y ( x, y), ox y,x y ( x, y) ooxy ( 4) oxo oyo,

5 o oxy ( x, y) () (O XYZ ) Fig. 4 Coordinates ( x, y) of o on the coordinate oxy ( lo2 cal) (O XYZ is the 3 D rectangular coordinate system, w hose origin is at the earthπs core) x = y = 2, xoo = 0, yoo = 2-0, (3) oo = 0, ( oo ), o x = ox = a rc tan ( tan 0 cos 0 ), y = oy = a rc tan o x = a rcs in ( s in 0 sin 0 ), tan 0 cos 2-0 ; o y = a rcs in s in 0 sin 2-0 ; xo o = a rcco t ( cos 0 tan 0 ), (4) yo o = a rcco t cos 0 tan q (, ) o x y q (, ) o x y ( x, y ) q o y x y x ( y ),q x ( y ),x ( y ) x ( y )q o x y ( 5) ox q, x = /2, x oq = - 0, oq = (5) 5q (, ) o x y ( x, y ) (; O XYZ ) Fig. 5 Coordinates ( x, y ) of q (, ) on the coordinate o x y ( local; OXYZ is the 3 D rectangular coordinate sys2 tem, w hose origin is at the earthπs core) ox = a rc tan [ tan cos ( - 0 ) ], x q = a rcsin [ s in sin ( - 0 ) ] (6) o x q, o x = ox - oo = a rc tan [ tan cos ( - 0 ) ] - 0, o q = a rccos ( cosx qcoso x ), x o q = a rcsin s inx q s ino q o y q, y o q = 2 - x o q, o y = a rc tan ( tano qcos y o q), y q = a rcs in ( sino qs in y o q) qo x y (7) (8) x = o x, y = o y, (9) = x o q,= o q (10) ogc = (73118 E, N ) o x y hpa o x y ( 2), ( 6) gc [ 16 ], o { c ( t) c ( t) ; t = 1, 60} 3 [ 16 ], o x y oxy { c ( t) c ( t) ; t = 1, T},o x y

6 6, : hpa o x y Table 2 Coordinates on the o x y, longitude and colatitude of 100 hpa SAH centers in July during t x c y c c / ( ) c / ( ) t x c y c c / ( ) c / ( ) T w ( t) x c ( t) = 0, t = 1 T w ( t) y c ( t) t = 1, tw ( t) = 0 (11) w ( t) = T P ( t) P ( t) t = 1 (12), 26 Q ( ) = T w ( t) p 2 r ( t) (13) t = 1, p r ( t) tc ( t) d

7 hpax 2y 2( : ; : x ; : y ) Fig. 6 D istribution of 100 hpa SA H centers in July during on the x 2y and 2 coordinate ( : center location in the past years; dash line: x isoline; dash and dot line: y isoline) (,x ) 7, p r ( t) = a rc tan [ tan c ( t) cos ( c ( t) - ) ] (14) Q ( ) Q ( ) Q m ax m ax, Q m in m in Q ( ),0, 2 ) Q m ax, m ax1 m ax2 ; Q m in, m in1 m in2 ; m ax m in ( ) [ 0, 2 Q m ax Q m in m ax m in, { P ( t) ( t) ( t) ; t = 1, T} ; Q m ax Q m in m ax m in 7 o x y C ( t)d ( ) p r Fig. 7 Schem atic diagram of p r that is the p rojection of system center C ( t) at the undeterm ined direction d ( ) on the coordinate o x y in a certain year

8 6, : 765, Q m ax Q m in a b, a = Q 1 2 m ax, (15) b = Q 1 2 m in a b m ax m in gc,, a b m ax 1) r r = (Q m ax + Q m in ) 1 2 (16) gc, C ( t), r, 2) = b (17) a,,, 3) = m ax - (18) 2 gc ( o x y),, [ - /2, /2) ]> 0, ; < 0, ; = 0, 4,, [ 16 ] { P ( t) ( t) ( t) ; t = 1, T} gc, C gc,, hpa, Q m ax = , Q m in = , m ax = 8712, m in = 17712, a = = 2197, b = = 1133, r = = 3126, = b a = 0145, = = [ 21 ] ( 6 8 ) 100 hpa P C, gc r ( 3), 100 hpa hpa Table 3 Characteristic quantities of 100 hpa SA H centers in June, July and A ugust during gc = (, g ) r / ( ) / ( ) (8015 E, 2817 N ) (7312 E, 3416 N ) (7619 E, 3319 N ) [ 16 ] P () C ( ), gc 3 : 1) r, C gc ( C ),; 2 ),, ; 3), gc, hpa, r, : [ 1 ]. [ J ]., 1962, 31 (4) : [ 2 ],. [ J ]., 1981, 36 (1) : [ 3 ],,. [ J ]., 1983, 7 (4) : [ 4 ]. [ J ]., 1991, 14 () :

9 [ 5 ],,. 5 [ J ]., 1994, 13 (2) : [ 6 ],,,. [ J ]., 1997, 55 (6) : [ 7 ],,,. [ J ]., 2000, 23 (1) : [ 8 ],,. [ J ]., 2001, 17 (3) : [ 9 ] Q ian W eihong, Zhang Henian, Zhu Yafen. Interannual and inter2 decadal variability of East A sian ACA S and their im pact on tem 2 perature of China in w inter season for the last century [ J ]. A dv A tm os Sci, 2001, 18 (4) : [ 10 ]. [ M ]. :, 1999: [ 11 ],,,. [M ]. :, [ 12 ],,. [ J ]., 2000, 24 (1) : [ 13 ],,. [ J ]., 2005, 25 (5) : [ 14 ],. [ J ]., 2006, 26 (2) : [ 15 ],,,. [ J ]., 2007, 27 (3) : [ 16 ],,,. [ J ]., 2007, 30 (6) : [ 17 ] Kalnay E, Kanam itsu M, Kistler R, et al. The NCEP /NCAR 402 year reanalysis p roject [ J ]. B ull Am er M eteor Soc, 1996, 77 (3) : [ 18 ] Kistler R, Kalnay E, Collins W, et al. The NCEP /NCAR 502year reanalysis: M onthly m eans CD 2ROM and docum entation [ J ]. B ull Am er M eteor Soc, 2001, 82 (2) : [ 19 ] G ibson J K, Kallberg P, Uppala S, et al. ERA descrip tion [ R ] / / ECMW F. Re2A nalysis ( ERA ) Park, Reading: ECMW F, Project Report Series. Shinfield [ 20 ] S imm ons A J, G ibson J K. The ERA 240 p roject p lan [ R ] / / EC2 MW F. ERA 240 Project Report Series. Shinfield Park, Reading: ECMW F, [ 21 ],,,..,. [ 22 ]. [M ]. :, 2005: 52.

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