396 3 Vol1 3 ent of the baroclinic divergence. The Q TOinduced cyclonic vorticity perturbation leads to eastward extension of the monsoon trough and i

Size: px

Start display at page:

Download "396 3 Vol1 3 ent of the baroclinic divergence. The Q TOinduced cyclonic vorticity perturbation leads to eastward extension of the monsoon trough and i"

蔓玫弓
5 years ago
Views:

1 Vol13 No1 Mar , , 10044, NCEPDO E II, 6,, 10 (Quasi Tenday Oscillation, Q TO), 10, Q TO, Q TO,, Q TO,,,,, Q TO, Q TO, (008) P434 A Dynamical Diagnosis on Possible Formation Cause of Climatological Western Pacif ic Subtropical High Double Ridges Process QI Li 1,, ZHAN G ZuQiang, H E JinHai 1, GUAN ZhaoYong 1, and WAN G LiJ uan 1 1 College of A tmos p heric Sciences, N anj ing Universit y of I nf ormation Science & Technology, N anj ing N ational Climate Center, Bei j ing Abstract NCEPDO E reanalysis II datasets are used to explore the characteristics of the Western Pacific Subtropical High ( WPSH) Double Ridges Process (DRP) f rom the viewpoint of climate mean, and then the possible mechanism for the WPSH DRP is derived on the basis of the interaction between northwestward propagating western Pacific tropical atmospheric Q TO (QuasiTenday Oscillation) and the 810day zonal oscillation of the monsoon trough by use of a twoandahalf layer model. Result s show that the quasitenday westeast oscillation of the monsoon trough over the South China Sea monsoon region is the main cause of the occurrence of climatemean WPSH DRP. Howev er, the zonal movement of the monsoon trough is closely related to the propagation of Q TO. Further studies by vir tue of a twoandahalf layer model indicate that, accompanied with Q TO northwestward propagating, a positive vorticity perturbation characterized by an equivalent barotropic structure is produced at a few latitude degrees north of the Q TOassociated convection center, due to the easterly shear of the mean flow acting on the meridional gradi , , ( ) KL ME06004, 06 KJB170050,, 1981,, : com

2 396 3 Vol1 3 ent of the baroclinic divergence. The Q TOinduced cyclonic vorticity perturbation leads to eastward extension of the monsoon trough and it s consequent intrusion into the WPSH, and thus the formation of double ridges of WPSH. On this account, one of the main causes for the WPSH DRP is possibly Q TO rather than the eastward extension of the monsoon trough because the latter is just the result of the former. Further numerical modeling is required to validate these observational study result s. Key words the Western Pacific Subtropical High ( WPSH) Double Ridges Process (DRP), monsoon trough, Qua sitenday Oscillation (Q TO), twoandahalf layer model 1 ( ) 0 60, [18 ],,,, [91 ] [10 ] : 7 9, [ 1 ] 510 6, 6 10, (QuasiTenday Oscillation, Q TO) (10 E ) 10 Q TO (10 N15 N, 110 E10 E),,, Q TO,?,,, NCEP/ NCAR 0 70, [ 13 ], NCEPDO E II ( ) ( uvw ) ( T), NOAA (OL R) NCEPDO E II, [1 ], (Double Ridges Process, DRP) 500 hpa ( ), 6 ( 1 ) 6,, [1 ], 6 810, Table 1 Climatological Characteristics for the Western Pacif ic Subtropical High ( WPSH) DRPs from May to Oct / d DRP (7 N15 N, 115 E130 E) DRP (5 N1 N, 115 E1 E) DRP (5 N15 N, 115 E17 E) DRP (5 N15 N, 107 E17 E) DRP (5 N1 N, 105 E115 E) DRP (5 N1 N, 105 E1 E)

No1 : Q I Li et al. Dynamical Diagnosis on Possible Formation Cause of Climatological Western Pacific... 397, 810 10 10,, (10 N 15 N, 110 E10 E),, Q TO, 1979005 510 3 ( 3 ), 810, [ 1 ] 3 10 3.

3 No1 : Q I Li et al. Dynamical Diagnosis on Possible Formation Cause of Climatological Western Pacific , ,, (10 N 15 N, 110 E10 E),, Q TO, ( 3 ), 810, [ 1 ] , (0 5 N, 140 E 150 E) 500 hpa 10 (1) ( ISO), 710 [1416 ] Q TO hpa hpa (0 5 N, 140 E150 E) 90 %, Fig. 1 Wavelet power spectrum of 500hPa zonal wind averaged over t he tropical western Pacific ( 0 5 N, 140 E150 E) from May to Oct. Shaded areas are significant at 90 % confidence level. The dashed lines indicate t hecone of influence, where t he edge effects become important ( Extended Empirical Orthogo nal Function, EEOF), Q TO 8, 1, Q TO EEOF %3. 00 %, % %9. 5 %, ( AC ) - 4 (10 N15 N, 110 E 10 E),, 4 Q TO - 4,,, + 4 Q TO - 4, Q TO ( ),, [ 1 ]10 Q TO (10 E ) Q TO, Q TO, Q TO Q TO, ABC Q TO ( AC ), Q TO 0 (110 E 15 E) 3 3, (1. 5 N, 10 E),,, (0 N, 115 E) (500 hpa),, 300 hpa,, ( 1. 5 N, 10 E) 500 hpa,, (15 N ), 15 N

398 3 Vol1 3 Q TO 79 810 500 hpa EEOF 0. 01 m/ s, ABC Q TO Fig. The first EEOF mode of climatemean 500hPa 810day bandpassed zonal wind ( m/ s) during J ulsep for a Q TO period.

4 398 3 Vol1 3 Q TO hpa EEOF m/ s, ABC Q TO Fig. The first EEOF mode of climatemean 500hPa 810day bandpassed zonal wind ( m/ s) during J ulsep for a Q TO period. The absolute values of zonal wind speed in t he shaded areas exceed m/ s. Line ABC is t he propagating direction defined by t he anomaly center moving tracks in different phases 4 10, Q TO? hpa 1. 5 N 4, 6, 10 E, 10 E 4 AB,, EEOF, 10 E15 E,, Q TO, 10 E 15 E Q TO 10 E15 E (5), N0 N, 15 N0 N, - - 1,, 0, (15 N0 N, 10 E15 E), 10 E,, 15 N0 N,,, (15 N0 N, 10 E15 E)

5 No1 : Q I Li et al. Dynamical Diagnosis on Possible Formation Cause of Climatological Western Pacific Q TO 0 AC : (a) ( : m/ s, : ) ; (b) ( : hpa/ s, : ) ; (c) ( : 10-5 s - 1 : ) ; (d) ( : K, : ) Fig. 3 Q TO vertical structure along AC on day 0 : (a) Zonal wind (unit s : m/ s, westerly is shaded) ; ( b) vertical velocity ( unit s : hpa/ s, ascending movement is shaded) ; (c) vorticity (unit s : 10-5 s - 1, positive vorticity is shaded) ; ( d) temperature ( unit s : K, warm areas are shaded), (15 N 0 N, 10 E 15 E) Q TO, E Q TO, 10 N, ;,, 0 N, 400 hpa 18 N ( ), Q TO, Jiang [17 ],, ISO, Q TO (7),, 5/ 5 x = 0, p :

400 3 Vol1 3 5 u 5v + 5gu 5 p - f 0 v = K + f 0 u = - 5v 5 y + 5 5 p = 0 5 T + v 5 gt 5 y 5< 5 y + K u, v, gt +5 5 p - 1 c p= gq c p + K T1 (1) () (3) (4), Q TO ; gu = gu ( p), gv = 0 1 3 (1) (), A +

4 Time evolution of climate mean cyclonic vorticity on a 810 day scale (Q TO) (10-5 s - 1 ) at 500 hpa along the crosssection of AC in Fig. 1. Areas with westerly along 1.

6 400 3 Vol1 3 5 u 5v + 5gu 5 p - f 0 v = K + f 0 u = - 5v 5 y p = 0 5 T + v 5 gt 5 y 5< 5 y + K u, v, gt +5 5 p - 1 c p= gq c p + K T1 (1) () (3) (4), Q TO ; gu = gu ( p), gv = (1) (), A + = A 1 + A, hpa Q TO ( : 10-5 s - 1 ) AC 1. 5 N ( : m/ s) Fig. 4 Time evolution of climate mean cyclonic vorticity on a 810 day scale (Q TO) (10-5 s - 1 ) at 500 hpa along the crosssection of AC in Fig. 1. Areas with westerly along 1. 5 N are shaded 5 10 E15 E ( : 10-5 s - 1 ) : Fig. 5 Timelatitude cross section of Q TO vorticity (10-5 s - 1 ) along 10 E15 E. Positive vorticity is shaded A - = A 1 - A, gut = ( gu1 - gu3 ) /, gut f 0 D- = K 5D + 5D - = 5v 5 x - 5 u 5 y = - 5 u 5 y, D = 5 u 5 x + 5v 5 y = 5v 5 y, 5 5 y ( D + + D - ) + f 0 D + = K - f 0 + = - - f 0 - = - 5 D+ - - gut 5 y, <+ + K <- + K, D+, D-. +, (5) (6) (7) (8),, (5), 5 + gut 5D- 5 y 1 (9), ( ) 8 Q TO ( [ 1 ] 3),,

7 No1 : Q I Li et al. Dynamical Diagnosis on Possible Formation Cause of Climatological Western Pacific E Q TO : (a) ( : hpa/ s, : ) ; (b) ( : m/ s, : ) ; (c) ( : 10-5 s - 1, : ) ; (d) ( : 10-5 s - 1, : ) Fig. 6 Q TO vertical profile along 15 E on day 0 : (a) Vertical velocity (unit s : hpa/ s, ascending movement is shaded) ; (b) zonal wind ( u nit s : m/ s, westerly is shaded) ; (c) vorticity (units : 10-5 s - 1, positive vorticity is shaded) ; (d) divergence (units : 10-5 s - 1, divergence is shaded) 7 Fig. 7 Vertical structure of t he twoandahalf layer model 10 (Q TO) ( 8a), 0, (15 E ) 10 N (6a), ( 8b ) (6d),, (10 N, 15 E) 5D - / 5 y < 0, 5D - / 5 y > 0 (8c) gut = ( gu1 - gu3 ) / < 0 (8d ), (10) (8e f, 6c) 15 E (8g),

8 40 3 Vol1 3 8 Q TO A N V Fig. 8 Schematic diagram for t he interaction between Q TO and t he monsoon trough and formation of WPSH DRP. The letters A, N and V stand for anticyclone, t he nort h and vertical directions, respectively,,,, Q TO, (10 N, 15 E), (8h),

9 No1 : Q I Li et al. Dynamical Diagnosis on Possible Formation Cause of Climatological Western Pacific ,,,,,, Q TO, 10 Q TO,,, Q TO,,,, : Q TO, Q TO,, Q TO, 7 9,, Q TO [18 ],, 5, Q TO,, 10, Q TO 10, Q TO Q TO,,,,,, Q TO,,,,,,,,,, ( References) [ 1 ],,.., 196, 3 (1) : 18 Tao Shiyan, Xu Shuying, Guo Qiyun. Meridional and zonal circulation features over eastern Asian tropical and subtropi cal regions during summer. A cta Meteor. S inica ( in Chi nese), 196, 3 (1) : 18 [ ],,,.. (), 196, () : 4156 Huang Shisong, Tang Mingmin, Huo Yiqiang, et al. Some characteristics and meaning of the progression northward and retrogression southward of t he subtropical high. J. N anjing Universit y (Meteorology) (in Chinese), 196, () : 4156 [ 3 ],.., 196, 31 (4) : Huang Shisong, Yu Zhihao. Structures of subtropical high and associated problems of generation circulation. A cta Mete or. S inica (in Chinese), 196, 31 (4) : [ 4 ] Zhang Peiqun. Dynamical equation and diagnosis of subtropi cal high ridge line movement. Ph. D. dissertation (in Chi nese), Depart ment of At mospheric Sciences, Lanzhou Uni versity, 1997 [ 5 ],,.., 000, 4 (1) : 6778 Zhang Qiong, Qian Yongfu, Zhang Xuehong. Interannual and interdecadal variations of the South Asia high. Chinese J ournal of A tmospheric Sciences ( in Chinese ), 000, 4 (1) : 6778 [ 6 ],,,.. :, pp Wu Guoxiong, Chou Jifan, Liu Yimin, et al. Dy namics of the Formation and V ariation of S ubtropical A nticyclones (in Chinese). Beijing : Science Press, pp [ 7 ],,,.. ( ), 00, 38 (3) : He Jinhai, Wen Min, Shi Xiaohui, et al. Splitting and east

10 404 3 Vol1 3 ward wit hdrawal of the subtropical high belt during the onset of the South China Sea summer monsoon and t heir possible mechanism. J ournal of N anjing University ( Nat ural Sci ences) (in Chinese), 00, 38 (3) : [ 8 ] Lu Riyu. Indices of t he summertime western Nort h Pacific subtropical high. A dv. A tmos. S ci., 00, 19 (6) : [ 9 ],, , 004, 6 (3) : Zhan Ruifen, Li Jianping, He Jinhai. Influence of the double ridges of west Pacific subtropical high of the second Meiyu o ver the Yangtze River valley during A cta Meteor. Sini ca (in Chinese), 004, 6 (3) : [ 10 ],,.., 005, 50 (18) : 006 Zhan Ruifen, Li Jianping, He Jinhai. Climatological charac teristics of t he double ridges of subtropical high in t he Nort h ern Hemisphere. Chinese Science B ulletin ( in Chinese ), 005, 50 (18) : 006 [ 11 ],,,. 196., 006, 30 (4) : 6869 Qi Li, He Jinhai, Zhan Ruifen, et al. Characteristics of t he western Pacific subtropical high double ridges process in 196. Chinese J ournal of A tmospheric Sciences ( in Chi nese), 006, 30 (4) : 6869 [ 1 ],,,. 10., 008, 3 (1) : Qi Li, Guan Zhaoyong, Zhang Zuqiang, et al. Climatological view on double ridges process of the western Pacific subtropi cal high and its relation to quasi10day oscillation of mon soon. Chinese J ournal of A tmospheric Sciences ( in Chi nese), 008, 3 (1) : [ 13 ] Kanamit su M, Ebisuzaki W, Woollen J, et al. NCEPDOE AMIPII reanalysis ( R ). B ull. A mer. Meteor. S oc., 00, 11 : [ 14 ] Wang Bin, Xu Xihua. Nort hern Hemisphere summer mon soon singularities and climatological intraseasonal oscillation. J. Climate, 1997, 10 : [ 15 ] Teng Haiyan, Wang Bin. Interannual variations of t he boreal summer intraseasonal oscillation in the AsianPacific region. J. Climate, 003, 16 : [ 16 ] Li Tim, Wang Bin. A review on t he western Nort h Pacific monsoon : Synoptictointerannual variabilities. Terrestrial, A tmos pheric and Oceanic Sciences, 005, 16 : [ 17 ] Jiang Xianan, Li Tim, Wang Bin. Structures and mechanisms of t he nort hward propagating boreal summer intraseasonal oscillation. J. Climate, 004, 17 : [ 18 ],,.., 005, 63 (4) : Wang Hui, Ding Yihui, He Jinhai. The climate research of summer monsoon over the western North Pacific. A cta Mete or. S inica (in Chinese), 005, 63 (4) :

, 2 : ; 4 8, mm, mm, 43. 3% ; 350 mm, 70% , 32 d, d mm, 45. 1% mm, mm, 850 hpa (

, 2 : ; 4 8, mm, mm, 43. 3% ; 350 mm, 70% , 32 d, d mm, 45. 1% mm, mm, 850 hpa ( 26 1 2008 3 : 1006-7639 (2008) - 01-0001 - 07 AR ID METEOROLOGY Vol. 26 No. 1 March, 2008 2006, (, 211101) : NCEP OLR SST 2006, :, : ; ; ; ; : P458. 1 + 1 : A,,, [ 1 ] [ 2-5 ],, ( 400 m ),,, [ 6 ], 2006,