利用美国气象环境预报中心/美国国家大气研究中心(NCEP/NCAR)再分析资料以及局地纬向平均的经圈环流线性诊断方程, 诊断了1979—2010年6—8月南海夏季风期间经圈环流变化, 定量讨论了影响南海夏季风经向环流异常的主要物理过程。结果表明, 强南海夏季风年南海地区(10°—15°N)低层(900hPa)存在异常偏南风, 弱南海夏季风年南海地区低层存在异常偏北风。定量分析表明, 在强南海夏季风年对距平经圈环流低层经向分量起主要作用的是凝结潜热加热(68%)、体现越赤道气流影响的边界作用(14%)和潜热通量(12%); 对弱南海夏季风年距平经圈环流低层经向分量起主要作用的是凝结潜热加热(46%)、边界作用(38%)和热量垂直输送(13%)。分析对应的环流形势可知, 反映凝结潜热加热异常作用的副热带高压与反映边界作用的澳大利亚高压在强弱季风年表现出相反的特征。与海洋强迫有关的潜热通量对南海夏季风的强弱起了重要作用, 其在强、弱南海夏季风年的分布也存在明显差异: 强南海夏季风年异常潜热通量在南海分布为南正、北负, 弱夏季风年则相反。
Based on the National Centers for Environmental Prediction/the National Center for Atmospheric Research (NCEP/NCAR) reanalysis dataset, the meridional circulation of the South China Sea Summer Monsoon (SCSSM) in June-August from 1979 to 2010 is diagnosed using the linear diagnostic equation. The major processes that affect the meridional circulation of the SCSSM are discussed quantitatively. The anomalous meridional circulation indicates that the low-level (900-hPa) southerly over the SCS (10°-15°N) is stronger in strong SCSSM years than in normal years, and that in weak SCSSM years there exists stronger northerly in the SCS. The quantitative analysis shows that the contributions to the anomalous meridional component of the meridional circulation in the lower level over the SCS in anomalous strong SCSSM years are mainly from the processes related to latent heating (68%), boundary effect (or the effect of cross-equatorial flow) (14%), and air-sea latent-heat flux (12%). In weak SCSSM years, the contributions are mainly from the processes related to latent heat (46%), boundary effect (38%), and vertical transport of heat (13%). The general circulation associated with the major processes shows that the western Pacific Subtropical High (WPSH) related to latent heating and the Australia High (AH) associated with boundary effect have the opposite characteristics in strong/weak SCSSM years. Latent-heat flux also contributes to monsoon intensity. The distribution of latent-heat flux over the SCS is opposite in strong/weak SCSSM years. In the strong (weak) SCSSM years, the latent-heat flux anomalies is positive (negative) over the southern SCS and negative (positive) over the northern SCS.
[1]DING Y H, CHAN J C L. The East Asian summer monsoon: An overview[J]. Meteor Atmos Phys, 2005, 89: 117-142.
[2]GOSWAMI B N. The Asian monsoon: interdecadal variability[M]//The Asian Monsoon. Heidelberg: Springer Berlin, 2006: 295-327.
[3]DING Y H, WANG Z Y, SUN Y. Inter-decadal variation of the summer precipitation in East China and its association with decreasing Asian summer monsoon. Part Ⅰ: Observed evidences[J]. Int J Climatol, 2008, 228: 1139-1161.
[4]TANAKA H L, ISHIZKI N, KITOH A. Trend and interannual variability of Walker, monsoon and Hadley circulations defined by velocity potential in the upper troposphere[J]. Tellus A, 2004, 56, 250-269.
[5]GARCIA S R, KAYANO M T. Climatological aspects of Hadley, Walker and monsoon circulations in two phases of the Pacific Decadal Oscillation[J]. Theor Appl Climatol, 2008, 91: 117-127, doi: 10.1007/s00704-007-0301-9.
[6]陈月娟, 简俊, 张宏, 等. 1961—1997年110°—140°E垂直经圈环流的年际变化特征及其与海温变化的关系[J].大气科学, 2001, 25(1): 79-88.
[7]岳阳. 东亚夏季风经圈环流年际变化与大气对印度洋偶极型海温强迫的响应[D]. 南京：南京信息工程大学, 2007: 12-18.
[8]PILLAI P A, MOHANKUMAR K. Local Hadley circulation over the Asian monsoon region associated with the Tropospheric Biennial Oscillation[J]. Theor Appl Climatol, 2008, 91: 171-179, doi: 10.1007/s00704-007-0305-5.
[9]WANG Z F, QIAN Y F. The Relationship of Land-Ocean Thermal Anomaly Difference with Mei-yu and South China Sea Summer Monsoon [J]. Adv Atmos Sci, 2009, 26(1): 169-179.
[10]QIAN Y F, ZHANG Y, HUANG Y Y, et al. The effects of the thermal anomalies over the Tibetan Plateau and its vicinities on climate variability in China[J]. Adv Atmos Sci, 2004, 21(3): 369-381.
[11]李东辉, 张瑰, 朱益民, 等. 热带印度洋秋季偶极子模态与南海夏季风强度变化的关系[J]. 热带气象学报, 2006, 22(5): 439-446.
[12]冯娟, 李建平.南海夏季风变化及其与全球大气和海温的关系[J].大气科学, 2009, 33(3): 568-580.
[13]谷德军, 纪忠萍, 王东晓, 等.不同时间尺度上南海夏季风强度与海洋热力条件的关系[J]. 热带气象学报, 2007, 23(1): 14-20.
[14]LI C Y, LONG Z X, ZHANG Q Y. Strong/weak summer monsoon activity over the South China Sea and atmospheric intraseasonal oscillation[J]. Adv Atmos Sci, 2001, 18(6): 1146-1160.
[15]温之平.南海夏季风爆发的年际变化及其机制[D]. 北京: 中国科学院大气物理研究所, 2006: 133-148.
[16]袁卓建, 王同美. 局地经向环流的诊断方程[M]//东亚季风和中国暴雨. 北京: 气象出版社, 1998: 496-505.
[17]YUAN Z J, WANG T M, HE H Y, et al. A Comparison between numerical simulations of forced Local Hadley Circulation in East Asian and Indian Monsoon Regions [J]. Adv Atmos Sci, 2000, 17(4): 538-554.
[18]覃惠玲, 简茂球, 袁卓建, 等. 1984年南海夏季风经向环流强迫因子的诊断分析[J]. 热带气象学报, 2004, 20(1): 39-49.
[19]严蜜, 钱永甫. 南海夏季风强弱年东亚地表热力异常特征的合成研究[J].中山大学学报: 自然科学版, 2009, 48(2): 124-130.
[20]袁卓建, 王同美, 郭裕福. 东亚季风经向环流数值模拟及结果分析——Ⅰ算法设计[J]. 中山大学学报: 自然科学版, 2000, 39(6):112-116.
[21]王同美, 袁卓建, 郭裕福.东亚季风经向环流数值模拟及结果分析——Ⅱ模式性能检测及个例分析[J]. 中山大学学报: 自然科学版, 2001, 40(1): 97-100.
[22]梁肇宁, 温之平, 袁卓建, 等. 影响1991年和1994年南海夏季风爆发迟早的物理因子探讨[J]. 大气科学, 2004, 28(2): 216-230.
[23]吴尚森, 梁建茵. 南海夏季风强度指数及其变化特征[J]. 热带气象学报, 2001, 17(4): 337-344.
[24]LI J P, ZENG Q C. A new monsoon index and the geographical distribution of the global monsoons[J]. Adv Atmos Sci, 2003, 20: 299-302.
[25]张勇, 谢安, 戴年军.南海夏季风异常活动的前期特征[J].热带气象学报, 2004, 20: 460-471.
[26]XU Z F, FU C B, QIAN Y F. A new index to describe the tropical Asian monsoon[J]. Sci Chin Ser D: Earth Sci, 2009, 52(6):843-854, doi: 10.1007/s11430-009-058-3.
[27]ELIASSEN A. Slow thermally or frictionally controlled meridional circulation in a circular vortex[J]. Astrophysics Norvegica, 1951, 5: 19-60.
[28]陈桂兴, 袁卓建, 梁建茵, 等. 南海夏季风经向环流的20年平均4—6月演变机制[J]. 气候与环境研究, 2004, 9(4): 605-618.
[29]温之平, 吴乃庚, 冯业荣, 等. 定量诊断华南春旱形成机理[J]. 大气科学, 2007, 31(6): 1223-1236.
[30]方宇凌, 简茂球. 2003年夏季华南持续高温天气过程及热力诊断[J]. 热带海洋学报, 2011, 30(3): 30-37.
[31]刘艳菊, 闫俊岳, 丁一汇. 南海夏季风异常及其对南海与周边地区的大气和海洋要素的影响[J]. 海洋学报, 2008, 30(6): 39-50.
[32]滕代高, 刘宣飞, 张增信, 等. 澳大利亚高压的年际变化及其对应的亚澳季风[J]. 南京气象学院学报, 2005, 28(1): 86-92.
[33]王丽娟. 南海海气界面潜热通量对南海夏季风爆发影响的研究[D]. 北京: 中国气象科学研究院, 2008: 64-69.
[34]ZHOU B T, WANG H J. Relationship between the boreal spring Hadley circulation and the summer precipitation in the Yangtze River valley[J]. J Geophys Res, 2006, 111, D16109, doi:10.1029/2005JD007006.
[35]余丹丹, 张韧, 洪梅, 等. 亚洲夏季风系统成员与西太平洋副高的相关特征分析[J]. 热带气象学报, 2007, 23(1): 78-84.
[36]LI W B, FENG J X, CHEN S M, et al. Relationship between wintertime precipitation in South China and air-sea heat ?uxes[J]. Atmos Sci Let, 2012, doi: 10.1002/asl.370.
