中东太平洋ITCZ对两类厄尔尼诺SST异常的敏感性试验
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摘要
利用MPAS-A(The Model for Prediction Across Scales-Atmosphere)模式设计了中东太平洋热带辐合带CEP-ITCZ(Intertropical Convergence Zone over Central and Eastern Pacific)对两类厄尔尼诺SST(Sea Surface Temperature)异常的敏感性试验,通过试验结果与两类厄尔尼诺年实际大气异常的对比,初步解释了CEP-ITCZ在两类厄尔尼诺年产生不同异常的可能原因。通过CP-EL试验发现,热带太平洋SST异常的第一模态会使中东太平洋低层风场辐合增强,但对辐合带的位置影响不大,与中部型厄尔尼诺对CEP-ITCZ的影响基本一致。通过EP-EL试验发现,热带太平洋SST异常的第二模态会使中东太平洋低层风场产生较大异常,辐合带中心向南移动,辐合带明显减弱增宽,与东部型厄尔尼诺对CEP-ITCZ的影响基本一致。
Intertropical Convergence Zone( ITCZ),as one of the important systems of tropical atmosphere,has important impacts on global atmospheric circulation.Due to a range of factors,regional ITCZ has different characteristics.Among them,the Central and Eastern Pacific ITCZ( CEP-ITCZ) is located to the north of the equator year round w ith high particularity relative to other regions.In addition to seasonal movement,the meridian position of CEP-ITCZ is usually affected by El Niňo events. Some researchers have found that the CEP-ITCZ is slightly southw ard in Central Pacific El Niňo( CP-El Niňo) year,and the southw ard extent is less than that in Eastern Pacific El Niňo( EP-El Niňo) year.Therefore,taking into account that the location and intensity of CP-El Niňo and EP-El Niňo are very different,their impacts on the CEP-ITCZ inevitably vary w idely. Previous studies have not analyzed this variation in depth,especially the difference betw een the impacts from tw o types of El Niňo on the intensity of CEP-ITCZ.The research about how the anomaly of SST( Sea Surface Temperature) impacts ITCZ is of great significance to the mechanism of air-sea interaction,climatic prediction and model assessment.In the passage,tw o sensitivity tests about impacts of SST anomaly on CEP-ITCZ w ere implied using M PAS-A( The M odel for Prediction Across Scales-Atmosphere) model.Compared w ith the anomalies of real atmosphere in tw o types of El Niňo years,the reasons w hy the CEP-ITCZ presents different characteristics in tw o types of El Niňo w ere proposed.The results of CP-EL test show that due to the impact from the first mode of SST anomaly in the tropical Pacific,the anomalies of the meridional w inds in the northern and southern hemispheres are comparable,and the anomalous cross-equatorial flow is w eak,resulting in little changes in the CEP-ITCZ position. The anomalies of the meridional w inds lead to the convergence zone slightly stronger. The precipitation of CEP-ITCZ is enhanced by both w ind convergence and SST positive anomalies. These results are consistent w ith the anomalies of CEPITCZ in central pacific El Niňo years.The results of EP-EL test show that due to the impacts from the first tw o modes of SST anomaly in the tropical Pacific,the anomalies of the meridional w inds in the northern hemisphere are strong,w hich results in a higher extent of southw ard movement for the CEP-ITCZ.Due to the impacts from anomalous meridional w ind,the anomalies of divergence show dipole-like pattern,w hich increases the w idth and w eakens the central intensity of the convergence zone. These results are consistent w ith the anomalies of CEPITCZ in eastern pacific El Niňo years.The second mode of SST anomaly may have an important impact on CEPITCZ.The intensities of the second mode of SST anomaly in tw o types of El Nino years are quite different,w hich results in the southw ard extent of CEP-ITCZ in CP-El Niňo years is less than that in EP-El Niňo years,w hile the precipitation intensities of the CEP-ITCZ in tw o types of El Niňo years are similar.
Intertropical Convergence Zone( ITCZ),as one of the important systems of tropical atmosphere,has important impacts on global atmospheric circulation.Due to a range of factors,regional ITCZ has different characteristics.Among them,the Central and Eastern Pacific ITCZ( CEP-ITCZ) is located to the north of the equator year round w ith high particularity relative to other regions.In addition to seasonal movement,the meridian position of CEP-ITCZ is usually affected by El Niňo events. Some researchers have found that the CEP-ITCZ is slightly southw ard in Central Pacific El Niňo( CP-El Niňo) year,and the southw ard extent is less than that in Eastern Pacific El Niňo( EP-El Niňo) year.Therefore,taking into account that the location and intensity of CP-El Niňo and EP-El Niňo are very different,their impacts on the CEP-ITCZ inevitably vary w idely. Previous studies have not analyzed this variation in depth,especially the difference betw een the impacts from tw o types of El Niňo on the intensity of CEP-ITCZ.The research about how the anomaly of SST( Sea Surface Temperature) impacts ITCZ is of great significance to the mechanism of air-sea interaction,climatic prediction and model assessment.In the passage,tw o sensitivity tests about impacts of SST anomaly on CEP-ITCZ w ere implied using M PAS-A( The M odel for Prediction Across Scales-Atmosphere) model.Compared w ith the anomalies of real atmosphere in tw o types of El Niňo years,the reasons w hy the CEP-ITCZ presents different characteristics in tw o types of El Niňo w ere proposed.The results of CP-EL test show that due to the impact from the first mode of SST anomaly in the tropical Pacific,the anomalies of the meridional w inds in the northern and southern hemispheres are comparable,and the anomalous cross-equatorial flow is w eak,resulting in little changes in the CEP-ITCZ position. The anomalies of the meridional w inds lead to the convergence zone slightly stronger. The precipitation of CEP-ITCZ is enhanced by both w ind convergence and SST positive anomalies. These results are consistent w ith the anomalies of CEPITCZ in central pacific El Niňo years.The results of EP-EL test show that due to the impacts from the first tw o modes of SST anomaly in the tropical Pacific,the anomalies of the meridional w inds in the northern hemisphere are strong,w hich results in a higher extent of southw ard movement for the CEP-ITCZ.Due to the impacts from anomalous meridional w ind,the anomalies of divergence show dipole-like pattern,w hich increases the w idth and w eakens the central intensity of the convergence zone. These results are consistent w ith the anomalies of CEPITCZ in eastern pacific El Niňo years.The second mode of SST anomaly may have an important impact on CEPITCZ.The intensities of the second mode of SST anomaly in tw o types of El Nino years are quite different,w hich results in the southw ard extent of CEP-ITCZ in CP-El Niňo years is less than that in EP-El Niňo years,w hile the precipitation intensities of the CEP-ITCZ in tw o types of El Niňo years are similar.
引文
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冯娟,管兆勇,王黎娟,等,2010.夏季热带中太平洋SST异常型与中国东部夏季气候异常的关系[J].大气科学学报,33(5):547-554.Feng J,Guan Z Y,Wang L J,et al.,2010.Impact of central equatorial Pacific SSTA pattern on precipitation and temperature in East China in summer[J].Trans Atmos Sci,33(5):547-554.(in Chinese).
Hagos S,Leung R,Rauscher S A,et al.,2013.Error characteristics of two grid refinement approaches in aquaplanet simulations:MPAS-A and WRF[J].Mon Wea Rev,141(9):3022-3036.
Kao H Y,Yu J Y,2009.Contrasting eastern-Pacific and central-Pacific types of ENSO[J].J Climate,22(3):615-632.
Karumuri A,Swadhin B,Suryachandra A R,et al.,2007.El Niňo Modoki and its possible teleconnection[J].J Geophys Res Atmos,112(C11):C11007.
Kug J S,Jin F F,An S I,2009.Two types of El Niňo events:cold tongue El Niňo and warm pool El Niňo[J].J Climate,22(6):1499-1515.
Larkin N K,Harrison D E,2005.On the definition of El Niňo and associated seasonal average U.S.weather anomalies[J].Geophys Res Lett,32:L13705.
Lengaigne M,Vecchi G A,2010.Contrasting the termination of moderate and extreme El Niňo events in coupled general circulation models[J].Clim Dyn,35(2):299-313.
李丽平,宋哲,吴楠,2015.三类厄尔尼诺事件对东亚大气环流及中国东部次年夏季降水的影响[J].大气科学学报,38(6):753-765.Li L P,Song Z,Wu N,2015.Effects of three types of El Niňo events on atmospheric circulation over East Asia and following summer precipitation in eastern China[J].Trans Atmos Sci,38(6):753-765.(in Chinese).
刘维,刘宇迪,赵世梅,2016.二十面体网格和经纬网格全球模式在中国区域模拟效果对比[J].南京信息工程大学学报(自然科学版),8(2):146-151.Liu W,Liu Y D,Zhao S M,2016.Global mode simulation results comparison between icosahedron spherical mesh and latitude-longitude mesh in China[J].Journal of Nanjing University of Information Science & Technology (Natural Science Edition),8(2):146-151.(in Chinese).
Lorenz E N,1955.Available potential energy and the maintenance of the general circulation[J].Tellus,7(2):157-167.
Nickovic S,1994.On the use of hexagonal grids for simulation of atmospheric processes[J].Contrib Atmos Phys,67:103-107.
North G R,Bell T,Cahalan R,1982.Sampling errors in the estimation of empirical orthogonal function[J].Mon Wea Rev,110:699-706.
Park S,Klemp J B,Skamarock W C,2014.A comparison of mesh refinement in the global MPAS-A and WRF models using an idealized normal-mode baroclinic wave simulation[J].Mon Wea Rev,142(10):3614-3634.
秦坚肇,王亚非,2014.构建描述两种ENSO类型的新指数[J].气象学报,72(3):526-541.Qin J Z,Wang Y F,2014.Construction of new indices for two types of ENSO events[J].Acta Meteorological Sinica,72(3):526-541.(in Chinese).
Ryan E S,Jonathan H J,Dong X Q,et al.,2016.A quantitative assessment of precipitation associated with the ITCZ in the CMIP5 GCM simulations[J].Clim Dyn,47(5):1863-1880.
Skamarock W C,Klemp J B,Duda M G,et al.,2012.A multiscale nonhydrostatic atmospheric model using centroidal voronoi tesselations and C-grid staggering[J].Mon Wea Rev,140(9):3090-3105.
隋晓霞,王启,2011.北太平洋热带辐合带区上升运动的季节和年际变化特征[J].中国海洋大学学报,41(4):19-27.Sui X X,Wang Q,2011.The seasonal and interannual features of ascending motion intensity and position in the intertropical convergence zone in the North Pacific[J].Journal of Ocean University of China,41(4):19-27.(in Chinese).
Vecchi G A,Harrison D E,2006.The termination of the 1997—98 El Niňo.Part I:mechanisms of Oceanic Change[J].J Climate,19(12):2633-2646.
Wang C,Wang X,2013.Classifying El Niňo modoki I and II by different impacts on rainfall in southern China and typhoon tracks[J].J Climate,26(4):1322-1338.
王美,管兆勇,皮东勤,2016.冬季赤道太平洋不同类型海温异常表征指数的再构建[J].大气科学学报,39(4):455-467.Wang M,Guan Z Y,Pi D Q,2016.Reconstruction of equatorial Pacific SST anomaly indices for two types of ENSO during boreal winter[J].Trans Atmos Sci,39(4):455-467.(in Chinese).
Webster P J,1972.Response of the tropical atmosphere to local,steady forcing[J].Mon Wea Rev,100(7):518-541.
Weng H,Behera S K,Yamagata T,2009.Anomalous winter climate conditions in the Pacific rim during recent El Niňo Modoki and El Niňo events[J].Clim Dyn,32(5):663-674.
Xie S P,1996.Westward propagation of latitudinal asymmetry in a coupled ocean-atmosphere model[J].J Atmos Sci,53(22):3236-3250.
Xie S P,Philander S G H,1994.A coupled ocean-atmosphere model of relevance to the ITCZ in the eastern Pacific[J].Tellus,46(4):340-350.
Xie R H,Yang Y X,2015.Revisiting the latitude fluctuations of the eastern Pacific ITCZ during the central Pacific El Niňo[J].Geophys Res Lett,41(22):7770-7776.
Xie R H,Huang F,Jin F F,et al.,2014.The impact of basic state on quasi-biennial periodicity of central Pacific ENSO over the pastdecade[J].Theor Appl Climatol,120(1):55-67.
张攀全,郭品文,董丽娜,等,2016.两类中太平洋El Niňo特征的对比分析[J].大气科学学报,39(6):855-864.Zhang P Q,Guo P W,Dong L N,et al.,2016.Comparative analysis of characteristics of two types of central Pacific El Niňo [J].Trans Atmos Sci,39(6):855-864.(in Chinese).
张文君,耿新,2016.2015/2016年超强El Niňo局地海气特征及其特殊性[J].大气科学学报,39(6):778-787.Zhang W J,Geng X,2016.Characteristics and particularity of local air-sea processes for the 2015/2016 super El Niňo event[J].Trans Atmos Sci,39(6):778-787.(in Chinese).
冯娟,管兆勇,王黎娟,等,2010.夏季热带中太平洋SST异常型与中国东部夏季气候异常的关系[J].大气科学学报,33(5):547-554.Feng J,Guan Z Y,Wang L J,et al.,2010.Impact of central equatorial Pacific SSTA pattern on precipitation and temperature in East China in summer[J].Trans Atmos Sci,33(5):547-554.(in Chinese).
Hagos S,Leung R,Rauscher S A,et al.,2013.Error characteristics of two grid refinement approaches in aquaplanet simulations:MPAS-A and WRF[J].Mon Wea Rev,141(9):3022-3036.
Kao H Y,Yu J Y,2009.Contrasting eastern-Pacific and central-Pacific types of ENSO[J].J Climate,22(3):615-632.
Karumuri A,Swadhin B,Suryachandra A R,et al.,2007.El Niňo Modoki and its possible teleconnection[J].J Geophys Res Atmos,112(C11):C11007.
Kug J S,Jin F F,An S I,2009.Two types of El Niňo events:cold tongue El Niňo and warm pool El Niňo[J].J Climate,22(6):1499-1515.
Larkin N K,Harrison D E,2005.On the definition of El Niňo and associated seasonal average U.S.weather anomalies[J].Geophys Res Lett,32:L13705.
Lengaigne M,Vecchi G A,2010.Contrasting the termination of moderate and extreme El Niňo events in coupled general circulation models[J].Clim Dyn,35(2):299-313.
李丽平,宋哲,吴楠,2015.三类厄尔尼诺事件对东亚大气环流及中国东部次年夏季降水的影响[J].大气科学学报,38(6):753-765.Li L P,Song Z,Wu N,2015.Effects of three types of El Niňo events on atmospheric circulation over East Asia and following summer precipitation in eastern China[J].Trans Atmos Sci,38(6):753-765.(in Chinese).
刘维,刘宇迪,赵世梅,2016.二十面体网格和经纬网格全球模式在中国区域模拟效果对比[J].南京信息工程大学学报(自然科学版),8(2):146-151.Liu W,Liu Y D,Zhao S M,2016.Global mode simulation results comparison between icosahedron spherical mesh and latitude-longitude mesh in China[J].Journal of Nanjing University of Information Science & Technology (Natural Science Edition),8(2):146-151.(in Chinese).
Lorenz E N,1955.Available potential energy and the maintenance of the general circulation[J].Tellus,7(2):157-167.
Nickovic S,1994.On the use of hexagonal grids for simulation of atmospheric processes[J].Contrib Atmos Phys,67:103-107.
North G R,Bell T,Cahalan R,1982.Sampling errors in the estimation of empirical orthogonal function[J].Mon Wea Rev,110:699-706.
Park S,Klemp J B,Skamarock W C,2014.A comparison of mesh refinement in the global MPAS-A and WRF models using an idealized normal-mode baroclinic wave simulation[J].Mon Wea Rev,142(10):3614-3634.
秦坚肇,王亚非,2014.构建描述两种ENSO类型的新指数[J].气象学报,72(3):526-541.Qin J Z,Wang Y F,2014.Construction of new indices for two types of ENSO events[J].Acta Meteorological Sinica,72(3):526-541.(in Chinese).
Ryan E S,Jonathan H J,Dong X Q,et al.,2016.A quantitative assessment of precipitation associated with the ITCZ in the CMIP5 GCM simulations[J].Clim Dyn,47(5):1863-1880.
Skamarock W C,Klemp J B,Duda M G,et al.,2012.A multiscale nonhydrostatic atmospheric model using centroidal voronoi tesselations and C-grid staggering[J].Mon Wea Rev,140(9):3090-3105.
隋晓霞,王启,2011.北太平洋热带辐合带区上升运动的季节和年际变化特征[J].中国海洋大学学报,41(4):19-27.Sui X X,Wang Q,2011.The seasonal and interannual features of ascending motion intensity and position in the intertropical convergence zone in the North Pacific[J].Journal of Ocean University of China,41(4):19-27.(in Chinese).
Vecchi G A,Harrison D E,2006.The termination of the 1997—98 El Niňo.Part I:mechanisms of Oceanic Change[J].J Climate,19(12):2633-2646.
Wang C,Wang X,2013.Classifying El Niňo modoki I and II by different impacts on rainfall in southern China and typhoon tracks[J].J Climate,26(4):1322-1338.
王美,管兆勇,皮东勤,2016.冬季赤道太平洋不同类型海温异常表征指数的再构建[J].大气科学学报,39(4):455-467.Wang M,Guan Z Y,Pi D Q,2016.Reconstruction of equatorial Pacific SST anomaly indices for two types of ENSO during boreal winter[J].Trans Atmos Sci,39(4):455-467.(in Chinese).
Webster P J,1972.Response of the tropical atmosphere to local,steady forcing[J].Mon Wea Rev,100(7):518-541.
Weng H,Behera S K,Yamagata T,2009.Anomalous winter climate conditions in the Pacific rim during recent El Niňo Modoki and El Niňo events[J].Clim Dyn,32(5):663-674.
Xie S P,1996.Westward propagation of latitudinal asymmetry in a coupled ocean-atmosphere model[J].J Atmos Sci,53(22):3236-3250.
Xie S P,Philander S G H,1994.A coupled ocean-atmosphere model of relevance to the ITCZ in the eastern Pacific[J].Tellus,46(4):340-350.
Xie R H,Yang Y X,2015.Revisiting the latitude fluctuations of the eastern Pacific ITCZ during the central Pacific El Niňo[J].Geophys Res Lett,41(22):7770-7776.
Xie R H,Huang F,Jin F F,et al.,2014.The impact of basic state on quasi-biennial periodicity of central Pacific ENSO over the pastdecade[J].Theor Appl Climatol,120(1):55-67.
张攀全,郭品文,董丽娜,等,2016.两类中太平洋El Niňo特征的对比分析[J].大气科学学报,39(6):855-864.Zhang P Q,Guo P W,Dong L N,et al.,2016.Comparative analysis of characteristics of two types of central Pacific El Niňo [J].Trans Atmos Sci,39(6):855-864.(in Chinese).
张文君,耿新,2016.2015/2016年超强El Niňo局地海气特征及其特殊性[J].大气科学学报,39(6):778-787.Zhang W J,Geng X,2016.Characteristics and particularity of local air-sea processes for the 2015/2016 super El Niňo event[J].Trans Atmos Sci,39(6):778-787.(in Chinese).