本文基于观测资料和LICOM2.0模拟结果的分析研究,简要介绍讨论了太平洋—印度洋海温(异常)联合模(PIOAM)的存在、特征、演变及其影响等问题。热带太平洋—印度洋区域乃至全球范围的海表温度异常(SSTA)资料进行EOF分解,都清楚表明其第一...本文基于观测资料和LICOM2.0模拟结果的分析研究,简要介绍讨论了太平洋—印度洋海温(异常)联合模(PIOAM)的存在、特征、演变及其影响等问题。热带太平洋—印度洋区域乃至全球范围的海表温度异常(SSTA)资料进行EOF分解,都清楚表明其第一分量在热带太平洋—印度洋的空间形态与太平洋—印度洋海温(异常)联合模(PIOAM)非常相似,说明PIOAM是热带太平洋—印度洋实实在在存在的一种海温异常模态。对应PIOAM的正、负位相,热带印度洋和西太平洋地区的夏季(JJA)850 h Pa距平风场有近乎相反的异常流场形势;对流层低层的Walker环流支和亚洲夏季风都出现了不同特征的(近乎相反)异常;在PIOAM正(负)位相将使得100 h Pa的南亚高压位置偏东(西)。对热带太平洋和印度洋温跃层曲面上的海温异常(为了方便将其称为SOTA)进行EOF分解,发现其第一模态也是一个三极子模态,即当赤道中西印度洋大部分海域与赤道中东太平洋大部分海域偏暖(偏冷)时,赤道东印度洋和赤道西太平洋大部分海域则偏冷(偏暖);它与太平洋—印度洋表层的PIOAM十分类似,也表明PIOAM在海洋次表层也是存在的。高分辨海洋环流模式LICOM2.0的模拟结果,无论是对太平洋—印度洋表层还是次表层的PIOAM的特征和演变都刻画得很好,这从另一个角度进一步说明PIOAM是热带太平洋—印度洋实际存在的一种海温变化模态。PIOAM正、负位相不仅对亚洲及西太平洋地区的天气气候有非常不一样的影响(不少地方有反向的特征),还会对南北美洲和非洲一些地区产生不同影响;而且其影响与单独的厄尔尼诺(El Ni?o)及印度洋偶极子(IOD)都不尽相同。展开更多
This study utilizes a new monthly-assimilated sea temperature and analyzes trend and decadal oscillations in tropical Pacific 100 200 m subsurface ocean temperature (SOT) from 1945 to 2005 on the basis of the harmonic...This study utilizes a new monthly-assimilated sea temperature and analyzes trend and decadal oscillations in tropical Pacific 100 200 m subsurface ocean temperature (SOT) from 1945 to 2005 on the basis of the harmonic analysis and Empirical Orthogonal Function (EOF) methods.Significant cooling trends in the SOT in the tropical western Pacific were found over this 60-year period.The first EOF of the SOT in tropical Pacific displays an ENSO-like zonal dipole pattern on decadal time scale,and we considered this pattern in subsurface ocean temperature the tropical Pacific decadal oscillation (TPDO).Our analysis suggests that TPDO is closely correlated with the Pacific decadal oscillation (PDO) in the surface sea temperature (SST).The correlation coefficient between the indices of TPDO and PDO is +0.81 and reaches a maximum of +0.84 when TPDO lags behind PDO by 2 months.Therefore,a change of TPDO is likely related to the variation of PDO.The long-term change in TPDO best explains decadal warming in the tropical eastern Pacific SST and implies potential impact on the weakening of East Asian summer monsoons after the late 1970s.展开更多
The inter-annual variability of the tropical Pacific Subsurface Ocean Temperature Anomaly （SOTA） and the associated anomalous atmospheric circulation over the Asian North Pacific during the E1 Nifio-Southern Oscilla...The inter-annual variability of the tropical Pacific Subsurface Ocean Temperature Anomaly （SOTA） and the associated anomalous atmospheric circulation over the Asian North Pacific during the E1 Nifio-Southern Oscillation （ENSO） were investigated using National Centers for Environmental Prediction/ National Center for Atmospheric Research （NCEP/NCAR） atmospheric reanalysis data and simple ocean data simulation （SODA）. The relationship between the ENSO and the climate of China was revealed. The main results indicated the following： 1） there are two ENSO modes acting on the subsurface tropical Pacific. The first mode is related to the mature phase of ENSO, which mainly appears during winter. The second mode is associated with a transition stage of the ENSO developing or decaying, which mainly occurs during summer; 2） during the mature phase of E1Nifio, the meridionality of the atmosphere in the mid-high latitude increases, the Aleutian low and high pressure ridge over Lake Baikal strengthens, northerly winds prevail in northern China, and precipitation in northern China decreases significantly. The ridge of the Ural High strengthens during the decaying phase of E1 Nifio, as atmospheric circulation is sustained during winter, and the northerly wind anomaly appears in northern China during summer. Due to the ascending branch of the Walker circulation over the western Pacific, the western Pacific Subtropical High becomes weaker, and south-southeasterly winds prevail over southern China. As a result, less rainfall occurs over northern China and more rainfall over the Changjiang River basin and the southwestern and eastern region of Inner Mongolia. The flood disaster that occurred south of Changjiang River can be attributed to this. The La Nifm event causes an opposite, but weaker effect; 3） the ENSO cycle can influence climate anomalies within China via zonal and meridional heat transport. This is known as the ＂atmospheric-bridge＂, where the energy anomaly within the tropical Pacific transfers to the mid-high latitude in the northern Pacific through Hadley cells and Rossby waves, and to the western Pacific-eastern Indian Ocean through Walker circulation. This research also discusses the special air-sea boundary processes during the ENSO events in the tropical Pacific, and indicates that the influence of the subsurface water of the tropical Pacific on the atmospheric circulation may be realized through the sea surface temperature anomalies of the mixed water, which contact the atmosphere and transfer the anomalous heat and moisture to the atmosphere directly. Moreover, the reason for the heavy flood within the Changjiang River during the summer of 1998 is reviewed in this paper.展开更多
The nature decadal variability of the equatorial Pacific subsurface temperature is examined in the control simulation with the Geophysical Fluid Dynamics Laboratory coupled model CM2.1.The dominant mode of the subsurf...The nature decadal variability of the equatorial Pacific subsurface temperature is examined in the control simulation with the Geophysical Fluid Dynamics Laboratory coupled model CM2.1.The dominant mode of the subsurface temperature variations in the equator Pacific features a 20-40 year period and is North-South asymmetric about the equator.Decadal variations of the thermocline are most pronounced in the southwest of the Tropical Pacific.Decadal variation of the north-south asymmetric Sea Surface wind in the tropical Pacific,especially in the South Pacific Convergence,is the dominant mechanism of the nature decadal variation of the subsurface temperature in the equatorial Pacific.展开更多
基金supported by the Key Project of the National Natural Science Foundation of China[grant number 42192563]the International Cooperation and Exchange Program of the National Natural Science Foundation of China[grant number 42120104001].
文摘本文基于观测资料和LICOM2.0模拟结果的分析研究,简要介绍讨论了太平洋—印度洋海温(异常)联合模(PIOAM)的存在、特征、演变及其影响等问题。热带太平洋—印度洋区域乃至全球范围的海表温度异常(SSTA)资料进行EOF分解,都清楚表明其第一分量在热带太平洋—印度洋的空间形态与太平洋—印度洋海温(异常)联合模(PIOAM)非常相似,说明PIOAM是热带太平洋—印度洋实实在在存在的一种海温异常模态。对应PIOAM的正、负位相,热带印度洋和西太平洋地区的夏季(JJA)850 h Pa距平风场有近乎相反的异常流场形势;对流层低层的Walker环流支和亚洲夏季风都出现了不同特征的(近乎相反)异常;在PIOAM正(负)位相将使得100 h Pa的南亚高压位置偏东(西)。对热带太平洋和印度洋温跃层曲面上的海温异常(为了方便将其称为SOTA)进行EOF分解,发现其第一模态也是一个三极子模态,即当赤道中西印度洋大部分海域与赤道中东太平洋大部分海域偏暖(偏冷)时,赤道东印度洋和赤道西太平洋大部分海域则偏冷(偏暖);它与太平洋—印度洋表层的PIOAM十分类似,也表明PIOAM在海洋次表层也是存在的。高分辨海洋环流模式LICOM2.0的模拟结果,无论是对太平洋—印度洋表层还是次表层的PIOAM的特征和演变都刻画得很好,这从另一个角度进一步说明PIOAM是热带太平洋—印度洋实际存在的一种海温变化模态。PIOAM正、负位相不仅对亚洲及西太平洋地区的天气气候有非常不一样的影响(不少地方有反向的特征),还会对南北美洲和非洲一些地区产生不同影响;而且其影响与单独的厄尔尼诺(El Ni?o)及印度洋偶极子(IOD)都不尽相同。
基金The National Natural Science Foundation ofChina (Grant Nos. 90711003 and 40921003)Chinese Coordinated Observation and Prediction of climate System (ChineseCOPES) program (Grant No. GYHY200706005) jointly supportedthis study
文摘This study utilizes a new monthly-assimilated sea temperature and analyzes trend and decadal oscillations in tropical Pacific 100 200 m subsurface ocean temperature (SOT) from 1945 to 2005 on the basis of the harmonic analysis and Empirical Orthogonal Function (EOF) methods.Significant cooling trends in the SOT in the tropical western Pacific were found over this 60-year period.The first EOF of the SOT in tropical Pacific displays an ENSO-like zonal dipole pattern on decadal time scale,and we considered this pattern in subsurface ocean temperature the tropical Pacific decadal oscillation (TPDO).Our analysis suggests that TPDO is closely correlated with the Pacific decadal oscillation (PDO) in the surface sea temperature (SST).The correlation coefficient between the indices of TPDO and PDO is +0.81 and reaches a maximum of +0.84 when TPDO lags behind PDO by 2 months.Therefore,a change of TPDO is likely related to the variation of PDO.The long-term change in TPDO best explains decadal warming in the tropical eastern Pacific SST and implies potential impact on the weakening of East Asian summer monsoons after the late 1970s.
基金Supported by the Knowledge Innovation Program of Chinese Academy of Sciences (No. KZCX2-YW-Q11-02)the CAS Strategic Priority Research Program (No. XDA05090404)the National Basic Research Program of China (973 Program) (No. 2012CB417401)
文摘The inter-annual variability of the tropical Pacific Subsurface Ocean Temperature Anomaly （SOTA） and the associated anomalous atmospheric circulation over the Asian North Pacific during the E1 Nifio-Southern Oscillation （ENSO） were investigated using National Centers for Environmental Prediction/ National Center for Atmospheric Research （NCEP/NCAR） atmospheric reanalysis data and simple ocean data simulation （SODA）. The relationship between the ENSO and the climate of China was revealed. The main results indicated the following： 1） there are two ENSO modes acting on the subsurface tropical Pacific. The first mode is related to the mature phase of ENSO, which mainly appears during winter. The second mode is associated with a transition stage of the ENSO developing or decaying, which mainly occurs during summer; 2） during the mature phase of E1Nifio, the meridionality of the atmosphere in the mid-high latitude increases, the Aleutian low and high pressure ridge over Lake Baikal strengthens, northerly winds prevail in northern China, and precipitation in northern China decreases significantly. The ridge of the Ural High strengthens during the decaying phase of E1 Nifio, as atmospheric circulation is sustained during winter, and the northerly wind anomaly appears in northern China during summer. Due to the ascending branch of the Walker circulation over the western Pacific, the western Pacific Subtropical High becomes weaker, and south-southeasterly winds prevail over southern China. As a result, less rainfall occurs over northern China and more rainfall over the Changjiang River basin and the southwestern and eastern region of Inner Mongolia. The flood disaster that occurred south of Changjiang River can be attributed to this. The La Nifm event causes an opposite, but weaker effect; 3） the ENSO cycle can influence climate anomalies within China via zonal and meridional heat transport. This is known as the ＂atmospheric-bridge＂, where the energy anomaly within the tropical Pacific transfers to the mid-high latitude in the northern Pacific through Hadley cells and Rossby waves, and to the western Pacific-eastern Indian Ocean through Walker circulation. This research also discusses the special air-sea boundary processes during the ENSO events in the tropical Pacific, and indicates that the influence of the subsurface water of the tropical Pacific on the atmospheric circulation may be realized through the sea surface temperature anomalies of the mixed water, which contact the atmosphere and transfer the anomalous heat and moisture to the atmosphere directly. Moreover, the reason for the heavy flood within the Changjiang River during the summer of 1998 is reviewed in this paper.
基金supported by the Ministry of Science and the Technology of China (National Basic Research Program of China 2012CB955602)Natural Science Foundation of China (40830106,40921004 and 41176006)
文摘The nature decadal variability of the equatorial Pacific subsurface temperature is examined in the control simulation with the Geophysical Fluid Dynamics Laboratory coupled model CM2.1.The dominant mode of the subsurface temperature variations in the equator Pacific features a 20-40 year period and is North-South asymmetric about the equator.Decadal variations of the thermocline are most pronounced in the southwest of the Tropical Pacific.Decadal variation of the north-south asymmetric Sea Surface wind in the tropical Pacific,especially in the South Pacific Convergence,is the dominant mechanism of the nature decadal variation of the subsurface temperature in the equatorial Pacific.
