The Kuqa and the Southern Junggar foreland thrust belts, which lie to the southern and northern Tianshan, respectively, were formed under a strong compressional tectonic setting. Due to the differential propagation an...The Kuqa and the Southern Junggar foreland thrust belts, which lie to the southern and northern Tianshan, respectively, were formed under a strong compressional tectonic setting. Due to the differential propagation and deformation under the control of the décollement horizon, the structural deformation styles differ in the Kuqa and Southern Junggar thrust belts. Imbricated stacking is developed in the Kuqa thrust belt, forming a piggyback imbricated pattern of faulted anticline and fault-block structural assemblage dominated by salt structures. In contrast, wedge-shaped thrusts are developed in Southern Junggar, mainly forming vertical laminated patterns of multi-wedge-structure stacks strongly influenced by the décollement horizons. The different deformation patterns and structural styles of the north and south of Tian Shan control the contrasting characteristics of hydrocarbon accumulation in the foreland thrust belts of the Kuqa and the Southern Junggar thrust belts, including the variance in the hydrocarbon trap types, pathway systems and hydrocarbon-bearing horizons. Proven by the hydrocarbon accumulation research and exploration achievements, recent exploration targets should focus on sub-salt piggyback imbricated structural patterns in the Kuqa and the deep laminated patterns in the Southern Junggar thrust belt.展开更多
A class of coupled system for the E1 Nifio-Southern Oscillation (ENSO) mechanism is studied. Using the method of variational iteration for perturbation theory, the asymptotic expansions of the solution for ENSO mode...A class of coupled system for the E1 Nifio-Southern Oscillation (ENSO) mechanism is studied. Using the method of variational iteration for perturbation theory, the asymptotic expansions of the solution for ENSO model are obtained and the asymptotic behaviour of solution for corresponding problem is considered.展开更多
The EI Nino/La Nina-Southern Oscillation (ENSO) is an interannual phenomenon involved in the tropical Pacific Ocean-atmosphere interactions. In this paper, an asymptotic method of solving the nonlinear equation for ...The EI Nino/La Nina-Southern Oscillation (ENSO) is an interannual phenomenon involved in the tropical Pacific Ocean-atmosphere interactions. In this paper, an asymptotic method of solving the nonlinear equation for the ENSO model is created. And based on a class of oscillator of the ENSO model, the approximate solution of a corresponding problem is studied by employing the method of homotopic mapping. It is proved from the results that the homotopic method can be used for analysing the sea surface temperature anomaly in the equatorial eastern Pacific and the thermocline depth anomaly of the atmosphere-ocean oscillation for the ENSO model.展开更多
A class of coupled system to oscillate of the E1 Nino/La Nino-Southern Oscillation (ENSO) mechanism is studied. Using the perturbed theory, the asymptotic expansions and asymptotic behavior of the solution for an EN...A class of coupled system to oscillate of the E1 Nino/La Nino-Southern Oscillation (ENSO) mechanism is studied. Using the perturbed theory, the asymptotic expansions and asymptotic behavior of the solution for an ENSO model are obtained.展开更多
A class of coupled system of the E1 Nino/La Nina-Southern Oscillation (ENSO) mechanism is studied. Using the perturbed theory, the asymptotic expansions of the solution for ENSO model are obtained and the asymptotic...A class of coupled system of the E1 Nino/La Nina-Southern Oscillation (ENSO) mechanism is studied. Using the perturbed theory, the asymptotic expansions of the solution for ENSO model are obtained and the asymptotic behavior of solution for corresponding problem is considered.展开更多
A class of delayed oscillators of El Nifio-southern oscillation (ENSO) models is considered. Using the delayed theory, the perturbed theory and other methods, the asymptotic expansions of the solutions for ENSO mode...A class of delayed oscillators of El Nifio-southern oscillation (ENSO) models is considered. Using the delayed theory, the perturbed theory and other methods, the asymptotic expansions of the solutions for ENSO models are obtained and the asymptotic behaviour of solution of corresponding problem is studied.展开更多
A class of nonlinear coupled system for EI Nino-Southern Oscillation (ENSO) model is considered. Using the asymptotic theory and method of variational iteration, the asymptotic expansion of the solution for ENSO mod...A class of nonlinear coupled system for EI Nino-Southern Oscillation (ENSO) model is considered. Using the asymptotic theory and method of variational iteration, the asymptotic expansion of the solution for ENSO models is obtained.展开更多
During recent decades, the tropical Indo-Pacific Ocean has become increasingly warmer. Meanwhile, both the northern and southern hemispheric polar vortices (NPV and SPV) have exhibited a deepening trend in boreal wi...During recent decades, the tropical Indo-Pacific Ocean has become increasingly warmer. Meanwhile, both the northern and southern hemispheric polar vortices (NPV and SPV) have exhibited a deepening trend in boreal winter. Although previous studies have revealed that the tropical Indian Ocean warming (IOW) favors an intensifying NPV and a weakening SPV, how the tropical Pacific Ocean warming (POW) influences the NPV and SPV remains unclear. In this study, a comparative analysis has been conducted through ensemble atmospheric general circulation model (AGCM) experiments. The results show that, for the Northern Hemisphere, the two warmings exerted opposite impacts in boreal winter, in that the IOW intensified the NPV while the POW weakened the NPV. For the Southern Hemisphere, both the IOW and POW warmed the southern polar atmosphere and weakened the SPV. A diagnostic analysis based on the vorticity budget revealed that such an interhemispheric difference in influences from the IOW and POW in boreal winter was associated with different roles of transient eddy momentum flux convergence between the hemispheres. Furthermore, this difference may have been linked to different strengths of stationary wave activity between the hemispheres in boreal winter.展开更多
Based on the spherical earth dislocation theory and a fault slip model of the Tohoku-Oki M_(W)9.0 earthquake,the co-seismic Coulomb failure stress changes(ΔCFS)on the northern Tanlu fault zone at depths of 0–40 km a...Based on the spherical earth dislocation theory and a fault slip model of the Tohoku-Oki M_(W)9.0 earthquake,the co-seismic Coulomb failure stress changes(ΔCFS)on the northern Tanlu fault zone at depths of 0–40 km are calculated.By comparing two sets of results from the spherical earth dislocation theory and the semi-infinite space one,the effect of earth curvature on the calculation results is analyzed quantitatively.First,we systematically summarize previous researches related to the northern Tanlu fault zone,divide the fault zone as detailed as possible,give the geometric parameters of each segment,and establish a segmented structural model of the northern Tanlu fault zone.Second,we calculate the Coulomb stress changes on the northern Tanlu fault zone by using the spherical earth dislocation theory.The result shows the Coulomb stress changes are no more than 0.003 MPa,which proves the great earthquake did not significantly change the stress state of the fault zone.Finally,we quantitatively analyze the disparities between the results of semi-infinite space dislocation theory and the spherical earth one.The average disparity between them is about 7.7%on the northern Tanlu fault zone and is 16.8%on the Fangzheng graben,the maximum disparity on this graben reaches up to 25.5%.It indicates that the effect of earth curvature can not be ignored.So it’s necessary to use the spherical earth dislocation theory instead of the semi-infinite space one to study the Coulomb stress change in the far field.展开更多
A previous modeling study about Pacific Ocean warming derived polar vortex response signals, by subtracting those in the Indian Ocean warming experiments from those in the Indo-Pacific. This approach questions the res...A previous modeling study about Pacific Ocean warming derived polar vortex response signals, by subtracting those in the Indian Ocean warming experiments from those in the Indo-Pacific. This approach questions the resemblance of such an indirectly derived response to one directly forced by Pacific Ocean warming. This is relevant to the additive nonlinearity of atmospheric responses to separated Indian and Pacific Ocean forcing. In the present study, an additional set of ensemble experiments are performed by prescribing isolated SST forcing in the tropical Pacific Ocean to address this issue. The results suggest a qualitative resemblance between responses in the derived and additional experiments. Thus, previous findings about the impact of Indian and Pacific Ocean warming are robust. This study has important implications for future climate change projections, considering the non-unanimous warming rates in tropical oceans in the 21st century. Nevertheless, a comparison of present direct-forced experiments with previous indirect-forced experiments suggests a significant additive nonlinearity between the Indian and Pacific Ocean warmings. Further diagnosis suggests that the nonlinearity may originate from the thermodynamic processes over the tropics.展开更多
As leading modes of the planetary-scale atmospheric circulation in the extratropics, the Northern Hemisphere(NH)annular mode(NAM) and Southern Hemisphere(SH) annular mode(SAM) are important components of global circul...As leading modes of the planetary-scale atmospheric circulation in the extratropics, the Northern Hemisphere(NH)annular mode(NAM) and Southern Hemisphere(SH) annular mode(SAM) are important components of global circulation, and their variabilities substantially impact the climate in mid-high latitudes. A 35-yr(1979-2013) simulation by the climate system model developed at the Chinese Academy of Meteorological Sciences(CAMS-CSM) was carried out based on observed sea surface temperature and sea ice data. The ability of CAMS-CSM in simulating horizontal and vertical structures of the NAM and SAM, relation of the NAM to the East Asian climate, and temporal variability of the SAM is examined and validated against the observational data. The results show that CAMS-CSM captures the zonally symmetric and out-of-phase variations of sea level pressure anomaly between the midlatitudes and polar zones in the extratropics of the NH and SH. The model has also captured the equivalent barotropic structure in tropospheric geopotential height and the meridional shifts of the NH and SH jet systems associated with the NAM and SAM anomalies. Furthermore, the model is able to reflect the variability of northern and southern Ferrel cells corresponding to the NAM and SAM anomalies. The model reproduces the observed relationship of the boreal winter NAM with the East Asian trough and air temperature over East Asia. It also captures the upward trend of the austral summer SAM index during recent decades. However, compared with the observation, the model shows biases in both the intensity and center locations of the NAM's and SAM's horizontal and vertical structures. Specifically, it overestimates their intensities.展开更多
This study evaluates the performance in simulating the stratospheric final warming events(SFWs)that lead to the final collapse of the stratospheric polar vortex in spring in both Southern and Northern Hemispheres(SH a...This study evaluates the performance in simulating the stratospheric final warming events(SFWs)that lead to the final collapse of the stratospheric polar vortex in spring in both Southern and Northern Hemispheres(SH and NH,respectively)based on the historical simulations provided by the Coupled Model Intercomparison Project Phases 5 and 6(CMIP5 and CMIP6,respectively).Overall,CMIP5 and CMIP6 models can reproduce the main characteristics of the occurrence of SFWs.However,the SFW onset date(SFWOD)is 7 and 9 days later than in observations in the SH and NH,respectively.Moreover,the intensity of SFWs in models is 50%to 70%of that in observations.Compared with CMIP5 models,CMIP6 models have an ameliorated capability to simulate NH SFWs.However,this improvement does not manifest as significantly earlier SFW onset,but as more intense stratospheric planetary wave activities before the SFWand as a larger interannual variability of the SFWOD.By contrast,in the SH,the capability of CMIP6 models is roughly unchanged,even deteriorated in the simulation of SFWOD and stratospheric planetary wave activities before the SFW onset.The performance of CMIP6 high-top models is better than that of lowtop models.Specifically,in the NH,high-top models are considerably improved in terms of intensity of circumpolar zonal wind around the SFWOD and stratospheric planetary wave activities before the SFW onset.In the SH,high-top models show fairly earlier SFWOD by 11 days,which is closer to observations.展开更多
In this paper, a class of coupled system for the E1 Nifio/La Nifia southern oscillation (ENSO) atmospheric physics oscillation model is considered. We propose an ENSO atmospheric physics model using a method from th...In this paper, a class of coupled system for the E1 Nifio/La Nifia southern oscillation (ENSO) atmospheric physics oscillation model is considered. We propose an ENSO atmospheric physics model using a method from the asymptotic theory. It is indicated from the results that the asymptotic method can be used for analyzing the sea surface temperature anomaly and the thermocline depth anomaly of the atmosphere-ocean oscillation for the ENSO model in the equatorial Pacific.展开更多
基金financially supported by the National Key Projects of China(2011ZX05003)the 12th Five-year Program of Petrochina(2011B-04)the State Key Laboratory of EOR
文摘The Kuqa and the Southern Junggar foreland thrust belts, which lie to the southern and northern Tianshan, respectively, were formed under a strong compressional tectonic setting. Due to the differential propagation and deformation under the control of the décollement horizon, the structural deformation styles differ in the Kuqa and Southern Junggar thrust belts. Imbricated stacking is developed in the Kuqa thrust belt, forming a piggyback imbricated pattern of faulted anticline and fault-block structural assemblage dominated by salt structures. In contrast, wedge-shaped thrusts are developed in Southern Junggar, mainly forming vertical laminated patterns of multi-wedge-structure stacks strongly influenced by the décollement horizons. The different deformation patterns and structural styles of the north and south of Tian Shan control the contrasting characteristics of hydrocarbon accumulation in the foreland thrust belts of the Kuqa and the Southern Junggar thrust belts, including the variance in the hydrocarbon trap types, pathway systems and hydrocarbon-bearing horizons. Proven by the hydrocarbon accumulation research and exploration achievements, recent exploration targets should focus on sub-salt piggyback imbricated structural patterns in the Kuqa and the deep laminated patterns in the Southern Junggar thrust belt.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 90111011 and 10471039), the National Key Basic Research Special Foundation of China (Grant Nos 2003CB415101-03 and 2004CB418304), the Key Basic Research Foundation of the Chinese Academy of Sciences (Grant No KZCX3-SW-221) and in part by E-Institutes of Shanghai Municipal Education Commission (Grant No N.E03004).
文摘A class of coupled system for the E1 Nifio-Southern Oscillation (ENSO) mechanism is studied. Using the method of variational iteration for perturbation theory, the asymptotic expansions of the solution for ENSO model are obtained and the asymptotic behaviour of solution for corresponding problem is considered.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 90111011 and 10471039), the State Key Program for Basics Research of China (Grant Nos 2003CB415101-03 and 2004CB418304), the Key Project of the Chinese Academy of Sciences (Grant No KZCX3-SW-221) and partly by E-Institutes of Shanghai Municipal Education Commission of China (Grant No N.E03004).
文摘The EI Nino/La Nina-Southern Oscillation (ENSO) is an interannual phenomenon involved in the tropical Pacific Ocean-atmosphere interactions. In this paper, an asymptotic method of solving the nonlinear equation for the ENSO model is created. And based on a class of oscillator of the ENSO model, the approximate solution of a corresponding problem is studied by employing the method of homotopic mapping. It is proved from the results that the homotopic method can be used for analysing the sea surface temperature anomaly in the equatorial eastern Pacific and the thermocline depth anomaly of the atmosphere-ocean oscillation for the ENSO model.
文摘A class of coupled system to oscillate of the E1 Nino/La Nino-Southern Oscillation (ENSO) mechanism is studied. Using the perturbed theory, the asymptotic expansions and asymptotic behavior of the solution for an ENSO model are obtained.
基金The National Natural Science Foundation of China under contract Nos 90111011 and 10471039the National Key Project for Basics Research of China under contract Nos 2003CB415101-03 and 2004CB418304+1 种基金the Knowledge Innovation Project of the Chinese Academy of Sciences under contract NO.KZCXZ-YW-Q03-08LASG State Key Laboratory Special Fund and the E-Insitutes of Shanghai Municipal Education Commission under contract NO.N.E03004
文摘A class of coupled system of the E1 Nino/La Nina-Southern Oscillation (ENSO) mechanism is studied. Using the perturbed theory, the asymptotic expansions of the solution for ENSO model are obtained and the asymptotic behavior of solution for corresponding problem is considered.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.40876010and10701023),the Main Direction Program of the Knowledge Innovation Project of Chinese Academy of Sciences(Grant No.KZCX2-YW-Q03-08)the Research and Development Special Fund for Public Welfare Industry(Meteorology)(Grant No.GYHY200806010)+3 种基金the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamic State Key Laboratory Special Fundthe Foundation of E-Institutes of Shanghai Municipal Education Commission(Grant No.E03004)the Fundamental Research Funds for the Central Universities(Grant No.2010B08-2-1)the Natural Science Foundation of Zhejiang Province.China(Grant No.Y6090164)
文摘A class of delayed oscillators of El Nifio-southern oscillation (ENSO) models is considered. Using the delayed theory, the perturbed theory and other methods, the asymptotic expansions of the solutions for ENSO models are obtained and the asymptotic behaviour of solution of corresponding problem is studied.
基金the National Natural Science Foundation of China (40676016)the National Key Project for Basics Research (2003CB415101-03+1 种基金 2004CB418304)the Key Project of the Chinese Academy of Sciences (KZCX3-SW-221)
文摘A class of nonlinear coupled system for EI Nino-Southern Oscillation (ENSO) model is considered. Using the asymptotic theory and method of variational iteration, the asymptotic expansion of the solution for ENSO models is obtained.
基金supported by the National Key Basic Research Program of China(Grants No.2010CB428602 and No. 2009CB421401)the Innovative Key Project of the Chinese Academy of Sciences(Grant No.KZCX2-YW-BR-14)the National Natural Science Foundation of China(Grant No.40775053)
文摘During recent decades, the tropical Indo-Pacific Ocean has become increasingly warmer. Meanwhile, both the northern and southern hemispheric polar vortices (NPV and SPV) have exhibited a deepening trend in boreal winter. Although previous studies have revealed that the tropical Indian Ocean warming (IOW) favors an intensifying NPV and a weakening SPV, how the tropical Pacific Ocean warming (POW) influences the NPV and SPV remains unclear. In this study, a comparative analysis has been conducted through ensemble atmospheric general circulation model (AGCM) experiments. The results show that, for the Northern Hemisphere, the two warmings exerted opposite impacts in boreal winter, in that the IOW intensified the NPV while the POW weakened the NPV. For the Southern Hemisphere, both the IOW and POW warmed the southern polar atmosphere and weakened the SPV. A diagnostic analysis based on the vorticity budget revealed that such an interhemispheric difference in influences from the IOW and POW in boreal winter was associated with different roles of transient eddy momentum flux convergence between the hemispheres. Furthermore, this difference may have been linked to different strengths of stationary wave activity between the hemispheres in boreal winter.
基金This study was supported financially by the National Key R&D Program of China(No.2018YFC1503704)the National Natural Science Foundation of China(No.41874003)。
文摘Based on the spherical earth dislocation theory and a fault slip model of the Tohoku-Oki M_(W)9.0 earthquake,the co-seismic Coulomb failure stress changes(ΔCFS)on the northern Tanlu fault zone at depths of 0–40 km are calculated.By comparing two sets of results from the spherical earth dislocation theory and the semi-infinite space one,the effect of earth curvature on the calculation results is analyzed quantitatively.First,we systematically summarize previous researches related to the northern Tanlu fault zone,divide the fault zone as detailed as possible,give the geometric parameters of each segment,and establish a segmented structural model of the northern Tanlu fault zone.Second,we calculate the Coulomb stress changes on the northern Tanlu fault zone by using the spherical earth dislocation theory.The result shows the Coulomb stress changes are no more than 0.003 MPa,which proves the great earthquake did not significantly change the stress state of the fault zone.Finally,we quantitatively analyze the disparities between the results of semi-infinite space dislocation theory and the spherical earth one.The average disparity between them is about 7.7%on the northern Tanlu fault zone and is 16.8%on the Fangzheng graben,the maximum disparity on this graben reaches up to 25.5%.It indicates that the effect of earth curvature can not be ignored.So it’s necessary to use the spherical earth dislocation theory instead of the semi-infinite space one to study the Coulomb stress change in the far field.
基金supported by the Special Fund for Meteorological Scientific Research in the Public Interest of China Meteorological Administration (Grant No. GYHY201006022)the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant Nos. KZCX2-YW-BR-14 and KZCX2-YW-Q11-03)
文摘A previous modeling study about Pacific Ocean warming derived polar vortex response signals, by subtracting those in the Indian Ocean warming experiments from those in the Indo-Pacific. This approach questions the resemblance of such an indirectly derived response to one directly forced by Pacific Ocean warming. This is relevant to the additive nonlinearity of atmospheric responses to separated Indian and Pacific Ocean forcing. In the present study, an additional set of ensemble experiments are performed by prescribing isolated SST forcing in the tropical Pacific Ocean to address this issue. The results suggest a qualitative resemblance between responses in the derived and additional experiments. Thus, previous findings about the impact of Indian and Pacific Ocean warming are robust. This study has important implications for future climate change projections, considering the non-unanimous warming rates in tropical oceans in the 21st century. Nevertheless, a comparison of present direct-forced experiments with previous indirect-forced experiments suggests a significant additive nonlinearity between the Indian and Pacific Ocean warmings. Further diagnosis suggests that the nonlinearity may originate from the thermodynamic processes over the tropics.
基金Supported by the National Natural Science Foundation of China(41775084 and 41405102)National Key Research and Development Program of China(2018YFC1505706)Basic Research Special Project of Chinese Academy of Meteorological Sciences(2019Z008)
文摘As leading modes of the planetary-scale atmospheric circulation in the extratropics, the Northern Hemisphere(NH)annular mode(NAM) and Southern Hemisphere(SH) annular mode(SAM) are important components of global circulation, and their variabilities substantially impact the climate in mid-high latitudes. A 35-yr(1979-2013) simulation by the climate system model developed at the Chinese Academy of Meteorological Sciences(CAMS-CSM) was carried out based on observed sea surface temperature and sea ice data. The ability of CAMS-CSM in simulating horizontal and vertical structures of the NAM and SAM, relation of the NAM to the East Asian climate, and temporal variability of the SAM is examined and validated against the observational data. The results show that CAMS-CSM captures the zonally symmetric and out-of-phase variations of sea level pressure anomaly between the midlatitudes and polar zones in the extratropics of the NH and SH. The model has also captured the equivalent barotropic structure in tropospheric geopotential height and the meridional shifts of the NH and SH jet systems associated with the NAM and SAM anomalies. Furthermore, the model is able to reflect the variability of northern and southern Ferrel cells corresponding to the NAM and SAM anomalies. The model reproduces the observed relationship of the boreal winter NAM with the East Asian trough and air temperature over East Asia. It also captures the upward trend of the austral summer SAM index during recent decades. However, compared with the observation, the model shows biases in both the intensity and center locations of the NAM's and SAM's horizontal and vertical structures. Specifically, it overestimates their intensities.
基金supported by the National Natural Science Foundation of China(Grant Nos.41975048,42175069)the Natural Science Foundation of Jiangsu Province(Grant No.BK20191404)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA17010105)。
文摘This study evaluates the performance in simulating the stratospheric final warming events(SFWs)that lead to the final collapse of the stratospheric polar vortex in spring in both Southern and Northern Hemispheres(SH and NH,respectively)based on the historical simulations provided by the Coupled Model Intercomparison Project Phases 5 and 6(CMIP5 and CMIP6,respectively).Overall,CMIP5 and CMIP6 models can reproduce the main characteristics of the occurrence of SFWs.However,the SFW onset date(SFWOD)is 7 and 9 days later than in observations in the SH and NH,respectively.Moreover,the intensity of SFWs in models is 50%to 70%of that in observations.Compared with CMIP5 models,CMIP6 models have an ameliorated capability to simulate NH SFWs.However,this improvement does not manifest as significantly earlier SFW onset,but as more intense stratospheric planetary wave activities before the SFWand as a larger interannual variability of the SFWOD.By contrast,in the SH,the capability of CMIP6 models is roughly unchanged,even deteriorated in the simulation of SFWOD and stratospheric planetary wave activities before the SFW onset.The performance of CMIP6 high-top models is better than that of lowtop models.Specifically,in the NH,high-top models are considerably improved in terms of intensity of circumpolar zonal wind around the SFWOD and stratospheric planetary wave activities before the SFW onset.In the SH,high-top models show fairly earlier SFWOD by 11 days,which is closer to observations.
基金Project supported by the National Natural Science Foundation of China(Grant No.40876010)the Strategic Priority Research Program-Climate Change:Carbon Budget and Relevant Issues of the Chinese Academy of Sciences(Grant No.XDA01020304)+2 种基金the Natural Science Foundation from the Education Bureau of Anhui Province,China(Grant No.KJ2011A135)the Natural Science Foundation of Zhejiang Province,China(Grant No.Y6110502)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK2011042)
文摘In this paper, a class of coupled system for the E1 Nifio/La Nifia southern oscillation (ENSO) atmospheric physics oscillation model is considered. We propose an ENSO atmospheric physics model using a method from the asymptotic theory. It is indicated from the results that the asymptotic method can be used for analyzing the sea surface temperature anomaly and the thermocline depth anomaly of the atmosphere-ocean oscillation for the ENSO model in the equatorial Pacific.