A coupled system of the interdecadal sea-air oscillator model is studied. The E1 Nifio-southem oscillation （ENSO） atmospheric physics oscillation is an abnormal phenomenon involved in the tropical Pacific ocean-atmo...A coupled system of the interdecadal sea-air oscillator model is studied. The E1 Nifio-southem oscillation （ENSO） atmospheric physics oscillation is an abnormal phenomenon involved in the tropical Pacific ocean-atmosphere interactions. The oscillator model is involved with the variations of both the eastern and western Pacific anomaly pat- terns. This paper proposes an ENSO atmospheric physics model using a method of the perturbation theory. The aim is to create an asymptotic solving method for the ENSO model. Employing the perturbed method, the asymptotic solution of corresponding problem is obtained, and the asymptotic behaviour of the solution is studied. Thus we can obtain the prognoses of the sea surface temperature anomaly and related physical quantities.展开更多
The rainy season precipitation in Tibet（RSPT） is a direct cause for local floods/droughts. It also indirectly affects the thermal conditions of the Tibetan Plateau, which can result in anomalous patterns of atmosphe...The rainy season precipitation in Tibet（RSPT） is a direct cause for local floods/droughts. It also indirectly affects the thermal conditions of the Tibetan Plateau, which can result in anomalous patterns of atmospheric circulation over East Asia. The interannual variability of the RSPT is often linked with the El Ni？o–Southern Oscillation（ENSO）, but the relevant mechanisms are far from being understood, particularly for different types of ENSO events. We investigated the interannual variation of the RSPT in association with different types of ENSO. A quasi-3-yr period of the RSPT（less–more–more precipitation） was significant at the 95% confidence level. A joint multi-taper method with singular value decomposition analysis of the coupled field between the RSPT and the sea surface temperature（SST）revealed that the developing eastern Pacific type El Ni？o was accompanied by a decrease in the RSPT. The shift from the central Pacific type El Ni？o to the eastern Pacific La Ni？a was accompanied by an increase in the RSPT. Weakening of the central Pacific La Ni？a was accompanied by an increase in the RSPT. Analysis of the mechanism of this coupling, using the same analysis method but other climatic factors, indicated that the gradually strengthening eastern Pacific El Ni？o can inhibit the Walker circulation, weakening the South Asian summer monsoon, and resulting in transport of less water vapor from the Bay of Bengal to Tibet. The change from the central Pacific El Ni？o to the eastern Pacific La Ni？a led to continued strengthening of the Walker circulation with westward movement of the ascending area. This enhanced the South Asian summer monsoon over the Arabian Sea and transported more water vapor to Tibet. The decreasing central Pacific La Ni？a accompanied by persistent cooling of SSTs in the equatorial Pacific led to a strong eastern North Pacific summer monsoon, causing an anomaly in the easterly transport of water vapor from the Sea of Japan to Tibet and increased RSPT.展开更多
The E1 Nifio/La Nifia Southern Oscillation （ENSO） is an interannual phenomenon involved in the tropical Pacific ocean-atmosphere interactions. In this paper, a coupled system of sea-air oscillator model is studied. ...The E1 Nifio/La Nifia Southern Oscillation （ENSO） is an interannual phenomenon involved in the tropical Pacific ocean-atmosphere interactions. In this paper, a coupled system of sea-air oscillator model is studied. The aim is to create an asymptotic solving method of nonlinear equation for the ENSO model. And based on a class of oscillators of ENSO model, employing the method of homotopic mapping, the approximate solution of corresponding problem is studied. It is proven 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 ENSO model.展开更多
On the basis of more than 200-year control run, the performance of the climate system model of Chinese Academy of Sciences （CAS-ESM-C） in simulating the E1 Nifio-Southern Oscillation （ENSO） cycle is evalu- ated, i...On the basis of more than 200-year control run, the performance of the climate system model of Chinese Academy of Sciences （CAS-ESM-C） in simulating the E1 Nifio-Southern Oscillation （ENSO） cycle is evalu- ated, including the onset, development and decay of the ENSO. It is shown that, the model can reasonably simulate the annual cycle and interannual variability of sea surface temperature （SST） in the tropical Pacif- ic, as well as the seasonal phase-locking of the ENSO. The model also captures two prerequisites for the E1 Nino onset, i.e., a westerly anomaly and a warm SST anomaly in the equatorial western Pacific. Owing to too strong forcing from an extratropical meridional wind, however, the westerly anomaly in this region is largely overestimated. Moreover, the simulated thermocline is much shallower with a weaker slope. As a result, the warm SST anomaly from the western Pacific propagates eastward more quickly, leading to a faster develop- ment of an E1 Nino. During the decay stage, owing to a stronger E1Nino in the model, the secondary Gill-type response of the tropical atmosphere to the eastern Pacific warming is much stronger, thereby resulting in a persistent easterly anomaly in the western Pacific. Meanwhile, a cold anomaly in the warm pool appears as a result of a lifted thermocline via Ekman pumping. Finally, an E1 Nino decays into a La Nina through their interactions. In addition, the shorter period and larger amplitude of the ENSO in the model can be attribut- ed to a shallower thermocline in the equatorial Pacific, which speeds up the zonal redistribution of a heat content in the upper ocean.展开更多
The relationship of the interannual variability of the transport and bifurcation latitude of the North Equatorial Current （NEC） to the E1 Nifio-Southern Oscillation （ENSO） is investigated. This is done through com...The relationship of the interannual variability of the transport and bifurcation latitude of the North Equatorial Current （NEC） to the E1 Nifio-Southern Oscillation （ENSO） is investigated. This is done through composite analysis of sea surface height （SSH） observed by satellite altimeter during October 1992-July 2009, and correspondingly derived sea surface geostrophic currents. During E1 Nifio/La Nifia years, the SSH in the tropical North Pacific Ocean falls/rises, with maximum changes in the region 0-15~N, 130~E-160~E. The decrease/increase in SSH induces a cyclonic/anticyclonic anomaly in the western tropical gyre. The cyclonic/anticyclonic anomaly in the gyre results in an increase/decrease of NEC transport, and a northward/southward shift of the NEC bifurcation latitude near the Philippine coast. The variations are mainly in response to anomalous wind forcing in the west-central tropical North Pacific Ocean, related to ENSO events.展开更多
With the observational wind data and the Zebiak-Cane model, the impact of Madden-Iulian Oscillation （MJO） as external forcing on El Nino-Southern Oscillation （ENSO） predictability is studied. The observational dat...With the observational wind data and the Zebiak-Cane model, the impact of Madden-Iulian Oscillation （MJO） as external forcing on El Nino-Southern Oscillation （ENSO） predictability is studied. The observational data are analyzed with Continuous Wavelet Transform （CWT） and then used to extract MJO signals, which are added into the model to get a new model. After the Conditional Nonlinear Optimal Perturbation （CNOP） method has been used, the initial errors which can evolve into maximum prediction error, model errors and their join errors are gained and then the Nifio 3 indices and spatial structures of three kinds of errors are investigated. The results mainly show that the observational MJO has little impact on the maximum prediction error of ENSO events and the initial error affects much greater than model error caused by MJO forcing. These demonstrate that the initial error might be the main error source that produces uncertainty in ENSO prediction, which could provide a theoretical foundation for the adaptive data assimilation of the ENSO forecast and contribute to the ENSO target observation.展开更多
A season-reliant empirical orthogonal function （S-EOF） analysis was applied to the seasonal mean SST anomalies （SSTAs） based on the HadISST1 dataset with linear trend removed at every grid point in the South Pacif...A season-reliant empirical orthogonal function （S-EOF） analysis was applied to the seasonal mean SST anomalies （SSTAs） based on the HadISST1 dataset with linear trend removed at every grid point in the South Pacific （60.5°-19.5°S, 139.5°E-60.5°W） during the period 1979-2009. The spatiotemporal characteristics of the dominant modes and their relationships with ENSO were analyzed. The results show that there are two seasonally evolving dominant modes of SSTAs in the South Pacific with interannual and interdeeadal variations; they account for nearly 40% of the total variance. Although the seasonal evolution of spatial patterns of the first S-EOF mode （S-EOF1） did not show remarkable propagation, it decays with season remarkably. The second S-EOF mode （S-EOF2） showed significant seasonal evolution and intensified with season, with distinct characteristics of eastward propagation of the negative SSTAs in southern New Zealand and positive SSTAs southeast of Australia. Both of these two modes have significant relationships with ENSO. These two modes correspond to the post-ENSO and ENSO turnabout years, respectively. The S- EOF1 mode associated with the decay of the eastern Pacific （EP） and the central Pacific （CP） types of ENSO exhibited a more significant relationship with the EP/CP type of E1 Nifio than that with the EP/CP type of La Nifia. The S-EOF2 mode contacted with the EP type of E1 Nifio changing into the EP/CP type of La Nifia showed a more significant connection with the EP/CP type of La Nifia.展开更多
In this paper a time delay equation for sea-air oscillator model is studied. The aim is to create an approximate solving method of nonlinear equation for sea-air oscillator model. Employing the method of variational i...In this paper a time delay equation for sea-air oscillator model is studied. The aim is to create an approximate solving method of nonlinear equation for sea-air oscillator model. Employing the method of variational iteration, it obtains the approximate solution of corresponding equation. This method is an approximate analytic method, which can be often used for analysing other behaviour of the sea surface temperature anomaly of the atmosphere-ocean oscillator model.展开更多
A time-delay sea-air oscillator coupling model is studied. Using Mawhin＇s continuation theorem, the result on the existence of periodic solutions for the sea-air oscillator model is obtained.
Soil temperature plays an important role in physical, biological, and microbiological processes occur- ring in the soil, but it is rarely reported as an indicator of climate change. A long-term soil temperature databa...Soil temperature plays an important role in physical, biological, and microbiological processes occur- ring in the soil, but it is rarely reported as an indicator of climate change. A long-term soil temperature database, collected in the Mojave Desert region from 1982-2000, was used to examine the relationship between regional climate change and soil temperature. During this 19-year study period, there was a warming trend in the Mojave Desert region. The soil temperature in this region, measured at 50-cm deep, increased at an average rate of 0.79℃ per decade. The temporal changes of soil temperature and those of air temperature were highly correlated. Elevation was the dominating factor that affected the spatiotemporal variations of soil and air temperature.展开更多
The South China Sea summer monsoon （SCSSM） behaves with prominent climate variability from the in- traseasonal to interdecadal time scales. On the interannual time scale, the biennial variability （so-called troposp...The South China Sea summer monsoon （SCSSM） behaves with prominent climate variability from the in- traseasonal to interdecadal time scales. On the interannual time scale, the biennial variability （so-called tropospheric biennial oscillation, TBO） is as important as the E1 Nifio-Southem Oscillation （ENSO） period. Some observed data sets, including reanalysis data, are used to explore the associated air-sea interactive physical processes and how the SCSSM TBO affects the ENSO. The results show that the shearing vorticity induced by the north Indian Ocean sea surface temperature anomalies （SSTAs） and the anomalous Philip- pine Sea anticyclone both contribute to the TBO in the SCSSM. The results also indicate that the ENSO has a weak effect on the SCSSM TBO, whereas the latter affects the ENSO to some extent.展开更多
The influence of E1 Nifio-Southern Oscillation （ENSO） on the convectively coupled Kelvin waves over the tropical Pacific is investigated by comparing the Kelvin wave activity in the eastern Pacific （EP） E1 Nifio, ...The influence of E1 Nifio-Southern Oscillation （ENSO） on the convectively coupled Kelvin waves over the tropical Pacific is investigated by comparing the Kelvin wave activity in the eastern Pacific （EP） E1 Nifio, central Pacific （CP） E1 Nifio, and La Nifia years, respectively, to 30-yr （1982 2011） mean statistics. The convectively coupled Kelvin waves in this study are represented by the two leading modes of empirical orthogonal function （EOF） of 2-25-day band-pass filtered daily outgoing longwave radiation （OLR）, with the estimated zonal wavenumber of 3 or 4, period of 8 days, and eastward propagating speed of 17 m s-1. The most significant impact of ENSO on the Kelvin wave activity is the intensification of the Kelvin waves during the EP E1 Nifios. The impact of La Nifia on the reduction of the Kelvin wave intensity is relatively weaker, reflecting the nonlinearity of tropical deep convection and the associated Kelvin waves in response to ENSO sea surface temperature （SST） anomalies. The impact of the CP E1 Nifio on the Kelvin waves is less significant due to relatively weaker SST anomalies and smaller spatial coverage. ENSO may also alter the frequency, wavelength, and phase speed of the Kelvin waves. This study demonstrates that low- frequency ENSO SST anomalies modulate high-frequency tropical disturbances, an example of weather- climate linkage.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
Seventeen coupled general circulation models from the Coupled Model Intercomparison Project Phase 5 （CMIP5） are employed to assess the relationships of interannual variations of sea surface temperature （SST） betwe...Seventeen coupled general circulation models from the Coupled Model Intercomparison Project Phase 5 （CMIP5） are employed to assess the relationships of interannual variations of sea surface temperature （SST） between the tropical Pacific （TP） and tropical Indian Ocean （TIO）. The eastern/central equatorial Pacific features the strongest SST interannual variability in the models except for the model CSIRO-Mk3-6-0, and the simulated maximum and minimum are produced by models GFDL-ESM2M and GISS-E2-H respectively. However, It remains a challenge for these models to simulate the correct climate mean SST with the warm pool-cold tongue structure in the equatorial Pacific. Almost all models reproduce E1 Nifio-Southem Oscillation （ENSO）, Indian Ocean Dipole mode （IOD） and Indian Ocean Basin-wide mode （lOB） together with their seasonal phase lock features being simulated; but the relationship between the ENSO and IOD is different for different models. Consistent with the observation, an Indian Ocean basin-wide warming （cooling） takes place over the tropical Indian Ocean in the spring following an E1 Nifio （La Nifia） in almost all the models. In some models （e.g., GFDL-ESM2G and MIROC5）, positive ENSO and IOB events are stronger than the negative events as shown in the observation. However, this asymmetry is reversed in some other models （e.g., HadGEM2-CC and HadGEM2-ES）.展开更多
Lag correlations between sea surface temperature anomalies （SSTA） in the southeastern tropical Indian Ocean （STIO） in fall and Nifio 3.4 SSTA in the eastern equatorial Pacific in the following fall are subjected t...Lag correlations between sea surface temperature anomalies （SSTA） in the southeastern tropical Indian Ocean （STIO） in fall and Nifio 3.4 SSTA in the eastern equatorial Pacific in the following fall are subjected to decadal variation, with positive correlations during some decades and negative correlations during others. Negative correlations are smaller and of shorter duration than positive correlations. Variations in lag correlations suggest that the use of the Indian Ocean Dipole （IOD） as a predictor of the E1 Nifio- Southern Oscillation （ENSO） at a lead time of one year is not effective during some decades. In this study, lag correlations between IOD and ENSO anomalies were analyzed to investigate why the IOD-ENSO teleconnection disappears during decades with negative correlations. Anomalies induced by the IOD in the equatorial Pacific Ocean during decades with negative correlations are still present, but at a greater depth than in decades with positive correlations, resulting in a lack of response to oceanic channel dynamics in the cold tongue SSTA. Lag correlations between oceanic anomalies in the west Pacific warm pool in fall and the equatorial Pacific cold tongue with a one-year time lag are significantly positive during decades with negative correlations. These results suggest that oceanic channel dynamics are overwhelmed by ocean- atmosphere coupling over the equatorial Pacific Ocean during decades with negative correlations. Therefore, the Indonesian throughflow is not effective as a link between IOD signals and the equatorial Pacific ENSO.展开更多
This paper investigates the response of the thermocline depth(TD) in the South China Sea(SCS) to the El Ni?o-Southern Oscillation(ENSO) events using 51-year(from 1960 to 2010) monthly seawater temperature and surface ...This paper investigates the response of the thermocline depth(TD) in the South China Sea(SCS) to the El Ni?o-Southern Oscillation(ENSO) events using 51-year(from 1960 to 2010) monthly seawater temperature and surface wind stress data acquired from the Simple Ocean Data Assimilation(SODA), together with heat flux data from the National Centers for Environmental Prediction(NCEP), precipitation data from the National Oceanic and Atmospheric Administration(NOAA) and evaporation data from the Woods Hole Oceanographic Institution(WHOI). It is indicated that the response of the SCS TD to the El Ni?o or La Ni?a events is in opposite phase. On one hand, the spatial-averaged TDs in the SCS(deeper than 200 m) appear as negative and positive anomalies during the mature phase of the El Ni?o and La Ni?a events, respectively. On the other hand, from June of the El Ni?o year to the subsequent April, the spatial patterns of TD in the north and south of 12°N appear as negative and positive anomalies, respectively, but present positive and negative anomalies for the La Ni?a case. However, positive and negative TD anomalies occur almost in the entire SCS in May of the subsequent year of the El Ni?o and La Ni?a events, respectively. It is suggested that the response of the TD in the SCS to the ENSO events is mainly caused by the sea surface buoyancy flux and the wind stress curl.展开更多
A coupled system of sea-air oscillator model is studied. Using the perturbed theory, the approximations of the solution for the sea-air oscillator model are obtained.
Based on the 18-year （1993-2010） National Centers for Environmental Prediction optimum interpolation sea surface temperature （SST） and simple ocean data assimilation datasets, this study investigated the patterns ...Based on the 18-year （1993-2010） National Centers for Environmental Prediction optimum interpolation sea surface temperature （SST） and simple ocean data assimilation datasets, this study investigated the patterns of the SST anomalies （SSTAs） that occurred in the South China Sea （SCS） during the mature phase of the E1 Nifio/Southem Oscillation. The most dominant characteristic was that of the out- of-phase variation between southwestern and northeastern parts of the SCS, which was influenced primarily by the net surface heat flux and by horizontal thermal advection. The negative SSTA in the northeastern SCS was caused mainly by the loss of heat to the atmosphere and because of the cold-water advection from the western Pacific through the Luzon Strait during E1 Nifio episodes. Conversely, it was found that the anomalous large-scale atmospheric circulation and weakened western boundary current during E1 Nifio episodes led to the development of the positive SSTA in the southwestern SCS.展开更多
基金Under the auspices of National Natural Science Foundation of China (No.40876010)Key Direction in Knowledge Innovation Programs of Chinese Academy of Sciences (No. KZCX2-YW-Q03-08)+2 种基金Research and Development Special Fund for Public Welfare Industry (Meteorology) (No. GYHY200806010)LASG State Key Laboratory Special Fund, Foundation of E-Institutes of Shanghai Municipal Education Commission (No.E03004)Natural Science Foundation of Education Department of Fujian Province (No.JA10288)
文摘A coupled system of the interdecadal sea-air oscillator model is studied. The E1 Nifio-southem oscillation （ENSO） atmospheric physics oscillation is an abnormal phenomenon involved in the tropical Pacific ocean-atmosphere interactions. The oscillator model is involved with the variations of both the eastern and western Pacific anomaly pat- terns. This paper proposes an ENSO atmospheric physics model using a method of the perturbation theory. The aim is to create an asymptotic solving method for the ENSO model. Employing the perturbed method, the asymptotic solution of corresponding problem is obtained, and the asymptotic behaviour of the solution is studied. Thus we can obtain the prognoses of the sea surface temperature anomaly and related physical quantities.
基金Supported by the Science and Technology Program of Tibet(Z2016R67F05)National Natural Science Foundation of China(41275097)
文摘The rainy season precipitation in Tibet（RSPT） is a direct cause for local floods/droughts. It also indirectly affects the thermal conditions of the Tibetan Plateau, which can result in anomalous patterns of atmospheric circulation over East Asia. The interannual variability of the RSPT is often linked with the El Ni？o–Southern Oscillation（ENSO）, but the relevant mechanisms are far from being understood, particularly for different types of ENSO events. We investigated the interannual variation of the RSPT in association with different types of ENSO. A quasi-3-yr period of the RSPT（less–more–more precipitation） was significant at the 95% confidence level. A joint multi-taper method with singular value decomposition analysis of the coupled field between the RSPT and the sea surface temperature（SST）revealed that the developing eastern Pacific type El Ni？o was accompanied by a decrease in the RSPT. The shift from the central Pacific type El Ni？o to the eastern Pacific La Ni？a was accompanied by an increase in the RSPT. Weakening of the central Pacific La Ni？a was accompanied by an increase in the RSPT. Analysis of the mechanism of this coupling, using the same analysis method but other climatic factors, indicated that the gradually strengthening eastern Pacific El Ni？o can inhibit the Walker circulation, weakening the South Asian summer monsoon, and resulting in transport of less water vapor from the Bay of Bengal to Tibet. The change from the central Pacific El Ni？o to the eastern Pacific La Ni？a led to continued strengthening of the Walker circulation with westward movement of the ascending area. This enhanced the South Asian summer monsoon over the Arabian Sea and transported more water vapor to Tibet. The decreasing central Pacific La Ni？a accompanied by persistent cooling of SSTs in the equatorial Pacific led to a strong eastern North Pacific summer monsoon, causing an anomaly in the easterly transport of water vapor from the Sea of Japan to Tibet and increased RSPT.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 90111011 and 10471039）, the State Key Development Program for Basic Research of China （Grant Nos 2003CB415101-03 and 2004CB418304）, the Key Project of the Chinese Academy of Sciences （Grant No KZCX3-SW-221）, in part by E-Institutes of Shanghai Municipal Education Commission （Grant No N.E03004）, and the Natural Science Foundation of Zhejiang Province, China （Grant No Y604127）.
文摘The E1 Nifio/La Nifia Southern Oscillation （ENSO） is an interannual phenomenon involved in the tropical Pacific ocean-atmosphere interactions. In this paper, a coupled system of sea-air oscillator model is studied. The aim is to create an asymptotic solving method of nonlinear equation for the ENSO model. And based on a class of oscillators of ENSO model, employing the method of homotopic mapping, the approximate solution of corresponding problem is studied. It is proven 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 ENSO model.
基金The Strategic Priority Research Program of Chinese Academy of Sciences under contract No.XDA05110201the National Basic Research Program(973 Program) of China under contract No.2010CB951901
文摘On the basis of more than 200-year control run, the performance of the climate system model of Chinese Academy of Sciences （CAS-ESM-C） in simulating the E1 Nifio-Southern Oscillation （ENSO） cycle is evalu- ated, including the onset, development and decay of the ENSO. It is shown that, the model can reasonably simulate the annual cycle and interannual variability of sea surface temperature （SST） in the tropical Pacif- ic, as well as the seasonal phase-locking of the ENSO. The model also captures two prerequisites for the E1 Nino onset, i.e., a westerly anomaly and a warm SST anomaly in the equatorial western Pacific. Owing to too strong forcing from an extratropical meridional wind, however, the westerly anomaly in this region is largely overestimated. Moreover, the simulated thermocline is much shallower with a weaker slope. As a result, the warm SST anomaly from the western Pacific propagates eastward more quickly, leading to a faster develop- ment of an E1 Nino. During the decay stage, owing to a stronger E1Nino in the model, the secondary Gill-type response of the tropical atmosphere to the eastern Pacific warming is much stronger, thereby resulting in a persistent easterly anomaly in the western Pacific. Meanwhile, a cold anomaly in the warm pool appears as a result of a lifted thermocline via Ekman pumping. Finally, an E1 Nino decays into a La Nina through their interactions. In addition, the shorter period and larger amplitude of the ENSO in the model can be attribut- ed to a shallower thermocline in the equatorial Pacific, which speeds up the zonal redistribution of a heat content in the upper ocean.
基金Supported by the National Natural Science Foundation of China Major Project (No. 40890151)the National Basic Research Program of China (973 Program) (No. 2007CB411802)
文摘The relationship of the interannual variability of the transport and bifurcation latitude of the North Equatorial Current （NEC） to the E1 Nifio-Southern Oscillation （ENSO） is investigated. This is done through composite analysis of sea surface height （SSH） observed by satellite altimeter during October 1992-July 2009, and correspondingly derived sea surface geostrophic currents. During E1 Nifio/La Nifia years, the SSH in the tropical North Pacific Ocean falls/rises, with maximum changes in the region 0-15~N, 130~E-160~E. The decrease/increase in SSH induces a cyclonic/anticyclonic anomaly in the western tropical gyre. The cyclonic/anticyclonic anomaly in the gyre results in an increase/decrease of NEC transport, and a northward/southward shift of the NEC bifurcation latitude near the Philippine coast. The variations are mainly in response to anomalous wind forcing in the west-central tropical North Pacific Ocean, related to ENSO events.
基金The National Natural Science Foundation of China under contract No.41405062
文摘With the observational wind data and the Zebiak-Cane model, the impact of Madden-Iulian Oscillation （MJO） as external forcing on El Nino-Southern Oscillation （ENSO） predictability is studied. The observational data are analyzed with Continuous Wavelet Transform （CWT） and then used to extract MJO signals, which are added into the model to get a new model. After the Conditional Nonlinear Optimal Perturbation （CNOP） method has been used, the initial errors which can evolve into maximum prediction error, model errors and their join errors are gained and then the Nifio 3 indices and spatial structures of three kinds of errors are investigated. The results mainly show that the observational MJO has little impact on the maximum prediction error of ENSO events and the initial error affects much greater than model error caused by MJO forcing. These demonstrate that the initial error might be the main error source that produces uncertainty in ENSO prediction, which could provide a theoretical foundation for the adaptive data assimilation of the ENSO forecast and contribute to the ENSO target observation.
文摘A season-reliant empirical orthogonal function （S-EOF） analysis was applied to the seasonal mean SST anomalies （SSTAs） based on the HadISST1 dataset with linear trend removed at every grid point in the South Pacific （60.5°-19.5°S, 139.5°E-60.5°W） during the period 1979-2009. The spatiotemporal characteristics of the dominant modes and their relationships with ENSO were analyzed. The results show that there are two seasonally evolving dominant modes of SSTAs in the South Pacific with interannual and interdeeadal variations; they account for nearly 40% of the total variance. Although the seasonal evolution of spatial patterns of the first S-EOF mode （S-EOF1） did not show remarkable propagation, it decays with season remarkably. The second S-EOF mode （S-EOF2） showed significant seasonal evolution and intensified with season, with distinct characteristics of eastward propagation of the negative SSTAs in southern New Zealand and positive SSTAs southeast of Australia. Both of these two modes have significant relationships with ENSO. These two modes correspond to the post-ENSO and ENSO turnabout years, respectively. The S- EOF1 mode associated with the decay of the eastern Pacific （EP） and the central Pacific （CP） types of ENSO exhibited a more significant relationship with the EP/CP type of E1 Nifio than that with the EP/CP type of La Nifia. The S-EOF2 mode contacted with the EP type of E1 Nifio changing into the EP/CP type of La Nifia showed a more significant connection with the EP/CP type of La Nifia.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 40676016, 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, China （Grant No KZCX3-SW-221）, in part by E-Institutes of Shanghai Municipal Education Commission （Grant No N.E03004） and the Natural Science Foundation of Zhejiang Province, China （Grant No Y606268）.
文摘In this paper a time delay equation for sea-air oscillator model is studied. The aim is to create an approximate solving method of nonlinear equation for sea-air oscillator model. Employing the method of variational iteration, it obtains the approximate solution of corresponding equation. This method is an approximate analytic method, which can be often used for analysing other behaviour of the sea surface temperature anomaly of the atmosphere-ocean oscillator model.
基金Project supported by the National Natural Science Foundation of China （Grant No 40676016）.
文摘A time-delay sea-air oscillator coupling model is studied. Using Mawhin＇s continuation theorem, the result on the existence of periodic solutions for the sea-air oscillator model is obtained.
基金Acknowledgements We would like to thank the professors and staff at the University of California, Riverside, who helped with this project, including Dr. Lanny Lurid, who initiated this project in the early 1980＇s Carl Nilson, who dedicated his efforts to observing the field soil temperature over the last 20 years Chris Amrhein, Dave Thomason, and Fred Ernst for their assistance in the field and in the laboratory. Recent funding for this work came from the National Natural Science Foundation of China （Grant No. 31200376） and Key Project for the Strategic Science Plan in IGSNRR, CAS （2012ZD007）.
文摘Soil temperature plays an important role in physical, biological, and microbiological processes occur- ring in the soil, but it is rarely reported as an indicator of climate change. A long-term soil temperature database, collected in the Mojave Desert region from 1982-2000, was used to examine the relationship between regional climate change and soil temperature. During this 19-year study period, there was a warming trend in the Mojave Desert region. The soil temperature in this region, measured at 50-cm deep, increased at an average rate of 0.79℃ per decade. The temporal changes of soil temperature and those of air temperature were highly correlated. Elevation was the dominating factor that affected the spatiotemporal variations of soil and air temperature.
基金The Major State Basic Research Development Program(973Program)of China under contract No.2011CB403403)
文摘The South China Sea summer monsoon （SCSSM） behaves with prominent climate variability from the in- traseasonal to interdecadal time scales. On the interannual time scale, the biennial variability （so-called tropospheric biennial oscillation, TBO） is as important as the E1 Nifio-Southem Oscillation （ENSO） period. Some observed data sets, including reanalysis data, are used to explore the associated air-sea interactive physical processes and how the SCSSM TBO affects the ENSO. The results show that the shearing vorticity induced by the north Indian Ocean sea surface temperature anomalies （SSTAs） and the anomalous Philip- pine Sea anticyclone both contribute to the TBO in the SCSSM. The results also indicate that the ENSO has a weak effect on the SCSSM TBO, whereas the latter affects the ENSO to some extent.
文摘The influence of E1 Nifio-Southern Oscillation （ENSO） on the convectively coupled Kelvin waves over the tropical Pacific is investigated by comparing the Kelvin wave activity in the eastern Pacific （EP） E1 Nifio, central Pacific （CP） E1 Nifio, and La Nifia years, respectively, to 30-yr （1982 2011） mean statistics. The convectively coupled Kelvin waves in this study are represented by the two leading modes of empirical orthogonal function （EOF） of 2-25-day band-pass filtered daily outgoing longwave radiation （OLR）, with the estimated zonal wavenumber of 3 or 4, period of 8 days, and eastward propagating speed of 17 m s-1. The most significant impact of ENSO on the Kelvin wave activity is the intensification of the Kelvin waves during the EP E1 Nifios. The impact of La Nifia on the reduction of the Kelvin wave intensity is relatively weaker, reflecting the nonlinearity of tropical deep convection and the associated Kelvin waves in response to ENSO sea surface temperature （SST） anomalies. The impact of the CP E1 Nifio on the Kelvin waves is less significant due to relatively weaker SST anomalies and smaller spatial coverage. ENSO may also alter the frequency, wavelength, and phase speed of the Kelvin waves. This study demonstrates that low- frequency ENSO SST anomalies modulate high-frequency tropical disturbances, an example of weather- climate linkage.
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supported by the National Basic Research Program of China 2012CB955602 and 2012CB955603the Natural Science Foundation of China(41176006,40921004 and 41106010)
文摘Seventeen coupled general circulation models from the Coupled Model Intercomparison Project Phase 5 （CMIP5） are employed to assess the relationships of interannual variations of sea surface temperature （SST） between the tropical Pacific （TP） and tropical Indian Ocean （TIO）. The eastern/central equatorial Pacific features the strongest SST interannual variability in the models except for the model CSIRO-Mk3-6-0, and the simulated maximum and minimum are produced by models GFDL-ESM2M and GISS-E2-H respectively. However, It remains a challenge for these models to simulate the correct climate mean SST with the warm pool-cold tongue structure in the equatorial Pacific. Almost all models reproduce E1 Nifio-Southem Oscillation （ENSO）, Indian Ocean Dipole mode （IOD） and Indian Ocean Basin-wide mode （lOB） together with their seasonal phase lock features being simulated; but the relationship between the ENSO and IOD is different for different models. Consistent with the observation, an Indian Ocean basin-wide warming （cooling） takes place over the tropical Indian Ocean in the spring following an E1 Nifio （La Nifia） in almost all the models. In some models （e.g., GFDL-ESM2G and MIROC5）, positive ENSO and IOB events are stronger than the negative events as shown in the observation. However, this asymmetry is reversed in some other models （e.g., HadGEM2-CC and HadGEM2-ES）.
基金Supported by the National Basic Research Program of China(973 Program)(Nos.2012CB956000,2011CB403502)the National Natural Science Foundation of China(No.41176019)+1 种基金the China Meteorological Administration(No.GYHY201306018)the Strategic Priority Program of Chinese Academy of Sciences(No.XDA11010301)
文摘Lag correlations between sea surface temperature anomalies （SSTA） in the southeastern tropical Indian Ocean （STIO） in fall and Nifio 3.4 SSTA in the eastern equatorial Pacific in the following fall are subjected to decadal variation, with positive correlations during some decades and negative correlations during others. Negative correlations are smaller and of shorter duration than positive correlations. Variations in lag correlations suggest that the use of the Indian Ocean Dipole （IOD） as a predictor of the E1 Nifio- Southern Oscillation （ENSO） at a lead time of one year is not effective during some decades. In this study, lag correlations between IOD and ENSO anomalies were analyzed to investigate why the IOD-ENSO teleconnection disappears during decades with negative correlations. Anomalies induced by the IOD in the equatorial Pacific Ocean during decades with negative correlations are still present, but at a greater depth than in decades with positive correlations, resulting in a lack of response to oceanic channel dynamics in the cold tongue SSTA. Lag correlations between oceanic anomalies in the west Pacific warm pool in fall and the equatorial Pacific cold tongue with a one-year time lag are significantly positive during decades with negative correlations. These results suggest that oceanic channel dynamics are overwhelmed by ocean- atmosphere coupling over the equatorial Pacific Ocean during decades with negative correlations. Therefore, the Indonesian throughflow is not effective as a link between IOD signals and the equatorial Pacific ENSO.
基金Supported by the National Basic Research Program of China(973 Program)(No.2015CB954004)the Chinese Academy of Sciences Strategic Leading Science and Technology Projects(No.XDA1102030104)the National Natural Science Foundation of China(Nos.U1405233,41176031)
文摘This paper investigates the response of the thermocline depth(TD) in the South China Sea(SCS) to the El Ni?o-Southern Oscillation(ENSO) events using 51-year(from 1960 to 2010) monthly seawater temperature and surface wind stress data acquired from the Simple Ocean Data Assimilation(SODA), together with heat flux data from the National Centers for Environmental Prediction(NCEP), precipitation data from the National Oceanic and Atmospheric Administration(NOAA) and evaporation data from the Woods Hole Oceanographic Institution(WHOI). It is indicated that the response of the SCS TD to the El Ni?o or La Ni?a events is in opposite phase. On one hand, the spatial-averaged TDs in the SCS(deeper than 200 m) appear as negative and positive anomalies during the mature phase of the El Ni?o and La Ni?a events, respectively. On the other hand, from June of the El Ni?o year to the subsequent April, the spatial patterns of TD in the north and south of 12°N appear as negative and positive anomalies, respectively, but present positive and negative anomalies for the La Ni?a case. However, positive and negative TD anomalies occur almost in the entire SCS in May of the subsequent year of the El Ni?o and La Ni?a events, respectively. It is suggested that the response of the TD in the SCS to the ENSO events is mainly caused by the sea surface buoyancy flux and the wind stress curl.
基金The research is supported by the National Natural Science Foundation of China under Grant No.90111011 and No.10471039the National Key Project for Basics Research under Grant No.2004CB418304+1 种基金the Key Project of the Chinese Academy of Sciences under Grant No.KZCX3-SW-221in part hy E-Institutes of Shanghai Municipal Education Commission under Grant No.E03004.
文摘A coupled system of sea-air oscillator model is studied. Using the perturbed theory, the approximations of the solution for the sea-air oscillator model are obtained.
基金Supported by the National Natural Science Foundation of China(No.41306026)the Scientific Research Foundation of the Third Institute of Oceanography,SOA(No.2013009)+1 种基金the National Basic Research Program of China(973 Program)(No.2011CB403504)the National Special Research Fund for Non-Profit Marine Sector(No.201005005-2)
文摘Based on the 18-year （1993-2010） National Centers for Environmental Prediction optimum interpolation sea surface temperature （SST） and simple ocean data assimilation datasets, this study investigated the patterns of the SST anomalies （SSTAs） that occurred in the South China Sea （SCS） during the mature phase of the E1 Nifio/Southem Oscillation. The most dominant characteristic was that of the out- of-phase variation between southwestern and northeastern parts of the SCS, which was influenced primarily by the net surface heat flux and by horizontal thermal advection. The negative SSTA in the northeastern SCS was caused mainly by the loss of heat to the atmosphere and because of the cold-water advection from the western Pacific through the Luzon Strait during E1 Nifio episodes. Conversely, it was found that the anomalous large-scale atmospheric circulation and weakened western boundary current during E1 Nifio episodes led to the development of the positive SSTA in the southwestern SCS.
