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221.
LIN Wan-Tao 《大气和海洋科学快报》2009,2(1):1-6
In this paper,the influence of the El NioSouthern Oscillation (ENSO) cycle on the sensitivity of nonlinear factors in the numerical simulation is investigated by conducting numerical experiments in a simple air-sea coupled model for ENSO prediction.Two sets of experiments are conducted in which zonal nonlinear factors,meridional nonlinear factors,or both are incorporated into the governing equations for the atmosphere or ocean.The results suggest that the ENSO cycle is very sensitive to the nonlinear factor of the governing equation for the atmosphere or ocean.Thus,incorporating nonlinearity into air-sea coupled models is of exclusive importance for improving ENSO simulation. 相似文献
222.
A Reconstructed Wind Stress Dataset for Climate Research over the Tropical Pacific during a 153-Year Period 下载免费PDF全文
There are close relationships between the sea surface temperature (SST) and the surface wind over the tropical Pacific.To study the past climate variability over the tropical Pacific,the long-term monthly wind stress anomalies over the tropical Pacific for the period of 1856–2008 are reconstructed with an SVD (singular value decomposition)-based statistical atmospheric model,where the wind stress anomalies are slave and directly correspond to the SST anomalies.The verification results show that the reconstructed wind stress data have high correlations and a small root mean square (RMS) error with the three reanalysis/simulated surface wind datasets from the last 50 years.In addition,the simulated SST anomalies from an intermediate oceanic model (IOM),which is forced by the reconstructed wind stress,can simulate the realistic interannual and decadal variability of the ENSO (El Nio-Southern Oscillation);this indicates that this new long-term wind stress dataset is useful for various climate studies,especially for the large-scale interannual and decadal variability. 相似文献
223.
224.
Kevin B. Jones Gregory W.L. Hodgins Miguel F. Etayo-Cadavid C. Fred T. Andrus 《Quaternary Research》2009,72(3):452-456
We quantified Δ14C, δ18O, and δ13C cycles along ontogeny within four bay scallop (Argopecten purpuratus) shells collected from Callao Bay, Salaverry, and Sechura Bay, Peru following the 1907–1908 non-El Niño years and the 1925–1926 El Niño. Δ14C and δ13C generally covary; Δ14C and δ18O vary inversely. Simultaneous decreases in Δ14C and increases in δ18O in non-El Niño shells are followed by constant Δ14C and gradually decreasing δ18O, which we interpret as evidence for discrete marine upwelling events followed by warming of the initially cold upwelled water. Upwelling changes from El Niño events are detectable with difficulty in mollusk shell Δ14C. 相似文献
225.
Heiko Paeth Anja Scholten Petra Friederichs Andreas Hense 《Global and Planetary Change》2008,60(3-4):265-288
The sensitivity of climate phenomena in the low latitudes to enhanced greenhouse conditions is a scientific issue of high relevance to billions of people in the poorest countries of the globe. So far, most studies dealt with individual model results. In the present analysis, we refer to 79 coupled ocean–atmosphere simulations from 12 different climate models under 6 different IPCC scenarios. The basic question is as to what extent various state-of-the-art climate models agree in predicting changes in the main features of El Niño-Southern Oscillation (ENSO) and the monsoon climates in South Asia and West Africa. The individual model runs are compared with observational data in order to judge whether the spatio-temporal characteristics of ENSO are well reproduced. The model experiments can be grouped into multi-model ensembles. Thus, climate change signals in the classical index time series, in the principal components and in the time series of interannual variability can be evaluated against the background of internal variability and model uncertainty.There are large differences between the individual model predictions until the end of the 21st century, especially in terms of monsoon rainfall and the Southern Oscillation index (SOI). The majority of the models tends to project La Niña-like anomalies in the SOI and an intensification of the summer monsoon precipitation in India and West Africa. However, the response barely exceeds the level of natural variability and the systematic intermodel variations are larger than the impact of different IPCC scenarios. Nonetheless, there is one prominent climate change signal, which stands out from model variations and internal noise: All forced model experiments agree in predicting a substantial warming in the eastern tropical Pacific. This oceanic heating does not necessarily lead to a modification of ENSO towards more frequent El Niño and/or La Niña events. It simply represents a change in the background state of ENSO. Indeed, we did not find convincing multi-model evidence for a modification of the wavelet spectra in terms of ENSO or the monsoons. Some models suggest an intensification of the annual cycle but this signal is fairly model-dependent. Thus, large model uncertainty still exists with respect to the future behaviour of climate in the low latitudes. This has to be taken into account when addressing climate change signals in individual model experiments and ensembles. 相似文献
226.
玉龙雪山冰川变化对ENSO事件的响应 总被引:1,自引:1,他引:0
应用独立性检验方法就ENSO事件对我国云南丽江地区降水、温度和冰川变化影响进行了相关分析. 结果表明丽江降水与ENSO事件有密切关系, MEI值为负时下一年降水量增加, MEI正值与下一年降水量减少相对应. 丽江气温与ENSO事件关系显著, MEI值为负时下一年气温降低, MEI正值与下一年气温增加对应. 利用夏季降水量和气温设计了冰川积累量指数并与MEI进行对比分析, 发现当年MEI值与下一年的冰川积累指数存在一定相关关系, 并影响未来的冰川的变化, MEI为正时冰川将会退缩, MEI值为负时冰川将会前进. 相似文献
227.
对ENSO循环机理的一些新认识 总被引:7,自引:1,他引:6
近几年国内学者通过资料诊断、理论分析和数值试验,对ENSO循环的机理提出了一些新的看法,其中包括El Nino和La Nina的起源,与ENSO循环相联系的暖、冷水的传播过程,热带西太平洋纬向风应力异常,以及热带东太平洋经向风应力异常在ENSO循环中的动力作用等.作者介绍了我国在这些方面的一些研究成果. 相似文献
228.
In south China, warm-sector rainstorms are significantly different from the traditional frontal rainstorms due to complex mechanism, which brings great challenges to their forecast. In this study, based on ensemble forecasting, the high-resolution mesoscale numerical forecast model WRF was used to investigate the effect of initial errors on a warmsector rainstorm and a frontal rainstorm under the same circulation in south China, respectively. We analyzed the sensitivity of forecast errors to the... 相似文献
229.
This paper investigates the contrasts between strong and weak Madden-Julian
Oscillation (MJO) activity over the equatorial western Pacific during winter using the NCEP
reanalysis data. It is shown that the MJO over the equatorial western Pacific in winter shows
significant interannual and interdecadal variabilities. During the winters with strong MJO
activity, an anomalous cyclonic circulation lies east of the Philippines, strong anomalous
easterlies control the equatorial eastern Pacific, and anomalous westerlies extend from the
Indian Ocean to the western Pacific in the lower troposphere, which strengthens the
convergence and convection over the equatorial western Pacific. The moisture convergence in
the lower troposphere is also enhanced over the western Pacific, which is favorable to the
activity of MJO. Eastward propagation is a significant feature of the MJO, though there is
some westward propagation. The space-time spectral power and center period of the MJO are
higher during strong MJO activity winters. The anomalous activity of MJO is closely related to
the sea surface temperature (SST) and East Asian winter monsoon (EAWM). During strong MJO
activity winters, there are positive/negative anomalies at high/low latitudes in both sea
level pressure and 500 hPa geopotential height, and the temperature is lower over the central
part of the Chinese mainland, which indicates a strong EAWM. China experiences more rainfall
between the Yellow and Yangtze Rivers, but less rainfall south of the Yangtze River. The SSTA
is negative near the Taiwan Island due to the impact of strong EAWM and shows a La Ni?a
pattern anomaly over the eastern Pacific. During the weak MJO activity winters, the situation
is reversed. 相似文献
230.
This paper investigates the possible sources of errors associated with tropical cyclone (TC) tracks forecasted using the Global/Regional Assimilation and Prediction System (GRAPES). In Part I, it is shown that the model error of GRAPES may be the main cause of poor forecasts of landfalling TCs. Thus, a further examination of the model error is the focus of Part II. Considering model error as a type of forcing, the model error can be represented by the combination of good forecasts and bad forecasts. Results show that there are systematic model errors. The model error of the geopotential height component has periodic features, with a period of 24 h and a global pattern of wavenumber 2 from west to east located between 60°S and 60°N. This periodic model error presents similar features as the atmospheric semidiurnal tide, which reflect signals from tropical diabatic heating, indicating that the parameter errors related to the tropical diabatic heating may be the source of the periodic model error. The above model errors are subtracted from the forecast equation and a series of new forecasts are made. The average forecasting capability using the rectified model is improved compared to simply improving the initial conditions of the original GRAPES model. This confirms the strong impact of the periodic model error on landfalling TC track forecasts. Besides, if the model error used to rectify the model is obtained from an examination of additional TCs, the forecasting capabilities of the corresponding rectified model will be improved. 相似文献