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Short-range Climate Prediction Experiment of the Southern Oscillation Index Based on the Singular Spectrum Analysis

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Advances in Atmospheric Sciences 2001年第5期18卷 873-881页

作者：刘健文董佩明 Beijing Aviation Institute of Meteorology Beijing China

The Southern Oscillation Index (SOI) time series is analyzed by means of the singular spectrum analysis (SSA) method with 60-month window length. Two major oscillatory pairs are found in the series whose periods are quasi-four and quasi-two years respectively. The auto-regressive model, which is developed on the basis of the Maximum Entropy Spectrum Analysis, is fitted to each of the 9 leading components including the oscillatory pairs. The prediction of SOI with the 36-month lead is obtained from the reconstruction of these extrapolated series. Correlation coefficient between predicted series and 5 months running mean of observed series is up to 0.8. The model can successfully predict the peak and duration of the strong ENSO event from 1997 to 1998. It's also shown that the proper choice of reconstructed components is the key to improve the model prediction.

关键词： Southern Oscillation Index singular spectrum analysis principal component reconstruction

Changes and spatial patterns of the differences between ground and air temperature over the Qinghai-Xizang Plateau

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Journal of Geographical Sciences 2007年第1期17卷 20-32页

作者： ZHANG Wengang LI Shuxun WU Tonghua PANG Qiangqiang The National Field Station for Scientific Observation of Cryosphere Special Environment and Disaster over the North of Qinghai-Tibet Plateau Golmud 816000 China Cold and Arid Regions Environmental and Engineering Research Institute CAS Lanzhou 730000 China

The difference between ground soil and air temperature （Ts-Ta） was studied by using the data of ground and air temperature of 99 stations over the Qinghai-Xizang （Tibet） Plateau from 1960 to 2000,and its spatial distribution and time changing tendency have been diagnosed by principal component analysis and power spectral analysis methods. The results show that the values of （Ts-Ta） are the maximum in June and the minimum in December. The first three loading eigenvectors, which reflect the main spatially anomalous structure of （Ts-Ta） over the Qinghai-Xizang Plateau, contain the contrary changing pattern between the northwestern and the southeastern regions, the pattern response of the sea level elevation and the geography, and the pattern response of the distribution of the permafrost. There are four patterns of time evolution including the patterns of monotonous increasing or decreasing trends, the basic stability pattern and the parabola pattern with the minimum value. （Ts-Ta） has a periodic variation about 2 years. According to the spatial distribution of the third loading eigenvectors of （Ts-Ta） over the Qinghai-Xizang Plateau in cold season, the permafrost response region and the seasonal frozen ground response region are identified.

关键词： Qinghai-Xizang Plateau difference between ground and air temperature (Ts-Ta) principal component temperature subarea

Evaluation of Candidate Predictors for Seasonal Precipitation Forecasting

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Atmospheric and Climate Sciences 2023年第4期13卷 539-564页

作者： Pedro M. González-Jardines Maibys Sierra-Lorenzo Adrián L. Ferrer-Hernández Arnoldo Bezanilla-Morlot Center for Atmospheric Physics Institute of Meteorology Havana Cuba

This research proposes to carry out a principal component analysis using the maximum covariance method, with the aim of finding the most robust spatio-temporal relationships between several candidate predictors and the accumulated monthly precipitation recorded in Cuba during the period 1980-2020. This process will make it possible to establish quantitative relationships that, together with theoretical considerations, make it possible to reduce the list of predictors to be used for the purpose of obtaining seasonal predictions. The values of the predictors are represented through monthly averages obtained from ERA5 reanalysis, while monthly accumulated precipitation data were obtained from a national-scope grid with 4 km of spatial resolution, used as predictand. The results obtained reflect the highest spatio-temporal correlation values with the first variability mode in all cases, indicating that the usual regime conditions are predominant and have a greater coupling with the precipitation variability in the analyzed temporal scale. In addition, they suggest that the candidates that explain the transport of moisture at low levels, as well as the gradients between the middle and lower troposphere, show the most robust associations. In the same way, the surface temperature of tropical Atlantic Sea, the flow related to Quasi-Biennial Oscillation and the thermodynamic indices, K Index and Galvez-Davison Index, present good degrees of association, for which reason they can be considered the most recommendable for carrying out forecasting experiments.

关键词： principal component Maximun Covariance Predictors ERA5

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关于纤维化奇异纤维的一些新的组合条件

Northeastern Mathematical Journal 1994年第4期10卷 503-510页

作者：唐明元

For any relative minimal fibration of gender g, we have known some basic combinatorialproperties, i. e, the necessary conditions (1)-(5) in this paper. Xiao[1] showed that these conditionsare not sufficient for g>2 and gave another two nccry conditions. In this peper, we use themethed of the Stable Reduction and the roemann-Hurtvitz formula to obtain some new combinatorialconditions. These resultS are reduced to three propeitions.

关键词： Fibration Singular Fibre Base Extension principal component

An LC Fingerprint Study of Poria cocos(Schw.)Wolf

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An LC Fingerprint Study of Poria cocos(Schw.)Wolf