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Precipitation data from 1961 to 2000 stations starting point, combined with the NCEP / NCAR reanalysis data, APHRODITE's Asian monsoon region land precipitation data, and the Hadley Centre's SST intraseasonal oscillation (Climatology Intraseasonal state of China's precipitation climate Oscillation, CISO) and the presence of the main modes of the type to do a more detailed study. By precipitation CISO empirical orthogonal decomposition (EOF), the first main modes mainly reflect the June and July and is bounded to the north of the Yangtze River, of precipitation north-south antisymmetric spatial and temporal characteristics. Corresponding regression field corresponds to a strong period of late June, the East Asian rainy in the Arabian Sea in the east, north-central Bay of Bengal, the central part of the South China Sea, China and the Yangtze Delta of China to southern Japan convection is strong, abundant precipitation constitute the Asian summer monsoon region CISO away Related; near the ground, and the northerly airstream from the northeastern part of China to the North Pacific and southerly airstream from the South China Sea and the Philippine Sea to southern Japan Sea met in China, Jiangnan, resulting in the generation of strong convective weather in the area; and precipitation in China intraseasonal oscillation is closely linked to the weather system is a quasi-barotropic structure, the axis slightly north biased; 200hPa North China low-frequency trough of low pressure with divergent flow in front of the trough, and west of the South Asian low-frequency high-voltage southern China precipitation CISO favorable high-altitude environment. The second main modal mainly reflects the the 5,6,7 month Huaihe River basin and the South China coastal area of ??precipitation CISO inverting characteristics. The regression field circulation characterized mainly: weak Asian summer monsoon circulation, abnormal anticyclone over the East China Sea, the main factors to affect precipitation CISO. In the middle of the Arabian Sea, the Bay of Bengal in the east, central South China Sea, and China to southern Japan Sea Jiangnan convection is suppressed, the case the EASM during precipitation CISO away relevant negative phase; altitude field over the Eurasian continent from being a The north Atlantic teleconnection wave train control late June early July JAC precipitation CISO produce favorable conditions of high altitude. Chinese rainy season precipitation CISO existence of PC1 and PC2 in the physical sense can jointly reflect northward characteristics of China precipitation CISO's, therefore this paper the use of PC1 and PC2 defines a new index, and that standard will CISO oscillation significantly with the month (5 6,7) is divided into a different phase, objective analysis of China's rainy season precipitation the CISO and related elements field Temporal and spatial variations. The main conclusions are: Chinese rainy season CISO (main cycle in about 56 days), mainly in June and July, and the evolution of its spatial characteristics and EASM northward season phase-locked relationship. East Asia and the Arabian Sea and the Bay of Bengal region convection anomalies exhibit good uniformity. Convection CISO signal in the South China Sea region, in different phases, with different propagation characteristics. The first to the third phase, mainly northeast to the dissemination, in order to strengthen convection from the subtropical Pacific Northwest, the combined effect of precipitation in southeastern China; convection signal from the fourth to the sixth phase, its south equatorial regions, showing the northwest pass characteristics, eventually leading to the precipitation in the northeast region of the Indochina Peninsula, it is noteworthy that the abnormal anticyclone located over the Pacific Northwest in the fourth phase of West jump pass major factors affect the former Northwest . ISO from the South China Sea northwest of abnormal downdraft, moved south after the confluence with the exception downdraft from the island of Sumatra, and then the combined effect of convection abnormal movement and strength in the northern part of the Bay of Bengal. Abnormal high pressure 200hPa height field northeast Atlantic region abnormally high pressure 500hPa over Lake Baikal, the simultaneity of their establishment and development impact excitation of Jianghuai region precipitation in high latitudes, barotropic intraseasonal teleconnection wave train plays important role. EOF analysis of statistical significance, the master mode is mutually orthogonal, independent existence. Therefore, in the rainy season CISO the main modal PC1 and PC2 involved in this article, for example, must correspond to different circulation features of the pre-and the same period, for this paper, the main modes of CISO with an annual rainfall between 1961 and 2000 exist field to do the spatial correlation, the spatial and temporal characteristics of the annual CISO's classification obtained good correlation with the first principal mode spatial and temporal Year 7 years (1962,1964,1977,1988,1992,1995,1998) second main modal 7 years (1968,1969,1972,1975,1983,1996,1999). By synthetic analysis found that the rainy season precipitation CISO main modes occurs mainly in turn El Nino La Nina years, the Northwest Pacific in June low-altitude anticyclone strengthen favor CISO signal in the western equatorial Pacific Northwest Chuan, thereby affecting precipitation CISO signal ; second main modes occurs mainly in ENSO neutral years, more obvious seasonal characteristics of temperature anomalies of spring in Europe and West Asia region, as well as high pressure anomaly distinct seasons and enjoys pleasant North Atlantic region significantly. 5,6,7 monthly field also reflects the Western Europe and the Ural Mountains and the Pamirs temperature anomalies and geopotential height anomaly circulation features of this background affect the end of June, early July the JAC precipitation CISO inspire the barotropic Rossby wave provides excellent conditions.
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