| Based on the data of rainfall and air temperature over 160 stations in China from 1951-1998, Hadley Center monthly global SST, and NCEP/NCAR reanalysis, investigation is undertaken for the spatial-temporal variations in rainfall and air temperature in China in about 50 years and the effect of oceans. The main conclusions are as follows:(1) For the long-term mean, the rainfall shows zonal distributions from north to south with the Yangtze River as the boundary line. North of the Yangtze River the rainfall are few, south of the Yangtze River, including the South China coastal areas, the rainfall are rich. The southwest of Sichuan is also a region with relatively large precipitation. The overall trend of the coefficient of variation is gradually increased from south to north into a zonal distribution, of which the largest coefficient of variability is located in Xinjiang region and the smallest coefficient of variation is in south of the Yangtze River. This is the general climatic characteristics of rainfall. The temperature shows similar band characteristics as compared to precipitation. Temperature variabilities are largest in northeast China, northwest China and the Xinjiang region, which is due to seasonal temperature differences in the northeastern region, and the average low temperature, the temperature variation of the season. The smallest variabilities are in the South, the region of small temperature difference between seasons, and abundant rainfall.(2) The majorities of precipitation in China are not subject to normal distribution, except for a small area southwest of China. The temperature in China in general do not obey normal distribution, but in January, April, July and October, temperature in most region obey normal distribution, and the four month-state temperature distribution is subject to a broader scope than the subject of precipitation normal range of distribution.(3)For the precipitation trend coefficient in about 50 years in China, the northeast and northwest is the growth region, and in the region from the Yellow River to the southwest the precipitation has decreasing trend. The precipitation in the Yangtze River and South China also increased with time, with the largest value of about 20mm. Precipitation in the southwest is the decreased region, the greatest reduction value being the maximum -15mm. The temperature in the southwest of middle reaches of the Yangtze River decreases. North of the northeastern region of the Yellow River, the temperature increased significantly, up to 20C, and the Xinjiang region are the same. Northeast China marked regional warming temperatures in the past 50 years, with the exception of these two regions, the northwest, central and southern China in the temperature 0.50C. Generally speaking, the country's temperature is increasing(4)Precipitation in China exhibits periods of 12 months, 6 months, 4 months and 3 months, with the 12 month cycle most notably. The temperature shows 12 month and 6 month cycle, the most notable is the 12-month cycle. In the eastern part of northeast, the northwest and west-southwest, the 6-month cycle is most significantly.(5) EOF analysis of precipitation: the first principal component is the first modal pattern, this pattern reflects the south of the Yangtze River and more (less) rain, the Yangtze River and Yellow River, north and south of the Yellow River lower reaches fewer (more) rain, Type two kinds of rain, the rain-type reflects a maritime climate and non-climate differences.EOF analysis of temperature: the first mode, the upper reaches of the south of the Yangtze River is the temperature decreased (increased), other than the temperature in China is increasing (decreasing), which increased the most obvious area is the northeastern region, Northwest region is the smallest increase in area, the whole region as a whole in China is increasing the temperature characteristics. The temperature of the second mode, the mode divided by the Yellow River, south of the Yellow River is the temperature increase (lower), and the Yellow River, north of the northeast region is the temperature decreased (increased), this The temperature in the Yellow River into a reflection of different regions in China's north-south temperature differences, the Yellow River, north of the season, the Northeast regional climate changes, big temperature difference between the four seasons, the temperature of the second mode to some extent to reflect the seasonal variation of temperature in China's characteristics of regional differences. Time series from the point of view, this mode of China's regional temperature changes more obvious.SEOF precipitation analysis: the first SEOF Modal analysis of the performance of the rain belt in China from north to south to promote the four seasons. Coefficient from the time point of view, On the whole, the 60's to 70's a slight decrease in precipitation in China, after the 70s, the trend of an increase in precipitation. After the 80's, precipitation is decreasing. Analysis of precipitation SEOF second mode reflects local changes in precipitation significantly. Judging from the time series, precipitation in the 80's after the reduction in the trend.SEOF temperature analysis: the first mode of precipitation and temperature of the first modal configurations in space is better, with increased precipitation, temperature changes are moderate, low precipitation arid regions, more obvious changes in temperature. Judging from the time series, the last 50 years the temperature is low in China. China during the 20th century, 50 of China's low-temperature period, the 50's to early 60's, the temperature has increased, 60 years later to 70 in the early and entered a low-temperature period to the mid-70s to the beginning of this century, the temperature changes in the relative increased stability. The second mode of temperature reflects the past 50 years China's rising temperature is stable.(6) In terms of overall, ENSO on precipitation and temperature in China's broad scope, and this influence into a zonal distribution. ENSO on precipitation and temperature: the relevance of the region is strong in southern China, the middle zone of the Yellow River and Yangtze River in northeast China, but also a positive correlation that ENSO enhanced precipitation in the three areas increased, the temperature increased. Yangtze River Basin and the north-west, the Yellow River and north of the Xinjiang region is relatively strong negative correlation of the region shows that ENSO increased precipitation in these areas to reduce the temperature lower. IOD of China's impact on precipitation and temperature is very weak. and it is negative, It is negative that IOD makes impact in rainfall and temperature of April. It is positive that ENSO makes impact in rainfall and temperature of April(7) The composite analysis to the precipitation and temperature of 160 stations indicates the conclusion as follows:ENSO and IOD events co-occur in favor of increased precipitation in China's southwestern region, while along the southeast coast south of the Yangtze River to reduce the precipitation. Across the country (except Yunnan Province) shows the distribution of temperature is abnormal in phenomena occur. ENSO is conducive to the emergence of two rivers in the upper reaches of China's northwest, southwest regional spring warming, warming in Northeast China, the scope and moving northward. China's middle and lower reaches of the east of Two Rivers cool spring. (8)El Nino made a little westward extension for the subtropical high. Geopotential height field gradient increased divergence in southern China to maintain northwest flow in high-altitude. The vortex in southwest moves to north, and the southwest monsoon active. |
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