Analysis Of Anomaly Characteristics On Extreme Temperature And Extreme Precipitation Over Chongqing During 1961-2006

Based on 1961-2006 daily temperature data of 31 observational stations and daily precipitation data of 33 stations in Chongqing, by defining extreme rainfall threshold with the most popular international percentile method and the application of the extreme temperature and precipitation indexes announced by WMO, the spatial and temporal variation of the extreme temperature, precipitation and the precipitation in flood seasons are analyzed. The main conclusions are summarized as follows:(1) The average yearly lowest temperature and average winter lowest temperature have the most obvious trend of escalation, and adopt the significance examination in Chongqing yearly, seasonal average highest and lowest temperature.(2) Cold night, warm night, cold day and warm day indexes in Chongqing are in close range, their spatial distributions are in very similar. The high value areas of indexes are central, south-southwest, and the Yangtze River Basin in the eastern region.(3) Cold indexes (including cold night and cold day indexes) in every district are in downtrend, and the cold night of index adopted the significance examination. But warm indexes(including warm night and warm day indexes) are first in down trend then uptrend, from linear trend, the warm indexes are in upward trend in the south-east and the north side Northwest, downward trend for the rest areas.(4)The periodic oscillation of every extrme temperature index are dominated by ~4yearly period with big amplitude before the mid-1970s, 4~5 yearly oscillationexcept warm day index after 1990s.(5)The spatial distribution of every extreme precipitation index is significantdifferernt, the value of indexes are big and in upward trend in north-northwest,southeast and north-northeast regions in Chongqing.(6)The extreme rainfall in flood season is of the significant spatialdistribution, and the consistently abnormal characteristic is the main spatialmode.(7)The extreme rainfall in flood season covers a very large proportion of the totalrainfall in every region, and from a long-term trend, the extreme precipitation inflood season in Chongqing has no significant difference in the recent 46 years.(8)The periodic oscillation of extreme precipitation and the extreme precipitationindexes are not well consistent in every region, dominated by 2-3 yearly, 4-5 yearlyperiods, and about 11 yearly oscillation.