| Based on the60meteorological observation stations extreme precipitation dataduring the1962to2011in the north and south of the Qinling mountains, variations inspatial and temporal of8extreme precipitation index and the potential influentialfactors in the whole region and the5sub-regions were analyzed systematically, themain conclusions were as followed:(1) Quality control and Homogeneity test were used to measure the precipitationdata in the studied area. Quality control at73stations in the study area founded thatthe10stations observation time is less than one year,3stations lack of observationtime at1or5years,13stations lack of observation time more than five years, the lackof observation time at satiations more than5years were deleted, so only60stationshave been retained. Homogeneity testing of60stations suggested that only Wudustation and Xinxiang station have the mutation point in absolute test, while mutationpoint does not exist when add the reference sequences to relative test. So themutations point does not exist, there doesn’t need further correction.(2) The analysis of8extreme precipitation index in the study area founded that,the total annual precipitation reduced at the maximize, the extreme precipitationinterannual increase at the maximize, but the changes are not obvious entirety; thereare obvious interannual variations in extreme precipitation index at5sub-regions, theannual precipitation have a remarkable reducing in the loess original area, totalprecipitation and the annual average precipitation intensity have an obvious regionaldifferences, and the change has significant latitude zonality, increased from south tonorth gradually; Spatial variations of the annual average extreme precipitation indexpresent a significant "ladder" shape in north and south of the Qinling mountains,continuous without precipitation days in the south of Qinling is significantly morethan the north of Qinling, increasing from south to north gradually, and the otherindex was decreased gradually from south to north, exerts dry and wet differencesapparently. Interannual variations of the continue without precipitation days showed atrend of increase mainly concentrated in the south of Qinling, reducing trend mainlyconcentrated in the loess original area and Wushan mountainous region, the stations of total precipitation decreased in the whole study area mainly concentrated in the108°E and the north of Qinling mountains, the stations of precipitation intensityincreased are mainly concentrated in the west of105°E, spatial distribution ininterannual variations of maximum1day total precipitation, maximum5days totalprecipitation, extreme precipitation and very extreme precipitation have an similarlytendency, that made extreme precipitation at part of stations in the south of Qinlingpresent a tendency of more extremely.(3) The analysis of the potential influence factors on extreme precipitation index innorth and south of the Qinling mountains found that, variations of the extremeprecipitation index in flat area is relatively stable, the interannual change of extremeprecipitation index is larger in small and low mountain, bigger and low mountain,bigger and higher mountain, which have a largest change in bigger mountains, and theincreased or decreased of extreme precipitation events occurred mainly in suchcomplex terrain region. The strengthened westerly jet caused water vapor transportfrom the east coast to inland in china, the weaken Asian monsoon system makes theextreme precipitation events increased in south China, the block of Qinling lead tomore arid climate in the north Qinling mountains, and the climate differences furtherincreased in the north and south of the Qinling mountains. In the formation process ofthe extreme precipitation events, the complex large scale circulation systems have asignificant influence on a wide range of precipitation events, but have a little impacton small scale precipitation events. |
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