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The Extreme Heavy Precipitation Of Temporal And Spatial Distribution And Variation Characteristics Analysis In Arid Regions Of Northwest China

Posted on:2015-01-02Degree:MasterType:Thesis
Country:ChinaCandidate:L ZhaoFull Text:PDF
GTID:2250330422475398Subject:Physical geography
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Using1961-2009in northwest arid area of76stations daily precipitation andcirculation index data, the percentile method, M-K mutation testing and othermodern statistical diagnostic methods, studied in arid areas of Northwest China years,temporal and spatial distribution of seasonal precipitation and extreme heavyprecipitation and long-term changes of extreme heavy precipitation; annualprecipitation and the proportion of the volume, influence and circulation index ofextreme heavy precipitation, the study found:(1)In regional trends of annual precipitation, the rising tendency in NorthXinJiang and Tianshan Mountains is more obvious. The precipitation in the south ofXinJiang is slightly more sustained upward trend. The regions of the annualprecipitation in1980s occurred significantly mutated. In eastern Hexi-Alashan, theannual precipitation is extremely weak upward trend, and the mutation was notsignificant. In seasonal changes, the largest area of spring and summer’s averageannual precipitation is Tianshan Mountains. The autumn precipitation maximum areais the northern region, only the Hexi-Alashan region (30.81mm) in annualprecipitation is more than spring. Winter’s annual precipitation in North XinJiangregion is the largest.The spatial distribution of the average annual precipitation,higher precipitation areas are mainly concentrated in the Western TianshanMountains, north of Qilian Mountains, followed by the west of Junggar Mountain,Altai Mountain and the west of South XinJiang. Lower annual precipitation area ismainly the central and south of South XinJiang. The spatial characteristic of differentseasonal precipitation and annual precipitation is basically the same distribution.Seasonal distribution in North XinJiang region is relatively uniform, but otherdistributions of precipitation are not uniform.(2)Changing trend of extreme heavy precipitation in each region, NorthernXinJiang and Tianshan Mountains rising trend is obvious. The northwest arid area ofannual extreme heavy precipitation increasing is a mutation phenomenon in1980s,particularly from the beginning of1982. Comparative analysis of mutation andannual precipitation, the changed trend was basic consistent. But the annual extremeheavy precipitation mutation time earlier than the annual average precipitationmutation, this suggested that in response to climate change, extreme heavyprecipitation events were more active, and the annual average precipitation wascharacterized by hysteresis.(3)The change between frequency and intensity of annual average extreme heavy precipitation was basically consistent. In spatial division of the extreme heavyprecipitation frequency and intensity.XinJiang has great contact with the terrain,mainly showing high mountains, low basin characteristics. Hexi-Alasha’s frequencyand intensity of extreme heavy precipitation had consistency in space, decreaseingfrom the southeast to the northwest.(4)The extreme heavy precipitation has a strong correlation with annualprecipitation. Contribution to annual precipitation of extreme heavy precipitationalso reflecting the increasing extreme heavy precipitation is a possible objectivereasons from "warm-dry to warm and wet" transformation in the Northwest of thedrought climate.(5)Correlation between the West Pacific subtropical area index with the WestPacific subtropical intensity index and extreme heavy precipitation is the mostsignificant. In the mid1980s, spring and winter’s West Pacific subtropical area indexwas fluctuating upward trend, and the extreme heavy precipitation also changed.There is a good corresponding relationship.
Keywords/Search Tags:extreme heavy precipitation, temporal and spatial distribution, variationcharacteristics, arid regions of Northwest China
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