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Large-Scale Climate Change And Drought In The Northern Of China

Posted on:2005-08-06Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y S RongFull Text:PDF
GTID:1100360152983145Subject:Science of meteorology
Abstract/Summary:PDF Full Text Request
The drought, being the most far-reaching, the most severe and the most destructible, is a kind of meteorological disasters and drought in recent years was continual and severe than the past, especially on the global climate warming background. It was important to research the change laws of drought and the future drought frequency change under the conditions of the global warming.In this dissertation the research of the drought in the northern of China was performed systematically in some ways, such as the change features of precipitation, evaporation and temperature, the drought evolution characteristics and the . relationship between the drought and large-scale climate system. My contribution is:1. The northern of China precipitation field was divided into 5 areas based on the principle of cluster analysis. The essential climatic characteristics for the 5 areas were studied systematically.2. The analyses were done in terms of the change rules of thermal and dynamical evaporation in different seasons and areas, the mechanisms of thermal and dynamical evaporation to affect the potential evaporation. A new drought index called accumulated dryness was firstly presented in order to describe the characteristics of persistence drought. The characteristics of inter-annual persistence drought could be well expressed by means of accumulated dryness. The example of the Tianjin region showed that the accumulated dryness was much more logical and well to express the persistence drought characteristics.3. Upon the 533-annual dryness and wetness grades series of the 18 stations in the northern of China, it was a 504a precipitation series from 1499 to 2002 that were firstly reconstructed by means of the Moving Cumulative Frequency Method (MCFM) and its long-term change characteristics were analyzed. It was discovered that there were multiple-time-scale quasi-periods in the reconstructing series.4. The characteristics of large-scale climatic systems on the mid-latitude and subtropics in the typical drought/flood-year and the relationship between the drought and Tibetan Plateau ground temperature field were analyzed by EOF and SVD. It wasshowed that the most outstanding signals affecting drought in the northern of China were a series of characteristics for the previous atmosphere general circulation and the change of the Tibetan Plateau ground temperature field.5. The change features of the region temperature, precipitation, evaporation and drought frequency on the global warming were studied. It was implied that the region temperature and evaporation will be higher, precipitation will be decrease and the drought frequency and extent will intensify with the increase of the global mean temperature of 1℃, 2℃ and 3℃. The researches showed that the combination of rising temperature and evaporation, deficient precipitation brought about much more severe drought.
Keywords/Search Tags:Northern of China region, drought, precipitation series, reconstruction, evaporation, accumulated dryness, ground temperature field, climate warming
PDF Full Text Request
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