Wavelet Analysis of Rainfall Variation in the Yellow River Basin
SHAO Xiaomei1) XU Yuqing2) YAN Changrong3) ( 1)Key Laboratory of Land Use, Ministry of Land and Resources, China Land Surveying & Planning Institute, Beijing, 100035; 2)Department of Land Resource and Administration, College of Resources and Environment, China Agricultural University, Beijing,100094; 3) Institute of Agricultural Environment and Sustainable Development, CAAS, Beijing, 100081)
The Yellow River Basin is located in the arid and semi - arid region in the north of China, where is less river runoff and precipitation is the basis source of water resources , the basin is with seriously scarce water resources in China, even less in the world. Based on the monthly and annual rainfall data from 1961 to 2000 of 97 weather stations, the spatial structure and changes of rainfall and the multi - time scales characteristics of seasonal and annual rainfall in the past 40a in the Yellow River Basin had been analyzed using Mexican Hat wavelet analysis in this report. The periodic oscillation of rainfall variation and the points of abrupt change at different time scales along the time series are discovered and the main periods of every serial are confirmed. It was showed that the distribution of rainfall in the Yellow River Basin had obviously regional difference, which was influenced not only by the weather system but also by the geographical environment such as topography, etc; there are obvious periodic oscillation of 8-12a and 4-6a for theseasonal and annual rainfalls variation. The variation trend of the summer rainfall is similar in some degree with that of the annual rainfall and both of them have the comparable main periods. The localization characteristics of time - frequency for wavelet analysis can demonstrate the detailed structures of rainfall. The wavelet analysis can be an alternative approach to analyze climate multi-time scales characteristics and forecast short - term climate variations.