近58年来宁夏可利用降水量多时间尺度变化特征分析

依据宁夏1951—2008年月降水及气温资料,计算了可利用降水序列。运用地统计方法、小波分析法及气候趋势系数等方法分析了宁夏近58年来可利用降水量的空间分布及多时间尺度变化特征。结果表明,宁夏多年平均可利用降水量68.5mm,自北向南依次增大;7—9月占全年的69.14%～77.48%;夏季可利用降水量占年值57.81%～67.44%,秋季次之(19.87%～27.27%),冬季最小;存在3年、6年与10年振荡周期;未来,宁夏大部分地区陆面蒸发呈增加趋势,增幅0.516～6.796mm/10a,且自北向南依次增大;各地年、夏季及秋季可利用降水量均呈减少趋势,中部干旱带减幅最大(9.839～15.779mm/10a),北部引黄灌区以5.784～8.477mm/10a幅度减少,南部山区则以6.741～8.229mm/10a的幅度减少。

Analysis of Multi-time Scale Variability of Available Precipitation for 58 Years in Ningxia

Using geostatistical approach,morlet wavelet analysis and climatic trend coefficient method,the characteristics of multi-time scale variability of available precipitation and trend were analyzed by the monthly precipitation series and temperature in Ningxia during 1951—2008.Results indicate that: In Ningxia,the average of available precipitation was 68.5 mm,and increased from north to south generally.The maximum value appears from July to September and the ratio is 69.14%~77.48% in annual.The ratios were different for seasonal available precipitation to annual,for example,the value is 57.81%~67.44%,19.87%~27.27% and 0.50%~1.24% in summer,autumn and winter respectively.The series of annual available precipitation have 3,6 and 10 years main cycles.In the future,the continental evapotranspiration will increase from north to south by 0.516~6.796 mm/10a in mostly areas of Ningxia.Moreover,the available precipitation have an induce tendency in annual,summer and autumn.The decrease ranges are 9.839~15.779 mm/10a,5.784~8.477 mm/10a and 6.741~8.229 mm/10a in the mid arid zone,the Yellow river irrigation area and south mountainous areas respectively.