Finally , a qualitative graded prediction model - markov chain qualitative modeling , is established for above two precipitation series by using meteorological graded division criteria . the forecasting result is good 论文最后还对年降水量、汛期雨量序列探讨做分级预测，采用气象分级办法进行分级。结果表明所建立的马尔柯夫预测模型具有较高精度。
Based on rs and gis technology , five indices , including vegetation index , altitude , land - using , accumulated temperature and annual rainfall , were drawn and applied to evaluate natural environment of the research region 在rs和gis支持下，提取海拔高度、植被覆盖、土地利用、年积温和年降水量等5项指标，用于评价研究区的自然环境，评价结果和实际情况基本一致。
In order to improve further the prediction accuracy of the series studied , a tar model is also used to make the prediction . although the calculation of tar model is complicated , the result of forecasting is better than the others 门限自回归模型的建模方法比较复杂，但预测精度比前面几种方法有较大提高，该模型对年降水量、汛期雨量预测合格率达90以上。
It can germinate at 0 ? and develop at 3 - 5 c even suffer from chilliness of - 21 c . at the fifth or sixth year , it ablooms at july , fruits at august or september . when the seeds are scattered by wind , the plant turn to death 其自然生长环境的土壤偏酸性，有机质含量极低，气候多变，最高月平均温度3 5 ，最低月平均温- 19 - 21 ，年降水量800mm ，无霜期仅有50d左右。
Precipitation of 500mm per year is boundary for rftfop in northwest china . the farmland where precipitation is more than 500mm , or between 400 - 500mm , or below 400mm , correspondingly , is returned to forestry , to shrubbery and to pasture 西北地区退耕还林还草以年降水量500mm为分界线，大于500mm的区域以还林为主， 400 500mm区域以造灌木林为主，小于400mm还草为主。
Eurasia , north america , antarctica has significant interdecadal change of the flood / drought during djf . global has a significant contrast of rainfall between flood / drought years . the correlations among six large - scale areas precipitation are analysed 大尺度区域中：欧亚大陆、北美洲、南极大陆旱涝年的分布有明显的年代际特征，并指出全球大部分地区的旱涝年降水量有显著的差异。
2 . with the method of multiple point regression , a general formula was established to estimate the annual precipitation at different elevation . rr = 1056 . 9 + luhzr in the equation : r x is the increasing rate of annual precipitation , and unit is mm / m 根据多点回归建立起估算区境任一海拔高度年降水量的通式： rz = 1056 . 9 + r hz r式中： r为需要计算点年降水量的垂直递增率，单位为mm / m 。
In recent 44 years , the trends of the precipitation in characteristic period of time and annual precipitation in different regions are significant . in some regions , the trend of the precipitation in characteristic period of time can denote the trend of annual precipitation 近44年来，各区域特征时段降水量和年降水量有各自的变化趋势，在某些区域，可以用特征时段降水量的变化趋势表示年降水量的变化趋势。
Except haiyuan and yanchi counties , which are 83 % , a bit lower than the theoretical probability value of 84 . 13 % , the rainfall of other five counties is larger than the theoretical probability value . this indicates that , within certain rainfall range , the annual rainfall is much stable 从实际的40年降水资料看，可近似估计该区降水量( x ? 1s ) mm的出现频率大于84 . 13 ，表明在一定的降水量范围内，其年降水量又有一定的稳定性。
The precipitation frequencies is analysed according to 1956 ~ 2000 years of rainfall record series in baoding area . the features of distribution of rainfall are detailed evaluated . firstly , the distribution of monthly precipitation is not even . for instance . the annual rainfall amount is about 548mm in whole year , about 80 % of them in summer season . secondly , yearly variation of rainfall is greater . thirdly , the abundant years usually are followed by short years , but the important changes have taken place in the last decades . before 70 ' s the abundant years took the dominant position , from the 70 ' s to the middle of 80 ' s the short years took place more frequently than ever . after the later of 80 ' s , the short years hold the main position . the above knowledge is instructive for guiding the rainwater resources effective utilization 本文利用1956 2000年保定市的长系列降雨资料，对保定市降水量进行了频率分析、年内变化分析和多年变化分析，明确了保定市降水量年内、年际间的变化情况：保定市降水量年内分配不均，汛期( 6 - 9月)占年降水量的81 。保定市降水量年际间变化大，丰水年和枯水年交替发生， 70年代以前以丰水年段为主； 70年代到80年代前期降水量丰枯交替频繁，总的接近于枯水年段； 80年代后期至今以枯水年段为主。这种降水分布规律对农业生产雨水资源的高效利用具有重要的指导意义。
