甘肃省历史旱涝特征与产量的关系研究

通过对甘肃省５２５年旱涝等级资料累积等级及跃变分析表明，甘肃日趋于旱化，其中，中部和河西地区最严重，陇东次之，渭水流域最小。河西，中部，陇东和渭水流域气候变化具有明显的差异性，近５２５年来中部地区气候跃变不明显。近２００年来河西地区气候跃变系数具有与陇东、渭水流域相反的变化趋势。近百年来旱涝等级资料的第一主成分有显著的３年、８年、１１年周期、第二主成分有１４年、２９年的周期。通过对主成分与近５０年

THE CLIMATIC FEATURES OF DROUGHT AND EXCESSIVE RAIN IN THE HISTORY OF GANSU AND THEIR RELATION WITH YIELDS

The accumulative total effect and climatic upspring analysis of 525\|year drought and excessive rain ranking data in Gansu shows that drought is increasing. It is severest in the western and central Gansu but Weishui area is the least inflnenced. It also shows that the climatic changes are obviously different in different parts of Gansu. The climatic upspring of the central remains dim during recent 525 years. The climatic upspring coefficient of western Gansu has the change trend opposite to those of eastern Gansu and Weishui area during recent 200 years. The first main component of recent 100 year Through drought and excessive rain ranking data has an obvious 3\|,8\|,11\|year Cyc,the second component 14\|,29\|year Cyc. Through our study their relation with 50\|year yield undulation is that the first and second main component are of minus contribution at 7\|9,2\|2.44, over 22 year Cyc and they have very close relations\|with yield undulation. The effect of drought and excessive rain is delayed about half a year except short waves. Also the analysis of accumulative total drought effect shows the relation of 525 year top grade droughts with tmies,duration,degress and influences on summer yields.