摘要
在本文中,作者统计中国东部境内降水平均绝对变率(平均绝对离差)与降水平均相对变率(平均绝对变率对于平均值的百分比).统计结果用图1—13代表之.根据分析结果,求得下列结论:(1)东北与太湖流域终年属低变率中心;(2)台湾海峡终年为高变率中心;(3)长江以南与南岭以北的江南地区大部分月份为低变率中心,但盛夏为高变率中心,此时华北与西南为低变率中心;(4)早秋西北为低变率中心;(5)成都平原冬春季(1—3月)变率特高.其次,作者用内插法计算各纬度降水相对变率的平均值(表1).作者用最小二乘方法计算年雨量与年平均降水绝对变率以及相对变率的试验关系,后者的关系为■,此处■为年平均降水相对变率,■为年平均降水量.此外,根据■计算降水变率的距常.在上式中v_(r)为观测的降水变率.在计算距常之前,曾测验过实验式配合记录的美满性.作者为计算降水变率的误差,还推求平均相对变率的均方误计算式:■,此处N为观测年数.作者也曾根据上海资料研究记录长短对于降水变率统计值的影响,结果知道:上海如有40年记录,统计降水变率就很精确.
In this paper,the author calculates the average absolute variability(the average absolute deviation)and the average relative variability(the ratio of the average absolute variability to the arithmetic mean in percentage)of precipitation in Eastern China.The results calculated are shown in Fig.1—13.According to the analysis,the following conclusions are drawn:(1)there are low variability centers throughout the year in the North-East and the areas around the Tai-hu;(2)high variability center throughout the year in the Taiwan Strait;(3)high variability center in summer but low center for the rest of the year in the areas south of the Yangtze and north of the Nanling(low centers in North China and SW China in summer);(4)low variability center in early autumn in NW China;(5)especially high variability center during the months January to March in the Chengtu Plain.Furthermore,the author computes the latitudinal averages of relative variability by virtue of interpolation(Table 1).By least squares,the author finds the empirical relations between the annual rainfalls and the annual average absolute and annual average relative variabilities of precipitation.The latter relation is given in the form:■,where ■ is the annual average relative variability of precipitation,■ the annual precipitation.In addition,the anomaly of variability is calculated by means of ■,where v_(r) is the observed variability.Before the calculation of anomalies,the goodness of fit has been tested for the empirical formula.For the purpose of calculating the error of precipitation variability,the author derives the calculation formula of the standard error of average relative variability:■,where N is the number of observations.By means of data of Shanghai,the author has also investigated the influences of durations of records on the calculated values of variability,with the result that the calculated values are sufficiently accurate,when data of 40 years long are available.
作者
么枕生
C.S.YAO(Nanking University)
出处
《气象学报》
1958年第4期225-238,共14页
Acta Meteorologica Sinica
