Spatial Variance Characteristics of Solar Radiation during Tobacco Growth in Henan Province

Geostatistics is a branch of statistics focusing on spatial variance.Based on analyzing climatic database of Henan province during 1950-2000,the spatial variability and distribution characteristics of solar radiation during tobacco growth are studied by using geostatistical method combined with GIS.The statistical results indicated that solar radiation mentioned above were fitted with normal distribution well,satisfying the demanding of stationary hypothesis for geostatistics.The coefficients of variation of solar radiation in May,which is 9.93%,is the greatest among tobacco growth stages;while the coefficients of variation of solar radiation in July,which is 3.87%,is the smallest among tobacco growth stages.Analysis of the isotropic variogram indicated that total solar radiation during tobacco growth was well described with gaussian model,with the distance of spatial dependence being 1997100.00m.And it was strongly spatially dependence with C0/sill being 18.45%.The Kriging method and GIS technique were applied to calculate the unobserved points and were used to generate the contour map.The area with total solar radiation during tobacco growth semivariogram in the range of 2170~2258MJ·m-2 were found in Nanyang City,Xinyang City,Luoyang City,Sanmenxiao City,and Pingdingshan City,accounting for 23.20% of the whole area.The area with total solar radiation during tobacco growth semivariogram in the range of 2258~2346MJ·m-2were found in Zhumadian city,Sanmenxiao City,Luoyang City,Pingdingshan City,Nanyang City,Xinyang City and Luoyang City,accounting for 33.07% of the whole area.The area with total solar radiation during tobacco growth semivariogram in the range of 2346~2522MJ·m-2 were found in Jiaozuo City,Hebi City,Zhoukou City,Shangqiu City,Xuchang City,Kaifeng City,Anyang City,Xinxiang City,and Puyang City,accounting for 16.65% of the whole area.