基于多源数据集估算缺资料地区地表净辐射及其时空变化特征

Estimation of surface net radiation and its temporal and spatial variations in ungauged region based on multi-source data sets

本文以黄河源区为例,利用ITPCAS气象要素驱动数据集和GLASS地表反照率数据集,基于Penman-Monteith公式估算缺资料地区1979-2015年逐日地表净辐射(Rn),用GIS空间分析技术与Mann-Kendall趋势分析方法揭示其时间动态特征与空间演变规律。结果表明:1)对比ITPCAS气象要素驱动数据集和气象站数据估算的Rn,其相关系数均在0.98以上,均方根误差处于1.29～1.77之间;2)黄河源区年和四季Rn均呈下降趋势,每10年均降幅为-0.067MJ·m^(-2)·d^(-1),秋季降幅最小,春、冬降幅最大;黄河源区Rn年内呈单峰型,最大值出现在5月(14.31MJ·m^(-2)·d^(-1)),最小值出现在12月(3.34MJ·m^(-2)·d^(-1));3)年和各季节Rn值及变化趋势的空间分布相似;年平均Rn的大部分地区(91.6%)呈下降趋势,其中冬季Rn下降最明显,秋季Rn下降最不明显;4)黄河源区Rn在4 000～4 500m的区域内最大,而在4 500m以上最小;除了秋季Rn在3 500～4 000m区域外,其余季节在所有DEM分区中皆呈现下降趋势。

By using ITPCAS Meteorological Forcing Dataset and GLASS surface albedo dataset,PenmanMonteith formula was used to estimate daily surface net radiation（Rn）in ungauged region during 1979-2015,the source region of the Yellow River is taken as a case study.GIS spatial analysis technology and Mann-Kendall trend analysis method are used to reveal regional Rnspatiotemporal dynamic characteristics.The results show that 1)By comparing Rnestimated by ITPCAS Forcing Dataset with Rnestimated by weather station data,the correlation coefficients of all sites are above 0.98,with the values of root mean square error between 1.29～1.77;2)Annual/seasonal Rnvalues decline visibly with a fluctuant process in the source region of the Yellow River,with the changing rate of the annual Rnreaching 0.067MJ·m-2·d-1 every 10 years.The maximum downtrend(-0.075MJ·m-2·d-1 every 10years)is in spring and winter,while the minimum downtrend(-0.039MJ·m-2·d-1 every 10years)is in autumn.Regional mean monthly Rnhas a single peak with the maximum value(14.31MJ·m-2·d-1)in May and the minimum value(3.34MJ·m-2·d-1)in December;3)The spatial distribution of Rnvalue and annual/seasonal variation trend is similar.The annual mean Rnin the most areas（91.6%）displays a downward trend.In the seasonal scale,the decline of Rnis most obvious in winter,while in autumn it is least obvious;4)The maximum values of Rnare in the 4 000～4 500 marea,and the minimum values are in a region of more than4 500 m.Except the region of 3 500～4 000 min autumn,the rest areas in all seasons showe a downward trend.