不同气象插值方法精度评估及对草地NPP估算的影响

Evaluation on Accuracy of Three Meteorological Interpolation Methods and Their Impacts on Grassland NPP Estimation

以2000—2015年宁夏境内及周边14个气象站点的年均气温及年总降水量为数据基础,分别利用反距离权重法(IDW)、样条函数法、Anusplin插值法对气象数据进行了空间插值并交叉检验,将不同方法插值获取的气象要素空间栅格数据作为模型驱动参数输入CASA模型,研究了气象要素不同插值方法对草地NPP估算精度的影响。结果表明:(1)3种插值法中Anusplin插值法在宁夏区域内气象要素插值的误差最小,精度最高,反距离权重法误差最大,在气温插值中表现最为明显;(2)通过实测数据的检验,CASA模型在宁夏草地NPP估算当中适用性强,模拟的年总NPP空间分布格局与实际情况相符,模拟数据可靠;(3)在不同草地类型的NPP估算中,引用MOD17A3NPP数据作为验证数据对比发现基于Anusplin的气象要素插值数据及CASA模型模拟的NPP一定程度上提高了NPP估算精度,其在干草原、灌丛草原、干荒漠类草原及荒漠草原的估算中精度较高,而在沼泽类和山地草甸的估算效果欠佳,其估算精度有待提高。

Based on the mean annual temperature and mean annual precipitation from 14 meteorological observation sites during 2000-2015 in Ningxia Province and its adjacent areas,three spatial interpolation methods including the inverse distance weighted interpolation(IDW),spline interpolation and Anusplin were used to interpolate the climate factors respectively.The cross checking method was used to verify the results of interpolation.Based on those results,we had been analyzed the feasibility of CASA model in estimating grassland NPP and the effects of improving interpolate precision on NPP estimation in Ningxia.The main conclusions are as follows.(1)Anusplin method had minimum error and the highest accuracy of interpolating meteorological factors in Ningxia area.IDW method′s interpolating error was the maximum,especially in air temperature interpolation.(2)The CASA model has shown the strong applicability grassland NPP estimating by comparing with the measured data and the spatial distribution pattern of NPP is consistent with the actual situation in Ningxia,therefore,the simulation data are reliable.(3)In NPP estimation of different grassland types,CASA model based on Anusplin interpolation that enhances interpolation accuracy has the little estimating error and improves the precision of NPP estimation by referencing to MOD17A3 NPP data as a verified data.The results indicate that CASA model has more accurate in estimation of NPP of semi-arid grassland,shrub grassland,shrub grassland,desert grassland and desert steppe,and the estimation accuracies of NPP of wetland grassland and mountain meadow are poor,and these estimation accuracies should be further improved.