中美半干旱区长期地表通量序列的构建及检验

基于中美半干旱区8个野外试验站点2003—2008年的观测数据,选择最小二乘法线性拟合、多项式拟合、以及双重回归拟合等方法,对NCEP再分析数据集的地表通量数据进行了系统的检验和订正。结果表明,对于日平均值,拟合订正效果相对较差,仅部分站点的土壤含水量以及地表感热和潜热通量可以使用曲线拟合的方法得以改进。对月平均值,3种方案都有不同程度的订正改进效果,订正的序列还原了数据的季节变化趋势。在此基础上,综合线性回归和曲线拟合两种方法的优势,最大程度地还原资料的线性趋势,并减小因截断误差造成的信息损失,构建了中美半干旱区长期的地表通量数据序列。所构建的半干旱区长期地表通量序列也为深入认识中美半干旱区陆气相互作用的基本特征以及模式结果验证,提供了宝贵的基础数据。

Reconstruction and validation of a long-term surface flux sequence in the semi-arid region of China and North America

Based on the observation data from 8 field stations in the semi-arid region of China and North America during 2003 to 2008, the land surface flux data in NCEP reanalysis dataset was systematically assessed and corrected with statistical methods like linear regression, curve fitting and dual regression fitting. Results show that the fitting method is not capable enough in terms of daily average value, except for soil wetness and sensible/latent heat fluxes at some individual sites. In contrast, improvements at some degree are identified in terms of monthly mean value in all the three schemes. A long-term land surface flux sequence over semi-arid regions of China and North America is established by combining the advantages of both linear regression and curve fitting methods, which can not only reflect the linear trend of the original reanalysis data but retain the diurnal and seasonal variations to a great extent at the same time. The 30 a land surface flux dataset provides a series of useful information related to the regional climatic change closely. In addition, the reconstructed long term surface dataset is beneficial to better understanding the land-atmosphere interaction and numerical model validation in this region as well.