Correction of Inhomogeneities in Observed Land Surface Temperatures over China
Jizeng Du, Kaicun Wang, Baoshan Cui, Shaojing Jiang
Abstract
Abstract Land surface temperature T s and near-surface air temperature T a are two main metrics that reflect climate change. Recently, based on in situ observations, several studies found that T s warmed much faster than T a in China, especially after 2000. However, we found abnormal jumps in the T s time series during 2003–05, mainly caused by the transformation from manual to automatic measurements due to snow cover. We explore the physical mechanism of the differences between automatic and manual observations and develop a model to correct the automatic observations on snowy days in the observed records of T s . Furthermore, the nonclimatic shifts in the observed T s were detected and corrected using the RHtest method. After corrections, the warming rates for T s -max , T s -min , and T s -mean were 0.21°, 0.34°, and 0.25°C decade −1 , respectively, during the 1960–2014 period. The abnormal jump in the difference between T s and T a over China after 2003, which was mentioned in existing studies, was mainly caused by inhomogeneities rather than climate change. Through a combined analysis using reanalyses and CMIP5 models, we found that T s was consistent with T a both in terms of interannual variability and long-term trends over China during 1960–2014. The T s minus T a ( T s − T a ) trend is from −0.004° to 0.009°C decade −1 , accounting for from −3.19% to 5.93% (from −3.09% to 6.39%) of the absolute warming trend of T s ( T a ).