Asymmetric effects of soil moisture on mean daily maximum and minimum temperatures over eastern China
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ORIGINAL PAPER
Asymmetric effects of soil moisture on mean daily maximum and minimum temperatures over eastern China Lingyun Wu • Jingyong Zhang
Received: 18 September 2012 / Accepted: 8 September 2013 / Published online: 1 October 2013 Ó Springer-Verlag Wien 2013
Abstract This study statistically investigates the effects of soil moisture on mean daily maximum (Tmax ) and minimum temperatures (Tmin ) over eastern China in spring (from March to May), summer (from June to August) and fall (from September to November), using the Global Land Data Assimilation System (GLDAS) soil moisture and observational temperatures. The results show that soil moisture exerts asymmetric effects on Tmax and Tmin , thereby has substantial effects on the diurnal temperature range (DTR) in the three seasons. The soil moisture feedbacks on Tmax , Tmin , and DTR are found to evidently vary with season. In spring and summer, soil moisture exerts stronger negative forcing on Tmax than Tmin , and thus has negative effects on the DTR over many areas of northern China. In fall, soil moisture has much stronger positive effects on Tmin than Tmax , and thus has significant negative effects on the DTR over Northeast China and some areas of the climatic and ecological transition zone of northern China. The uncertainties in the employed data and method should be noted. Therefore, the results need to be further investigated by other data sets and methods in the future.
Responsible editor: J.-F. Miao. L. Wu (&) State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China e-mail: [email protected] J. Zhang Center for Monsoon System Research, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
1 Introduction Daily maximum (Tmax ) and minimum (Tmin ) surface air temperatures are closely tied to temperature extremes, which have attracted much attention due to their strong societal, economic, and ecological impacts. For example, record-breaking heat waves hit South China in the summer of 2003 and many areas of China in the summer of 2013, and caused catastrophic losses of property and human life, and crop failure and water shortage (e.g., Yang and Li 2005). In the fall of 2009, most areas of eastern China suffered an extraordinary cold damage, which took 33 human lives and affected 1.7 million people, and caused a large financial loss of about 1.1 billion Yuan (Chen and Fan 2010). Previous observational and model studies have presented that soil moisture can influence summertime surface air temperature (e.g., Shukla and Mintz 1982; Yeh et al. 1984; Koster et al. 2004; Seneviratne et al. 2006; Zhang et al. 2008a). In warm seasons, an increase in soil moisture can result in a high evaporation anomaly over certain regions (Budyko 1974; Eagleson 1978; Cahill et al. 1999; Koster et al. 2009). A higher evaporation tends to lead to a cooling of the overlying air (e.g., Seneviratne et al. 2006, 2010
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