Land surface air temperature variations over Eurasia and possible causes in the past century

• Published in: International journal of climatology Vol. 38; no. 4; pp. 1925 - 1937
• Main Authors: Zuo, Zhiyan, Yang, Song, Xu, Kang, Zhang, Renhe, He, Qiong, Zhao, Tianbao, Cong, Jing
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 30.03.2018; Wiley Subscription Services, Inc
• Subjects: Aerodynamics; Air temperature; Climate system; Computational fluid dynamics; Computer simulation; Decadal variations; Deceleration; Dipoles; Dynamics; Eurasia; Fluid dynamics; Gases; Geophysical fluids; Geophysics; Greenhouse effect; Greenhouse gases; Hydrodynamics; Interactions; inter‐annual to decadal variations; land surface air temperature; Long-term changes; multi‐decadal variation; Natural gas; Regions; Robustness; Surface temperature; Surface-air temperature relationships; Temperature; Temperature variations; Time; Trends; Variation; warming; Eurasia; China; Siberia
• ISSN: 0899-8418; 1097-0088
• DOI: 10.1002/joc.5306

ABSTRACT In this study, the variations of annual land surface air temperature (SAT) over Eurasia and the northern part of Africa (0°–180°E, 0°–90°N) were investigated using monthly SAT data from the Climatic Research Unit, University of East Anglia for 1901–2014 and the simulations from the Geophysical Fluid Dynamics Laboratory coupled model. The observed results suggested that the SAT variations exhibited robust non‐uniform spatial features at multi‐time scales. For the variations in inter‐annual to decadal time scales (IDV), the intensity generally increased from south to north, with the strongest intensity being around Siberia and four times that of the weakest intensity found around China. The IDV leading pattern showed a north–south dipole across 40°N. The simulated results suggested that the north–south dipole and the northwards increase of the IDV were due to internal interactions within the complex nonlinear climate system, but the natural and greenhouse gas forcings could intensify the IDV. The warming trend of the SAT was generally homogeneous, but it showed distinctive multi‐decadal fluctuations in different regions. The linear secular trends and robust multi‐decadal variation around Siberia and China corresponded to the considerable acceleration and deceleration in the warming over the two regions, respectively. The warming around Siberia was mainly caused by greenhouse gases but its modulation due to natural forcing was also considerable because of the robust multi‐decadal variations. Around China, the multi‐decadal variation, contributed by the natural forcing, can explain more than half the variances in the warming. The warming trend around central Asia was intense and parabolic, and the multi‐decadal variation over there was weak and showed few modulating effects. This study disclosed (1) the considerable effect of multi‐decadal variations on the warming trend around Siberia and China. (2) The internal interactions within the complex nonlinear climate system lead to a south–north dipole pattern of Eurasian land surface air temperature in inter‐annual to decadal time scales. (a) Multi‐decadal variations, (b) secular trends and (c) the sum of multi‐decadal variations and secular trends derived from EEMDs of the surface air temperature around Siberia (red), China (blue) and Central Asia (green).