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1. Introduction
Under the background of global warming, the land generally exhibits stronger warming than the ocean. The land surface temperature (LST) over Eurasia has been significantly increasing (Xu et al. 2011; Chen and Lu 2014a; Kamae et al. 2014; Dong et al. 2016, 2017). Observational analysis shows that summer warming over Eurasia presents evident spatial heterogeneity that features a zonal tripole pattern, and Northeast Asia (NEA; i.e., around Lake Baikal) experiences the most robust warming (Ito et al. 2013; Chen et al. 2016; Dong et al. 2016; Hong et al. 2017; Sato and Nakamura 2019). Land surface thermal conditions are usually closely linked to the climate, and the existing studies suggest that summer land thermal anomalies significantly impact the East Asian summer monsoon (EASM) and summer air temperature and precipitation in China (Xu et al. 2011; Zhu et al. 2012; Chen and Lu 2014a; Chen et al. 2017, 2019). Therefore, it is necessary to better understand the causes of the land surface thermal anomalies over NEA and the related climatic effects.
The possible causes of the recent NEA summer warming have been widely investigated. Studies emphasized the impacts of anomalous atmospheric circulation, especially the atmospheric teleconnection patterns, on NEA climate. It has been noted that the Silk Road pattern (SRP) along the subtropical jet waveguide (Lu et al. 2002; Kosaka et al. 2012; Hong and Lu 2016), the British–Baikal Corridor (BBC) pattern along the polar front jet (Hsu and Lin 1992; Terao 1998; Iwao and Takahashi 2008; P. Q. Xu et al. 2019), and the East Asia–Pacific (EAP) teleconnection pattern (Hirota and Takahashi 2012; Chen and Lu 2014b; Chen et al. 2016) can significantly affect the NEA summer temperature. The abnormal local circulation associated with the activity centers of these atmospheric teleconnection patterns usually influence LST directly (Schubert et al. 2011, 2014). Other studies focused on the role of the external forcing, such as sea surface temperature (SST), sea ice concentration (SIC), and the anthropogenic forcing, in recent land surface warming (Sutton et al. 2007; Ito et al. 2013; Kamae et al. 2014; Gao et al. 2015; Dong et al. 2016; He et al. 2018; Li et al. 2018; Sun et al. 2019b). For example, Hong et al. (2017) pointed out that the Atlantic...