Dominant Modes of Wintertime Upper-Tropospheric Temperature Variations over Asia and Links to Surface Climate

Abstract

In this study, the authors investigate the variations and predictability of wintertime upper-tropospheric temperature (UTT) over Asia, which are often linked to severe climate anomalies, and the associated features of large-scale circulation and surface climate. The ECMWF Interim Re-Analysis (ERA-Interim) and hindcast of the NCEP Climate Forecast System, version 2 (CFSv2), are mainly analyzed.The first empirical orthogonal function mode of UTT shows a dipole structure, with a strong positive center over southern China and a weak negative center over Mongolia. The second mode is featured by a monopole variation, with a positive center appearing from the northwestern Tibetan Plateau (TP) to Japan. The third mode exhibits a tripole pattern, with two positive centers over Pakistan and the Sea of Japan and a negative center over central Asia. The first mode is linked to El Niño-Southern Oscillation, accompanied by surface warming over the southeastern TP and deficient precipitation over southern China, the Korean Peninsula, and from equatorial East Africa to the east of the TP. The second mode is associated with circulation anomalies similar to those associated with the Arctic Oscillation, with significant warming over East Asia. The third mode features two wave trains and is linked to the Middle East jet stream, and is associated with excessive precipitation from the eastern TP to southern Japan. The CFSv2 can predict the first mode skillfully by several months in advance, but it shows little skill in predicting the second and third modes.

Response of Regional Asian Summer Monsoons to the Effect of Reduced Surface Albedo in Different Tibetan Plateau Domains in Idealized Model Experiments

“…4c). These features are overall similar with those in observations shown in many previous studies (e.g., Yang et al 2008;Jiang et al 2013b).…”

“…Previous studies (Liu and Yanai 2001;Nan et al 2009;Zhao et al 2010Zhao et al , 2011Zhao et al , 2012Zuo et al 2012Zuo et al , 2013Jiang et al 2013a) have shown a highly positive relationship between surface temperature and tropospheric temperature, here the vertically integrated temperature from 500 hPa (700 hPa if topography is below 3000 m) to 200 hPa, owing to the hydrostatic characteristics of the atmosphere. Increases in tropospheric temperature can be induced by the increase in regional heat transfer from the surface to the atmosphere (Zhao et al 2012).…”

“…Increases in tropospheric temperature can be induced by the increase in regional heat transfer from the surface to the atmosphere (Zhao et al 2012). It has also been demonstrated that TP tropospheric temperature (TPTT) more appropriately measures the large-scale heating inside the atmosphere in comparison with the relatively noisy distribution of surface temperature and thus more effectively deciphers the remote climate impact of TP thermal effect (e.g., Jiang et al 2013a). Figure 1a shows significant year-to-year variation of detrended June-August (JJA) TPTT for 1979-2016, averaged over 238-458N, 628-1058E where topography is above 1500 m. From the time series, high-value years (1981, 1984, 1998, 2006, 2013, and 2016) and low-value years (1983, 1989, 1992, 1993, 1997, 2004, 2009, and 2015) are selected using the criterion of 1 standard deviation (both positive and negative) for a composite analysis.…”

Impacts of ENSO and IOD on Snow Depth Over the Tibetan Plateau: Roles of Convections Over the Western North Pacific and Indian Ocean

“…The multiscale mountain ranges have significant impacts on atmospheric circulation, energy, and water cycles of the climate system by dynamics and thermodynamic effects (e.g., Boos & Kuang, ; Boos & Kuang, ; Yanai et al, ; Wu & Zhang, ; Wu & Liu, ; Wu, Liu et al, ). Earlier theoretical and numerical modeling studies have mainly focused on the mechanical forcing (Bolin, ; Charney & Eliassen, ; Yeh, ), while more and more attention has been paid to the thermal forcing of TP during recent decades (Yanai et al, ; Wu & Zhang, ; Duan & Wu, ; Wu et al, , 2012; Jiang et al, , , ; Wang et al, ).…”

“…While Shaman and Tziperman () proposed that ENSO affects the snow depth over the TP by exciting a stationary Rossby wave extending along the North African‐Asian jet, many previous studies have reported that ENSO could affect East Asian climate by modulating convection over the western Pacific (Chang et al, ; Lau & Nath, ; Wang et al, ). Jiang et al () found that interannual variability of wintertime surface air temperature over the southeastern TP is linked to convection anomaly over the western North Pacific (WNP), which is significantly affected by ENSO. As surface air temperature can affect snow depth/snow cover (Bao & You, ; Bojariu & Gimeno, ; Wang et al, ), is it possible that ENSO can affect snow depth/snow cover over the TP by modulating the convection over the WNP?…”