Recent changes in summer precipitation in Northeast China and the background circulation

Abstract

This study documents recent changes in the characteristics of summer (July-August-September) precipitation in Northeast China (NEC). A significant shift to less precipitation occurred in 1999-2012 as compared with that in 1984-1998. The reduced precipitation in the later period is closely associated with the large-scale anomalous high pressure over East Asia and anomalous descending motion over NEC. Furthermore, the significant reductions in the total cloud cover and moisture content also contribute to the reduced precipitation over NEC. To investigate the possible mechanism for the decadal shift of summer precipitation, a northeast Asian summer monsoon (NEASM) index is defined to describe the monsoon circulation over NEC. The results indicate that the NEASM has weakened since 1999 and is concurrent with the shift of the Pacific Decadal Oscillation (PDO) to the negative phase. Warming sea surface temperature (SST) in the North Pacific can zonally reduce the land-sea thermal contrast and lead to a weak NEASM. Further investigation indicates that the negative phase of the PDO has significant impacts on the atmospheric circulation associated with the NEASM. Additionally, changes in synchronous Arctic sea ice cover (SIC) also likely induce an anomalous sinking movement and weaken water vapour transport; thus, the summer precipitation over NEC decreases.

A role of the Atlantic Ocean in predicting summer surface air temperature over North East Asia?

“…In addition Kwon et al (2007) pointed out that a recent increased number of typhoons over Southern China has contributed to the upper-level circulation change through diabatic heating of the atmosphere. Precipitation has indeed changed following a shift to a dipole in precipitation anomalies: the South-Flood-North-Drought (SFND) pattern, which has emerged particularly strongly since the mid-90s (Kwon et al 2007;Qian et al 2014;Ueda et al 2015;Han et al 2015).…”

Abrupt summer warming and changes in temperature extremes over Northeast Asia since the mid-1990s: Drivers and physical processes

“…Distinguishing between forced and natural variability and understanding the drivers are an essential step in developing ond half of the 20th century, the EASM circulation underwent a weakening tendency, which was characterized by a decreasing lower-tropospheric southwesterly wind and an increasing sea level pressure (SLP) over East Asia. Associated with the weakened EASM circulation were increases in precipitation over the middle and lower reaches of the Yangtze River valley and decreases over northern China, exhibiting a so-called "southern-flood-northern-drought" (SFND) pattern (e.g., Ding et al, 2008Ding et al, , 2009Zhao et al, 2010;Huang et al, 2013;Wang et al, 2013, Zhao et al, 2014, Han et al, 2015Ueda et al, 2015). Also accompanying the weakening EASM circulation were changes in seasonal mean SAT and temperature extremes over China and a large domain of Northeast Asia, and an increase in the frequency of dry spells and droughts (Ren et al, 2010;Wei and Chen, 2011;Li et al, 2012, Qi andWang et al, 2012;Wen et al, 2013;Chen and Lu, 2014;Gao et al, 2014aGao et al, , 2014bQian et al, 2014;Song et al, 2014;Sun et al, 2014;Yang et al, 2014).…”

“…The SFND pattern and warming over Northeast Asia have emerged particularly strongly since the mid-1990s (Kwon et al, 2007;Chen and Lu, 2014;Han et al, 2015;Ueda et al, 2015). This is roughly coincident with rapid increases in aerosol emissions from China and India and decreases in aerosol emissions from North America and Europe.…”

“…This is roughly coincident with rapid increases in aerosol emissions from China and India and decreases in aerosol emissions from North America and Europe. Although previous studies have demonstrated the effects of recent decadal SST variation on decadal change in summer precipitation and surface warming over East Asia (e.g., Feng and Hu, 2008;Han et al, 2015;Ueda et al, 2015), a comprehensive and quantitative understanding of the drivers and physical processes governing the SFND pattern, and the associated changes in temperature extremes over Northeast Asia, is still lacking.…”

Nonlinear Response of Streamflow to Climate Change in High-Latitude Regions: A Case Study in Headwaters of Nenjiang River Basin in China’s Far Northeast

“…Spatial distribution of the gauge/meteorological stations and their subordination to which sub-basins are shown in Figure 1 and Table 1, respectively. Temperature and precipitation are the main driving forces to the variant streamflow in Northeast China [23,27], especially facing a warmer trend with less precipitation since 1980s [21,28]. Evapotranspiration (ET 0 ) also plays an important role in controlling the water budget over those water-deficit regions [29].…”