Long‐term climate variations in China and global warming signals

Abstract

[1] In this work, the authors analyze the observed long-term variations of seasonal climate in China and then investigate the possible influence of increases in greenhouse gas concentrations on these variations by comparing the observations with the simulations of the second phase of the Coupled Model Intercomparison Project (CMIP2). The long-term variations of precipitation and temperature in China are highly seasonally dependent. The main characteristic of summer precipitation in China is a drying trend in the north and a wetting trend in the central part. The precipitation in winter shows an increasing trend in southern and eastern-central China. Interesting features have also been found in the transitional seasons. In spring, precipitation variations are almost opposite to those in summer. In autumn the precipitation decreases in almost the whole country except for the middle and lower reaches of the Yangtze River Valley. In addition, the seasonality of precipitation has become slightly weaker in recent decades in southern and eastern China. Pronounced warming is observed in the entire country in winter, spring, and autumn, particularly in the northern part of China. In summer a cooling trend in central China is particularly interesting, and cooling (warming) trends generally coexist with wetting (drying) trends. The correlativity between precipitation and temperature variations is weak in spring, autumn, and winter. It has also been found that the long-term climate variations in winter and summer in China may be connected to the warming trend in the sea surface temperature of the Indian Ocean. A comparison between the observed seasonal climate variations and the CMIP2 simulations of 16 models indicates that the observed long-term variations of winter, spring, and autumn temperature in China may be associated with increases in greenhouse gas concentrations. However, such a connection is not found for the summer temperature. The tremendous uncertainties among the models in precipitation simulations make it difficult to link the precipitation variations to global warming.

Trends in Seasonal Precipitation over China during 1961-2007

“…Because our analysis is based on an updated dataset from 1961−2007, the results obtained here are somewhat different from those of earlier works based on data during 1951−2000 (Hu et al, 2003;Zhai et al, 2005). For instance, although positive trends of total winter precipitation could still be recognized over Tibet and southern China during the earlier period, the previous authors noted significant negative trends over most parts of northeast and North China in winter.…”

“…This is in agreement with earlier findings. Hu et al (2003) found that during the second half of the 20th century, drying trends appeared mainly along the mid-lower reaches of the Yangtze River, and wetting trends were found in parts of northeast and north China in spring. Zhou and Huang (2006) noticed a reverse interdecadal variation between spring and summer precipitation in northern China.…”

“…Different trends have been observed between climatic mean and extremes in China (e.g., Yan and Yang, 2000;Ma et al, 2004;Zhai et al, 2005;Qian et al, 2005). Long-term trends in mean precipitation have not been consistent for seasons with different climate regimes (Hu et al, 2003), nor for those in extremes. It is necessary to analyze seasonal precipitation and extremes separately (Zhang et al, 2001).…”

Responses of East Asian summer monsoon to historical SST and atmospheric forcing during 1950–2000

“…For example, the East Asian summer monsoon (EASM) has weakened since the late 1970s, which is characterized by the weakening of the 850 hPa southwesterly winds, southward shift of the 200 hPa jet stream, and increases in sea level pressure over East Asia (Hu 1997;Wang 2001;Guo et al 2003;Hu et al 2003;Wang and Ding 2006;Xu et al 2006). Furthermore, a cooling trend in the upper troposphere and lower stratosphere over East Asia has led to the weakening in the northward progression of southerly monsoon winds over this region Yu and Zhou 2007).…”

The regime shift in the early 1980s of spring precipitation in Korea

“…Xin et al (2006) noticed the strengthening of the droughts during late spring (20 April-20 May) since 1981 in regions near the Yangtze River. Hu et al (2003) and Zhai et al (2005) indicated the recent decreased precipitation in this region during spring. However, research results indicating the contrary have also been reported; they state that the frequency and strength of extreme precipitation in the southeast midlower reaches of the Yangtze River have increased since the early 1980s (Buda et al, 2007).…”