[Early Online Release] Responses of East Asian summer monsoon to natural and anthropogenic forcings in the 17 latest CMIP5 models----Institute of Atmospheric Physics

[Early Online Release] Responses of East Asian summer monsoon to natural and anthropogenic forcings in the 17 latest CMIP5 models

Date：2014-07-01

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Citation: Song, F., T. Zhou, and Y. Qian (2014), Responses of East Asian summer monsoon to natural and anthropogenic forcings in the 17 latest CMIP5 models, Geophys. Res. Lett.,41, doi:10.1002/2013GL058705

http://onlinelibrary.wiley.com/doi/10.1002/2013GL058705/abstract

Main Conclusions:

The observed weakening of the low-level East Asian summer monsoon circulation during 1958-2001 is partly reproduced by the all-forcing run of CMIP5 models. Among the different forcings, aerosol forcing plays a primary role in this weakening.
The preferential cooling over the eastern China caused by aerosol reduces the land-sea thermal contrast and weakens the monsoon circulation.
Although the external forcing plays a significant role in the observed weakening, it only accounts for about 25.6%.

Figure 1. The linear trends of SLP (shaded; hPa (44 year)^-1) and 850 hPa winds (vectors; m s^-1 (44 year)^-1) in JJA during 1958-2001. (a) Observations (SLP and 850 hPa winds from ERA40); (b) all-forcing run; (c) anthropogenic-forcing run; (d) GHG-forcing run; (e) natural-forcing run; (f) aerosol-forcing run from MME. The green box in (a) and (b) is northern China (32°N-42°N, 105°E-122°E).The dotted areas indicate that the precipitation trends are statistically signi？cant at the 10% level. The MME is constructed by using 35 realizations from 17 CMIP5 models (see Auxiliary Material for details).

Figure 4. (a) Scatter plot of the linear trends of SAT (K (44 year)^-1) averaged over eastern China (28°N-38°N, 105°E-122°E) and SLP (hPa (44 year)^-1) averaged over northern China (32°N-42°N, 105°E-122°E) in JJA during 1958-2001. The dots indicate 17 models in different forcing runs identified by different colors. The lines indicate the best linear fit lines between SAT and SLP. The fitting coefficients are given in the brackets; (b) Linear trends of SAT averaged over eastern China (28°N-38°N, 105°E-122°E) in the observation, all-forcing run, anthropogenic-forcing run, GHG-forcing run, aerosol-forcing run and natural-forcing run of MME (The SAT averaged over the EASM region (0°-50°N, 90°E-160°E) have been subtracted). The MME is constructed by using 35 realizations from 17 CMIP5 models (see Auxiliary Material for details).

Summary Slide Show

[video:GRL-EASM-Song-Zhou-Qian]