This study reveals that, during the period 1966-2014, dust weather frequency （DWF） in northern China （north of 30°N） features two high-DWF periods, in 1966-1979 （PI） and 2000-2014 （P2）, when the linear tr...This study reveals that, during the period 1966-2014, dust weather frequency （DWF） in northern China （north of 30°N） features two high-DWF periods, in 1966-1979 （PI） and 2000-2014 （P2）, when the linear trend of DWF is removed during the study period. Here, DWF denotes the number of days of dust weather events in the spring season （March-April-May）, including dust haze, blowing dust, and dust storms, which occurred in northern China. The results show that the DWF is much higher in PI than in P2, with increased DWF distributed over southern Xinjiang, the central part of northern China. The main cause is the SST difference in the Atlantic and Pacific between the two periods. It is also found that a meridional teleconnection over East Asia in PI and a zonal wave-like pattern over Eurasia in P2 at 200 hPa play a significant role in the interannual variability in the two periods, respectively. SST over the subtropical North Atlantic （extratropical SST between the Norwegian and Barents seas） may partly contribute to the upper-level meridional （zonal） teleconnection in PI （P2）.展开更多
Understanding the regional hydrological response to varying CO_(2)concentration is critical for cost-benefit analysis of mitigation and adaptation polices in the near future. To characterize summer monsoon rainfall ch...Understanding the regional hydrological response to varying CO_(2)concentration is critical for cost-benefit analysis of mitigation and adaptation polices in the near future. To characterize summer monsoon rainfall change in East Asia in a changing CO_(2)pathway, we used the Community Earth System Model(CESM) with28 ensemble members in which the CO_(2)concentration increases at a rate of 1% per year until its quadrupling peak, i.e., 1468 ppm(ramp-up period), followed by a decrease of 1% per year until the present-day climate conditions, i.e., 367 ppm(ramp-down period). Although the CO_(2)concentration change is symmetric in time, the amount of summer rainfall anomaly in East Asia is increased 42% during a rampdown period than that during a ramp-up period when the two periods of the same CO_(2)concentration are compared. This asymmetrical rainfall response is mainly due to an enhanced El Ni?o-like warming pattern as well as its associated increase in the sea surface temperature in the western North Pacific during a ramp-down period. These sea surface temperature patterns enhance the atmospheric teleconnections and the local meridional circulations around East Asia, resulting in more rainfall over East Asia during a ramp-down period. This result implies that the removal of CO_(2)does not guarantee the return of regional rainfall to the previous climate state with the same CO_(2)concentration.展开更多
基金supported by the National Natural Science Foundation of China[grant numbers 41325018,41575079,41421004]
文摘This study reveals that, during the period 1966-2014, dust weather frequency （DWF） in northern China （north of 30°N） features two high-DWF periods, in 1966-1979 （PI） and 2000-2014 （P2）, when the linear trend of DWF is removed during the study period. Here, DWF denotes the number of days of dust weather events in the spring season （March-April-May）, including dust haze, blowing dust, and dust storms, which occurred in northern China. The results show that the DWF is much higher in PI than in P2, with increased DWF distributed over southern Xinjiang, the central part of northern China. The main cause is the SST difference in the Atlantic and Pacific between the two periods. It is also found that a meridional teleconnection over East Asia in PI and a zonal wave-like pattern over Eurasia in P2 at 200 hPa play a significant role in the interannual variability in the two periods, respectively. SST over the subtropical North Atlantic （extratropical SST between the Norwegian and Barents seas） may partly contribute to the upper-level meridional （zonal） teleconnection in PI （P2）.
基金supported by the National Research Foundation of Korea(NRF) grant(NRF-2018R1A5A1024958)。
文摘Understanding the regional hydrological response to varying CO_(2)concentration is critical for cost-benefit analysis of mitigation and adaptation polices in the near future. To characterize summer monsoon rainfall change in East Asia in a changing CO_(2)pathway, we used the Community Earth System Model(CESM) with28 ensemble members in which the CO_(2)concentration increases at a rate of 1% per year until its quadrupling peak, i.e., 1468 ppm(ramp-up period), followed by a decrease of 1% per year until the present-day climate conditions, i.e., 367 ppm(ramp-down period). Although the CO_(2)concentration change is symmetric in time, the amount of summer rainfall anomaly in East Asia is increased 42% during a rampdown period than that during a ramp-up period when the two periods of the same CO_(2)concentration are compared. This asymmetrical rainfall response is mainly due to an enhanced El Ni?o-like warming pattern as well as its associated increase in the sea surface temperature in the western North Pacific during a ramp-down period. These sea surface temperature patterns enhance the atmospheric teleconnections and the local meridional circulations around East Asia, resulting in more rainfall over East Asia during a ramp-down period. This result implies that the removal of CO_(2)does not guarantee the return of regional rainfall to the previous climate state with the same CO_(2)concentration.
