The responses of the Arctic Oscillation(AO) to global black carbon(BC) and BC emitted from major regions were compared using the atmospheric general circulation model Geophysical Fluid Dynamics Laboratory(GFDL) atmosp...The responses of the Arctic Oscillation(AO) to global black carbon(BC) and BC emitted from major regions were compared using the atmospheric general circulation model Geophysical Fluid Dynamics Laboratory(GFDL) atmospheric general circulation model(AGCM) Atmospheric Model version 2.1(AM2.1). The results indicated that global BC could induce positive-phase AO responses, characterized by negative responses over the polar cap on 500 h Pa height fields, and zonal mean sea level pressure(SLP) decreasing while zonal wind increasing at 60°, with the opposite responses over midlatitudes. The AO indices distribution also shifted towards positive values. East Asian BC had similar impacts to that of global BC, while the responses to European BC were of opposite sign. South Asian BC and North American BC did not affect the AO significantly. Based on a simple linear assumption, we roughly estimated that the global BC emission increase could explain approximately 5% of the observed positive AO trend of +0.32 per decade during 1960 to 2000.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jointly supported by the National Basic Research Program of China(973 Program,2015CB453202 and 2012CB417403)the National Natural Science Foundation of China(41421004)
文摘The responses of the Arctic Oscillation(AO) to global black carbon(BC) and BC emitted from major regions were compared using the atmospheric general circulation model Geophysical Fluid Dynamics Laboratory(GFDL) atmospheric general circulation model(AGCM) Atmospheric Model version 2.1(AM2.1). The results indicated that global BC could induce positive-phase AO responses, characterized by negative responses over the polar cap on 500 h Pa height fields, and zonal mean sea level pressure(SLP) decreasing while zonal wind increasing at 60°, with the opposite responses over midlatitudes. The AO indices distribution also shifted towards positive values. East Asian BC had similar impacts to that of global BC, while the responses to European BC were of opposite sign. South Asian BC and North American BC did not affect the AO significantly. Based on a simple linear assumption, we roughly estimated that the global BC emission increase could explain approximately 5% of the observed positive AO trend of +0.32 per decade during 1960 to 2000.
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.
