scholarly journals A GCM study of effects of radiative forcing of sulfate aerosol on large scale circulation and rainfall in East Asia during boreal spring

2007 ◽  
Vol 34 (24) ◽  
Author(s):  
Maeng-Ki Kim ◽  
William K. M. Lau ◽  
Kyu-Myong Kim ◽  
Woo-Seop Lee
Keyword(s):  
East Asia ◽  
Radiative Forcing ◽  
Large Scale ◽  
Sulfate Aerosol ◽  
Large Scale Circulation ◽  
Boreal Spring

Large-Scale Circulation Anomalies Associated with Extreme Heat in South Korea and Southern–Central Japan

2020 ◽  
Author(s):  
Ke Xu
Keyword(s):  
South Korea ◽  
East Asia ◽  
Large Scale ◽  
Extreme Heat ◽  
Central Japan ◽  
Large Scale Circulation ◽  
Westerly Jet ◽  
Anomalous Anticyclone ◽  
Wave Trains ◽  
Circulation Anomalies

<p>    The large-scale circulation anomalies associated with extreme heat (EH) in South Korea and southern–central Japan are examined using data during the time period 1979–2016. Statistical analysis indicates that EH days in these two regions are concentrated in July and August and tend to occur simultaneously. These EH days are therefore combined to explore the physical mechanisms leading to their occurrence. The composite results indicate that the anomalous atmospheric warming during EH days is dominantly caused by a significant subsidence anomaly, which is associated with a deep anomalous anticyclone over East Asia. Further investigation of the evolution of circulation anomalies suggests that the anomalous anticyclone over East Asia related to EH is primarily initiated by wave trains originating from upstream regions, which propagate eastward along the Asian westerly jet in the upper troposphere. These wave trains can be categorized into two types that are characterized by the precursor anticyclonic and cyclonic anomalies, respectively, over central Asia. The distinction between these two types of wave train can be explained by the wavenumbers of the Rossby waves, which are modulated by both the intensity and the shape of the Asian westerly jet as the background basic flow.</p>

scholarly journals Differences in Sulfate Aerosol Radiative Forcing between the Daytime and Nighttime over East Asia Using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) Model

Atmosphere ◽  
2018 ◽  
Vol 9 (11) ◽  
pp. 441 ◽  
Author(s):  
Hongyue Zhang ◽  
Siyu Chen ◽  
Nanxuan Jiang ◽  
Xin Wang ◽  
Xiaorui Zhang ◽  
...  
Keyword(s):  
Climate Change ◽  
East Asia ◽  
Radiative Forcing ◽  
Eastern China ◽  
Sulfate Aerosol ◽  
Weather Research And Forecasting ◽  
Forecasting Model ◽  
Sulfate Aerosols ◽  
Aerosol Radiative Forcing ◽  
Aerosol Radiative

The effect of aerosols is an important indicator of climate change. Sulfate aerosols, as the major scattering aerosols, which have attracted more and more attention in recent years. The Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) were utilized to investigate the spatial distribution of sulfate aerosols and their radiative forcing characteristics over East Asia in 2010. Results showed that sulfate aerosols were mainly distributed over eastern China (24–43° N, 101–126° E), especially in the Sichuan Basin. The concentration of sulfate aerosols decreased with increasing altitude over East Asia. It also exhibited obvious seasonal variations, where the largest range of sulfate aerosol concentrations was found in summer, with a maximum of 2.4 μg kg−1 over eastern China. Although sulfate aerosol concentrations varied slightly during day and night, there was still a significantly difference in the sulfate aerosol radiative forcing. Specifically, the magnitude of the direct radiative forcing induced by sulfate aerosols at the surface was approximately −3.02 W m−2 in the daytime, while that was +0.24 W m−2 in the nighttime. This asymmetric change that was caused by the radiative forcing of sulfate aerosols between day and night would have significant impacts on climate change at the regional scale.

scholarly journals Isotopic constraints on the role of hypohalous acids in sulfate aerosol formation in the remote marine boundary layer

2016 ◽  
Author(s):  
Qianjie Chen ◽  
Lei Geng ◽  
Johan A. Schmidt ◽  
Zhouqing Xie ◽  
Hui Kang ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Radiative Forcing ◽  
Large Scale ◽  
Climate Models ◽  
Marine Boundary Layer ◽  
Reaction Rates ◽  
Sulfate Aerosol ◽  
Aerosol Formation ◽  
Sulfate Production ◽  
Hypohalous Acids

Abstract. Sulfate is an important component of global atmospheric aerosol, and has partially compensated for greenhouse gas-induced warming during the industrial period. The magnitude of direct and indirect radiative forcing of aerosols since preindustrial time is a large uncertainty in climate models, which has been attributed largely to uncertainties in the preindustrial environment. Here, we report observations of the oxygen isotopic composition (Δ17O) of sulfate aerosol collected in the remote marine boundary layer (MBL) in spring and summer in order to evaluate sulfate production mechanisms in pristine-like environments. Model-aided analysis of the observations suggests that 33–50 % of sulfate in the MBL is formed via oxidation by hypohalous acids (HOX = HOBr + HOCl), a production mechanism typically excluded in large scale models due to uncertainties in the reaction rates. Based on the estimated fraction of sulfate formed via HOX oxidation, we further estimate that daily-averaged HOX concentrations on the order of 0.01–0.1 parts per trillion (ppt = pmol / mol) in the remote MBL during spring and summer are sufficient to explain the observations.

scholarly journals A Model Intercomparison of Stratospheric Solar Geoengineering by Accumulation-Mode Sulfate Aerosols

2021 ◽  
Author(s):  
Debra K. Weisenstein ◽  
Daniele Visioni ◽  
Henning Franke ◽  
Ulrike Niemeier ◽  
Sandro Vattioni ◽  
...  
Keyword(s):  
Size Distribution ◽  
Radiative Forcing ◽  
Large Scale ◽  
Climate Model ◽  
Sulfate Aerosol ◽  
Aerosol Size Distribution ◽  
Dynamical Response ◽  
Model Intercomparison ◽  
Accumulation Mode ◽  
Solar Geoengineering

Abstract. Analyses of stratospheric solar geoengineering have focused on sulfate aerosol, and almost all climate model experiments on sulfate aerosol have assumed injection of SO2. Yet continuous injection of SO2 may produce overly large aerosols. Injection of SO3 or H2SO4 from an aircraft in stratospheric flight is expected to produce new accumulation-mode particles (AM-H2SO4), and such injection may allow the sulfate aerosol size distribution to be nudged towards higher radiative efficacy. We report the first multi-model intercomparison of AM-H2SO4 injection. We compare three models: CESM2(WACCM), MAECHAM5-HAM, and SOCOL-AER coordinated as a testbed experiment within the Geoengineering Model Intercomparison Project (GeoMIP). The intercomparison explores how the injection of new accumulation-mode particles changes the large-scale particle size distribution and thus the overall radiative and dynamical response to sulfate aerosol injection. Each model used the same injection scenarios testing AM-H2SO4 and SO2 injections at 5 and 25 Tg(S) yr−1 to test linearity and climate response sensitivity. All three models find that AM-H2SO4 injection increases the radiative efficacy, defined as the radiative forcing per unit of sulfur injection, relative to SO2 injection. Increased radiative efficacy means that when compared to the use of SO2 to produce the same radiative forcing, AM-H2SO4 emissions could reduce some side-effects of sulfate aerosol geoengineering such as stratospheric heating. We explore the sensitivity to injection pattern by comparing injection at two points at 30° N and 30° S to injection in a belt along the equator between 30° S and 30° N, and find opposite impacts on radiative efficacy for AM-H2SO4 and SO2, suggesting that prior model results for concentrated injection of SO2 may be strongly dependent on model resolution. Model differences arise from differences in aerosol formulation and differences in model transport and resolution, factors whose interplay cannot be easily untangled by this intercomparison.

scholarly journals Isotopic constraints on the role of hypohalous acids in sulfate aerosol formation in the remote marine boundary layer

2016 ◽  
Vol 16 (17) ◽  
pp. 11433-11450 ◽  
Author(s):  
Qianjie Chen ◽  
Lei Geng ◽  
Johan A. Schmidt ◽  
Zhouqing Xie ◽  
Hui Kang ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Radiative Forcing ◽  
Large Scale ◽  
Climate Models ◽  
Marine Boundary Layer ◽  
Reaction Rates ◽  
Sulfate Aerosol ◽  
Aerosol Formation ◽  
Sulfate Production ◽  
Hypohalous Acids

Abstract. Sulfate is an important component of global atmospheric aerosol, and has partially compensated for greenhouse gas-induced warming during the industrial period. The magnitude of direct and indirect radiative forcing of aerosols since preindustrial times is a large uncertainty in climate models, which has been attributed largely to uncertainties in the preindustrial environment. Here, we report observations of the oxygen isotopic composition (Δ17O) of sulfate aerosol collected in the remote marine boundary layer (MBL) in spring and summer in order to evaluate sulfate production mechanisms in pristine-like environments. Model-aided analysis of the observations suggests that 33–50 % of sulfate in the MBL is formed via oxidation by hypohalous acids (HOX  =  HOBr + HOCl), a production mechanism typically excluded in large-scale models due to uncertainties in the reaction rates, which are due mainly to uncertainties in reactive halogen concentrations. Based on the estimated fraction of sulfate formed via HOX oxidation, we further estimate that daily-averaged HOX mixing ratios on the order of 0.01–0.1 parts per trillion (ppt  =  pmol/mol) in the remote MBL during spring and summer are sufficient to explain the observations.

scholarly journals Implications of a Decadal Climate Shift over East Asia in Winter: A Modeling Study

2010 ◽  
Vol 23 (18) ◽  
pp. 4989-5001 ◽  
Author(s):  
Song-You Hong ◽  
Yoo-Bin Yhang
Keyword(s):  
Climate Change ◽  
East Asia ◽  
Large Scale ◽  
Hydrological Cycle ◽  
East Asian ◽  
Lower Troposphere ◽  
Large Scale Circulation ◽  
Winter Climate ◽  
Climate Shift ◽  
Decadal Climate

Abstract This study investigates a decadal climate shift over East Asia in winter, focusing on the changes in hydrological cycle as well as large-scale circulation using the National Centers for Environmental Prediction (NCEP) Regional Spectral Model (RSM). The RSM is forced by perfect boundary conditions for winter (December–February) from 1979 to 2007. Analyses for two separate periods (1979–87 and 1999–2007) are performed to investigate the regional climate model’s ability to simulate climate change in precipitation as well as large-scale circulation. The RSM reproduces differences in large-scale features associated with winter climate change over East Asia when the winter monsoon is modulated on decadal time scales with its weakening pattern observed since the late 1980s. The model adequately reproduces a weakening of the Siberian high and shallowness of the Aleutian low in the lower troposphere and a weakened East Asian coastal trough and East Asian jet in the upper troposphere during 1999–2007, as compared to the first nine winters of 1979–87. Conversely, the decadal shift in precipitation is not well reproduced by the model. The model is capable of reproducing the power spectrum of daily precipitation with maxima at 8.5 days and 45 days in 1979–87, whereas widely spread peaks in 1999–2007 are not captured. The increase of precipitation due to parameterized convection is prominent. This study shows that the dynamical numerical model has a limited capability to reproduce the wintertime hydrological climate over East Asia associated with global warming in recent years.

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