The direct climatic effect of aerosols for the 1980-2000 period over East Asia was numerically investigated by a regional scale coupled climate-chemistry/aerosol model,which includes major anthropogenic aerosols(sulfa...The direct climatic effect of aerosols for the 1980-2000 period over East Asia was numerically investigated by a regional scale coupled climate-chemistry/aerosol model,which includes major anthropogenic aerosols(sulfate,black carbon,and organic carbon) and natural aerosols(soil dust and sea salt) .Anthropogenic emissions used in model simulation are from a global emission inventory prepared for the Intergovernmental Panel on Climate Change Fifth Assessment Report(IPCC AR5) ,whereas natural aerosols are calculated online in the model.The simulated 20-year average direct solar radiative effect due to aerosols at the surface was estimated to be in a range of-9--33 W m-2 over most areas of China,with maxima over the Gobi desert of West China,and-12 W m-2 to-24 W m-2 over the Sichuan Basin,the middle and lower reaches of the Yellow River and the Yangtze River.Aerosols caused surface cooling in most areas of East Asia,with maxima of-0.8-C to-1.6-C over the deserts of West China,the Sichuan Basin,portions of central China,and the middle reaches of the Yangtze River. Aerosols induced a precipitation decrease over almost the entire East China,with maxima of-90 mm/year to-150 mm/year over the Sichuan Basin,the middle reaches of the Yangtze River and the lower reaches of the Yellow River.Interdecadal variation of the climate response to the aerosol direct radiative effect is evident,indicating larger decrease in surface air temperature and stronger perturbation to precipitation in the 1990s than that in the 1980s,which could be due to the interdecadal variation of anthropogenic emissions.展开更多
In this study, a regional air quality model system (RAQMS) was applied to investigate the spatial distributions and seasonal variations of atmospheric aerosols in 2006 over East Asia. Model validations demonstrated ...In this study, a regional air quality model system (RAQMS) was applied to investigate the spatial distributions and seasonal variations of atmospheric aerosols in 2006 over East Asia. Model validations demonstrated that RAQMS was able to reproduce the evolution processes of aerosol components reasonably well. Ground-level PM10 (particles with aerodynamic diameter ≤10 μm) concentrations were highest in spring and lowest in summer and were characterized by three maximum centers: the Taklimakan Desert (-1000 μg m^-3), the Gobi Desert (-400 μg m^-3), and the Huabei Plain (- 300 μg m^-3) of China. Vertically, high PM10 concentrations ranging from 100 μg m-3 to 250 μg m-3 occurred from the surface to an altitude of 6000 m at 30°-45°N in spring. In winter, the vertical gradient was so large that most aerosols were restricted in the boundary layer. Both sulfate and ammonium reached their highest concentrations in autumn, while nitrate reached its maximum level in winter. Black carbon and organic carbon aerosol concentrations reached maximums in winter. Soil dust were strongest in spring, whereas sea salt exerted the strongest influence on the coastal regions of eastern China in summer. The estimated burden of anthropogenic aerosols was largest in winter (1621 Gg) and smallest in summer (1040 Gg). The sulfate burden accounted for -42% of the total anthropogenic aerosol burden. The dust burden was about twice the anthropogenic aerosol burden, implying the potentially important impacts of the natural aerosols on air quality and climate over East Asia.展开更多
Taking winter and summer in eastern China as an example application, a grid-cell method of aerosol direct radiative forcing(ADRF) calculation is examined using the Santa Barbara DISORT Atmospheric Radiative Transfer...Taking winter and summer in eastern China as an example application, a grid-cell method of aerosol direct radiative forcing(ADRF) calculation is examined using the Santa Barbara DISORT Atmospheric Radiative Transfer(SBDART) model with inputs from MODIS and AERONET observations and reanalysis data. Results show that there are significant seasonal and regional differences in climatological mean aerosol optical parameters and ADRF. Higher aerosol optical depth(AOD)occurs in summer and two prominent high aerosol loading centers are observed. Higher single scattering albedo(SSA) in summer is likely associated with the weak absorbing secondary aerosols. SSA is higher in North China during summer but higher in South China during winter. Aerosols induce negative forcing at the top of the atmosphere(TOA) and surface during both winter and summer, which may be responsible for the decrease in temperature and the increase in relative humidity.Values of ADRF at the surface are four times stronger than those at the TOA. Both AOD and ADRF present strong interannual variations; however, their amplitudes are larger in summer. Moreover, patterns and trends of ADRF do not always correspond well to those of AOD. Differences in the spatial distributions of ADRF between strong and weak monsoon years are captured effectively. Generally, the present results justify that to calculate grid-cell ADRF at a large scale using the SBDART model with observational aerosol optical properties and reanalysis data is an effective approach.展开更多
Aerosol optical properties are simulated using the Spectral Radiation Transport Model I~)r Aerosol Species (SPRINTARS) coupled with the Non-hydrostatic ICosahedral Atmospheric Model (NICAM). The 3-year global mea...Aerosol optical properties are simulated using the Spectral Radiation Transport Model I~)r Aerosol Species (SPRINTARS) coupled with the Non-hydrostatic ICosahedral Atmospheric Model (NICAM). The 3-year global mean all-sky aerosol optical thickness (AOT) at 550 nm, theAngstr/Sm Exponent (AE) based on AOTs at 440 and 870 nm, and the single scattering albedo (SSA) at 550 nm are estimated at 0.123, 0.657 and 0.944, respectively. For each aerosol species, the mean AOT is within the range of the AeroCom models. Both the modeled all-sky and clear-sky results are compared with observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Aerosol Robotic Network (AERONET). The simulated spatiotemporal distributions of all-sky AOTs can generally reproduce the MODIS retrievals, and the correlation and model skill can be slightly improved using the clear-sky results over most land regions. The differences between clear-sky and all-sky AOTs are larger over polluted regions. Compared with observations from AERONET, the modeled and observed all-sky AOTs and AEs are generally in reasonable agreement, whereas the SSA variation is not well captured. Although the spatiotemporal distributions of all-sky and clear-sky results are similar, the clear-sky results are generally better correlated with the observations. The clear-sky AOT and SSA are generally lower than the all-sky results, especially in those regions where the aerosol chemical composition is contributed to mostly by sulfate aerosol. The modeled clear-sky AE is larger than the all-sky AE over those regions dominated by hydrophilic aerosol, while the'opposite is found over regions dominated by hydrophobic aerosol.展开更多
The authors present spatial and temporal characteristics of anthropogenic sulfate and carbonaceous aerosols over East Asia using a 3-D coupled regional climate-chemistry-aerosol model, and compare the simulation with ...The authors present spatial and temporal characteristics of anthropogenic sulfate and carbonaceous aerosols over East Asia using a 3-D coupled regional climate-chemistry-aerosol model, and compare the simulation with the limited aerosol observations over the region. The aerosol module consists of SO2, SO4^2-, hydrophobic and hydrophilic black carbon (BC) and organic carbon compounds (OC), including emission, advections, dry and wet deposition, and chemical production and conversion. The simulated patterns of SO2 are closely tied to its emission rate, with sharp gradients between the highly polluted regions and more rural areas. Chemical conversion (especially in the aqueous phase) and dry deposition remove 60% and 30% of the total SO2 emission, respectively. The SO4^2- shows less horizontal gradient and seasonality than SO2, with wet deposition (60%) and export (27%) being two major sinks. Carbonaceous aerosols are spatially smoother than sulfur species. The aging process transforms more than 80% of hydrophobic BC and OC to hydrophilic components, which are removed by wet deposition (60%) and export (30%). The simulated spatial and seasonal SO4^2-, BC and OC aerosol concentrations and total aerosol optical depth are generally consistent with the observations in rural areas over East Asia, with lower bias in simulated OC aerosols, likely due to the underestimation of anthropogenic OC emissions and missing treatment of secondary organic carbon. The results suggest that our model is a useful tool for characterizing the anthropogenic aerosol cycle and for assessing its potential climatic and environmental effects in future studies.展开更多
Aerosol indirect effects on warm clouds are estimated in the Grid-point Atmospheric Model of the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics,Institute of Atmosphe...Aerosol indirect effects on warm clouds are estimated in the Grid-point Atmospheric Model of the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics,Institute of Atmospheric Physics(IAP LASG)(GAMIL) with a new two-moment cloud microphysics scheme using two different physically-based aerosol activation parameterizations:Abdul-Razzak and Ghan,and Nenes and Seinfeld.The annual global mean changes in shortwave cloud forcing from preindustrial times to present day(a measure of the aerosol indirect effects) estimated from these two parameterizations are remarkably similar:0.76 W m?2 with the Abdul-Razzak and Ghan parameterization,and 0.78 W m?2 with the Nenes and Seinfeld parameterization.Physically-based parameterizations can provide robust representations of aerosol effects on droplet nucleation,meaning that aerosol activation is no longer the most uncertain factor in modeling aerosol indirect effects.展开更多
This paper describes the latest progress of a collaborative research program entitled "Modeling Aerosol Climate Effects over Monsoon Asia", under the Climate Sciences agreement between the U.S. Department of Energy ...This paper describes the latest progress of a collaborative research program entitled "Modeling Aerosol Climate Effects over Monsoon Asia", under the Climate Sciences agreement between the U.S. Department of Energy and the Chinese Academy of Sciences(in the early 1980 s, Professor Duzheng YE played a critical role in leading and formalizing the agreement). Here, the rationale and approach for pursuing the program, the participants, and research activities of recent years are first described, and then the highlights of the program's key findings and relevant scientific issues, as well as follow-up studies, are presented and discussed.展开更多
Direct climate responses to dust shortwave and longwave radiative forcing (RF) are studied using the NCAR Community Atmosphere Model Version 3 (CAM3). The simulated RF at the top of the atmosphere (TOA) is-0.45 ...Direct climate responses to dust shortwave and longwave radiative forcing (RF) are studied using the NCAR Community Atmosphere Model Version 3 (CAM3). The simulated RF at the top of the atmosphere (TOA) is-0.45 W m-2 in the solar spectrum and +0.09 W m-2 in the thermal spectrum on a global average. The magnitude of surface RF is larger than the TOA forcing, with global mean shortwave forcing of-1.76 W m-2 and longwave forcing of +0.31 W m-2 . As a result, dust aerosol causes the absorption of 1.1 W m-2 in the atmosphere. The RF of dust aerosol is predicted to lead to a surface cooling of 0.5 K over the Sahara Desert and Arabian Peninsula. In the meantime, the upper troposphere is predicted to become warmer because of the absorption by dust. These changes in temperature lead to a more stable atmosphere, which results in increases in surface humidity. The upward sensible and latent heat fluxes at the surface are reduced, largely balancing the surface energy loss caused by the backscattering and absorption of dust aerosol. Precipitation is predicted to decrease moderately on a global scale.展开更多
This paper presents an empirical model for estimating the zonal mean aerosol extinction profiles in the stratosphere over 10°-wide latitude bands between 60°S and 60°N, on the basis of Stratospheric Aer...This paper presents an empirical model for estimating the zonal mean aerosol extinction profiles in the stratosphere over 10°-wide latitude bands between 60°S and 60°N, on the basis of Stratospheric Aerosol and Gas Experiment(SAGE) II aerosol extinction measurements at 1.02, 0.525, and 0.452 μm during the volcanically quiescent period between 1998–2004. First, an empirical model is developed for calculating the stratospheric aerosol extinction profiles at 1.02 μm. Then, starting from the 1.02 μm extinction profile and an exponential spectral dependence, an empirical algorithm is developed that allows the aerosol extinction profiles at other wavelengths to be calculated. Comparisons of the model-calculated aerosol extinction profiles at the wavelengths of 1.02, 0.525, and 0.452 μm and the SAGE II measurements show that the model-calculated aerosol extinction coefficients conform well with the SAGE II values, with the relative differences generally being within 15% from 2 km above the tropopause to 40 km. The model-calculated stratospheric aerosol optical depths at the three wavelengths are also in good agreement with the corresponding optical depths derived from the SAGE II measurements, with the relative differences being within 0.9% for all latitude bands. This paper provides a useful tool in simulating zonal mean aerosol extinction profiles, which can be used as representative background stratospheric aerosols in view of atmospheric modeling and remote sensing retrievals.展开更多
This study investigated the second indirect climatic effect of anthropogenic aerosols,including sulfate,organic carbon(OC) ,and black carbon(BC) ,over East Asia.The seasonal variation of the climatic response to the s...This study investigated the second indirect climatic effect of anthropogenic aerosols,including sulfate,organic carbon(OC) ,and black carbon(BC) ,over East Asia.The seasonal variation of the climatic response to the second indirect effect was also characterized.The simulation period for this study was 2006.Due to a decrease in autoconversion rate from cloud water to rain as a result of aerosols,the cloud liquid water path(LWP) ,and radiative flux(RF) at the top of the atmosphere(TOA) changed dramatically,increasing by 14.3 g m-2 and decreasing by-4.1 W m-2 in terms of domain and annual average.Both LWP and RF changed most in autumn. There were strong decreases in ground temperature in Southwest China,the middle reaches of the Yangtze River in spring and autumn,while maximum cooling of up to-1.5 K occurred in the Chongqing district.The regional and annual mean change in ground temperature reached-0.2 K over eastern China.In all seasons except summer,precipitation generally decreased in most areas north of the Yangtze River,whereas precipitation changed little in South China.Precipitation changed most in summer,with alternating bands of increasing(~40 mm) and decreasing(~40 mm) precipitation appearing in eastern China.Precipitation decreased by 1.5-40 mm over large areas of Northeast China and the Huabei Plain.The domain and annual mean change in precipitation was approximately-0.3 mm over eastern China.The maximum reduction in precipitation occurred in summer,with mean absolute and relative changes of-1.2 mm and-3.8%over eastern China.This study revealed considerable climate responses to the second indirect effect of aerosols over specific regions of China.展开更多
This work focuses on modeling the impact of desert aerosols on a mini central solar photovoltaic (PV). Our studied physical model is comparable to a multilayer. We have described and discretized the mathematical equat...This work focuses on modeling the impact of desert aerosols on a mini central solar photovoltaic (PV). Our studied physical model is comparable to a multilayer. We have described and discretized the mathematical equations which govern the physical model. Also, we analyzed the influence of the parameters τa and X on the solar radiation received at the surface of solar PV modules. The results of the study taken <span style="white-space:nowrap;"><span style="font-family:;" "=""><span style="font-family:Verdana;">from</span><b> <span style="color:#943634;"><a href="file:///C:/Users/test8/Desktop/7%E6%9C%88%20EPE13.7%20%E6%8F%92%E9%A1%B5%E7%A0%81%20%E4%BB%98%E5%96%9C%E4%BB%81%20%EF%BC%881%EF%BC%89/1-6202510.docx#f6"><span style="color:#943634;font-family:Verdana;">Figure</span><span style="color:#943634;font-family:Verdana;">s</span><span style="color:#943634;font-family:Verdana;"> 6</span><span style="color:#943634;font-family:Verdana;">(</span><span style="color:#943634;font-family:Verdana;">a</span><span style="color:#943634;font-family:Verdana;">)-(</span><span style="color:#943634;font-family:Verdana;">d</span><span style="color:#943634;font-family:Verdana;">)</span></a></span></b></span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">representing</span></span><span style="font-family:Verdana;"> the variations of the global solar radiation on the solstices and equinoxes as well as the 21 of the months of the year days understood show that: if τ</span><sub><span style="font-family:Verdana;">a </span></sub><span style="font-family:Verdana;">= 0 and </span><i><span style="font-family:Verdana;">X </span></i><span style="font-family:Verdana;">= 0, I</span><sub><span style="font-family:Verdana;">C </span></sub><span style="font-family:Verdana;">= 67.87%;if τ</span><sub><span style="font-family:Verdana;">a </span></sub><span style="font-family:Verdana;">= 0.5 and </span><i><span style="font-family:Verdana;">X </span></i><span style="font-family:Verdana;">= 0.5, I</span><sub><span style="font-family:Verdana;">C </span></sub><span style="font-family:Verdana;">= 21%;if τ</span><sub><span style="font-family:Verdana;">a </span></sub><span style="font-family:Verdana;">= 0.8 and </span><i><span style="font-family:Verdana;">X </span></i><span style="font-family:Verdana;">= 0.8, I</span><sub><span style="font-family:Verdana;">C </span></sub><span style="font-family:Verdana;">= 12% and if τ</span><sub><span style="font-family:Verdana;">a </span></sub><span style="font-family:Verdana;">= 1.5 and </span><i><span style="font-family:Verdana;">X </span></i><span style="font-family:Verdana;">= 1.5 then I</span><sub><span style="font-family:Verdana;">C </span></sub><span style="font-family:Verdana;">= 4%. These results show that desert aerosols significantly influence the global solar radiation received. Unfortunately, this influence lowers the productivity of the central solar PV in general.</span>展开更多
To realistically simulate the impacts of marine isoprene and primary organic aerosols (POA) on atmospheric chemistry, a unified model framework with online emissions, comprehensive treatment of gas-phase chemistry, an...To realistically simulate the impacts of marine isoprene and primary organic aerosols (POA) on atmospheric chemistry, a unified model framework with online emissions, comprehensive treatment of gas-phase chemistry, and advanced aerosol microphysics is required. In this work, the global-through-urban WRF/Chem model (GU-WRF/Chem) implemented with the online emissions of marine isoprene and size-resolved marine POA is applied to examine such impacts. The net effect of these emissions was increased surface concentrations of isoprene and organic aerosols and decreased surfaced concentrations of hydroxyl radical and ozone over most marine regions. With the inclusion of these emissions, GU-WRF/Chem better predicted the surface concentrations of isoprene and organic aerosols and the aerosol number size distribution when compared to measurements in clean marine conditions.展开更多
Contaminated or infected patients present a risk of cross-contamination for emergency responders, attending medical personnel and medical facilities as they enter a treatment facility. The controlled conditions of an ...Contaminated or infected patients present a risk of cross-contamination for emergency responders, attending medical personnel and medical facilities as they enter a treatment facility. The controlled conditions of an aerosol test chamber are required to examine factors of contamination, decontamination, and cross-contamination. This study presents the design, construction, and a method for characterizing an aerosol test chamber for a full-sized manikin on a standard North Atlantic Treaty Organization litter. The methodology combined air velocity measurements, aerosol particle counts and size distributions, and computational fluid dynamics modeling to describe the chamber’s performance in three dimensions. This detailed characterization facilitates future experimental design by predicting chamber performance for a variety of patient-focused research.展开更多
With the gradual yet unequivocal phasing out of ozone depleting substances(ODSs), the environmental crisis caused by the discovery of an ozone hole over the Antarctic has lessened in severity and a promising recovery ...With the gradual yet unequivocal phasing out of ozone depleting substances(ODSs), the environmental crisis caused by the discovery of an ozone hole over the Antarctic has lessened in severity and a promising recovery of the ozone layer is predicted in this century. However, strong volcanic activity can also cause ozone depletion that might be severe enough to threaten the existence of life on Earth. In this study, a transport model and a coupled chemistry–climate model were used to simulate the impacts of super volcanoes on ozone depletion. The volcanic eruptions in the experiments were the 1991 Mount Pinatubo eruption and a 100 × Pinatubo size eruption. The results show that the percentage of global mean total column ozone depletion in the 2050 RCP8.5 100 × Pinatubo scenario is approximately 6% compared to two years before the eruption and 6.4% in tropics. An identical simulation, 100 × Pinatubo eruption only with natural source ODSs, produces an ozone depletion of 2.5% compared to two years before the eruption, and with 4.4% loss in the tropics. Based on the model results,the reduced ODSs and stratospheric cooling lighten the ozone depletion after super volcanic eruption.展开更多
The International Centre for Theoretical Physics(ICTP,Italy) Regional Climate Model version 3.0(RegCM3) is used to simulate spatio-temporal distribution characteristics and radiative forcing(RF) of organic carbon(OC) ...The International Centre for Theoretical Physics(ICTP,Italy) Regional Climate Model version 3.0(RegCM3) is used to simulate spatio-temporal distribution characteristics and radiative forcing(RF) of organic carbon(OC) aerosols in and around China.The preliminary simulation results show that OC aerosols are mostly concentrated in the area to the south of Yellow River and east of Tibetan Plateau.There is a decreasing trend of column burden of OC aerosols from south to north in China.The maximum value of column burden of OC aerosols is above 3 mg/m2 and located in the central and southern China,southeastern Tibet,and southwestern China's Yunnan,Guizhou,Sichuan provinces.The simulation on the seasonal variation shows that the maximum value of column burden of OC aerosols appears in winter and the secondary value is in spring and the minimum in summer.The RF of OC aerosols which varies seasonally is negative at the top of the atmosphere(TOA) and surface.The spatio-temporal characteristics of the RF of OC aerosols are basically consistent with that of IPCC,implying the high accuracy of the parameterization scheme for OC aerosols in RegCM3.展开更多
A one-dimensional 3rd-order turbulence closure model with size-resolved microphysics and radiative transfer has been developed for investigating aerosol and cloud interactions of the stratocumulus-topped marine bounda...A one-dimensional 3rd-order turbulence closure model with size-resolved microphysics and radiative transfer has been developed for investigating aerosol and cloud interactions of the stratocumulus-topped marine boundary layer. A new method is presented for coupling between the dynamical model and the microphysical model. This scheme allows the liquid water related correlations to be directly calculated rather than parameterized. On 21 April 2001, a marine stratocumulus was observed by the Caesar aircraft over the west Pacific Rim south of Japan during the 2001 APEX/ACE-Asia field measurements. This cloud is simulated by the model we present here. The model results show that the general features of the stratocumulus-topped marine boundary layer predicted by the model are in agreement with the measurements. A new onboard cloud condensation nuclei (CCN) counter provides not only total CCN number concentration (as the traditional CCN counters do at a certain supersaturation) but also the CCN size distribution information. Using these CCN data, model responses to different CCN initial concentrations are examined. The model results are consistent with both observations and expectations. The numerical results show that the cloud microphysical properties are changed fundamentally by different initial CCN concentrations but the cloud liquid water content does not differ significantly. Different initial CCN loadings have large impacts on the evolution of cloud microstructure and radiation transfer while they have a modest effect on thermodynamics. Increased CCN concentration leads to significant decrease of cloud effective radius.展开更多
The authors used a high-resolution regional climate model(RegCM3) coupled with a chemistry/aerosol module to simulate East Asian climate in 2006 and to test the climatic impacts of aerosols on regionalscale climate.Th...The authors used a high-resolution regional climate model(RegCM3) coupled with a chemistry/aerosol module to simulate East Asian climate in 2006 and to test the climatic impacts of aerosols on regionalscale climate.The direct radiative forcing and climatic effects of aerosols(dust,sulfate,black carbon,and organic carbon) were discussed.The results indicated that aerosols generally produced negative radiative forcing at the top-of-the-atmosphere(TOA) over most areas of East Asia.The radiative forcing induced by aerosols exhibited significant seasonal and regional variations,with the strongest forcing occurring in summer.The aerosol feedbacks on surface air temperature and precipitation were clear.Surface cooling dominated features over the East Asian continental areas,which varied in the approximate range of-0.5 to-2°C with the maximum up to-3-C in summer over the deserts of West China.The aerosols induced complicated variations of precipitation.Except in summer,the rainfall generally varied in the range of-1 to 1 mm d-1 over most areas of China.展开更多
The Weather Research and Forecasting/Chemistry model (WRF-Chem) was updated by including pho- toexeited nitrogen dioxide (NO2) molecules, heterogeneous reactions on aerosol surfaces, and direct emissions of nitrou...The Weather Research and Forecasting/Chemistry model (WRF-Chem) was updated by including pho- toexeited nitrogen dioxide (NO2) molecules, heterogeneous reactions on aerosol surfaces, and direct emissions of nitrous acid (HONO) in the Carbon-Bond Mechanism Z (CBM-Z). Five simulations were conducted to assess the effects of each new component and the three additional HONO sources on concentrations of major chemical components. We calculated percentage changes of major aerosol components and concentration ratios of gas NOy (NOyg) to NOy and particulate nitrates (NO3-) to NOy due to the three additional HONO sources in the North China Plain in August of 2007. Our results indicate that when the three additional HONO sources are included, WRF-Chem can reasonably reproduce the HONO observations. Heterogeneous reactions on aerosol surfaces are a key contributor to concentrations of HONO, nitrates (NO3-), ammonium (NH+), and PM2.5 (concentration of particulate matter of ≤2.5 um in the ambient air) across the North China Plain. The three additional HONO sources produced a -5% -20% increase in monthly mean daytime concentration ratios of NO3-/NOy, a -15%- 52% increase in maximum hourly mean concentration ratios of NO3-/NOy, and a -10% -50% increase in monthly mean concentrations of NOx and NH+ across large areas of the North China Plain. For the Bohai Bay, the largest hourly increases of NO3- exceeded 90%, of NH+ exceeded 80%, and of PM2.5 exceeded 40%, due to the three additional HONO sources. This implies that the three additional HONO sources can aggravate regional air pollution, further impair visibility, and enhance the incidence of haze in some industrialized regions with high emissions of NOx and particulate matter under favorable meteorological conditions.展开更多
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No.KZCX2-YW-Q11-03)the"Strategic Priority Research Program"of the Chinese Academy of Sciences(Grant No. XDA05100502)+1 种基金the National Basic Research Program of China (Grant No.2010CB950804)100 Talents Program of the Chinese Academy of Sciences
文摘The direct climatic effect of aerosols for the 1980-2000 period over East Asia was numerically investigated by a regional scale coupled climate-chemistry/aerosol model,which includes major anthropogenic aerosols(sulfate,black carbon,and organic carbon) and natural aerosols(soil dust and sea salt) .Anthropogenic emissions used in model simulation are from a global emission inventory prepared for the Intergovernmental Panel on Climate Change Fifth Assessment Report(IPCC AR5) ,whereas natural aerosols are calculated online in the model.The simulated 20-year average direct solar radiative effect due to aerosols at the surface was estimated to be in a range of-9--33 W m-2 over most areas of China,with maxima over the Gobi desert of West China,and-12 W m-2 to-24 W m-2 over the Sichuan Basin,the middle and lower reaches of the Yellow River and the Yangtze River.Aerosols caused surface cooling in most areas of East Asia,with maxima of-0.8-C to-1.6-C over the deserts of West China,the Sichuan Basin,portions of central China,and the middle reaches of the Yangtze River. Aerosols induced a precipitation decrease over almost the entire East China,with maxima of-90 mm/year to-150 mm/year over the Sichuan Basin,the middle reaches of the Yangtze River and the lower reaches of the Yellow River.Interdecadal variation of the climate response to the aerosol direct radiative effect is evident,indicating larger decrease in surface air temperature and stronger perturbation to precipitation in the 1990s than that in the 1980s,which could be due to the interdecadal variation of anthropogenic emissions.
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KZCX2-YW-Q11-03)the "Strategic Priority Research Program" of the Chinese Academy of Sciences (Grant No. XDA05100502)+2 种基金the National 973 Project of China (Grant No. 2010CB950804)the National Natural Science Foundation of China (GrantNo. 41075106)the Hundred Talents Program of the Chinese Academy of Sciences
文摘In this study, a regional air quality model system (RAQMS) was applied to investigate the spatial distributions and seasonal variations of atmospheric aerosols in 2006 over East Asia. Model validations demonstrated that RAQMS was able to reproduce the evolution processes of aerosol components reasonably well. Ground-level PM10 (particles with aerodynamic diameter ≤10 μm) concentrations were highest in spring and lowest in summer and were characterized by three maximum centers: the Taklimakan Desert (-1000 μg m^-3), the Gobi Desert (-400 μg m^-3), and the Huabei Plain (- 300 μg m^-3) of China. Vertically, high PM10 concentrations ranging from 100 μg m-3 to 250 μg m-3 occurred from the surface to an altitude of 6000 m at 30°-45°N in spring. In winter, the vertical gradient was so large that most aerosols were restricted in the boundary layer. Both sulfate and ammonium reached their highest concentrations in autumn, while nitrate reached its maximum level in winter. Black carbon and organic carbon aerosol concentrations reached maximums in winter. Soil dust were strongest in spring, whereas sea salt exerted the strongest influence on the coastal regions of eastern China in summer. The estimated burden of anthropogenic aerosols was largest in winter (1621 Gg) and smallest in summer (1040 Gg). The sulfate burden accounted for -42% of the total anthropogenic aerosol burden. The dust burden was about twice the anthropogenic aerosol burden, implying the potentially important impacts of the natural aerosols on air quality and climate over East Asia.
基金supported by the Chinese Academy of Sciences Strategic Priority Research Program(Grant No.XDA05100303)the National Natural Science Foundation of China(Grant Nos.41230419,91337213 and 41075041)the Special Funds for Public Welfare of China(Grant No.GYHY201306077)
文摘Taking winter and summer in eastern China as an example application, a grid-cell method of aerosol direct radiative forcing(ADRF) calculation is examined using the Santa Barbara DISORT Atmospheric Radiative Transfer(SBDART) model with inputs from MODIS and AERONET observations and reanalysis data. Results show that there are significant seasonal and regional differences in climatological mean aerosol optical parameters and ADRF. Higher aerosol optical depth(AOD)occurs in summer and two prominent high aerosol loading centers are observed. Higher single scattering albedo(SSA) in summer is likely associated with the weak absorbing secondary aerosols. SSA is higher in North China during summer but higher in South China during winter. Aerosols induce negative forcing at the top of the atmosphere(TOA) and surface during both winter and summer, which may be responsible for the decrease in temperature and the increase in relative humidity.Values of ADRF at the surface are four times stronger than those at the TOA. Both AOD and ADRF present strong interannual variations; however, their amplitudes are larger in summer. Moreover, patterns and trends of ADRF do not always correspond well to those of AOD. Differences in the spatial distributions of ADRF between strong and weak monsoon years are captured effectively. Generally, the present results justify that to calculate grid-cell ADRF at a large scale using the SBDART model with observational aerosol optical properties and reanalysis data is an effective approach.
基金National Natural Science Funds of China (Grant Nos. 41130104, and 41475031)Open Research Program of Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration from Nanjing University of Information Science and Technology (Grant No. KDW1302)+4 种基金the Public Meteorology Special Foundation of MOST (Grant No. GYHY201406023)the National Key Basic Research and Development Program (973 Program, 2011CB403401)Teruyuki NAKAJIMA is supported by projects from JAXA/EarthC ARE, MEXT/VL for Climate System Diagnosticsthe MOE/Global Environment Research Fund A-1101, NIES/GOSAT, NIES/CGER, MEXT/RECCA/SALSAthe S-12 of the MOE
文摘Aerosol optical properties are simulated using the Spectral Radiation Transport Model I~)r Aerosol Species (SPRINTARS) coupled with the Non-hydrostatic ICosahedral Atmospheric Model (NICAM). The 3-year global mean all-sky aerosol optical thickness (AOT) at 550 nm, theAngstr/Sm Exponent (AE) based on AOTs at 440 and 870 nm, and the single scattering albedo (SSA) at 550 nm are estimated at 0.123, 0.657 and 0.944, respectively. For each aerosol species, the mean AOT is within the range of the AeroCom models. Both the modeled all-sky and clear-sky results are compared with observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Aerosol Robotic Network (AERONET). The simulated spatiotemporal distributions of all-sky AOTs can generally reproduce the MODIS retrievals, and the correlation and model skill can be slightly improved using the clear-sky results over most land regions. The differences between clear-sky and all-sky AOTs are larger over polluted regions. Compared with observations from AERONET, the modeled and observed all-sky AOTs and AEs are generally in reasonable agreement, whereas the SSA variation is not well captured. Although the spatiotemporal distributions of all-sky and clear-sky results are similar, the clear-sky results are generally better correlated with the observations. The clear-sky AOT and SSA are generally lower than the all-sky results, especially in those regions where the aerosol chemical composition is contributed to mostly by sulfate aerosol. The modeled clear-sky AE is larger than the all-sky AE over those regions dominated by hydrophilic aerosol, while the'opposite is found over regions dominated by hydrophobic aerosol.
基金funds from the U. S. Na- tional Aeronautics and Space Administration under Grant NNG04GB89G the U. S. National Science Foundation under grant ATM-0129495
文摘The authors present spatial and temporal characteristics of anthropogenic sulfate and carbonaceous aerosols over East Asia using a 3-D coupled regional climate-chemistry-aerosol model, and compare the simulation with the limited aerosol observations over the region. The aerosol module consists of SO2, SO4^2-, hydrophobic and hydrophilic black carbon (BC) and organic carbon compounds (OC), including emission, advections, dry and wet deposition, and chemical production and conversion. The simulated patterns of SO2 are closely tied to its emission rate, with sharp gradients between the highly polluted regions and more rural areas. Chemical conversion (especially in the aqueous phase) and dry deposition remove 60% and 30% of the total SO2 emission, respectively. The SO4^2- shows less horizontal gradient and seasonality than SO2, with wet deposition (60%) and export (27%) being two major sinks. Carbonaceous aerosols are spatially smoother than sulfur species. The aging process transforms more than 80% of hydrophobic BC and OC to hydrophilic components, which are removed by wet deposition (60%) and export (30%). The simulated spatial and seasonal SO4^2-, BC and OC aerosol concentrations and total aerosol optical depth are generally consistent with the observations in rural areas over East Asia, with lower bias in simulated OC aerosols, likely due to the underestimation of anthropogenic OC emissions and missing treatment of secondary organic carbon. The results suggest that our model is a useful tool for characterizing the anthropogenic aerosol cycle and for assessing its potential climatic and environmental effects in future studies.
基金supported by the National High Technology Research and Development Program of China (Grant No. 2010AA012304)the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KZCX2-YW-Q11-04)the China Meteorological Administration for the R&D Special Fund for Public Welfare Industry (meteorology) (Grant Nos. GYHY200806006 and GYHY200906020)
文摘Aerosol indirect effects on warm clouds are estimated in the Grid-point Atmospheric Model of the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics,Institute of Atmospheric Physics(IAP LASG)(GAMIL) with a new two-moment cloud microphysics scheme using two different physically-based aerosol activation parameterizations:Abdul-Razzak and Ghan,and Nenes and Seinfeld.The annual global mean changes in shortwave cloud forcing from preindustrial times to present day(a measure of the aerosol indirect effects) estimated from these two parameterizations are remarkably similar:0.76 W m?2 with the Abdul-Razzak and Ghan parameterization,and 0.78 W m?2 with the Nenes and Seinfeld parameterization.Physically-based parameterizations can provide robust representations of aerosol effects on droplet nucleation,meaning that aerosol activation is no longer the most uncertain factor in modeling aerosol indirect effects.
基金support by a grant from the Office of Sciences(BER),U.S.DOEsupport from the Key National Basic Research Program on Global Change(Grant No.2013CB955803)to facilitate the visits to Peking University and the Institute of Atmospheric Physics
文摘This paper describes the latest progress of a collaborative research program entitled "Modeling Aerosol Climate Effects over Monsoon Asia", under the Climate Sciences agreement between the U.S. Department of Energy and the Chinese Academy of Sciences(in the early 1980 s, Professor Duzheng YE played a critical role in leading and formalizing the agreement). Here, the rationale and approach for pursuing the program, the participants, and research activities of recent years are first described, and then the highlights of the program's key findings and relevant scientific issues, as well as follow-up studies, are presented and discussed.
基金supported by the Key Project of Chinese Academy of Sciences under Grant KZCX2-YW-Q11-03supported by the National Basic Research Program of China ("973" program) under Grant2006CB403705+1 种基金the Key Project of Chinese Academy of Sciences under Grants KZCX2-YW-Q1-02, KZCX2-YW-205, and KZCX2-YW-219the National Natural Science Foundation of China under Grant No. 40631005
文摘Direct climate responses to dust shortwave and longwave radiative forcing (RF) are studied using the NCAR Community Atmosphere Model Version 3 (CAM3). The simulated RF at the top of the atmosphere (TOA) is-0.45 W m-2 in the solar spectrum and +0.09 W m-2 in the thermal spectrum on a global average. The magnitude of surface RF is larger than the TOA forcing, with global mean shortwave forcing of-1.76 W m-2 and longwave forcing of +0.31 W m-2 . As a result, dust aerosol causes the absorption of 1.1 W m-2 in the atmosphere. The RF of dust aerosol is predicted to lead to a surface cooling of 0.5 K over the Sahara Desert and Arabian Peninsula. In the meantime, the upper troposphere is predicted to become warmer because of the absorption by dust. These changes in temperature lead to a more stable atmosphere, which results in increases in surface humidity. The upward sensible and latent heat fluxes at the surface are reduced, largely balancing the surface energy loss caused by the backscattering and absorption of dust aerosol. Precipitation is predicted to decrease moderately on a global scale.
基金supported by the National Natural Science Foundation of China (Grant No. 41275047)the National Basic Research Program of China (Grant No. 2013CB955801)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA05100300)
文摘This paper presents an empirical model for estimating the zonal mean aerosol extinction profiles in the stratosphere over 10°-wide latitude bands between 60°S and 60°N, on the basis of Stratospheric Aerosol and Gas Experiment(SAGE) II aerosol extinction measurements at 1.02, 0.525, and 0.452 μm during the volcanically quiescent period between 1998–2004. First, an empirical model is developed for calculating the stratospheric aerosol extinction profiles at 1.02 μm. Then, starting from the 1.02 μm extinction profile and an exponential spectral dependence, an empirical algorithm is developed that allows the aerosol extinction profiles at other wavelengths to be calculated. Comparisons of the model-calculated aerosol extinction profiles at the wavelengths of 1.02, 0.525, and 0.452 μm and the SAGE II measurements show that the model-calculated aerosol extinction coefficients conform well with the SAGE II values, with the relative differences generally being within 15% from 2 km above the tropopause to 40 km. The model-calculated stratospheric aerosol optical depths at the three wavelengths are also in good agreement with the corresponding optical depths derived from the SAGE II measurements, with the relative differences being within 0.9% for all latitude bands. This paper provides a useful tool in simulating zonal mean aerosol extinction profiles, which can be used as representative background stratospheric aerosols in view of atmospheric modeling and remote sensing retrievals.
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant No. KZCX2-YW-Q11-03)the"Strategic Priority Research Program"of the Chinese Academy of Sciences(Grant No.XDA05100502)+1 种基金the R&D Special Fund for Public Welfare Industry(Meteorology) (Grant No.GYHY200906020)100 Talents Program of the Chinese Academy of Sciences
文摘This study investigated the second indirect climatic effect of anthropogenic aerosols,including sulfate,organic carbon(OC) ,and black carbon(BC) ,over East Asia.The seasonal variation of the climatic response to the second indirect effect was also characterized.The simulation period for this study was 2006.Due to a decrease in autoconversion rate from cloud water to rain as a result of aerosols,the cloud liquid water path(LWP) ,and radiative flux(RF) at the top of the atmosphere(TOA) changed dramatically,increasing by 14.3 g m-2 and decreasing by-4.1 W m-2 in terms of domain and annual average.Both LWP and RF changed most in autumn. There were strong decreases in ground temperature in Southwest China,the middle reaches of the Yangtze River in spring and autumn,while maximum cooling of up to-1.5 K occurred in the Chongqing district.The regional and annual mean change in ground temperature reached-0.2 K over eastern China.In all seasons except summer,precipitation generally decreased in most areas north of the Yangtze River,whereas precipitation changed little in South China.Precipitation changed most in summer,with alternating bands of increasing(~40 mm) and decreasing(~40 mm) precipitation appearing in eastern China.Precipitation decreased by 1.5-40 mm over large areas of Northeast China and the Huabei Plain.The domain and annual mean change in precipitation was approximately-0.3 mm over eastern China.The maximum reduction in precipitation occurred in summer,with mean absolute and relative changes of-1.2 mm and-3.8%over eastern China.This study revealed considerable climate responses to the second indirect effect of aerosols over specific regions of China.
文摘This work focuses on modeling the impact of desert aerosols on a mini central solar photovoltaic (PV). Our studied physical model is comparable to a multilayer. We have described and discretized the mathematical equations which govern the physical model. Also, we analyzed the influence of the parameters τa and X on the solar radiation received at the surface of solar PV modules. The results of the study taken <span style="white-space:nowrap;"><span style="font-family:;" "=""><span style="font-family:Verdana;">from</span><b> <span style="color:#943634;"><a href="file:///C:/Users/test8/Desktop/7%E6%9C%88%20EPE13.7%20%E6%8F%92%E9%A1%B5%E7%A0%81%20%E4%BB%98%E5%96%9C%E4%BB%81%20%EF%BC%881%EF%BC%89/1-6202510.docx#f6"><span style="color:#943634;font-family:Verdana;">Figure</span><span style="color:#943634;font-family:Verdana;">s</span><span style="color:#943634;font-family:Verdana;"> 6</span><span style="color:#943634;font-family:Verdana;">(</span><span style="color:#943634;font-family:Verdana;">a</span><span style="color:#943634;font-family:Verdana;">)-(</span><span style="color:#943634;font-family:Verdana;">d</span><span style="color:#943634;font-family:Verdana;">)</span></a></span></b></span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">representing</span></span><span style="font-family:Verdana;"> the variations of the global solar radiation on the solstices and equinoxes as well as the 21 of the months of the year days understood show that: if τ</span><sub><span style="font-family:Verdana;">a </span></sub><span style="font-family:Verdana;">= 0 and </span><i><span style="font-family:Verdana;">X </span></i><span style="font-family:Verdana;">= 0, I</span><sub><span style="font-family:Verdana;">C </span></sub><span style="font-family:Verdana;">= 67.87%;if τ</span><sub><span style="font-family:Verdana;">a </span></sub><span style="font-family:Verdana;">= 0.5 and </span><i><span style="font-family:Verdana;">X </span></i><span style="font-family:Verdana;">= 0.5, I</span><sub><span style="font-family:Verdana;">C </span></sub><span style="font-family:Verdana;">= 21%;if τ</span><sub><span style="font-family:Verdana;">a </span></sub><span style="font-family:Verdana;">= 0.8 and </span><i><span style="font-family:Verdana;">X </span></i><span style="font-family:Verdana;">= 0.8, I</span><sub><span style="font-family:Verdana;">C </span></sub><span style="font-family:Verdana;">= 12% and if τ</span><sub><span style="font-family:Verdana;">a </span></sub><span style="font-family:Verdana;">= 1.5 and </span><i><span style="font-family:Verdana;">X </span></i><span style="font-family:Verdana;">= 1.5 then I</span><sub><span style="font-family:Verdana;">C </span></sub><span style="font-family:Verdana;">= 4%. These results show that desert aerosols significantly influence the global solar radiation received. Unfortunately, this influence lowers the productivity of the central solar PV in general.</span>
基金jointly supported by the National Key Research and Development Program of China [grant number2016YFE0201400]the Basic Research Program of the State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry,Institute of Atmospheric Physics,Chinese Academy of Sciences [grant number 7-082999]
文摘To realistically simulate the impacts of marine isoprene and primary organic aerosols (POA) on atmospheric chemistry, a unified model framework with online emissions, comprehensive treatment of gas-phase chemistry, and advanced aerosol microphysics is required. In this work, the global-through-urban WRF/Chem model (GU-WRF/Chem) implemented with the online emissions of marine isoprene and size-resolved marine POA is applied to examine such impacts. The net effect of these emissions was increased surface concentrations of isoprene and organic aerosols and decreased surfaced concentrations of hydroxyl radical and ozone over most marine regions. With the inclusion of these emissions, GU-WRF/Chem better predicted the surface concentrations of isoprene and organic aerosols and the aerosol number size distribution when compared to measurements in clean marine conditions.
文摘Contaminated or infected patients present a risk of cross-contamination for emergency responders, attending medical personnel and medical facilities as they enter a treatment facility. The controlled conditions of an aerosol test chamber are required to examine factors of contamination, decontamination, and cross-contamination. This study presents the design, construction, and a method for characterizing an aerosol test chamber for a full-sized manikin on a standard North Atlantic Treaty Organization litter. The methodology combined air velocity measurements, aerosol particle counts and size distributions, and computational fluid dynamics modeling to describe the chamber’s performance in three dimensions. This detailed characterization facilitates future experimental design by predicting chamber performance for a variety of patient-focused research.
基金supported by the National Key Research and Development Project of China (Grant No. 2016YFA0600604)the National Natural Science Foundation of China (Grant No. 41461144001 and No. 41861144016)the Youth Innovation Promotion Association of the Chinese Academy of Sciences (Grant No. 2014064)
文摘With the gradual yet unequivocal phasing out of ozone depleting substances(ODSs), the environmental crisis caused by the discovery of an ozone hole over the Antarctic has lessened in severity and a promising recovery of the ozone layer is predicted in this century. However, strong volcanic activity can also cause ozone depletion that might be severe enough to threaten the existence of life on Earth. In this study, a transport model and a coupled chemistry–climate model were used to simulate the impacts of super volcanoes on ozone depletion. The volcanic eruptions in the experiments were the 1991 Mount Pinatubo eruption and a 100 × Pinatubo size eruption. The results show that the percentage of global mean total column ozone depletion in the 2050 RCP8.5 100 × Pinatubo scenario is approximately 6% compared to two years before the eruption and 6.4% in tropics. An identical simulation, 100 × Pinatubo eruption only with natural source ODSs, produces an ozone depletion of 2.5% compared to two years before the eruption, and with 4.4% loss in the tropics. Based on the model results,the reduced ODSs and stratospheric cooling lighten the ozone depletion after super volcanic eruption.
基金National Fundamental Research Program of China (2011CB403202)National Natural Science Foundation of China (40675040)
文摘The International Centre for Theoretical Physics(ICTP,Italy) Regional Climate Model version 3.0(RegCM3) is used to simulate spatio-temporal distribution characteristics and radiative forcing(RF) of organic carbon(OC) aerosols in and around China.The preliminary simulation results show that OC aerosols are mostly concentrated in the area to the south of Yellow River and east of Tibetan Plateau.There is a decreasing trend of column burden of OC aerosols from south to north in China.The maximum value of column burden of OC aerosols is above 3 mg/m2 and located in the central and southern China,southeastern Tibet,and southwestern China's Yunnan,Guizhou,Sichuan provinces.The simulation on the seasonal variation shows that the maximum value of column burden of OC aerosols appears in winter and the secondary value is in spring and the minimum in summer.The RF of OC aerosols which varies seasonally is negative at the top of the atmosphere(TOA) and surface.The spatio-temporal characteristics of the RF of OC aerosols are basically consistent with that of IPCC,implying the high accuracy of the parameterization scheme for OC aerosols in RegCM3.
基金supported by the National Natural Science Foundation of China(NSFC)under Grant No.40005001 and the key laboratory of storm and disaster of Educational Department of China
文摘A one-dimensional 3rd-order turbulence closure model with size-resolved microphysics and radiative transfer has been developed for investigating aerosol and cloud interactions of the stratocumulus-topped marine boundary layer. A new method is presented for coupling between the dynamical model and the microphysical model. This scheme allows the liquid water related correlations to be directly calculated rather than parameterized. On 21 April 2001, a marine stratocumulus was observed by the Caesar aircraft over the west Pacific Rim south of Japan during the 2001 APEX/ACE-Asia field measurements. This cloud is simulated by the model we present here. The model results show that the general features of the stratocumulus-topped marine boundary layer predicted by the model are in agreement with the measurements. A new onboard cloud condensation nuclei (CCN) counter provides not only total CCN number concentration (as the traditional CCN counters do at a certain supersaturation) but also the CCN size distribution information. Using these CCN data, model responses to different CCN initial concentrations are examined. The model results are consistent with both observations and expectations. The numerical results show that the cloud microphysical properties are changed fundamentally by different initial CCN concentrations but the cloud liquid water content does not differ significantly. Different initial CCN loadings have large impacts on the evolution of cloud microstructure and radiation transfer while they have a modest effect on thermodynamics. Increased CCN concentration leads to significant decrease of cloud effective radius.
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-YW-Q11-03)the National Basic Research Program of China(2009CB421407)the National Natural Science Foundation of China(40805030)
文摘The authors used a high-resolution regional climate model(RegCM3) coupled with a chemistry/aerosol module to simulate East Asian climate in 2006 and to test the climatic impacts of aerosols on regionalscale climate.The direct radiative forcing and climatic effects of aerosols(dust,sulfate,black carbon,and organic carbon) were discussed.The results indicated that aerosols generally produced negative radiative forcing at the top-of-the-atmosphere(TOA) over most areas of East Asia.The radiative forcing induced by aerosols exhibited significant seasonal and regional variations,with the strongest forcing occurring in summer.The aerosol feedbacks on surface air temperature and precipitation were clear.Surface cooling dominated features over the East Asian continental areas,which varied in the approximate range of-0.5 to-2°C with the maximum up to-3-C in summer over the deserts of West China.The aerosols induced complicated variations of precipitation.Except in summer,the rainfall generally varied in the range of-1 to 1 mm d-1 over most areas of China.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41175105 and 40905055)the Key Project of Chinese Academy of Sciences (Grant No. kzcx1-yw-06-04)
文摘The Weather Research and Forecasting/Chemistry model (WRF-Chem) was updated by including pho- toexeited nitrogen dioxide (NO2) molecules, heterogeneous reactions on aerosol surfaces, and direct emissions of nitrous acid (HONO) in the Carbon-Bond Mechanism Z (CBM-Z). Five simulations were conducted to assess the effects of each new component and the three additional HONO sources on concentrations of major chemical components. We calculated percentage changes of major aerosol components and concentration ratios of gas NOy (NOyg) to NOy and particulate nitrates (NO3-) to NOy due to the three additional HONO sources in the North China Plain in August of 2007. Our results indicate that when the three additional HONO sources are included, WRF-Chem can reasonably reproduce the HONO observations. Heterogeneous reactions on aerosol surfaces are a key contributor to concentrations of HONO, nitrates (NO3-), ammonium (NH+), and PM2.5 (concentration of particulate matter of ≤2.5 um in the ambient air) across the North China Plain. The three additional HONO sources produced a -5% -20% increase in monthly mean daytime concentration ratios of NO3-/NOy, a -15%- 52% increase in maximum hourly mean concentration ratios of NO3-/NOy, and a -10% -50% increase in monthly mean concentrations of NOx and NH+ across large areas of the North China Plain. For the Bohai Bay, the largest hourly increases of NO3- exceeded 90%, of NH+ exceeded 80%, and of PM2.5 exceeded 40%, due to the three additional HONO sources. This implies that the three additional HONO sources can aggravate regional air pollution, further impair visibility, and enhance the incidence of haze in some industrialized regions with high emissions of NOx and particulate matter under favorable meteorological conditions.