scholarly journals Investigating the role of dust in ice nucleation within clouds and further effects on the regional weather system over East Asia – Part 2: modification of the weather system

2018 ◽  
Vol 18 (15) ◽  
pp. 11529-11545
Author(s):  
Lin Su ◽  
Jimmy C. H. Fung
Keyword(s):  
Surface Temperature ◽  
East Asia ◽  
South China ◽  
Radiative Forcing ◽  
Convective Precipitation ◽  
Radiative Effect ◽  
Weather System ◽  
Near Surface ◽  
Upper Troposphere ◽  
Atmospheric Instability

Abstract. An updated version of the Weather Research and Forecast model coupled with Chemistry (WRF-Chem) was applied to quantify and investigate the full effects of dust on the meteorological field over East Asia during March and April 2012. The performances of the model in simulating the shortwave and longwave radiation, surface temperature, and precipitation over East Asia are improved by incorporating the effects of dust in the simulations. The radiative forcing induced by the direct radiative effect of dust is greater than that by the dust-enhanced cloud radiative effect. The indirect effects of dust result in a substantial increase in ice clouds at the middle to upper troposphere and a reduction in liquid clouds at the low to mid-troposphere. The radiative forcing combined with the redistribution of atmospheric water vapor results in an overall decrease in near-surface temperature and an increase in temperature at the middle to upper troposphere over East Asia, leading to an inhibition of atmospheric instability over most land areas, but an enhancement of atmospheric instability over south China. Upon considering the effects of dust, convective precipitation exhibits an inhibition over areas from central to east China and an enhancement over south China. Meanwhile, the locations of non-convective precipitation are shifted due to the perturbation of cloud water path. The total amount of precipitation over East Asia remains unchanged; however, the precipitation locations are shifted. The precipitation can be enhanced or inhibited by up to 20 % at particular areas.

scholarly journals Investigating the role of dust in ice nucleation within clouds and further effects on the regional weather system over East Asia – Part II: modification of the weather system

2017 ◽  
Author(s):  
Lin Su ◽  
Jimmy C.H. Fung
Keyword(s):  
Surface Temperature ◽  
East Asia ◽  
South China ◽  
Indirect Effects ◽  
Convective Precipitation ◽  
Wave Radiation ◽  
Direct And Indirect Effects ◽  
Weather System ◽  
Near Surface ◽  
Atmospheric Instability

Abstract. An updated version of the Weather Research and Forecast model coupled with Chemistry (WRF-Chem) was applied to quantify and discuss the full effects of dust on the meteorological field over East Asia during March and April 2012. The performances of the model in simulating the short-wave and long-wave radiation, surface temperature, and precipitation over East Asia are improved by incorporating the effects of dust in the simulations. The radiative forcing induced by the dust-enhanced cloud radiative effect is over one order of magnitude larger than that induced by the direct effect of dust. The semi-direct and indirect effects of dust result in a substantial increase in mid- to high clouds, and a significant reduction in low clouds, leading to a decrease of near-surface temperature and an increase of temperature at the mid- to upper troposphere over East Asia. The spatial redistribution of atmospheric water vapor and modification of the vertical temperature profile over East Asia lead to an inhibition of atmospheric instability over most land areas, but an enhancement of atmospheric instability over South China and the ocean, resulting in a significant inhibition of convective precipitation in areas from central to East China, and a substantial enhancement of convective precipitation over South China. Meanwhile, non-convective precipitation is also reduced significantly over East Asia, as cloud droplets are hindered from growing large enough to form rain droplets, due to the semi-direct and indirect effects of dust. The total precipitation can be reduced or increased by up to 20 % or more.

scholarly journals Estimation of the terms acting on local 1 h surface temperature variations in Paris region: the specific contribution of clouds

2021 ◽  
Vol 21 (20) ◽  
pp. 15699-15723
Author(s):  
Oscar Javier Rojas Muñoz ◽  
Marjolaine Chiriaco ◽  
Sophie Bastin ◽  
Justine Ringard
Keyword(s):  
Heat Exchange ◽  
Surface Temperature ◽  
Radiative Forcing ◽  
Small Scale ◽  
Radiative Effect ◽  
Near Surface ◽  
Temperature Variations ◽  
Clear Sky ◽  
Hourly Temperature ◽  
Specific Contribution

Abstract. Local short-term temperature variations at the surface are mainly dominated by small-scale processes coupled through the surface energy balance terms, which are well known but whose specific contribution and importance on the hourly scale still need to be further analyzed. A method to determine each of these terms based almost exclusively on observations is presented in this paper, with the main objective being to estimate their importance in hourly near-surface temperature variations at the SIRTA observatory, near Paris. Almost all terms are estimated from the multi-year dataset SIRTA-ReOBS, following a few parametrizations. The four main terms acting on temperature variations are radiative forcing (separated into clear-sky and cloudy-sky radiation), atmospheric heat exchange, ground heat exchange, and advection. Compared to direct measurements of hourly temperature variations, it is shown that the sum of the four terms gives a good estimate of the hourly temperature variations, allowing a better assessment of the contribution of each term to the variation, with an accurate diurnal and annual cycle representation, especially for the radiative terms. A random forest analysis shows that whatever the season, clouds are the main modulator of the clear-sky radiation for 1 h temperature variations during the day and mainly drive these 1 h temperature variations during the night. Then, the specific role of clouds is analyzed exclusively in cloudy conditions considering the behavior of some classical meteorological variables along with lidar profiles. Cloud radiative effect in shortwave and longwave and lidar profiles show a consistent seasonality during the daytime, with a dominance of mid- and high-level clouds detected at the SIRTA observatory, which also affects near-surface temperatures and upward sensible heat flux. During the nighttime, despite cloudy conditions and having a strong cloud longwave radiative effect, temperatures are the lowest and are therefore mostly controlled by larger-scale processes at this time.

scholarly journals Simulation of dust aerosol and its regional feedbacks over East Asia using a regional climate model

2008 ◽  
Vol 8 (2) ◽  
pp. 4625-4667 ◽  
Author(s):  
D. F. Zhang ◽  
A. S. Zakey ◽  
X. J. Gao ◽  
F. Giorgi
Keyword(s):  
East Asia ◽  
Regional Climate Model ◽  
Radiative Forcing ◽  
Climate Model ◽  
Regional Climate ◽  
Surface Cooling ◽  
Near Surface ◽  
Dust Aerosols ◽  
Source Regions ◽  
Mass Load

Abstract. The ICTP regional climate model (RegCM3) coupled with a desert dust model is used to simulate the radiative forcing and related climate effects of dust aerosols over East Asia. Two sets of experiments encompassing the main dust producing months, February to May, for 10 years (1997–2006) are conducted and inter-compared, one without (Exp. 1) and one with (Exp. 2) the radiative effects of dust aerosols. The simulation results are evaluated against ground station and satellite data. The model captures the basic observed climatology over the area of interest. The spatial and temporal variations of near surface concentration, mass load, and emission of dust aerosols from the main source regions are reproduced by model, with the main model deficiency being an overestimate of dust amount over the source regions and underestimate downwind of these source areas. Both the top-of-the-atmosphere (TOA) and surface radiative fluxes are decreased by dust and this causes a surface cooling locally up to −1°C. The inclusion of dust radiative forcing leads to a reduction of dust emission in the East Asia source regions, which is mainly caused by an increase in local stability and a corresponding decrease in dust lifting. Our results indicate that dust effects should be included in the assessment of climate change over East Asia.

Modification of Near‐Surface Temperature Over East Asia Associated With Local‐Scale Paddy Irrigation

2019 ◽  
Vol 124 (5) ◽  
pp. 2665-2676 ◽  
Author(s):  
Shiori Sugimoto ◽  
Hiroshi G. Takahashi ◽  
Hirosato Sekiyama
Keyword(s):  
Surface Temperature ◽  
East Asia ◽  
Local Scale ◽  
Near Surface ◽  
Paddy Irrigation

Interaction between the Black Carbon Aerosol Warming Effect and East Asian Monsoon

2020 ◽  
Author(s):  
Bingliang Zhuang ◽  
Tijian Wang ◽  
Shu Li ◽  
Min Xie ◽  
Mengmeng Li ◽  
...  
Keyword(s):  
East Asia ◽  
Black Carbon ◽  
South China ◽  
Radiative Forcing ◽  
Asian Monsoon ◽  
Meridional Circulation ◽  
East Asian Monsoon ◽  
Regional Climate ◽  
East Asian ◽  
Black Carbon Aerosol

<p>Black carbon aerosol (BC) has a significant influence on regional climate changes due to its warming effect. Such changes will feedback to BC loadings. Here, the interactions between the BC warming effect and East Asian monsoon (EAM) in both winter (EAWM) and summer (EASM) are investigated using a regional climate model RegCM4, which essentially captures the EAM features and the BC variations in China. The seasonal mean BC optical depth is 0.021 over East Asia during winter, which is 10.5% higher than that during summer. Nevertheless, the BCs direct radiative forcing is 32% stronger during summer (+1.85 W/m<sup>2</sup>). The BC direct effect would induce lower air to warm by 0.11-0.12 K, which causes an meridional circulation anomaly associated with a cyclone at 20-30 <sup>o</sup>N and southerly anomalies at 850 hPa over East Asia. Consequently, the EAM circulation is weakened during winter but enhanced during summer. Precipitation is likely increased, especially in south China during summer (by 3.73%). Compared to BC changes due to EAM interannual variations, BC changes due to its warming effect are as important, but weaker. BC surface concentrations are decreased by 1~3% during both winter and summer, by 1~3%, while the columnar BC is increased in south China during winter. During the strongest monsoon years, the BC loadings are higher at lower latitudes than those during the weakest years, resulting in more southerly meridional circulation anomalies and BC feedbacks during both winter and summer. However, the interactions between the BC warming effect and EAWM/EASM are more intense during the weakest monsoon years.</p>

scholarly journals Source attribution of black carbon and its direct radiative forcing in China

2016 ◽  
Author(s):  
Yang Yang ◽  
Hailong Wang ◽  
Steven J. Smith ◽  
Po-Lun Ma ◽  
Philip J. Rasch
Keyword(s):  
Air Quality ◽  
East Asia ◽  
Black Carbon ◽  
Radiative Forcing ◽  
North China ◽  
Local Source ◽  
Near Surface ◽  
Direct Radiative Forcing ◽  
Non Local ◽  
Local Emissions

Abstract. The source attributions for mass concentration, haze formation, transport, and direct radiative forcing of black carbon (BC) in various regions of China are quantified in this study using the Community Earth System Model (CESM) with a source-tagging technique. Anthropogenic emissions are from the Community Emissions Data System that is newly developed for the Coupled Model Intercomparison Project Phase 6 (CMIP6). Over North China where the air quality is often poor, about 90 % of near-surface BC concentration is contributed by local emissions. 30 % of BC concentration over South China in winter can be attributed to emissions from North China and 10 % comes from sources outside China in spring. For other regions in China, BC is largely contributed from non-local sources. We further investigated potential factors that contribute to the poor air quality in China. During polluted days, a net inflow of BC transported from non-local source regions associated with anomalous winds plays an important role in increasing local BC concentrations. BC-containing particles emitted from East Asia can also be transported across the Pacific. Our model results show that emissions from inside and outside China are equally important for the BC outflow from East Asia, while emissions from China account for 7 % of BC concentration and 25 % in column burden in western United States in spring. Radiative forcing estimated shows that 66 % of the annual mean BC direct radiative forcing (2.3 W m−2) in China results from local emissions, and the remaining 34 % are contributed by emissions outside of China. Efficiency analysis shows that reduction in BC emissions over eastern China could benefit more on the regional air quality in China, especially in winter haze season.

scholarly journals Quantifying sources, transport, deposition, and radiative forcing of black carbon over the Himalayas and Tibetan Plateau

2015 ◽  
Vol 15 (11) ◽  
pp. 6205-6223 ◽  
Author(s):  
R. Zhang ◽  
H. Wang ◽  
Y. Qian ◽  
P. J. Rasch ◽  
R. C. Easter ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
East Asia ◽  
South Asia ◽  
Black Carbon ◽  
Radiative Forcing ◽  
Glacier Retreat ◽  
Modeling Framework ◽  
Near Surface ◽  
Geographical Regions ◽  
Source Receptor Relationships

Abstract. Black carbon (BC) particles over the Himalayas and Tibetan Plateau (HTP), both airborne and those deposited on snow, have been shown to affect snowmelt and glacier retreat. Since BC over the HTP may originate from a variety of geographical regions and emission sectors, it is essential to quantify the source–receptor relationships of BC in order to understand the contributions of natural and anthropogenic emissions and provide guidance for potential mitigation actions. In this study, we use the Community Atmosphere Model version 5 (CAM5) with a newly developed source-tagging technique, nudged towards the MERRA meteorological reanalysis, to characterize the fate of BC particles emitted from various geographical regions and sectors. Evaluated against observations over the HTP and surrounding regions, the model simulation shows a good agreement in the seasonal variation in the near-surface airborne BC concentrations, providing confidence to use this modeling framework for characterizing BC source–receptor relationships. Our analysis shows that the relative contributions from different geographical regions and source sectors depend on season and location in the HTP. The largest contribution to annual mean BC burden and surface deposition in the entire HTP region is from biofuel and biomass (BB) emissions in South Asia, followed by fossil fuel (FF) emissions from South Asia, then FF from East Asia. The same roles hold for all the seasonal means except for the summer, when East Asia FF becomes more important. For finer receptor regions of interest, South Asia BB and FF have the largest impact on BC in the Himalayas and central Tibetan Plateau, while East Asia FF and BB contribute the most to the northeast plateau in all seasons and southeast plateau in the summer. Central Asia and Middle East FF emissions have relatively more important contributions to BC reaching the northwest plateau, especially in the summer. Although local emissions only contribute about 10% of BC in the HTP, this contribution is extremely sensitive to local emission changes. Lastly, we show that the annual mean radiative forcing (0.42 W m−2) due to BC in snow outweighs the BC dimming effect (−0.3 W m−2) at the surface over the HTP. We also find strong seasonal and spatial variation with a peak value of 5 W m−2 in the spring over the northwest plateau. Such a large forcing of BC in snow is sufficient to cause earlier snow melting and potentially contribute to the acceleration of glacier retreat.

scholarly journals Source attribution of black carbon and its direct radiative forcing in China

2017 ◽  
Vol 17 (6) ◽  
pp. 4319-4336 ◽  
Author(s):  
Yang Yang ◽  
Hailong Wang ◽  
Steven J. Smith ◽  
Po-Lun Ma ◽  
Philip J. Rasch
Keyword(s):  
Air Quality ◽  
East Asia ◽  
Black Carbon ◽  
Radiative Forcing ◽  
North China ◽  
Eastern China ◽  
Coupled Model ◽  
Near Surface ◽  
Direct Radiative Forcing ◽  
Local Emissions

Abstract. The source attributions for mass concentration, haze formation, transport and direct radiative forcing of black carbon (BC) in various regions of China are quantified in this study using the Community Earth System Model (CESM) with a source-tagging technique. Anthropogenic emissions are from the Community Emissions Data System that is newly developed for the Coupled Model Intercomparison Project Phase 6 (CMIP6). Over north China where the air quality is often poor, about 90 % of near-surface BC concentration is contributed by local emissions. Overall, 35 % of BC concentration over south China in winter can be attributed to emissions from north China, and 19 % comes from sources outside China in spring. For other regions in China, BC is largely contributed from nonlocal sources. We further investigated potential factors that contribute to the poor air quality in China. During polluted days, a net inflow of BC transported from nonlocal source regions associated with anomalous winds plays an important role in increasing local BC concentrations. BC-containing particles emitted from East Asia can also be transported across the Pacific. Our model results show that emissions from inside and outside China are equally important for the BC outflow from East Asia, while emissions from China account for 8 % of BC concentration and 29 % in column burden in the western United States in spring. Radiative forcing estimates show that 65 % of the annual mean BC direct radiative forcing (2.2 W m−2) in China results from local emissions, and the remaining 35 % is contributed by emissions outside of China. Efficiency analysis shows that a reduction in BC emissions over eastern China could have a greater benefit for the regional air quality in China, especially in the winter haze season.

scholarly journals Global source attribution of sulfate concentration, direct and indirect radiative forcing

2017 ◽  
Author(s):  
Yang Yang ◽  
Hailong Wang ◽  
Steven J. Smith ◽  
Richard Easter ◽  
Po-Lun Ma ◽  
...  
Keyword(s):  
Southeast Asia ◽  
East Asia ◽  
South Asia ◽  
Central Asia ◽  
Southern Hemisphere ◽  
North Africa ◽  
Radiative Forcing ◽  
Sulfate Concentration ◽  
Near Surface ◽  
Indirect Radiative Forcing

Abstract. The global source-receptor relationships of sulfate concentration, direct and indirect radiative forcing (DRF and IRF) from sixteen regions/sectors for years 2010–2014 are examined in this study through utilizing a sulfur source-tagging capability implemented in the Community Earth System Model (CESM) with winds nudged to reanalysis data. Sulfate concentrations are mostly contributed by local emissions in regions with high emissions, while over regions with relatively low SO2 emissions, the near-surface sulfate concentrations are primarily attributed to non-local sources from long-range transport. The export of SO2 and sulfate from Europe contributes 16–20 % of near-surface sulfate concentrations over North Africa, Russia/Belarus/Ukraine (RBU) region and Central Asia. Sources from the Middle East account for 15–24 % of sulfate over North Africa, Southern Africa and Central Asia in winter and autumn, and 19 % over South Asia in spring. Sources in RBU account for 21–42 % of sulfate concentrations over Central Asia. East Asia accounts for about 50 % of sulfate over Southeast Asia in winter and autumn, 15 % over RBU in summer, and 11 % over North America in spring. South Asia contributes to 11–24 % of sulfate over Southeast Asia in winter and spring. Regional source efficiencies of sulfate concentrations are higher over regions with dry atmospheric conditions and less export, suggesting that lifetime of aerosols, together with regional export, is important in determining regional air quality. The simulated global total sulfate DRF is −0.42 W m−2, with  0.31 W m−2 contributed by anthropogenic sulfate and −0.11 W m−2 contributed by natural sulfate, relative to a state with no sulfur emissions. In the Southern Hemisphere tropics, dimethyl sulfide (DMS) contributes 17–84 % to the total DRF. East Asia has the largest contribution of 20–30 % over the Northern Hemisphere mid- and high-latitudes. A 20 % perturbation of sulfate and its precursor emissions gives a sulfate incremental IRF of −0.44 W m−2. DMS has the largest contribution, explaining −0.23 W m−2 of the global sulfate incremental IRF. Incremental IRF over regions in the Southern Hemisphere with low background aerosols is more sensitive to emission perturbation than those over the polluted Northern Hemisphere.

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