scholarly journals Solar Brightening/Dimming over China’s Mainland: Effects of Atmospheric Aerosols, Anthropogenic Emissions, and Meteorological Conditions

2020 ◽  
Vol 13 (1) ◽  
pp. 88
Author(s):  
Hejin Fang ◽  
Wenmin Qin ◽  
Lunche Wang ◽  
Ming Zhang ◽  
Xuefang Yang
Keyword(s):  
Atmospheric Aerosols ◽  
Southern China ◽  
Influencing Factor ◽  
Precipitable Water ◽  
Northwest China ◽  
Meteorological Conditions ◽  
Anthropogenic Emissions ◽  
Main Role ◽  
Surface Solar Radiation ◽  
Climate Change Research

Surface solar radiation (SSR) is the main factor affecting the earth’s climate and environment and its variations and the reason for these variations are an important part of climate change research. In this research, we investigated the long-term variations of SSR during 1984–2016 and the quantitative influences of atmospheric aerosols, anthropogenic emissions, and meteorological conditions on SSR over China’s mainland. The results show the following: (1) The annual average SSR values had a decline trend at a rate of −0.371 Wm−2 yr−1 from 1984 to 2016 over China. (2) The aerosol optical depth (AOD) plays the main role in inducing variations in SSR over China, with r values of −0.75. Moreover, there are marked regional differences in the influence of anthropogenic emissions and meteorological conditions on SSR trends. (3) From a regional perspective, AOD is the main influencing factor on SSR in northeast China (NEC), Yunnan Plateau and surrounding regions (YPS), North China (NC), and Loess Plateau (LP), with r values of −0.65, −0.60, −0.89, and −0.50, respectively. However, the main driving factors for SSR in northwest China (NWC) are “in cloud optical thickness of all clouds” (TAUTOT) (−0.26) and black carbon (BC) anthropogenic emissions (−0.21). TAUTOT (−0.39) and total precipitable water vapor (TQV) (−0.29) are the main influencing factors of SSR in the middle-lower Yangtze Plain (MYP). The main factors that influence SSR in southern China (SC) are surface pressure (PS) (−0.66) and AOD (−0.43). This research provides insights in understanding the variations of SSR and its relationships with anthropogenic conditions and meteorological factors.

Back to the Future: Reducing Atmospheric Particulate Matter Levels to Improve Human Health

2021 ◽  
Author(s):  
Spyros Pandis
Keyword(s):  
Particulate Matter ◽  
Atmospheric Aerosols ◽  
Atmospheric Chemistry ◽  
Control Strategy ◽  
Atmospheric Particulate Matter ◽  
Anthropogenic Emissions ◽  
The Us ◽  
Negative Impacts ◽  
Predictive Understanding ◽  
Physical And Chemical

<p>The human development of our planet has a variety of negative impacts on the composition of its atmosphere at every scale – locally, regionally, and even globally. One of these dramatic changes has been the increase in the mass concentrations of sub-micrometer particles by one to sometimes two orders of magnitude over populated areas in the Northern Hemisphere. These atmospheric aerosols can cause serious health problems, reduce visibility, contribute to acidic deposition and material damage, but are also cooling the planet by reflecting sunlight back to space. Atmospheric chemistry occurs within a fabric of complicated atmospheric dynamics and physics. This interplay often results in nonlinear and often counterintuitive changes of the system when anthropogenic emissions change. A major goal of our research has been to gain a predictive understanding of the physical and chemical processes that govern the dynamics, size, and chemical composition of atmospheric aerosols.</p><p>To illustrate the advances in the experimental techniques and theoretical tools in atmospheric aerosol science, we will go back to the beginning of the 21<sup>st</sup> century and we will revisit the design a particulate matter control strategy for the Eastern US based on the data, knowledge, and tools available at that time. We will then look at the effects of the parts of this control strategy that have been materialized and their effects on public health using the current understanding. Finally, we will look forward in ways of further improving air quality in the US and Europe.</p>

scholarly journals Properties of aerosols and formation mechanisms over southern China during the monsoon season

2016 ◽  
Author(s):  
Weihua Chen ◽  
Xuemei Wang ◽  
Jason Blake Cohen ◽  
Shengzhen Zhou ◽  
Zhisheng Zhang ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Atmospheric Aerosols ◽  
Transport Model ◽  
Atmospheric Transport ◽  
Southern China ◽  
Monsoon Season ◽  
Sea Salt ◽  
Urban Site ◽  
Chemical Components ◽  
Formation Mechanisms

Abstract. Measurements of size-resolved aerosols from 0.25 to 18 μm were conducted at three sites (urban, suburban and background sites) and used in tandem with an atmospheric transport model to study the size distribution and formation of atmospheric aerosols in southern China during the monsoon season (May–June) in 2010. The mass distribution showed the majority of chemical components were found in the smaller size bins (< 2.5 μm). Sulfate, was found to be strongly correlated with aerosol water, and anti-correlated with atmospheric SO2, hinting at aqueous-phase reactions being the main formation pathway. Nitrate was the only major species that showed a bi-modal distribution at the urban site, and was dominated by the coarse mode in the other two sites, suggesting that an important component of nitrate formation is chloride depletion of sea salt transported from the South China Sea. In addition to these aqueous-phase reactions and interactions with sea salt aerosols, new particle formation, chemical aging, and long-range transport from upwind urban or biomass burning regions were also found to be important in at least some of the sights on some of the days. This work therefore summarizes the different mechanisms that significantly impact the aerosol chemical composition during the Monsoon over southern China.

Changes in the Amplitude of the Temperature Annual Cycle in China and Their Implication for Climate Change Research

2011 ◽  
Vol 24 (20) ◽  
pp. 5292-5302 ◽  
Author(s):  
Cheng Qian ◽  
Congbin Fu ◽  
Zhaohua Wu
Keyword(s):  
Climate Change ◽  
Annual Cycle ◽  
Linear Trend ◽  
Surface Air Temperature ◽  
Mean Amplitude ◽  
Warming Trend ◽  
Ensemble Empirical Mode Decomposition ◽  
Surface Solar Radiation ◽  
Climate Change Research ◽  
Annual Cycles

Abstract Climate change is not only reflected in the changes in annual means of climate variables but also in the changes in their annual cycles (seasonality), especially in the regions outside the tropics. In this study, the ensemble empirical mode decomposition (EEMD) method is applied to investigate the nonlinear trend in the amplitude of the annual cycle (which contributes 96% of the total variance) of China’s daily mean surface air temperature for the period 1961–2007. The results show that the variation and change in the amplitude are significant, with a peak-to-peak annual amplitude variation of 13% (1.8°C) of its mean amplitude and a significant linear decrease in amplitude by 4.6% (0.63°C) for this period. Also identified is a multidecadal change in amplitude from significant decreasing (−1.7% decade−1 or −0.23°C decade−1) to significant increasing (2.2% decade−1 or 0.29°C decade−1) occurring around 1993 that overlaps the systematic linear trend. This multidecadal change can be mainly attributed to the change in surface solar radiation, from dimming to brightening, rather than to a warming trend or an enhanced greenhouse effect. The study further proposes that the combined effect of the global dimming–brightening transition and a gradual increase in greenhouse warming has led to a perceived warming trend that is much larger in winter than in summer and to a perceived accelerated warming in the annual mean since the early 1990s in China. It also notes that the deseasonalization method (considering either the conventional repetitive climatological annual cycle or the time-varying annual cycle) can also affect trend estimation.

scholarly journals Abundant Precipitation in Qilian Mountains Generated from the Recycled Moisture over the Adjacent Arid Hexi Corridor, Northwest China

Water ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 3354
Author(s):  
Zhihua Zhang ◽  
Qiudong Zhao ◽  
Shiqiang Zhang
Keyword(s):  
Water Vapor ◽  
Water Cycle ◽  
Precipitable Water ◽  
Northwest China ◽  
Hexi Corridor ◽  
Qilian Mountains ◽  
Mountain Areas ◽  
Reanalysis Dataset ◽  
Weather Forecasts ◽  
Endorheic Basin

The observed precipitation was suggestive of abundant precipitation in upstream Qilian mountains and low precipitation in the downstream oasis and desert in an endorheic basin. However, precipitation in mountains generated from the recycled moisture over oasis and desert areas has rarely been studied. The climatological patterns of water vapor from 1980 to 2017 in the Qilian Mountain Region (QMR) and Hexi Corridor Region (HCR) were investigated by the European Centre for Medium-Range Weather Forecasts Interim reanalysis dataset and the Modern-Era Retrospective Analysis for Research and Application, Version 2 reanalysis dataset. The results suggest that the precipitable water content decreases from the adjacent to the mountain areas. There are two channels that transport water vapor from the HCR to the QMR in the low troposphere (surface—600 hPa), suggesting that parts of recycled moisture generated from evapotranspiration over the oasis and desert of the HCR is transported to the QMR, contributing to the abundant precipitation in the QMR. This indicates that the transport mechanism is probably because of the “cold and wet island effect” of the cryosphere in QMR. This is likely one of the essential mechanisms of the water cycle in endorheic river basins, which has rarely been reported.

scholarly journals China’s emission control strategies have suppressed unfavorable influences of climate on wintertime PM2.5 concentrations in Beijing since 2002

2020 ◽  
Author(s):  
Meng Gao ◽  
Kaili Lin ◽  
Shiqing Zhang ◽  
Ken kin lam Yung
Keyword(s):  
Control Strategies ◽  
Emission Control ◽  
Field Measurements ◽  
Meteorological Conditions ◽  
Control Measures ◽  
Anthropogenic Emissions ◽  
Recent Climate ◽  
Decadal Variations ◽  
Haze Days ◽  
Emission Control Measures

&lt;p&gt;Severe wintertime PM2.5 pollution in Beijing has been receiving increasing worldwide attention, yet the decadal variations remain relatively unexplored. Combining field measurements and model simulations, we quantified the relative influences of anthropogenic emissions and meteorological conditions on PM2.5 concentrations in Beijing overwinters of 2002-2016. Between the winters of 2011 and 2016, stringent emission control measures resulted in a 21% decrease in mean mass concentrations of PM2.5 in Beijing, with 7 fewer haze days per winter on average. Given the overestimation of PM2.5 by model, the effectiveness of stringent emission control measures might have been slightly overstated. With fixed emissions, meteorological conditions over the study period would have led to an increase of haze in Beijing, but the strict emission control measures have suppressed the unfavorable influences of recent climate. The unfavorable meteorological conditions are attributed to the weakening of the East Asia Winter Monsoon associated particularly with an increase in pressure associated with the Aleutian low.&lt;/p&gt;

scholarly journals Chemical and meteorological influences on the lifetime of NO<sub>3</sub> at a semi-rural mountain site during PARADE

2016 ◽  
Vol 16 (8) ◽  
pp. 4867-4883 ◽  
Author(s):  
N. Sobanski ◽  
M. J. Tang ◽  
J. Thieser ◽  
G. Schuster ◽  
D. Pöhler ◽  
...  
Keyword(s):  
Loss Rate ◽  
Trace Gases ◽  
Meteorological Conditions ◽  
Biogenic Emissions ◽  
Anthropogenic Emissions ◽  
Air Masses ◽  
Mixing Ratios ◽  
Criegee Intermediates ◽  
Mountain Site ◽  
Meteorological Influences

Abstract. Through measurements of NO2, O3 and NO3 during the PARADE campaign (PArticles and RAdicals, Diel observations of mEchanisms of oxidation) in the German Taunus mountains we derive nighttime steady-state lifetimes (τss) of NO3 and N2O5. During some nights, high NO3 (∼ 200 pptv) and N2O5 (∼ 1 ppbv) mixing ratios were associated with values of τss that exceeded 1 h for NO3 and 3 h for N2O5 near the ground. Such long boundary-layer lifetimes for NO3 and N2O5 are usually only encountered in very clean/unreactive air masses, whereas the PARADE measurement site is impacted by both biogenic emissions from the surrounding forest and anthropogenic emissions from the nearby urbanised/industrialised centres. Measurement of several trace gases which are reactive towards NO3 indicates that the inferred lifetimes are significantly longer than those calculated from the summed loss rate. Several potential causes for the apparently extended NO3 and N2O5 lifetimes are examined, including additional routes to formation of NO3 and the presence of a low-lying residual layer. Overall, the most likely cause of the anomalous lifetimes are related to the meteorological conditions, though additional NO3 formation due to reactions of Criegee intermediates may contribute.

scholarly journals Studies of saharan dust intrusions over bucharest using ceilometer’s measurements and satellite data

2018 ◽  
Vol 176 ◽  
pp. 11004
Author(s):  
Denisa Urlea ◽  
Andreea Boscornea ◽  
Sorin Nicolae Vâjâiac ◽  
Florica Ţoancă ◽  
Nicu Barbu ◽  
...  
Keyword(s):  
Precipitable Water ◽  
Meteorological Conditions ◽  
Saharan Dust ◽  
Wind Flow ◽  
Model Output ◽  
Atmospheric Parameters ◽  
Output Data ◽  
Dominant Direction ◽  
Saharan Dust Intrusions

Three case studies of Saharan dust intrusions over southern Romania were performed. For these studies the database from the ceilometers located at Magurele and Strejnic was used. In addition, the meteorological conditions were analyzed using the WLK Catalogue based on the Objektive Wetterlagenklassifikation classification of the weather types [1]. This catalogue uses information from three basic tropospheric levels: 925, 700 and 500 hPa, and information on the precipitable water content over the entire atmosphere column. Geopotential fields at 925hPa and 500hPa are used for establishing the cyclonicity or anticyclonicity, while the U and V components of wind at 700hPa for establishing the dominant direction of the wind flow. For better understanding of the atmospheric parameters we performed HYSPLIT dispersion and trajectories analysis in conjunction with DREAM model output data.

scholarly journals GEM/POPs: a global 3-D dynamic model for semi-volatile persistent organic pollutants – Part 1: Model description and evaluations of air concentrations

2007 ◽  
Vol 7 (15) ◽  
pp. 4001-4013 ◽  
Author(s):  
S. L. Gong ◽  
P. Huang ◽  
T. L. Zhao ◽  
L. Sahsuvar ◽  
L. A. Barrie ◽  
...  
Keyword(s):  
Organic Pollutants ◽  
Persistent Organic Pollutants ◽  
Atmospheric Aerosols ◽  
Weather Forecasting ◽  
Model Description ◽  
Forecasting Model ◽  
Anthropogenic Emissions ◽  
Surface Areas ◽  
Aerosol Module ◽  
Year 2000

Abstract. GEM/POPs was developed to simulate the transport, deposition and partitioning of semi-volatile persistent organic pollutants (POPs) in the atmosphere within the framework of Canadian weather forecasting model GEM. In addition to the general processes such as anthropogenic emissions, atmosphere/water and atmosphere/soil exchanges, GEM/POPs incorporates a dynamic aerosol module to provide the aerosol surface areas for the semi-volatile POPs to partition between gaseous and particle phases and a mechanism for particle-bound POPs to be removed. Simulation results of three PCBs (28, 153 and 180) for the year 2000 indicate that the model captured the main features of global atmospheric PCBs when compared with observations from EMEP, IADN and Alert stations. The annual averaged concentrations and the fractionation of the three PCBs as a function of latitudes agreed reasonably well with observations. The impacts of atmospheric aerosols on the transports and partitioning of the three PCBs are reasonably simulated. The ratio of particulate to gaseous PCBs in the atmospheric column ranges from less than 0.1 for PCB28 to as high as 100 for PCB180, increasing from the warm lower latitudes to the cold high latitudes. Application of GEM/POPs in a study of the global transports and budgets of various PCBs accompanies this paper.

scholarly journals Impact of buildings on surface solar radiation over urban Beijing

2016 ◽  
Vol 16 (9) ◽  
pp. 5841-5852 ◽  
Author(s):  
Bin Zhao ◽  
Kuo-Nan Liou ◽  
Yu Gu ◽  
Cenlin He ◽  
Wee-Liang Lee ◽  
...  
Keyword(s):  
Atmospheric Aerosols ◽  
Early Morning ◽  
Solar Flux ◽  
Grid Resolution ◽  
Building Structures ◽  
Atmospheric Models ◽  
Urban Dispersion ◽  
Surface Solar Radiation ◽  
Plane Parallel ◽  
The Impact

Abstract. The rugged surface of an urban area due to varying buildings can interact with solar beams and affect both the magnitude and spatiotemporal distribution of surface solar fluxes. Here we systematically examine the impact of buildings on downward surface solar fluxes over urban Beijing by using a 3-D radiation parameterization that accounts for 3-D building structures vs. the conventional plane-parallel scheme. We find that the resulting downward surface solar flux deviations between the 3-D and the plane-parallel schemes are generally ±1–10 W m−2 at 800 m grid resolution and within ±1 W m−2 at 4 km resolution. Pairs of positive–negative flux deviations on different sides of buildings are resolved at 800 m resolution, while they offset each other at 4 km resolution. Flux deviations from the unobstructed horizontal surface at 4 km resolution are positive around noon but negative in the early morning and late afternoon. The corresponding deviations at 800 m resolution, in contrast, show diurnal variations that are strongly dependent on the location of the grids relative to the buildings. Both the magnitude and spatiotemporal variations of flux deviations are largely dominated by the direct flux. Furthermore, we find that flux deviations can potentially be an order of magnitude larger by using a finer grid resolution. Atmospheric aerosols can reduce the magnitude of downward surface solar flux deviations by 10–65 %, while the surface albedo generally has a rather moderate impact on flux deviations. The results imply that the effect of buildings on downward surface solar fluxes may not be critically significant in mesoscale atmospheric models with a grid resolution of 4 km or coarser. However, the effect can play a crucial role in meso-urban atmospheric models as well as microscale urban dispersion models with resolutions of 1 m to 1 km.

scholarly journals Foreign and domestic contributions to springtime ozone over China

2018 ◽  
Vol 18 (15) ◽  
pp. 11447-11469 ◽  
Author(s):  
Ruijing Ni ◽  
Jintai Lin ◽  
Yingying Yan ◽  
Weili Lin
Keyword(s):  
Southern China ◽  
Surface Ozone ◽  
Coupled Model ◽  
Lower Troposphere ◽  
Emission Source ◽  
Anthropogenic Emissions ◽  
Source Attribution ◽  
Global Emission ◽  
Source Regions ◽  
Northern Border

Abstract. China is facing a severe ozone problem, but the origin of its ozone remains unclear. Here we use a GEOS-Chem based global–regional two-way coupled model system to quantify the individual contributions of eight emission source regions worldwide to springtime ozone in 2008 over China. The model reproduces the observed ozone from 31 ground sites and various aircraft and ozonesonde measurements in China and nearby countries, with a mean bias of 10 %–15 % both near the surface and in the troposphere. We then combine zero-out simulations, tagged ozone simulations, and a linear weighting approach to account for the effect of nonlinear chemistry on ozone source attribution. We find considerable contributions of total foreign anthropogenic emissions to surface ozone over China (2–11 ppb). For ozone of anthropogenic origin averaged over China, foreign regions together contribute 40 %–60 % below the height of 2 km and 85 % in the upper troposphere. For total ozone contributed by foreign anthropogenic emissions over China at various heights, the portion of transboundary ozone produced within foreign emission source regions is less than 50 %, with the rest produced by precursors transported out of those source regions. Japan and Korea contribute 0.6–2.1 ppb of surface ozone over the east coastal regions. Southeast Asia contributes 1–5 ppb over much of southern China and South Asia contributes up to 5–10 ppb of surface ozone over the border of southwestern China; and their contributions increase with height due to strong upwelling over the source regions. The European contribution reaches 2.1–3.0 ppb for surface ozone over the northern border of China and 1.5 ppb in the lower troposphere averaged over China. North America contributes 0.9–2.7 ppb of surface ozone over most of China (1.5–2.1 ppb over the North China Plain), with a China average at 1.5–2.5 ppb at different heights below 8 km, due to its large anthropogenic emissions and the transport-favorable midlatitude westerly wind. In addition to domestic emission control, global emission reduction is critical for China's ozone mitigation.

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