Black Carbon in the Near-Surface Atmosphere Far Away from Emission Sources: Comparison of Measurements and MERRA-2 Reanalysis Data

This study proposes an improved approach for monitoring the spatial concentrations of hourly particulate matter less than 2.5 μm in diameter (PM2.5) via a deep neural network (DNN) using geostationary ocean color imager (GOCI) images and unified model (UM) reanalysis data over the Korean Peninsula. The DNN performance was optimized to determine the appropriate training model structures, incorporating hyperparameter tuning, regularization, early stopping, and input and output variable normalization to prevent training dataset overfitting. Near-surface atmospheric information from the UM was also used as an input variable to spatially generalize the DNN model. The retrieved PM2.5 from the DNN was compared with estimates from random forest, multiple linear regression, and the Community Multiscale Air Quality model. The DNN demonstrated the highest accuracy compared to that of the conventional methods for the hold-out validation (root mean square error (RMSE) = 7.042 μg/m3, mean bias error (MBE) = −0.340 μg/m3, and coefficient of determination (R2) = 0.698) and the cross-validation (RMSE = 9.166 μg/m3, MBE = 0.293 μg/m3, and R2 = 0.49). Although the R2 was low due to underestimated high PM2.5 concentration patterns, the RMSE and MBE demonstrated reliable accuracy values (<10 μg/m3 and 1 μg/m3, respectively) for the hold-out validation and cross-validation.

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Basin-Wide Connections of Upper-Ocean Temperature Variability in the Equatorial Indian Ocean

Journal of Climate ◽

10.1175/jcli-d-20-0419.1 ◽

2021 ◽

pp. 1-50

Author(s):

Ge Song ◽

Bohua Huang ◽

Rongcai Ren ◽

Zeng-Zhen Hu

Keyword(s):

Indian Ocean ◽

Equatorial Indian Ocean ◽

Reanalysis Data ◽

Upper Ocean ◽

Ocean Temperature ◽

Ocean Reanalysis ◽

Near Surface ◽

Surface Warming ◽

Transition Mechanism ◽

Wide Range

AbstractIn this paper, the interannual variability of upper-ocean temperature in the equatorial Indian Ocean (IO) and its basin-wide connections are investigated using 58-year (1958-2015) comprehensive monthly mean ocean reanalysis data. Three leading modes of an empirical orthogonal function (EOF) analysis dominate the variability of upper-ocean temperature in the equatorial IO in a wide range of timescales. A coherent interannual band within the first two EOF modes identifies an oscillation between the zonally tilting thermocline across the equatorial IO in its peak phases and basin-wide displacement of the equatorial thermocline in its transitional phases. Consistent with the recharge oscillation paradigm, this oscillation is inherent of the equatorial IO with a quasi-periodicity around 15 months, in which the wind-induced off-equatorial Rossby waves near 5°S-10°S provide the phase-transition mechanism. This intrinsic IO oscillation provides the biennial component in the observed IOD variations. The third leading mode shows a nonlinear long-term trend of the upper-ocean temperature, including the near-surface warming along the equatorial Indian Ocean, accompanied by cooling trend in the lower thermocline originating further south. Such vertical contrary trends may lead to an enhanced stratification in the equatorial IO.

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Variations of the electric field and current in the near-surface atmosphere during magnetic storms

10.1117/12.2601975 ◽

2021 ◽

Author(s):

Svetlana A. Riabova ◽

Yaroslav O. Romanovsky ◽

Alexander A. Spivak

Keyword(s):

Electric Field ◽

Magnetic Storms ◽

Near Surface ◽

Surface Atmosphere

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Dome effect of black carbon and its key influencing factors: A one-dimensional modelling study

10.5194/acp-2017-967 ◽

2017 ◽

Author(s):

Zilin Wang ◽

Xin Huang ◽

Aijun Ding

Keyword(s):

Boundary Layer ◽

Air Pollution ◽

Black Carbon ◽

Rural Areas ◽

Land Surface ◽

Critical Role ◽

Aerosol Layer ◽

Near Surface ◽

Haze Pollution ◽

The Impact

Abstract. Black carbon (BC) has been identified to play a critical role in aerosol-planet boundary layer (PBL) interaction and further deterioration of near-surface air pollution in megacities, which has been named as its dome effect. However, the impacts of key factors that influence this effect, such as the vertical distribution and aging processes of BC, and also the underlying land surface, have not been quantitatively explored yet. Here, based on available in-situ measurements of meteorology and atmospheric aerosols together with the meteorology-chemistry online coupled model, WRF-Chem, we conduct a set of parallel simulations to quantify the roles of these factors in influencing the BC's dome effect and surface haze pollution, and discuss the main implications of the results to air pollution mitigation in China. We found that the impact of BC on PBL is very sensitive to the altitude of aerosol layer. The upper level BC, especially those near the capping inversion, is more essential in suppressing the PBL height and weakening the turbulence mixing. The dome effect of BC tends to be significantly intensified as BC aerosol mixed with scattering aerosols during winter haze events, resulting in a decrease of PBL height by more than 25 %. In addition, the dome effect is more substantial (up to 15 %) in rural areas than that in the urban areas with the same BC loading, indicating an unexpected regional impact of such kind of effect to air quality in countryside. This study suggests that China's regional air pollution would greatly benefit from BC emission reductions, especially those from the elevated sources from the chimneys and also the domestic combustions in rural areas, through weakening the aerosol-boundary layer interactions that triggered by BC.

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The composition of Europa's near-surface atmosphere

Proceedings of the International Astronomical Union ◽

10.1017/s1743921308021856 ◽

2008 ◽

Vol 4 (S251) ◽

pp. 327-328

Author(s):

Mau C. Wong ◽

Tim Cassidy ◽

Robert E. Johnson

Keyword(s):

Solar System ◽

Surface Composition ◽

Near Surface ◽

Water Ice ◽

Model Studies ◽

Surface Atmosphere ◽

Jovian Magnetosphere ◽

Ice Surface ◽

Geophysical Phenomenon ◽

Inorganic Species

AbstractThe presence of an undersurface ocean renders Europa as one of the few planetary bodies in our Solar System that has been conjectured to have possibly harbored life. Some of the organic and inorganic species present in the ocean underneath are expected to transport upwards through the relatively thin ice crust and manifest themselves as impurities of the water ice surface. For this reason, together with its unique dynamic atmosphere and geological features, Europa has attracted strong scientific interests in past decades.Europa is imbedded inside the Jovian magnetosphere, and, therefore, is constantly subjected to the immerse surrounding radiations, similar to the other three Galilean satellites. The magnetosphere-atmosphere-surface interactions form a complex system that provides a multitude of interesting geophysical phenomenon that is unique in the Solar System. The atmosphere of Europa is thought to have created by, mostly, charged particles sputtering of surface materials. Consequently, the study of Europa's atmosphere can be used as a tool to infer the surface composition. In this paper, we will discuss our recent model studies of Europa's near-surface atmosphere. In particular, the abundances and distributions of the dominant O2 and H2O species, and of other organic and inorganic minor species will be addressed.

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Ozone and Oxides of Sulfur and Nitrogen in the Near-Surface Atmosphere above the Baikal Natural Territory

The Bulletin of Irkutsk State University Series Earth Sciences ◽

10.26516/2073-3402.2018.24.111 ◽

2018 ◽

Vol 24 ◽

pp. 111-123

Author(s):

O. I. Khuriganova ◽

◽

V. A. Obolkin ◽

V. L. Potemkin ◽

L. P. Golobokova ◽

...

Keyword(s):

Near Surface ◽

Surface Atmosphere ◽

Natural Territory

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A trajectory analysis of atmospheric transport of black carbon aerosols to Canadian High Arctic in winter and spring (1990–2005)

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-10-2221-2010 ◽

2010 ◽

Vol 10 (2) ◽

pp. 2221-2244 ◽

Cited By ~ 2

Author(s):

L. Huang ◽

S. L. Gong ◽

S. Sharma ◽

D. Lavoué ◽

C. Q. Jia

Keyword(s):

Regression Model ◽

Black Carbon ◽

North American ◽

Emission Intensity ◽

Atmospheric Transport ◽

High Arctic ◽

The Arctic ◽

Canadian High Arctic ◽

Near Surface ◽

Annual Variations

Abstract. Black carbon (BC) particles accumulated in the Arctic troposphere and deposited over snow have significant effects on radiative forcing of the Arctic regional climate. Applying cluster analysis technique on 10-day backward trajectories, transport pathways affecting Alert (82.5° N, 62.5° W), Nunavut in Canada are identified in this work, along with the associated transport frequency. Based on the atmospheric transport frequency and the estimated BC emission intensity from surrounding regions, a linear regression model is constructed to investigate the inter-annual variations of BC observed at Alert in January and April, representative of winter and spring respectively, between 1990 and 2005. Strong correlations are found between BC concentrations predicted with the regression model and measured at Alert for both seasons (R2 equals 0.77 and 0.81 for winter and spring, respectively). Results imply that atmospheric transport and BC emission are the major contributors to the inter-annual variations in BC concentrations observed at Alert in the cold seasons for the 16-year period. Based on the regression model the relative contributions of regional BC emissions affecting Alert are attributed to the Eurasian sector, composed of the European Union and the former USSR, and the North American sector. Considering both seasons, the model suggests that Eurasia is the major contributor to the near-surface BC levels at the Canadian High Arctic site with an average contribution of over 85% during the 16-year period. In winter, the atmospheric transport of BC aerosols from Eurasia is found to be even more predominant with a multi-year average of 94%. The model estimates smaller contribution from the Eurasian sector in spring (70%) than that in winter. It is also found that the change in Eurasian contributions depends mainly on the reduction of emission intensity, while the changes in both emission and atmospheric transport contributed to the inter-annual variation of North American contributions.

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