Abstract

This paper gives an overview of the current understanding of the observations of black carbon (BC) in snow and ice, and the estimates of BC deposition and its radiative forcing over the Arctic. Both of the observations and model results show that, in spring, the average BC concentration and the resulting radiative forcing in Russian Arctic > Canadian and Alaskan Arctic > Arctic Ocean and Greenland. The observed BC concentration presented a significant decrease trend from the Arctic coastal regions to the center of Arctic Ocean. In summer, due to the combined effects of BC accumulation and enlarged snow grain size, the averaged radiative forcing per unit area over the Arctic Ocean is larger than that over each sector of the Arctic in spring. However, because summer sea ice is always covered by a large fraction of melt ponds, the role of BC in sea ice albedo evolution during this period is secondary. Multi-model mean results indicate that the annual mean radiative forcing from all sources of BC in snow and ice over the Arctic was ∼0.17 W m−2 . Wet deposition is the dominant removal mechanism in the Arctic, which accounts for more than 90% of the total deposition. In the last part, we discuss the uncertainties in present modeling studies, and suggest potential approaches to reduce the uncertainties.

Abstract

A regional climate model (RegCM4.3.4) coupled with an aerosol–snow/ice feedback module was used to simulate the deposition of anthropogenic light-absorbing impurities in snow/ice and the potential radiative feedback of black carbon (BC) on temperature and snow cover over the Tibetan Plateau (TP) in 1990–2009. Two experiments driven by ERA-interim reanalysis were performed, i.e., with and without aerosol–snow/ice feedback. Results indicated that the total deposition BC and organic matter (OM) in snow/ice in the monsoon season (May–September) were much more than non-monsoon season (the remainder of the year). The great BC and OM deposition were simulated along the margin of the TP in the non-monsoon season, and the higher deposition values also occurred in the western TP than the other regions during the monsoon period. BC-in-snow/ice decreased surface albedo and caused positive surface radiative forcing (SRF) (3.0–4.5 W m-2 ) over the western TP in the monsoon season. The maximum SRF (5–6 W m-2 ) simulated in the Himalayas and southeastern TP in the non-monsoon season. The surface temperature increased by 0.1–1.5 °C and snow water equivalent decreased by 5–25 mm over the TP, which showed similar spatial distributions with the variations of SRF in each season. This study provided a useful tool to investigate the mechanisms involved in the effect of aerosols on climate change and the water cycle in the cryospheric environment of the TP.

Abstract

We quantified the impacts of variations in meteorological parameters and emissions on decadal, interannual, and seasonal variations of atmospheric black carbon (BC) in the Tibetan Plateau for 1980–2010 using a global 3-dimensional chemical transport model driven by the Modern Era Retrospective-analysis for Research and Applications (MERRA) meteorological fields. From 1980 to 2010, simulated surface BC concentrations and all-sky direct radiative forcing at the top of the atmosphere due to atmospheric BC increased by 0.15 μg m−3 (63%) and by 0.23 W m−2 (62%), respectively, averaged over the Tibetan Plateau (75–105°E, 25–40°N). Simulated annual mean surface BC concentrations were in the range of 0.24–0.40 μg m−3 averaged over the plateau for 1980–2010, with the decadal trends of 0.13 μg m−3 per decade in the 1980s and 0.08 in the 2000s. The interannual variations were −5.4% to 7.0% for deviation from the mean, 0.0062 μg m−3 for mean absolute deviation, and 2.5% for absolute percent departure from the mean. Model sensitivity simulations indicated that the decadal trends of surface BC concentrations were mainly driven by changes in emissions, while the interannual variations were dependent on variations of both meteorological parameters and emissions. Meteorological parameters played a crucial role in driving the interannual variations of BC especially in the monsoon season.

Abstract

Black carbon (BC) deposited on snow and glacier surfaces can reduce albedo and lead to accelerated melt. An ice core recovered from Guoqu glacier on Mt. Geladaindong and analyzed using a Single Particle Soot Photometer (SP2) provides the first long-term (1843–1982) record of BC from the central Tibetan Plateau. Post 1940 the record is characterized by an increased occurrence of years with above average BC, and the highest BC values of the record. The BC increase in recent decades is likely caused by a combination of increased emissions from regional BC sources, and a reduction in snow accumulation. Guoqu glacier has received no net ice accumulation since the 1980s, and is a potential example of a glacier where an increase in the equilibrium line altitude is exposing buried high impurity layers. That BC concentrations in the uppermost layers of the Geladaindong ice core are not substantially higher relative to deeper in the ice core suggests that some of the BC that must have been deposited on Guoqu glacier via wet or dry deposition between 1983 and 2005 has been removed from the surface of the glacier, potentially via supraglacial or englacial meltwater.

Abstract

Recently, the light-absorbing organic carbon, i.e., brown carbon (BrC), has received an increasing attention, because they could significantly absorb the solar radiation in the range of short wavelengths rather than the purely scattering effect. BrC is ubiquitous in the troposphere. It could undergo long range transport within the atmospheric circulation. After the deposition on the surface of snow or ice in the cryospheric region, as the major light absorbing impurities with black carbon and dust, BrC could reduce the snow albedo and accelerate the glacier melting. In this context, this paper summarized the current knowledge of BrC (in aerosols and snow) in the cryospheric regions including the Arctic, Antarctic, and Alpines. Although some works have been conducted in those region, the current dataset on the optical properties of BrC like Absorption Ångström Exponent (AAE ) and Mass Absorption Efficiency (MAE ) is still limited, which hampers stimulating an accurate evaluation of its climate effects. Especially in the Himalayas and Tibetan Plateau, where very limited information concerning BrC is available. Considering biomass burning as a dominant source of BrC, a large amount of emissions from biomass burning in South Asia could reach the Himalayas and Tibetan Plateau, where the climate effect of BrC merits more investigation in the future.

Abstract

This study aims to quantify the impact of black carbon from inland shipping on air quality, expressed as elemental carbon (EC) near inland waterways in The Netherlands. Downwind measurements of particle numbers and EC were used to establish emission factors for EC from inland shipping using inverse modelling. These emission factors were combined with data on energy consumption to derive annual average emissions rates for all Dutch waterways. A line source model was applied to compute the contribution of inland shipping to annual average EC concentrations for around 140,000 people living within 200m of busy waterways in The Netherlands. The results showed that they are exposed to additional EC concentrations of up to 0.5μgEC per m3 depending on the shipping volume and distance from the waterway. In view of the envisaged growth in water transport, this underlines the need to reduce combustion emissions from inland shipping. Targeting "gross" polluters may be the most effective approach since 30% of ships cause more than 80% of the total emissions. © 2014 Elsevier Ltd.

Abstract

Black carbon (BC) aerosols can strongly absorb solar radiation in very broad spectral wavebands, from the visible to the infrared. As a potential factor contributing to global warming, BC aerosols not only directly change the radiation balance of the earth-atmosphere system, but also indirectly affect global or regional climate by acting as cloud condensation nuclei or ice nuclei to alter cloud microphysical properties. Here, recent progresses in the studies of radiative forcing due to BC and its climate effects are reviewed. The uncertainties in current researches are discussed and some suggestions are provided for future investigations. Zhang, H., and Z. Wang, 2011: Advances in the study of black carbon effects on climate. Adv. Clim. Change Res., 2 (1), doi: 10.3724/SP.J.1248.2011.00023.

Abstract

Black carbon (BC) aerosol, accounting for a minor fraction of atmospheric aerosols, is attracting increased attention due to its impact on air quality, human health, and climate change. Focusing on BC emission reduction, this paper gives a brief introduction to the sources and global distribution of BC. Along with the decrease of BC emissions from such actions as the reduction of global greenhouse gases (GHGs) and regulating local air quality, it also highlights other BC reduction approaches such as control and improvement of combustion conditions, the elimination of open biomass burning, and the sequestration of BC by biomass pyrolysis. Finally, it is stressed that at this moment there is no enough reason to push BC reduction into any climate change related negotiations, although BC has been included in some of so-called win-win reduction targets for the quick response to both climate and non-climate appeals. Zhi, G., X. Zhang, H. Cheng, et al., 2011: Practical paths towards lowering black carbon emissions. Adv. Clim. Change Res., 2 (1), doi: 10.3724/SP.J.1248.2011.00012.