scholarly journals Light-Absorbing Impurities on Urumqi Glacier No.1 in Eastern Tien Shan: Concentrations and Implications for Radiative Forcing Estimates During the Ablation Period

2021 ◽  
Vol 9 ◽  
Author(s):  
Xin Zhang ◽  
Zhongqin Li ◽  
Xiaoni You ◽  
Yuanyang She ◽  
Mengyuan Song ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Tien Shan ◽  
Snow Melting ◽  
Glacier Surface ◽  
Lower Altitude ◽  
The Past ◽  
Surface Snow ◽  
Fresh Snow ◽  
Aerosol Radiative ◽  
Snow Samples

Light-absorbing impurities (LAIs) in surface snow and snow pits together with LAIs’ concentrations and their impacts on albedo reduction and sequent radiative forcing (RF) have been investigated in the past. Here, we focused on temporal–spatial distributions of LAIs, especially on the albedo reduction and radiative forcing caused by the LAIs in Urumqi Glacier No.1. Various snow samples, including fresh snow, aged snow, and granular ice were collected between 3,770 and 4,105 m a.s.l of Urumqi Glacier No.1 during the snowmelt season of 2015. For the surface snow samples, BC and OC concentrations were 582 and 1,590 ng g−1, respectively. Mineral dust (MD) concentrations were 110 μg g−1. Due to the different ablation status of the glacier surface, LAIs accumulate at the lower altitude of the glacier. The estimation by the Snow, Ice, and Aerosol Radiative (SNICAR) model indicated that BC and MD could reduce the albedo by 12.8 and 10.3% in fresh snow, aged snow by 23.3 and 5.9%, and granular ice by 22.4 and 26.7%, respectively. The RF of MD was higher than that of BC in fresh snow and granular ice, whereas the RF of BC exceeded MD in aged snow. These findings suggested that BC was the main forcing factor in snow melting and dust was the main forcing factor in accelerating glacier melt.

scholarly journals Characteristics of ionic concentration and δ18O and their variability in dry-season and wet-season snow on Ürümqi glacier No. 1, eastern Tien Shan, central Asia

2008 ◽  
Vol 49 ◽  
pp. 217-223 ◽  
Author(s):  
Zhongqin Li ◽  
Wenbin Wang ◽  
Feiteng Wang ◽  
Huilin Li ◽  
Mingjun Zhang
Keyword(s):  
Central Asia ◽  
Ionic Concentration ◽  
Tien Shan ◽  
Wet Season ◽  
Snow Chemistry ◽  
Ionic Concentrations ◽  
Depositional Processes ◽  
Surface Snow ◽  
Dry Seasons ◽  
Snow Samples

AbstractTo investigate the environmental and climatic significance of the ice-core records from the Tien Shan, central Asia, the characteristics of ionic concentration and oxygen isotopic ratio (δ18O) as well as their variability are assessed from surface-snow samples as well as old-snow samples collected year-round at weekly intervals from November 2002 to October 2005 on Ürümqi glacier No. 1, eastern Tien Shan. The results indicate that the δ18O in surface-snow samples is reversely coincident with air temperature and insignificantly affected by post-depositional processes. Ionic concentrations in the wet-season (1 November to 31 March) snow are overall higher than those in dry-season (1 April to 31 October) snow, while the variability of relative ionic composition between dry seasons is slightly less than that between wet seasons. During dry seasons, surface-snow chemistry was mostly controlled by the chemical content entrained in some sporadic precipitations. When precipitation is absent, the effect of all post-depositional processes together elevated the ionic concentrations in surface snow. During wet seasons, the snow chemistry is determined mainly by the input of aerosols entrained in precipitation and the elution process from percolation of meltwater.

scholarly journals Bounding global aerosol radiative forcing of climate change

2020 ◽  
Author(s):  
Nicolas Bellouin ◽  
Keyword(s):  
Radiative Forcing ◽  
Review Paper ◽  
Aerosol Radiative Forcing ◽  
The Past ◽  
Open Questions ◽  
Substantial Progress ◽  
Theoretical Considerations ◽  
Present Understanding ◽  
Lines Of Evidence ◽  
Aerosol Radiative

<p>Aerosol radiative forcing plays an important role in the attribution of past climate changes, estimates of future allowable carbon emissions, and the assessment of potential geoengineering solutions. Substantial progress made over the past 40 years in observing, understanding, and modelling aerosol processes helped quantify aerosol radiative forcing, but uncertainties remain large.</p><p>In spring 2018, under the auspices of the World Climate Research Programme's Grand Science Challenge on Clouds, Circulation and Climate Sensitivity, thirty-six experts gathered to take a fresh and comprehensive look at present understanding of aerosol radiative forcing and identify prospects for progress on some of the most pressing open questions. The outcome of that meeting is a review paper, Bellouin et al. (2019), accepted for publication in Reviews of Geophysics. This review provides a new range of aerosol radiative forcing over the industrial era based on multiple, traceable and arguable lines of evidence, including modelling approaches, theoretical considerations, and observations. A substantial achievement is to focus on lines of evidence rather than a survey of past results or expert judgement, and to make the open questions much more specific.</p><p>This talk will present the key messages and arguments of the review and identify work that show promise for improving the quantification of aerosol radiative forcing.</p>

scholarly journals Aerosol radiative forcings induced by substantial changes in anthropogenic emissions in China from 2008 to 2016

2021 ◽  
Vol 21 (8) ◽  
pp. 5965-5982
Author(s):  
Mingxu Liu ◽  
Hitoshi Matsui
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Radiative Forcing ◽  
Eastern China ◽  
Radiation Budget ◽  
Anthropogenic Emissions ◽  
Radiative Forcings ◽  
The Past ◽  
Positive Direct ◽  
Aerosol Radiative

Abstract. Anthropogenic emissions in China play an important role in altering the global radiation budget. Over the past decade, the strong clean-air policies in China have resulted in substantial reductions of anthropogenic emissions of sulfur dioxide (SO2) and primary particulate matter, and air quality in China has consequently improved. However, the resultant aerosol radiative forcings have been poorly understood. In this study, we used an advanced global climate model integrated with the latest localized emission inventory to quantify the aerosol radiative forcings by the changes of anthropogenic emissions in China between 2008 and 2016. By comparing with multiple observation datasets, our simulations reproduced the considerable reductions of sulfate and black carbon (BC) mass loadings reasonably well over eastern China (the key region subject to stringent emission controls) during the period and accordingly showed a clear decline in both aerosol optical depth and absorption aerosol optical depth. The results revealed a regional annual mean positive direct radiative forcing (DRF) of +0.29 W m−2 at the top of the atmosphere (TOA) due to the reduction of SO2 emissions. This positive aerosol radiative forcing was comprised of diminished sulfate scattering (+0.58 W m−2), enhanced nitrate radiative effects (−0.29 W m−2), and could be completely offset by the concurrent reduction of BC emissions that induced a negative BC DRF of −0.33 W m−2. Despite the small net aerosol DRF (−0.05 W m−2) at the TOA, aerosol–radiation interactions could explain the surface brightening in China over the past decade. The overall reductions in aerosol burdens and associated optical effects mainly from BC and sulfate enhanced the regional annual mean downward solar radiation flux at the surface by +1.0 W m−2 between 2008 and 2016. The enhancement was in general agreement with a long-term observational record of surface energy fluxes in China. We also estimated that aerosol effects on cloud radiative forcings may have played a dominant role in the net aerosol radiative forcings at the TOA in China and over the northern Pacific Ocean during the study period. This study will facilitate more informed assessment of climate responses to projected emissions in the future as well as to sudden changes in human activities (e.g., the COVID-19 lockdown).

scholarly journals Retention and radiative forcing of black carbon in eastern Sierra Nevada snow

2013 ◽  
Vol 7 (1) ◽  
pp. 365-374 ◽  
Author(s):  
K. M. Sterle ◽  
J. R. McConnell ◽  
J. Dozier ◽  
R. Edwards ◽  
M. G. Flanner
Keyword(s):  
Black Carbon ◽  
Sierra Nevada ◽  
Radiative Forcing ◽  
Major Ions ◽  
Snow Accumulation ◽  
Radiation Balance ◽  
Surface Snow ◽  
Dust Surface ◽  
Snow Samples ◽  
Eastern Sierra Nevada

Abstract. When contaminated by absorbing particles, such as refractory black carbon (rBC) and continental dust, snow's albedo decreases and thus its absorption of solar radiation increases, thereby hastening snowmelt. For this reason, an understanding of rBC's affect on snow albedo, melt processes, and radiation balance is critical for water management, especially in a changing climate. Measurements of rBC in a sequence of snow pits and surface snow samples in the eastern Sierra Nevada of California during the snow accumulation and ablation seasons of 2009 show that concentrations of rBC were enhanced sevenfold in surface snow (~25 ng g–1) compared to bulk values in the snowpack (~3 ng g–1). Unlike major ions, which were preferentially released during the initial melt, rBC and continental dust were retained in the snow, enhancing concentrations well into late spring, until a final flush occurred during the ablation period. We estimate a combined rBC and continental dust surface radiative forcing of 20 to 40 W m−2 during April and May, with dust likely contributing a greater share of the forcing.

scholarly journals Observations and model simulations of snow albedo reduction in seasonal snow due to insoluble light-absorbing particles during 2014 Chinese survey

2017 ◽  
Vol 17 (3) ◽  
pp. 2279-2296 ◽  
Author(s):  
Xin Wang ◽  
Wei Pu ◽  
Yong Ren ◽  
Xuelei Zhang ◽  
Xueying Zhang ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Northeastern China ◽  
Transfer Model ◽  
Snow Albedo ◽  
Hexagonal Plate ◽  
Mixing Ratios ◽  
Seasonal Snow ◽  
Surface Snow ◽  
Fresh Snow ◽  
Snow Samples

Abstract. A snow survey was carried out to collect 13 surface snow samples (10 for fresh snow, and 3 for aged snow) and 79 subsurface snow samples in seasonal snow at 13 sites across northeastern China in January 2014. A spectrophotometer combined with chemical analysis was used to quantify snow particulate absorption by insoluble light-absorbing particles (ILAPs, e.g., black carbon, BC; mineral dust, MD; and organic carbon, OC) in snow. Snow albedo was measured using a field spectroradiometer. A new radiative transfer model (Spectral Albedo Model for Dirty Snow, or SAMDS) was then developed to simulate the spectral albedo of snow based on the asymptotic radiative transfer theory. A comparison between SAMDS and an existing model – the Snow, Ice, and Aerosol Radiation (SNICAR) – indicates good agreements in the model-simulated spectral albedos of pure snow. However, the SNICAR model values tended to be slightly lower than those of SAMDS when BC and MD were considered. Given the measured BC, MD, and OC mixing ratios of 100–5000, 2000–6000, and 1000–30 000 ng g−1, respectively, in surface snow across northeastern China, the SAMDS model produced a snow albedo in the range of 0.95–0.75 for fresh snow at 550 nm, with a snow grain optical effective radius (Reff) of 100 µm. The snow albedo reduction due to spherical snow grains assumed to be aged snow is larger than fresh snow such as fractal snow grains and hexagonal plate or column snow grains associated with the increased BC in snow. For typical BC mixing ratios of 100 ng g−1 in remote areas and 3000 ng g−1 in heavy industrial areas across northern China, the snow albedo for internal mixing of BC and snow is lower by 0.005 and 0.036 than that of external mixing for hexagonal plate or column snow grains with Reff of 100 µm. These results also show that the simulated snow albedos by both SAMDS and SNICAR agree well with the observed values at low ILAP mixing ratios but tend to be higher than surface observations at high ILAP mixing ratios.

scholarly journals An empirical model of global climate – Part 2: Implications for future temperature

2012 ◽  
Vol 12 (9) ◽  
pp. 23913-23974 ◽  
Author(s):  
N. R. Mascioli ◽  
T. Canty ◽  
R. J. Salawitch
Keyword(s):  
Surface Temperature ◽  
Climate Sensitivity ◽  
Radiative Forcing ◽  
Global Climate ◽  
Climate Feedback ◽  
Anthropogenic Aerosol ◽  
Aerosol Radiative Forcing ◽  
The Past ◽  
Global Surface ◽  
Aerosol Radiative

Abstract. IPCC (2007) has shown that atmosphere-ocean general circulation models (GCMs) from various research centers simulate the rise in global mean surface temperature over the past century rather well, yet provide divergent estimates of temperature for the upcoming decades. We use an empirical model of global climate based on a multiple linear regression (MLR) analysis of the past global surface temperature anomalies (ΔT) to explore why GCMs might provide divergent estimates of future temperature. Our focus is on the interplay of three factors: net anthropogenic aerosol radiative forcing (NAA RF), climate feedback (water vapor, clouds, surface albedo) in response to greenhouse gas radiative forcing (GHG RF), and ocean heat export (OHE). Our model is predicated on two key assumptions: whatever climate feedback is needed to account for past temperature rise will persist into the future and whatever fraction of anthropogenic RF (GHG RF + NAA RF) is exported to the oceans to match the observed rise in ocean heat content will also persist. Even with these assumptions, modeled future ΔT mimics the behavior of GCMs because the ~110 record of global surface temperature can not distinguish between two possibilities. If anthropogenic aerosols presently exert small cooling on global climate, feedback must be weak and the future rise in global average surface temperature in 2053, the time CO2 is projected to double according to RCP 8.5, could be moderate. If aerosols presently exert large cooling of global climate, feedback must be large and future ΔT when CO2 doubles could be substantial. Reduced uncertainty for climate projection requires observationally based constraints that can narrow the uncertainties that presently exist for net anthropogenic aerosol radiative forcing as well as the totality of feedbacks that occur in response to a GHG RF perturbation. GCMs are often compared by evaluating the equilibrium response to a doubling of CO2, termed climate sensitivity. In our model framework, ΔT at the time CO2 doubles is nearly independent of OHE, because climate feedback must be adjusted to properly simulate observed temperature. Our simulations show that if a small fraction of anthropogenic RF is exported to the ocean, equilibrium climate sensitivity closely represents the modeled ΔT at the time CO2 doubles. Conversely, if this fraction is large, ΔT when CO2 doubles is much less than the equilibrium climate sensitivity (i.e. the model is now far from equilibrium). Similar behavior likely occurs within GCMs. We therefore suggest the dependence of climate sensitivity on OHE be factored into analyses that use this metric to compare and evaluate GCMs.

scholarly journals Depositional characteristics of NH4+ on Ürümqi glacier No. 1, eastern Tien Shan, China

2008 ◽  
Vol 49 ◽  
pp. 161-165 ◽  
Author(s):  
Li Huilin ◽  
Li Zhongqin ◽  
Wang Wenbin ◽  
Wang Feiteng
Keyword(s):  
Seasonal Variations ◽  
Chemical Species ◽  
Meteorological Factor ◽  
Tien Shan ◽  
Weekly Basis ◽  
Depositional Processes ◽  
Surface Snow ◽  
Wet Condition ◽  
Autumn And Winter ◽  
Snow Samples

AbstractInvestigation into the depositional and post-depositional processes of atmospheric NH4+ on Ürümqi glacier No. 1 (UG1), China, was implemented within the Program for Glacier Processes Investigation (PGPI) campaign. Aerosol and surface snow samples were collected concurrently on a weekly basis from March 2004 to March 2005 in the UG1 accumulation zone at the headwaters of the Ürümqi river, eastern Tien Shan. All samples were analyzed for NH4+ and other chemical species. This paper investigates the seasonal variations of NH4+. A significant linear relationship (R2 = 0.70, N = 21, P < 0.01) between NH4+ concentrations in surface snow and aerosol was found during spring and summer, indicating that the warm–wet condition facilitates the air–snow exchange of NH4+. Humidity was found to be a significant meteorological factor influencing NH4+ in deposition in autumn and winter. The NH4+ concentration in aerosol clearly shows a trend similar to that in surface snow, suggesting that the variation of atmospheric NH4+ might have been preserved in the surface snow. The possible source of NH4+ is discussed in this paper.

Methods for extraction of microorganism DNA from glacier surface snow

2012 ◽  
Vol 4 (6) ◽  
pp. 484
Author(s):  
Yan Pei-Ying ◽  
Hou Shu-Gui ◽  
Chen Tuo ◽  
Zhang Shu-Hong ◽  
Sun Wei-Jun
Keyword(s):  
Glacier Surface ◽  
Surface Snow

scholarly journals Improved estimates of preindustrial biomass burning reduce the magnitude of aerosol climate forcing in the Southern Hemisphere

2021 ◽  
Vol 7 (22) ◽  
pp. eabc1379
Author(s):  
Pengfei Liu ◽  
Jed O. Kaplan ◽  
Loretta J. Mickley ◽  
Yang Li ◽  
Nathan J. Chellman ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Radiative Forcing ◽  
Ice Core ◽  
Ice Cores ◽  
Terrestrial Ecosystems ◽  
Rapid Expansion ◽  
Past Century ◽  
Fire Emissions ◽  
The Past ◽  
Fire Activity

Fire plays a pivotal role in shaping terrestrial ecosystems and the chemical composition of the atmosphere and thus influences Earth’s climate. The trend and magnitude of fire activity over the past few centuries are controversial, which hinders understanding of preindustrial to present-day aerosol radiative forcing. Here, we present evidence from records of 14 Antarctic ice cores and 1 central Andean ice core, suggesting that historical fire activity in the Southern Hemisphere (SH) exceeded present-day levels. To understand this observation, we use a global fire model to show that overall SH fire emissions could have declined by 30% over the 20th century, possibly because of the rapid expansion of land use for agriculture and animal production in middle to high latitudes. Radiative forcing calculations suggest that the decreasing trend in SH fire emissions over the past century largely compensates for the cooling effect of increasing aerosols from fossil fuel and biofuel sources.

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