Present-day climate forcing and response from black carbon in snow
We apply our Snow, Ice, and Aerosol Radiative (SNICAR) model, coupled to a general circulation model with prognostic carbon aerosol transport, to improve understanding of climate forcing and response from black carbon (BC) in snow. Building on two previous studies, we account for interannually varyi...
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Language: | English |
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American Geophysical Union
2007
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Online Access: | http://nldr.library.ucar.edu/repository/collections/OSGC-000-000-003-945 https://doi.org/10.1029/2006JD008003 |
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ftncar:oai:drupal-site.org:articles_6647 2023-07-30T04:06:48+02:00 Present-day climate forcing and response from black carbon in snow Flanner, Mark (author) Zender, Charles (author) Randerson, James (author) Rasch, Philip (author) 2007-06-05 application/pdf http://nldr.library.ucar.edu/repository/collections/OSGC-000-000-003-945 https://doi.org/10.1029/2006JD008003 en eng American Geophysical Union Journal of Geophysical Research-Atmospheres http://nldr.library.ucar.edu/repository/collections/OSGC-000-000-003-945 doi:10.1029/2006JD008003 ark:/85065/d7jh3md7 Copyright 2007 American Geophysical Union. Text article 2007 ftncar https://doi.org/10.1029/2006JD008003 2023-07-17T18:36:43Z We apply our Snow, Ice, and Aerosol Radiative (SNICAR) model, coupled to a general circulation model with prognostic carbon aerosol transport, to improve understanding of climate forcing and response from black carbon (BC) in snow. Building on two previous studies, we account for interannually varying biomass burning BC emissions, snow aging, and aerosol scavenging by snow meltwater. We assess uncertainty in forcing estimates from these factors, as well as BC optical properties and snow cover fraction. BC emissions are the largest source of uncertainty, followed by snow aging. The rate of snow aging determines snowpack effective radius (r e), which directly controls snow reflectance and the magnitude of albedo change caused by BC. For a reasonable r e range, reflectance reduction from BC varies threefold. Inefficient meltwater scavenging keeps hydrophobic impurities near the surface during melt and enhances forcing. Applying biomass burning BC emission inventories for a strong (1998) and weak (2001) boreal fire year, we estimate global annual mean BC/snow surface radiative forcing from all sources (fossil fuel, biofuel, and biomass burning) of +0.054 (0.007--0.13) and +0.049 (0.007–0.12) W m⁻², respectively. Snow forcing from only fossil fuel + biofuel sources is +0.043 W m⁻² (forcing from only fossil fuels is +0.033 W m⁻²), suggesting that the anthropogenic contribution to total forcing is at least 80%. The 1998 global land and sea-ice snowpack absorbed 0.60 and 0.23 W m⁻², respectively, because of direct BC/snow forcing. The forcing is maximum coincidentally with snowmelt onset, triggering strong snow-albedo feedback in local springtime. Consequently, the "efficacy" of BC/snow forcing is more than three times greater than forcing by CO₂. The 1998 and 2001 land snowmelt rates north of 50°N are 28% and 19% greater in the month preceding maximum melt of control simulations without BC in snow. With climate feedbacks, global annual mean 2-meter air temperature warms 0.15 and ... Article in Journal/Newspaper Sea ice OpenSky (NCAR/UCAR - National Center for Atmospheric Research/University Corporation for Atmospheric Research) Journal of Geophysical Research 112 D11 |
institution |
Open Polar |
collection |
OpenSky (NCAR/UCAR - National Center for Atmospheric Research/University Corporation for Atmospheric Research) |
op_collection_id |
ftncar |
language |
English |
description |
We apply our Snow, Ice, and Aerosol Radiative (SNICAR) model, coupled to a general circulation model with prognostic carbon aerosol transport, to improve understanding of climate forcing and response from black carbon (BC) in snow. Building on two previous studies, we account for interannually varying biomass burning BC emissions, snow aging, and aerosol scavenging by snow meltwater. We assess uncertainty in forcing estimates from these factors, as well as BC optical properties and snow cover fraction. BC emissions are the largest source of uncertainty, followed by snow aging. The rate of snow aging determines snowpack effective radius (r e), which directly controls snow reflectance and the magnitude of albedo change caused by BC. For a reasonable r e range, reflectance reduction from BC varies threefold. Inefficient meltwater scavenging keeps hydrophobic impurities near the surface during melt and enhances forcing. Applying biomass burning BC emission inventories for a strong (1998) and weak (2001) boreal fire year, we estimate global annual mean BC/snow surface radiative forcing from all sources (fossil fuel, biofuel, and biomass burning) of +0.054 (0.007--0.13) and +0.049 (0.007–0.12) W m⁻², respectively. Snow forcing from only fossil fuel + biofuel sources is +0.043 W m⁻² (forcing from only fossil fuels is +0.033 W m⁻²), suggesting that the anthropogenic contribution to total forcing is at least 80%. The 1998 global land and sea-ice snowpack absorbed 0.60 and 0.23 W m⁻², respectively, because of direct BC/snow forcing. The forcing is maximum coincidentally with snowmelt onset, triggering strong snow-albedo feedback in local springtime. Consequently, the "efficacy" of BC/snow forcing is more than three times greater than forcing by CO₂. The 1998 and 2001 land snowmelt rates north of 50°N are 28% and 19% greater in the month preceding maximum melt of control simulations without BC in snow. With climate feedbacks, global annual mean 2-meter air temperature warms 0.15 and ... |
author2 |
Flanner, Mark (author) Zender, Charles (author) Randerson, James (author) Rasch, Philip (author) |
format |
Article in Journal/Newspaper |
title |
Present-day climate forcing and response from black carbon in snow |
spellingShingle |
Present-day climate forcing and response from black carbon in snow |
title_short |
Present-day climate forcing and response from black carbon in snow |
title_full |
Present-day climate forcing and response from black carbon in snow |
title_fullStr |
Present-day climate forcing and response from black carbon in snow |
title_full_unstemmed |
Present-day climate forcing and response from black carbon in snow |
title_sort |
present-day climate forcing and response from black carbon in snow |
publisher |
American Geophysical Union |
publishDate |
2007 |
url |
http://nldr.library.ucar.edu/repository/collections/OSGC-000-000-003-945 https://doi.org/10.1029/2006JD008003 |
genre |
Sea ice |
genre_facet |
Sea ice |
op_relation |
Journal of Geophysical Research-Atmospheres http://nldr.library.ucar.edu/repository/collections/OSGC-000-000-003-945 doi:10.1029/2006JD008003 ark:/85065/d7jh3md7 |
op_rights |
Copyright 2007 American Geophysical Union. |
op_doi |
https://doi.org/10.1029/2006JD008003 |
container_title |
Journal of Geophysical Research |
container_volume |
112 |
container_issue |
D11 |
_version_ |
1772819704950292480 |