Abstract
Abstract. A new physically based parameterisation of black carbon (BC) in snow was developed and implemented in the Canadian Atmospheric Global Climate Model (CanAM4.2). Simulated BC snow mixing ratios and BC snow radiative forcings are in good agreement with measurements and results from other models. Simulations with the improved model yield considerable trends in regional BC concentrations in snow and BC snow radiative forcings during the time period from 1950–1959 to 2000–2009. Increases in radiative forcings for Asia and decreases for Europe and North America are found to be associated with changes in BC emissions. Additional sensitivity simulations were performed in order to study the impact of BC emission changes between 1950–1959 and 2000–2009 on surface albedo, snow cover fraction, and surface air temperature. Results from these simulations indicate that impacts of BC emission changes on snow albedos between these 2 decades are small and not significant. Overall, changes in BC concentrations in snow have much smaller impacts on the cryosphere than the net warming surface air temperatures during the second half of the 20th century.
Highlights
Snow plays an important role in the land surface radiation budget and climate
Snow albedo can be strongly reduced by absorbing aerosols such as black carbon (BC), brown organic carbon, or dust which have been deposited on the snow through dry and wet deposition and cause warming of the snowpack (Warren and Wiscombe, 1980, 1985; Hansen and Nazarenko, 2004; Hadley and Kirchstetter, 2012)
The modelling approach accounts for snow metamorphism and BC concentration in snow, which affect snow albedo
Summary
Snow plays an important role in the land surface radiation budget and climate. These albedo change estimates were used to calculate the radiative forcing (RF) and climate response. In a recent study of Jiao et al (2014), BC deposition fields from 25 global aerosol models were used to investigate effects of BC transport and deposition processes on BC concentration in snow. Flanner et al (2009) concluded that fossil fuel and biofuel emissions of BC induce a large springtime snow cover loss over Eurasia as a consequence of strong snow-albedo feedbacks and large BC emissions from Asia, with a magnitude similar to impacts of anthropogenic carbon dioxide concentrations on SCE.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
