Present‐day springtime high‐latitude surface albedo as a predictor of simulated climate sensitivity

Levis, Samuel; Bonan, Gordon B.; Lawrence, P.

doi:10.1029/2007gl030775

Cited by 22 publications

(12 citation statements)

References 21 publications

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“…In addition, the SAT response found here may be relatively low, since models that underestimate the present-day snow cover, such as the CCSM, also underestimate the climate sensitivity to snow cover change (Levis et al 2007). 6.…”

Section: Discussionmentioning

confidence: 86%

The Atmospheric Response to Projected Terrestrial Snow Changes in the Late Twenty-First Century

et al. 2010

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Two atmospheric general circulation model experiments are conducted with specified terrestrial snow conditions representative of 1980-99 and 2080-99. The snow states are obtained from twentieth-century and twenty-first-century coupled climate model integrations under increasing greenhouse gas concentrations. Sea surface temperatures, sea ice, and greenhouse gas concentrations are set to 1980-99 values in both atmospheric model experiments to isolate the effect of the snow changes. The reduction in snow cover in the twenty-first century relative to the twentieth century increases the solar radiation absorbed by the surface, and it enhances the upward longwave radiation and latent and sensible fluxes that warm the overlying atmosphere. The maximum twenty-first-century minus twentieth-century surface air temperature (SAT) differences are relatively small (,38C) compared with those due to Arctic sea ice changes (;108C). However, they are continental in scale and are largest in fall and spring, when they make a significant contribution to the overall warming over Eurasia and North America in the twenty-first century. The circulation response to the snow changes, while of modest amplitude, involves multiple components, including a local low-level trough, remote Rossby wave trains, an annular pattern that is strongest in the stratosphere, and a hemispheric increase in geopotential height.

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Section: Discussionmentioning

confidence: 86%

The Atmospheric Response to Projected Terrestrial Snow Changes in the Late Twenty-First Century

et al. 2010

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“…The remarkable albedo difference between snow covered and snow‐free surfaces may have a large climatic impact, known as snow (ice) albedo feedback. The development of more accurate snow and albedo parameterizations should improve model estimates of climate sensitivity to albedo changes [ Levis et al , 2007]. Although snow albedo is one of the most important parameters in climate studies, in many GCMs, it is parameterized empirically [e.g., Pedersen and Winther , 2005; Brun et al , 2008].…”

Section: Introductionmentioning

confidence: 99%

Physically based snow albedo model for calculating broadband albedos and the solar heating profile in snowpack for general circulation models

et al. 2011

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[1] A physically based snow albedo model (PBSAM), which can be used in a general circulation model, is developed. PBSAM calculates broadband albedos and the solar heating profile in snowpack as functions of snow grain size and concentrations of snow impurities, black carbon and mineral dust, in snow with any layer structure and under any solar illumination condition. The model calculates the visible and near-infrared (NIR) albedos by dividing each broadband spectrum into several spectral subbands to simulate the change in spectral distribution of solar radiation in the broadband spectra at the snow surface and in the snowpack. PBSAM uses (1) the look-up table method for calculations of albedo and transmittance in spectral subbands for a homogeneous snow layer, (2) an "adding" method for calculating the effect of an inhomogeneous snow structure on albedo and transmittance, and (3) spectral weighting of radiative parameters to obtain the broadband values from the subbands. We confirmed that PBSAM can calculate the broadband albedos of single-and two-layer snow models with good accuracy by comparing them with those calculated by a spectrally detailed radiative transfer model (RTM). In addition, we used radiation budget measurements and snow pit data obtained during the two winters from 2007 to 2009 at Sapporo, Hokkaido, Japan, for simulation of the broadband albedos by PBSAM and compared the results with the in situ measurements. A five-layer snow model with one visible subband and three NIR subbands were necessary for accurate simulation. Comparison of solar heating profiles calculated by PBSAM with those calculated by the spectrally detailed RTM showed that PBSAM calculated accurate solar heating profiles when at least three subbands were used in both the visible and NIR bands.Citation: Aoki, T., K. Kuchiki, M. Niwano, Y. Kodama, M. Hosaka, and T. Tanaka (2011), Physically based snow albedo model for calculating broadband albedos and the solar heating profile in snowpack for general circulation models, J. Geophys.

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“…Understanding controls of snow cover evolution is important because 1) cryospheric response to climate forcing largely determines climate sensitivity (e.g., Lemke et al, 2007;Levis et al, 2007), and 2) most of the interannual variability in mid-and high-latitude planetary albedo is caused by changes in snow and sea-ice cover (Qu and Hall, 2005). Atmospheric particles have short lifetimes, but influence the snowpack energy budget via several mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Springtime warming and reduced snow cover from carbonaceous particles

et al. 2009

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Abstract. Boreal spring climate is uniquely susceptible to solar warming mechanisms because it has expansive snow cover and receives relatively strong insolation. Carbonaceous particles can influence snow coverage by warming the atmosphere, reducing surface-incident solar energy (dimming), and reducing snow reflectance after deposition (darkening). We apply a range of models and observations to explore impacts of these processes on springtime climate, drawing several conclusions: 1) Nearly all atmospheric particles (those with visible-band single-scatter albedo less than 0.999), including all mixtures of black carbon (BC) and organic matter (OM), increase net solar heating of the atmosphere-snow column. 2) Darkening caused by small concentrations of particles within snow exceeds the loss of absorbed energy from concurrent dimming, thus increasing solar heating of snowpack as well (positive net surface forcing). Over global snow, we estimate 6-fold greater surface forcing from darkening than dimming, caused by BC+OM. 3) Equilibrium climate experiments suggest that fossil fuel and biofuel emissions of BC+OM induce 95% as much springtime snow cover loss over Eurasia as anthropogenic carbon dioxide, a consequence of strong snowalbedo feedback and large BC+OM emissions from Asia. 4) Of 22 climate models contributing to the IPCC Fourth Assessment Report, 21 underpredict the rapid warming (0.64 • C decade −1 ) observed over springtime Eurasia since 1979. Darkening from natural and anthropogenic sources of BC and mineral dust exerts 3-fold greater forcing on springCorrespondence to: M. G. Flanner (mflanner@ucar.edu) time snow over Eurasia (3.9 W m −2 ) than North America (1.2 W m −2 ). Inclusion of this forcing significantly improves simulated continental warming trends, but does not reconcile the low bias in rate of Eurasian spring snow cover decline exhibited by all models, likely because BC deposition trends are negative or near-neutral over much of Eurasia. Improved Eurasian warming may therefore relate more to darkeninginduced reduction in mean snow cover.

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Present‐day springtime high‐latitude surface albedo as a predictor of simulated climate sensitivity

Cited by 22 publications

References 21 publications

The Atmospheric Response to Projected Terrestrial Snow Changes in the Late Twenty-First Century

The Atmospheric Response to Projected Terrestrial Snow Changes in the Late Twenty-First Century

Physically based snow albedo model for calculating broadband albedos and the solar heating profile in snowpack for general circulation models

Springtime warming and reduced snow cover from carbonaceous particles

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