The impact of atmospheric mineral aerosol deposition on the albedo of snow & sea ice: are snow and sea ice optical properties more important than mineral aerosol optical properties?
Knowledge of the albedo of polar regions is crucial for understanding a range of climatic processes that have an impact on a global scale. Light-absorbing impurities in atmospheric aerosols deposited on snow and sea ice by aeolian transport absorb solar radiation, reducing albedo. Here, the effec...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-01-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/16/843/2016/acp-16-843-2016.pdf |
| Summary: | Knowledge of the albedo of polar regions is crucial for understanding a range
of climatic processes that have an impact on a global scale. Light-absorbing
impurities in atmospheric aerosols deposited on snow and sea ice by aeolian
transport absorb solar radiation, reducing albedo. Here, the effects of five
mineral aerosol deposits reducing the albedo of polar snow and sea ice are
considered. Calculations employing a coupled atmospheric and snow/sea ice
radiative-transfer model (TUV-snow) show that the effects of mineral aerosol
deposits are strongly dependent on the snow or sea ice type rather than the
differences between the aerosol optical characteristics. The change in albedo
between five different mineral aerosol deposits with refractive indices
varying by a factor of 2 reaches a maximum of 0.0788, whereas the difference
between cold polar snow and melting sea ice is 0.8893 for the same mineral
loading. Surprisingly, the thickness of a surface layer of snow or sea ice
loaded with the same mass ratio of mineral dust has little effect on albedo.
On the contrary, the surface albedo of two snowpacks of equal depth,
containing the same mineral aerosol mass ratio, is similar, whether the
loading is uniformly distributed or concentrated in multiple layers,
regardless of their position or spacing. The impact of mineral aerosol
deposits is much larger on melting sea ice than on other types of snow and
sea ice. Therefore, the higher input of shortwave radiation during the summer
melt cycle associated with melting sea ice accelerates the melt
process. |
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| ISSN: | 1680-7316 1680-7324 |