The Radiative Impacts of Precipitating Ice on Arctic and Southern Ocean Sea Ice Simulations in GCMs
Abstract
Using the NCAR-CESM1 model and observations we show that a bias in sea-ice concentration is attributable to erroneous cloud-radiative interaction associated with the exclusion of downwelling long-wave heating from precipitating ice over Arctic and Southern Oceans. These biases resemble those in CMIP5 models which commonly exclude the radiative effects of precipitating ice. This missing radiative effects, in conjunction with overestimated surface albedo, leads to colder surface temperatures (TS), near surface-air temperatures (SAT) and the associated surface energy-budget adjustments. These biases in turn increases the sea-ice concentration in Arctic and Southern Oceans. The inclusion of the precipitating ice radiative effects reduces the negative model biases in surface radiative fluxes by more than 20 W m-2, TS and SAT by 2—4 K and positive sea-ice concentration by 30—40%, leading to a more realistic seasonal cycle compared with simulations lacking the snow-radiative effects. The findings have implications to the simulation of projection of changes associated with sea-ice in CMIP models.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMGC21A1054L
- Keywords:
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- 3355 Regional modeling;
- ATMOSPHERIC PROCESSESDE: 0750 Sea ice;
- CRYOSPHEREDE: 1843 Land/atmosphere interactions;
- HYDROLOGYDE: 4207 Arctic and Antarctic oceanography;
- OCEANOGRAPHY: GENERAL