57A014
Quantifying seasonal influence of stratiform mixed-phase
clouds on Arctic sea-ice growth rates
Gijs de Boer, William D. Collins, Surabi Menon, Elizabeth
Hunke, Edwin W. Eloranta
Corresponding author: Gijs de Boer –
GDeBoer@lbl.gov
Single-layer stratiform clouds are commonly observed at
high latitudes (Shupe and others, 2006; de Boer and others, 2009). Recently
several papers have linked record minimum sea-ice coverage in part to anomalous
patterns in low cloud coverage (e.g. Kay and others, 2008). Low-level
mixed-phase clouds may impact sea-ice growth/melting rates via their influence
on the atmospheric radiation budget as well as through frozen precipitation they
produce. These influences are naturally variable by season, dependent largely
upon sun angle and atmospheric temperature. In this study, we utilize multiple
years of cloud observations from surface-based remote sensors at Barrow, Alaska
(United States Department of Energy Atmospheric Radiation Measurement (US DOE
ARM) North Slope of Alaska site), and Eureka, Canada (National Oceanographic and
Atmospheric Administration and Canadian Network for the Detection of Arctic
Change Study for Environmental ARctic CHange (NOAA/CANDAC SEARCH) program), to
derive seasonal profiles of cloud properties such as liquid water content, ice
water content, precipitation rate, temperature and cloud depth. This information
is subsequently utilized in an atmospheric radiative transfer model (RRTM;
Clough and others, 2005) to derive surface shortwave and longwave radiative
fluxes. Finally, these fluxes, along with relevant temperature and precipitation
information, are used to drive the Los Alamos Sea Ice Model (CICE; Hunke and
Lipscomb, 2008) to determine the influence of these clouds on sea-ice growth
rates. In this work, we present seasonal and location-dependant differences in
cloud properties, along with a quantitative analysis of the influence that these
different cloud regimes have on sea-ice growth and decay rates. In addition, we
will discuss possible feedback mechanisms between these clouds and sea
ice.
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