2011 - Cooperative Institute for Research in Environmental Sciences ...

of the complex processes not available from other field program
data. The analysis provides a basis for future testing of
the generality of the results, and contributes to better physical
understanding of multi-year analyses of melt-season
trends from less extensive data sets. A paper describing the
generality of the SHEBA results using the ASCOS observations
and the Soviet data is in preparation.
Milestone 2. Using a Weather Research and Forecasting
(WRF) or 1-D model, simulate select cases from SHEBA,
ASCOS, AMISA and other field programs to a) evaluate the
model representation of the observed physical processes
and b) suggest improvements to related parameterizations
when possible. Improvements to the parameterization of
turbulent fluxes and surface albedo will be tried.
Simulations of a springtime Arctic stratocumulus cloud
over sea ice near Barrow during the 2008 Indirect and
Semi-Direct Aerosol Campaign (ISDAC) campaign were
done using a large-eddy simulation configuration of the
WRF model. Diagnostics of the dynamic and thermodynamic
interactions within the cloud and the surrounding
environment were carried out to understand the processes
by which these types of clouds are able to maintain
themselves. Features found to be key for this maintenance
include a shallow upper entrainment zone acting as a
moisture source for the cloud from a humidity inversion
above cloud top; mall-scale cloud-top turbulence facilitating
this moisture transport; and larger-scale convective cells
encompassing the cloud and a sub-cloud region driven by
cloud-top cooling. The moisture inversion coinciding with
the temperature inversion at cloud top appears to be a feature
unique to Arctic stratocumulus compared to subtropical
ones. Moisture and energy transport from the surface
was found to have minimal impact on the cloud formation
and maintenance. A paper describing the results has been
submitted. This milestone is also enhanced by contributions
to an internationally collaborative paper validating
surface energy fluxes in a regional climate model over East
Antarctica.
Milestone 3. In collaboration with E. Andreas, use the SURFA
global Numerical Weather Prediction (NWP) surface flux
archive to examine the Arctic surface energy budget and its
sensitivity to surface flux parameterizations
The Surface Flux Analysis (SURFA) data set was not
used, and hence the sensitivity of the modeled surface energy
budgets to surface flux parameterizations was not studied.
However, work validating the surface energy fluxes in four
reanalysis data sets over Arctic sea ice was completed, and
this work revealed significant sensitivity of the various terms
of the surface energy budget to the representation of cloud,
surface and turbulent processes. In this study, meteorological
parameters, turbulent fluxes, cloud properties, radiative fluxes
and the surface energy budget from ERA-40 (the European
Centre for Medium-Range Weather Forecasts [ECMWF] 40-
Year Re-analysis), ERA-Interim, National Centers for Environmental
Predication/Department of Energy (NCEP/DOE) and
JRA-25 (Japanese 25-year reanalysis) reanalyses are compared
to observations from the Surface Heat Budget of the Arctic
Ocean (SHEBA), one of very few year-long measurement
programs on the Arctic sea ice measuring surface fluxes and
cloud properties. Seven-day running means of reanalysis and
observational data were compared to understand how well
the reanalyses represent the basic meteorological parameters
and the processes producing the energy fluxes to the sea ice.
All reanalyses represent basic atmospheric state variables well,
with annual mean errors of 3.3-3.6% for ECMWF products
and 5.3-5.4% for JRA-25 and NCEP/DOE. However, they have
trouble simulating turbulent and radiative fluxes. Individual
flux terms have larger biases than net components, indicating
the presence of compensating errors (i.e., net fluxes are realistic
for the wrong reasons). RMS (root-mean-square) errors of
individual fluxes are 5.7-7.1 Wm-2 for the NCEP products,
13.6 Wm-2 for JRA-25 and 21.5 W m-2 for NCEP/DOE. All reanalyses
produce negative mean biases for the annual surface
energy balance, with three of the reanalyses indicating a net
gain of surface sea ice during a year for which observations
showed a loss of 76 cm of ice. Hence, improved representations
are needed of relationships between basic meteorological
parameters, cloud properties and individual components in
the surface energy budget. During 2010-2011, these results
are described in the University of Colorado master’s thesis of
Cassandra Wheeler, and a manuscript describing these results
is being prepared for publication.
CSV-05 Climate Research
Database Development
n NSIDC-01 Digitization of Analog Cryospheric Data Under
the Climate Database Modernization Program
n NSIDC-03 World Data Center for Glaciology, Boulder—Current
Programs
NSIDC-01DigitizationofAnalogCryosphericData
undertheClimateDatabaseModernizationProgram
FEDERAL LEAD: CARL GROENEVELD
CIRES LEAD: JANE BEITLER
NOAA Goal 2: Climate
Project Goal: Scan and make available online data from
NSIDC’s analog collections so that it is more easily located,
browsed and obtained by users.
Clockwise, from top left:
Bird’s-eye aerial ice reconnaissance
imagery taken in 1973;
Wilkes Station, Antarctica,
1958, as photographed by
John T. Hollin during the International
Geophysical Year;
Muir Glacier, as photographed
by Frank LaRoche in 1893.
From the Glacier Photograph
Collection, National Snow
and Ice Data Center.
CIRES Annual Report 2011 119