[pccgrads] Fwd: Aaron Donohoe Seminar, tomorrow 9/9/2014, 10:30, APL Henderson Hall, 6th Floor

Luanne Thompson luanne at uw.edu
Mon Sep 8 15:14:46 PDT 2014


Speaker: Aaron Donohoe

Title: GLOBAL SCALE ENERGY FLUXES: Comparison of Observational Estimates
and
Model Simulations

Time: Tuesday, September 9, 10:30 AM <------------ NOTE Day and TIME

(Coffee/Tea, Cookies and Conversation at 10:00 AM)

Place: APL Hardisty Conference Center, 6th floor

Abstract:

Observational estimates and model simulations of global scale energy fluxes
in the climate
system are compared for 3 different spatial-temporal scales: 1.the global
mean radiative
balance of the climate system; 2. the poleward energy transport in each
hemisphere; 3.
the seasonal cycle of atmospheric heating and temperature. We demonstrate
that, in both
models and observations, the vast majority of the global mean planetary
albedo is due to
cloud reflection (88%) while surface reflection plays a secondary role
(12%). The two
hemispheres have nearly identical planetary albedos in the observations
whereas they
differ substantially in climate models.

The poleward energy transport in climate models differs by 20% and is
biased low, relative
to observations, in the southern hemisphere. The inter-model spread in
poleward heat
transport is a consequence of the equator to pole gradient in planetary
albedo which
itself is due to differences in cloud reflection. The seasonal cycle of
atmospheric
heating in the extratropics is primarily due to shortwave absorption in the
atmosphere and
is opposed by energy exchange with the surface; on seasonal timescales, the
atmosphere is
heated from above and cooled at the surface. This result is consistent
between models and
observations. In simulations of global warming, the seasonal cycle of
temperature is
enhanced aloft due to shortwave absorption by water vapor and reduced at
the surface due
to the melting of sea ice which exposes the atmosphere to the thermal
inertia of the
ocean.
--




--
LuAnne Thompson
Director, Program on Climate Change
Professor of Oceanography
Adjunct Professor Physics and Atmospheric Sciences

Office: 206 543 9965
Cell: 206 676 2685

twitter @UWPCC

faculty.washington.edu/luanne/
www.uwpcc.washington.edu/
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