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Task 912-54-204: Development and Applications of the Goddard Multi-Scale Modeling
Framework
GEST Investigator: Jiun-Dar Chern
79
CODE 613.1
Collaborators: Wei-Kuo Tao (PI, GSFC 613.1), C. Peters-Lidard (GSFC 614.3), Bo-Wen Shen
(ESSIC), Toshihisa Matsui (GEST)
Description of Research
The representation of convective clouds and
cloud systems in a global climate model is one
of the most challenging problems in climate
modeling. To break the cloud parameterization
deadlock in global models, a new modeling
approach, the Multi-scale Modeling Framework
(MMF), was developed. The idea is to use
cloud-resolving model (CRM) in each column of
a general circulation model (GCM) to explicitly
represent small-scale and mesoscale cloud
processes and interactions among them. The use
of a GCM will enable global coverage, and the
use of a CRM will allow for better and more
sophisticated representation of model physics.
The MMF has been shown to substantially
reduce common systematic errors in climate
models. Coupled with forward satellite
simulators, the high-resolution CRM outputs
from the MMF can provide global detailed cloud
statistics that can be compared directly against
observations from NASA satellite platforms
such as the Tropical Rainfall Measuring Mission
(TRMM), the Moderate Resolution Imaging
Spectroradiometer (MODIS), Microwave Limb
Sounder (MLS), and the CloudSat. The main
objective of this research is to use NASA
satellite products for improving the cloud
microphysics schemes in CRM and the
representation of moist processes in climate
models.
Accomplishments during the Reporting Period
Based on the finite-volume General Circulation
Model (fvGCM) and 2D Goddard Cumulus
Ensemble Model (GCE), the Goddard MMF has
been successfully developed. The MMF has been
effectively applied and its performance tested for
two different climate scenarios, El Nino (1998)
and La Nina (1999), using observed sea surface
temperatures (SSTs). Overall, the MMF is
superior to fvGCM in simulating the geographical
distribution of precipitation, high cloud amount,
the Madden-Julian oscillation (MJO) signal, and
diurnal cycle of precipitation over land and ocean
(Tao et al. 2009). Despite some promising
preliminary results from the MMF, more
simulations are needed to explore the capabilities
and possible limitations of the system. The MMF
control runs have been performed from 2005 to
2007 to study the 2005 and 2006 hurricane
activities in the Atlantic basin and the regional
drought/flood variances over the Great Plains in
the summer season of 2006 and 2007. In addition,
several MMF short-term (monthly or seasonal)
simulations have been performed to assess the
performance of the MMF in simulating individual
Madden-Julian oscillation events, the effect of
terrain and model resolution, and the performance
of new cloud microphysical schemes.
In 2005, the Atlantic hurricane season featured a
record 15 hurricanes, with a record four
landfalling U.S. major hurricanes (i.e. categories
3-5 on Saffir-Simpson scale). However, the
hurricane activities in the Atlantic basin were near
normal with only five (5) hurricanes in 2006,
even with the prevailing favorable preseason
conditions. Two possible causes of foiling the
2006 hurricane forecasts have been suggested: the
cooling of the Atlantic basin by Saharan dust and
the anomalous upper-level convergence and
sinking motion across the Caribbean Sea due to
the El Nino activity. The Goddard MMF and
fvGCM two-year (2005-2006) control simulations
forced by the observed weekly sea surface
temperature show both models agree well with
the TRMM combined product in simulating more
precipitation during the 2005 season. The
preliminary results show the MMF has better
precipitation bias with less rainfall amount over
the North Atlantic. In addition, the dry areas
associated with the subtropical Bermuda high are
more realistic than that of the fvGCM. Both