Design and performance of a new cloud microphysics scheme developed for the ECHAM general circulation model

1996 ◽  
Vol 12 (8) ◽  
pp. 557-572 ◽  
Author(s):  
U. Lohmann ◽  
E. Roeckner
Keyword(s):  
General Circulation Model ◽  
General Circulation ◽  
Circulation Model ◽  
Cloud Microphysics ◽  
Microphysics Scheme ◽  
And Performance

scholarly journals Design and Performance Analysis of a Massively Parallel Atmospheric General Circulation Model

2000 ◽  
Vol 8 (1) ◽  
pp. 49-57 ◽  
Author(s):  
Daniel S. Schaffer ◽  
Max J. Suárez
Keyword(s):  
General Circulation Model ◽  
General Circulation ◽  
High Performance ◽  
Degrees Of Freedom ◽  
Parallel Machines ◽  
Atmospheric General Circulation Model ◽  
Circulation Model ◽  
Massively Parallel ◽  
Atmospheric General Circulation ◽  
And Performance

In the 1990's, computer manufacturers are increasingly turning to the development of parallel processor machines to meet the high performance needs of their customers. Simultaneously, atmospheric scientists studying weather and climate phenomena ranging from hurricanes to El Niño to global warming require increasingly fine resolution models. Here, implementation of a parallel atmospheric general circulation model (GCM) which exploits the power of massively parallel machines is described. Using the horizontal data domain decomposition methodology, this FORTRAN 90 model is able to integrate a 0.6° longitude by 0.5° latitude problem at a rate of 19 Gigaflops on 512 processors of a Cray T3E 600; corresponding to 280 seconds of wall-clock time per simulated model day. At this resolution, the model has 64 times as many degrees of freedom and performs 400 times as many floating point operations per simulated day as the model it replaces.

scholarly journals Resolved Snowball Earth Clouds

2014 ◽  
Vol 27 (12) ◽  
pp. 4391-4402 ◽  
Author(s):  
Dorian S. Abbot
Keyword(s):  
Radiative Forcing ◽  
General Circulation ◽  
Circulation Model ◽  
Cloud Amount ◽  
Cloud Microphysics ◽  
Snowball Earth ◽  
Geochemical Data ◽  
Microphysics Scheme ◽  
Cloud Resolving Model ◽  
Cloud Ice

Abstract Recent general circulation model (GCM) simulations have challenged the idea that a snowball Earth would be nearly entirely cloudless. This is important because clouds would provide a strong warming to a high-albedo snowball Earth. GCM results suggest that clouds could lower the threshold CO2 needed to deglaciate a snowball by a factor of 10–100, enough to allow consistency with geochemical data. Here a cloud-resolving model is used to investigate cloud and convection behavior in a snowball Earth climate. The model produces convection that extends vertically to a similar temperature as modern tropical convection. This convection produces clouds that resemble stratocumulus clouds under an inversion on modern Earth, which slowly dissipate by sedimentation of cloud ice. There is enough cloud ice for the clouds to be optically thick in the longwave, and the resulting cloud radiative forcing is similar to that produced in GCMs run in snowball conditions. This result is robust to large changes in the cloud microphysics scheme because the cloud longwave forcing, which dominates the total forcing, is relatively insensitive to cloud amount and particle size. The cloud-resolving model results are therefore consistent with the idea that clouds would provide a large warming to a snowball Earth, helping to allow snowball deglaciation.

A New Two-Moment Bulk Stratiform Cloud Microphysics Scheme in the Community Atmosphere Model, Version 3 (CAM3). Part II: Single-Column and Global Results

2008 ◽  
Vol 21 (15) ◽  
pp. 3660-3679 ◽  
Author(s):  
A. Gettelman ◽  
H. Morrison ◽  
S. J. Ghan
Keyword(s):  
General Circulation ◽  
Circulation Model ◽  
Cloud Microphysics ◽  
Number Concentration ◽  
Radiation Budget ◽  
Cloud Particle ◽  
Microphysics Scheme ◽  
Community Atmosphere Model ◽  
Single Column ◽  
Rain Drops

Abstract The global performance of a new two-moment cloud microphysics scheme for a general circulation model (GCM) is presented and evaluated relative to observations. The scheme produces reasonable representations of cloud particle size and number concentration when compared to observations, and it represents expected and observed spatial variations in cloud microphysical quantities. The scheme has smaller particles and higher number concentrations over land than the standard bulk microphysics in the GCM and is able to balance the top-of-atmosphere radiation budget with 60% the liquid water of the standard scheme, in better agreement with retrieved values. The new scheme diagnostically treats both the mixing ratio and number concentration of rain and snow, and it is therefore able to differentiate the two key regimes, consisting of drizzle in shallow, warm clouds and larger rain drops in deeper cloud systems. The modeled rain and snow size distributions are consistent with observations.

scholarly journals Description and performance of the UIUC 24-layer stratosphere/troposphere general circulation model

2000 ◽  
Vol 105 (D14) ◽  
pp. 17925-17954 ◽  
Author(s):  
Fanglin Yang ◽  
Michael E. Schlesinger ◽  
Eugene Rozanov
Keyword(s):  
General Circulation Model ◽  
General Circulation ◽  
Circulation Model ◽  
And Performance
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