Difference between pages "Direct effect from GLOMAP-mode aerosol to the Edwards-Slingo radiation scheme" and "ARCHER porting"

From UKCA
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Several of the [[UKCA Release Jobs]] have been ported from HECToR to ARCHER, and their [[UKCA_Release_Jobs#Job_List|jobids]] are detailed on that page.
The UKCA model is configured into the HadGEM3 climate model
 
with a double call to the radiation scheme to allow the
 
direct radiative effect from the GLOMAP-mode aerosol to be
 
calculated online in the model.
 
   
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==Timings==
For the existing CLASSIC aerosol scheme used
 
in HadGEM2-ES and previous HadGEM versions,
 
the aerosol is considered as an external
 
mixture of different aerosol types (sulphate,
 
biomass, soot, biogenic and sea-salt).
 
Then, for the direct aerosol forcing, the optical properties
 
from each of these types was considered separately.
 
The interface to the Edwards-Slingo radiation scheme used
 
in HadGEM is based on look-up tables (from Mie calculations)
 
for the optical properties of each particle type
 
as a function of relative humidity.
 
   
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[[File:CCMI_timings_ARCHER.png|300px|thumb|right|Scaling and efficiency profiling for N48L60 UKCa CheS+ on ARCHER]]
In contrast to CLASSIC, GLOMAP-mode assumes each mode
 
consists of an internal mixture of the different aerosol
 
components (e.g. sulphate, black carbon and organic carbon).
 
The water content is evaluated within this assumption using
 
the ZSR algorithm (Stokes and Robinson, 1966), using water activity data from Jacobson et al. (1996).
 
   
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The plot shows how UKCA scales when ported to ARCHER. The most efficient number of nodes to use is 3 (8x9), although the model will run fastest on 6 nodes (e.g. 16x9 or 12x12). Moving to 3 nodes from 6 will increase the run-time by 50%.
Whereas the look-up tables for the CLASSIC aerosol scheme were
 
based only on relative humidity and wavelength; for GLOMAP-mode, the
 
information on mean particle radius and composition for each
 
of the internally-mixed size modes is used. A volume-average
 
mixing rule is used over the components present (including water)
 
to calculate the real and imaginary parts of the refractive
 
index. The particle size determines the Mie parameter in
 
relation to the wavelength. The look-up tables have been
 
calculated based on the integrals across each of the
 
spectral bands for the short-wave and long-wave used by HadGEM.
 
   
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==Code Changes==
For more details about the interface to the Edwards-Slingo
 
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radiation scheme and the calculations of the optical properties
 
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===Cray cce Fortran Compiler===
of the aerosol, please contact Nicolas Bellouin (UK Met Office)
 
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nicolas.bellouin@metoffice.gov.uk.
 
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Corrections required for the Cray cce compiler on archer can be found on the [[Bugfixes#Cray_compiler_on_ARCHER|bugfixes page]].

Revision as of 16:12, 14 January 2014

Several of the UKCA Release Jobs have been ported from HECToR to ARCHER, and their jobids are detailed on that page.

Timings

Scaling and efficiency profiling for N48L60 UKCa CheS+ on ARCHER

The plot shows how UKCA scales when ported to ARCHER. The most efficient number of nodes to use is 3 (8x9), although the model will run fastest on 6 nodes (e.g. 16x9 or 12x12). Moving to 3 nodes from 6 will increase the run-time by 50%.

Code Changes

Cray cce Fortran Compiler

Corrections required for the Cray cce compiler on archer can be found on the bugfixes page.