Test Case 5: Cold air outbreak

This test case is 3D and does not require the radiation code. This page provides the background information on test case 5 and examples of run of test case 5 on various machines.

Background information (from Jon Petch)

As well as tropical deep convection (e.g. TOGA-COARE) and mid-latitude summer deep convection (e.g. ARM) the LEM can also be used to study convection in colder atmospheres. Whereas in the tropical and summer cases the melting level is high and nearly all surface precipitation is rain, in the colder atmosphere the melting level will be much lower and frozen hydrometeor species, particularly graupel, may contribute to the surface precipitation. Such a convective cold atmosphere case is referred to as a "cold air outbreak" and represents, say, a northerly cold plunge over mid-latitude oceans or springtime land. The convection is essentially surface forced, as the relatively warm land or sea heats the boundary layer and makes the atmosphere convectively unstable.

This cold air outbreak is an idealised case used by Kershaw (QJ, 1995) and Kershaw and Gregory (QJ, 1997). A simple thermodynamic profile and vertical wind shear and specified along with constant prescribed sensible and latent surface heat fluxes of 100 W/m2 and 400 W/m2 respectively. The model is initiated with low level random noise, and no other forcing (such as radiation) is present. Within an hour convection is established and timeseries and the typical mean properties over the second hour are shown below:

Profiles from the final hour. Typical timeseries.

The original case in Kershaw (1995) used only warm rain microphysics. However, the case presented here is used primarily as a test of the three phase double moment microphysics and deep convection in a 3-D domain.

Files required to run test case 5

The files needed to run this test case can be found in /home/lem/VER2.3/TEST_CASES/TEST5_2.3 and the table below indicates which files you'll need for which machines

	Turing (T3E - no longer available)	Department machines	Origins (i.e. wren, fermat or green)	Newton
run...f	runTEST5_2.3.f	runTEST5_2.3-m.f	runTEST5_2.3.f	runTEST5_2.3.f
end...f	endTEST5_2.3.f	endTEST5_2.3.f	endTEST5_2.3.f	endTEST5_2.3.f
nmlsetup...	nmlsetupTEST5_2.3	nmlsetupTEST5_2.3	nmlsetupTEST5_2.3	nmlsetupTEST5_2.3
nmlchain...	nmlchainTEST5_2.3	nmlchainTEST5_2.3	nmlchainTEST5_2.3	nmlchainTEST5_2.3
model...	modelTEST5_2.3	modelTEST5_2.3	modelTEST5_2.3-n	modelTEST5_2.3-n

Runs for Test Case 5

Computer	Run No	Version	PEs	IIP, JJP, KKP	Time Taken	Results
Newton	131	2.3	16	128, 128, 60	1.90 hrs	The final hour Timeseries
Origins	31	2.3	16	128, 128, 60	~6 hrs	The final hour Timeseries
GRID	56	2.3	1	40, 40, 60	20.0 hrs	The final hour Timeseries
T3E at Met Office	N/A	2.2	16	128, 128, 60	unknown	The final hour Timeseries
Turing	708	2.2	16	128, 128, 60	unknown	The final hour Timeseries