Changes between Version 9 and Version 10 of doc/app/bulk_cloud_parameters

Timestamp:

Sep 26, 2018 1:41:33 PM (6 years ago)

Author:

schwenkel

Comment:

--

doc/app/bulk_cloud_parameters

@@ -35 +35 @@
 The following values are allowed:\\\\
 '' 'saturation_adjust' ''\\\\
-      Simple saturation adjustment scheme (also known as 0%-or100% scheme), in which a grid volume is either saturated or subsaturated. Detailed information about the condensation scheme is given in the description of the [[cloud physics module]] (pdf-file). Supersaturations are instantaneously condensed to liquid water. No precipitation is produced. If precipitation is important, use 'kessler or 'seifert_beheng'. \\\\
+      Simple saturation adjustment scheme (also known as 0%-or100% scheme), in which a grid volume is either saturated or subsaturated. Detailed information about the condensation scheme is given in the description of the cloud physics. Supersaturations are instantaneously condensed to liquid water. No precipitation is produced. If precipitation is important, use 'kessler, 'seifert_beheng' or 'morrison'. \\\\
 '' 'kessler' ''\\\\
       One-moment cloud microphysics according to Kessler (1969). It is also based on the saturation adjustment scheme to diagnose cloud water. However, it allows precipitation if the liquid cloud water exceeds a threshold value. This water is instantaneously removed from the model domain. Additionally,  liquid cloud water is allowed to sediment if [#cloud_water_sedimentation cloud_water_sedimentation] is set to true.
@@ -41 +41 @@
       Two-moment cloud microphysics according to Seifert and Beheng (2006). It is also based on the saturation adjustment scheme to diagnose cloud water. The cloud drop number concentration is set via [#nc_const nc_const]. Rain water and hence precipitation is treated with two additional prognostic equations for rain water mixing ratio and rain drop concentration, including autoconversion, accretion, selfcollection, breakup, evaporation, and sedimentation. Ventilation effect on evaporation is steered by [#ventilation_effect ventilation_effect] and set to true per default. Sedimentation can be controlled via [#c_sedimentation c_sedimentation], [#limiter_sedimentation limiter_sedimentation]. Turbulence effects on accretion and autoconversion are steered via [#collision_turbulence collision_turbulence]. Additionally,  liquid cloud water is allowed to sediment too if [#cloud_water_sedimentation cloud_water_sedimentation] is set to true.\\\\
 '' 'morrison' '' \\\\
-      Two-moment cloud microphysics according to Seifert and Beheng (2006), Khairoutdinov and Kogan (2000), Khvorostynaov and Curry (2006) and Morrison and Grabowski (2007). The 'morrison'-scheme can be understood as an extension of the implemented 'seifert_beheng'-scheme. In comparison to the 'seifert_beheng'-scheme there are three main differences. First, instead of saturation adjustment the diffusional growth is parametrized while calculating condensation/evaporation rates. Second, the activation is considered with a simple Twomey activation-scheme. For this also Koehler-theory can take into account with the parameter [#curvature_solution_effects_bulk curvature_solution_effects_bulk] = T. The background aerosol concentration, which also determines the maximum number of activated cloud droplets, can be prescribed with [#na_init na_init]. Thirdly, the number concentration of cloud droplets (nc) and the cloud water mixing ratio (qc) are prognostic quantities. This allows a change of the cloud droplet number which is also considered for all microphysical processes. \\\\
+      Two-moment cloud microphysics according to Seifert and Beheng (2006), Khairoutdinov and Kogan (2000), Khvorostynaov and Curry (2006) and Morrison and Grabowski (2007). The 'morrison'-scheme can be understood as an extension of the implemented 'seifert_beheng'-scheme. In comparison to the 'seifert_beheng'-scheme there are three main differences. First, instead of saturation adjustment the diffusional growth is parametrized while calculating condensation/evaporation rates explicitly. However, for a appropriate usage of this scheme the time-step must smaller than the diffusional growth relaxation time. Usually, this is in the order of 1-2 seconds. Second, the activation is considered with a simple Twomey activation-scheme. For this also Koehler-theory can take into account with the parameter [#curvature_solution_effects_bulk curvature_solution_effects_bulk] = T. The background aerosol concentration, which also determines the maximum number of activated cloud droplets, can be prescribed with [#na_init na_init]. Thirdly, the number concentration of cloud droplets (nc) and the cloud water mixing ratio (qc) are prognostic quantities. This allows a change of the cloud droplet number which is also considered for all microphysical processes. \\\\
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