Scheduled Downtime
On Tuesday 24 October 2023 @ 5pm MT the forums will be in read only mode in preparation for the downtime. On Wednesday 25 October 2023 @ 5am MT, this website will be down for maintenance and expected to return online later in the morning.
Normal Operations
The forums are back online with normal operations. If you notice any issues or errors related to the forums, please reach out to help@ucar.edu

liqflgsw, iceflgsw and inflgsw in RRTMG_SW for cloud optics parameterization

1

1475922792@qq_com

New Member
Dear all, In RRTMG of CAM5, the ice radiative properties seem to be got directly from CAM in the default simulation. And there are some options “inflgsw”, “iceflgsw” and “liqflgsw” in code used to select different parameterizations of cloud ice and liquid optical depth. Then I tried to change the values of these options in the code to use the Fu parameterization for ice cloud and Hu et al for liquid cloud. But the result of it is quite different from the default simulation. Some even seem to be very strange.  In the description of RRTMG_SW, it says, ‘The optical properties of water clouds are calculated for each spectral band from the Hu and Stamnes parameterization. The optical properties of ice clouds are calculated for each spectral band from the Fu parameterization, which assumes the ice crystals are hexagonal and randomly-oriented in space.’ But from the source code, it seems the cloud properties are not parameterized in that ways.  Have anyone encountered the similar question? Hope someone can solve my doubt.Thank you very much! Jocelyn
 
E

eaton

CSEG and Liaisons
RRTMG is implemented in CAM to use cloud and aerosol optical properties that are computed externally to the RRTMG code and passed to it.  The physical properties of the clouds that would be required to compute cloud optics are not passed.  In file radsw.F90 where the flags you mention are set you will also notice that the ice and liquid water paths (cicewp, cliqwp) and effective radius variables (rei, rel) are set to zero. 
 
E

eaton

CSEG and Liaisons
RRTMG is implemented in CAM to use cloud and aerosol optical properties that are computed externally to the RRTMG code and passed to it.  The physical properties of the clouds that would be required to compute cloud optics are not passed.  In file radsw.F90 where the flags you mention are set you will also notice that the ice and liquid water paths (cicewp, cliqwp) and effective radius variables (rei, rel) are set to zero. 
 
1

1475922792@qq_com

New Member
If I want to make it work, it needs to change not only liqflgsw, iceflgsw, inflgsw in radsw.f90, but also the data transmission of cliqwp and cicewp. Is that right? Jocelyn
 
1

1475922792@qq_com

New Member
If I want to make it work, it needs to change not only liqflgsw, iceflgsw, inflgsw in radsw.f90, but also the data transmission of cliqwp and cicewp. Is that right? Jocelyn
 
E

eaton

CSEG and Liaisons
The effective radius for the liquid droplets and ice crystals also appear to be required inputs.  The internal RRTMG calculations for cloud optical properties have never been tested in CAM to my knowledge. 
 
E

eaton

CSEG and Liaisons
The effective radius for the liquid droplets and ice crystals also appear to be required inputs.  The internal RRTMG calculations for cloud optical properties have never been tested in CAM to my knowledge. 
 
You must log in or register to reply here.
Top