Questions about precipitation fluxes and effective radius

[Wei-Wei]

Dear all, 

I'm confused by several questions below now:

1. According to the user's manual 3.2, precipitation fluxes are used to derive mixing ratios. Since we already have mixing ratios from our model output, do we still need precipitating fluxes? Or we can just set "use_precipitation_fluxes" to false in the name list?

2. How is this precipitation fluxes used in COSP? Is it only for deriving mixing ratio? Or do other calculations also need this precipitation fluxes?

3. How the effective radius is calculated or set if it is not provided by out model output?

Would you like to help me out of these difficulties? Many many thanks! 

Wei-Wei 

[Bodas-Salcedo, Alejandro]

Hello,

 

> 1. According to the user's manual 3.2, precipitation fluxes are used to derive mixing ratios. Since we already have mixing ratios from our model output, do we still need  

> precipitating fluxes? Or we can just set "use_precipitation_fluxes" to false in the name list? 

 

That is only possible if NCOLUMS=1. In that case you need to pass the mixing ratios in the precipitation fluxes arrays.

 

> 2. How is this precipitation fluxes used in COSP? Is it only for deriving mixing ratio? Or do other calculations also need this precipitation fluxes? 

 

They are used to derive the mixing ratios, which are only used by the radar simulator in the standard version.

 

>  3. How the effective radius is calculated or set if it is not provided by out model output? 

 

For the lidar simulator, you need to provide the effective radius. For the radar, you can provide the effective radius (and setting use_reff=.true.) or use a default value for either the total particle number concentration or the particle mean diameter in the HCLASS_P1/HCLASS_P2 coefficients, defined in cosp_constants.F90. The HCLASS table is explained in Section 3.4.

 

Regards,

 

Alejandro

[Wei-Wei]

Hi Alejandro,

Thanks for your explanations!

I think these can explain my problems.
BTW, I find our model output mixing ratio is only for the non-
precipitating part. I think, the precipitation fluxes are used to
derive the precipitating mixing ratio.

Thanks,

Wei-Wei

On Jan 27, 3:18 am, "Bodas-Salcedo, Alejandro"