M3DRY Error - Negative Dry Deposition Velocity

WRF-CMAQ
1

Hi everyone,

I’m running a two-way WRFv3.8-CMAQv5.2 run across CONUS at 4km and am having issues with the M3DRY routine. My run is crushing within the first ~15min with the error suggesting negative dry deposition values. I know there has been some similar discussions on this topic in this forum however these seem to be related to NaN dry deposition values which doesn’t seem to be our issue.
namelist.input.txt (6.7 KB)

image

Any suggestions on how to tackle this would be appreciated.

Thanks,
Sara

1 Like
2

Hi Sara,

Please try to reduce the wrf time step size (maybe by half). If it does not resolve your problem, please let me know directly.

Cheers,
David

3

Hi @wong.david-c ,

Thanks for your reply. We are attempting to run this simulation with a tstep of 6 seconds as shown in the attached namelist.input. Isn’t that already scaled down enough from the suggested 6*dx which would be 24 seconds in this case. I’m also attaching our twoway script in case useful.

Thanks,
Sara
twoway_model_run_script_CONUS4K_d02_201607_part1.txt (41.2 KB)

4

Hi Sara,

I have examined the run script you have provided.
There are a few differences between yours and the one in the released model:

                                            EPA           user

kfeta_trigger = 0 2
cugd_avedx = 3
num_soil_cat = 4
sf_urban_physics = 0
usemonalb = .true.
prec_acc_dt = 60
guv = 0.00005 0.0001
gt = 0.00005 0.0001
if_ramping = 1 0
rk_ord = 3
spec_bdy_width = 5 1
relax_zone = 4 0

I confess that I am not a WRF power user nor a meteorologist, but I think it won’t be a bad idea to try with the original settings.

Cheers,
David

5

Hi Sara,

I just realized (after posting the last reply), the format of the table was destroyed. Anyway after the equal sign, the first column refers to the option used in the released run script and the second column refers to your option. The notion “-” means not used and here is the table one more time.

                                                   EPA            user
 kfeta_trigger                     =               0                2
 cugd_avedx                        =                -               3
 num_soil_cat                      =                -               4
 sf_urban_physics                  =                -               0
 usemonalb                         =                -             .true.
 prec_acc_dt                       =                -              60
 guv                               =             0.00005          0.0001
 gt                                =             0.00005            0.0001
 if_ramping                        =                1                0
 rk_ord                            =                -                3
 spec_bdy_width                    =                5               1
 relax_zone                        =                4               0

Cheers,
David