Ring pattern in Non-Convective Precipitation (NCP) with variable-resolution mesh (60 km–3 km)

[freddynazo]

Hi everyone,

I'm running an MPAS simulation using a variable-resolution mesh (60 km to 3 km). When plotting the non-convective precipitation (NCP), I noticed a ring-shaped feature, and I'm trying to understand what might be causing it.


Just to clarify:

• I did not use the convection-permitting suite.
• I'm using the mesoscale_reference physics suite.

I've attached both the namelist file and the corresponding image for reference.


Has anyone encountered something similar or have any insight into what could be driving this pattern?



&nhyd_model
config_time_integration_order = 2
config_dt = 15.0
config_start_time = '2005-08-27_16:00:00'
config_run_duration = '07_00:00:00'
config_split_dynamics_transport = true
config_number_of_sub_steps = 2
config_dynamics_split_steps = 3
config_horiz_mixing = '2d_smagorinsky'
config_visc4_2dsmag = 0.05
config_scalar_advection = true
config_monotonic = true
config_coef_3rd_order = 0.25
config_epssm = 0.1
config_smdiv = 0.1
config_len_disp = 3000.0
/
&damping
config_zd = 22000.0
config_xnutr = 0.2
/
&limited_area
config_apply_lbcs = false
/
&io
config_pio_num_iotasks = 0
config_pio_stride = 1
/
&decomposition
config_block_decomp_file_prefix = 'x20.835586.graph.info.part.'
/
&restart
config_do_restart = false
/
&printout
config_print_global_minmax_vel = true
config_print_detailed_minmax_vel = false
/
&IAU
config_IAU_option = 'off'
config_IAU_window_length_s = 3600.
/
&physics
config_sst_update = true
config_sstdiurn_update = false
config_deepsoiltemp_update = false
config_radtlw_interval = '01:00:00'
config_radtsw_interval = '01:00:00'
config_bucket_update = 'none'
config_physics_suite = 'mesoscale_reference'
/
&soundings
config_sounding_interval = 'none'
/

 

[mgduda]

Looking at the center plots on the top and bottom rows, I can see the ring you described in the top NCP (non-convective precip) plot, but I don't see a similar patter in the bottom TP (total precip?) plot. If there's no ring in the total precip, it would be worth checking whether there is a ring in the convective precip field that complements the ring in the non-convective precip.

In general though, I can't think of any explanation for why the model would produce such a pattern, either as a mesh artifact or from the nTiedtke scheme.