AKHS?QFX?

[21marta]

Hi!

I am trying to find the formulas for surface exchange coefficient for heat and upward moisture flux from the surface. I already know that my fluxes are calculated in the module_sf_myjsfc, but I have no idea where is AKHS calculated? And hot to obtain TLOW?PLOW?QLOW?

In the attachment is my namelist_input file.






&time_control
run_hours = 30,
start_year = 1998,
start_month = 02,
start_day = 01,
start_hour = 00,
start_minute = 00,
start_second = 00,
history_interval = 10,
frames_per_outfile = 1,
restart = .false.,
restart_interval = 60,
io_form_history = 2,
io_form_restart = 2,
io_form_input = 2,
io_form_boundary = 2,
diag_print = 0,
debug_level = 0,
nocolons = .true.,
/

&domains
time_step = 1,
use_adaptive_time_step = .false.,
step_to_output_time = .true.,
min_time_step = 1,
min_time_step_den = 2,
max_dom = 1,
s_we = 1,
e_we = 201,
s_sn = 1,
e_sn = 201,
s_vert = 1,
e_vert = 61,
dx = 100,
dy = 100,
ztop = 2000,
max_ts_locs = 20,
ts_buf_size = 200
/

&physics
mp_physics = 4,
ra_lw_physics = 4,
ra_sw_physics = 2,
radt = 10,
swint_opt = 1,
sf_sfclay_physics = 2,
sf_surface_physics = 2,
bl_pbl_physics = 0,
bldt = 0,
cu_physics = 0,
isfflx = 1,
icloud = 0,
num_soil_layers = 4,
sst_skin = 1
seaice_threshold = 0.0
fractional_seaice = 1
seaice_albedo_opt = 0
seaice_albedo_default = 0.75
seaice_snowdepth_opt = 0
seaice_snowdepth_max = 1.e10
seaice_snowdepth_min = 0.001
seaice_thickness_opt = 0
seaice_thickness_default = 1.5
/
/

&dynamics
rk_ord = 3,
diff_opt = 2,
km_opt = 2,
damp_opt = 2,
zdamp = 200.0,
dampcoef = .003,
top_lid = .false.,
rad_nudge = 0,
smdiv = 0.1,
emdiv = 0.01,
epssm = 0.1,
time_step_sound = 6,
non_hydrostatic = .true.,
moist_adv_opt = 1,
/

&bdy_control
periodic_x = .true.,
symmetric_xs = .false.,
symmetric_xe = .false.,
open_xs = .false.,
open_xe = .false.,
periodic_y = .true.,
symmetric_ys = .false.,
symmetric_ye = .false.,
open_ys = .false.,
open_ye = .false.,
/

&grib2
/

&namelist_quilt
nio_tasks_per_group = 0,
nio_groups = 1,
/

PLEASE HELP!

 

[kwerner]

Hi,
I first would like to apologize for the delay in response to this. This originally was posted in the WRFDA section of the forum (and due to lack of resources, that group isn't able to tend to this forum often). It was just moved to the regular WRF physics section today, where I saw it.

Have you made any progress with this? It looks like these variables actually are calculated within module_sf_myjsfc.F. If you search within that file you should be able to find the variables in question (AKHS, TLOW, PLOW, QLOW) and find the calculations for them. They may include variables in their formulas that come from elsewhere in the module, but I believe it's all done within that one file.

 

[21marta]

Hi! I hope that someone will read this..
I agree, those variables are calculated in the same file, but the definition:
PLOW=PK(LMH)
TLOW=TK(LMH)
QLOW=QK(LMH)
only gives even more confusion :/
Because, I presume that LMH means lowest model height so...is it just temperature for the lowest level of the model? Or the half on the lowest model layer? Which temperature is it? Potential? Sensible?
It is all very confusing.

 

[kwerner]

Hi,
I agree it is a bit confusing. I had to do a bit of searching, but found the following:

1) PLOW = PK(LMH)
This is the pressure at the lowest layer above the ground.

2) TLOW = TK(LMH)
This is the perturbation potential temperature (theta-t0).

3) QLOW = QK(LMH)
This is the water vapor mixing ratio at the lowest layer above the ground.

Hopefully that helps!

Kelly

 

[21marta]

Thank You very very much!
I have one more question: on the basis of my namelist.input wrfhelp informed me that the HFX and QFX fluxes are calculated in module_sf_myjsfc.f
And there the equation for moisture heat flux is:
QFX=RLOW*AKHS*(QLOW-QZ0)*WETM
I assumed that WETM is 1 for sea ice and water, but what bothers me is where is the wind component in this equation? Accroding to literature it should be there.
Thank You in advance.

Best regards

 

[kwerner]

Hi
AKHS is proportional to USTAR, which is a function of wind speed.

Kelly

 

[21marta]

Thank You for your reply.
So, just to confirm, I do no have to include USTAR in a equation (QFX=RLOW*AKHS*(QLOW-QZ0)*WETM)?

 

[kwerner]

That is correct. It's already accounted for.