fdda

[ito-tmm]

Hi,

My WRF model is overestimating wind speeds for the entire simulation period although simulated wind directions seem to reasonably match with observed data. I'm trying to tackle this issue by using the fdda option, however, simulated wind speeds remain higher than observed data despite the addition of the fdda parameters to my namelist. The below is the fdda section of my namelist. What parameters would you change or add to lower simulated wind speeds? Would you use a different option rather than fdda? Any advice would be much appreciated!

&fdda
grid_fdda = 1, 1,
gfdda_inname = "wrffdda_d<domain>",
gfdda_end_h = 99999, 99999,
gfdda_interval_m = 360, 360,
fgdt = 0, 0,
if_no_pbl_nudging_uv = 0, 0,
if_no_pbl_nudging_t = 0, 0,
if_no_pbl_nudging_q = 0, 0,
if_zfac_uv = 0, 0,
if_zfac_t = 0, 0,
if_zfac_q = 0, 0,
guv = 1.0e-4, 1.0e-4,
gt = 5.0e-5, 3.0e-5,
gq = 5.0e-5, 3.0e-5,
if_ramping = 0,
dtramp_min = 60.0,
io_form_gfdda = 2,

Thank you in advance,
TI

 

[Ming Chen]

Please add the option topo_wind = 1 or 2, then try again. Hope this option might give you better wind simulations. Note that with this option, you must also run with YSU PBL scheme.