too large surface velocity

General scientific issues regarding ROMS

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cheng_dada
Posts: 10
Joined: Fri Feb 26, 2021 2:20 pm
Location: Shantou University

too large surface velocity

#1 Unread post by cheng_dada »

Hello everyone,
I am running a test, and the surface velocity in the ROMS result file is obviously too large compared with hycom.
roms result:
roms_u_current.png
hycom data:
hycom_water_u.png
Then I output uwind and vwind in his file, and compared with the input wind field of 10m, the output uwind of roms is also too large.
roms:
roms_uwind.png
GFS:
gfs_uwind.png
Is that normal? Is my excessive surface flow a problem with the wind field?
I defined bulk_fluxes to calculate wind stress. I saw on the forum that the wind stress calculated by bulk_fluxes would be too large. Is this the reason?
this is my define file:
7785d86ca1a5de4a0c542a8f785ff85.png
log file:
2024051300.dat
(1.25 MiB) Downloaded 178 times

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wilkin
Posts: 922
Joined: Mon Apr 28, 2003 5:44 pm
Location: Rutgers University
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Re: too large surface velocity

#2 Unread post by wilkin »

Judging from your plots the geometry of your grids is simple east-west rectangular coordinates. But the log reports a range of values for angler from -90 degrees to 270 degrees:

Grid 01:

Code: Select all

  GET_GRID_NF90    - angle between XI-axis and EAST: angler
                      (Grid = 01, File: /home/roms/input/NH_grid.nc)
                      (Min = -1.57079633E+00 Max =  4.71238359E+00)
(Values are in radians)

You might be unwittingly rotating your winds.

Moreover, for Grid 02 you have

Code: Select all

  GET_GRID_NF90    - angle between XI-axis and EAST: angler
                      (Grid = 02, File: /home/roms/input/ZH_roms_grid_ref5.nc)
                      (Min = -1.57084583E+00 Max = -1.57071597E+00)
which suggests everything gets rotated by -90 degrees.
John Wilkin: DMCS Rutgers University
71 Dudley Rd, New Brunswick, NJ 08901-8521, USA. ph: 609-630-0559 jwilkin@rutgers.edu

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