Dear arango, Kate, and wilkin,
I have looked into many discussions about the grid angle and the rotation of wind and ocean current velocity, but got more confused !
1. When I prepare the wind forcing, should I rotate the wind direction from geometrical eastward/northward to grid xi/eta in my forcing .nc file ?
2. When I prepare the ocean current velocity initial, boundary and climatology .nc files, should I rotate their direction from geometrical eastward/northward to grid xi/eta ?
3. I found that if I have defined #CURVGRID in the preprocessor, the /ROMS/Nonlinear/set_data.F rotate the wind again ! So, dose that mean, if I have defined #CURVGRID, I must not rotate the wind direction in my forcing .nc file ?
4. I also found that the /ROMS/Nonlinear/set_data.F doesn't rotate the ocean current velocity, so, there is no relationship between rotation of ocean current velocity and #CURVGRID ?
5. If CURVGRID and wind forcing file ratation are repeated in question 3. There is pretty large angle between xi/eta and east/north in my grid, is it reasonable to undefine CURVGRID and use a rotated wind forcing ?
6. Is there relation among these three: A. the rotation of the wind and ocean current; B #CURVGRID in the preprocessor; C spherical/Cartesian in the grid file ?
7. Dose the sitution change with the version of ROMS ?
Looking forward to hearing from you soon.
Wish you good heath and happiness !
Joe Smith
angle, wind, ocean current
-
- Posts: 26
- Joined: Wed Jul 19, 2017 4:03 pm
- Location: Zhejiang University
angle, wind, ocean current
- Attachments
-
arctic-20km.h
- (7.99 KiB) Downloaded 107 times
-
- Posts: 26
- Joined: Wed Jul 19, 2017 4:03 pm
- Location: Zhejiang University
Re: angle, wind, ocean current
I have interpolated forcing, initial, boundary and climatological file into roms grid. The key point is whether rotate wind and ocean current velocity.
Re: angle, wind, ocean current
If you are providing Uwind,Vwind in a netcdf file and having ROMS interpolate from the Uwind,Vwind lon,lat coordinates then ROMS will apply the angle rotation in the regridding step. You will receive confirmation that a regrid is being done in the standard output, e.g.:1. When I prepare the wind forcing, should I rotate the wind direction from geometrical eastward/northward to grid xi/eta in my forcing .nc file ?
If you give wind forcing as stresses sustr,svstr on the staggered grid with dimensions that match u,v, then ROMS will not regrid. stdout should confirm regrid = F.GET_2DFLD_NF90 - surface u-wind component, 2007-01-01 21:00:00.00
(Grid=01, Rec=8, Index=1, File: Uwind_narr_NENA_2007.nc)
(Tmin= 365.0000 Tmax= 729.8750) t = 365.8750
(Min = -5.36645855E+00 Max = 7.58490888E+00) regrid = T
No, initial, boundary and climatology files are all in ROMS space and coordinates. The file formats for initial and climatology are exactly the same (dimensions and coordinates) as ROMS output history and averages (etc.) files. Inspecting the dimensions, you will see that u and v variables have different dimensions corresponding to their respective staggered Arakawa-C grid positions (i.e. they are not simply components of a total vector defined at the model rho points).2. When I prepare the ocean current velocity initial, boundary and climatology .nc files, should I rotate their direction from geometrical eastward/northward to grid xi/eta ?
The only place that rotation comes in into water velocities is on output if you request east,north velocities
Code: Select all
Hout(idu3dE) == T ! u_eastward 3D U-eastward at RHO-points
Hout(idv3dN) == T ! v_northward 3D V-northward at RHO-points
As I say above, do not rotate Uwind,Vwind. Water velocities are in ROMS coordinate directions AND split out to their _u and _v positions.3. I found that if I have defined #CURVGRID in the preprocessor, the /ROMS/Nonlinear/set_data.F rotate the wind again ! So, dose that mean, if I have defined #CURVGRID, I must not rotate the wind direction in my forcing .nc file ?
4. I also found that the /ROMS/Nonlinear/set_data.F doesn't rotate the ocean current velocity, so, there is no relationship between rotation of ocean current velocity and #CURVGRID ?
The documentation is terse, but such as it is, WikiROMS gives this about CURVGRID: https://www.myroms.org/wiki/CURVGRID5. If CURVGRID and wind forcing file ratation are repeated in question 3. There is pretty large angle between xi/eta and east/north in my grid, is it reasonable to undefine CURVGRID and use a rotated wind forcing ?
IF dmde or dndx or angle is non-zero, then you should activate this option. The curvature of the grid requires additional metric terms in the momentum equations. The rotation of a grid requires the grid angle to be non-zero. The grid angle is needed for such features as to rotate Uwind and Vwind to the grid (for example).
All ocean current inputs are in ROMS coordinates. See CURVGRID above. I don't know what happens for non-spherical coordinates.6. Is there relation among these three: A. the rotation of the wind and ocean current; B #CURVGRID in the preprocessor; C spherical/Cartesian in the grid file ?
No.7. Dose the sitution change with the version of ROMS ?
John Wilkin: DMCS Rutgers University
71 Dudley Rd, New Brunswick, NJ 08901-8521, USA. ph: 609-630-0559 jwilkin@rutgers.edu
71 Dudley Rd, New Brunswick, NJ 08901-8521, USA. ph: 609-630-0559 jwilkin@rutgers.edu
Re: angle, wind, ocean current
你用的哪一个版本的roms呢??
2023年推出的新版版似乎有些cpp不需要在h文件中定义了
2023年推出的新版版似乎有些cpp不需要在h文件中定义了