GETM cartesian bathy info

[Bjarne Büchmann]

Dear Wizards,

 

I am in the process of creating a GETM-setup based on a Cartesian bathymetry (in the Arctic).

 

For reference, I look at the box-Cartesian case: getm-setups/box_cartesian/topo.nc

It appears that the necessary dimensions and variables are:

 

#   dimensions: x,y

#   variables:

#    int grid_type=1

#    double x(x)

#    double y(y)

#    double bathymetry(y,x)

#    double latc(y, x) # latitude of T-points

#    double lonc(y, x) # longitude of T-points

#    double convc(y,x) # grid rotation in T-points

 

I believe that I understand all these, except that I may be somewhat in doubt about the exact definition of convc. Obviously, it should be the rotation of the individual cell relative to North, but I would very much like a firm definition of this.

Can any of you help me on this, or point me in the right direction?

 

All and any help will be much appreciated.

 

MED VENLIG HILSEN / BEST REGARDS
 
Bjarne Büchmann, PhD

Forsvarsministeriets Materiel- og Indkøbsstyrelse

Danish Ministry of Defence Acquisition and Logistics Organization
Joint GEOMETOC Support Centre

Lautrupbjerg 1-5 - DK-2750 Ballerup

TLF.   +45 72 81 56 24
MOBIL +45 40 78 73 20

 

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[Knut]

Hi Bjarne,

convc is the angle measured clockwise between the geographical axes (true north) and the local coordinate axes (grid north). if not provided, convc=0.

hope this helps?

cheers, knut

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[Bjarne Büchmann]

Hi Knut,

 

Thanks, yes it helps.

Just two quick follow-ups.

Angle should be an degrees (360), right?

For a Cartesian grid, there is no “lat” to point north, so I assume that the y-direction is meant by “north”.

 

So it is the counter-clockwise angle (in degrees) from the (local) y-axis direction to true north.

 

MED VENLIG HILSEN / BEST REGARDS
 
Bjarne Büchmann

Joint GEOMETOC Support Centre

MOBIL +45 40 78 73 20

To view this discussion on the web visit https://groups.google.com/d/msgid/getm-users/a8c6175d-d81b-819a-5bdc-46f967b07872%40gmx.net.

[Knut]

On 10/10/22 14:24, 'Bjarne Büchmann' via GETM-users wrote:

Hi Knut,

 

Thanks, yes it helps.

Just two quick follow-ups.

Angle should be an degrees (360), right?

yes

For a Cartesian grid, there is no “lat” to point north, so I assume that the y-direction is meant by “north”.

yes

 

So it is the counter-clockwise angle (in degrees) from the (local) y-axis direction to true north.

yes

To view this discussion on the web visit https://groups.google.com/d/msgid/getm-users/62b2207ac5544a9e8695bb5606ce98b1%40fcoo.dk.