Double Gyre

This is the example of a double-gyre wind-driven circulation in a rectangular basin of size 3672 km x 2754 km. To run this code properly you need to:

Modify subroutine winds.F to set the winds analytically instead of reading it from a file. The steps are the following:
1. Change the name of the subroutine Set_Wind to Set_Wind_Bogus (or just comment it out).
2. Change the name of the subroutine Set_Wind_Dgyre to Set_Wind
3. In file setups.F: comment the call to Read_Winds, and uncomment the call to Set_Wind.
Copy the Sflags.h and dimns.F90 files to the src directory.
Change the Makefile to compile shallow with the initialization file trest.F. This way the simulation starts from a state of rest.
Build the executable.
run the code:
```
 shallow  < dgyre.in 
```

This code was used to test the filtering strategy devised by Julia Levin et al. I have commented out the FILTER flag in Sflags.h. If filtering is desired, the flag can be turned on again. Currently it is set to filter every 6 steps of the simulation.

Configuration files for double gyre problem:
- Physical parameter setting for "shallow" dgyre.txt
- Input list of files for "shallow" dgyre.in
- CPP flags for "shallow" Sflags.h
- dimension file for "shallow" dimns.F90
- Pressure grid file fow "shallow" xygrid.p
- Velocity grid file fow "shallow" xygrid.v
Postprocessing scripts
- Contour drawing matlab script pcont.m to visualize interface contours
- Contour drawing NCAR script for "contours" to visualize interface elevation zeta.com
- Grid drawing NCAR script for "drawcoast" grid.com