[MITgcm-support] External forcing - runoff

Menemenlis, Dimitris (3248) Dimitris.Menemenlis at jpl.nasa.gov
Sat Aug 10 06:38:31 EDT 2013


The format of specifying the longitude and the latitude is different:
      _RL runoff_lon0, runoff_lon_inc
      _RL runoff_lat0, runoff_lat_inc(MAX_LAT_INC)

That is, runoff_lon_inc is a constant while
runoff_lat_inc is a vector.
This is so as to allow uneven increments in latitude, e.g., a Gaussian grid.

For 1/4-degree grid, you could have, e.g.:
 runoff_lon0       = 0.125D0,
 runoff_lon_inc    = 0.25D0,
 runoff_lat0       = -89.875D0,
 runoff_lat_inc    = 719*0.25D0,

You can also specify runoff on the full model grid by setting variable:
  runoff_interpMethod = 0,

On Aug 9, 2013, at 8:39 PM, Jonathan Whitefield wrote:

> I'm working on a model run with a higher resolution forcing for river
> runoff, and I'm trying to understand some of the lines in data.exf:
> 
> runoff_lon0       = 0.50D0,
> runoff_lon_inc    = 1.0D0,
> runoff_lat0       = -89.5D0,
> runoff_lat_inc    = 179*1.,
> 
> I get the first two lines - the first longitude box is at 0.5 degrees,
> and each subsequent box is 1 degree more. It's the same as Matlab
> saying lon=0.5:1:359.5. The third line I'm also fine with - the
> latitude starts at -89.5. However, I don't get the last line. The
> increase between cells is a different format to lon_inc. Is this
> because lat is vertical, and it should be a column of 179 "1"s? Why is
> it not just 1.0D0 as for lon_inc?
> 
> If I wanted to do a quarter degree resolution, should I have
> runoff_lat_inc = 1439*0.25?
> 
> Thanks again.
> 
> -- 
> Jonathan Whitefield, M.Sc.
> Ph.D. Student, Physical Oceanography
> 
> 110 O'Neill Building,
> P.O. Box 757220
> University of Alaska Fairbanks
> Fairbanks, AK 99775-7220
> 
> Phone: (907) 474-5184
> Fax: (907) 474-5863
> 
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