geog.tcl
and
land.tcl.
Note that
geog.tcl
also defines
Geographic Procedures.
div_wind(u,v)
and
vorticity_wind(u,v)
gives the divergence (/second) and vorticity (/second) of a 2D wind, where
Let q be latitude in radians, j be longitude in radians, r be radius of earth in metres.
The divergence of a 2D wind is defined as
¶u/¶x +
¶v/¶y
Function
div_wind
uses the equivalent formula
(¶u/¶j +
¶(v
cos q)/¶q) /
(r cos q)
The vorticity of a 2D wind is defined as
¶v/¶x -
¶u/¶y
Function
vorticity_wind
uses the equivalent formula
(¶v/¶j -
¶(u
cos q)/¶q) /
(r cos q)
is_land(latitude,
longitude[,
data_dir])
i8
(8-bit signed integer) matrix with 1 for land and 0 for sea.
The data has an accuracy of 0.01°.
The arguments latitude and longitude can be scalars, vectors or matrices. If they are either both vectors, or one is a vector and the other is a scalar, then they are used as the coordinate variables of the matrix result. Otherwise the result has the same shape and coordinate variables as the one of higher rank.
The optional argument data_dir is only needed if a non-standard data directory is to be used.
is_coast(latitude,
longitude[,
data_dir])
i8
(8-bit signed integer) matrix with 1 for coast and 0 otherwise.
The data has an accuracy of 0.01°.
The arguments latitude and longitude are vectors. These are used to define the coordinate variables of the result.
The optional argument data_dir is only needed if a non-standard data directory is to be used.
area_on_globe(latitude, longitude)
Example:
% [nap "area_on_globe(-90 .. 0 ... 45, 0 .. 180 ... 45)"] value -format %.4f
0.0229 0.0092 0.0092 0.0092 0.0229
0.0781 0.0312 0.0312 0.0312 0.0781
0.2115 0.0846 0.0846 0.0846 0.2115
fix_longitude(longitude)
degrees_east.
merid_wt(longitude)
Example:
% [nap "merid_wt {-180 -90 -45 0 90 180}"]
0.125 0.1875 0.125 0.1875 0.25 0.125
zone_wt(latitude)
Example:
% [nap "zone_wt(-90 .. 90 ... 30)"] value
0.0334936 0.125 0.216506 0.25 0.216506 0.125 0.0334936
acof2boxed(filename)
Example:
nap "in = acof2boxed('abc.acof')"
get_gridascii(filename)
Example:
% nap "in = get_gridascii('abc.gridascii')"