half_resolution

DESCRIPTION

The subroutine "half_resolution" produces an output field with half the resolution of the input field. The half resolution field may cover the full domain of the original field, or a subdomain. The algorithm used ensures that all original nodes are assigned with equal weight, with the exception of those that are next to undefined (dry) nodes or the edges. The subroutine may be called twice to produce one quarter resolution output etc. Remember to reset 'new_map' to '.true.' everytime a new land-sea grid is used, e.g., when an original half resolution output is processed to a quarter resolution product.

SYNTAX

subroutine

half_resolution

( nx_in,ny_in,field_in,x0,y0,xN,yN,new_map,map_factor,defined_node, nx_out,ny_out,field_out )

INPUT, OUTPUT VARIABLES

Input:

nx_in, ny_in	(i)	-	dimension of the fine mesh (original) domain, used for 'field_in(,)'
field_in	(RR)	-	the original fine mesh field
x0,y0	(i)	-	fine mesh coordinates of the lower left corner of the subdomain to consider
xN,yN	(i)	-	fine mesh coordinates of the upper right corner of the subdomain to consider
new_map	(l)	-	should be set to 'true.' when 'map_factor(,,)' must be set (or reset), i.e., when a new land-sea grid is encounted.
nx_out, ny_out	(i)	-	dimension of the coarse mesh (output) domain, used for 'field_out(,)', 'map_factors(,,)' and 'defined_node(,)'

Input/output:

map_factor	(RRR)	-	facors that will be used in the calculation of the coarse grid field, set when 'new_map' is '.true.', should not be modified outside this subroutine
defined_node	(LL)	-	specification of coarse mesh land-sea grid, set when 'new_map' is '.true.', should not be modified outside this subroutine

Output:

field_out

(RR)

-

the coarse mesh output field

DEPENDENCIES

External: none
Internal: functions get_value, get_edge_x, get_edge_y

EXAMPLE

Input:
nx_in = ny_in = 8 (4 in "second iteration")
field_in(x,y) = x*y
x0 = y0 = 1
xN = yN = 8 (4)
new_map = .true.
nx_out = ny_out = 4 (2)


 Original field ['field_in(,)']:
   8.0  16.0  24.0  32.0  40.0  48.0  56.0  64.0
   7.0  14.0  21.0  28.0  35.0  42.0  49.0  56.0
   6.0  12.0  18.0  24.0  30.0  36.0  42.0  48.0
   5.0  10.0  15.0  20.0  25.0  30.0  35.0  40.0
   4.0   8.0  12.0  16.0  20.0  24.0  28.0  32.0
   3.0   6.0   9.0  12.0  15.0  18.0  21.0  24.0
   2.0   4.0   6.0   8.0  10.0  12.0  14.0  16.0
   1.0   2.0   3.0   4.0   5.0   6.0   7.0   8.0

Output I:

Half resolution field ("first iteration"):
    -   15.3    -   30.7    -   46.0    -   58.8
    -     -     -     -     -     -     -     -
    -   12.0    -   24.0    -   36.0    -   46.0
    -     -     -     -     -     -     -     -
    -    8.0    -   16.0    -   24.0    -   30.7
    -     -     -     -     -     -     -     -
    -    4.0    -    8.0    -   12.0    -   15.3
    -     -     -     -     -     -     -     -

Output II:

Quarter resolution field ("second iteration"):
    -     -     -   28.4    -     -     -   50.6
    -     -     -     -     -     -     -     -
    -     -     -     -     -     -     -     -
    -     -     -     -     -     -     -     -
    -     -     -   16.0    -     -     -   28.4
    -     -     -     -     -     -     -     -
    -     -     -     -     -     -     -     -
    -     -     -     -     -     -     -     -