Add unit test for routine get_xnsum2.

Fixes ufs-community#1000.

tests/orog/CMakeLists.txt

@@ -45,3 +45,7 @@ target_link_libraries(ftst_find_nearest_pole_pts orog_lib)
 add_executable(ftst_get_xnsum ftst_get_xnsum.F90)
 add_test(NAME orog-ftst_get_xnsum COMMAND ftst_get_xnsum)
 target_link_libraries(ftst_get_xnsum orog_lib)
+
+add_executable(ftst_get_xnsum2 ftst_get_xnsum2.F90)
+add_test(NAME orog-ftst_get_xnsum2 COMMAND ftst_get_xnsum2)
+target_link_libraries(ftst_get_xnsum2 orog_lib)

tests/orog/ftst_get_xnsum2.F90

@@ -0,0 +1,72 @@
+ program check_get_xnsum2
+
+! Unit test for routine get_xnsum2, which counts the
+! number of high-resolution orography points within a
+! model grid box, and counts the number of high-resolution
+! points higher than a critical height. The critical
+! height is a function of the standard deviation of height.
+
+ use orog_utils, only : get_xnsum2
+
+ implicit none
+
+ integer, parameter :: imn=360  ! i-dimension of high-res grid
+ integer, parameter :: jmn=181  ! j-dimension of high-res grid
+
+ integer            :: j
+ integer            :: zavg(imn,jmn)  ! High-res grid terrain
+
+ real               :: delxn=360.0/float(imn) ! Resolution of high-res grid in degrees.
+ real               :: glat(jmn)              ! Latitude of each high-res grid row in degrees.
+ real               :: lon1,lat1,lon2,lat2,hc
+ real               :: xnsum1,xnsum2
+
+! Variables holding the expected test results.
+
+ real, parameter    :: EPSILON=0.001
+ real               :: expected_hc
+ integer            :: expected_xnsum1, expected_xnsum2
+
+ data expected_hc /677.2/   ! Expected critical height in meters.
+ data expected_xnsum1 /8/   ! Expected number of high-res pts in model
+                            ! grid box that are above the critical height.
+ data expected_xnsum2 /16/  ! Expected total number of high-res pts in model grid box.
+
+ print*,"Begin test of routine get_xnsum2."
+
+! The high-res grid is a global one-degree lat/lon grid. Point (1,1)
+! is the south pole/greenwich.
+
+ do j = 1, jmn
+   glat(j) = -90.0 + float(j-1) * delxn
+ enddo
+
+! Bounds of model grid box - straddles equator/greenwich.
+! There are 16 high-res points located within the model
+! box. The i/j range of these 16 points is i=359,360,1,2
+! and j=0,91,92,93.
+
+ lon1 = -2.5  ! in degrees.
+ lon2 = 2.5
+ lat1 = -1.5
+ lat2 = 1.5
+
+! Initialize high-res orography. Half of the points
+! within the model grid box are at sea level and the
+! other half at 1000 meters.
+
+ zavg = -999  ! Flag value for sea level.
+ zavg(359:360,90:93) = 1000
+
+ call get_xnsum2(lon1,lat1,lon2,lat2,imn,jmn, &
+                 glat,zavg,delxn,xnsum1,xnsum2,hc)
+
+ if (nint(xnsum1) /= expected_xnsum1) stop 2
+ if (nint(xnsum2) /= expected_xnsum2) stop 4
+ if (abs(hc-expected_hc) > EPSILON) stop 6
+
+ print*,"OK"
+
+ print*,"SUCCESS"
+
+ end program check_get_xnsum2