Merge #317

317: Address edge cases in cloud sampling r=szy21 a=szy21 When comparing random number with 1 - cloud fraction, we change the condition > to >= to address the edge case that cloud fraction is 1 but random number is 0. Co-authored-by: Zhaoyi Shen <[email protected]>
CliMA · Sep 20, 2022 · 27ebc3c · 27ebc3c
2 parents 6d5bacd + 90855a3
commit 27ebc3c
Showing 1 changed file with 4 additions and 2 deletions.
diff --git a/src/optics/CloudOptics.jl b/src/optics/CloudOptics.jl
@@ -243,8 +243,9 @@ function build_cloud_mask!(cld_mask, cld_frac, random_arr, gcol, ::MaxRandomOver
         end
         # set cloud mask for cloudy layers
         # last layer
+        # RRTMG uses local_rand[igpt, finish] > (FT(1) - local_cld_frac[finish]), we change > to >= to address edge cases
         for igpt in 1:ngpt
-            local_cld_mask[igpt, finish] = local_rand[igpt, finish] > (FT(1) - local_cld_frac[finish])
+            local_cld_mask[igpt, finish] = local_rand[igpt, finish] >= (FT(1) - local_cld_frac[finish])
         end
         for ilay in (finish - 1):-1:start
             if local_cld_frac[ilay] > FT(0)
@@ -254,7 +255,8 @@ function build_cloud_mask!(cld_mask, cld_frac, random_arr, gcol, ::MaxRandomOver
                     else
                         local_rand[igpt, ilay] *= (FT(1) - local_cld_frac[ilay + 1]) # update random numbers if layer above is not cloudy
                     end
-                    local_cld_mask[igpt, ilay] = local_rand[igpt, ilay] > (FT(1) - local_cld_frac[ilay])
+                    # RRTMG uses local_rand[igpt, ilay] > (FT(1) - local_cld_frac[ilay]), we change > to >= to address edge cases
+                    local_cld_mask[igpt, ilay] = local_rand[igpt, ilay] >= (FT(1) - local_cld_frac[ilay])
                 end
             else
                 for igpt in 1:ngpt