From 63442dc0ba9b734d80471068fadf15757a631fbf Mon Sep 17 00:00:00 2001
From: Dave Gill <gill@ucar.edu>
Date: Mon, 1 Oct 2018 09:10:36 -0600
Subject: [PATCH] TYPE: bugfix

KEYWORDS: Noah-MP

SOURCE: Michael Barlage (NCAR)

DESCRIPTION OF CHANGES:

Bug fix introduced in #399 where divide by zero can occur if LAI is zero. Added check in IF statement. This calculation is only for diagnostics so shouldn't change answers, except to prevent model crash.

LIST OF MODIFIED FILES:

M phys/module_sf_noahmpdrv.F

TESTS CONDUCTED:

Summer and winter 24-hr case
---
 phys/module_sf_noahmpdrv.F | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/phys/module_sf_noahmpdrv.F b/phys/module_sf_noahmpdrv.F
index 53226c103d..9c986d9ad2 100644
--- a/phys/module_sf_noahmpdrv.F
+++ b/phys/module_sf_noahmpdrv.F
@@ -979,7 +979,7 @@ SUBROUTINE noahmplsm(ITIMESTEP,        YR,   JULIAN,   COSZIN,XLAT,XLONG, & ! IN
              RB                            = MAX(RB, 0.0)
 ! New Calculation of total Canopy/Stomatal Conductance Based on Bonan et al. (2011) 
 ! -- Inverse of Canopy Resistance (below)
-             IF(RSSUN .le. 0.0 .and. RSSHA .le. 0.0) THEN
+             IF(RSSUN .le. 0.0 .or. RSSHA .le. 0.0 .or. LAISUN .eq. 0.0 .or. LAISHA .eq. 0.0) THEN
                 RS    (I,J)                = 0.0
              ELSE
                 RS    (I,J)                = ((1.0/(RSSUN+RB)*LAISUN) + ((1.0/(RSSHA+RB))*LAISHA))