diff --git a/CHANGELOG.md b/CHANGELOG.md
index e6762dc2..8874a28b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -32,6 +32,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   when in data_driven mode
 - typo in filepath for BR optics file
 
+- set hsurf to be the last indexed layer when index domains are different
+
 ### Added
 
 ## [v2.4.3] - 2025-07-21
diff --git a/Process_Library/GOCART2G_Process.F90 b/Process_Library/GOCART2G_Process.F90
index b99174ae..9a4d56e1 100644
--- a/Process_Library/GOCART2G_Process.F90
+++ b/Process_Library/GOCART2G_Process.F90
@@ -1521,7 +1521,8 @@ subroutine Chem_SettlingSimple ( km, klid, mie, bin, cdt, grav, &
 
    ONE_OVER_G = 1.0/grav
 
-   hsurf => hghte(i1:i2,j1:j2,km)
+   dk = ubound(hghte,3)
+   hsurf => hghte(i1:i2,j1:j2,dk)
 
    allocate(dz(i2,j2,km), radius(i2,j2,km), rhop(i2,j2,km), vsettle(i2,j2,km), qa(i2,j2,km), source=0.0)
    allocate(cmass_before(i2,j2), cmass_after(i2,j2), source=0.0_DP)
@@ -1706,7 +1707,8 @@ subroutine Chem_Settling ( km, klid, bin, flag, cdt, grav, &
 
    ONE_OVER_G = 1.0/grav
 
-   hsurf => hghte(i1:i2,j1:j2,km)
+   dk = ubound(hghte,3)
+   hsurf => hghte(i1:i2,j1:j2, dk)
 
    allocate(dz(i2,j2,km), radius(i2,j2,km), rhop(i2,j2,km), vsettle(i2,j2,km), qa(i2,j2,km), source=0.0)
    allocate(cmass_before(i2,j2), cmass_after(i2,j2), source=0.0_DP)
@@ -2440,7 +2442,8 @@ subroutine Chem_Settling2Gorig (km, klid, flag, bin, int_qa, grav, delp, &
 
    gravDP = grav
 
-   hsurf => hghte(i1:i2,j1:j2,km)
+   dk = ubound(hghte,3)
+   hsurf => hghte(i1:i2,j1:j2, dk)
 
 !  Allocate arrays
 !  ---------------
@@ -2783,7 +2786,8 @@ subroutine Chem_SettlingSimpleOrig ( km, klid, flag, grav, cdt, radiusInp, rhopI
    i2 = ubound(hghte,1)
    j2 = ubound(hghte,2)
 
-   hsurf => hghte(i1:i2,j1:j2,km)
+   dk = ubound(hghte,3)
+   hsurf => hghte(i1:i2,j1:j2, dk)
 
 !  Allocate arrays
 !  ---------------
@@ -6524,7 +6528,8 @@ subroutine SulfateDistributeEmissions ( km, nbins, cdt, grav, nymd, nhms, &
    i2 = size(rhoa,1)
    j2 = size(rhoa,2)
    allocate(hsurf(i1:i2,j1:j2))
-   hsurf = hghte(i1:i2,j1:j2,km)
+   k  = ubound(hghte,3) 
+   hsurf = hghte(i1:i2,j1:j2,k)
 
    allocate(srcSO2(i2,j2), srcSO4(i2,j2), srcDMS(i2,j2), srcSO4anthro(i2,j2), &
             srcSO2anthro(i2,j2), srcSO2bioburn(i2,j2), source=0.0)