diff --git a/src/core_atmosphere/physics/mpas_atmphys_driver_radiation_sw.F b/src/core_atmosphere/physics/mpas_atmphys_driver_radiation_sw.F
index f4b76d8fe8..ee40d407d8 100644
--- a/src/core_atmosphere/physics/mpas_atmphys_driver_radiation_sw.F
+++ b/src/core_atmosphere/physics/mpas_atmphys_driver_radiation_sw.F
@@ -792,6 +792,7 @@ subroutine driver_radiation_sw(itimestep,configs,mesh,state,time_lev,diag_physic
               swdnt      = swdnt_p      , swdntc     = swdntc_p      , swupb    = swupb_p  , &
               swupbc     = swupbc_p     , swdnb      = swdnb_p       , swdnbc   = swdnbc_p , &
               swddir     = swddir_p     , swddni     = swddni_p      , swddif   = swddif_p , &
+              julian     = curr_julday  ,                                                    &
               ids = ids , ide = ide , jds = jds , jde = jde , kds = kds , kde = kde ,        &
               ims = ims , ime = ime , jms = jms , jme = jme , kms = kms , kme = kme ,        &
               its = its , ite = ite , jts = jts , jte = jte , kts = kts , kte = kte          &
diff --git a/src/core_atmosphere/physics/physics_wrf/module_ra_rrtmg_sw.F b/src/core_atmosphere/physics/physics_wrf/module_ra_rrtmg_sw.F
index be36c4afb1..55f57e9161 100644
--- a/src/core_atmosphere/physics/physics_wrf/module_ra_rrtmg_sw.F
+++ b/src/core_atmosphere/physics/physics_wrf/module_ra_rrtmg_sw.F
@@ -9876,7 +9876,7 @@ subroutine rrtmg_swrad( &
                        swupt,swuptc,swdnt,swdntc,                      &
                        swupb,swupbc,swdnb,swdnbc,                      &
                        swupflx, swupflxc, swdnflx, swdnflxc,           &
-                       swddir,swddni,swddif,                           &
+                       swddir,swddni,swddif,julian,                    &
                        ids,ide, jds,jde, kds,kde,                      & 
                        ims,ime, jms,jme, kms,kme,                      &
                        its,ite, jts,jte, kts,kte                       &
@@ -9893,6 +9893,7 @@ subroutine rrtmg_swrad( &
  integer,intent(in):: icloud,has_reqc,has_reqi,has_reqs
  integer,intent(in):: julday
  integer,intent(in),optional:: o3input
+ real,intent(in):: julian
 
  real,intent(in):: radt,degrad,xtime,declin,solcon,gmt
  real,intent(in),dimension(ims:ime,jms:jme):: xlat,xlong
@@ -9933,6 +9934,7 @@ subroutine rrtmg_swrad( &
  integer:: i,j,k,n
 
  real:: coszrs,xt24,tloctm,hrang,xxlat,adjes,scon
+ real:: da,eot
  real:: ro,dz
  real:: corr
  real:: gliqwp,gicewp,gsnowp,gravmks
@@ -10022,9 +10024,14 @@ subroutine rrtmg_swrad( &
 
        !--- calculate the cosine of the solar zenith angle at the current time step to determine if the sun is
        !    above or below the horizon (xt24 is the fractional part of simulation days plus half of radt in 
-       !    units of minutes, julian is in days, and radt is in minutes). do not call rrtmg_sw is night-time:
+       !    units of minutes, julian is in days, and radt is in minutes). eot (equation of time) is a correction
+       !    of mean solar time due to the difference between that time and the apparent solar time. 
+       !    do not call rrtmg_sw is night-time:
        dorrsw = .true.
-       xt24 = mod(xtime+radt*0.5,1440.)
+       da=6.2831853071795862*(julian-1.)/365.
+       eot=(0.000075+0.001868*cos(da)-0.032077*sin(da) &
+            -0.014615*cos(2*da)-0.04089*sin(2*da))*(229.18)
+       xt24 = mod(xtime+radt*0.5,1440.)+eot
        tloctm = gmt + xt24/60. + xlong(i,j)/15.
        hrang = 15. * (tloctm-12.) * degrad
        xxlat = xlat(i,j) * degrad