Further bug fixes on read_radar.f90 and stpcalc.f90

    1. The deter_zsfc_model and deter_sfc2 in read_radar_l2rw subroutine should still be used. Otherwise the uninitialized skint and zsges may cause issue in debug mode.
    2. The logic of L840-865 in stpcalc.f90 is supposed to find the historical minimum outpen looping i from 1 to nsteptot, where nsteptot can be greater than istp_iter (the maximum possible is 3*istp_iter+1 depend on how many times it tried to search).
      When it stored the minimum outpen stepsize at L846:
              stp(ii)=outstp(i)
      It used ii, which is istp_iter according to the if statement at L840.
      Then the istp_use at L848 should also be ii for consistency, otherwise it may exceed the array in debug mode.
      The if statement at L851 should use nsteptot instead of istp_iter as well.
From @XuLu-NOAA

src/gsi/read_radar.f90

@@ -4233,11 +4233,10 @@ subroutine read_radar_l2rw(ndata,nodata,lunout,obstype,sis,nobs,hgtl_full)
             rusage(ndata)=.false.
             usage=r100
           end if
-          call deter_zsfc_model(dlat,dlon,zsges)
 
 !    Get information from surface file necessary for conventional data here
-!         call deter_zsfc_model(dlat,dlon,zsges)
-!         call deter_sfc2(dlat_earth,dlon_earth,t4dv,idomsfc,skint,ff10,sfcr)
+          call deter_zsfc_model(dlat,dlon,zsges)
+          call deter_sfc2(dlat_earth,dlon_earth,t4dvo,idomsfc,skint,ff10,sfcr)
 
           nsuper2_kept=nsuper2_kept+1
           cdata(1) = error             ! wind obs error (m/s)

src/gsi/stpcalc.f90

@@ -844,10 +844,10 @@ subroutine stpcalc(stpinout,sval,sbias,dirx,dval,dbias, &
            if(outpen(i) < outpensave)then
               stp(ii)=outstp(i)
               outpensave=outpen(i)
-              istp_use=i
+              istp_use=ii
            end if
         end do
-        if(istp_use /= istp_iter) then
+        if(istp_use /= nsteptot) then
            final_ii=ii
            exit stepsize
         end if