t_90 :: (real ~ "1" on
         (i = 1 .. nlon + 1 by j = 1 .. nlat by k = 1 .. nlev)
        )


CSE Eliminated

t_90 := ( varidx(t_102, [i, j, k])
        * ( varidx(T, [i, j, k]) * (1 - varidx(q, [i, j, k]))
          + varidx(T, [i - 1, j, k]) * (1 - varidx(q, [i - 1, j, k]))
          )
        )