------------------------------------------------------------
Changes from Noah-MP v1.0 to v1.1 (August 2012)
------------------------------------------------------------

    Remember snow aging term (TAUSS) from one timestep to the next.
    The TAUSS term becomes a registry variable in WRF.  Changes to
    subroutine SNOW_AGE and add TAUSS to the argument lists of all the
    subroutines throughout module_sf_noahmplsm leading to SNOW_AGE.

    Consider urban points as non-vegetated, until we are sure we can
    properly treat low-vegetation-fraction regions.  This requires
    passing ISURBAN to subroutine PHENOLOGY and CARBON, where LAI (and
    others) are set for non-vegetated points, and the main NOAHMP_SFLX
    routine where FVEG is set to zero for non-vegetated points.

    Fix some error threshold checks to test on the absolute value of
    the error, where we had earlier only tested for positive errors.
    Subroutine ERROR.

    Replace a test on zero (to prevent division by zero) with a test
    on a non-zero epsilon.  Subroutine TWOSTREAM.

    Set some default values for vegetation-related terms over
    non-vegetated points.  Subroutine ENERGY.

    Modify vegetation density as a function of the vegetation fraction
    and the canopy crown radius.  Subroutine TWOSTREAM.

    Apply FVEG scaling of radiation terms at appropriate places when
    computing radiation fluxes.  Subroutines ERROR, ENERGY, VEGE_FLUX.

    Improved computation of 2m terms.  Subroutines VEGE_FLUX,
    BARE_FLUX.