PUBLIC INTERFACE ~ PUBLIC DATA ~ PUBLIC ROUTINES ~ NAMELIST ~ DIAGNOSTIC FIELDS ~ ERROR MESSAGES ~ REFERENCES ~ NOTES

Module ocean_shortwave_pen_mod

Contact:  A. Rosati John P. Dunne S. M. Griffies Colm Sweeney
Reviewers:  Russell Fiedler
Change History: WebCVS Log


OVERVIEW

This module returns thickness weighted temperature tendency [deg C *m/sec] from penetrative shortwave heating.

Compute thickness weighted tendency [deg C *m/sec] of tracer associated with penetrative shortwave heating in the upper ocean. Generally penetration is taken as a function of monthly optical properties of the upper ocean, where optical properties are read in from a file of climatological data. Presently there is account taken only of chlorophyll-a on the optical properties of ocean water. Other particulates can be added so to have a more complete picture of the ocean optical properties. Also, this module provide a framework for incorporating the effects from a prognostic biology model on ocean optics.


OTHER MODULES USED

          axis_utils_mod
constants_mod
diag_manager_mod
field_manager_mod
fms_mod
mpp_mod
time_interp_external_mod
ocean_domains_mod
ocean_tpm_util_mod
ocean_types_mod

PUBLIC INTERFACE

ocean_shortwave_pen_init:
sw_source:
sw_pen:


PUBLIC DATA

None.


PUBLIC ROUTINES

  1. ocean_shortwave_pen_init

    DESCRIPTION
    Initialization for the shorwave module


  2. sw_source

    DESCRIPTION
    Incorporate short wave penetration via the "source" term. note that the divergence of shortwave for the first level "div_sw(0)" is compensating for the effect of having the shortwave component already included in the total surface tracer flux "stf(i,j,temp)"

    output:

    tracer_source = thickness weighted source from penetrative short wave heating



  3. sw_pen

    DESCRIPTION
    Solar shortwave energy penetrates below the ocean surface and is aborbed by water and organic matter (both particulate and dissolved). This routine estimates fraction of shortwave penetration using chlorophyll a. Absorbtion of shortwave radiation in the water assumes energy partitions between three exponentials:

    The first exponential is for wavelength > 0.75 um (microns) and assumes a single attenuation of 0.267 m if the "zenith_angle" is 0. Presently the code assumes a zero zenith angle, but this could be modified easily.

    The second and third exponentials represent a parameterization of the attenuation coeficient for light between 300 um and 750 um in the following form:

    E(z) = E(0) * [V1 * exp(z/efold1) + V2 * exp(z/efold2)] with z < 0 the ocean depth

    Here, V1+V2=1 represent the partitioning between long (V1) and short (V2) wavelengths between 300 um and 750 um. Thoughout most of the ocean V1<0.5 and V2>0.5. The "efold1" and "efold2" are the efolding depth of the long and short visable and ultra violet light. Throughout most of the ocean efold1 should not exceed 3 m while the efold2 will vary between 30 m in oligotrophic waters and 4 m in coastal regions. All of these constants are based on satellite estimates of chlorophyll a and taken from Morel and Antoine (JPO 1994, (24) 1652-1664).

    If the thickness of the first ocean level "dzt(1)" is 50 meters, then shortwave penetration does not do much. However, for higher vertical resolution, such as dzt(1) = 10 meters commonly used in ocean climate models, the effect of shortwave heating can be significant. This can be particularly noticable in the summer hemisphere.




NAMELIST

&ocean_shortwave_pen_nml

shortwave_pen_on=
Must be .true. to run with module.
[logical]
read_chl
If .true. then read in climatological data of chlorophyll-a.
[logical]
sw_frac_top
The fraction of shortwave radiation that should be incorporated into the sw_source array at k=1. The generic treatment in mom4 is to assume that shortwave radiation is already contained inside the T_prog(index_temp)%stf field. Hence, to avoid double counting, sw_frac(k=0)=sw_frac_top should=0.0. If one removes shortwave from stf, then set sw_frac_top=1.0.
[real]
zmax_pen
Maximum depth of penetration of shortwave radiation. Below this depth, shortwave penetration is exponentially small and so is ignored.
[real, units: meter]
chl_default
Default concentration chl_default=0.08 roughly yields Jerlov Type 1A optics.
[real, units: mg/m^3]
enforce_sw_frac
To ensure the shortwave fraction is monotonically decreasing with depth.
[logical]
debug_sw_pen
For debugging purposes.
[logical]


DATA SETS

None.


ERROR MESSAGES

None.


REFERENCES

  1. Jerlov (1968) Optical Oceanography Elsevier Press
  2. Morel and Antoine (1994) Heating rate in the upper ocean in relation to its bio-optical state Journal of Physical Oceanography vol 24 pages 1652-1664
  3. Paulson and Simpson (1977) Irradiance measurements in the upper ocean Journal of Physical Oceanography vol 7 pages 952-956
  4. Rosati and Miyakoda (1988) A General Circulation Model for Upper Ocean Simulation Journal of Physical Oceanography vol 18 pages 1601-1626.


COMPILER SPECIFICS

None.


PRECOMPILER OPTIONS

None.


LOADER OPTIONS

None.


TEST PROGRAM

None.


KNOWN BUGS

None.


NOTES

Optimized for vector peformance by R. Fiedler (russell.fiedler@csiro.au) June 2003 on the Australian NEC computer.


FUTURE PLANS

None.


top