Module ocean_shortwave_pen_mod
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
PUBLIC DATA
None.
PUBLIC ROUTINES
-
ocean_shortwave_pen_init
-
DESCRIPTION
- Initialization for the shorwave module
-
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
-
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
- Jerlov (1968)
Optical Oceanography
Elsevier Press
- 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
- Paulson and Simpson (1977)
Irradiance measurements in the upper ocean
Journal of Physical Oceanography vol 7 pages 952-956
- 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.