Version: v1.0
Date: August 4, 1999
Contact: Bruce Wyman
Returns zonal (London) cloud amount and location (level) on
the model grid for high, middle, and low clouds.
This module interpolates in space and time the zonal mean, seasonally
varying cloud amounts for the given model grid (lat/pres) and time.
time_manager_mod
time_interp_mod
utilities_mod
use cloud_zonal_mod [, only: cloud_zonal_init, cloud_zonal, getcld ]
cloud_zonal_init - Initialization routine that is called once.
The default behavior is for seasonally varying
clouds. To specify clouds that do not vary in
time this routine must be called with a particular
season. There is no option for annual mean clouds.
cloud_zonal - Returns the zonal cloud amounts, location (model level),
and cloud properties on the model grid at the specified time.
getcld - Returns only the zonal cloud amounts and location (model level)
on the model grid at the specified time.
call cloud_zonal_init (season)
Input
season Season for returned data. [integer]
The following are valid values:
1 = winter
2 = spring
3 = summer
4 = fall
5 = seasonal varying
Note: This routine does not need to called. If this routine was not called
previously, then routine getcld (and cloud_zonal) will call it with
seasonal varying clouds (season=5).
-----------------------------------------------------------------------
subroutine cloud_zonal (time, lat, phalf, &
nclds, ktopsw, kbtmsw, ktoplw, kbtmlw, &
cldamt, cuvrf, cirrf, cirab, emcld)
Input
time The current time. Used only when seasonal varying clouds
(season=5) have been initialized. [time_type]
lat The (mean) latitude in radians of all grid boxes.
[real, dimension(:,:)]
phalf Pressure in pascals at half model levels. Should be normalized
so that the pressure at level nlev+1 is 101325 pascals, this
will insure that all grid boxes have three cloud levels.
[real, dimension(:,:,nlev+1)]
Output
nclds The number of clouds in a vertical column at each grid box.
This routine will return nclds=3 at all grid points.
[integer, dimension(:,:)]
ktopsw, The top and bottom index (at layer interfaces) for high,
kbtmsw middle, and low clouds for shortwave calculations.
[integer, dimension(:,:,3)]
ktopsw, The top and bottom index (at model levels) for high,
kbtmlw middle, and low clouds for longwave calculations.
[integer, dimension(:,:,3)]
cldamt The fractional cloud amount for high, middle, and low clouds.
[real, dimension(:,:,3)]
cuvrf The fractional amount of ultraviolet radiation reflected for
high, middle, and low clouds. [real, dimension(:,:,3)]
cirrf The fractional amount of infrared radiation reflected for
high, middle, and low clouds. [real, dimension(:,:,3)]
cirab The fractional amount of infrared radiation absorbed for high,
middle, and low clouds. [real, dimension(:,:,3)]
emcld The emissivity for high, middle, and low clouds.
This routine will return emcld=1 for all clouds.
[real, dimension(:,:,3)]
-----------------------------------------------------------------------
subroutine getcld (time, lat, phalf, ktopsw, kbtmsw, cldamt)
Input
time The current time. Used only when seasonal varying clouds
(season=5) have been initialized. [time_type]
lat The (mean) latitude in radians of all grid boxes.
[real, dimension(:,:)]
phalf Pressure in pascals at half model levels. Should be normalized
so that the pressure at level nlev+1 is 101325 pascals, this
will insure that all grid boxes have three cloud levels.
[real, dimension(:,:,nlev+1)]
Output
ktopsw, The top and bottom index (at layer interfaces) for high,
kbtmsw middle, and low clouds for shortwave calculations.
[integer, dimension(:,:,3)]
ktopsw, The top and bottom index (at model levels) for high,
kbtmlw middle, and low clouds for longwave calculations.
[integer, dimension(:,:,3)]
cldamt The fractional cloud amount for high, middle, and low clouds.
[real, dimension(:,:,3)]
The data used for this module is contained internally in the code.
The amount and pressure altitude data for zonal clouds is for every
5 degrees latitude and all four seasons (DJF, etc....) for high,
middle, and low clouds.
Because the original (London) data was not accessible, the data
contained in this module was derived from an 18 level version of
the GFDL Experimental Prediction Group spectral model.
Cloud reflectivity and absorptivity is defined internally as
global mean values for high, middle, and low clouds.
The following table summaries these values:
| uv ref ir ref ir abs
-------+-------------------------------
high | .210 | .210 | .005
mid | .450 | .450 | .020
low | .590 | .590 | .035
No recent changes.
Fatal Errors in cloud_zonal_init
initialization routine can not be called twice
You have attemped to call cloud_zonal_init more than once.
invalid value of season
The value of season must be between 1 and 5.
See the documentation for cloud_zonal_init.
London, J., 1957: A study of the atmospheric heat balance.
Final Report, AFCRC Contract AF19 (122)-165, 99 pp.,
N.Y. Univ.
There are no known bugs.
1) The time interpolation is done linearly bewteen seasons.
2) High clouds are interpolated using the top (interface) pressure
in a model layer. All high clouds are one model layer thick.
3) Middle clouds are interpolated using the average (top+bottom
interface) pressure. All middle clouds are one model layer thick.
4) Low clouds are interpolated using top and bottom (interface)
pressures separately. Low clouds can be more than one model layer thick.
None.