tdot - CLaMS

The package tdot

The package tdot contains a long- and shortwave radiation code based on Morcrette scheme [1] (emissivity approach) and implemented by W. Zhong (w.zhong@ic.ac.uk) and J. Haigh (j.haigh@ic.ac.uk) from Imperial College of Science in London [3]. The code was adjusted for AIX/LINUX and implemented into CLaMS model hierarchy. Using this code, profiles of heating/cooling rates can be determined at all available pressure levels. For the longwave radiation code the input profiles are: temperature, water vapor, ozone and CO2. For the shortwave radiation code only the ozone profile is necessary. Both codes are validated for the cloud-free atmosphere.

The results were compared with a well established line-by-line radiation scheme [2] and agree very well for pressures between 200 and 10 hPa if UKMO temperature profile up to 0.4 hPa are used. Generally, there are some problems with heating rates on the 2 highest pressure levels because the boundary conditions on the upper edge of the atmosphere are not implemented in the Morcrette scheme.

UKMO, ECMWF or another meteorological data can be used as input for the temperature profiles. The concentration profiles of water and ozone can be derived from the 2d-Mainz model, HALOE the ECMWF data or from the combination of these data types. (recommended: water vapor - ECMWF, ozone - HALOE, temperature - ECMWF). For CO2 a constant mixing ratio of 355 ppmv is assumed. The latitude of the input profiles can be redefined by use of the equivalent latitudes.

Compiling

The program can be compiled on different platforms with the makefile stored in the directory tdot:

make add_temp_dot_ukmo
make add_temp_dot_ecmwf
make add_temp_dot_dlr
make add_temp_dot_nilu

The program will be compiled for UKMO (22 levels), ECMWF (21 levels), ECHAM4(DLR) (19 levels) and NILU (28 levels) data, respectively. For any changes in the configuration (e. g. number of pressure leves) change the according file in the directory fastrad.

The configuration file

The options for the execution of the radiation scheme can be set in the configuration file add_temp_dot.inp:

ppassm                ! prefix of your input files (6 characters) 
24                    ! Data every 24/6 hours (0, 6, 18 and 0 UT)
/dat_icg1/rad/test    ! input/output directory
./mainz               ! input for 2d-Profiles
12 27 01 1999         ! Starttime(hh dd mm yyyy) 
12 28 01 1999         ! Endtime(hh dd mm yyyy) > Starttime  
y                     ! eqlat-correction, y/n (run first add_pv_isobar !)
c                     ! c=Ozone from HALOE/ m= M-2d, /s=special case 
m                     ! m-H2O from meteor. data / n - from climatology
P.Konopka             ! user_id

Remarks:

To use the equivalent-latitudes technique you have to run first the program add_pv_isobar in package isentropic. Then, add_temp_dot recalculates the input profiles for latitude $-90\le\phi\le90^{\circ}$ and pressure $1\le p \le 200$ hPa. This method is recommended for calculations in the polar vortex.
As input for ozone and water vapor profiles either HALOE climatology (c - 10 years climatology, s - considered month from the HALOE data (recommended for best description of diabatic descend in the vortex) or the Mainzer 2d model (m) can be used.
For water vapor the meteor. data (ECMWF) can also be used (m, recommended) instead of the climatology (n)

Additional options for the radiation scheme can be found in the configuration file fast.cfg:

355000.0        ! co2  [ppbv]
3               ! ITASK number of gases included into longwave calculation (ITASK=3: CO2, H2O and O3)
0               ! sflag 1: sun at local time, 0: diurnally averaged
0               ! ilflag  1: land surface, 0: else
10.00     196   ! lat(degs) and jday (only for one profile calculations)
12  0  0        ! local time (only for one profile calculations)

Remarks:

With SFLAG=0 diurnally averaged heating/cooling rates are determined which are recommended for trajectory calculations in the polar vortex
ILFLAG controls albedo coefficients
Clouds can be parameterized by use of liquid water content (longwave scheme)

References

[1] J.-J. Morcrette. Radiation and cloud radiative properties in the European Centre for Medium Range Weather Forecasts Forecasting System. J. Geophys. Res., 96:9121--9132, 1991.

[2] K.Shine. Sources and sinks of zonal momentum in the middle atmosphere diagnosed using the diabatic circulation. Q. J. R. Meteorol. Soc., 115:265--292, 1989.

[3] W.Zhong and Haigh J. D. Improved broadband emissivity parameterization for water vapor cooling rate calculations. J. Atmos. Sci., 52:124--138, 1995.