To calculate integrated shortwave or longwave irradiance, or to simulate
satellite instrument channels, use
mol_abs_param type
to choose between the following types of correlated-k schemes:
- kato
-
Kato1999b correlated-k distribution, shortwave; based on HITRAN 96. Please note that the bands above 2.5 micrometer are not very reliable which, however, this has only little impact on integrated shortwave radiation.
- kato2
-
Kato1999b, shortwave; optimized version (Seiji Kato, personal communication, 2003); please note that kato2 only has 148 subbands (that is, calls to the rte_solver) compared to 575 for kato which translates to a increase in computational speed by up to a factor of 4 with only little increase in uncertainty. The absorption data are based on HITRAN 2000. Please note that the bands above 2.5 micrometer are not very reliable which, however, this has only little impact on integrated shortwave radiation.
- kato2.96
-
Kato1999b, shortwave; optimized version (Seiji Kato, personal communication, 2003); similar to kato2 but based on HITRAN96. Please note that the bands above 2.5 micrometer are not very reliable which, however, has only little impact on integrated shortwave radiation.
- fu
-
fu92,fu93, shortwave and longwave; fast parameterization, developed for climate models.
- avhrr_kratz
-
Kratz1995, AVHRR instrument channels
- lowtran
-
Gas absorption parameterization from LOWTRAN; code adopted from SBDART Ricchiazzi1998b; please see the section on ”Spectral resolution”.
- sbdart
-
Identical to LOWTRAN.
- repwvl
-
Representative wavelengths parameterization Buehler2010 adapted for spectral bands. Different band widths may be selected by
mol_abs_param repwvl [fine|medium|coarse]
(fine: 1cm; medium: 5cm
; coarse: 15cm
; default: coarse). The data files are provided at the libRadtran homepage. Absorption data are based on HITRAN 2004. Absorption by H2O, CO2, O3, N2O, CO, CH4, O2, and N2 is considered, and absorption by all other gases is zero. By default volume mixing ratios of N2O, CO, CH4, and N2 (those are not in the atmosphere_file) from the US standard atmosphere are applied. Use mol_file or mol_modify to change the profiles. In case of radiative transfer problems with solar source, the extraterrestrial spectrum from Kurudz is applied by default.
- repwvl_channel
-
Representative wavelengths parameterization Buehler2010 for satellite channels. Usage
mol_abs_param repwvl_channel channel_name
Channel-integrated quantities are obtained using output per_ck_band. The file data/correlated_k/repwvl/channel_list.txt provides a list of available channels; more information on the channels is provided in data/filter/.
If mol_abs_param kato/kato2/kato2.96/fu/avhrr_kratz is specified, the extraterrestrial flux is taken from internally defined files specific for each parameterization, not from source solar file. The output is the integrated irradiance for each band. To get e.g. integrated shortwave irradiance, simply add all bands of the Kato1999b or the fu92,fu93 parameterization. The five AVHRR channels are weighted sums of the libRadtran output. Examples how to integrate the output in the avhrr_kratz case are included in the uvspec self check which is initiated with make check.