Karine K-distribution Atmospheric Radiation & Infrared Net Exchanges

Download Karine 3.5

This code performs radiative transfer computations in the LW spectral region, for a absorbing, emitting and scattering atmosphere. karine uses the k-distribution spectral model (and the CK hypothesis for inhomogeneities). Radiative transfer results that are computed are: fluxes (upward, downward, net), the radiative budget (average per layer) and its gas-gas, gas-ground and gas-space components, and the Net Exchange Rate matrix. All results are provided for each spectral interval the input data is defined for, and is also spectrally integrated.

Physical model

The inhomogeneous atmosphere is represented as a succession of homogeneous slabs. The temperature profile is taken as linear between layers centres. In each layer, absorption and scattering properties must be provided for the gas mixture (k-distribution data set), for a water cloud, and for aerosols. Reflection by the ground is taken into account.

Numerical method

Karine is based on a Monte-Carlo algorithm. In addition to the possibility to take into account scattering, this method has the advantage to compute a statistical uncertainty over each result; this uncertainty can be interpreted in terms of a numerical error. In this respect, the Monte-Carlo method is considered as a reference method: the numerical uncertainty can be lowered as much as necessary by increasing the number of realisations.

Net Exchange Formalism

The Monte-Carlo algorithm consists in computing the Net Exchange Rate between each couple (i,j) of atmospheric layers (+ ground and space). See figures for examples. This formalism provides a graphical representation of all radiative net exchanges in the atmospheres: dominant and non-dominant terms can be immediately identified, for any given spectral interval.

pne_mls_cs
pne_mls_ac
venus_ner
Matrix of Net Exchange Rates, spectrally integrated over the LW interval (4-100 micrometers) for a standard clear-sky Mid-Latitude Summer atmospheric profile.
Matrix of Net Exchange Rates, spectrally integrated over the LW interval (4-100 micrometers) for a standard Mid-Latitude Summer atmospheric profile, in the presence of three water clouds.
Matrix of Net Exchange Rates, spectrally integrated over the LW interval (1.71-250 micrometers) for the Venus atmosphere.

Installation

Prerequisites: a fortran compiler (no external libraries are needed). It should work fine with common compilers (gfortran, ifort, pgfortran, etc.).

Download and uncompress the .tgz archive. Then you can try to compile the karine executable: go to the main karine directory, then use the make all command to compile. The most common sources of failure can be fixed by editing the Makefile file in order to check compilation options (and more specifically options related to the target architecture and optimisations). Whenever you modify a source file, you can re-compile using the make all command. But in the case you have to modify a include file, you will have to erase all existing object files first using the make clean command, before recompiling from scratch using the make all command again.

Usage

Please refer to the documentation in order to produce the /data/atmos_data.txt input data file required by karine. A example program (make_data) is provided in the /data directory: use the f0 script in order to compile it, but this program will only produce a dummy data set (not a physical configuration). The user has the possibility to set many options and input data by editing the options.in and data.in input data files. Please refer to the documentation for a description of the content of these files.

License

Karine is free software released under the GPLv2+ license: GNU GPL version 2 or later. You can freely study, modify or extend it. You are also welcome to redistribute it under certain conditions; refer to the license for details.