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LNFL

Contents

1. Cloning
2. LNFL Docker Image
3. Building LNFL
4. Running LNFL

LNFL converts an ASCII line file parameter database (available at RTWeb) to the unformatted binary the LBLRTM expects as input. This is called a TAPE3.

If any build or run issues occur, please create an issue or contact the AER-RC Group.

Cloning the Latest Release <a name="cloning"></a>

Assuming the output directory should be LNFL:

git clone --recursive git@github.com:AER-RC/LNFL.git

--recursive is important, because this repository is linked with our common FORTRAN modules repository that are required in the model builds. If this keyword is forgotten, one can do:

git submodule init
git submodule update

in the LNFL directory.

Currently, the latest release is LNFL v3.2, and it is recommended that this be the version that users clone and checkout (rather than the master branch). To do this, one needs to simply checkout the v3.2 tag:

git checkout tags/v3.2

No releases before v3.2 are available via GitHub, but they can be requested by emailing aer_lblrtm@aer.com. For information on previous releases, please visit the What's New Wiki page.

Instead of cloning, users can also download an LNFL tarball and unpack it:

tar xvf lnfl_v3.2.tar.gz
mv LNFL-3.2/ lnfl

Though not necessary, the move to lnfl is for consistency with previous release packages and the associated documentation.

LNFL Docker Image <a name="docker"></a>

If users would like to bypass having to setup and build LNFL on their own and have Docker installed on their system, they can use the Docker Hub image for LNFL that the AER-RC group has made publicly available. Alternatively, the same image is available in the LNFL GitHub Packages. To run an LNFL container with the image (only one pull is necessary):

docker pull aerradclim/lnfl # from Docker Hub
docker tag aerradclim/lnfl lnfl

docker pull docker.pkg.github.com/aer-rc/lnfl/lnfl:latest # from GitHub
docker tag docker.pkg.github.com/aer-rc/lnfl/lnfl:latest lnfl

docker run --name lnfl --rm -v ~/Work/RC/TAPE5_2000-3250:/LNFL/TAPE5 -v ~/Work/RC/LNFL_output:/LNFL/LNFL_Out lnfl

Not all of the arguments in the previous code snippet are required. A simple docker run aerradclim/lnfl will suffice, but the user would not be providing any inputs or getting any outputs. Consequently, there are two "volume mounts" -- one for the only LNFL input (the TAPE5), and one for the outputs. The former is a single file, and the latter is a directory. In volume mounts, the path on the left side of the : is with respect to the "host" (i.e., the local machine of the user), and the path to the right of the : is the path inside the container. LNFL users should alter their host paths accordingly. Host paths should be absolute and not relative. The output directory should already exist on the host, otherwise it will be written as root and the files underneath it will only be accessible by root. BOTH VOLUME MOUNTS ARE NECESSARY TO RUN THE MODEL AND RETRIEVE ITS OUTPUT. The image name -- lnfl -- is the final argument in the call and is required.

The following are optional container arguments:

• --name: name of the container
• --rm: removes container after LNFL is finished running and staging outputs

Building LNFL <a name="build"></a>

LNFL has been built extensively only in single precision. It is not recommended that users attempt to build in double precision. To start, descend into the build directory:

cd build
make -f make_lnfl $TARGET

The TARGET environment variable depends on the user's operating system, compiler, and desired precision. Available targets are:

Running LNFL <a name="run"></a>

LNFL now accommodates the 160 character .par format adopted for HITRAN_2004. However, the default format for LNFL will remain the 100 character format. The rationale for this choice is that the vibrational data as stored in the 100 character format is more amenable to utilization in LBLRTM, particularly for LBLRTM Non-LTE calculation than that associated with the 160 character format for which the vibrational information had been expanded to facilitate association of the lines with the quantum mechanical vibrational designations.

The capability to accommodate the 160 character format is restricted to TAPE1. The TAPE2 files should be in 100 character format - you can generate this from the 160 character format by running LNFL with the 160 cahacter file as TAPE1, and then use the 100 character TAPE7 file that LNFL produces as the TAPE2 for the next run.

A few notes:

1. To facilitate the change to HITRAN2004, some of the LNFL flags on Record 3 in older releases have been distributed to Records 3 and 4. On Record 3, the flags include those that are general for the LNFL run and those that are relevant to TAPE1. On Record 4, the flags include those relevant to TAPE2 only.

2. The default for blocking has been changed. No blocking is now the default. Flags NBLK1 and NBLK2 are no longer necessary and are ignored.

3. The writing of internally stored line coupling information to TAPE2 is no longer supported. Line coupling information may be included explicitly on TAPE1 or TAPE2 by the user.

4. As of Dec. 2013, LNFL requires additional broadening parameter input files. These files are listed in the LNFL Inputs Section, and example files are included in the LNFL package. These files are only needed and used if the IBRD flag is set in the TAPE5.

5. As of Jan. 2015, LNFL allows one to specify the name of the ASCII line file at the command line rather than having to link it to TAPE1. For example, if one wanted to use aer_v_3.6 as the ASCII line file, lnfl_v3.1_linux_pgi_sgl aer_v_3.6 could be used at the command line.

LNFL Inputs <a name="inputs"></a>

Special reduced microwave ASCII line files, corresponding to the old spectral_lines.dat of MonoRTM v4.2, are provided to be used as the TAPE1 inputs of MonoLNFL in the microwave. The calculational accuracy of these reduced line lists at any frequency between 0 and 899.4 GHz (0-30 cm^-1) with respect to the corresponding full line list (aer_v_3.3) is:

• spectral_lines.dat.0_55.v5.0_fast: 0.1 K upwelling, 0.2 K downwelling
• spectral_lines.dat.0_55.v5.0_veryfast: 0.5 K upwelling, 1.0 K downwelling

A special reduced near-IR ASCII line file for the ASCENDS region (6300-6700 cm^-1) containing the first 7 HITRAN molecules is also included (spectral_lines.dat.6300_6700.v5.0). These line parameters are consistent with aer_v_3.2 and aer_v_3.3 (which are identical for wavenumbers greater than 55 cm^-1). See files headers and MonoRTM v5.0 release notes for more details.

Users who wish to run MonoRTM v5.0 in other spectral regions should use the full AER line file (aer_v_3.5), with a caution that the full line file can take a long time to run.

TAPE2 must be in older 100 character HITRAN format.

Note that LBLRTM ignores the speed dependence parameters, but they are used by MonoRTM v5.0 and later.

LNFL TAPE5 <a name="TAPE5"></a>

Record 1

Required (but ignored); 72 characters (formatted as 9 8-character strings, or 9A8) of user identification; think of this record as a documentation comment

Record 2

Required; Specifies the spectral range of the line file, with:

Record 3

Required; Specifies the molecules for which the line file is created and additional LNFL options

Available Molecular Species <a name="molecules"></a>

LNFL Options <a name="options1"></a>

Record 4

Required if MRG2 set in Record 3; TAPE2 molecules and options

Line Coupling Options <a name="options2"></a>

Record 5

Required if line rejection option (REJ) selected in Record 3

• SR(M=1,NMOL): Strength rejection value for molecule M
• 8E10.3 Format
• lines with strength values less than SR(M) will not be included on LBLRTM line file (TAPE3)
• negative value for SR(M) uses internally stored default value based on tangent path through the Earth's atmosphere
• a value of 0 for SR(M) implies no rejection for molecule M, all lines for that molecule are retained
• values for SR(M) are relative to LBLRTM line strengths, which are equal to HITRAN strengths / ( v * (1-e^v/kT))
• NMOL is 7 or the number of the highest molecule selected, whichever is larger

LNFL Outputs <a name="output"></a>