5.1. Introduction

FLEXPART (“FLEXible PARTicle dispersion model”) is a Lagrangian transport and dispersion model suitable for the simulation of a large range of atmospheric transport processes. Apart from transport and turbulent diffusion, it is able to simulate dry and wet deposition, decay, linear chemistry; it can be used in forward or backward mode, with defined sources or in a domain-filling setting. It can be used from local to global scale. A version of FLEXPART for use with the Norwegian Earth System Model (NorESM1-M) has been created in 2016 and since than it has been updated with the current parametrizations used in the newest FLEXPART version, as well as compatibility to run with NorESM2.

The offline FLEXible PARTicle (FLEXPART) stochastic dispersion model is currently a community model used by many scientists. The transport of pollutants, but also pysichal properties (e.g. moisture) is the main application. It provides an advanced tool to directly analyse and diagnose atmospheric transport properties of the state-of-the-art climate model NorESM in a reliable way. Extensive evaluation confirmed the effectiveness of the combined modelling system FLEXPART with NorESM in producing realistic transport statistics.

The documentation of FLEXPART-NORESM has been published in GMD and can be found here: assiani, M., Stohl, A., Olivié, D., Seland, Ø., Bethke, I., Pisso, I., and Iversen, T.: The offline Lagrangian particle model FLEXPART–NorESM/CAM (v1): model description and comparisons with the online NorESM transport scheme and with the reference FLEXPART model, Geosci. Model Dev., 9, 4029–4048, ​https://doi.org/10.5194/gmd-9-4029-2016, 2016.

5.2. Downloading FLEXPART-NorESM from the repository

The source codes of the FLEXPART-NorESM are developed and maintained on the git.nilu.no

git clone https://git.nilu.no/flexpart/flexpart-noresm.git

5.3. Compilation on BETZY

in the directory $src

module load netCDF-Fortran/4.4.5-gompi-2019a

make sure that also the INCPATH variable points to the same netCDF library version: INCPATH  = /cluster/software/netCDF-Fortran/4.4.5-gompi-2019a/include/ in makefile_betzy

make -f makefile_betzy

5.4. Preparation of the FLEXPART installation

The pathnames, located in the directory $test (flexpart_noresm/test) contains all the directories which are used by FLEXPART.

In the pathnames file is the path of the AVAILABLE, which shows the location of the meteorological data. Right now it is set up that the testwindfield should be located in $test The test windfield is not part of the git repository, but can be retrieved with:

wget https://folk.nilu.no/~sabine/NSSP585frc2_f09_tn14_TESTFIELD.nc

in the second line of the pathnames file is a link to the output directory, this has to been created, e.g.

mkdir $test/output

5.5. Test of the FLEXPART installation

This test runs a backward simulation for a couple of hours from a point. The result of the simulation (variable spec001_mr), summed over all heights and time steps, should look like following plot, (depicted in log10 scale)

alternate text

For the test there are all control files provided, NorESM2 input files are downloaded as described above. This is sufficient for performing a sevaral hours backward calculation. To run it you need to type

salloc --nodes=1 --time=00:30:00 --qos=devel --account=nnXXXXk

cd $test


5.6. Modifications since version FLEXPART-NorESM 1.0

  1. netcdf output

  2. updated scavenging parametrization (Grythe et al., 2017), https://gmd.copernicus.org/articles/10/1447/2017/

  3. inputfile/program files defining the grid used in NorESM2 updated (grid_atm_288x192.nc)

  4. species definition in namelist format, introduction of command line parameters

5.7. Precalculated examples

Based on CMIP6 simulations from NorESM2 backward calculations for a BC tracer as well as a passive tracer has been established. The receptors for the simulations are 4 different Arctic stations and the model has been run until 2100 showing weekly footprints of the air masses origin at this stations. The results can be viewed here: https://niflheim.nilu.no/SabinePY/INES.py