Easy-ERA5-Trck

Easy-ERA5-Trck is a super lightweight Lagrangian model for calculating thousands (even millions) of trajectories simultaneously and efficiently using ERA5 data sets. It implements super simplified equations of 3-D motion to accelerate integration, and python multiprocessing to parallelize the integration tasks. Due to its simplification and parallelization, Easy-ERA5-Trck performs great speed in tracing massive air parcels, which makes areawide tracing possible.

Another version using WRF output to drive the model can be found here.

Caution: Trajectory calculation is based on the nearest-neighbor interpolation and first-guess velocity for super efficiency. Accurate calculation algorithm can be found on http://journals.ametsoc.org/doi/abs/10.1175/BAMS-D-14-00110.1, or use a professional and complicated model e.g. NOAA HYSPLIT instead.

Any question, please contact Zhenning LI (zhenningli91@gmail.com)

Galleries

Tibetan Plateau Air Source Tracers

Tibetan Plateau Air Source Tracers (3D)

Input Files

input.csv

./input/input.csv: This file prescribe the air parcels for trajectory simulation. The format of this file:

airp_id, init_lat, init_lon, init_h0 (hPa)

For forward trajectory, the init_{lat|lon|h0} denote initial positions; while for backward trajectory, they indicate ending positions.

config.ini

./conf/config.ini: Configure file for the model. You may set ERA5 input file, input frequency, integration time steps, and other settings in this file.

Module Files

run.py

./run.py: Main script to run the Easy-ERA5-Trck.

lagrange.py

./core/lagrange.py: Core module for calculating the air parcels Lagrangian trajectories.

air_parcel.py

./lib/air_parcel.py: Module file containing definition of air parcel class and related methods such as march and output.

cfgparser.py

./lib/cfgparser.py: Module file containing read/write method of the config.ini

preprocess_era5inp.py

./lib/preprocess_era5inp.py: Module file that defines the field_hdl class, which contains useful fields data (U, V, W...) and related method, including ERA5 grib file IO operations.

Output Files

You could choose output files as plain ascii csv format or netCDF format (Recommended). netCDF format output metadata looks like:

netcdf meiyu.ynl.I19980610000000.E19980605000000 {
dimensions:
    time = 121 ;
    parcel_id = 413 ;
variables:
    double xlat(time, parcel_id) ;
        xlat:_FillValue = NaN ;
    double xlon(time, parcel_id) ;
        xlon:_FillValue = NaN ;
    double xh(time, parcel_id) ;
        xh:_FillValue = NaN ;
    int64 time(time) ;
        time:units = "hours since 1998-06-10 00:00:00" ;
        time:calendar = "proleptic_gregorian" ;
    int64 parcel_id(parcel_id) ;
}

xigrug / easy-era5-trck