About
vortex-moments contains scripts to calculate moment diagnostics for the stratospheric polar vortex. These can be used, for instance, to diagnose split and displaced vortex events, as described in Seviour et al., 2013.
- This repository contains two main scripts vor.py (a Python script) and vor.pro (an IDL script). vor.pro was written by Dann Mitchell, and vor.py was written by William Seviour. Both scripts calculate moment diagnostics using a similar method.
- Required packages are
numpyandscipy.interpolate. - Example uses:
vor.py:
import vor
d = vor.calc_moments(field,lats,lons,'NH','GPH',29600)vor.pro:
d=VOR(field,lon,lat,/GP,EDGE=3.02e4)-
For a full example of using vor.py, please see moments_1979_example. Note this may take about 15 minutes to run on a normal PC.
-
There is now a faster verion vor_fast.py which is intended for calculating a timeseries over many timesteps. The lat/lon to cartesian mapping is calculated only once in this routine. vor_fast_setup.py must be run first to calculate this mapping. See moments_fast_example.py for an example of use. This runs in about 10 minutes (a 1/3 saving over vor.py). Update: with
resolution='low'enabled this runs in about 1.5 minutes.
To Do
The moment_integrate function is currently restricting speed the most. It might be possible to use more efficient integration algorithms.
Citations
If you use the Python script vor.py please cite:
Seviour, W. J. M., D. M. Mitchell, and L. J. Gray (2013), A practical method to identify displaced and split stratospheric polar vortex events, Geophys. Res. Lett., 40, 5268-5273 doi:10.1002/grl.50927
If you use the IDL script vor.pro please cite:
Mitchell, D.M., Charlton-Perez, A.J. and Gray, L.J. Characterising the Variability and Extremes of the Stratospheric Polar Vortices Using 2D Moments, J.Atmos.Sci., 1194-1213, 2011. doi:10.1175/2010JAS3555.1