Package: jcclass
Jenkinson - Collison automated gridded classification for PythonThis is an adapted version for python of theJenkinson - Collisonautomated classfication based on the original Lamb Weather Types. This gridded version is based on the application made byOtero(2018) using a moving central gridded point with  that allows to compute the synoptic circulation types on a gridded Mean Sea Level Pressure (MSLP) domain.How does it work?The method uses grid-point MSLP data to obtain numerical values of wind flow and vorticity which can be used to determine Cyclonic and Anticyclonic patterns as well as their dominant advective (direction of wind flow) characteristics. The 16 gridded points are moved along the region in reference to a central point where the dominant circulation type will be designated.The Circulation Types (CTs)The application of the automated classification allows to derive 27 synoptic circulations. 26 of them based on the dominant pressure pattern and wind direction plus a Low Flow (LF) type which is characterised by days when pressure gradients are to weak and a dominant circulation or advective direction can not be assigned.NameAbreviationCodingNameAbreviationCodingNameAbreviationCodingLow FlowLF-1AnticyclonicA0CyclonicC20Anticyclonic NortheasterlyANE1NortheasterlyNE11Cyclonic NortheasterlyCNE21Anticyclonic EasterlyAE2EasterlyE12Cyclonic EasterlyCE22Anticyclonic SoutheasterlyASE3SoutheasterlySE13Cyclonic SoutheasterlyCSE23Anticyclonic SoutherlyAS4SoutherlyS14Cyclonic SoutherlyCS24Anticyclonic SouthwesterlyASW5SouthwesterlySW15Cyclonic SouthwesterlyCSW25Anticyclonic WesterlyAW6WesterlyW16Cyclonic WesterlyCW26Anticyclonic NorthwesterlyANW7NorthwesterlyNW17Cyclonic NorthwesterlyCNW27Anticyclonic NortherlyAN8NortherlyN18Cyclonic NortherlyCN28The original 27 circulations can be reduced to a set of 11 patterns based on their dominant advection.NameAbreviationCodingLow FlowLF-1AnticyclonicA0NortheasterlyNE1EasterlyE2SoutheasterlySE3SoutherlyS4SouthwesterlySW5WesterlyW6NorthwesterlyNW7NortherlyN8CyclonicC9Working datasetsThe current code has been has been tested for the following datasets:ERA5Reanalysis
-NOAA20th Century Reanalysis (V3)Global Climate Models from the Coupled Model Intercomparison Project (CMIP6)The method can be applied for any other netcdf files with latitude coordinates names as "latitude" or "lat", or longitudes coordinates as "longitude" or "lon" and MSLP coordinate names as "msl" or "psl".Sample datasets from ERA5 is provided and availablehereInstallationSimply run in the terminalpip install jcclassHow to use?Importing the modulefromjcclassimportjcComputing the automated circulation types based on gridded MSLPSample datasets availablehere.filename='era5_daily_lowres.nc'cts_27=jc(filename).classification()Computing the reduced eleven circulation typescts_11=jc.eleven_cts(cts_27)Ploting the circulation types on a mapimportxarrayasxrdate=cts_27.time[0]#selecting the first timects=cts_27.sel(time=date)fig=jc.plot_cts(cts,*args)cts   : a 2D['lat','lon']  xarray.DataArray of the 27 CTs*args : int,optional(lat_south, lat_north, lon_west, lon_east)Plotting the circulation types and MSLP contour lines on a mapimportxarrayasxrmslp=xr.open_dataset(filename).sel(time=date)fig=jc.plot_cts_mslp(cts,mslp,*args)cts   : a 2D['lat','lon']  xarray.DataArray of the 27 CTsmslp  : a 2D['lat','lon'] xarray.Dataset of MSLP*args : int,optional(lat_south, lat_north, lon_west, lon_east)Plotting the circulation types and MSLP contour lines on a Nearside perspective cartopy projectionfig=jc.plot_cts_globe(cts,mslp,*argsglobe)cts   : a 2D['lat','lon']  xarray.DataArray of the 27 CTsmslp  : a 2D['lat','lon'] xarray.Dataset of MSLP*argsglobe : int,optional(lat_central=30, lon_central=0)Saving the figuresYou can save anytime any of the figures usingfig.savefig.fig.savefig('figname.png',dpi=150)DocumentationDetailed documentation and tutorial on thejcclassmodule can be found in theDocumentationAcknowledging this workThe code can be used and modified freely without any restriction. If you use it for your own research, I would appreciate if you cite this work as follows:Herrera-Lormendez P., 2022: PedroLormendez/jcclass: version x.y.zdoi:10.5281/zenodo.7025220Reports on errors are welcomed byraising an issueFurther literature on the methodJenkinson AF, Collison FP. 1977. An Initial Climatology of Gales over the North Sea. Synoptic Climatology Branch Memorandum, No. 62., Meteorological Office, Bracknell.Lamb HH. 1972. British Isles weather types and a register of daily sequence of circulation patterns, 1861-1971: Geophysical Memoir. HMSO.Jones PD, Hulme M, Briffa KR. 1993. A comparison of Lamb circulation types with an objective classification scheme. International Journal of Climatology. John Wiley & Sons, Ltd, 13(6): 655–663.https://doi.org/10.1002/joc.3370130606.Otero N, Sillmann J, Butler T. 2018. Assessment of an extended version of the Jenkinson–Collison classification on CMIP5 models over Europe. Climate Dynamics. Springer Verlag, 50(5–6): 1559–1579.https://doi.org/10.1007/s00382-017-3705-y.