Ensemble Tool

Fig. 1 Legends tab of the Ensemble Tool displaying the mean surface temperature of the 21 GFS Ensemble members as an image field with a 95 degree contour overlayed.


Training Job Sheets (click on "html" for web page layout with image links) 


  • Use the Ensemble Tool with the Volume Browser to create ensemble-derived plots like Max precip of all members (see Fig 1) and relative frequency distributions of certain thresholds (e.g. frequency of members of precip > 0.2"), sample individual members values, and sample with a histogram.

Refresher Commands:

  • Loading the Ensemble Tool - select Ensemble Tool from Tools menu
  • Loading Ensembles - load GEFS data (temperature or precip) in Volume Browser by clicking on the Open Volume Browser icon in upper right, see Fig. 1.
    • e.g. Sources->GEFS, Fields->Ensemble->GFS Ensembles->MSLP->MSLP Ens Members (note your VB can have different menus)
  • Create Ensembles Derived Field - after loading ensemble members, click on gear icon in upper right of Ensemble Tool and select field (e.g. Max or Sampling) 
    • Derivation based off the ensemble members that are currently visible in the associated CAVE editor
  • Right Click Row in Grid Products Section - to configure display settings for individual members (e.g. p1) or whole ensemble (three bar row)
    • Generate relative frequency, change all member colors with a color gradient, and to unload all members
  • Load as Image
    • Right click on each individual member and select Load as Image
    • To load calculations (min, max, etc.), you must click on the gear icon in the top right and select the desired calculation with an Image label
  • Contour Control
    • Contour a specific value by right clicking on a parameter and selecting Contour Control
  • Toggle Visibility - left clicking on individual model member (e.g. p18) or for all members left click on three horizontal bars next to product name (e.g. GEFS Sfc Precipitation (in) in Fig. 1)
    • Visibility of individual members affects subsequent calculations like Max, Min, etc.
  • Loading Model Families - click on the Matrix button and the "Open a Model Family" icon to its right.
    • Select a Model Family and use the Ctrl button to multiple select models under the Sources column.
    • Hover over products to identify what they are and select products you want to display.
    • Click on model names to toggle between models.
    • Build 17.3.1 has caused some faulty behavior when using the Matrix tab, which is addressed in Build 18.1.1

Usage Tips

  • Pay attention to what is viewable in the CAVE editor because that will only be used in the derived calculations
  • To more easily view derived fields, toggle off all individual members by clicking on the three horizontal bars icon
  • If the multicolor display is overwhelming, you can change line colors (e.g. single color gradient) with a right click on the main product row with the three horizontal bars.
  • The Matrix display of Model Families is memory intensive, so only toggle on what you want to view before stepping through frames or models.


  • GEFS (GFS ensemble) precip and surface temperature data is the primary ensemble option at WFOs to use with Ensemble Tool 
  • Ensemble Tool cannot be saved into a bundle/procedure



  • Michael.A.Magsig@noaa.gov