Versions Compared

Old Version 5

changes.mady.by.user Bob Owens

Saved on

compared with

New Version 6

changes.mady.by.user Bob Owens

Saved on

Key

  • This line was added.
  • This line was removed.
  • Formatting was changed.

Table of Contents

ecCharts

ecCharts is a web-based presentation system developed to show a very wide range of ECMWF IFS model output worldwide in chart form, and in a very flexible way under the control of the user.  This allows ECMWF's medium-range forecasts to be viewed in far greater detail than was previously possible on the web, with panning and zooming being key functionalities that are not provided by the standard web charts.  ecCharts allows several forecast fields to be superimposed for ease of inter-comparison.  These charts may be animated throughout the forecast period as an aid to understanding the forecast structure of the atmosphere.  Ensemble output may be displayed in probabilistic form or as several derived fields (e.g.vorticity, divergence, CAPE, CAPE-shear, etc).  Also are simulated IR and WV images derived using the control member (CTRL) of the medium range ensemble.   A probe tool is provided to allow display of values at a selected point at the chart time.  Results from the latest and previous forecast runs are also readily available.  Time sequences of variables at a selected point can also be displayed in graph form.  

ecCharts documentation gives a clear and comprehensive description of options and practical use of ecCharts.

Comparing fields for consistency

Ideally, simulated water vapour images can be compared with water vapour imagery to allow an assessment of any departure of the analysed and forecast fields from reality.  The structure of the IFS model atmosphere may also be explored by comparing the water vapour imagery with the potential vorticity fields.  Currently satellite imagery is not available on ecCharts and comparison of observed and simulated imagery cannot be done directly.

...

Fig10.2.3: ecChart DT 00Z 8 August 2017 T+00 VT 00Z 8 August 2017 from HRES showing the simulated water vapour image and 300hPa potential vorticity.  These can be compared with WV satellite imagery to highlight discrepancies between the modelled atmosphere and reality.  Stratospheric air (PV=2 taken as near the tropopause, greater PV values (shown purple)) imply stratospheric air has descended to 300hPa.  Descent is also implied by the darker areas of the simulated water vapour image.  Comparing WV imagery with simulated imagery and PV charts can provide a powerful method of identifying discrepancies between the modelled atmosphere and reality.

Considerations when using ecCharts

Although comprehensive and detailed investigations and presentations are possible with ecCharts, a few points should be considered when interpreting the data:

...