Page History
...
Note: HRES and Ensemble Control Forecast are scientifically, structurally and computationally identical. With effect from Cy49r1, Ensemble Control Forecast output is equivalent to HRES output shown in the diagrams. At the time of the diagrams, HRES had resolution of 9km and ensemble members had a resolution of 18km.
Lightning
The Lightning Flash Density forecast products are available on ecCharts and can be accessed via the Layers dropdown menu.
...
The diagnostics aim to represent cloud-to-ground plus intra-cloud lightning strikes. Note that many ground-based lightning sensing systems are much more adept at identifying cloud-to-ground strikes.
Fig8.1.13-1(left): ecCharts display of lightning flash density (average strikes/100km2/h average during the previous 6h) from HRES.
...
In the example in Fig8.1.13-1, values for Bordeaux (location shown by the pin) are given in the probe display at the top. HRES forecast shows less than 1 strike per hour within the surrounding 100km2 average during the previous 6 hours. However, ensemble forecasts give a probability for the same period of 45% for an average of more than 2 strikes per hour, and 80% for an average of more than 0.1 strikes per hour during the same period.
Considerations when using Lightning charts
The parametrization of total lightning flash density uses the following quantities diagnosed from the ECMWF convection scheme:
...
The probability of lightning activity is a good indicator of the risk of lightning strikes at a given location. Selection of the threshold for lightning strike density allows the user to assess the risk at a location or within an area. Selecting a low threshold (e.g. 0.1 strikes/100km2/h during the previous 3h) gives an indication of whether any lightning activity can be expected at all. For many customers this is the aspect that is of primary interest.
Fig8.1.13-2: Mean correlation, for lightning flash density over Europe in summer 2015, between IFS short range forecasts and ground based observations, as a function of averaging spatial resolution (x-axis), and for different averaging periods (different lines). Model forecasts of lightning activity should not be considered as being precise in time and space but rather as indicators of activity within a region, with there being greater confidence for larger areas over longer time scales. Note lightning flash density is displayed on ecCharts as units per 100km2 (equates to spatial resolution ~ 0.1o).
Fig8.1.13-3: Mean normalised diurnal cycle of lightning activity from IFS short-range forecasts (black line) against three ground-based observation networks of lightning sensors (coloured) over Europe in summer 2015. Model forecasts of lightning activity decay away too early in the afternoon while in reality thunderstorms continue through the afternoon and often linger well into the night.
Fig8.1.13-4: a)Observed mean lightning flash densities over 6hr, b)Probability (>30%) of lightning flash density exceeding 0.5 flashes 100km-2 hr-1 derived from ENS.
The charts illustrate that on the broad scale the forecasts capture the areas at risk, but the location of the activity is rather imprecise.
Fig8.1.13-5 Time series of daily mean lightning flash densities from IFS short-range forecasts (blue) and from ground-based observation network of lightning sensors (red) over Europe during summer 2015. The IFS forecast lightning activity tends to be too intense, particularly during periods of higher activity.
Fig8.1.13-6: Annual mean lightning flash densities from a) satellite climatology and b)10 year-long IFS model runs. IFS tends to underestimate activity, more particularly over central Africa but also evident over parts of eastern Europe and central Asia. Conversely, it is possible there is too much activity forecast over parts of the tropical Pacific.
Fig8.1.13-7: Seasonal mean lightning flash density for months SON from 15 years of observations (left) and from 10 year-long 80km IFS simulations (right). The scale is in flashes/km2/year. Agreement for other seasons (not shown) is much better.
Additional Sources of Information
(Note: In older material there may be references to issues that have subsequently been addressed)
...
Overview
Community Forums
Content Tools