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In this case study, there are two operational ensemble datasets, one from the original 2012 operational forecast, the other from a reforecast of the event using the 2016 operational ensemble.
An ensemble forecast consists of:
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Key parameters: MSLP and z500. We suggest concentrating on viewing these fields. If time, visualize other parameters (e.g. PV320K).
Available plot types
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TODO: Any macro that computes a difference to analyses needs to move to the last exercise on 'Forecast differences'. Any macro that uses analysis to plot use HRES forecast instead. |
Available plot types
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this will plot (a) the mean of the ensemble forecast, (b) the ensemble spread, and (c) the HRES deterministic forecast.
this plots a 'spaghetti map' for a given parameter for the ensemble forecasts compared to the reference HRES forecast. Another way of visualizing ensemble spread.
this plots a vertical cross-section through the forecasts in the same way as the cross-section plots for the analyses. |  Image Added
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TODO: these need updating |
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For these exercises please use the Metview icons in the row labelled 'ENS'. TODO: move ens_rmse.mv & stamp_diff.mv to folder Forecast Differences ens_to_an.mv : this will plot (a) the mean of the ensemble forecast, (b) the ensemble spread, (c) the HRES deterministic forecast and (d) the analysis for the same date. TODO: remove 'AN' from this & rename ens_mean_spread.mv ens_to_an_runs_spag.mv : this plots a 'spaghetti map' for a given parameter for the ensemble forecasts compared to the analysis. Another way of visualizing ensemble spread. TODO: remove 'AN' from this and replace with HRES & rename ens_spag.mv stamp.mv : this | plots all of the ensemble forecasts for a particular field and lead time. Each forecast is shown in a stamp sized map. Very useful for a quick visual inspection of each ensemble forecast. |
Additional plots for further analysis:  Image Removed
pf_to_cf_diff.mv :  Image Added
| this useful macro allows two individual ensemble |
| forecasts to be compared to the control forecast. As well as plotting the forecasts from the members, it also shows a difference map for each. |  Image Added
| this will plot the difference between the ensemble control, ensemble mean or an individual ensemble member and the HRES forecast for a given parameter. |  Image Added
| this macro produced a single map for a given parameter. The map can be either: i/ the ensemble mean, ii/ the ensemble spread, iii/ the control forecast, iv/ a specific perturbed forecast, v/ map of the ensemble probability subject to a threshold, vi/ ensemble percentile map for a given percentile value. For example, it is possible to plot of a map showing the probability that MSLP would be below 995hPa. |  Image Added
| this macro can be used to plot the difference for two ensemble members against the HRES forecasts. As ensemble perturbations are applied in +/- pairs, using this macro it's possible to see the nonlinear development of the members and their difference to the HRES forecast |
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Group working
If working in groups, each group could follow the tasks below with a different ensemble forecast. e.g. one group uses the 'ens_oper', another group uses 'ens_2016'.
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stamp.mv : this plots all of the ensemble forecasts for a particular field and lead time. Each forecast is shown in a stamp sized map. Very useful for a quick visual inspection of each ensemble forecast.