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Please enter the folder 'openifs_2019' to begin working. |
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| title | Saving images and animations |
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Exercise 1: Hurricane Nadine and the cut-off low
ECMWF analyses to the 20th September 2012
In this exercise, the development of Hurricane Nadine and the cut-off flow up to the 20th September 2012 is studied.
Begin by entering the folder labelled 'Analysis':
Task 1: Mean-sea-level pressure and track
This task will look at the synoptic development of Hurricane Nadine and the cutoff low up to 00Z, 20th September 2012. The forecasts in the next exercises start from this time and date.
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an_1x1.mv : this plots horizontal maps of parameters from the ECMWF analyses overlaid on one plot. an_2x2.mv : this plots horizontal maps of parameters from the ECMWF analyses four plots to a page (two by two). |
Right-click on the an_1x1.mv icon and select the 'Visualise' menu item (see figure)
After a pause, this will generate a map showing mean-sea-level pressure (MSLP).
Drag and drop the mv_track.mv icon onto the map to add the track of Hurricane Nadine.
In the plot window, use the play button in the animation controls 
to animate the map and follow the development and track of Hurricane Nadine.
You can use the 'Speed' menu to change the animation speed (each frame is every 6 hours).
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If the contour lines appear jagged, in the plot window, select the menu item 'Tools -> Antialias'. |
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Q. What is unusual about Hurricane Nadine? |
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The macros described in this tutorial can write PostScript and GIF image files to the To save the images, use the 'Execute' menu option on the icon, rather than 'Visualise'. The 'okular' command can be used to view the PDF & gif images. |
To save any other images during these exercises for discussion later, you can either use:
"Export" button in Metview's display window under the 'File' menu to save to PNG image format. This will also allow animations to be saved into postscript.
or use the ksnapshot command to take a 'snapshot' of the screen and save it to a file.
If you want to create animations from other images, save the figures as postscript and then use the convert command:
convert -delay 75 -rotate "90<" in.ps out.gif...
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| title | Saving images |
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| title | Saving images and animations |
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| Info |
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The macros described in this tutorial can write PostScript and GIF image files to the To save the images, use the 'Execute' menu option on the icon, rather than 'Visualise'. The 'okular' command can be used to view the PDF & gif images. |
To save any other images during these exercises for discussion later, you can either use:
"Export" button in Metview's display window under the 'File' menu to save to PNG image format. This will also allow animations to be saved into postscript.
or use the ksnapshot command to take a 'snapshot' of the screen and save it to a file.
If you want to create animations from other images, save the figures as postscript and then use the convert command:
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convert -delay 75 -rotate "90<" in.ps out.gif |
Exercise 1: Hurricane Nadine and the cut-off low
ECMWF analyses to the 20th September 2012
In this exercise, the development of Hurricane Nadine and the cut-off flow up to the 20th September 2012 is studied.
Begin by entering the folder labelled 'Analysis':
Task 1: Mean-sea-level pressure and track
This task will look at the synoptic development of Hurricane Nadine and the cutoff low up to 00Z, 20th September 2012. The forecasts in the next exercises start from this time and date.
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an_1x1.mv : this plots horizontal maps of parameters from the ECMWF analyses overlaid on one plot. an_2x2.mv : this plots horizontal maps of parameters from the ECMWF analyses four plots to a page (two by two). |
Right-click on the an_1x1.mv icon and select the 'Visualise' menu item (see figure)
After a pause, this will generate a map showing mean-sea-level pressure (MSLP).
Drag and drop the mv_track.mv icon onto the map to add the track of Hurricane Nadine.
In the plot window, use the play button in the animation controls to animate the map and follow the development and track of Hurricane Nadine.
You can use the 'Speed' menu to change the animation speed (each frame is every 6 hours).
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If the contour lines appear jagged, in the plot window, select the menu item 'Tools -> Antialias'. |
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Q. What is unusual about Hurricane Nadine? |
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Please close any unused plot windows if using a virtual machine. This case study uses high resolution data over a relatively large domain. Multiple plot windows can therefore require significant amounts of computer memory which can be a problem for virtual machines with restricted memory. |
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For those interested: The code that computes the clusters can be found in the Python script: This uses the 'ward' cluster method from SciPy. Other cluster algorithms are available. See http://docs.scipy.org/doc/scipy/reference/generated/scipy.cluster.hierarchy.linkage.html#scipy.cluster.hierarchy.linkage The python code can be changed to a different algorithm or the more adventurous can write their own cluster algorithm! |
Exercise 5: Assessment of forecast errors
The python code can be changed to a different algorithm or the more adventurous can write their own cluster algorithm! |
Exercise 5: Assessment of forecast errors
In this exercise, the analyses covering the forecast period are now available to see how Nadine and the cut-off low actually behaved.
Various methods for presenting the forecast error are used in the tasks below. The clusters created in the previous exercise can also be used.
Enter the 'Forecast errors' folder in the openifs_2018 folder to start work on this exercise.
Task 1: Analyses from 20th September
Now look at the analyses from 20th Sept to observe what actually happened.
Right-click an_1x1.mv, Edit and set the plot to show MSLP and geopotential at 500hPa:
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plot1=["z500.s","mslp"] |
Click the play button and animate the plot to watch In this exercise, the analyses covering the forecast period are now available to see how Nadine and the cut-off low actually behaved.
Various methods for presenting the forecast error are used in the tasks below. The clusters created in the previous exercise can also be used.
Enter the 'Forecast errors' folder in the openifs_2018 folder to start work on this exercise.
Task 1: Analyses from 20th September
Now look at the analyses from 20th Sept to observe what actually happened.
Right-click an_1x1.mv, Edit and set the plot to show MSLP and geopotential at 500hPa:
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plot1=["z500.s","mslp"] |
Click the play button and animate the plot to watch how Nadine and the cut-off low behave.
Drop the mv_track.mv icon to overlay the track of Nadine onto the map.
If time, use the other icons such as an_2x2.mv and an_xs.mv to look at the cross-section through the analyses and compare to the forecast cross-sections from the previous exercises.
Task 2: Compare forecast to analysis
Plot forecast difference maps to see how and when the forecast differed from the analyses.
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Use the hres_to_an_diff.mv icon and plot the differences between the z500, MSLP and other fields to how the forecast differences evolve.
Also try the ctrl_to_an_diff.mv icon which plots the difference but this time using the ensemble control forecast.
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Q. How does the behaviour of Nadine and the cut-off low differ from the HRES deterministic forecast and the ensemble control forecast? |
Task 4: RMSE "plumes" for the ensemble
This is similar to the previous exercise, except the RMSE curves for all the ensemble members from a particular forecast will be plotted.
Right-click the ens_rmse.mv icon, select 'Edit' and plot the curves for 'mslp' and 'z500'.
Change 'expID' for your choice of ensemble (either ens_oper or ens_2016).
Clusters
First plot the plumes with clustering off:
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clustersId="off" |
There might be some evidence of clustering in the ensemble plumes.
There might be some individual forecasts that give a lower RMS error than the control forecast.
Next, use the cluster files created from the earlier exercise. You can use either your own created cluster file as before, or use the EOF generated file.
For example:
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clustersId="eof" |
would use the cluster definitions in the file: ens_oper_cluster.eof.txt (for the 2012 operational ensemble).
behave.
Drop the mv_track.mv icon to overlay the track of Nadine onto the map.
If time, use the other icons such as an_2x2.mv and an_xs.mv to look at the cross-section through the analyses and compare to the forecast cross-sections from the previous exercises.
Task 2: Compare forecast to analysis
Plot forecast difference maps to see how and when the forecast differed from the analyses.
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Use the hres_to_an_diff.mv icon and plot the differences between the z500, MSLP and other fields to how the forecast differences evolve.
Also try the ctrl_to_an_diff.mv icon which plots the difference but this time using the ensemble control forecast.
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Q. How does the behaviour of Nadine and the cut-off low differ from the HRES deterministic forecast and the ensemble control forecast? |
Task 4: RMSE "plumes" for the ensemble
This is similar to the previous exercise, except the RMSE curves for all the ensemble members from a particular forecast will be plotted.
Right-click the ens_rmse.mv icon, select 'Edit' and plot the curves for 'mslp' and 'z500'.
Change 'expID' for your choice of ensemble (either ens_oper or ens_2016).
Clusters
First plot the plumes with clustering off:
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clustersId="off" |
There might be some evidence of clustering in the ensemble plumes.
There might be some individual forecasts that give a lower RMS error than the control forecast.
Next, use the cluster files created from the earlier exercise. You can use either your own created cluster file as before, or use the EOF generated file.
For example:
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clustersId="eof" |
would use the cluster definitions in the file: ens_oper_cluster.eof.txt (for the 2012 operational ensemble).
The cluster files are 'linked' from the Cluster folder, but if they do not work, just copy the cluster file (e.g. ens_oper_cluster.eof.txt) to the Forecast_errors folder.
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Q. How do the HRES, ensemble control forecast and ensemble mean compare? |
Task 5: Difference stamp maps
Use the stamp_diff.mv plot to look at the differences between the ensemble members and the analysis. It can be easier to understand the difference in the ensembles by using difference stamp maps.
Note, stamp_diff.mv cannot be used for 'tp' as there is no precipitation data in the analyses.
Clustering can also be enabled for this taskThe cluster files are 'linked' from the Cluster folder, but if they do not work, just copy the cluster file (e.g. ens_oper_cluster.eof.txt) to the Forecast_errors folder.
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Q. How do the HRES, ensemble control forecast and ensemble mean compare? |
Task 5: Difference stamp maps
Use the stamp_diff.mv plot to look at the differences between the ensemble members and the analysis. It can be easier to understand the difference in the ensembles by using difference stamp maps.
Note, stamp_diff.mv cannot be used for 'tp' as there is no precipitation data in the analyses.
Clustering can also be enabled for this task.
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Q. Using the stamp and stamp difference maps, study the ensemble. Identify which ensembles produce "better" forecasts. |
Using the stamp and stamp difference maps, study the ensemble. Identify which ensembles produce "better" forecasts. |
Appendix
| Anchor | ||||
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| Info |
|---|
The macros described in this tutorial can write PostScript and GIF image files to the To save the images, use the 'Execute' menu option on the icon, rather than 'Visualise'. The 'okular' command can be used to view the PDF & gif images. |
To save any other images during these exercises for discussion later, you can either use:
"Export" button in Metview's display window under the 'File' menu to save to PNG image format. This will also allow animations to be saved into postscript.
or use the ksnapshot command to take a 'snapshot' of the screen and save it to a file.
If you want to create animations from other images, save the figures as postscript and then use the convert command:
| Code Block |
|---|
convert -delay 75 -rotate "90<" in.ps out.gif |
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Further reading
For more information on the stochastic physics scheme in IFS, see the article:
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