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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 following ksnapshot command to take a 'snapshot' of the screen :

ksnapshot

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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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).

Use the an_1x1.mv or the an_2x2.mv macros to compare the ECMWF analyses with the satellite images.

Drag and drop the mv_track.mv icon onto the map to add the track of Hurricane Nadine.

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#Define plot list (min 1- max 4)
plot1=["mslp"]                      # use square brackets when overlaying multiple fields per plot

plot1=["z500.s","mslp"]

Use the an_1x1.mv (or the an_2x2.mv) to plot fields of your choice and compare with the satellite images.

plot1=["pv320K"]

plot1=["z500.s","pv320K","mslp"]

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Exercise 1 looked at the synoptic development up to the 20-Sept-2012. This exercise looks at the ECMWF HRES forecast from this date and how the IFS model developed the interaction between Hurricane Nadine and the cut-off low.

Enter the folder 'HRES_forecast' in the 'openifs_2018' folder to begin.

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Data is provided for a single 5 day forecast starting from 20th Sept 2012, as used in the paper by Pantillon et al. referred to at the start of this tutorial.

Data is Data is provided at the same resolution as the operational model, in order to give the best representation of the Hurricane and cut-off low iterations. This may mean that some plotting will be slow.

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The parameters available in the analyses are also available in the forecast data.

Available plot types

Task 1: Synoptic development (day 0-5)

From 20th to 25th September, Nadine had lost hurricane intensity and was slowly moving over the North Atlantic. A short-wave trough separated into a cutoff and approached from the north. Nadine interacted with a cold front associated with the cutoff on 21st September.Study the interaction of the systems and their subsequent development.

MSLP and geopotential height

First plot the geopotential at 500hPa and MSLP (as in figure 1 in Pantillon et al.) using the hres_1x1.mv macro script to see the large scale circulation and track the development of the systems:

plot1=["z500.s","mslp"]

Temperature and mid-troposphere patterns

Next use the Using either the hres_1x1.mv or hres_2x2.mv macro plot some of these other maps to study the synoptic development. Note for example that there should not be a strong horizontal temperature gradient around Nadine (why?) and the winds should be stronger for Nadine than the cutoff.

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to plot additional fields. Right click and select 'Edit' and change the plot list to:

plot1=["t2","mslp"]
plot2=["mslp","wind10"]
plot3=["t500","z500"]
plot4=["t850","z850"]

• "t2", "mslp"            :  2m-temperature and MSLP - low level signature of Nadine and temperature.
• "mslp", "wind10"

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•     : MSLP + 10m winds  -   interesting for Nadine's tracking and primary circulation.
• "

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• t500","

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• z500"

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•         : Geopotential + temperature at 500hPa  -  large scale patterns, mid-troposphere position of warm Nadine and the cold Atlantic cutoff.
• "t850", "z850"

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•        : Geopotential + temperature at 850hPa  -  lower level conditions, detection of fronts
  

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Using either the hres_1x1.mv or hres_2x2.mv macro plot some of these other maps to study the synoptic development. Note for example that there should not be a strong horizontal temperature gradient around Nadine (why?) and the winds should be stronger for Nadine than the cutoff.

It would be instructive to view a cross-section through Nadine and the cutoff. Choose from the following (note the cross-section macro hres_xs.mv uses slightly different names for the parameters)

You do not need to plot all of these maps. Focus on what interests you and prepare some plots for group discussion.

Vertical structure

This part of the task is to look at cross-sections through Hurricane Nadine and the cut-off low.

Right-click on the icon 'hres_xs.mv' icon, select 'Edit' and push the play Image Addedbutton.

The plot shows the potential vorticity (PV), wind vectors projected onto the plane of the cross-section and potential temperature drawn approximately through the centre of the Hurricane and the cut-off low. The red line on the map of MSLP shows the location of the cross-section.

Changing forecast time

Cross-section data is only available every 24hrs.

This means the 'steps' value in the macros is only valid for the times:  [2012-09-20 00:00], [2012-09-21 00:00], [2012-09-22 00:00], [2012-09-23 00:00], [2012-09-24 00:00], [2012-09-25 00:00]

To change the date/time of the plot, edit the macro and change the line:

steps=[2012-09-22 00:00]

Changing fields

A reduced number of fields is available for cross-sections compared to the isobaric maps: temperature (t), potential temperature (pt), relative humidity (r), potential vorticity (pv), vertical velocity (w), wind-speed (speed; sqrt(u*u+v*v)) and wind vectors (wind3).

Choose from the following (note the cross-section macro hres_xs.mv uses slightly different names for the parameters).

Changing cross-section location

#Cross section line [ South, West, North, East ]
line = [30,-29,45,-15]

The cross-section location (red line) can be changed in this macro by defining the end points of the line as shown above.

Remember that if the forecast time is changed, the storm centres will move and the cross-section line will need to be repositioned to follow specific features. This is not computed automatically, but must be changed by altering the coordinates above.

For help on how to save images, see the beginning of this tutorial.

Task 2: Precipitation over France

Choose a hres macro to use, plot the total precipitation (parameter: tp), near surface wind field (parameter: wind10), relative humidity (parameter: r) (and any other parameters of interest).

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