| Table of Contents | ||
|---|---|---|
|
Introduction
In these exercises we will look at a case study of the interaction between a Hurricane and Atlantic cut-off low in the context of ensemble forecasting. During the course of the exercises, we will explore the scientific rationale for using forecast ensembles, why they are necessary and how ensemble forecasts can be visualized. We will also use principle component analysis (PCA) and clustering to analyse the behaviour of the ensemble. In this interesting case study, the HyMEX field campaign was also underway. We will see how the forecast products were used during this campaign.
...
To plot upper level fields, specify the pressure level after the name. e.g. z500 would plot geopotential at 500hPa.
Some extra fields are also provided: vertical velocity at 700hPa (w700), relative vorticity at 850hPa (vo850) and potential vorticity at 320K.
Wind fields are normally plotted as coloured arrows. To plot them as wind barbs add the suffix 'f'. e.g. wind10f will plot 10m wind as barbs.
| Panel | |||||
|---|---|---|---|---|---|
| |||||
With the edit window open, find the line that defines 'plot1':
To add the 500hPa geopotential, change t |
- Plot and animate MSL + 500hPa maps showing track of Nadine
> 1 : Nadine MSLP and T2m (or better SST) tracking 15-20 september
> 2 : Satellite views on the 20th (provided by Etienne, if possible to put on the VM)
> 3 : Studying of the horizontal maps (analysis + forecasts)
> 4 : Studying and building of the vertical x-sections (analysis + forecasts)
Notes from Frederic: email 7/4/16
day 1
day 2
Change this line to:
|
As above, click the play button and then animate the map that appears.
Questions: TO DO
Task 3: Changing geographical area
Right-click the mouse button on the 'an_1x1.mv' icon and select the 'Edit' menu item.
In the edit window that appears
| Panel | |||||||
|---|---|---|---|---|---|---|---|
| |||||||
With With With |
Change, mapType=0 to mapType=1 then click the play button 
at the top of the window. Repeat using mapType=2 to see the smaller region over France.
These different regions will be used in the following exercises.
Animate the storm on this smaller geographical map.
Task 4: Wind fields, sea-surface temperature (SST) and satellite images
The 'an_2x2.mv' icon allows for plotting up to 4 separate figures on a single frame. This task uses this icon to plot multiple fields.
As before, right-click on the 'an_2x2.mv' icon and select the 'Edit' menu item.
| Code Block | ||||
|---|---|---|---|---|
| ||||
#Define plot list (min 1- max 4)
plot1=["mslp"]
plot2=["wind10"]
plot3=["speed500","z500"]
plot4=["sst"] |
Click the play button at the top of the window to run this macro with the existing plots as shown above.
Note that each plot can be a single field or overlays of different fields as in the an_1x1.mv macro.
Wind parameters can be shown either as arrows or as wind flags ('barbs') by adding 'f' to the end of variable name e.g. "wind10f".
Satellite images
Open the folder 'satellite' by doubling clicking (scroll the window if it is not visible).
This folder contains satellite images (water vapour, infra-red, false colour) for 00Z on 20-09-2012 and animations of the infra-red and water vapour images.
Double click the images to display them.
Use the an_1x1.mv and/or the an_2x2.mv macros to compare the ECMWF analyses with the satellite images.
Questions
Q. What do you notice about the SST?
TODO
Task 5: Cross-sections
The last task in this exercise is to look at cross-sections through the storm and
| Info |
|---|
This completes the first exercise. You have now learnt how to use the key macros, alter fields for plotting and animate fields. |
- Plot and animate MSL + 500hPa maps showing track of Nadine
> 1 : Nadine MSLP and T2m (or better SST) tracking 15-20 september
> 2 : Satellite views on the 20th (provided by Etienne, if possible to put on the VM)
> 3 : Studying of the horizontal maps (analysis + forecasts)
> 4 : Studying and building of the vertical x-sections (analysis + forecasts)
Notes from Frederic: email 7/4/16
day 1
day 2
I suggest to focus on the period before the 20-25 September and to study
Nadine and the cutoff, not yet at the impact o the Mediteranean area (we
leave that for later)
Agreed. The first exercise will be to examine the track & changes in the storm using the analyses.
I suggest to focus on the period before the 20-25 September and to studyAgreed. The first exercise will be to examine the track & changes in the storm using the analyses.
Nadine and the cutoff, not yet at the impact o the Mediteranean area (we
leave that for later)
Period : 0918-0920. If we want to look into a more intense Nadine (cat1As long as we have no concerns about the data size we can go back to the 15th. Do you have a preference?
Hurricane) we have to go back to the 15th.
Domain : I suggest to choose the same domain as in PantillonAgreed. The 'data domain' will be close to Fig.1 in Pantillon. The students will be able to use two 'plotting domains', one close to Fig1, the other close to Fig 2.
*1)* Is it possible to plot Nadine's very unusual track in Metview (seeYes, we can. I've got the track data and we can have an animation of variables (e.g. MSL, winds) along the display of the track. We have done similar for Hurricane Sandy.
attached file) ? Here are some additional useful links :
*2)* Metview Plots :
Can we propose satellite images in Metview ? Infrared and visible would
be perfect. As an extra Water vapor imagery ?This is tricky. We are not allowed to distribute GRIB files of satellite data. We can provide the images but then the students would not be able to overlay the maps. Leave this with us and we'll decide.
*Here are some inputs concerning Day2 and Nadine's study on day 2:
*1)* T1279 Analysis 0920 + t+96 deterministic forecast 0924 (t+96h) -->Agreed.
focusing on the interaction between Nadine and the cutoff. Maybe an
extra plot of the forecasted rainfall at t+96 over France ?
*2)* Ens T639 forecasts : I saw that T639 is the 2012 operational
ensemble resolution, so we will see the same bifurcation in the
scenarios as explained in Pantillon : the visualization of the spread,
the plumes, the spaghettis, ... will help here. I am sure you have great
ideas on this topic. Maybe we can propose some horizontal maps of each
(or some) members ?
I think the exercises we used last year will fit well here. I will start drafting the exercises on the wiki and ask you to help and comment.
I presume the exercises should be in English? Or should we do a side-by-side English/French version?
*3)* PCA and clustering : if you manage to put it in Metview this will
be great lo look at the 2 distinct patterns. I asked Florian Pantillon
his NCL sources to do the trick. I'll use it to build an extra NCL
exercice with PCA, clustering and compositing, if we have time. The file
format needed will be netcdf.
We think our PCA code can be used to reproduce fig 5. We thought we could also reproduce fig 6 but instead of dots plot the ensemble number. Then the students can build the clusters (Fig. 7) but grouping the ensemble members together?
We (here) need to try this and see how far we can reproduce the rest of the figures in the paper.
*4)* Ensemble runs : initial (EDA+SV) and model (SPPT+SKEB) : same as
last year
SST experiment might be too much, except if we shorten the ensemble study...
See above. My preference after talking with people here is to use the comparison between 2012 operational ensemble and 2016 operational ensemble. The lower res (T319) ensembles; control (EDA+SV), (SPPT_SKEB) ensembles for this case are running now and we can include the data (as long as filesize does not become an issue). But honestly, I do not think there will be time. I will leave it to you to decide!
We counted 7hrs total for the practicals (not including the SCM). Part of that time the students will need to prepare some plots for the discussion on Friday.
I am concerned about the time available. Perhaps my talk on weds 9.30-10 could be shortened to 15mins.
*Day 3
SCM experiments
...