Facilities

Language

English used predominantly.

English teachers will be there. Encourage students to write and speak in English as students have asked for more lessons in English.

Tutorial: write in English

Travel & local arrangements

ENM is approx 20mins by car from the airport.

Topic

Storm Nadine. Case interaction between Hurricane Nadine and cut-off low, ensemble uncertainty & severe weather over France.

Paper: Pantillon, F., Chaboureau, J.-P. and Richard, E. (2015), Vortex–vortex interaction between Hurricane Nadine (2012) and an Atlantic cut-off dropping the predictability over the Mediterranean. Q.J.R. Meteorol. Soc.. doi: 10.1002/qj.2635 http://onlinelibrary.wiley.com/doi/10.1002/qj.2635/abstract 

Sensitivity - two main issues : Model resolution - to model interaction of the storm and cut-off low;  Convection processes.

Linus says ensemble is sensitive to SST. This particular case was in fact used as part of the argument for coupling the ocean model (NEMO) from day 1 in the ensemble forecast rather than day 10 as used in 2012; days 1-9 used persisted SST anomalies.

Datasets

From last year's workshop, each field ~ 100Kb. Total size of 'data' and 'data_ls' directories was:5.5G, 1.4G respectively , total of 7Gb.

2015 workshop VM, df reports 40Gb /, 28% used (27G)

Priority is the analyses, oper ens & expt gioi

Analyses:

T1279L137 20120915 00Z (single start date), 10 days (to 20120925 00Z), 3hrly? (if not 6hrly)  (note start date for AN is different to forecasts - if starting from 15th Sept is too much, start from 18th)

Operational ensemble as used in 2012:

TL639L91. 20120920 00Z (single start date), 5 days (to 20120925 00Z), 3/6hrly? (all members)

Current operational ensemble (with NEMO on day 1) (expt id: gioi)

TCo639L91. 20120920 00Z (single start date), 5 days (to 20120925 00Z), 3/6hrly (all members)

Uncertainty runs:

TL319L91. No NEMO coupling, wave model off (OpenIFS config)

May not get time in workshop to look at these but Frédéric would like to have the data available.

(a) EDA/SV/SPPT/SKEB - exptid 'gik3'

(b) EDA/SV only - exptid 'gin5'

(c) SPPT/SKEB only - exptid 'gin7'

Dates/steps as above.

Grid resolution (post-processed)

Needs to be good enough to resolve Hurricane Nadine in the plotting. What did we use last year?

Fields : 

MSLP, T2m, 10m winds, 6hrly accum. total precipitation

Geopotential, temperature,  potential temperature & equivalent potential temperature, winds (U/V), relative humidity (rather than sp. hum.),  @ 200, 500, 700, 850 hPa, also 925hPa for winds & humidity only (not sure if this is archived?)

PV + wind (U/V) @ 330 K isentrope (see Fig.10 in paper)

Geopotential/winds at 2PVU (do we archive these?)

Vertical x-sections

Potential temperature, potential vorticity, winds, humidity, vertical vel. -- needs reviewing, would need all pressure levels & will be too much data? PV + winds would be priority.

Request is for: all levels for : PV, winds, vertical velocity (if poss), rel. humidity, potential temperature (last two if space permits).

Suggest: if data size is a problem, omit the reduced resolution uncertainty runs.

Good if students could use metview to plot x-section through centre of storm, finding the storm centre themselves, perhaps modifying macros themselves ?

If too much data, make the full level data only available at specific times (e.g. daily). Failing that pre-plot images.

Tephigrams

Useful for the students to compare with Emagrams.

Which location(s)?

Model or obs?

We could pre-plot these as this is not particularly interactive.

Observational data

• possibly synop data to add to plot similar to fig2?

Data domain

Extract data similar to domain in figure 1 but suggest crop 50W - 20E / 30N - 65N (adjust to suitable aspect ratio)

Other data

- poss. satellite imagery

Plots

To be completed (but very similar to 2015 workshop)

Usual plots

- 1x1, 2x2

- Difference maps (an-fc, ens-control)

- stamp maps

- RMSE curves geopotential (500hPa), RMSE plumes

- spaghetti plots

Horizontal / isobaric maps

MSLP + 10m winds / T2m -> interesting for tracking Nadine & primary circulation

Geopotential height + temperature at 500hPa --> large scale patterns, position of Nadine's low and the Atlantic cutoff

Geopotential heigth + temperature at 850hPa --> lower level conditions, detection of fronts

1.5 PVU geopotential + winds or 330K potential vorticity (PV) + winds --> upper level conditions, upper level jet and the cutoff signature in PV

If space is an issue, decide which plots are to be interactive and which are available as images only.

PCA in Metview - speak to Linus (he says he has some Fortran code). Or could use R

Try to reproduce the plots in the article. 

• HRES & analysis only. Perhaps ECMWF ensemble? (modified ensemble in later task).

Plots that summarize the situation, focused on the study of Nadine and the cutoff (horizontal maps and vertical cross sections) and maybe a plot of the rainfall over France.

From Frédéric: (15/Mar)

5. SCM: I have the radiation exercices and convection exercices from previous workshops. It could be nice to look at the convective tendencies in Nadine's deep convection to illustrate of the convection scheme works. I am sure Peter Bechtold has great ideas about that !

On the second day, François Bouttier can also speak about optimal tresholds to use in order to deal with extremes with convective scale ensembles.

GC: It would be good to add something on this into the exercises?

Notes from Frédéric: (9/Feb)

I just spoke to a colleague of mine teaching statistics. He told me that our second year students that will attend the workshop will have knowledge in PCA and clustering methods via ascending hierarchical classification (with R)

So I think that on Day 2, it would be nice to make them do the PCA for ECMWF t+96 ensemble forecasts (20120920 analysis and forecast for the 20120924, figure 5 of Pantillon), the ascending classification (figure 6) and the clustering (figure 7). We could leave the classification and the clustering as extra questions, to leave room for the stochastic ensemble, the EDA and the class ensemble.

I will also think about the interesting plots that we could do to illustrate this case, for example vertical crosssection of potential vorticity.

TODO

• Decide on forecasts for workshop: resolution, start date(s) and forecast length : all runs start 00UTC 20 Sept 2012
• Decide what to do about provision of satellite imagery (or not - issues iwth licensing)
  
• Extract HRES & analysis
• Run ensemble forecasts
• Book accommodation
• Install SCM on OpenIFS VM
• Get PCA code from Linus & try it
• Get USB sticks from comms
• Frédéric to check last year's VM will run on classroom PCs and ensure VirtualBox (or VMware) is installed.
• Check for observations we might have in the archive for HYMEX that could be used

Notes

SCM exercises - sensitvity of the model to changing physics. Focus on convection, initiation of deep convection. Stochastic physics, impact on convection? impact of convective scheme?

Can we get observations from HyMEX to add to the metview exercises?.

Try to include some Hymex observations in metview VM?

Some questions to include:

• how to weight extreme events in the ensemble?
• what's the best way of doing ensembles if dont' want to miss extremes?