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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 

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Analyses (click image for full-size) Image Added Image Added Image Added Image Added MSLP, Z500 and track of Hurricane Nadine PV/320K and MSLP MSLP, 10m wind, Z500 & windspeed, SST Cross-section through Hurricane Nadine and cut-off low showing PV, theta and wind vectors. Illustrates warm core of Nadine and cold core of cut-off.

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HRES (deterministic) forecast   Image Added Image Added Image Added MSLP & T2m, Z200 & windspeed, equiv. potential temp., 850hPa wind & T Total precipitation Z500 difference between HRES & analysis

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Ensembles Image Added Image Added Image Added RMSE curves Z500 for ensemble MSLP ensemble mean and spread compared to analysis MSLP ensemble spaghetti plot Image Added Image Added Image Added Ensemble stamp map total precipitation over France Ensemble difference stamp map of z500 Comparing MSLP of perturbed ensemble member to analysis Image Added Image Added   Difference maps of two ensemble members to analysis Cumulative distribution function MSLP for ensemble forecast at Toulouse, France

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Principal component analysis and Clusters After computing the EOFs a clustering can be applied to all of the above ensemble plots. Image Added Image Added Image Added EOF and PCA analyses of ensemble spread for Z500 using clustering (top graph; clusters shown as either red or blue dots). Z500, ensemble mean of cluster 1 and 2 (top left & right respectively), compared to HRES & analysis bottom. Stamp difference map of MSLP with clusters enabled. Maps are ordered according to which cluster they are in Image Added Image Added Image Added Ensemble spaghetti plot with clusters. Top left and top right show ensemble members in cluster 1 & 2 respectively. Z500 RMSE curves with clusters. Ensemble members in each cluster are plotted separately. Stamp map of total precip. with clustering enable. Maps are ordered according to their cluster.

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Probabilities Two ensemble forecasts datasets were provided for the workshop. The 2012 operational ensemble and a reforecast using the operational ensemble of 2016. Image Added Probabilities of total precipitation greater than 20mm for both ensembles at 3 different forecast times.

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:

20120915 00Z (single start date), 10 days (to 20120925 00Z),  6hrly  (note start date for AN is different to forecasts)

If data size is an issue only use MSLP & T2m for 00Z 15th - 18Z 19th, with all fields from 20th to 25th.

For Gibraltar case:  2012092700 (2618 for rainfall?)

HRES:

20120920 00Z, 5 days (to 20120925 00Z), 6hrly, native grid

Also 2012092700 as analysis for Gibraltar case.

Same fields as analysis (see below)

Operational ensemble as used in 2012:

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

Also 2012092700 as analysis for Gibraltar case.

Same fields as analysis

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

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

Same fields as analysis

Uncertainty runs:

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

May not get time in workshop to look at these but 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/fields as above.

Grid resolution

Use native grid of analysis/forecasts if at all possible. Revise if total data is going to be more than 10Gb.

Fields : 

MSLP, T2m, 10m winds, 6hrly RR (rainfall rate), do we have this? If not, accum. total precipitation

SST : from analysis, HRES, oper. ensemble and expt:gioi (to compare)

200, 500, 700, 850 hPa : Geopotential, temperature,  potential temperature, equivalent potential temperature, winds (U/V), relative humidity (rather than sp. hum.),

600hPa only vertical velocity (waiting for confirmation want Pa/s or m/s)

850hPa only : absolute vorticity (not on any other levels)

925hPa additional winds & rel. humidity only (in addition to above levels)

PV + wind (U/V) @ 330 K isentrope (see Fig.10/13 in paper)

Vertical x-sections

Daily only (00Z)

Tropospheric pressure levels only (200hPa ->)

Fields: Temperature (potential temp. computed), potential vorticity, winds, relative humidity, vertical velocity.

An & all forecasts & all ensemble members (if space). Review if necessary.

Note plotting should handle winds normal to x-section.

Observational data

• if time and space only.

Data domain

Extract data similar to domain in figure 1 but suggest crop AN 15N - 65N / 20E - 60W (to capture Nadine track from 15th), FC 20N - 65N / 20E - 50W

Other data

Satellite images to be provided by ENM & included on VM. Due to licensing restrictions we can't provide the GRIB data on the VM.

Plots

Icons

• 1x1, 2x2
• Difference maps (an-fc, ens-control)
• stamp maps
• RMSE curves geopotential (500hPa), RMSE plumes
• spaghetti plots
• nadine track icon
• PCA (new)
  

Horizontal / isobaric maps

Students should do at least:

• MSLP + 10m winds / T2m + overlay with 850hPa absolute vorticity + overlay with 700hPa rel. humidity -> Signatures at low levels of Nadine and disturbance associated with the cutoff low.  Mid level humidity of the systems. 
  
• Geopotential + temperature at 500hPa --> mid-trop localization of the cold cutoff and warm Nadine. On the deterministic forecast we should not see Nadine and the cutoff 'meeting' with Nadine moving eastward.
• Geopotential + temperature at 850hPa --> lower level conditions, detection of fronts

• Equivalent potential temperature at 850 hPa  + winds at 850 hPa + vertical velocity at 600hPa + MSLP in background --> focussing on the moist and warm air in the lower levels and the vertival motion. There should not be a strong horizontal temperature gradient around Nadine, the winds should be stronger for Nadine than for the cutoff.

• 10meter winds + 6hourly RR + MSLP in background --> We should see an impact on the RR over France around t+108h (cf Pantillon fig 2)

• 330K potential vorticity (PV) + winds --> upper level conditions, upper level jet and the cutoff signature in PV, interaction between Nadine and the trough

Vertical x-sections

Vertical x-sections in the cutoff and in Nadine. Students should do at least:

• PV + winds (preferably normal winds) +  potential temperature --> to look at the cold core or warm core structure of the systems on the vertical and the signature in PV and winds.
• PV + relative humidity + vertical velocity --> a more classical x-section that we use to see if a PV anomaly is accompanied with vertical motion or not.

Q. How to plot ensembles? All ensemble members or cluster x-section?

From Frédéric: (15/Mar)

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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  (ENM to provide images to avoid licensing issues)
  
•  Extract data from the archive.
•  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

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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:

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