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In 2012, at the time of this case study, ECMWF operational forecasts consisted of:

  • HRES : spectral T1279 (18km 16km grid) highest resolution 10 day deterministic forecast.
  • ENS :   spectral T639 (34km 31km grid) resolution ensemble forecast (50 members) is run for days 1-10 of the forecast, T319 (70km) is run for days 11-15.

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Info

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?


Warning
titleClose unused plot windows!

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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titlePlot PV at 320K

Change the value of "plot1" again to animate the PV at 320K.

Code Block
plot1=["pv320K"]

You might add the mslp or z500 fields to this plot e.g.

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

Note that the fields are plotted in the order specified in the list!

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titleQuestions
Q. When does the cut-off low form (see z500)?
Q. From the PV at 320K (and z500), what is different about the upper level structure of Nadine and the cut-off low?

Task 3: Changing the map geographical area

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The ECMWF operational deterministic forecast is called HRES. At the time of this case study, the model ran with a spectral resolution of T1279, equivalent to 18km 16km grid spacing.

Only a single forecast is run at this resolution as the computational resources required are demanding. The ensemble forecasts are run at a lower resolution.

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  • "vo850", "mslp"               : vorticity at 850hPa and MSLP  -  low level signature of Nadine and disturbance associated with the cutoff low.
  • "r700", "mslp",         : MSLP + relative humidity at 700hPa  -  with mid-level humidity of the systems.
  • "pv320K", "mslp"     : 320K potential vorticity (PV) + MSLP  -   upper level conditions, upper level jet and the cutoff signature in PV, interaction between Nadine and the cut-off low.
  • "wind850", "w700"     : Winds at 850hPa + vertical velocity at 700hPa (+MSLP) : focus on moist and warm air in the lower levels and associated vertical motion.
  • "t2", "mslp"              : 2m-temperature and MSLP - low level signature of Nadine and temperature.
  • "mslp", "wind10"      : MSLP + 10m winds  -   interesting for Nadine's tracking and primary circulation.
  • "t500","z500"          : Geopotential + temperature at 500hPa  -  large scale patterns, mid-troposphere position of warm Nadine and the cold Atlantic cutoff.
  • "eqt850eqpt850", "z850"        : Geopotential + equivalent potential temperature at 850hPa  -  lower level conditions, detection of fronts.

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If your cluster definition file is called 'ens_oper_cluster.example.txt', then Edit cluster_to_anref.mv and set:

Code Block
languagebash
#ENS members (use ["all"] or a list of members like [1,2,3]
members_1=["cl.example.1"]
members_2=["cl.example.2"]

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Q. What do the EOFs plotted by eof.mv show?
Q. Change the parameter used for the EOF (try the 'total precipitation' (tp) field). How does the cluster change?

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