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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. In this interesting case study, the HyMEX field campaign was also underway. We will see how the forecast products were used during this campaign.

This case study is based on the paper (recommended reading):  

Pantillon, F., Chaboureau, J.-P. and Richard, E. (2015), 'Vortex-vortex interaction between Hurrican Nadine and an Atlantic cutoff dropping the predictability over the Mediterranean,   http://onlinelibrary.wiley.com/doi/10.1002/qj.2635/abstract

 

Caveat

In practise many cases are aggregated in order to evaluate the forecast behaviour of the ensemble. However, it is always useful to complement such assessments with case studies of extreme events, like the one in this exercise, to get a more complete picture of IFS performance and identify weaker aspects that need further exploration.

Recap

ECMWF operational forecasts consist of:

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

Saving images and printing

 To save 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 command to take a 'snapshot' of the screen:

ksnapshot

 

Outline of the exercises

  • Study track & development of Hurricane Nadine and the N.Atlantic cut-off low
  • Study HRES & ENS forecasts of the time
  • Study HRES & ENS forecasts using the 2016 ECMWF ensemble forecast
  • .... PCA analysis ..
  • ...etc...

 

Starting up metview

Before starting metview, you may need to type a command to copy the exercise files to your user account.

Type the following command in a terminal window
metview

Please enter the folder 'openifs_2016' to begin working.

 

Exercise 1. The ECMWF analysis

 

Learning objectives

  •  Study development and behaviour of Hurricane Nadine
  • ...

Task 1: Hurricane Nadine

  • Plot and animate MSL + 500hPa maps showing track of Nadine
  • ...

 

 

Acknowledgements

 


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