Case studies
Storm Xaver
On the 5 December 2013 a large and violent cyclonic storm hit the North Sea region and several adjacent countries. Problems were caused both by the high wind speeds and the related storm surge. The surge reached 6 metres in Hamburg for example and was the highest along the England east-coast for 60 years. In the aftermaths of the cyclone a blizzard hit Sweden. The storm system was named Xaver by Berlin's Free University; other names assigned elsewhere include Bodil, Sven and St. Nicholas (Hewson et al., 2014). T he cyclone developed around 00 UTC on 4 December northeast of Newfoundland and it was situated between converging northerly and southerly airstreams. Due to the westerly wind jet accelerated by the convergence, the cyclone moved to northeast and east, deepening explosively. It had an intense meso-vortex hanging back to west, which enhanced the strong wind (see Figure 1). The cyclone was presented in the operational forecasts 8-9 days before the event and the forecasts indicated the very strong wind gust 3-4 days in advance. (Although some strength overestimation over Germany as well as timing error in surface pressure were concluded.)
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Figure 1: 24-hour maximum wind gust (m/s) on 5 December with mean sea level pressure (white contours; hPa) on 12 UTC on 5 December from the operational forecasts at 00 UTC on 3 (left) and 5 December (middle) and from the observations (right). | ||
Storm Desmond
Storm Desmond caused severe flooding, travel disruption and a power outage across northern England, parts of Scotland and Ireland on 5 December 2015. Cumbria in northwestern part of England is one of the worst affected regions with more than 200 mm of rain in 24 hours recorded in that area. Storm Desmond broke the United Kingdom's 24-hour rainfall record, with 341.4 mm of rain falling in Honister Pass, Cumbria. On Saturday, 5 December, UK Met office issued a red warning of heavy rain for Cumbria. The cyclone also led to flooding in southern Norway.
Orographical enhancement of precipitation played a major role in the event and the operational model of the ECMWF picked well the highest rainfall amounts over the orographical barriers. However, the forecast underestimated the peak values of about 100 mm in 24 hours in Cumbria and overestimated the precipitation amount in lee of the hills (Figure 2).
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Figure 2: 24-hour precipitation amount (mm) between 6 UTC on 5 December and 6 UTC on 6 December, based on ECMWF operational IFS forecast at 00 UTC on 5 December (left, with cyan contours for the mean sea level pressure at 12 UTC on 5 December) and observations (right). | |
Model experiments
Several experiments have been conducted with OpenIFS for both cases with the aim to test the effect of starting date and forecast length, initial condition as well as spatial resolution to the forecast quality. The details of experiments are summarized in Table 1.
Table 1: Settings of the experiments achieved for Storm Xaver and Storm Desmond. | |||||||
| Experiment ID | Initial condition | Resolution | Starting date | Time step | Output frequency | ||
|---|---|---|---|---|---|---|---|
Xaver | 1. | ERA-Interim | T255L91 | 1 Dec 2013 | 2700 s | 3h | |
| 2. | ERA_Interim | T639L137 | 900 s | 3h | |||
| 3. | ERA5 | T255L91 | 2700 s | 3h | |||
| 4. | ERA5 | T639L137 | 900 s | 3h | |||
| line | |||||||
Desmond | 1. | gryg | ERA-Interim | T255L91 | 1 Dec 2015; 2 Dec 2015; | 2700 s | 3h |
| 2. | gs22 | ERA-Interim | T639L137 | 3 Dec 2015; 4 Dec 2015 | 900 s | 3h | |
| 3. | gs23 | ERA-Interim | T1279L137 | 3 Dec 2015; 4 Dec 2015 | 600 s | 3h | |
| 4. | gs0c | ERA5 | T255L91 | 3 Dec 2015; 4 Dec 2015 | 2700 s | 3h | |
| 5. | gs04 | ERA5 | T639L137 | 3 Dec 2015; 4 Dec 2015 | 900 s | 3h | |
!! The input data and the namelists needed to run the experiments can be downloaded from the ECMWF FTP server: download.ecmwf.int/openifs/evalution. !!
The files are packed in .tgz files and structured into directories named after the case studies (i.e., Xaver_201312, Desmond_201512) and subdirectories indicating the main experiment characteristics (e.g., T255L91_ERA5). The archive files were prepared by starting dates (e.g., gs0c_2015120300.tgz). Typical content of a .tgz file is as follows:
Size File name Description
0 2015120300/
: directory for a given starting date
0 2015120300/ecmwf/ : subdirectory containing the namelists and some outputs
4750 2015120300/ecmwf/namelistfc : namelist with detailed experiment setup
3983964 2015120300/ecmwf/NODE.001_01.model.1
: text output (log) file including all the important information about the model run
26563 2015120300/ecmwf/ifs.stat.model.1 : information about model steps (useful for debugging)
3161 2015120300/ecmwf/wam_namelist : namelist of the coupled wave model
3161 2015120300/ecmwf/wam_namelist_coupled_000 : namelist of the coupled wave model
9763008 2015120300/ICMCLgs0cINIT : input file containing surface and soil information (albedo, soil temperature etc.)
7311120 2015120300/ICMGGgs0cINIT : input file containing gridpoint surface initial data
36695160 2015120300/ICMSHgs0cINIT : input file containing initial data for the prognostic variables in spectral representation
106044120 2015120300/ICMGGgs0cINIUA : input file containing initial data for the prognostic variables in gridpoint representation
54997789 2015120300/wam_grid_tables : model grid and tables for the wave model
13000184 2015120300/wam_subgrid_0 : information for model advection, including sub-grid parametrisation for the wave model
26709432 2015120300/wam_subgrid_1 : information for model advection, including sub-grid parametrisation for the wave model
26709416 2015120300/wam_subgrid_2 : information for model advection, including sub-grid parametrisation for the wave model
64560 2015120300/cdwavein : initial value of drag coefficient for the wave model
7943760 2015120300/specwavein : initial wave spectra for the wave model
64560 2015120300/uwavein : initial value of wind speed for the wave model
2349600 2015120300/sfcwindin : initial value of 10-meter horizontal wind components and sea ice fraction for the wave model
To run OpenIFS, the files highlighted above in green colour are needed, i.e., the initial conditions for the atmospheric model (files with ICM) and the namelist (namelistfc). The namelist contains the necessary settings, e.g., the experiment number, the time step, the post-processing variables.
&NAMDYN
TSTEP=2700.0,
/
&NAMIOS
CFRCF="../rcf",
CIOSPRF="../srf",
/
&NAMFPG
NFPLEV=91,
NFPMAX=255,
/
&NAMCT0
LNHDYN=false,
NCONF=1,
CTYPE="fc",
CNMEXP="gs0c",
/
&NAMFPC
CFPFMT="MODEL",
NFP3DFS=5,
NFP3DFP=7,
NFP3DFT=1,
NFP3DFV=1,
MFP3DFS(:)=130,135,138,155,133,
MFP3DFP(:)=129,130,135,138,155,157,133,
MFP3DFT=60,
MFP3DFV=133,
NFP2DF=2,
MFP2DF(:)=129,152,
NFPPHY=89,
MFPPHY(:)=31,32,33,34,35,36,37,38,39,40,41,42,44,45,49,50,57,58,59,78,79,129,136,137,139,141,142,143,144,145,146,147,148,151,159,164,165,166,167,168,169,170,172,175,176,177,178,179,180,181,182,183,186,187,188,189,195,196,197,198,201,202,205,206,208,209,210,211,235,236,238,243,244,245,229,230,231,232,213,212,8,9,228089,228090,228001,260121,260123,228129,228130,
NRFP3S(:)=1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,
RFP3P(:)=100000.0,92500.0,85000.0,70000.0,50000.0,40000.0,30000.0,25000.0,20000.0,15000.0,10000.0,7000.0,5000.0,3000.0,2000.0,1000.0,700.0,500.0,300.0,200.0,100.0,
NFPCLI=0,
LFPQ=false,
LTRACEFP=false,
RFPCORR=60000.,
/
More information about the namelist settings can be found in the how-to articles : How to control OpenIFS output.
Post-processing
- how to prepare data for plotting
Metview macros
- where they are, how to set them up .. etc
Catalogue
References
Hewson, T. , Magnusson, L. , Breivik, O. , Prates, F ., Tsonevsky, I. , de Vries, H.J.W. , 2014: Windstorms in northwest Europe in late 2013. ECMWF Newsletter 139, 22–28. [PDF]