Page History

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Fig8.1.4-2: 10-day medium-range meteogram for Oslo from Ensemble Control Forecast (ex-HRES) (blue line) and ensemble members (box and whiskers) data time 00UTC 26 June 2023.   The map shows a close up of Oslo city.  The nearest land grid point to central Oslo is at 59.93N 10.83E which lies some 5km away from and some 141m higher than Oslo city centre.  This grid point may well be representative of Haugerud on the fringes of Oslo, but temperatures are reduced to near sea level using 5.5K/km lapse rate.

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• An inland location - Newport (location N).  The ensemble grid is scanned for the grid points surrounding the location (ensemble grid points NPJR) and the nearest land point is chosen (Point J).  This is a land point where the "fraction of land cover" is 100% and the surface energy fluxes are determined by HTESSEL.
• A coastal city location - Portsmouth (location P).   The ensemble grid is scanned for the grid points surrounding the location (ensemble grid points ABCD) and the nearest land point is chosen (Point A).  This is a land point where the "fraction of land cover" is 100% and the surface energy fluxes are determined by HTESSEL.  There will be no influence of a water surface.  HTESSEL does not take into account the urban nature of the city. 
• A coastal location - Freshwater (location F).  The ensemble grid is scanned for the grid points surrounding the location (ensemble grid points MNRS) and the nearest land point is chosen (Point R).  This is a land point where the"fraction of land cover" is 60%-70%.  Surface  Surface energy fluxes are determined 60%-70% by HTESSEL and 30%-40% by FLake.
• A coastal location - Bembridge (location B).  The ensemble grid is scanned for the grid points surrounding the location (ensemble grid points EFGH).  None is a land point and a sea point is chosen (Point E).  At this point the "fraction of land cover" is less than 50% and the surface energy fluxes are determined by FLake.  There will be no influence of land energy fluxes.  In fact any land location within grid box EFGH will be treated similarly, no matter how far away from the coast. 
• A coastal location - Ventnor (location V).  The ensemble grid is scanned for the grid points surrounding the location (ensemble grid points JHLK) and the nearest land point is chosen (Point J).  This is a land point where the "fraction of land cover" is 100% and the surface energy fluxes are determined by HTESSEL.  No adjustment is made for the influence of the sea and the effect of the sea may not be evident on ensemble meteograms.  This grid point is the same as selected for the inland town of Newport (location N) even though the town of Ventnor (location V) is right on the coast. 
• A location near land - offshore of Ventnor (location S).  The ensemble grid is scanned for the grid points surrounding the location (ensemble grid points JHLK) and the nearest sea point is chosen (Point L).  The surface energy fluxes are determined by FLake.  The influence of the sea will be more evident on ensemble meteograms for location S than at location V. 

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Fig8.1.4.1-5: 10-day medium-range meteogram for Vevey (on the shores of Lake Geneva) from Ensemble Control Forecast (ex-HRES) (blue line) and ensemble members (box and whiskers) data time 00UTC 26 June 2023.   The nearest land grid point to Vevey is at 46.50N 6.79E which lies some 5km away from and some 281m higher than Vevey city centre.  This grid point may well be representative of the mountains to the northeast of Vevey, but temperatures are reduced to Vevey level using 5.5K/km lapse rate.

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Fig8.1.4.1-6: 10-day medium-range meteogram for Montreaux (on the shores of Lake Geneva) from Ensemble Control Forecast (ex-HRES) (blue line) and ensemble members (box and whiskers) data time 00UTC 26 June 2023.   The nearest land grid point to Montreaux is at 46.43N 6.92E which is almost coincident with the city.  However, the model altitude is some 219m higher than Montreaux city centre.  Temperatures are reduced to Montreaux level using 5.5K/km lapse rate.

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Fig8.1.4.1-8: 10-day medium-range meteogram for Santa Cruz de Tenerife from Ensemble Control Forecast (ex-HRES) (blue line) and ensemble members (box and whiskers) data time 00UTC 26 June 2023.   The nearest land grid point to Santa Cruz is at 28.51N 16.28W which lies some 5km away from and some 173m higher than Santa Cruz.  This grid point may well be representative of the hills to the northeast of Santa Cruz, but temperatures are reduced to Santa Cruz level using 5.5K/km lapse rate.

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Fig8.1.4.1-9: 10-day medium-range meteogram for Mount Tiede from Ensemble Control Forecast (ex-HRES) (blue line) and ensemble members (box and whiskers) data time 00UTC 26 June 2023.   The nearest land grid point to Mount Tiede is at 28.30N 16.63W which is almost coincident with the mountain peak.   However, the model altitude is some 1408m lower than the height of the mountain.  Temperatures are corrected to mountain peak level using 5.5K/km lapse rate.

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There are wide variations in orography within the islands (the islands are quite mountainous) and the representativeness of a grid point can be uncertain.  Local uncertainty in forecast temperatures at altitude can have a large impact of model precipitation especially over mountainous islands and coasts.  

Example4: Isolated small islands.

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Fig8.1.4.1-11: 10-day medium-range meteogram for the town of Malfa on Malfa Island from Ensemble Control Forecast (ex-HRES) (blue line) and ensemble members (box and whiskers) data time 00UTC 26 June 2023.   The ensemble grid is scanned for the grid points surrounding the location.  None is a land point and nearest sea point is chosen.  This point is actually situated on land but the "fraction of land cover" is less than 50% and the surface energy fluxes are determined by FLake.  There will be no influence of land energy fluxes.  In fact the whole island including the mountains will be treated similarly, no matter how far away from the coast.  This grid point may well be representative of the southwest coast of the island.  However, local effects may be important on other coasts (e.g. sea breezes).  Conditions at inland high ground will not be reliably indicated, particularly for Monte dei Porri which rises to 860m.   

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Fig8.1.4.1-12: 10-day medium-range meteogram for the town of Stromboli on Stromboli Island from Ensemble Control Forecast (ex-HRES) (blue line) and ensemble members (box and whiskers) data time 00UTC 26 June 2023.   The ensemble grid is scanned for the grid points surrounding the location.  None is a land point and nearest sea point is chosen.  There will be no influence of land energy fluxes.  In fact the whole island including the mountains will be treated similarly, no matter how far away from the coast.  Local effects may be important (e.g. sea breezes).  Conditions at inland high ground will not be reliably indicated.   

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Fig8.1.4.1-13: 10-day medium-range meteogram for the Stromboli volcano on Stromboli Island from Ensemble Control Forecast (ex-HRES) (blue line) and ensemble members (box and whiskers) data time 00UTC 26 June 2023.   The ensemble grid is scanned for the grid points surrounding the location.  None is a land point and nearest sea point is chosen.  There will be no influence of land energy fluxes.  In fact the whole island including the mountains will be treated similarly, no matter how far away from the coast.  Conditions at inland high ground will not be reliably indicated.  Note the temperature data at the sea grid point (model height -8m due to the spectral representation of altitude) is amended to that at 422m (the model height at Stromboli volcano) which is itself less than the true geographic height of 926m.    

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