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Selection of grid points for meteograms and vertical profiles

For a specific location, the appropriate grid point data for meteograms or vertical profiles are selected in different ways.  This can lead to inconsistencies in forecast surface temperatures.

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Other influences regarding forecast 2m temperatures also have an impact.

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Fig9.9-1: Selection of grid points for meteograms.  Consider the four ensemble grid points that surround a location of interest.  If there is at least one land grid point within these four, then the nearest land point will be chosen regardless of distance. This means that meteograms at some coastal locations may not reflect the effects of the nearby sea.  If only sea points are available then the nearest sea grid point will be chosen, even if the location lies over land, and may not reflect the effects of the land.  Dots represent grid spacing of 9km. The colour scale represents the proportion of heat, moisture and momentum for each grid point derived by HTESSEL and Flake at 9km resolution. 

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Fig9.9-2: Selection of grid points for vertical profiles.  Consider the four ensemble grid points that surround the location of interest.  The nearest grid point will be chosen regardless of being land or sea grid point. This means that vertical profiles at some coastal locations may not reflect the effects of the nearby sea or may not reflect the effects of the land.  Crosses represent grid spacing 0f 18km.  The colour scale represents the proportion of heat, moisture and momentum for each grid point derived by HTESSEL and Flake at 9km resolution. 

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Fig9.9-3: Comparing the selection of grid points for meteograms and vertical profiles at various locations derived from Figs 9.9-1 and 9.9-2 above.  There can be significant differences in near surface temperatures and can have consequences regarding destabilisation.  Diurnal temperature ranges shown on meteograms might be greater than shown on vertical profiles or may not be captured at all where a sea grid point lies over land.

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Dots represent grid spacing of 9km. The colour scale represents the proportion of heat, moisture and momentum for each grid point derived by HTESSEL and Flake at 9km resolution.

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Fig9.9-4: An example of differing forecast 2m temperatures given by meteogram and vertical profile using the processes outlined above.  Consider Bournemouth (X^BH):

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