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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 process outlined above.  Consider Bournemouth (X^BH):

• The meteogram scans the four grid points (DEFG) surrounding the location, and chooses the nearest land point (E) even though sea point (D) is closer.  Thus the meteogram uses energy flux from the land exclusively but at a location remote from the location of interest.  It does not use any energy flux from the sea though this is in close proximity.  Diurnal effects and energy flux over land give a forecast temperature 2m of 22C.
• The vertical profile scans the four grid points (ABCD) surrounding the location, and chooses the nearest point (D) irrespective of whether it's a land or sea point.  Thus the vertical profile uses energy flux from the sea exclusively.  It does not use any energy flux from the land though this is in close proximity.  Fairly constant energy flux over sea gives a forecast 2m temperature of 19C. 

The chart is a section of the charts above and is for T+36 VT 12UTC 25 Aug 2025 DT 00UTC 24 Aug 2025.   The wind arrows are only shown to indicate the location of grid points at 9km resolution although some advection of boundary layer air is forecast moving from sea to land.  The land/sea distribution governs the proportion of energy flux from land or sea at each grid point (coloured as above).  

The differences in forecast temperature can be magnified at some coastal locations where the sea and land energy fluxes are very different (e.g. Gulf of Bothnia or  Arabian Gulf) or where complex coastal or mountainous geography.

(FUG Associated with Cy49r1)  

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