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Fig9.9.4: An example of differing forecast 2m temperatures given by meteogram and vertical profile using the process processes outlined above.  Consider Bournemouth (X^BH):

• The meteogram For meteograms, the selection process 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  In this case diurnal effects and energy flux over land give a forecast temperature 2m of 22C.
• The vertical profile For vertical profiles, the selection process 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 the energy flux from the sea exclusively.  It does not use any energy flux from the land though this is in close proximity.  Fairly  In this case fairly constant energy flux over sea gives a forecast 2m temperature of 19C. 

The chart is a section of the charts above and the data 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 there is complex coastal or mountainous geography (e.g. Norwegian coast).  Even a marked contrast in land surfaces can have an effect.

(FUG Associated with Cy49r1)  

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