| ABSTRACT | Modelling temperature distribution and recent warming along the Mediterranean coast and its mountains inland : the extreme south-eastern French area case.The extreme south-eastern France includes French Southern Alps and the more southern area to the seaside which is usually considered as belonging to Mediterranean climate (Urban Heat Islands being excluded).1 Temperature topoclimatological modelling Topoclimatological temperature modelling relies on the influence of topographic settings (slopes, summits or valleys) and of slope expositions (south or north). It is based on linear relations between temperature with altitude for each topoclimate and concerns all the altitudes. It has led to prove that the whole area is divided, from the point of view of temperature, into two regions, the whole Inland represented by the same linear regressions and a small irregular line along the coast (Douguedroit, 2018).Three main groups of topoclimate regressions have been computed for the Inland for the 2011-2017 period : South-facing slopes (SFS), Valley bottoms and bassins (VBB) and Tops (T). Mean annual temperature (MT) range at 2 meter high at sea level between SFS and VBB averages at 1°C (16.7-15.7 at sea level) due to differences (0.5°C) in Maximum (MaxT) and above all (1.6 °C) in night Minimum (MinT). Differences in MaxT is due to slope exposition to solar radiation and in MinT to the cold air sliding down on the slopes but stagnating in the bottoms. Tops present MaxT similar to SFS values but higher for MinT.The MT of MaxT of the Littoral is lower than both MaxT of SFS and VVB in the Inland (21.0°C) and the MinT is higher (12.4°C), due to the physical difference between earth and sea temperature variations between day and night. Temperature variations on the Littoral are closely linked with those of the Mediterranean Sea. This temperature distribution model dividing areas close to seas into Inland and Littoral can be applied around the Mediterranean and other seas. 2 Warming between 1959-65 and 2011-17.Results are based on the comparison between the same topoclimates during both periods but not between the same stations (less than half are common). The short duration of each period is due to the limited number of stations available in the mid of the last century.Inland, ranges of the SFS and the VBB MT are 0.6°C and 0.7°C, due in both cases to the MaxT means (up to +1.2°C for both topoclimates) and only +0.1°C for the MinT. Such a difference between day and night (similar in the Swiss Jura) looks as if recent modifications in the atmosphere only influence warming when sun shines.On the Littoral MT increase is 1.8°C (+1.6°C during day and +2.0°C during night) to be compared with the increase of sea temperature.Difference in warming between day and night has not yet been explained.Douguedroit A., 2018, Modélisation du réchauffement des Alpes du sud à la Mer Méditerranée XXIè colloque de l’A.I.C. Les échelles temporelles fines. Nice, 4-7 juillet 2018, 175-282. |