[LMD in the field] MOSAI: Measuring surface-atmosphere interactions at the foot of the Pyrenees

August saw the second operation in the MOSAI (Models and Observations for Surface Atmosphere Interactions) project, in which the LMD is involved. It took place at the atmospheric research center at Campistrous at the foot of the Pyrenees. The photo shows a radio-sonde launch, as carried out four times a day for seven days. One of the aims of MOSAI is to use on-site observations to identify errors in climate models. In a preliminary approach, the atmospheric model developed at LMD coupled to the continental surface model (ORCHIDEE) is used in a “zoomed-nudged” configuration, to simulate near-surface variables observed at French sites. A visualization tool enables these simulations to be compared with those of other models participating in MOSAI and with observations, on relevant diagnostics (an example here). Another LMD contribution to MOSAI concerns the development of a parameterization of the friction exerted by the surface on the large-scale atmospheric flow, in the presence of small-scale terrain heterogeneities.

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