Abstract : 1C.4
Local climate of Ardeche mires

Fabrice Grégoire
Fabrice.Gregoire@ens-lsh.fr
Ens-Lsh Umr 5600

In order to complete Meteo-France data at a local scale for mires water management, it has been decided with their naturalist manager (CREN Rhône-Alpes) to set two climatologic stations on two mires situated on the Ardèche plateau, east border of Massif Central. The main reason is that, in this aera, amount of precipitations, very important for mires water balance, exhibits a huge variability within a few kilometers. Other reason is that mires have their own microclimate.

We measure a few parameters with a simple device for three reasons :

- we don’t intend to make highly fondamental researches, but to collect data for real use and complete observations of better equipped mires sites,

- data collect and station management must be easy for non specialists, such as naturalists,

- cost has to be low, at the level of manager finances

The two stations measure temperature in a miniature meteorological shelter and precipitations via a rain gauge which is not well suitable for snow measurement. It would be very useful to have local measures of evapotranspiration, for there is only one Meteo-France station for this parameter on the whole plateau, but it was too expensive.

In addition there are two piezometric recorders.

The two sites are completely different. The first one, Sagne Redonde (Lanarce), is a maar bottom mire, at 1230 meters high. The second one, Montselgues, is a gathering of tiny mires very close to the top of a 1000 meters high spur.

First results confirm the interest of this local setting :

The Sagne Redonde is a true frost hollow where air temperature minima can be lower by 10°C compared to other plateau stations, while rain amount is not very different.

The Montselgues mires have air temperatures very similar to Meteo France references, but annual precipitations are lower by 25% compared to the nearest Meteo France station.

Piezometric reactions are also very different.