Moisture regime at the surface

Figures 3d shows the soil saturation specific humidity (noting that C/sat ~ f"xal ), the air specific humidity and theirdifference (qa* rj, between the perturbed and the control simulations in the Bernese Alps glaciers and transition zone during February 27, 1990. During that day, the air near the surface exhibits a moisture excess over glaciers of and over the transition zone on average compared to the control simulation. The saturation specific humidity is always lower over glaciers {Aqsai = -0.05 gkg"1), but over the transition zone it is generally lower during the day and higher during the night, the daily average being slightly negative, Aqsa, = -0.03 g kg"1. Their differences are usually negative on a daily average (A(qsal-which imply that the vertical saturation deficit has increased in magnitude. Compared to the control integration in the Bernese Alps, the evaporation (deposition) has decreased over glaciers (AES = 6.\ mm d"1) but only slightly over the transition zone (AE, = 0.5 mm d"1). The precipitation (solid) decreased over glaciers (AP, = -3.7 mm d"1) and over the transition zone (APS = -1.6 mm d"1) compared to the control simulation. The difference averaged over the day in the Bernese Alps is a slight deficit compared to the control simulation over glaciers and transition zone. Snow accumulation on the ground has thus decreased in the Bernese Alps compared to the control simulation, about AMS - -5.6 kg m"2 (-1.4 cm) over glaciers, and AMs = -\3 kgm"2 (-0.4 cm) in the transition zone on average during the day. Both simulations produced the same value of the soil moisture: the normalised moisture variable, w, shows that there is no liquid phase present throughout the day and the solid phase remains at 0.9 of their respective capacity. Since the soil is not saturated with water on average during the day, it is presumed that the runoff may be neglected.

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