Figure 1. Mean annual number of subzero (<17.8C) days occurring during the period 195180, from NOAA (1982)

50 N

0

500 km

Figure 1. Mean annual number of subzero (<17.8C) days occurring during the period

195180, from NOAA (1982). The Canadian data were provided by D. Phillips, AES,

Downsview, Ontario. The study area of Figure 3 lies along the Connecticut River near Z.

Figure 2. Comparison of 07LCL(12UT)

X

temperatures observed at Mt. Washington

and Piermont, New Hampshire, during the

25

X

winter 199192. The station circles denote

snow cover at Z; the wind barbs denote

30

wind speed (5 m/s per barb) and direction

Mt. Washington Summit Temperature (C)

at Mt. Washington.

produced by the radiational heat loss at the snow/

Magono et al. (1982). Namias (1985) suggested

air interface. The magnitude of this decoupling

synoptic scale influence of snow cover on tem-

effect may be influenced by local features, caus-

perature and precipitation. Dewey (1977) showed

ing some of the observed variation in local tem-

that the presence of snow cover locally influenced

perature.

daily maximum and minimum temperature.

There are many examples in literature of dimi-

Longley (1949) analyzed a 100-year climatic record

nution of surface air temperature over snow cover

at Quebec, and showed the spring increase of

reviewed in Munn (1966). Large local tempera-

morning minimum air temperature to stagnate at

0C for several days, until the snow cover dimin-

ture variations have been observed in Alaska by

Benson and Bowling (1973) and in Hokkaido by

ished. The addition of the influence of snow-

2