The Distribution of 10 Meter snow Temperatures on the Greenland Ice Sheet

Abstract

All available 10 m. snow temperatures from the Greenland Ice Sheet have been analyzed using multiple regression techniques to develop equations capable of accurately predicting these temperatures. The analysis was carried out for all Greenland and for various sub-areas. The resulting equations show that 10 m. snow temperatures can be accurately predicted from the parameters latitude and elevation. Longitude was found to be a further significant parameter in south Greenland.Gradients of 10 m. snow temperatures versus elevation for north Greenland are close to the dry adiabatic lapse rate indicating adiabatic warming of katabatic winds as the controlling mechanism in their altitudinal distribution. In both south Greenland and the Thule peninsula, gradients of 10 m. snow temperatures versus elevation are markedly greater than the dry adiabatic lapse rate and are highly dependent upon elevation, indicating downward transfer of latent heat in the snow, largely as a result of percolating melt water.An isotherm map, showing the distribution of 10 m. snow temperatures on the Greenland Ice Sheet calculated from the prediction equations, was prepared. The map is based upon a revised contour map of the ice sheet made from a compilation of all known elevations.

Thermal tracing of retained meltwater in the lower accumulation area of the Southwestern Greenland ice sheet

“…Machguth and others (2016) show that percolation down to 10 m depth occurs, under some conditions, at elevations up to at least 2142 m a.s.l., which is at least 110 km inland from the ELA of the Kangerlussuaq region and 195 km inland from the ice margin. While conventionally assumed to be characteristic of average annual air temperatures (Mock and Weeks, 1966; Benson, 1962), 10 m firn temperature now appears to deviate significantly from average annual air temperature over a substantial portion of this ice sheet.…”

“…Mock and Weeks (1966) presented the distribution of 10 m firn temperatures across Greenland based on 112 in situ observations from prior to 1965. The in situ observation closest to our study site that they employ was approximately 60 km south/southwest of KAN_U.…”

Observations of pronounced Greenland ice sheet firn warming and implications for runoff production

“…To derive a set of intercomparable, mean annual site temperatures, which he labels the “10 m temperature” from these observations, Benson calculated the expected seasonal variation on the date of observation, at temperatures observed [see Benson , , pp. 44–53 and Appendix B; Mock and Weeks , ]. This created a standardized mean annual firn temperature for a site that is nearly independent of depth observed or seasonal variation, commonly referred to as the 10 m temperature, although in fact, it is representative of the mean annual firn temperature regardless of depth.…”

Tunnel Valleys, Glacial Surges, and Subglacial Hydrology of the Superior Lobe, Minnesota

“…Surface temperatures of the glacier itself depend largely on elevation. Observations in Greenland show that the surface air-temperature lapse rate with elevation in much of the accumulation zone approximates the dryadiabatic rate of -1° C per 100 m elevation, because the air is dominated by katabatic winds flowing by gravity downslope off the glacier (Mock and Weeks, 1965). In the lower parts of the accumulation zone the gradient is steeper, because percolating meltwater freezes and stores the heat.…”

“…The equilibrium line reflects a complex of meteorological and thermal conditions. In northwestern Greenland on the Thule Peninsula (an area of relatively heavy snowfall), it has an elevation of about 600 m above sea level (Benson, 1962), and the mean annual air temperature is about -12° C (Mock and Weeks, 1965). The equilibrium line rises southward, and in west-central Greenland it has an elevation of 1,500 m, with a near-surface snow temperature of about -15° C (Fig.…”