Climatological Observations and Predicted Sublimation Rates at Lake Hoare, Antarctica

Abstract

In December 1985, an automated meteorological station was established at Lake Hoare in the dry valley region of Antarctica. Here, we report on the first year-round observations available for any site in Taylor Valley. This dataset augments the year-round data obtained at Lake Vanda (Wright Valley) by winter-over crews during the late 1960s and early 1970s. The mean annual solar flux at Lake Hoare was 92 W m-2 during 1986, the mean air temperature -17.3 degrees C, and the mean 3-m wind speed 3.3 m s-1. The local climate is controlled by the wind regime during the 4-month sunless winter and by seasonal and diurnal variations in the incident solar flux during the remainder of the year. Temperature increases of 20 degrees-30 degrees C are frequently observed during the winter due to strong föhn winds descending from the Polar Plateau. A model incorporating nonsteady molecular diffusion into Kolmogorov-scale eddies in the interfacial layer and similarity-theory flux-profiles in the surface sublayer, is used to determine the rate of ice sublimation from the acquired meteorological data. Despite the frequent occurrence of strong winter föhns, the bulk of the annual ablation occurs during the summer due to elevated temperatures and persistent moderate winds. The annual ablation from Lake Hoare is estimated to have been 35.0 +/- 6.3 cm for 1986.

Sediment Melt-Migration Dynamics in Perennial Antarctic Lake Ice

“…At the same time, air temperatures must allow for a balance between the accretion of new (bottom) ice and the ablation of old (surface) ice. The ablation rate of the Lake Fryxell ice cover varies considerably because of summertime melt and the dry katabatic winds which are most frequent during non-summer months (Henderson et al, 1966;Doran et al, 2002b (Clow et al, 1988). Much higher ablation rates, up to ,1.5 m yr…”

“…Downwelling PAR was measured on the ice surface, next to the sediment, with a Licor 190-SA quantum detector and LI-1000 datalogger. These values were converted to shortwave irradiance using a conversion factor of 0.5 W m 22 per mmol photon m 22 s 21 (Clow et al, 1988). Albedos of beach sand and ice table ( Fig.…”

“…Based on MCM LTER records for [2001][2002][2003][2004], the surface ablation rates at Lake Fryxell during the months of December and January were an order of magnitude greater than during other months. Intraseasonal variation in surface ablation was also noted at Lake Hoare by Clow et al (1988) and is likely associated with summertime melting at the ice surface. The ice cover thickness of Lake Fryxell ranged from 3.8 to 4.5 m between 1961 and 1963 (Henderson et al, 1966), and from 3.5 to 6.0 m between 1995 and 2006 (Priscu, unpublished data; MCM LTER).…”

Daily cycle of the surface energy balance in Antarctica and the influence of clouds

“…Similar results have been reported on the basis of data from automatic weather stations (AWS, Kikuchi et al, 1988;Allison, 1985;Clow et al, 1988;Stearns and Weidner, 1993;Reijmer and Oerlemans, 2002;Renfrew and Anderson, 2002), as well as theoretical and numerical modelling studies (Gallée and Schayes, 1992;Parish et al, 1993;Sorbjan et al, 1986;.…”

Sensible heat exchange at the Antarctic snow surface: a study with automatic weather stations

“…When AWSs are equipped with sonic height rangers, precipitation events can be monitored (Reijmer and van den Broeke, 2003) to support the interpretation of climate records in firn/ice cores (Helsen et al, in press). If humidity measurements are available, then similarity theory may be used to calculate sublimation from AWS data (Clow et al, 1988;Stearns and Weidner, 1993; in press a). Reliable radiation sensors deployed on AWSs have improved our knowledge of the surface radiation balance in Antarctica (van den Broeke et al, 2004a,b).…”