Quantifying the Mass Balance of Ice Caps on Severnaya Zemlya, Russian High Arctic. I: Climate and Mass Balance of the Vavilov Ice Cap

Abstract

Due to their remote location within the Russian High Arctic, little is known about the mass balance of ice caps on Severnaya Zemlya now and in the past. Such information is critical, however, to building a global picture of the cryospheric response to climate change. This paper provides a numerical analysis of the climate and mass balance of the Vavilov Ice Cap on October Revolution Island. Mass balance model results are compared with available glaciological and climatological data. A reference climate was constructed at the location of Vavilov Station, representing average conditions for the periods 1974-1981 and 1985-1988. The site of the station has a mean annual temperature of À16.58C, and an annual precipitation of 423 mm water equivalent. The mass balance model was calibrated to the measured mass balance, and tested against the time-dependent evolution of the englacial temperatures (to a depth of 15 m). The mass balance model was then converted to a distributed model for the entire Vavilov Ice Cap. Model results predict the spatial distribution of mass balance components over the ice cap. Processes involving refreezing of water are found to be critical to the ice cap's state of health. Superimposed ice makes up 40% of the total net accumulation, with the remaining 60% coming from firn that has been heavily densified by refreezing.

Reconstructing glacier-based climates of LGM Europe and Russia – Part 1: Numerical modelling and validation methods

“…The climate conditions required to maintain individual glacier mass balance have been modelled in a variety of ways (e.g. Oerlemans, 1991;Hock, 1999;Braithwaite and Zhang, 2000;Bassford et al, 2006). In order to compare the results of large-scale climate models with those derived from glaciers, a method is needed which can extract regional information concerning precipitation and temperature from mass balance models.…”

“…The average melt factors for Scandinavian and Alpine glaciers from Braithwaite and Zhang (2000) are 4.3 mm d −1• C −1 and 6.5 mm d −1• C −1 for snow and ice, respectively; these values were used in this study and the melting threshold was set at 0 • C. For mid to high latitude glaciers the precipitation threshold is usually between 0 • C and 2 • C (e.g. Bassford et al, 2006); a value of 1 • C was used to incorporate the occurrence of snowfall above 0 • C. Rainfall and meltwater were assumed to runoff the glacier surface in the model and make no contribution to net accumulation via refreezing or superimposed ice formation.…”

“…These variables are presented in the dataset on a monthly resolution; they were downscaled to the diurnal climate required by the DDM as follows: it was assumed that precipitation rates were constant throughout each month and hourly precipitation (P h ) was calculated from the CRU2.0 monthly precipitation total as (P CRU ) and days in the month (dpm): The hourly temperature (T h ) was calculated from the mean monthly temperature (T mo ) and diurnal temperature range (T r ) using a cosine function similar to that used by Bassford et al (2006):…”

Early Holocene environments on October Revolution Island, Severnaya Zemlya,Arctic Russia

“…Mean monthly temperatures for July and August are near 0°C, but there is substantial daily variability. Daily temperatures well above freezing occur with warm air masses sourced from northern Siberia (Bassford et al, 2006). Colder temperatures are common with the persistence of cloudy, foggy and windy conditions and summer snowfall is not unusual.…”

“…Colder conditions prevail with katabatic winds occasionally blow from the ice caps. In some years, particularly in September there are one or more marked warming events lasting several days with associated surface melting of the ice caps (Bassford et al, 2006). The annual precipitation ranges from 240 to 400 mm, with most of the precipitation falling as snow.…”