Contrasts between the summertime surface energy balance and boundary layer structure at Dome C and Halley stations, Antarctica

Abstract

[1] The Antarctic research stations of Dome C and Halley lie at similar latitudes ($75°S) and are thus subject to similar diurnal variation of solar radiation at the top of the atmosphere. However, the response of the atmospheric boundary layer to this diurnally varying forcing differs greatly at the two stations. At Dome C during summer there is a strong diurnal cycle in near-surface temperature and wind speed, and a shallow ($350 m) convective boundary layer is observed to grow in response to diurnal heating. At Halley, diurnal variations in temperature and wind speed are smaller than those at Dome C, and there is no clear diurnal variability in boundary layer depth. Analysis of the summertime surface energy budget for both stations indicates that the main reason for the different diurnal variability at the two stations is the greater partitioning of available energy into latent heat flux at the warmer Halley station. We argue that the diurnally varying convective boundary layer observed at Dome C will not be typical of the whole of the East Antarctic plateau.

Atmospheric moisture supersaturation in the near-surface atmosphere at Dome C, Antarctic Plateau

“…The flux is positive during the summer months indicating sublimation of snow, while during winter months the flux is negative, indicating condensation to the surface. Such seasonality is in agreement with that reported by King et al (2001) at Halley station, which is situated in coastal Antarctica but at a latitude similar to that of Dome C. The positive summer values reflect the predominance of snow sublimation during the summer diurnal cycle (Genthon et al, 2013) because, in summer, the surfaceatmosphere exchanges are larger during convective activity in the afternoon than in the night hours when the boundary layer becomes stable (King et al, 2006;Vignon et al, 2016). Integrated over the full year 2015, the net water vapor flux is 0.2763 cm w.e.…”

“…Two different approaches are used. By default, z 0q = z 0 as in King et al (2001), and in a second case, z 0q is calculated with Andreas (1987) theoretical formula, which at Dome C yields z 0q values lower than z 0 by approximately one order of magnitude. Uncertainties on flux calculations are estimated from the variance of results obtained with the different choices of stability functions and roughness length.…”

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

“…In spite of this, results from numerous dedicated off-pole meteorological experiments show a strong diurnal cycle of summertime Antarctic surface-layer climate and SEB (Liljequist, 1957;Ohata et al, 1985;Wendler et al, 1988;Heinemann and Rose, 1990; Van den Broeke and Bintanja, 1995;Bintanja and van den Broeke, 1995;Mastrantonio et al, 1999;Bintanja, 2000;Van As et al, 2005a;Argentini et al, 2005;King et al, 2006). 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;.…”

Wavelike Structures in the Turbulent Layer During the Morning Development of Convection at Dome C, Antarctica

“…"Night" and "day" are quoted because the sun is always above the horizon during the polar summer (from the end of October to the end of February). The presence of a distinct diurnal cycle differentiates the Dome C site from other well-investigated sites in Antarctica, such as the South Pole and Halley, where the daily cycle during the summer is absent (King et al 2006;Neff et al 2008).…”