Sensitivity of a distributed temperature-radiation index melt model based on AWS observations and surface energy balance fluxes, Hurd Peninsula glaciers, Livingston Island, Antarctica

Abstract

Abstract. We use an automatic weather station and surface mass balance dataset spanning four melt seasons collected on Hurd Peninsula Glaciers, South Shetland Islands, to investigate the point surface energy balance, to determine the absolute and relative contribution of the various energy fluxes acting on the glacier surface and to estimate the sensitivity of melt to ambient temperature changes. Long-wave incoming radiation is the main energy source for melt, while short-wave radiation is the most important flux controlling the variation of both seasonal and daily mean surface energy balance. Short-wave and long-wave radiation fluxes do, in general, balance each other, resulting in a high correspondence between daily mean net radiation flux and available melt energy flux. We calibrate a distributed melt model driven by air temperature and an expression for the incoming short-wave radiation. The model is calibrated with the data from one of the melt seasons and validated with the data of the three remaining seasons. The model results deviate at most 140 mm w.e. from the corresponding observations using the glaciological method. The model is very sensitive to changes in ambient temperature: a 0.5 • C increase results in 56 % higher melt rates.

Trends in Antarctic Peninsula surface melting conditions from observations and regional climate modeling

“…Although surface snowmelt is not directly proportional to air temperature due to non‐linear interactions between components of the surface energy balance, the PDD approach is often used due to relatively modest data requirements (appropriate here given the constraints of our input data, T i only) and the recognized and robust empirical relationship between melt and air temperatures [e.g., Ohmura , ; Hock , ]. This relationship has been shown for glaciers on Livingstone Island in the Antarctic Peninsula [ Jonsell et al , ], although [ Kuipers Munneke et al , ] note that calculations from Larsen C ice shelf based only on temperatures measured well above the snow surface may underestimate total melt. Trends in time‐series of ϕ n were calculated within 95% confidence intervals using a minimisation of squared deviations (least‐squares) approach.…”

“…Although surface snowmelt is not directly proportional to air temperature due to non-linear interactions between components of the surface energy balance, the PDD approach is often used due to relatively modest data requirements (appropriate here given the constraints of our input data, T i only) and the recognized and robust empirical relationship between melt and air temperatures [e.g., Ohmura, 2001;Hock, 2005]. This relationship has been shown for glaciers on Livingstone Island in the Antarctic Peninsula [Jonsell et al, 2012] The basis for detection of melt from QSCAT data is the abrupt and significant reduction in microwave backscatter caused by the presence of liquid water in near surface snow and firn layers [Nghiem et al, 2001;Ulaby et al, 1986;Wang et al, 2005Wang et al, , 2007Sharp and Wang, 2009]. The SeaWinds scatterometer on QSCAT made dual polarization measurements of backscatter (normalized radar cross section, s 0 ) between June 1999 and November 2009 using a conically scanning antenna operating at Ku-band (13.4 GHz) frequency.…”

Modeling the Controls on the Front Position of a Tidewater Glacier in Svalbard

“…The water in crevasses is mostly produced by melting at the glacier surface, so the mean water depth in crevasses can be parameterized in terms of surface melting, which can be modeled either using air temperature or temperature-radiation index models (e.g., Jonsell et al, 2012) or energy-balance models (e.g., Hock and Holmgren, 2005) trained by observed and/or modeled data (e.g., Finkelnburg, 2013). This allows us to replace a parameter inherently difficult to measure in the field by another that can be based on easier field observations, models, or both.…”

Geomatic methods applied to the study of the front position changes of Johnsons and Hurd Glaciers, Livingston Island, Antarctica, between 1957 and 2013

“…The annual average temperature at Juan Carlos I Station (12 m a.s.l., in Hurd Peninsula) between 1988 and 2011 was −0.9 • C, with average summer (DJF) and winter (JJA) temperatures of 2.4 and −4.4 • C, respectively (Osmanoglu et al, 2014). The main glaciological studies in Hurd Peninsula include cartography of volcanic ash layers (Palà et al, 1999;Ximenis, 2001;Molina, 2014), shallow ice coring , numerical modeling of glaciers dynamics (Martín et al, 2004;Otero et al, 2010), analysis of glacier volume changes 1957-2000 (Molina et al, 2007), seismic and ground-penetrating radar surveys (Benjumea et al, 1999(Benjumea et al, , 2001(Benjumea et al, , 2003Navarro et al, 2005Navarro et al, , 2009, modeling of melting (Jonsell et al, 2012), massbalance observations Ximenis, 2001;Navarro et al, 2013) and geomorphological and glacier dynamics studies (Ximenis et al, 2000;Molina, 2014). Glaciological studies covering the whole Livingston Island include the analysis of Livingston ice cap front position changes 1956-1996, ground-penetrating radar surveys ) and estimates of ice discharge to the ocean (Osmanoglu et al, 2014).…”