Surface mass-balance observations and automatic weather station data along a transect near Kangerlussuaq, West Greenland

Abstract

Surface mass-balance data from the Kangerlussuaq transect (K-transect) located on the western part of the Greenland ice sheet near 67° N are presented. The series covers the period 1990-2003 and is the longest series of surface mass-balance measurements in Greenland. The surface mass-balance measurements cover an altitude range of 390-1850 m and show a linear increase of the specific mass balance, with a mass-balance gradient of 3.7 × 10–3 m m–1 and a mean equilibrium-line altitude of 1535 ma.s.l. Interannual variability shows a weak 4 yearly periodicity. In addition to the surface mass-balance data, automatic weather station data at an elevation of approximately 1010m are available for the period 1997-2002. These data are used to explain observed surface mass-balance anomalies over the same 5 years. It is shown that variations in shortwave radiation dominate interannual variability. The mean annual cycle of temperature is characterized by a maximum in summer around the melting point, leading to a mean summer outgoing longwave radiation of approximately 314 W–2. The mean annual cycle in wind speed shows a maximum in winter (on average around 8 m s–1) and a minimum in summer (on average around around 5 m s–1), which is characteristic for a katabatic forcing. During summer the net radiation is on average about 61 Wm–2, which is used for ice melting at a rate of typically 2 cm w.e.d-1. Net radiation contributes 84% of the total energy used for summer melting averaged over the 5 years.

Higher surface mass balance of the Greenland ice sheet revealed by high‐resolution climate modeling

“…The ablation zone is up to 150 km wide in the dry southwest and northeast, and narrower than a single model gridpoint ($11 km) in the wet southeast and extreme northwest. The few available SMB observations from the ablation zone range from À1350 kg m À2 yr À1 on Storstrøm-men in the northeast [Bøggild et al, 1994] to <À3500 kg m À2 yr À1 along the K-transect in the southwest [van de Wal et al, 2005[van de Wal et al, , 2008. These are in good agreement with the map, although the width of the ablation zone in the southwest is overestimated by $20 km and the SMB gradient is underestimated in the lower ablation zone ( Figure S2d).…”

“…[14] Figure 1c shows annual average SMB (1958 -2007), including 500 independent in-situ SMB observations from a variety of published and unpublished sources [Reeh, 1991[Reeh, , 2008Bales et al, 2009;Cogley, 2004;van de Wal et al, 2005]. Although some observations date back to before 1958 and/or represent only a single year of accumulation, qualitative agreement is good.…”

Dust from the dark region in the western ablation zone of the Greenland ice sheet

“…However, large amounts of these angular-faceted, sharp-edged grains are found in both the dark region and the reference ice where precipitation rates are low and snow is eroded by wind (Van den Broeke et al, 2008). This excludes a single recent volcanic source.…”

“…We sampled at various locations along the K-transect, a series of surface mass balance and weather station sites in western Greenland (Van de Wal et al, 2005). The sites are situated on a line perpendicular to the ice sheet margin around 67 • N, and cover both the dark region (S6, S7 and S8), and the bright ice closer to the margin (S4, SHR and S5), see Fig.…”

Sensitivity of Greenland Ice Sheet surface mass balance to surface albedo parameterization: a study with a regional climate model

“…Since 1990, the Institute for Marine and Atmospheric research Utrecht (IMAU) of Utrecht University has performed mass balance and meteorological measurements along a transect (Kangerlussuaq transect or K-transect), located on the western margin of the GrIS at 67 • N ( Van de Wal et al, 2005). The ablation area here is up to 150 km wide with gentle slopes, representing the largest ablation region of the GrIS.…”