R. S. W. van de Wal

Abstract: [1] This paper presents atmospheric concentrations of ethane, propane, acetylene, and methyl chloride, inferred from firn air by using a numerical one-dimensional firn diffusion model. The firn air was collected on the Antarctic plateau in Dronning Maud Land during the Norwegian Antarctic Research Expedition (NARE) 2000/2001. The influences of seasonal variations in temperature and pressure and the variation in accumulation rate were studied and are not negligible, but appear to cancel each other out if all variability is taken into account. This paper also demonstrates that firn air from the uppermost firn layer (30 m) can be used to derive seasonal cycles of these trace gases, without needing a year-round facility. These cycles display higher atmospheric mixing ratios during the Antarctic winter and lower atmospheric mixing ratios in summer. The cycles for the year 2000 show amplitudes of 140 +/- 25 ppt for ethane, 30 +/- 10 ppt for propane, 24 +/- 6 ppt for acetylene, and 40 +/- 20 ppt for methyl chloride. For ethane and propane the amplitudes and months of maximum atmospheric concentration (phase) are in reasonable agreement with year-round measurements at the South Pole and Baring Head (New Zealand). The amplitudes for methyl chloride and acetylene are significantly greater than seen in year-round measurements at the South Pole and at Neumayer (Antarctica), although the phase is in line. While biomass burning and removal by OH radicals can partially explain these large amplitudes, the exact cause still remains unclear for methyl chloride and acetylene.

TL;DR: In this article, the authors compare the performance of existing numerical ice sheet models in simulating modern control and mid-Pliocene ice sheets by a suite of sensitivity experiments guided by available proxy records.

TL;DR: In this paper, the authors presented a comprehensive set of 100-year specific mass balance series for 30 Swiss glaciers and compared the fluctuations in alpine glacier specific mass balances to climatic changes attributed to the Atlantic Multidecadal Oscillation (AMO), concluding that AMO related climate variations are far less important to the recent mass loss than the trend caused by gradual warming over the past century.

TL;DR: In this article, the authors presented an attempt to reconcile methane carbon isotope records from 11 firn sites from both Greenland and Antarctica to reconstruct a consistent 13C(CH4) history over the last 50 yr.

TL;DR: Airborne P-band SAR data have been acquired in Greenland, and both offset tracking and DInSAR have been applied to the full resolution data as well as to data degraded to the resolution of Biomass, and first results are presented.