gios Publications

2024:

Autonomously self-powered measurements of methane emissions in the High Arctic, showing novel installations operating as part of the Greenland Integrated Observing System in early winter, Zackenberg, northeast Greenland. Photo: Mikhail Mastepanov

Christensen, T.R. Wetland emissions on the rise. Nat. Clim. Chang. (2024). https://doi.org/10.1038/s41558-024-01938-y.

Abstract:

Methane concentrations are rising faster than ever in the atmosphere. Now, a compilation of observations points towards increased methane emissions from Arctic wetlands as being partly responsible.

The rate of increase in atmospheric methane concentration has been accelerating since 2016, as shown by recent analyses of atmospheric records1. This calls for renewed attention to this strong greenhouse gas as a very important player in the global climate. The increase in atmospheric methane may be further considered a diagnosis of ‘illness’ in the Earth system, indicating a positive (amplifying) feedback to climate change. The sources of methane causing this acceleration are not yet clear. However, it is well known that substantial global wetland emissions of methane can contribute to it, and the tropical region is being pointed out as a potential source of this methane1,2. Writing in Nature Climate Change, Yuan et al.3 document a significant overarching increasing trend also in northern wetland emissions.

2023:

Figure 1(a) Study site location in Greenland. (b) Close-up of the study site with location of the gauging station and the PROMICE (Programme for Monitoring of the Greenland Ice Sheet) weather station. (c) UAV mission area I and II with location of GCPs overlaid on a four-band Planet Team (2017) acquisition from 23 August 2021. The yellow triangles illustrate the only two reliable fix solution GCPs. Due to image gaps at the western part of the lake, the produced UAV DEM is filled with elevation data from two ArcticDEMs acquired on 19 September 2014 and 2 August 2015.

Dømgaard, M., Kjeldsen, K. K., Huiban, F., Carrivick, J. L., Khan, S. A., and Bjørk, A. A. (2023): Recent changes in drainage route and outburst magnitude of the Russell Glacier ice-dammed lake, West Greenland, The Cryosphere, 17, 1373–1387, https://doi.org/10.5194/tc-17-1373-2023, 2023.

Abstract: Glacial lake outburst floods (GLOFs) or jökulhlaups from ice-dammed lakes are frequent in Greenland and can influence local ice dynamics and bedrock motion, cause geomorphological changes, and pose flooding hazards. Multidecadal time series of lake drainage dates, volumes, and flood outlets are extremely rare. However, they are essential for determining the scale and frequency of future GLOFs, for identifying drainage mechanisms, and for mitigating downstream flood effects. In this study, we use high-resolution digital elevation models (DEMs) and orthophotos (0.1 × 0.1 m) generated from uncrewed-aerial-vehicle (UAV) field surveys, in combination with optical satellite imagery. This allows us to reconstruct robust lake volume changes associated with 14 GLOFs between 2007 and 2021 at Russell Glacier, West Greenland. As a result, this is one of the most comprehensive and longest records of ice-dammed lake drainages in Greenland to date. Importantly, we find a mean difference of  10 % between our lake drainage volumes when compared with estimates derived from a gauged hydrograph 27 km downstream. Due to thinning of the local ice dam, the potential maximum drainage volume in 2021 is  60 % smaller than that estimated to have drained in 2007. Our time series also reveals variations in the drainage dates ranging from late May to mid-September and drainage volumes ranging between 0.9 and 37.7 Mm3. We attribute these fluctuations between short periods of relatively high and low drainage volumes to a weakening of the ice dam and an incomplete sealing of the englacial tunnel following the large GLOFs. This syphoning drainage mechanism is triggered by a reduction in englacial meltwater, likely driven by late-season drainage and sudden air temperature reductions, as well as annual variations in the glacial drainage system. Furthermore, we provide geomorphological evidence of an additional drainage route first observed following the 2021 GLOF, with a subglacial or englacial flow pathway, as well as supraglacial water flow across the ice margin. It seems probable that the new drainage route will become dominant in the future. This will drive changes in the downstream geomorphology and raise the risk of flooding-related hazards as the existing buffering outlet lakes will be bypassed.

(a) Stars indicate the positions of the QAS and KAN PROMICE automatic weather stations (AWSs) with precipitation gauges and the location of the Narsaq meteorological station. The lowest QAS location on land is not a full AWS, but a TR-525 L gauge with air temperature like that at all sites, except Narsaq. (b) Example illustration of rain gauge placement on the QAS_U PROMICE AWS on 29 August, 2020.

Box JE., Nielsen KP., Yang X., Niwano M., Wehrlé A., van As D., Fettweis X., Køltzow MAØ., Palmason B., Fausto RS., van den Broeke MR., Huai B., Ahlstrøm AP., Langley K., Dachauer A., Noël B. (2023). Greenland ice sheet rainfall climatology, extremes and atmospheric river rapids. Meteorol. Appl. 30:2134. https://doi.org/10.1002/met.2134

Abstract: Greenland rainfall has come into focus as a climate change indicator and from a variety of emerging cryospheric impacts. This study first evaluates rainfall in five state-of-the-art numerical prediction systems (NPSs) (CARRA, ERA5, NHM-SMAP, RACMO, MAR) using in situ rainfall data from two regions spanning from land onto the ice sheet. The new EU Copernicus Climate Change Service (C3S) Arctic Regional ReAnalysis (CARRA), with a relatively fine (2.5 km) horizontal grid spacing and extensive within-model-domain observational initialization, has the lowest average bias and highest explained variance relative to the field data. ERA5 inland wet bias versus CARRA is consistent with the field data and other research and is presumably due to more ERA5 topographic smoothing. A CARRA climatology 1991–2021 has rainfall increasing by more than one-third for the ice sheet and its peripheral ice masses. CARRA and in situ data illuminate extreme (above 300 mm per day) local rainfall episodes. A detailed examination CARRA data reveals the interplay of mass conservation that splits flow around southern Greenland and condensational buoyancy generation that maintains along-flow updraft ‘rapids’ 2 km above sea level, which produce rain bands within an atmospheric river interacting with Greenland. CARRA resolves gravity wave oscillations that initiate as a result of buoyancy offshore, which then amplify from terrain-forced uplift. In a detailed case study, CARRA resolves orographic intensification of rainfall by up to a factor of four, which is consistent with the field data.

2022:

Fig.: Marine container unit in the outer part of Young Sound (left) and terrestrial container unit inside the fjord near the Zackenberg Research Station (right) in NE Greenland (74N). The marine unit collects data from the meteorological mast in the background and from the fjord ca 1 km off the coast. The terrestrial container collects data from the meteorological mast in the foreground and from various installations in the landscape.

Rysgaard S, Bjerge K, Boone W, Frandsen E, Graversen M, Høye TTi, Jensen B, Johnen G, Jackowicz-Korczynski MA, Kerby JT, Kortegaard S, Mastepanov M, Melvad C, Mikkelsen PS, Mortensen K, Nørgaard C, Poulsen E, Riis T, Sørensen LL, Christensen TR (2022). A mobile observatory powered by sun and wind for near real time measurements of atmospheric, glacial, terrestrial, limnic and coastal oceanic conditions in remote off-grid areas. 2468-0672 / 2022 Published by Elsevier Ltd. https://doi.org/10.1016/j.ohx.2022.e00331

Abstract: Climate change is rapidly altering the Arctic environment. Although long-term environmental observations have been made at a few locations in the Arctic, the incomplete coverage from ground stations is a main limitation to observations in these remote areas. Here we present a wind and sun powered multi-purpose mobile observatory (ARC-MO) that enables near real time measurements of air, ice, land, rivers, and marine parameters in remote off-grid areas. Two test units were constructed and placed in Northeast Greenland where they have collected data from cabled and wireless instruments deployed in the environment since late summer 2021. The two units can communicate locally via WiFi (units placed 25 km apart) and transmit near-real time data globally over satellite. Data are streamed live and accessible from (https://gios.org). The cost of one mobile observatory unit is c. 304.000€. These test units demonstrate the possibility for integrative and automated environmental data collection in remote coastal areas and could serve as models for a proposed global observatory system.

Fig.: Automatic weather station (AWS) locations and the Watson River catchment appear on both panels. (a) An area of the western Greenland ice sheet on 20 August 2021 featured using a 1 km Sentinel-3 Ocean Land Color Instrument RGB image with inset 10 m Sentinel-2B true color images illustrating saturated snow and dark bare ice after the atmospheric river. (b) Greenland Climate Network and Program for the Monitoring of the Greenland ice sheet AWS locations and the expansion of wet snow area over 12-hr recorded by AMSR satellite passive microwave between August 13, 16 UTC and August 14, 04 UTC.

Box JE, Wehrlé A, van As, D, Fausto RS, Kjeldsen KK, Dachauer A, Ahlstrøm AP, and Picard G (2022). Greenland ice sheet rainfall, heat and albedo feedback impacts from the mid-August 2021 atmospheric River. Geophysical Research Letters, 49. https://doi.org/10.1029/2021GL097356

Abstract: Rainfall at the Greenland ice sheet Summit 14 August 2021, was delivered by an atmospheric river (AR). Extreme surface ablation expanded the all-Greenland bare ice area to near-record-high with snowline climbing up to 788 ± 90 m. Ice sheet wet snow extent reached 46%, a record high for the 15–31 August AMSR data since 2003. Heat-driven firn deflation averaged 0.14 ± 0.05 m at four accumulation area automatic weather stations (AWSs). Energy budget calculations from AWS data indicate that surface heating from rainfall is much smaller than from either the sensible, latent, net-longwave or solar energy fluxes. Sensitivity tests show that without the heat-driven snow-darkening, melt at 1,840 m would have totaled 28% less. Similarly, at 1,270 m elevation, without the bare ice exposure, melting would have been 51% less. Proglacial river discharge was the highest on record since 2006 for late August and confirms the melt-sustaining effect of the albedo feedback.

Video: Greenland Ice Sheet Atmospheric River – Rainfall, Heat and Albedo Feedback Impacts