Abstract
Abstract. Greenland runoff, from ice mass loss and increasing rainfall, is increasing. That runoff, as discharge, impacts the physical, chemical, and biological properties of the adjacent fjords. However, where and when the discharge occurs is not readily available in an open database. Here we provide data sets of high-resolution Greenland hydrologic outlets, basins, and streams, as well as a daily 1958 through 2019 time series of Greenland liquid water discharge for each outlet. The data include 24 507 ice marginal outlets and upstream basins and 29 635 land coast outlets and upstream basins, derived from the 100 m ArcticDEM and 150 m BedMachine. At each outlet there are daily discharge data for 22 645 d – ice sheet runoff routed subglacially to ice margin outlets and land runoff routed to coast outlets – from two regional climate models (RCMs; MAR and RACMO). Our sensitivity study of how outlet location changes for every inland cell based on subglacial routing assumptions shows that most inland cells where runoff occurs are not highly sensitive to those routing assumptions, and outflow location does not move far. We compare RCM results with 10 gauges from streams with discharge rates spanning 4 orders of magnitude. Results show that for daily discharge at the individual basin scale the 5 % to 95 % prediction interval between modeled discharge and observations generally falls within plus or minus a factor of 5 (half an order of magnitude, or +500 %/-80 %). Results from this study are available at https://doi.org/10.22008/promice/freshwater (Mankoff, 2020a) and code is available at http://github.com/mankoff/freshwater (last access: 6 November 2020) (Mankoff, 2020b).
Highlights
Over the past decades, liquid runoff from Greenland has increased (Mernild and Liston, 2012; Bamber et al, 2018; Trusel et al, 2018; Perner et al, 2019), contributing to mass decrease (Sasgen et al, 2020)
– Basins refer to the 100 m × 100 m gridded basins derived from a combination of the ArcticDEM product and the mask
– Modèle Atmosphérique Régional (MAR) and RACMO refer to the regional climate models (RCMs), but when comparing discharge estimates between them or to observations, we use MAR and RACMO to refer to our discharge product derived from the MAR and RACMO RCM runoff variables rather than repeatedly explicitly stating “discharged derived from [MAR|RACMO] runoff”
Summary
Liquid runoff from Greenland has increased (Mernild and Liston, 2012; Bamber et al, 2018; Trusel et al, 2018; Perner et al, 2019), contributing to mass decrease (Sasgen et al, 2020). To date no product provides discharge estimates at high spatial resolution (∼ 100 m; resolving individual streams), daily temporal resolution, for all of Greenland, covering a broad time span (1958 through 2019), from multiple regional climate models (RCMs), and with a simple database access software to support downstream users Complementing that paper, this paper targets Greenland’s point-source liquid water discharge budget by partitioning RCM runoff estimates to all ice margin and coastal outlets The sum of these data and Mankoff et al (2020) is an estimate of the majority of freshwater (in both liquid and solid form) volume flow rates into Greenland fjords. Those two terms comprise the bulk but not all freshwater – they exclude precipitation directly onto the fjord or ocean surface, as well as relatively minor contributions from evaporation and condensation, sea ice formation and melt, or subglacial basal melting
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