Greenland liquid water discharge from 1958 through 2019

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).

Greenland ice sheet mass balance from 1840 through next week

“…However, exactly where, when, and how that mass has been lost is not precisely known. There are three common methods for estimating mass balance -changes in gravity (Barletta et al, 2013;Groh et al, 2019;The IMBIE Team, 2019;Velicogna et al, 2020), changes in volume (Simonsen et al, 2021a;Sørensen et al, 2011;Zwally and Giovinetto, 2011;Sasgen et al, 2012;Smith et al, 2020), or the input/output (IO) method (Colgan et al, 2019;Rignot et al, 2019). Each provides some estimate of where, when, and how the mass is lost or gained, and each method has some limitations.…”

“…In this work we introduce the new PROMICE Greenland ice sheet mass balance dataset based on the IO method, updating the previous product from Colgan et al (2019). IO inputs are the positive SMB fields from one RCM (1840RCM ( through 1985 to three RCMs (1986 onward), IO outputs are the negative SMB fields from the same RCM(s), the basal mass balance, and an estimate of dynamic ice discharge.…”

Flood events caused by discharge from Qaanaaq Glacier, northwestern Greenland

“…It should be noted that our measurements were utilized for validation of daily discharge from all Greenlandic drainage basins estimated from output of two regional climate models (Mankoff and others, 2020). The comparison of the data from 2017 to 2019 indicated that one of the models (MAR) (e.g.…”

Hourly surface meltwater routing for a Greenlandic supraglacial catchment across hillslopes and through a dense topological channel network

“…A recent synthesis showed that SMB models vary considerably given the same forcing, and readers are referred to this and other literature for further information on why these models might disagree. Smith et al (2017) and Mankoff et al (2020) have both explored what these differences mean for water exiting the GrIS, but our purpose is to demonstrate the importance of coupling SMB model output with a surface flow routing model to understand runoff transport before it enters the englacial system. This enables rigorous estimation of supraglacial flow accumulation and Figure 7.…”