Ice mass loss in Greenland, the Gulf of Alaska, and the Canadian Archipelago: Seasonal cycles and decadal trends

Harig, C.; Simons, Frederik J.

doi:10.1002/2016gl067759

Cited by 59 publications

(55 citation statements)

References 53 publications

(63 reference statements)

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“…In our analysis of GRACE data we closely follow the methods of Harig and Simons (), Harig and Simons (), and Harig and Simons (). The Level‐2 CSR GRACE data products are released as Stokes coefficients to spherical harmonic functions, usually up to a bandwidth of degree and order

L = 60

.…”

Section: Monthly Coordinate Time Seriesmentioning

confidence: 99%

Vertical Displacements of the Amazon Basin From GRACE and GPS

2020

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The extent to which Gravity Recovery and Climate Experiment (GRACE)‐recovered gravity anomalies can improve our understanding of Global Positioning System (GPS)‐measured vertical displacements is currently uncertain. To address this issue, we compared vertical displacements measured by 23 GPS stations in the Amazon basin with displacements estimated from GRACE geopotential fields. We show that despite poor correlation ( r2=0.15) between rate estimates in GPS and GRACE‐derived displacement time series, further analyses reveal low bias between annual amplitude estimates and a scaling near 1. There is higher correlation ( r2=0.78) between annual periodic motions, with near 1 to 1 agreement, but there is poor correlation ( r2=0.02) and little agreement between semiannual amplitude estimates. Subtracting GRACE displacements from the GPS time series flattens the GPS power spectra, reducing the spectral index magnitude, on average, from −1.2759±0.0007 (“fractional Brownian motion”) to −0.3346±0.0006 (“fractional Gaussian noise”), suggesting that some fraction of the apparent GPS error correlation derives from mass loading signals that are not completely characterized by secular trends or seasonal periodic motions. From March 2011 to November 2016, we find a GPS and GRACE‐derived displacement combined average uplift of the Amazon basin of 1.20±0.26 mm/yr and combined average annual periodic motion of 10.22±0.57 mm. Deviations from a standard trajectory model for site motion are apparent in both data sets and appear to coincide with various flooding and drought events between 2011 and 2016, which suggests that the GPS coordinate time series record displacements driven by large‐scale climate oscillations.

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L = 60

.…”

Section: Monthly Coordinate Time Seriesmentioning

confidence: 99%

Vertical Displacements of the Amazon Basin From GRACE and GPS

2020

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“…GrIS has experienced an increase in surface melt production and runoff by approximately 30%, with the melt season extended by an average of 10 days (Box, Bromwich, & Bai, ; Box & Ski, ; Mernild, Mote, & Liston, ; Mcleod & Mote, ; Mote, ; Tedesco et al, ; Zwally et al, ). Commensurately, the acceleration of mass discharge, thinning, and terminus retreat has been documented for many of GrIS major marine‐terminating outlet glaciers (Aschwanden, Fahnestock, & Truffer, ; Harig & Simons, ; Jin & Zou, ; Moon et al, ; Mouginot et al, ).…”

Section: Introductionmentioning

confidence: 97%

Seasonal Variability in Regional Ice Flow Due to Meltwater Injection Into the Shear Margins of Jakobshavn Isbræ

2017

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The impact of meltwater injection into the shear margins of Jakobshavn Isbræ via drainage from water‐filled crevasses on ice flow is examined. We use Landsat‐8 Operational Land Imager panchromatic, high‐resolution imagery to monitor the spatiotemporal variability of seven water‐filled crevasse ponds during the summers of 2013 to 2015. The timing of drainage from water‐filled crevasses coincides with an increase of 2 to 20% in measured ice velocity beyond Jakobshavn Isbræ shear margins, which we define as extramarginal ice velocity. Some water‐filled crevasse groups demonstrate multiple drainage events within a single melt season. Numerical simulations show that hydrologic shear weakening due to water‐filled crevasse drainage can accelerate extramarginal flow by as much as ~35% within 10 km of the margins and enhance mass flux through the shear margins by 12%. This work demonstrates a novel mechanism through which surface melt can influence regional ice flow.

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“…Unprecedented changes over the last 40 years consign the Arctic to a climate trajectory unobserved in more than two million years with an ice-free summertime Arctic expected by mid-century [28][29][30][31]. Other ongoing changes, such as mountain glacier mass loss, Greenland Ice Sheet melt, vegetation type, ecosystem structure, and permafrost thaw [32][33][34][35][36][37] also illustrate a shifting Arctic climate. Though all changes are significant, Arctic sea ice decline has directly contributed to changes in surface turbulent fluxes [38,39].…”

Section: Introductionmentioning

confidence: 99%

On the Increasing Importance of Air-Sea Exchanges in a Thawing Arctic: A Review

et al. 2018

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Forty years ago, climate scientists predicted the Arctic to be one of Earth's most sensitive climate regions and thus extremely vulnerable to increased CO 2 . The rapid and unprecedented changes observed in the Arctic confirm this prediction. Especially significant, observed sea ice loss is altering the exchange of mass, energy, and momentum between the Arctic Ocean and atmosphere.As an important component of air-sea exchange, surface turbulent fluxes are controlled by vertical gradients of temperature and humidity between the surface and atmosphere, wind speed, and surface roughness, indicating that they respond to other forcing mechanisms such as atmospheric advection, ocean mixing, and radiative flux changes. The exchange of energy between the atmosphere and surface via surface turbulent fluxes in turn feeds back on the Arctic surface energy budget, sea ice, clouds, boundary layer temperature and humidity, and atmospheric and oceanic circulations. Understanding and attributing variability and trends in surface turbulent fluxes is important because they influence the magnitude of Arctic climate change, sea ice cover variability, and the atmospheric circulation response to increased CO 2 . This paper reviews current knowledge of Arctic Ocean surface turbulent fluxes and their effects on climate. We conclude that Arctic Ocean surface turbulent fluxes are having an increasingly consequential influence on Arctic climate variability in response to strong regional trends in the air-surface temperature contrast related to the changing character of the Arctic sea ice cover. Arctic Ocean surface turbulent energy exchanges are not smooth and steady but rather irregular and episodic, and consideration of the episodic nature of surface turbulent fluxes is essential for improving Arctic climate projections.

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Ice mass loss in Greenland, the Gulf of Alaska, and the Canadian Archipelago: Seasonal cycles and decadal trends

Cited by 59 publications

References 53 publications

Vertical Displacements of the Amazon Basin From GRACE and GPS

Vertical Displacements of the Amazon Basin From GRACE and GPS

Seasonal Variability in Regional Ice Flow Due to Meltwater Injection Into the Shear Margins of Jakobshavn Isbræ

On the Increasing Importance of Air-Sea Exchanges in a Thawing Arctic: A Review

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