Extending the QuikSCAT record of seasonal melt–freeze transitions over Arctic sea ice using ASCAT

Mortin, Jonas; Howell, Stephen E. L.; Wang, Libo; Derksen, Chris; Svensson, Gunilla; Graversen, Rune; Schröder, Thomas

doi:10.1016/j.rse.2013.11.004

Cited by 55 publications

(37 citation statements)

References 70 publications

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“…ASCAT backscatter intensity is dependent on surface properties of the snow and ice. Melt onset is characterized by a shift from high to low backscatter due to the presence of liquid water in the snow, which causes absorption of the incident microwaves within the snow pack and masks the backscatter signature of the underlying ice (Mortin et al, ). Once the snow has melted, the disappearance of wet snow, the reduction of liquid water content within hummocks, and the presence of bare ice and wind‐roughened melt ponds cause a transition from low backscatter to high backscatter (Mortin et al, ).…”

Section: Methodsmentioning

confidence: 99%

Airborne Observations of Summer Thinning of Multiyear Sea Ice Originating From the Lincoln Sea

et al. 2019

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To better understand recent changes of Arctic sea ice thickness and extent, it is important to distinguish between the contributions of winter growth and summer melt to the sea ice mass balance. In this study we present a Lagrangian approach to quantify summer sea ice melt in which multiyear ice (MYI) floes that were surveyed by airborne electromagnetic thickness sounding within Nares Strait during summer were backtracked, using satellite imagery, to a region in close proximity (3–20 km) to spring ice thickness surveys carried out in the Lincoln Sea. Typical modal total MYI thicknesses, including ~0.4‐m snow, ranged between 3.9 and 4.7 m in the Lincoln Sea during April. Ice‐only modal thicknesses were between 2.2 and 3.0 m in Nares Strait during August. Total thinning including snow and ice was 1.3 ± 0.1 m including 0.4 ± 0.09 m of snow melt and 0.9 ± 0.2 m of ice melt. This translates to a seasonal net heat input of 305 ± 69 MJ/m2 (262 ± 60 MJ/m2 for ice only) and seasonal net heat flux of 57 ± 13 W/m2 (45 ± 10 W/m2 for ice only), which is unlikely to be explained by solar radiation fluxes alone. Furthermore, our approach provides an improvement on traditional ice mass balance buoy estimates because it integrates melt over larger spatial scales, where melt can be highly variable due to differential melt experienced between melt ponds, bare ice, hummocks, and ridges.

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Section: Methodsmentioning

confidence: 99%

Airborne Observations of Summer Thinning of Multiyear Sea Ice Originating From the Lincoln Sea

et al. 2019

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“…As temperature increases in the spring and summer, and liquid water content of the snow increases, resulting in more forward scattering and decreased backscatter [76]. This temperature-driven backscatter change in snow has been used to map snow and melt onset over the Arctic Ocean [30], [77]- [79], freshwater lakes [80], [81], and over land in northern Canada [30] and globally [82].…”

Section: Melt-onset Mappingmentioning

confidence: 99%

Polar Applications of Spaceborne Scatterometers

Long

2017

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

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Wind scatterometers were originally developed for observation of near-surface winds over the ocean. They retrieve wind indirectly by measuring the normalized radar cross section (σ o ) of the surface, and estimating the wind via a geophysical model function relating σ o to the vector wind. The σ o measurements have proven to be remarkably capable in studies of the polar regions where they can map snow cover; detect the freeze/thaw state of forest, tundra, and ice; map and classify sea ice; and track icebergs. Further, a long time series of scatterometer σ o observations is available to support climate studies. In addition to fundamental scientific research, scatterometer data are operationally used for sea-ice mapping to support navigation. Scatterometers are, thus, invaluable tools for monitoring the polar regions. In this paper, a brief review of some of the polar applications of spaceborne wind scatterometer data is provided. The paper considers both C-band and Ku-band scatterometers, and the relative merits of fan-beam and pencil-beam scatterometers in polar remote sensing are discussed.

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“…The rising temperatures help to start the snowmelt in April (or later, depending on local, regional, and inter-annual variability [6,33]). Within the watershed permafrost degradation period, river flows resume their movements towards the Laptev and East Siberian Seas [34], and the spring re-vegetation favours wetter conditions in May (about 10 kg/m 2 ) by evapotranspiration [35] at the Siberian/Mackenzie watersheds ( Figure 1).…”

Section: Tcwv Featuresmentioning

confidence: 99%

Enhanced MODIS Atmospheric Total Water Vapour Content Trends in Response to Arctic Amplification

et al. 2017

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In order to assess the strength of the water vapour feedback within Arctic climate change, 15 years of the total column-integrated density of water vapour (TCWV) from the moderate resolution imaging spectrometer (MODIS) are analysed. Arctic TCWV distribution, trends, and anomalies for the 2001-2015 period, broken down into seasons and months, are analysed. Enhanced local spring TCWV trends above the terrestrial Arctic regions are discussed in relation to land snow cover and vegetation changes. Upward TCWV trends above the oceanic areas are discussed in lien with sea ice extent and sea surface temperature changes. Increased winter TCWV (up to 40%) south of the Svalbard archipelago are observed; these trends are probably driven by a local warming and sea ice extent decline. Similarly, the Barents/Kara regions underwent wet trends (up to 40%), also associated with winter/fall local sea ice loss. Positive late summer TCWV trends above the western Greenland and Beaufort seas (about 20%) result from enhanced upper ocean warming and thereby a local coastal decline in ice extent. The Mackenzie and Siberia enhanced TCWV trends (about 25%) during spring are found to be associated with coincident decreased snow cover and increased vegetation, as a result of the earlier melt onset. Results show drier summers in the Eurasia and western Alaska regions, thought to be affected by changes in albedo from changing vegetation. Other TCWV anomalies are also presented and discussed in relation to the dramatic decline in sea ice extent and the exceptional rise in sea surface temperature.

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Extending the QuikSCAT record of seasonal melt–freeze transitions over Arctic sea ice using ASCAT

Cited by 55 publications

References 70 publications

Airborne Observations of Summer Thinning of Multiyear Sea Ice Originating From the Lincoln Sea

Airborne Observations of Summer Thinning of Multiyear Sea Ice Originating From the Lincoln Sea

Polar Applications of Spaceborne Scatterometers

Enhanced MODIS Atmospheric Total Water Vapour Content Trends in Response to Arctic Amplification

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