Local advection of sensible heat in the snowmelt landscape of Arctic tundra

Neumann, Natasha; Marsh, Philip

doi:10.1002/(sici)1099-1085(199808/09)12:10/11<1547::aid-hyp680>3.0.co;2-z

Cited by 66 publications

(45 citation statements)

References 25 publications

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“…S1 and S2 1 ). Once the snowpack starts to break-up, the bare ground advects heat onto the surrounding snowpack (Neumann and Marsh 1998). Assini and Young (2012) observed that the late-lying snowbeds located in the southern part of the Pass (north-facing) persisted longer than the northern ones, and often long after the wetland snowpack had disappeared.…”

Section: Snowmelt Durationmentioning

confidence: 99%

Snow cover variability at Polar Bear Pass, Nunavut

2018

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Information on arctic snow covers is relevant for climate and hydrology studies and investigations into the sustainability of both arctic fauna and flora. This study aims to (1) highlight the variability of snow cover at Polar Bear Pass (PBP) at a range of scales: point, local, and regional using both in situ snow cover measurements and remote sensing imagery products; and (2) consider how snow cover at PBP might change in the future. Terrain-based snow surveys documented the end-of-winter snowpacks over several seasons (2008)(2009)(2010)(2012)(2013), and snowmelt was measured daily at typical terrain types. MODIS products (snow cover) were used to document spatial snow cover variability across PBP and Bathurst and Cornwallis Islands. Due to limited data, no significant difference in snow cover duration can be identified at PBP over the period of record. Locally, end-of-winter snow cover does vary across a range of terrain types with snow depths and densities reflecting polar oasis sites. Aspect remains a defining factor in terms of snow cover variability at PBP. Northern areas of the Pass melt earlier. Regionally, PBP tends to melt out earlier than most of Bathurst Island. In the future, we surmise that snowpacks at PBP will be thinner and disappear earlier.

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Section: Snowmelt Durationmentioning

confidence: 99%

Snow cover variability at Polar Bear Pass, Nunavut

2018

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“…Possible causes include incomplete drainage of melt water from the lysimeters and/or advection influences from nearby exposed vegetation-a complicating factor that is not parameterized in SNTHERM (e.g. Neumann and Marsh, 1998). At the Cold Up open site; the regression line explained more of the variance for melt than for vapour fluxes (r 2 D 0Ð44 and 0Ð23), respectively (Figure 3c, d).…”

Section: Gravimetric and Sntherm Estimates Of Melt And Vapour Flux-opmentioning

confidence: 99%

Spatial variation of snowmelt and sublimation in a high‐elevation semi‐desert basin of western Canada

Jackson

Prowse

2009

Hydrological Processes

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Abstract:The Okanagan Basin, a semi-desert region of western Canada, is currently experiencing rapidly increasing pressure on its water resources from development and population increases, exacerbated by changes in climate. The major source of freshwater in the region originates from the melt of high-elevation snowpacks, about which little is currently known, including the proportion of the peak snowpack lost to sublimation. To better understand the hydrologic regime of this snow resource, a detailed field program was conducted during the 2007 snowmelt season. Specifically, peak annual snow distribution, ablation-season surfaceenergy exchange and mass balance were measured in a forested high-elevation catchment of the Okanagan Basin. During the snowmelt period, 1-4% of the peak annual snow-water equivalent (SWE) was lost to sublimation in open sites-averaging 0Ð4 mm d1 . Melt and sublimation rates increased significantly with elevation, and were observed to be higher and more variable in the open sites than under forest canopies. The largest sublimation events (>0Ð25 mm d 1 ) were associated with low atmospheric vapour pressure, temperatures below 0°C, and higher than average wind speeds. Condensation occurred under highly stable conditions in the boundary layer when sensible heat fluxes exceeded net radiative inputs to the snow surface. Melt rates were driven almost entirely by sensible heat fluxes and exceeded 30 mm d 1 during large-scale advection events. The results from this study will allow water managers to better predict the amount of water available for ecological, agricultural and municipal needs. This work also provides the basis for assessing changes in snow surface energetics due to ongoing salvage cutting in forested areas affected by the current mountain pine-beetle outbreak.

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“…These gradients are frequently rooted in differences between urban and rural energy balance and moisture sources [Arnfield, 2003]. Faster rates of snowmelt and local advection-assisted evapotranspiration have been reported in urban areas [Oke, 1979;Oke and McCaughey, 1983;Oke et al, 1992;Bengtsson and Westerström, 1992;Neumann and Marsh, 1998;Moriwaki and Kanda, 2004]. Energy flux partitioning in urban areas is sensitive to the Bowen ratio (ratio of sensible to latent heat flux), which is low following precipitation events [Offerle et al, 2006;Ward et al, 2013;Ramamurthy et al, 2014;Ao et al, 2016].…”

Section: Introductionmentioning

confidence: 99%

Urban emissions of water vapor in winter

et al. 2017

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Elevated water vapor (H2Ov) mole fractions were occasionally observed downwind of Indianapolis, IN, and the Washington, D.C.‐Baltimore, MD, area during airborne mass balance experiments conducted during winter months between 2012 and 2015. On days when an urban H2Ov excess signal was observed, H2Ov emission estimates range between 1.6 × 104 and 1.7 × 105 kg s−1 and account for up to 8.4% of the total (background + urban excess) advected flow of atmospheric boundary layer H2Ov from the urban study sites. Estimates of H2Ov emissions from combustion sources and electricity generation facility cooling towers are 1–2 orders of magnitude smaller than the urban H2Ov emission rates estimated from observations. Instances of urban H2Ov enhancement could be a result of differences in snowmelt and evaporation rates within the urban area, due in part to larger wintertime anthropogenic heat flux and land cover differences, relative to surrounding rural areas. More study is needed to understand why the urban H2Ov excess signal is observed on some days, and not others. Radiative transfer modeling indicates that the observed urban enhancements in H2Ov and other greenhouse gas mole fractions contribute only 0.1°C d−1 to the urban heat island at the surface. This integrated warming through the boundary layer is offset by longwave cooling by H2Ov at the top of the boundary layer. While the radiative impacts of urban H2Ov emissions do not meaningfully influence urban heat island intensity, urban H2Ov emissions may have the potential to alter downwind aerosol and cloud properties.

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Local advection of sensible heat in the snowmelt landscape of Arctic tundra

Cited by 66 publications

References 25 publications

Snow cover variability at Polar Bear Pass, Nunavut

Snow cover variability at Polar Bear Pass, Nunavut

Spatial variation of snowmelt and sublimation in a high‐elevation semi‐desert basin of western Canada

Urban emissions of water vapor in winter

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