Frost formation and frost meltwater drainage characteristics on aluminum surfaces with grooved structures
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Meltwater
Frost (temperature)
In order to demonstrate the spatial and temporal variations in meltwater chemistry at both the lysimeter (0.25 m 2 ) and basin scale, field measurements of snowmelt were conducted in northern Canada. These observations show that microscale variations in flow volume are accompanied by variations in meltwater chemistry. For example, the solute concentrations were largest in areas with low flow, while the largest mass flux occurred in the areas with highest flow. The observed variations in both concentration and mass flux can be quantitatively described by the relationships described by Hibberd [1984). The field measurements clearly demonstrate that in order to estimate the average meltwater chemistry, it is necessary to sample the flow field at a scale similar to that required to average the lateral variations in meltwater volume. Variations in meltwater runoff chemistry also occur at the basin scale due to changes in snowcover depth and the resulting differences in the timing of meltwater release. For example, at this site, meltwater release occurs up to a week earlier from the shallow snow covers than for the deeper snow covers. It would be expected that this asynchronous meltwater runoff would result in a smoothing of the ionic pulse at the basin scale, with lower peak values and a more gradual decline in concentration when compared with meltwater at a point.
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Snowmelt
Lysimeter
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The Isotope based Hydrograph Separation (IHS) has been instrumental in understanding the partitioning of streamflow sources and processes. However, uncertainties persist in the accuracy of IHS estimations and the appropriate definition and sampling of endmembers. To address these uncertainties, we used field data of snowpack, snowfall, and snow meltwater isotopes (δ18O) from Pallas, Northern Finland to estimate the total meltwater contribution during the snowmelt period. We investigated the biases resulting from the application of different sampling strategies for event water endmember. The total meltwater contribution to streamflow was 59.6 % (±2% uncertainty) using the time-variant rolling runoff-corrected melt flux-weighted meltwater 18O isotope value. However, replacing it with either snowfall or winter snowpack 18O isotope weighted average values underestimated the meltwater contribution by 17.8 % or 22.6 %, respectively. Conversely, using time-variant instantaneous meltwater 18O isotope values overestimated the meltwater contribution by only 1.5 %. These discrepancies highlight the importance of choosing the appropriate endmember isotopes in IHS. The large differences in meltwater contribution for a 2-week peak discharge period based on different endmembers can lead to different interpretations of hydrological, ecohydrological, and biogeochemical processes. Thus, to better understand streamflow generation processes, we suggest using rolling runoff-corrected meltwater 18O or 2H isotope values in the IHS. In the absence of meltwater samples, the 18O or 2H isotope values of snowpack samples during the peak melt season may provide reasonable estimates of the meltwater contribution, with some minor underestimations. Our study highlights the importance of appropriate event meltwater endmember selection and sampling methodology for the IHS.
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Snowmelt
Snowpack
δ18O
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Abstract. We identify and map visible traces of subglacial meltwater drainage around the former Keewatin Ice Divide, Canada, from high-resolution Arctic Digital Elevation Model (ArcticDEM) data. We find similarities in the characteristics and spatial locations of landforms traditionally treated separately (i.e. meltwater channels, meltwater tracks and eskers) and propose that creating an integrated map of meltwater routes captures a more holistic picture of the large-scale drainage in this area. We propose the grouping of meltwater channels and meltwater tracks under the term meltwater corridor and suggest that these features in the order of 10s–100s m wide, commonly surrounding eskers and transitioning along flow between different types, represent the interaction between a central conduit (the esker) and surrounding hydraulically connected distributed drainage system (the meltwater corridor). Our proposed model is based on contemporary observations and modelling which suggest that connections between conduits and the surrounding distributed drainage system within the ablation zone occur as a result of overpressurisation of the conduit. The widespread aerial coverage of meltwater corridors (5 %–36 % of the bed) provides constraints on the extent of basal uncoupling induced by basal water pressure fluctuations. Geomorphic work resulting from repeated connection to the surrounding hydraulically connected distributed drainage system suggests that basal sediment can be widely accessed and evacuated by meltwater.
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Electrical conduit
Landform
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<p>Budyko framework has been widely used to estimate the partitioning of precipitation into evapotranspiration and runoff as a function of an aridity index (i.e., ratio of potential evapotranspiration to precipitation) in catchments where snow or glaciers are absent. Where snow or glaciers exist, meltwater from either may considerably affect the performance of the Budyko framework. However such effects have not been investigated in the Xinjiang territory of Northwest China, which features many meltwater-dependent river systems. To analyze the effects of meltwater on hydrological cycles in Xinjiang, we utilized a calibrated hydrological model (Soil and Water Assessment Tool, SWAT) to estimate meltwater from snow or glaciers. The water budgets of 21 catchments across three major mountain ranges of Xinjiang showed that normalized contributions of meltwater to river runoff were respectively 89.9%, 77.0%, and 55.6% in the catchments of Altay, Kunlun and Tienshan Mountains. The results showed that the catchments of Altay Mountains with the highest meltwater ratio (defined as the ratio of meltwater to the sum of meltwater and rainfall, 0.572 &#177; 0.075) had the lowest Budyko parameter &#969; (1.238), while those of Tienshan Mountains with the lowest meltwater ratio (0.239 &#177; 0.143) had the highest &#969; value (1.348). This indicated that the Budyko parameter &#969; was negatively correlated to meltwater ratio across three mountains. Incorporating meltwater from snow and glaciers into the Budyko framework significantly increased the values of &#969; in all three mountain ranges, indicating that the Budyko framework without inclusion of meltwater could under-estimate evapotranspiration in Xinjiang, China. There results derived from this research also implied that both surface runoff and evapotranspiration may increase under a warming climate in mountain areas.</p>
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Abstract Determining the injection of glacial meltwater into polar oceans is crucial for quantifying the climate system response to ice sheet mass loss. However, meltwater is poorly observed and its pathways poorly known, especially in winter. Here we present winter meltwater distribution near Pine Island Glacier using data collected by tagged seals, revealing a highly variable meltwater distribution with two meltwater-rich layers in the upper 250 m and at around 450 m, connected by scattered meltwater-rich columns. We show that the hydrographic signature of meltwater is clearest in winter, when its presence can be unambiguously mapped. We argue that the buoyant meltwater provides near-surface heat that helps to maintain polynyas close to ice shelves. The meltwater feedback onto polynyas and air-sea heat fluxes demonstrates that although the processes determining the distribution of meltwater are small-scale, they are important to represent in Earth system models.
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Iceberg
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Translatory flow is observed in a ground water runoff during a rainstorm. Layered snow cover is considered to play the same role as soil layer for water runoff. The purpose of this paper is to report the translatory flow phenomena of snow meltwater in a snowpack. Studies on the snowmelt runoff in a snowpack were carried out at eastern Canada and Hokkaido. In the case of Canada, the hydrograph of snowmelt is separated into "old water" (meltwater in the lower snowpack) and "new water" (meltwater percolated from surface snow layer) by the concentration of NO3-. The concentration of NO 3- in meltwater in the lower snowpack is estimated to be higher than that in meltwater generated from the surface snow layer. Separated "old water" is the major component of early snowmelt runoff during a day. This quick response of the meltwater in the lower snowpack requires a translatory flow mechanism in the snowpack. "New water" is the major component of the recession limb of the hydrograph. The same phenomena were observed at Moshiri, Hokkaido, during the 1988 snowmelt. Two peaks on the meltwater hydrograph were observed. The first peak is composed of the meltwater in the lower snowpack; the major component of the second peak is the meltwater percolated from the surface snow layer. The translatory phenomenon in a snowpack is not observed when the depth of snow cover is not so thick.
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Snowpack
Snowmelt
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The primary cause of the large landslide in Hachimantai, Akita Prefecture on May 11, 1997 is considered to be heavy rainfall of 110 mm/day on the 8 th three days prior to the landslide. However, the occurrence of this landslide cannot be explained by this rainfall alone because such events occur every 7 to 8 years, according to the Gambel-Chow method for the last 19 years meteorological data. In addition to the heavy rainfall, continuously supplied meltwater from snow pack is also thought to have played an important role in the occurrence of this landslide. Therefore, we estimated the rate of meltwater flow by the heat balance method using the AMeDAS data set of the Meteorological Agency to clarify the meltwater conditions prior to the landslide. Our calculations showed that the 30-50 mm/day of meltwater in late April rose to 40-60 mm/day in the beginning of May due to the seasonal increase of heat fluxes. On May 8, 170 mm of water which consisted of 110 mm of rainfall and 60 mm of meltwater was assumed to have flowed out from the snow pack to the ground. As a result of calculations of meltwater for 19 years and subsequent comparision between meltwater and rainfall of each year and analysis of probable distribution of the annual maximum daily values, it was revealed that the 170 mm of [meltwater+rainfall] flow on May 8 occurs only once every 70-80 years.
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Abstract The Greenland Ice Sheet has been, and will continue, losing mass at an accelerating rate. The influence of this anomalous meltwater discharge on the regional and large‐scale ocean could be considerable but remains poorly understood. This uncertainty is in part a consequence of challenges in observing water mass transformation and meltwater spreading in coastal Greenland. Here we use tracer observations that enable unprecedented quantification of the export, mixing, and vertical distribution of meltwaters leaving one of Greenland's major glacial fjords. We find that the primarily subsurface meltwater input results in the upwelling of the deep fjord waters and an export of a meltwater/deepwater mixture that is 30 times larger than the initial meltwater release. Using these tracer data, the vertical structure of Greenland's summer meltwater export is defined for the first time showing that half the meltwater export occurs below 65 m.
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Fjord
Greenland ice sheet
Iceberg
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