Subglacial drainage system structure and morphology of Brewster Glacier, New Zealand

Willis, Ian; Lawson, Wendy; Owens, I. F.; Jacobel, Bob; Autridge, Jenny

doi:10.1002/hyp.7146

Cited by 37 publications

(58 citation statements)

References 74 publications

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“…Mean tracer transit velocity over the whole ablation season was 0.294 m/s and varied between 0.148 m/s (10 April) and 0.555 m/s (1 July). The maximum and minimum velocities we observed here were within the ranges of previous reported experiments carried out at other temperate glaciers [19,20,26,41,43].…”

Section: Subglacial Drainage System Characteristic Indicated By Dye Tsupporting

confidence: 90%

“…The dye-investigated section of the subglacial channel could exist all around year due to the uninterrupted water inflow from one of the larger tributary streams fed by two glaciers on the south side of the catchment. Since the ice flow of the lower ablation area of the Hailuogou Glacier is constrained by the lateral terrains and the ice tongue extends longitudinally along the valley trough with a width less than 400 m, the subglacial drainage network is therefore limited longitudinally and without much development of lateral dendritic tributaries as those reported for glaciers with a wider ablation area [20,26,41,42]. All measured tracer concentrations reached the highest detected value (3.08 to 10.65 µg·L −1 ) in less than 3 h (0.57 to 3.00 h) and receded back to the background value (<0.1 µg·L −1 ) in about 5 to 10 h after injection.…”

Section: Subglacial Drainage System Characteristic Indicated By Dye Tmentioning

confidence: 93%

“…Subglacial drainage system evolution of some mountain glaciers is conceptualized as a morphological transition from a slow or distributed drainage network to a fast or channelized drainage system over the course of the melt season [19,20]. This transition induces subglacial hydraulic changes and therefore could be indicated by the tracing experiments, which have been widely used in the study of englacial and subglacial drainage system development and evolution (e.g., [21][22][23][24][25][26]).…”

Section: Introductionmentioning

confidence: 99%

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Seasonal Variation of Drainage System in the Lower Ablation Area of a Monsoonal Temperate Debris-Covered Glacier in Mt. Gongga, South-Eastern Tibet

Liu

Cao³

2018

Water

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Seasonal evolution of the subglacial drainage system in the lower ablation area of the Hailuogou glacier ice tongue were revealed by repeated dye tracer (Rhodamine WT) experiments during the 2009 ablation season. Between April and October, 18 dye tracer experiments were conducted by injecting the tracer at one location of the lower ablation area of the Hailuogou Glacier to diagnose the seasonal variation of the subglacial drainage system of this section of glacier ice tongue. Using a simple advection-dispersion model (ADM), the flow velocity, hydrodynamic dispersion coefficient, and degree of tracer spreading were deduced. Tracer transit velocity through the tested subglacial channel varied from 0.148 to 0.555 m s −1 during the 2009 ablation season. Dispersivity showed a relatively high value than that found at other glaciers, which varied between 27.05 and 287.49 m 2 s −1 . Seasonal changes of these indexes indicated that the subglacial drainage system of the lower ablation area of the Hailougou Glacier is a relatively stable existing system in the case of its longitudinal shape, whereas its hydraulic efficiency is low in the early and late ablation seasons and high during the middle of summer due to subglacial channel expansion.

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Section: Subglacial Drainage System Characteristic Indicated By Dye Tsupporting

confidence: 90%

Section: Subglacial Drainage System Characteristic Indicated By Dye Tmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Seasonal Variation of Drainage System in the Lower Ablation Area of a Monsoonal Temperate Debris-Covered Glacier in Mt. Gongga, South-Eastern Tibet

Liu

Cao³

2018

Water

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“…To characterise and model the spatial structure of snow depth, we assume that the offset snow depth data stem from the realisation of a random function (Wackernagel, 2003), which we define here as a snow depth index (SDI). This provides us with a platform from which to apply a multi-variate geostatistical approach to resolve the spatial variability in snow depth.…”

Section: Creating a Snow-depth Indexmentioning

confidence: 99%

An 11-year record of mass balance of Brewster Glacier, New Zealand, determined using a geostatistical approach

et al. 2016

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ABSTRACT. Recognising the scarcity of glacier mass-balance data in the Southern Hemisphere, a massbalance measurement programme was started at Brewster Glacier in the Southern Alps of New Zealand in 2004. Evolution of the measurement regime over the 11 years of data recorded means there are differences in the spatial density of data obtained. To ensure the temporal integrity of the dataset a new geostatistical approach is developed to calculate mass balance. Spatial co-variance between elevation and snow depth allows a digital elevation model to be used in a co-kriging approach to develop a snow depth index (SDI). By capturing the observed spatial variability in snow depth, the SDI is a more reliable predictor than elevation and is used to adjust each year of measurements consistently despite variability in sampling spatial density. The SDI also resolves the spatial structure of summer balance better than elevation. Co-kriging is used again to spatially interpolate a derived mean summer balance index using SDI as a co-variate, which yields a spatial predictor for summer balance. The average glacier-wide surface winter, summer and annual balances over the period 2005-15 are 2484, −2586 and −102 mm w.e., respectively, with changes in summer balance explaining most of the variability in annual balance.

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“…To make a first quantitative estimate of volume and mass change, a GPS survey conducted in January 1997 up to the foot of the steep north-eastern slopes (Willis et al, 2009) is compared to the 1986 topography derived from photogrammetry of imagery captured in February 1986 (see Columbus et al, 2011), which reveals substantial changes in surface elevation (Fig. 15).…”

Section: Brewster Mass Balance Recordmentioning

confidence: 99%

Reconstructing the mass balance of Brewster Glacier, New Zealand, using MODIS-derived glacier-wide albedo

et al. 2016

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Abstract. In New Zealand, direct measurements of mass balance are sparse due to the inaccessibility of glaciers in the Southern Alps and the logistical difficulties associated with maintaining a mass balance record. In order to explore the benefit of remotely sensed imaging to monitor mass balance in the Southern Alps, this research assesses the relationship between measurements of glacier surface albedo derived from Moderate Resolution Imaging Spectroradiometer (MODIS) and mass balance observations using the glaciological method on Brewster Glacier over the 2005-2013 period. We confirm that minimum glacier-wide albedo is a reliable predictor for annual mass balance in this maritime environment (R 2 = 0.93). Furthermore, we show that regular monitoring of glacier-wide albedo enables a new metric of winter accumulation to be derived, namely the cumulative winter albedo, which is found to correlate strongly with winter mass balance (R 2 = 0.88), thus enabling the reconstruction of separate winter and summer mass balance records. This allows the mass balance record for Brewster Glacier to be extended back to the start of MODIS observations in 2000 and to confirm that the annual balance of Brewster Glacier is largely controlled by summer balance (R 2 = 92 %). An application of the extended record is proposed whereby the relationship between mass balance and the photographic record of the end-of-summer snowline altitude is assessed. This allowed the annual balance record of Brewster Glacier to be reconstructed over the period 1977-2013, thus providing the longest record of mass balance for a glacier in New Zealand.Over the 37-year period, our results show that Brewster Glacier gained a significant mass of up to 14.5 ± 2.7 m w.e. by 2007. This gain was offset by a marked shift toward negative balances after 2008, yielding a loss of 5.1 ± 1.2 m w.e., or 35 % of the gain accumulated over the previous 30 years. The good correspondence between mass balance of Brewster Glacier and the phase of the Pacific (Inter-)Decadal Oscillation (PDO/IPO), associated with the fast terminus retreat observed between 1978 and 1998, strongly suggests that the observed mass gain of Brewster Glacier since 1977 is only offsetting a longer sequence of dominantly negative balances.

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Subglacial drainage system structure and morphology of Brewster Glacier, New Zealand

Cited by 37 publications

References 74 publications

Seasonal Variation of Drainage System in the Lower Ablation Area of a Monsoonal Temperate Debris-Covered Glacier in Mt. Gongga, South-Eastern Tibet

Seasonal Variation of Drainage System in the Lower Ablation Area of a Monsoonal Temperate Debris-Covered Glacier in Mt. Gongga, South-Eastern Tibet

An 11-year record of mass balance of Brewster Glacier, New Zealand, determined using a geostatistical approach

Reconstructing the mass balance of Brewster Glacier, New Zealand, using MODIS-derived glacier-wide albedo

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