Melt and surface sublimation across a glacier in a dry environment: distributed energy-balance modelling of Juncal Norte Glacier, Chile

Ayala, Álvaro; Pellicciotti, Francesca; Peleg, Nadav; Burlando, Paolo

doi:10.1017/jog.2017.46

Cited by 37 publications

(39 citation statements)

References 94 publications

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“…Although 285 this implies that the model is not strictly mass-conserving, we verify that the discarded snow is in average 34 mm yr -1 over the entire basin (or 688 mm yr -1 = 1.9 mm d -1 over the areas above 5000 m a.s.l. ), which is a reasonable estimate of sublimation amounts for this region (Corripio, 2003;Ayala et al, 2017b), and is in the order of the model uncertainties (see Figure 2). Table 1, whereas values for the sub-surface flux parameters are shown in the supplementary information (Table S1).…”

Section: Model Setup For the Maipo River Basinsupporting

confidence: 58%

“…However, the representation of processes driving the mass balance at some specific sites requires more fundamental work, and additional parameterizations or more physicallybased representations are required. Such sites correspond mainly to sublimation-dominated sites above 5500 m a.s.l., where the temperature-index modelling is inaccurate (Ayala et al, 2017a(Ayala et al, , 2017b, debris-covered areas with complex distributions of debris thickness (Burger et al, 2018a), or steep glacierized slopes such as the volcanoes in the Maipo River Basin. 535…”

Section: Uncertainties In the Modelling Of Glacier Changes In Data-scmentioning

confidence: 99%

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Glacier runoff variations since 1955 in the Maipo River Basin, semiarid Andes of central Chile

Ayala¹,

Farías-Barahona²,

Huss³

et al. 2019

Preprint

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Abstract. As glaciers adjust their size in response to climate variations, long-term changes in meltwater production can be expected, affecting the local availability of water resources. We investigate glacier runoff in the period 1955–2016 in the Maipo River Basin (4 843 km2), semiarid Andes of Chile. The basin contains more than 800 glaciers covering 378 km2 (inventoried in 2000). We model the mass balance and runoff contribution of 26 glaciers with the physically-oriented and fully-distributed TOPKAPI-ETH glacio-hydrological model, and extrapolate the results to the entire basin. TOPKAPI-ETH is run using several glaciological and meteorological datasets, and its results are evaluated against streamflow records, remotely-sensed snow cover and geodetic mass balances for the periods 1955–2000 and 2000–2013. Results show that glacier mass balance had a general decreasing trend as a basin average, but with differences between the main sub-catchments. Glacier volume decreased by one fifth (from 18.6 ± 4.5 to 14.9 ± 2.9 km3). Runoff from the initially glacierized areas was 186 ± 27 mm yr−1 (17 ± 7 % of the total contributions to the basin), but it shows a decreasing sequence of maxima, which can be linked to the interplay between a decrease in precipitation since the 1980s and the reduction of ice melt. If glaciers in the basin were in equilibrium with the climate of the last two decades, their volume would be reduced to 81 ± 38 % of the year 2000 volume, and glacier runoff during dry periods would be 61 ± 24 % of its maximum contribution in the period 1955–2016, considerably decreasing the drought mitigation capacity of the basin.

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Section: Model Setup For the Maipo River Basinsupporting

confidence: 58%

Section: Uncertainties In the Modelling Of Glacier Changes In Data-scmentioning

confidence: 99%

Glacier runoff variations since 1955 in the Maipo River Basin, semiarid Andes of central Chile

Ayala¹,

Farías-Barahona²,

Huss³

et al. 2019

Preprint

Self Cite

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“…The relative contribution of ice ablation to the total ablation between October 2017 and January 2018 was modeled assuming that there was no difference in the snow coverage between the PLE_Snow ON acquisition (September 2017) and the date of probe measurements of snow depth (October 2017). Spatially interpolated probe depths on the glaciers (section ) were used to initialize a distributed energy balance model based upon Ayala et al () to calculate the total amount ice ablation across the glacier, forced by temporary on‐glacier AWSs and validated against distributed ablation stakes (Figure ). Quantities of ice ablation (converted to a surface height change based upon measured snow density and the assumed 900 kg m 3 density of ice) were added to the PLE_Snow OFF DEM in order reduce snow depths for areas associated with subsequent ice ablation.…”

Section: Methodsmentioning

confidence: 99%

Snow Depth Patterns in a High Mountain Andean Catchment from Satellite Optical Tristereoscopic Remote Sensing

Shaw

Gascoin

Mendoza

et al. 2020

Water Resources Research

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Obtaining detailed information about high mountain snowpacks is often limited by insufficient ground‐based observations and uncertainty in the (re)distribution of solid precipitation. We utilize high‐resolution optical images from Pléiades satellites to generate a snow depth map, at a spatial resolution of 4 m, for a high mountain catchment of central Chile. Results are negatively biased (median difference of −0.22 m) when compared against observations from a terrestrial Light Detection And Ranging scan, though replicate general snow depth variability well. Additionally, the Pléiades dataset is subject to data gaps (17% of total pixels), negative values for shallow snow (12%), and noise on slopes >40–50° (2%). We correct and filter the Pléiades snow depths using surface classification techniques of snow‐free areas and a random forest model for data gap filling. Snow depths (with an estimated error of ~0.36 m) average 1.66 m and relate well to topographical parameters such as elevation and northness in a similar way to previous studies. However, estimations of snow depth based upon topography (TOPO) or physically based modeling (DBSM) cannot resolve localized processes (i.e., avalanching or wind scouring) that are detected by Pléiades, even when forced with locally calibrated data. Comparing these alternative model approaches to corrected Pléiades snow depths reveals total snow volume differences between −28% (DBSM) and +54% (TOPO) for the catchment and large differences across most elevation bands. Pléiades represents an important contribution to understanding snow accumulation at sparsely monitored catchments, though ideally requires a careful systematic validation procedure to identify catchment‐scale biases and errors in the snow depth derivation.

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“…Both the profile method and the bulk method have been applied to quantify turbulent fluxes and sublimation (e.g., Ayala et al, ; Conway & Cullen, ; Herrero & Polo, ). Compared to the profile method, the bulk method is more widely used because it is insensitive to observation errors (Munneke et al, ; Yang et al, ).…”

Section: Introductionmentioning

confidence: 99%

Simple Parameterization of Aerodynamic Roughness Lengths and the Turbulent Heat Fluxes at the Top of Midlatitude August‐One Glacier, Qilian Mountains, China

Guo

Chen

et al. 2018

JGR Atmospheres

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The fluxes of sensible heat (H) and latent heat (LE), which are generally the important parts of the energy and mass balances over glacier surfaces, are widely quantified by the bulk method. However, due to the difficulty of determining the aerodynamic roughness length z 0m in this method, H and LE values may still have large uncertainties with significant inaccuracy. To acquire reliable varying and intrinsic z 0m values, new simpler parameterizations for z 0m values at different ranges of the friction velocity u *b were fitted in this study. The method was implemented using the related meteorological data and glacial sublimation/condensation measured at the top of the August-one glacier (4817 m asl) in the Qilian Mountains from 1 July 2016 to 15 August 2017. The parameterization shows that z 0m increased sharply when u *b exceeded 0.43 m/s (the approximate threshold value) and that the effect of snowdrift was slight for the hourly z 0m values in the range 0.15 ≤ u *b ≤ 0.43 m/s, which could thus be used to calculate the daily z 0m . During the wet period (, the turbulent fluxes calculated by the bulk method showed that net radiation R net was the primary source of surface energy (60.7 w/m 2 ), whereas during the dry period (25 September 2016 to 4 May 2017), the main heat sink was the positive H (28.5 w/m 2 ) rather than the negative R net (À10.0 w/m 2 ). Plain Language SummaryThe profile method and the bulk method have been applied to quantify turbulent fluxes and sublimation/condensation, and the bulk method is more widely used because it is insensitive to observation errors. However, determination of the aerodynamic roughness lengths in the bulk method remains a large challenge. So we tried to acquire reliable varying and intrinsic roughness length for momentum through its parametric analysis. The related meteorological data and glacial sublimation/ condensation were measured over a mountain glacier. Hourly roughness lengths in the transitional range affected slightly by snowdrift were found with the approximate threshold value. The comparison provided here verifies that these values are reliable, although this method is relatively rough. The z 0m parameterization can be regarded as an important basis of turbulent heat flux research. Therefore, in addition to z 0m parameterization, it can also be very meaningful to further discuss the temporal variation of meteorology and turbulent heat fluxes. Further research is needed and very important to improve our understanding of energy and mass exchange between the glacier surface and atmosphere, especially in arid and semiarid regions.

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Melt and surface sublimation across a glacier in a dry environment: distributed energy-balance modelling of Juncal Norte Glacier, Chile

Cited by 37 publications

References 94 publications

Glacier runoff variations since 1955 in the Maipo River Basin, semiarid Andes of central Chile

Glacier runoff variations since 1955 in the Maipo River Basin, semiarid Andes of central Chile

Snow Depth Patterns in a High Mountain Andean Catchment from Satellite Optical Tristereoscopic Remote Sensing

Simple Parameterization of Aerodynamic Roughness Lengths and the Turbulent Heat Fluxes at the Top of Midlatitude August‐One Glacier, Qilian Mountains, China

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