@article{21837, abstract = {In a warming world of glacier changes, the scientific community has dedicated increasing attention to debris-covered glaciers and their response to climate. A variety of models with distinct complexity and data requirements have been developed and widely used to simulate melt under debris at different sites and scales, but their skills have never been compared. As part of the activities of the International Association of Cryospheric Sciences (IACS) Debris Covered Glacier Working Group, we present an intercomparison exercise aimed at advancing our understanding of model skills in simulating ice melt under a debris layer. We compare 15 models with different complexity at nine sites in the European Alps, Caucasus, Chilean Andes, Nepalese Himalaya and the Southern Alps of New Zealand, over one melt season. We run the models with measured meteorological data from automatic weather stations and estimated or measured debris properties. We consider four main model categories: (i) energy balance models that calculate melt by solving the physics of heat transfer to the debris layer, but require a high amount of input data; (ii) a simplified energy balance model; (iii) enhanced temperature-index models; and (iv) simple empirical temperature-index models that have been extensively used given their low data requirement but require calibration of their empirical parameters. Model performance is evaluated using on-site measurements of sub-debris melt (for all models) and surface temperature (for models based on the surface energy balance). Our results show that physically-based energy balance models and empirical temperature-index models perform in a distinct manner. At one end of the spectrum, simple temperature-index models are accurate when recalibrated or when using site-specific literature parameters, and show poor results when parameters are uncalibrated. At the other end, energy balance models show a range of performance: the most accurate energy balance models are those with the highest degree of complexity at the atmosphere-debris interface. An important data gap emerged from our experiment: the poor performance of all models at three sites was related to the poor knowledge of debris properties, and specifically of thermal conductivity. Future work should focus on both: (i) consistent data acquisition to evaluate existing models and support new model developments; (ii) advancing models by accounting for processes such as debris-snow interactions, moisture in the debris and refreezing. We suggest that a systematic effort of model development using a common model framework could be carried out in phase II of the Working Group.}, author = {Pellicciotti, Francesca and Fontrodona-Bach, Adrià and Rounce, David R. and Fyffe, Catriona Louise and Anderson, Leif S. and Ayala, Álvaro and Brock, Ben W. and Buri, Pascal and Fugger, Stefan and Fujita, Koji and GANTAYAT, PRATEEK and Groos, Alexander R. and Immerzeel, Walter and Kneib, Marin and Mayer, Christoph and MacDonell, Shelley and McCarthy, Michael and McPhee, James and Miles, Evan and Purdie, Heather and Rets, Ekaterina and Sakai, Akiko and Shaw, Thomas and Steiner, Jakob and Wagnon, Patrick and Winter-Billington, Alex}, issn = {1994-0424}, journal = {The Cryosphere}, number = {3}, pages = {1895--1928}, publisher = {Copernicus Publications}, title = {{DCG-MIP: The debris-covered glacier melt model intercomparison experiment}}, doi = {10.5194/tc-20-1895-2026}, volume = {20}, year = {2026}, } @article{21247, abstract = {Seasonal snowmelt in High Mountain Asia is an important source of river discharge. Therefore, observation of the spatiotemporal variations in snow cover at catchment scales using high-resolution satellites is essential for understanding changes in water supply from headwater catchments. In this study, we adapt an algorithm to automatically detect the snowline altitude (SLA) using the Google Earth Engine platform with available high-resolution multispectral satellite archives that can be readily applied for areas of interest. Here, we applied and evaluated the tool to five glacierized watersheds across the Himalayas to quantify the changes in seasonal and annual snow cover over the past 21 years and analyze climate reanalysis data to assess the meteorological factors influencing the SLA. Our findings revealed substantial variations in the SLA among sites in terms of seasonal patterns, decadal trends, and meteorological controls. We identify positive trends in SLA in Hidden Valley (+11.9 m yr−1), Langtang (+14.4 m yr−1), and Rolwaling (+8.2 m yr−1) in the Nepalese Himalayas but a negative trend in Satopanth (−15.6 m yr−1) in the western Indian Himalayas and no significant trend in Parlung in southeastern Tibet. We suggest that the increase in SLA in Nepal was caused by warmer temperatures during the monsoon season, whereas the decrease in SLA in India was driven by increased winter snowfall and reduced monsoon snowmelt. By integrating the outcomes of these analyses, we found that long-term changes in SLA are primarily driven by shifts in the local climate, whereas seasonal variability may be influenced by geographic features in conjunction with climate.}, author = {Sasaki, Orie and Miles, Evan S. and Pellicciotti, Francesca and Sakai, Akiko and Fujita, Koji}, issn = {1994-0424}, journal = {The Cryosphere}, number = {11}, pages = {5283--5298}, publisher = {Copernicus Publications}, title = {{Contrasting patterns of change in snowline altitude across five Himalayan catchments}}, doi = {10.5194/tc-19-5283-2025}, volume = {19}, year = {2025}, } @article{18985, abstract = {Persistent multiyear drought (MYD) events pose a growing threat to nature and humans in a changing climate. We identified and inventoried global MYDs by detecting spatiotemporally contiguous climatic anomalies, showing that MYDs have become drier, hotter, and led to increasingly diminished vegetation greenness. The global terrestrial land affected by MYDs has increased at a rate of 49,279 ± 14,771 square kilometers per year from 1980 to 2018. Temperate grasslands have exhibited the greatest declines in vegetation greenness during MYDs, whereas boreal and tropical forests have had comparably minor responses. With MYDs becoming more common, this global quantitative inventory of the occurrence, severity, trend, and impact of MYDs provides an important benchmark for facilitating more effective and collaborative preparedness toward mitigation of and adaptation to such extreme events.}, author = {Chen, Liangzhi and Brun, Philipp and Buri, Pascal and Fatichi, Simone and Gessler, Arthur and Mccarthy, Michael and Pellicciotti, Francesca and Stocker, Benjamin and Karger, Dirk Nikolaus}, issn = {1095-9203}, journal = {Science}, number = {6731}, pages = {278--284}, publisher = {AAAS}, title = {{Global increase in the occurrence and impact of multiyear droughts}}, doi = {10.1126/science.ado4245}, volume = {387}, year = {2025}, } @article{19777, abstract = {Snow cover is of key importance for water resources in high mountain Asia (HMA) and is expected to undergo extensive changes in a warming climate. Past studies have quantified snow cover changes with satellite products of relatively low spatial resolution (∼500 m) which are hindered by the steep topography of this mountain region. We derive snowlines from Sentinel-2 and Landsat 5, 7 and 8 images, which, thanks to their higher spatial resolution, are less sensitive to the local topography. We calculate the snow line altitude (SLA) and its seasonality for all glacierized catchments of HMA and link these patterns to climate variables corrected for topographic biases. As such, the snowline changes provide a clear proxy for climatic changes. Our results highlight a strong spatial variability in mean SLA and in its seasonal changes, including across mountain chains and between the monsoon-dominated and the westerlies-dominated catchments. Over the period 1999–2019, the western regions of HMA (Pamir, Karakoram, Western Himalaya) have undergone increased snow coverage, expressed as seasonal SLA decrease, in spring and summer. This change is opposed to a widespread increase in SLA in autumn across the region, and especially the southeastern regions of HMA (Nyainqentanglha, Hengduan Shan, South–East Himalaya). Our results indicate that the diversity of seasonal snow dynamics across the region is controlled not by temperature or precipitation directly but by the timing and partitioning of solid precipitation. Decadal snowline changes (1999–2009 vs 2009–2019) seasonally precede temperature changes, suggesting that seasonal temperature changes in the Karakoram–Pamir and Eastern Nyainqentanglha regions may have responded to snow cover changes, rather than driving them.}, author = {Bernat, M. and Miles, E. S. and Kneib, M. and Fujita, K. and Sasaki, O. and Shaw, Thomas and Pellicciotti, Francesca}, issn = {1748-9326}, journal = {Environmental Research Letters}, number = {6}, publisher = {IOP Publishing}, title = {{Precipitation phase drives seasonal and decadal snowline changes in high mountain Asia}}, doi = {10.1088/1748-9326/adcf39}, volume = {20}, year = {2025}, } @article{19839, abstract = {The snow and glaciers of the Peruvian Andes provide vital water supplies in a region facing water scarcity and substantial glacier change. However, there remains a lack of understanding of snow processes and quantification of the contribution of melt to runoff. Here we apply a distributed glacio-hydrological model over the Rio Santa basin to disentangle the role of the cryosphere in the Andean water cycle. Only at the highest elevations (>5000 m a.s.l.) is the snow cover continuous; at lower elevations, the snowpack is thin and ephemeral, with rapid cycles of snowfall and melt. Due to the large catchment area affected by ephemeral snow, its contribution to catchment inputs is substantial (23% and 38% in the wet and dry season, respectively). Ice melt is crucial in the mid-dry season (up to 44% of inputs). Our results improve estimates of water fluxes and call for further process-based modelling across the Andes.}, author = {Fyffe, Catriona Louise and Potter, Emily and Miles, Evan and Shaw, Thomas and Mccarthy, Michael and Orr, Andrew and Loarte, Edwin and Medina, Katy and Fatichi, Simone and Hellström, Rob and Baraer, Michel and Mateo, Emilio and Cochachin, Alejo and Westoby, Matthew and Pellicciotti, Francesca}, issn = {2662-4435}, journal = {Communications Earth and Environment}, publisher = {Springer Nature}, title = {{Thin and ephemeral snow shapes melt and runoff dynamics in the Peruvian Andes}}, doi = {10.1038/s43247-025-02379-x}, volume = {6}, year = {2025}, } @article{19878, abstract = {Rock debris partially covers glaciers worldwide, with varying extents and distributions, and controls sub‐debris melt rates by modifying energy transfer from the atmosphere to the ice. Two key physical properties controlling this energy exchange are thermal conductivity (k) and aerodynamic roughness length (z0). Accurate representation of these properties in energy‐balance models is critical for understanding climate‐glacier interactions and predicting the behavior of debris‐covered glaciers. However, k and z0 have been derived at very few sites from limited local measurements, using different approaches, and most model applications rely on values reported from these few sites and studies. We derive k and z0 using established and modified approaches from data at three locations on Pirámide Glacier in the central Chilean Andes. By comparing methods and evaluating melt simulated with an energy‐balance model, we reveal substantial differences between approaches. These lead to discrepancies between ice melt from energy‐balance simulations and observed data, and highlight the impact of method choice on calculated ice melt. Optimizing k against measured melt appears a viable approach to constrain melt simulations. Determining z0 seems less critical, as it has a smaller impact on total melt. Profile aerodynamic method measurements for estimating z0, despite higher costs, are independent of ice melt calculations. The large, unexpected differences between methods indicate a substantial knowledge gap. The fact that field‐derived k and z0 fail to work well in energy‐balance models, suggests that model values represent bulk properties distinct from theoretical field measurements. Addressing this gap is essential for improving glacier melt predictions.}, author = {Melo Velasco, Juan Vicente and Miles, Evan and McCarthy, Michael and Shaw, Thomas and Fyffe, Catriona Louise and Fontrodona-Bach, Adrià and Pellicciotti, Francesca}, issn = {2169-9011}, journal = {Journal of Geophysical Research: Earth Surface}, number = {6}, publisher = {Wiley}, title = {{Method dependence in thermal conductivity and aerodynamic roughness length estimates on a debris‐covered glacier}}, doi = {10.1029/2025jf008360}, volume = {130}, year = {2025}, } @article{20348, abstract = {Central Asia hosts some of the world’s last relatively healthy mountain glaciers and is heavily dependent on snow and ice melt for downstream water supply, though the causes of this stable glacier state are not known. We combine recent in-situ observations, climate reanalysis and remote sensing data to force a land-surface model to reconstruct glacier changes over the last two decades (1999–2023) and disentangle their causes over a benchmark glacierized catchment in Tajikistan. We show that snowfall and snow depth have been substantially lower since 2018, leading to a decline in glacier health and reduced runoff generation. Remote-sensing observations confirm wider snow depletion across the Northwestern Pamirs, suggesting that a lack of snowfall might be a cause of mass losses regionally. Our results provide an explanation for the recent decline in glacier health in the region, and reinforce the need to better understand the variability of precipitation.}, author = {Jouberton, Achille and Shaw, Thomas and Miles, Evan and Kneib, Marin and Fugger, Stefan and Buri, Pascal and Mccarthy, Michael and Kayumov, Abdulhamid and Navruzshoev, Hofiz and Halimov, Ardamehr and Kabutov, Khusrav and Homidov, Farrukh and Pellicciotti, Francesca}, issn = {2662-4435}, journal = {Communications Earth and Environment}, publisher = {Springer Nature}, title = {{Snowfall decrease in recent years undermines glacier health and meltwater resources in the Northwestern Pamirs}}, doi = {10.1038/s43247-025-02611-8}, volume = {6}, year = {2025}, } @article{20480, abstract = {Recent studies have argued that air temperatures over many mountain glaciers are decoupled from their surroundings, leading to a local cooling which could slow down melting. Here we use a compilation of on-glacier meteorological observations to assess the extent to which this relationship changes under warming. Statistical modelling of the potential temperature decoupling of the world’s mountain glaciers indicates that currently glacier boundary layers warm ~0.83 °C on average for every degree of ambient temperature rise. Future projections under shared socioeconomic pathway (SSP) climate scenarios SSP 2-4.5 and SSP 5-8.5 indicate that decoupling, and thus relative cooling over glaciers, is maximized during the 2020s and 2030s, before widespread glacier retreat acts to recouple above-glacier air temperatures with its surroundings. This nonlinear feedback will lead to an increased sensitivity to warming from midcentury, with glaciers losing their capacity to affect the local climate and cool themselves.}, author = {Shaw, Thomas and Miles, Evan S. and McCarthy, Michael and Buri, Pascal and Guyennon, Nicolas and Salerno, Franco and Carturan, Luca and Brock, Benjamin and Pellicciotti, Francesca}, issn = {1758-6798}, journal = {Nature Climate Change}, pages = {1212--1218}, publisher = {Springer Nature}, title = {{Mountain glaciers recouple to atmospheric warming over the twenty-first century}}, doi = {10.1038/s41558-025-02449-0}, volume = {15}, year = {2025}, } @article{20546, abstract = {Rocky debris covers around 7.3 % of the global glacier area, influencing ice melt rates and the surface mass balance of glaciers, making the dynamics and hydrology of debris-covered glaciers distinct from those of clean-ice glaciers. Accurate representation of debris in models is challenging, as measurements of the physical properties and thickness of the supraglacial debris layer are scarce. Here, we compile a database of measured and reported bulk physical properties and layer thicknesses of supraglacial debris that we call the supraglacial Debris Database (DebDaB) and that is open to community submissions. The majority of the database (90 %) is compiled from 172 sources in the literature, and the remaining 10 % was previously unpublished. DebDaB contains 8741 data entries for supraglacial debris layer thickness, of which 1770 entries also include sub-debris ablation rates, 179 thermal conductivity of debris, 160 aerodynamic surface roughness length, 79 debris albedo, 59 debris emissivity, and 37 debris porosity. The data are distributed over 84 glaciers in 13 regions in the Global Terrestrial Network for Glaciers. We show regional differences in the distribution of debris thickness measurements in DebDaB and fit simplified Østrem curves to 19 glaciers with sufficient debris thickness and ablation data. The data in DebDaB can be used for energy balance, melt, and surface mass balance studies by incorporating site-specific debris properties or for evaluation of remote sensing estimates of debris thickness and surface roughness. They can also help future field campaigns on debris-covered glaciers by identifying observation gaps. DebDaB's uneven spatial coverage points to sampling biases in community efforts to observe debris-covered glaciers, with some regions (e.g. central Europe and South Asia) well-sampled but others having gaps with prevalent debris (e.g. the Andes and Alaska). Debris thickness measurements are mostly concentrated at lower elevations, leaving higher-elevation debris-covered areas undersampled and suggesting that our knowledge of debris properties might not be representative of all elevations. The aims of DebDaB, as an openly available dataset, are to evolve over time, to be updated, and to add to community submissions as new data on supraglacial properties become available. The data described in this paper can be accessed from Zenodo at https://doi.org/10.5281/zenodo.14224835 (Groeneveld et al., 2025).}, author = {Fontrodona-Bach, Adrià and Groeneveld, Lars and Miles, Evan and McCarthy, Michael and Shaw, Thomas and Melo Velasco, Juan Vicente and Pellicciotti, Francesca}, issn = {1866-3516}, journal = {Earth System Science Data}, number = {8}, pages = {4213--4234}, publisher = {Copernicus Publications}, title = {{DebDaB: A database of supraglacial debris thickness and physical properties}}, doi = {10.5194/essd-17-4213-2025}, volume = {17}, year = {2025}, } @misc{20547, abstract = {DebdaB is a database of measured and reported physical properties and thickness of supraglacial debris that is openly available and open to community submissions. The majority of the database (90%) is compiled from 172 sources in the literature, and the remaining 10% has not been published before. DebDaB contains 8,286 data entries for supraglacial debris thickness, of which 1,852 entries also include sub-debris ablation rates, 167 data entries of thermal conductivity of debris, 157 of aerodynamic surface roughness length, 77 of debris albedo, 56 of debris emissivity and 37 of debris porosity. The data are distributed over 83 glaciers in 13 regions in the Global Terrestrial Network for Glaciers. }, author = {Groeneveld, Lars and Fontrodona-Bach, Adrià and Miles, Evan and McCarthy, Michael and Melo Velasco, Juan Vicente and Shaw, Thomas and Pellicciotti, Francesca and Bauder, Andreas and Buri, Pascal and Kneib, Marin and Kumar, Amit and Mishra, Aditya and Petersen, lene and Renner, Roman and Schmid, Sandro}, publisher = {Zenodo}, title = {{DebDaB: A database of supraglacial debris thickness and physical properties}}, doi = {10.5281/ZENODO.14224835}, year = {2025}, } @article{20703, abstract = {Glacier melt sustains water discharge from mountain basins during droughts, but ongoing glacier retreat threatens this fundamental capacity. Here, we assess the response of glaciers in the Southern Andes to one of the most severe, persistent, and extensive droughts on record in South America (2010-present), and to projected end-of-century megadroughts. Using glacio-hydrological numerical simulations, we show that despite a mean annual precipitation deficit of 36%, glacier runoff in 2010-2019 remained almost unaltered compared to the preceding decade (2000-2009), sustained by a 10% loss of total ice volume. However, simulations of future glacier evolution indicate that annual and summer glacier runoff could decline by up to 20 ± 11% and 48 ± 6%, respectively, during end-of-century megadroughts compared to pre-2010 levels. Our results project a weakening of the glacier’s buffering role against precipitation deficits during extreme droughts, increasing water scarcity for ecosystems and livelihoods in the mountain regions of South America.}, author = {Ayala, Álvaro and Muñoz-Castro, Eduardo and Farinotti, Daniel and Farías-Barahona, David and Mendoza, Pablo A. and Macdonell, Shelley and Mcphee, James and Vargas, Ximena and Pellicciotti, Francesca}, issn = {2662-4435}, journal = {Communications Earth and Environment}, publisher = {Springer Nature}, title = {{Less water from glaciers during future megadroughts in the Southern Andes}}, doi = {10.1038/s43247-025-02845-6}, volume = {6}, year = {2025}, } @article{14885, abstract = {The near-surface boundary layer can mediate the response of mountain glaciers to external climate, cooling the overlying air and promoting a density-driven glacier wind. The fundamental processes are conceptually well understood, though the magnitudes of cooling and presence of glacier winds are poorly quantified in space and time, increasing the forcing uncertainty for melt models. We utilize a new data set of on-glacier meteorological measurements on three neighboring glaciers in the Swiss Alps to explore their distinct response to regional climate under the extreme 2022 summer. We find that synoptic wind origins and local terrain modifications, not only glacier size, play an important role in the ability of a glacier to cool the near-surface air. Warm air intrusions from valley or synoptically-driven winds onto the glacier can occur between ∼19% and 64% of the time and contribute between 3% and 81% of the total sensible heat flux to the surface during warm afternoon hours, depending on the fetch of the glacier flowline and its susceptibility to boundary layer erosion. In the context of extreme summer warmth, indicative of future conditions, the boundary layer cooling (up to 6.5°C cooler than its surroundings) and resultant katabatic wind flow are highly heterogeneous between the study glaciers, highlighting the complex and likely non-linear response of glaciers to an uncertain future.}, author = {Shaw, Thomas and Buri, Pascal and Mccarthy, Michael and Miles, Evan S. and Pellicciotti, Francesca}, issn = {2169-8996}, journal = {Journal of Geophysical Research: Atmospheres}, number = {2}, publisher = {Wiley}, title = {{Local controls on near-surface glacier cooling under warm atmospheric conditions}}, doi = {10.1029/2023JD040214}, volume = {129}, year = {2024}, } @article{14938, abstract = {High elevation headwater catchments are complex hydrological systems that seasonally buffer water and release it in the form of snow and ice melt, modulating downstream runoff regimes and water availability. In High Mountain Asia (HMA), where a wide range of climates from semi-arid to monsoonal exist, the importance of the cryospheric contributions to the water budget varies with the amount and seasonal distribution of precipitation. Losses due to evapotranspiration and sublimation are to date largely unquantified components of the water budget in such catchments, although they can be comparable in magnitude to glacier melt contributions to streamflow. 
Here, we simulate the hydrology of three high elevation headwater catchments in distinct climates in HMA over 10 years using an ecohydrological model geared towards high-mountain areas including snow and glaciers, forced with reanalysis data. 
Our results show that evapotranspiration and sublimation together are most important at the semi-arid site, Kyzylsu, on the northernmost slopes of the Pamir mountain range. Here, the evaporative loss amounts to 28% of the water throughput, which we define as the total water added to, or removed from the water balance within a year. In comparison, evaporative losses are 19% at the Central Himalayan site Langtang and 13% at the wettest site, 24K, on the Southeastern Tibetan Plateau. At the three sites, respectively, sublimation removes 15%, 13% and 6% of snowfall, while evapotranspiration removes the equivalent of 76%, 28% and 19% of rainfall. In absolute terms, and across a comparable elevation range, the highest ET flux is 413 mm yr-1 at 24K, while the highest sublimation flux is 91 mm yr-1 at Kyzylsu. During warm and dry years, glacier melt was found to only partially compensate for the annual supply deficit.}, author = {Fugger, Stefan and Shaw, Thomas and Jouberton, Achille and Miles, Evan and Buri, Pascal and McCarthy, Michael and Fyffe, Catriona Louise and Fatichi, Simone and Kneib, Marin and Molnar, Peter and Pellicciotti, Francesca}, issn = {1748-9326}, journal = {Environmental Research Letters}, keywords = {Public Health, Environmental and Occupational Health, General Environmental Science, Renewable Energy, Sustainability and the Environment}, publisher = {IOP Publishing}, title = {{Hydrological regimes and evaporative flux partitioning at the climatic ends of High Mountain Asia}}, doi = {10.1088/1748-9326/ad25a0}, volume = {19}, year = {2024}, } @article{15298, abstract = {Mountains are important suppliers of freshwater to downstream areas, affecting large populations in particular in High Mountain Asia (HMA). Yet, the propagation of water from HMA headwaters to downstream areas is not fully understood, as interactions in the mountain water cycle between the cryo-, hydro- and biosphere remain elusive. We review the definition of blue and green water fluxes as liquid water that contributes to runoff at the outlet of the selected domain (blue) and water lost to the atmosphere through vapor fluxes, that is evaporation from water, ground, and interception plus transpiration (green) and propose to add the term white water to account for the (often neglected) evaporation and sublimation from snow and ice. We provide an assessment of models that can simulate the cryo-hydro-biosphere continuum and the interactions between spheres in high mountain catchments, going beyond disciplinary separations. Land surface models are uniquely able to account for such complexity, since they solve the coupled fluxes of water, energy, and carbon between the land surface and atmosphere. Due to the mechanistic nature of such models, specific variables can be compared systematically to independent remote sensing observations – providing vital insights into model accuracy and enabling the understanding of the complex watersheds of HMA. We discuss recent developments in spaceborne earth observation products that have the potential to support catchment modeling in high mountain regions. We then present a pilot study application of the mechanistic land surface model Tethys & Chloris to a glacierized watershed in the Nepalese Himalayas and discuss the use of high-resolution earth observation data to constrain the meteorological forcing uncertainty and validate model results. We use these insights to highlight the remaining challenges and future opportunities that remote sensing data presents for land surface modeling in HMA.}, author = {Buri, Pascal and Fatichi, Simone and Shaw, Thomas and Fyffe, Catriona Louise and Miles, Evan S. and Mccarthy, Michael and Kneib, Marin and Ren, Shaoting and Jouberton, Achille and Fugger, Stefan and Jia, Li and Zhang, Jing and Shen, Cong and Zheng, Chaolei and Menenti, Massimo and Pellicciotti, Francesca}, issn = {1009-5020}, journal = {Geo-Spatial Information Science}, number = {3}, pages = {703--727}, publisher = {Taylor & Francis}, title = {{Land surface modeling informed by earth observation data: Toward understanding blue–green–white water fluxes in High Mountain Asia}}, doi = {10.1080/10095020.2024.2330546}, volume = {27}, year = {2024}, } @article{14487, abstract = {High Mountain Asia (HMA) is among the most vulnerable water towers globally and yet future projections of water availability in and from its high-mountain catchments remain uncertain, as their hydrologic response to ongoing environmental changes is complex. Mechanistic modeling approaches incorporating cryospheric, hydrological, and vegetation processes in high spatial, temporal, and physical detail have never been applied for high-elevation catchments of HMA. We use a land surface model at high spatial and temporal resolution (100 m and hourly) to simulate the coupled dynamics of energy, water, and vegetation for the 350 km2 Langtang catchment (Nepal). We compare our model outputs for one hydrological year against a large set of observations to gain insight into the partitioning of the water balance at the subseasonal scale and across elevation bands. During the simulated hydrological year, we find that evapotranspiration is a key component of the total water balance, as it causes about the equivalent of 20% of all the available precipitation or 154% of the water production from glacier melt in the basin to return directly to the atmosphere. The depletion of the cryospheric water budget is dominated by snow melt, but at high elevations is primarily dictated by snow and ice sublimation. Snow sublimation is the dominant vapor flux (49%) at the catchment scale, accounting for the equivalent of 11% of snowfall, 17% of snowmelt, and 75% of ice melt, respectively. We conclude that simulations should consider sublimation and other evaporative fluxes explicitly, as otherwise water balance estimates can be ill-quantified.}, author = {Buri, Pascal and Fatichi, Simone and Shaw, Thomas and Miles, Evan S. and Mccarthy, Michael and Fyffe, Catriona Louise and Fugger, Stefan and Ren, Shaoting and Kneib, Marin and Jouberton, Achille and Steiner, Jakob and Fujita, Koji and Pellicciotti, Francesca}, issn = {1944-7973}, journal = {Water Resources Research}, number = {10}, publisher = {Wiley}, title = {{Land surface modeling in the Himalayas: On the importance of evaporative fluxes for the water balance of a high-elevation catchment}}, doi = {10.1029/2022WR033841}, volume = {59}, year = {2023}, } @misc{14494, abstract = {We provide i) gridded initial conditions (.tif), ii) modeled gridded monthly outputs (.tif), and iii) modeled hourly outputs at the station locations (.txt) for the hydrological year 2019. Information about the variables and units can be found in the figures (.png) associated to each dataset. Details about the datasets can be found in the original publication by Buri and others (2023). Buri, P., Fatichi, S., Shaw, T. E., Miles, E. S., McCarthy, M. J., Fyffe, C. L., ... & Pellicciotti, F. (2023). Land Surface Modeling in the Himalayas: On the Importance of Evaporative Fluxes for the Water Balance of a High‐Elevation Catchment. Water Resources Research, 59(10), e2022WR033841. DOI: 10.1029/2022WR033841}, author = {Buri, Pascal and Fatichi, Simone and Shaw, Thomas and Miles, Evan and McCarthy, Michael and Fyffe, Catriona Louise and Fugger, Stefan and Ren, Shaoting and Kneib, Marin and Jouberton, Achille and Steiner, Jakob and Fujita, Koji and Pellicciotti, Francesca}, publisher = {Zenodo}, title = {{Model output data to "Land surface modeling in the Himalayas: on the importance of evaporative fluxes for the water balance of a high elevation catchment"}}, doi = {10.5281/ZENODO.8402426}, year = {2023}, } @article{14659, abstract = {Understanding the response of Himalayan glaciers to global warming is vital because of their role as a water source for the Asian subcontinent. However, great uncertainties still exist on the climate drivers of past and present glacier changes across scales. Here, we analyse continuous hourly climate station data from a glacierized elevation (Pyramid station, Mount Everest) since 1994 together with other ground observations and climate reanalysis. We show that a decrease in maximum air temperature and precipitation occurred during the last three decades at Pyramid in response to global warming. Reanalysis data suggest a broader occurrence of this effect in the glacierized areas of the Himalaya. We hypothesize that the counterintuitive cooling is caused by enhanced sensible heat exchange and the associated increase in glacier katabatic wind, which draws cool air downward from higher elevations. The stronger katabatic winds have also lowered the elevation of local wind convergence, thereby diminishing precipitation in glacial areas and negatively affecting glacier mass balance. This local cooling may have partially preserved glaciers from melting and could help protect the periglacial environment.}, author = {Salerno, Franco and Guyennon, Nicolas and Yang, Kun and Shaw, Thomas and Lin, Changgui and Colombo, Nicola and Romano, Emanuele and Gruber, Stephan and Bolch, Tobias and Alessandri, Andrea and Cristofanelli, Paolo and Putero, Davide and Diolaiuti, Guglielmina and Tartari, Gianni and Verza, Gianpietro and Thakuri, Sudeep and Balsamo, Gianpaolo and Miles, Evan S. and Pellicciotti, Francesca}, issn = {1752-0908}, journal = {Nature Geoscience}, pages = {1120--1127}, publisher = {Springer Nature}, title = {{Local cooling and drying induced by Himalayan glaciers under global warming}}, doi = {10.1038/s41561-023-01331-y}, volume = {16}, year = {2023}, } @article{14779, abstract = {The presence of a developed boundary layer decouples a glacier's response from ambient conditions, suggesting that sensitivity to climate change is increased by glacier retreat. To test this hypothesis, we explore six years of distributed meteorological data on a small Swiss glacier in the period 2001–2022. Large glacier fragmentation has occurred since 2001 (−35% area change up to 2022) coinciding with notable frontal retreat, an observed switch from down‐glacier katabatic to up‐glacier valley winds and an increased sensitivity (ratio) of on‐glacier to off‐glacier temperature. As the glacier ceases to develop density‐driven katabatic winds, sensible heat fluxes on the glacier are increasingly determined by the conditions occurring outside the boundary layer of the glacier, sealing the glacier's demise as the climate continues to warm and experience an increased frequency of extreme summers.}, author = {Shaw, Thomas E. and Buri, Pascal and McCarthy, Michael and Miles, Evan S. and Ayala, Álvaro and Pellicciotti, Francesca}, issn = {1944-8007}, journal = {Geophysical Research Letters}, keywords = {General Earth and Planetary Sciences, Geophysics}, number = {11}, publisher = {American Geophysical Union}, title = {{The decaying near‐surface boundary layer of a retreating alpine glacier}}, doi = {10.1029/2023gl103043}, volume = {50}, year = {2023}, } @misc{14919, abstract = {GLACIER METEOROLOGICAL DATA SWISS ALPS -2022 }, author = {Shaw, Thomas and Buri, Pascal and McCarthy, Michael and Miles, Evan and Pellicciotti, Francesca}, publisher = {Zenodo}, title = {{Air temperature and near-surface meteorology datasets on three Swiss glaciers - Extreme 2022 Summer}}, doi = {10.5281/ZENODO.8277285}, year = {2023}, } @article{12573, abstract = {Supraglacial debris strongly modulates glacier melt rates and can be decisive for ice dynamics and mountain hydrology. It is ubiquitous in High-Mountain Asia, yet because its thickness and supply rate from local topography are poorly known, our ability to forecast regional glacier change and streamflow is limited. Here we combined remote sensing and numerical modelling to resolve supraglacial debris thickness by altitude for 4689 glaciers in High-Mountain Asia, and debris-supply rate to 4141 of those glaciers. Our results reveal extensively thin supraglacial debris and high spatial variability in both debris thickness and supply rate. Debris-supply rate increases with the temperature and slope of debris-supply slopes regionally, and debris thickness increases as ice flow decreases locally. Our centennial-scale estimates of debris-supply rate are typically an order of magnitude or more lower than millennial-scale estimates of headwall-erosion rate from Beryllium-10 cosmogenic nuclides, potentially reflecting episodic debris supply to the region’s glaciers.}, author = {McCarthy, Michael and Miles, Evan and Kneib, Marin and Buri, Pascal and Fugger, Stefan and Pellicciotti, Francesca}, issn = {2662-4435}, journal = {Communications Earth & Environment}, keywords = {General Earth and Planetary Sciences, General Environmental Science}, publisher = {Springer Nature}, title = {{Supraglacial debris thickness and supply rate in High-Mountain Asia}}, doi = {10.1038/s43247-022-00588-2}, volume = {3}, year = {2022}, }