RAVEN has resulted in a number of fundamental advances beyond the current state of the art and several groundbreaking insights in High Mountain Asia, in particular regarding the stage of development of supraglacial debris cover in the region, as well as an unprecedented examination of the current health and long-term sustainability of the region’s glaciers.
Our development of a new, transferable method for automated mapping of ice cliffs on debris-covered glaciers opens the door to systematic, robust mapping of both ice cliffs and supraglacial ponds across High Mountain Asia. We have completed analyses of seasonal and interannual ice cliff and supraglacial pond dynamics at four study glaciers and a large-scale assessment (86 glaciers across HMA) of supraglacial ice cliff and pond extent and their topographic and glaciological controls.
We generated a global assessment of glacier debris cover stage of development, which developed a very novel understanding of the stage of evolution of supraglacial debris over all glaciers worldwide. It demonstrated that debris-covered glaciers in High Mountain Asia are at an advanced state of decay, and allowed understanding the conditions over which ice cliffs and ponds can form and develop, thereby giving an unprecedented understanding of the surface topography and melt patterns of debris-covered glaciers and their evolution.
We developed and performed a new systematic analysis of glacier surface mass balance across High Mountain Asia in the first large-scale application of the continuity equation, revealing the poor glacier health in the region in unprecedented detail. Large-scale results stemming from this major advance include an analysis of supraglacial debris thickness and implied debris supply rates across High Mountain Asia and an examination of the importance of sub-debris melt into rivers across High Mountain Asia.
We quantified the melt contribution of ice cliffs and supraglacial ponds at the catchment scale. We completed a global comparison of the energy balance of ice cliffs, supraglacial ponds, and debris-covered ice, extending understanding of associated melt rates beyond High Mountain Asia. A new stochastic population dynamics model of ice cliff and supraglacial pond variations was used for the first time to disentangle these features’ internal dynamics from the influence of external drivers (glacier dynamics and climatic conditions). New datasets collected from time-lapse camera arrays have provided insight into the subseasonal processes and dynamics of ice cliffs, supraglacial hydrology, and debris mobilization rates. We developed time-lapse photogrammetry techniques to derive the evolution of individual cliffs at the weekly scale, and to validate our model. These individual advances were drawn together into a conceptual model of the surface characteristics of debris-covered glaciers at their different stages of evolution.
We led the first debris-covered glacier melt model intercomparison. We performed the first multi-site investigation of the relative influence of the monsoon, debris thickness, and elevation on the energy balance of debris-covered and clean ice glaciers in HMA. We advanced a hyper-resolution land surface model that represents the mountain cryosphere, hydrosphere and biosphere in a much more advanced and substantially distinct manner from traditional glacio-hydrological models. We have quantified the importance of debris-covered glaciers for catchment water balance at the four study sites and provided a first analysis of blue-green water interactions in high-mountain Asian catchments.
We have produced novel long term projections of glacier and streamflow change at four catchments in High Mountain Asia that for the first time: i) describe all components of the cryosphere and hydrosphere using physics-based equations, and do not reply on empirical simplifications; ii) in particular, include the key role of debris in modulating glacier response at short and long time scales, with the potential of importantly altering the trajectory of cryospheric response; and iii) describe the complex interrelationship between cryosphere, hydrosphere and biosphere, and allow for feedback between processes to modulate the catchment response to a warming climate. Using the hyper-resolution land surface model, we have quantified the importance of debris, ice cliffs and supraglacial ponds to future glacier mass balance and change across High Mountain Asia, as well as the changing roles of vegetation phenology and glacier seasonal melt in controlling high-mountain catchment water budgets.
