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Mountain Cryosphere Subgrid Parameterization and Computation (CRYOSUB)

English title Mountain Cryosphere Subgrid Parameterization and Computation (CRYOSUB)
Applicant Gruber Stephan
Number 121868
Funding scheme Project funding (Div. I-III)
Research institution Geographisches Institut Universität Zürich
Institution of higher education University of Zurich - ZH
Main discipline Hydrology, Limnology, Glaciology
Start/End 01.05.2009 - 30.04.2012
Approved amount 163'356.00
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All Disciplines (3)

Hydrology, Limnology, Glaciology
Climatology. Atmospherical Chemistry, Aeronomy

Keywords (10)

mountain cryosphere; impact of climate change; sub-grid effects; permafrost; snow; glaciers; Mountains; cryosphere; scale; modelling

Lay Summary (English)

Lay summary
In mountain areas, most things vary strongly over short distance - examples of this are: elevation, ground material and the amount of sunshine. Similarly, the mountain cryosphere (snow, glaciers, permafrost) is subject to strong variability: A southern slope may have blossoming flowers, while at 20m distance a northern slope is snow-covered, or, horizontal ground at 2600m elevation can have a grass cover while less than 1 km away, horizontal ground at 3600m is glacier covered. This variability is remarkable, because similar gradients in flat terrain would stretch over distances of many hundreds or thousands of km. Techniques for estimating conditions at the land surface often use computer models that represent the physics of important processes. Here, simulating land surface conditions in mountains requires a fine spatial resolution to capture the strong lateral variability. The fine resolution, however, comes at a price: it requires a lot of computer resources and limits such model simulations to small areas, only. In CRYOSUB, we will evaluate a technique to represent the most important part of the variability of land surface in mountain areas with a strongly reduced amount of computations. Distributed models calculate points at a regular spacing (e.g., every 25m). In this project we will use a so-called lumped model that exploits similarity between places that are alike. This means that only few points with certain characteristics are computed and all other points in between will be interpolated. As an example: steep south-facing rock at 2700m is likely to behave in a predictable way based on simulations for 2500m and 3000m south facing situations. Also a lumped model can have different resolutions - in the previous example, one could e.g., additionally calculate at 2750m.This approach may save a factor of 1,000-100,000 of computing resources compared to distributed models. This opens the possibility to quantify and investigate phenomena in mountains using resources for different purposes: covering a larger area, having results quicker, or quantifying uncertainty. This new method will have a benefit (saved computations) and a cost (lost quality of the simulation). We will use one high-resolution distributed model results and measurements as a baseline and compare the cost and benefit of diverse model resolutions, both with the new lumped and the distributed method. This method has the potential to improve our ability to quantify the impact of climate change in mountain areas and help answer questions such as: Where is permafrost? Where will it thaw the fastest? How will the snow cover on south slopes change in the coming decades?
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants



Derivation and analysis of a high-resolution estimate of global permafrost zonation
Gruber S. (2012), Derivation and analysis of a high-resolution estimate of global permafrost zonation, in The Cryosphere, 6(1), 221-233.
Inferring snow pack ripening and melt out from distributed ground surface temperature measurements
Schmid M.-O., Gubler S., Fiddes J., Gruber S. (2012), Inferring snow pack ripening and melt out from distributed ground surface temperature measurements, in The Cryosphere Discussions, 6(1), 563-591.
TopoSUB: a tool for efficient large area numerical modelling in complex topography at sub-grid scales
Fiddes J., Gruber S. (2012), TopoSUB: a tool for efficient large area numerical modelling in complex topography at sub-grid scales, in Geoscientific Model Development Discussions, 5(2), 1041-1076.
Scale-dependent measurement and analysis of ground surface temperature variability in alpine terrain
Gubler S., Fiddes J., Keller M., Gruber S. (2011), Scale-dependent measurement and analysis of ground surface temperature variability in alpine terrain, in The Cryosphere, 5(2), 431-443.

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Third European Conference on Permafrost 13.06.2010 Longyearbyen, Svalbard, Norway

Associated projects

Number Title Start Funding scheme
63678 Analysis and Spatial Modelling of Permafrost Distribution in Cold-Mountain Areas by Integration of Advanced Remote Sensing technology. 01.04.2001 Project funding (Div. I-III)
136279 The evolution of mountain permafrost in Switzerland 01.11.2011 Sinergia
67322 NCCR MICS: Mobile Information and Communication Systems (phase I) 01.11.2001 National Centres of Competence in Research (NCCRs)
107963 Frozen rock walls and climate change: transient 3-dimensional investigation of permafrost degradation 01.04.2005 Project funding (Div. I-III)
178628 The 2°C target in the Alps - An Experience in Virtual Reality 01.05.2018 Agora
140422 Extension of Mountain Cryosphere Subgrid Parameterization and Computation (CRYOSUB-E) 01.05.2012 Project funding (Div. I-III)


The expected outcome of this project is a method that allows for continental-scale modeling of permafrost, snow and glacier mass balance in mountain areas under present and simulated future climate. This is important because the mountain cryosphere influences a large proportion of the global land mass and population, experiences high rates of climate change and is currently inadequately resolved in regional climate models do to the dominating influence of sub-grid variability. This project does not address climate modelling but will rather provide a proof of concept for the inclusion of topography sub-grid schemes into climate models where it has the potential to improve the modeling of radiative and moisture fluxes over mountain topography. Mountain areas are characterized by an extreme lateral variability in elevation, ground material and exposure to solar radiation. This can cause differences in e.g. mean annual ground temperature or snow cover duration over distances on tens to hundreds of meters that are equivalent to hundreds of kilometers or more in flat terrain. We propose a mechanism to effectively represent the most important aspect of this sub-grid variability in a way that is suitable to be used on a continental scale, driven by re-analysis or regional climate model data. A usual RCM cell has dimensions in the order of tens of kilometers and provides one value for ground conditions on that scale. The new scheme we propose will use high-resolution digital elevation models to segment the landscape into classes along the main axes of variability, parameterize the topographic effect on surface fluxes and compute the land surface scheme for each class. In this way, differentiated interpretations can be made based on the results e.g. “Permafrost in low-elevation valley bottoms” and the results can be regionalized to the original high-resolution of the digital elevation model. The research proposed here focuses on a one-way coupling, i.e. a scheme in which results from regional models are used but the results of the surface calculation do not feed back into the original model. This allows a thorough and realistic development and evaluation of the method with measured as well as simulated climate data as well as first applications worldwide. At the same time it provides a proof of concept for a later “two-way” or “online” coupling where this approach could be included in regional climate models. Close collaboration with climate scientists, mountain hydrologists amd high-latitude cryosphere researchers is already now included in the proposed project.