Impact of two conceptual precipitation downscaling schemes on mass-balance modeling of Gran Campo Nevado ice cap, Patagonia

Weidemann, Stephanie Suzanne; Sauter, Tobias; Schneider, Lars; Schneider, Christoph

doi:10.3189/2013jog13j046

Cited by 22 publications

(30 citation statements)

References 51 publications

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“…All these studies use the MB as the predicted variable and do not use the terminology of "downscaling", that is extensively used in climate research. Statistical downscaling studies that target glaciological applications often focus on one or more meteorological variables at the glacier surface (Hofer et al, 2010(Hofer et al, , 2012 for use in a subsequent MB model for example (Jarosch et al, 2010;Weidemann et al, 2013).…”

Section: F Maussion Et Al: Enso Influence On Shallap Glacier Cordimentioning

confidence: 99%

ENSO influence on surface energy and mass balance at Shallap Glacier, Cordillera Blanca, Peru

et al. 2015

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Abstract. The El Niño/Southern Oscillation (ENSO) is a major driver of climate variability in the tropical Andes, where recent Niño and Niña events left an observable footprint on glacier mass balance. The nature and strength of the relationship between ENSO and glacier mass balance, however, varies between regions and time periods, leaving several unanswered questions about its exact mechanisms. The starting point of this study is a 4-year long time series of distributed surface energy and mass balance (SEB/SMB) calculated using a process-based model driven by observations at Shallap Glacier (Cordillera Blanca, Peru). These data are used to calibrate a regression-based downscaling model that links the local SEB/SMB fluxes to atmospheric reanalysis variables on a monthly basis, allowing an unprecedented quantification of the ENSO influence on the SEB/SMB at climatological time scales (1980-2013. We find a stronger and steadier anti-correlation between Pacific sea-surface temperature (SST) and glacier mass balance than previously reported. This relationship is most pronounced during the wet season (December-May) and at low altitudes where Niño (Niña) events are accompanied with a snowfall deficit (excess) and a higher (lower) radiation energy input. We detect a weaker but significant ENSO anticorrelation with total precipitation (Niño dry signal) and positive correlation with the sensible heat flux, but find no ENSO influence on sublimation. Sensitivity analyses comparing several downscaling methods and reanalysis data sets resulted in stable mass balance correlations with Pacific SST but also revealed large uncertainties in computing the mass balance trend of the last decades. The newly introduced open-source downscaling tool can be applied easily to other glaciers in the tropics, opening new research possibilities on even longer time scales.

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Section: F Maussion Et Al: Enso Influence On Shallap Glacier Cordimentioning

confidence: 99%

ENSO influence on surface energy and mass balance at Shallap Glacier, Cordillera Blanca, Peru

et al. 2015

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“…This constraint makes it challenging to infer on micrometeorological conditions from a limited number of observations. Glaciological modeling studies typically circumvent this obstacle by constructing meteorological forcing fields, e.g., for temperature and wind, from scattered observations using fixed or variable lapse rates (e.g., Greuell and Böhm, 1998;Carturan et al, 2015;Ayala et al, 2015;Petersen et al, 2013;Huintjes et al, 2015;Weidemann et al, 2013;Jarosch et al, 2012). The interpolated fields then serve for the estimation of turbulent fluxes at any given point on the glacier.…”

Section: T Sauter and S P Galos: Effects Of Local Advection On Thementioning

confidence: 99%

“…10). The simulated (LES) wind velocities and temperatures at the two sites are linearly extrapolated across the glacier to obtain a temperature field (e.g., Paul and Kotlarski, 2010;Machguth et al, 2009;Huintjes et al, 2015;Weidemann et al, 2013;Jarosch et al, 2012). For comparison, we also estimate a second temperature field using a simple thermodynamic glacier wind model that accounts for air temperature variations along the flow line.…”

Section: Reliability Of the Les Experimentsmentioning

confidence: 99%

Effects of local advection on the spatial sensible heat flux variation on a mountain glacier

Sauter

Galos

2016

The Cryosphere

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Abstract. Distributed mass balance models, which translate micrometeorological conditions into local melt rates, have proven deficient to reflect the energy flux variability on mountain glaciers. This deficiency is predominantly related to shortcomings in the representation of local processes in the forcing data. We found by means of idealized large-eddy simulations that heat advection, associated with local wind systems, causes small-scale sensible heat flux variations by up to 100 W m −2 during clear sky conditions. Here we show that process understanding at a few observation sites is insufficient to infer the wind and temperature distributions across the glacier. The glacier-wide hourly averaged sensible heat fluxes are both over-and underestimated by up to 16 W m −2 when using extrapolated temperature and wind fields. The sign and magnitude of the differences depend on the site selection, which is used for extrapolation as well as on the large-scale flow direction. Our results demonstrate how the shortcomings in the local sensible heat flux estimates are related to topographic effects and the insufficient characterization of the temperature advection process.

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“…While the LT model includes many assumptions and is not able to represent nonlinear processes, it is highly adaptable and has been explored and applied in numerous mountainous regions (e.g., Barstad and Smith, 2005;Anders et al, 2007Anders et al, , 2008Minder, 2010). However, it has only been used for direct glaciological applications in Iceland Jóhannesson et al, 2007), Norway (Schuler et al, 2008), Western Canada (Jarosch et al, 2012), and Patagonia (Weidemann et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Modeling Winter Precipitation Over the Juneau Icefield, Alaska, Using a Linear Model of Orographic Precipitation

et al. 2018

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Assessing and modeling precipitation in mountainous areas remains a major challenge in glacier mass balance modeling. Observations are typically scarce and reanalysis data and similar climate products are too coarse to accurately capture orographic effects. Here we use the linear theory of orographic precipitation model (LT model) to downscale winter precipitation from the Weather Research and Forecasting Model (WRF) over the Juneau Icefield, one of the largest ice masses in North America (>4,000 km 2 ), for the period 1979-2013. The LT model is physically-based yet computationally efficient, combining airflow dynamics and simple cloud microphysics. The resulting 1 km resolution precipitation fields show substantially reduced precipitation on the northeastern portion of the icefield compared to the southwestern side, a pattern that is not well captured in the coarse resolution (20 km) WRF data. Net snow accumulation derived from the LT model precipitation agrees well with point observations across the icefield. To investigate the robustness of the LT model results, we perform a series of sensitivity experiments varying hydrometeor fall speeds, the horizontal resolution of the underlying grid, and the source of the meteorological forcing data. The resulting normalized spatial precipitation pattern is similar for all sensitivity experiments, but local precipitation amounts vary strongly, with greatest sensitivity to variations in snow fall speed. Results indicate that the LT model has great potential to provide improved spatial patterns of winter precipitation for glacier mass balance modeling purposes in complex terrain, but ground observations are necessary to constrain model parameters to match total amounts.

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Impact of two conceptual precipitation downscaling schemes on mass-balance modeling of Gran Campo Nevado ice cap, Patagonia

Cited by 22 publications

References 51 publications

ENSO influence on surface energy and mass balance at Shallap Glacier, Cordillera Blanca, Peru

ENSO influence on surface energy and mass balance at Shallap Glacier, Cordillera Blanca, Peru

Effects of local advection on the spatial sensible heat flux variation on a mountain glacier

Modeling Winter Precipitation Over the Juneau Icefield, Alaska, Using a Linear Model of Orographic Precipitation

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