Effects of stratified active layers on high-altitude permafrost warming:
a case study on the Qinghai–Tibet Plateau

Abstract. Simulations of land-surface processes and phenomena often require driving time series of meteorological variables. Corresponding observations, however, are unavailable in most locations, even more so, when considering the duration, continuity and data quality required. Atmospheric reanalyses provide global coverage of relevant meteorological variables, but their use is largely restricted to grid-based studies. This is because technical challenges limit the ease with which reanalysis data can be applied to models at the site scale. We present the software toolkit GlobSim, which automates the downloading, interpolation and scaling of different reanalyses – currently ERA5, ERA-Interim, JRA-55 and MERRA-2 – to produce meteorological time series for user-defined point locations. The resulting data have consistent structure and units to efficiently support ensemble simulation. The utility of GlobSim is demonstrated using an application in permafrost research. We perform ensemble simulations of ground-surface temperature for 10 terrain types in a remote tundra area in northern Canada and compare the results with observations. Simulation results reproduced seasonal cycles and variation between terrain types well, demonstrating that GlobSim can support efficient land-surface simulations. Ensemble means often yielded better accuracy than individual simulations and ensemble ranges additionally provide indications of uncertainty arising from uncertain input. By improving the usability of reanalyses for research requiring time series of climate variables for point locations, GlobSim can enable a wide range of simulation studies and model evaluations that previously were impeded by technical hurdles in obtaining suitable data.

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“…6). Snow blowing is parameterized as wind compaction in 1-D (Pomeroy et al, 1993) for all the terrain types except the tall shrub site.…”

Section: Model Settings and Parametersmentioning

confidence: 99%

GlobSim (v1.0): deriving meteorological time series for point locations from multiple global reanalyses

et al. 2019

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“…Nitzbon et al (2019) recently extended the thermal-only simulator Cryogrid 3 (Westermann et al, 2016) to include a simplified hydrology scheme that avoids solving the computationally demanding Richards equation. All of these models remove the requirement for imposing surface conditions and as such offer the potential for advancing understanding of permafrost thermal hydrology as an integrated surface/subsurface system (Harp et al, 2015;Atchley et al, 2016;Pan et al, 2016;Sjöberg et al, 2016;Jafarov et al, 2018;Abolt et al, 2018;Nitzbon et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Evaluating integrated surface/subsurface permafrost thermal hydrology models in ATS (v0.88) against observations from a polygonal tundra site

Jan¹,

Coon²,

Painter³

2019

Preprint

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Abstract. Numerical simulations are essential tools for understanding the complex hydrologic response of Arctic regions to a warming climate. However, strong coupling among thermal and hydrological processes on the surface and in the subsurface and the significant role that subtle variations in surface topography have in regulating flow direction and surface storage lead to significant uncertainties. Careful model evaluation against field observations is thus important to build confidence. We evaluate the integrated surface/subsurface permafrost thermal hydrology models in the Advanced Terrestrial Simulator (ATS) against field observations from polygonal tundra at the Barrow Environmental Observatory. ATS couples a multiphase, three-dimensional representation of subsurface thermal hydrology with representations of overland nonisothermal flows, snow processes, and surface energy balance. We simulated thermal hydrology of three-dimensional ice-wedge polygons with generic but broadly representative surface microtopography. The simulations were forced by meteorological data and observed water table elevations in ice-wedge polygon troughs. With limited calibration of parameters appearing in the soil evaporation model, the three-year simulations agreed reasonably well with snow depth, summer water table elevations in the polygon center, and high-frequency soil temperature measurements at several depths in the trough, rim, and center of the polygon. Upscaled evaporation is in good agreement with flux tower observations. The simulations were found to be sensitive to parameters in the bare soil evaporation model, snowpack, and the lateral saturated hydraulic conductivity. The study provides new support for an emerging class of integrated surface/subsurface permafrost simulators, and provides an optimized set of model parameters for use in watershed-scale projections of permafrost dynamics in a warming climate.

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“…GEOtop (version 2.0), a physically-based numerical model, is used for this demonstrator application because it describes the complex abiotic processes in permafrost environments well (e.g. Endrizzi and Marsh, 2010;Gubler et al, 2013;Endrizzi et al, 2014;Pan et al, 2016). It represents the heat and water transfer in soil as well as the energy transfer between the soil and the atmosphere.…”

Section: Process-based Numerical Modelmentioning

confidence: 99%

GlobSim (v1.0): Deriving meteorological time series for point locations from multiple global reanalyses

Cao¹,

Quan²,

Brown³

et al. 2019

Preprint

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Abstract. Simulations of land-surface processes and phenomena often require driving time series of meteorological variables. Corresponding observations, however, are unavailable in most locations, even more so, when considering the duration, continuity and data quality required. Atmospheric reanalyses provide global coverage of relevant meteorological variables, but their use is largely restricted to grid-based studies. This is because technical challenges limit the ease with which reanalysis data can be applied to models at the site scale. We present the software toolkit GlobSim, which automates the downloading, interpolation and scaling of different reanalyses – currently ERA-5, ERA-Interim, JRA-55 and MERRA-2 – to produce meteorological time series for user-defined point locations. The resulting data have consistent structure and units to efficiently support ensemble simulation. The utility of GlobSim is demonstrated using an application in permafrost research. We perform ensemble simulations of ground-surface temperature for ten terrain types in a remote tundra area in northern Canada and compare the results with observations. Simulation results reproduced seasonal cycles and variation between terrain types well, demonstrating that GlobSim can support efficient land-surface simulations. Ensemble means often yielded better accuracy than individual simulation and ensemble ranges additionally provide indications of uncertainty arising from uncertain input. By improving the usability of reanalyses for research requiring time-series of climate variables for point locations, GlobSim can enable a wide range of simulation studies and model evaluations that previously were impeded by technical hurdles in obtaining suitable data.

show abstract

Effects of stratified active layers on high-altitude permafrost warming: a case study on the Qinghai–Tibet Plateau

Cited by 24 publications

References 35 publications

GlobSim (v1.0): deriving meteorological time series for point locations from multiple global reanalyses

GlobSim (v1.0): deriving meteorological time series for point locations from multiple global reanalyses

Evaluating integrated surface/subsurface permafrost thermal hydrology models in ATS (v0.88) against observations from a polygonal tundra site

GlobSim (v1.0): Deriving meteorological time series for point locations from multiple global reanalyses

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