Martin Scherler ¹, Christian Hauck ¹, Nadine Salzmann ¹
Transcription
Martin Scherler ¹, Christian Hauck ¹, Nadine Salzmann ¹
ribourg Projection of permafrost and snow cover evolution under climate change scenarios GEOSCIENCES ALPINE CRYOSPHERE GEOMORPHOLOGY AND Martin Scherler ¹, Christian Hauck ¹, Nadine Salzmann ¹ ¹ Alpine Cryosphere and Geomorphology (ACAG), Department of Geosciences, University of Fribourg, Fribourg, Switzerland ([email protected]) HC 2001 2011 2021 2031 2041 2051 2061 2071 2081 2091 10 15 -100 humidity % -50 0 50 100 -15 wind speed m/s smhi mpi metno hc eth dmi JJA MAM METNO -15 DMI -20 0 MPI depth [m] -10 -15 ETH -20 0 JJA SMHI 2001 2011 2021 2031 2041 2051 2061 2071 2081 2091 Figure 2: Thaw layer depth projections according to 6 different RCM runs for the period from 1991 to 2050/2098 for Schilthorn (left) and Murtèl Corvatsch (right). -15 -20 HC 2001 2011 2021 2031 2041 2051 2061 2071 2081 2091 10 15 -100 MAM smhi mpi metno hc eth dmi MAM SON SON SON SON 0 20 40 -6 incoming shortwave radiation W/m² MAM -2 0 2 4 -40 6 -20 0 20 40 smhi mpi metno hc eth dmi JJA MAM smhi mpi metno hc eth dmi JJA MAM DJF SON SON SON SON 100 -10 -5 0 5 10 -100 -50 0 50 0 2 4 6 smhi mpi metno hc eth dmi MAM DJF 50 -2 JJA DJF 0 -4 precipitation mm DJF -50 100 smhi mpi metno hc eth dmi -6 incoming shortwave radiation W/m² precipitation mm smhi mpi metno hc eth dmi JJA -4 50 MAM DJF -20 0 JJA DJF -40 -50 wind speed m/s JJA 100 -10 -5 0 5 Conclusions 10 Although the predicted increase in air temperature and the decrease in snow cover duration are of the same magnitude for both sites, permafrost conditions at Murtèl are more stable. This is most probably due to the massive ice core in the rock glacier which absorbs a large amount of energy during melting. smhi: 1700.0 m a.s.l.; mpi: 1898.8 m a.s.l.; metno: 2227.4 m a.s.l.; hc: 425.0 m a.s.l.; eth: 1214.5 m a.s.l.; dmi: 1214.1 m a.s.l. measured: 2700 m a.s.l. DMI -5 -10 -15 METNO A J J J J M M A A M M F F J J D D N N O O S S 2010 2020 2030 -10 MPI 2040 2050 2060 2070 2080 2090 ETH A -5 -15 A 2000 -15 -20 J J J M M A A M M F F J J D D N N O O 2000 2010 2020 2030 2040 2050 2060 2070 2080 2000 2090 2010 2020 2030 2040 2050 2060 2070 2080 2090 S M M M M A A A A M M M M F F F F J J J J D D D D N N N N O O O O S S S 2060 2070 2080 2090 HC M F J D N O S 2010 2020 2030 2040 2050 2010 2020 2030 2060 2070 2080 2090 2040 2050 2060 2070 2080 2090 SMHI A A 2000 2000 2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 J J J J M M M A A A M M M F F F J J J D D D N N N O O O S S 2020 2030 2040 2050 2060 2070 2080 2090 2070 2080 2090 2000 2010 2020 2030 2040 2050 3 2.5 2 1.5 1 0.5 2000 2010 2020 2030 2040 2050 2060 2070 2080 350 300 250 200 150 100 50 0 Murtèl 350 300 250 200 DMI ETH HC METNO MPI SMHI average linear 150 100 50 0 2090 A J 2010 2060 Schilthorn 400 SMHI HC A S J 2000 2050 3.5 J 2050 2040 4 J 2040 2030 A J 2030 2020 MPI J 2020 2010 400 A J 2010 2000 ETH MPI J M 2001 2011 2021 2031 2041 2051 2061 2071 2081 2091 J S A J SMHI A J A -10 METNO A J 2000 -5 DMI METNO J -10 5 DJF -20 0 -5 0 DJF -20 0 -5 -5 humidity % smhi mpi metno hc eth dmi 0 depth [m] depth [m] 0 -10 -10 2091 5 2081 0 2071 -5 2061 -10 2051 -15 2041 SON 2031 SON 2021 SON 2011 SON 2001 DJF 1991 DJF Duration of snow pack > 10 cm [days] DJF 2091 DJF Figure 1: Seasonal differences between RCM’s and observations at Schilthorn and Murtèl which were used to downscale the regional climate model output according to the delta method. Table 1 RCM's and GCM's used by the 6 institutes of ENSEMBLES project which were chosen for the study -5 MAM 2081 MAM JJA 2071 JJA smhi mpi metno hc eth dmi 2061 MAM smhi mpi metno hc eth dmi 2051 MAM JJA The projected snow cover (> 10cm) at the two sites shows a general decrease in duration of about 50 to 80 days per year during the 21st century (Figure 4). The onset of the snow cover is delayed and the time that the sites become snow-free is earlier than observed in the recent years (Figure 3). For the Schilthorn site the scenarios of DMI, ETH and HC show that the active layer varies between 5m and 12m until around 2020 (Figure 2). After that period, the thaw layer does not freeze up anymore and a talik develops. The scenarios of MPI and SMHI show no stable permafrost condition after 1998. The METNO scenario predicts stable permafrost until 2050. For the Murtèl site the scenarios DMI, ETH, SMHI show an increase of active layer depth from 2.5m to around 7m in 2090. The METNO scenario shows no change until 2050. HC and MPI predict the development of a talik at the Murtèl site in the late 21st century. incoming longwave radiation W/m² 2041 JJA smhi mpi metno hc eth dmi smhi: 2239.0 m a.s.l.; mpi: 2247.4 m a.s.l.; metno: 2194.8 m a.s.l.; hc: 1365.0 m a.s.l.; eth: 2245.0 m a.s.l.; dmi: 1772.3 m a.s.l. measured: 2910 m a.s.l. depth [m] ETH smhi mpi metno hc eth dmi -100 depth [m] DMI 0 -10 -20 -30 -40 -50 -60 -70 -80 0 -10 -20 -30 -40 -50 -60 -70 -80 0 -10 -20 -30 -40 -50 -60 -70 -80 air temperature (altitude corrected) °C incoming longwave radiation W/m² 2031 HIRHAM CLM HadRM3Q0 HIRHAM REMO RCA depth [m] ARPEGE HadCM3Q0 HadCM3Q0 BCM ECHAM5-r3 HadCM3Q3 depth [m] 0 -10 -20 -30 -40 -50 -60 -70 -80 0 -10 -20 -30 -40 -50 -60 -70 -80 0 -10 -20 -30 -40 -50 -60 -70 -80 Danish Meteorological Institute Swiss Federal Institute of Technology Hadley Centre for Climate Prediction and Research Norwegian Meteorological Institute Max-Planck-Institute for Meteorology Swedish Meteorological and Hydrological Institute RCM depth [m] depth [m] depth [m] depth [m] DMI ETH HC METNO MPI SMHI GCM depth [m] Institute air temperature (altitude corrected) °C 2021 The sites of this study are Schilthorn in the Bernese Oberland and Murtèl in the Engadin. The sites were chosen because of their different morphologies and substrates, i.e. a rock slope with a substantial fine-grained surficial cover at Schilthorn and a bouldery surface with large blocks at rock glacier Murtèl. for the period from june 1997 to february 2008 2011 Site for the period from september 1999 to august 2008 Results 2001 The soil model is driven by meteorological parameters (air temperature, relative humidity, wind speed, incoming short-wave radiation, incoming long-wave radiation, and precipitation). A complete energy balance is calculated for the snow or soil surface, yielding a surface temperature representing the upper thermal boundary condition of the soil profile. A constant geothermal heat flux determines the lower thermal boundary. The model includes the accumulation and melt of a seasonal snow cover, as well as freezing and thawing of the soil. The model has been driven by daily mean values of meteorological parameters taken from the output data of 6 different RCM runs (ENSEMBLES Project) for the time period of 1991 to 2050/2098. The seasonal bias in relation to the measured climate data has been determined on the basis of an observation period from 1999 to 2008 for Schilthorn and from 1997 to 2008 for Murtèl (Figure 1). The relative deviations have been corrected in the soil model input for air temperature, incoming short-wave radiation, incoming long-wave radiation, wind speed and precipitation. Murtèl 1991 In this study a one dimensional coupled heat and mass transfer model of the soil snow atmosphere boundary layer (COUP Model) is used to simulate the evolution of two high alpine permafrost sites in Switzerland under the influence of climate change as projected by regional climate models (RCM’s). Schilthorn Duration of snow pack > 10 cm [days] Model Snow height [m] Introduction 2060 2070 2080 2090 S Figure 4: Projected duration of snow cover (>10cm) for Schilthorn and Murtèl. 2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 Figure 3: Hovmöller diagrams of the projected snow cover according to the 6 chosen RCM runs (left side Schilthorn, right side Murtèl). The x-axis shows years from 1991 to 2098, the y-axis shows days of year starting in September. The contour lines represent the simulated snow height with the bold orange line indicating a height of 50cm. References ENSEMBLES Project. http://ensemblesrt3.dmi.dk/ Jansson P-E, Karlberg L. 2001. Coupled heat and mass transfer model for soil-plant-atmosphere systems. Royal Institute of Technology, Dept of Civil and Environmental Engineering, Stockholm.