Ninth International Conference on Permafrost ... - IARC Research

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Historical Changes in the Seasonally Frozen Ground Regions of the Russian ArcticOliver W. Frauenfeld, Tingjun Zhang, Andrew J. Etringer, Roger G. BarryCIRES National Snow and Ice Data Center, University of Colorado, Boulder, Colorado, USADavid GilichinskySoil Cryology Laboratory, Institute of Physico-Chemical and Biological Problems in Soil Sciences,Russian Academy of Sciences, Pushchino, Moscow Region, RussiaIntroductionSeasonal freezing and thawing processes in cold regionsplay an important role in ecosystem diversity, productivity,and the Arctic hydrological system (Hinzman et al. 1991,Kane et al. 1991, Woo 1992, Osterkamp et al. 2000, Nelson2003). Long-term changes in seasonal freeze and thaw depthsare also useful indicators of climate change (Frauenfeld etal. 2004). However, only sparse historical measurements ofseasonal freeze and thaw depths are available for permafrostand seasonally frozen ground regions. In previous work, weapplied mean monthly soil temperature data for 1930–1990at 242 sites located throughout Russia, and employed asimple interpolation scheme to determine the depth of the0°C isotherm based on soil temperature data measured at 13depths between 0.2 m and 3.2 m. The relationship betweenavailable observed annual maximum freeze and thaw depthsand our interpolated values indicates a perfect correlation,and thereby verifies our methodology (Frauenfeld et al.2004).In this analysis, we improve on our previous work byemploying a greatly expanded station database with soiltemperatures for 423 sites with updated observations throughthe year 2000. These 423 stations are located throughoutRussia (Fig. 1) and can be obtained from the Frozen GroundData Center (http://nsidc.org/fgdc/). The addition of 181sites throughout the Russian Arctic combined with 10more years of observations allows for a significantly morecomprehensive evaluation. Furthermore, the addition of1991–2000 allows us to quantify changes in the soil thermalregime during a decade when accelerated climate warminghas potentially occurred.Data and MethodsDetailed descriptions of soil temperature measurementsin the former Soviet Union were provided by Gilichinskyet al. (1998), by Zhang et al. (2001), and in the instructionmanuals of the State Committee of the U.S.S.R. forHydrometeorology and Environmental Control (1985).Observations are available for the 0.2 m, 0.4 m, 0.6 m, 0.8m, 1.2 m, 1.6 m, 2.0 m, 2.4 m, and 3.2 m depths. We linearlyinterpolated the depth of the 0ºC isotherm throughout the0.2 m–3.2 m temperature profile (recognizing that this isnot necessarily the same as the “true” freeze/thaw depth).The 423 stations were first classified as either permafrostor seasonally frozen ground, depending on soil temperatureat the 3.2 m depth. If, for the entire record, a station’s soiltemperature at 3.2 m was positive, that station was classifiedas a seasonally frozen ground station; 387 of the 423 stationsFigure 1. Location of the 428 soil temperature observing sites inRussia.qualified. We also employ kriging to improve data quality andin-fill missing observations, and produce nearly continuousstation time series for 1930–2000. For the seasonally frozenground stations, the freeze depth was interpolated betweenthose layers where the temperature switched from negativeto positive. The maximum depth of freezing was selectedfrom the months of March, April, and May only. An averagetime series was generated by averaging all available stations’maximum annual freezing depth departures (with respectto each station’s long-term mean) in the seasonally frozenground region of the Russian Arctic. Linear least-squaresregression was then applied to the time series to quantify itslong-term changes.Results and DiscussionIn our previous work the long-term trend for the 1930–1990 period based on 211 seasonally frozen groundstations indicated a decrease in seasonal freeze depths ofapproximately 4.4 cm decade −1 , or 27 cm overall (Fig. 2).This trend is statistically significant (95%-level). However,because prior to the mid-1950s there were too few stationsto produce a robust trend (Fig. 2), this 27 cm change had tobe interpreted cautiously. Based on the 1956–1990 period,when 100 or more stations contribute to each year’s meanvalue, the overall change is approximately -34 cm (notshown). Note that while a total of 211 stations were availableto generate the time series, a maximum of 158 stationscontribute at any given year, as most individual station timeseries are incomplete and have gaps due to missing data.With the addition of 176 new sites in seasonally frozenground regions, more data for the original 211 sites, and75
Ni n t h In t e r n at i o n a l Co n f e r e n c e o n Pe r m a f r o s tMaximum Annual Freeze Depth Departure (m)0.50.40.30.20.10-0.1-0.2-0.3-0.4-0.51930 1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000YearFigure 2. Mean 1930–1990 time series, based on a total of 211stations, of the maximum annual freeze depth departures. Includedalso is the linear trend (-4.4 cm decade −1 ). The number of stationscontributing to each year’s mean value is indicated by the greybars.Maximum Annual Freeze Depth Departure (m)0.50.40.30.20.10-0.1-0.2-0.3-0.4-0.51930 1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000YearFigure 3. Mean 1930–2000 time series, based on a total of 387stations, of the maximum annual freeze depth departures. Includedalso is the linear trend (-4.0 cm decade −1 ). The number of stationscontributing to each year’s mean value is indicated by the greybars.our kriging efforts, we are now able to provide much morerobust trend estimates. As shown in Figure 3, up to 320 (ofthe total 387) stations now contribute to each year’s meanfreeze depth departure. For the same period as shown inFigure 2, 1930–1990, the trend indicates a decrease of only17 cm in seasonal freeze depth (not shown). It appears as ifthe early period prior to 1956 indeed biased our long-termtrend estimation in our earlier work. However, the 1956–1990 trend, based on these more complete data, shows anoverall decrease of 48 cm. This change is 30% greater thanpreviously reported in Frauenfeld et al. (2004).The overall change for the 71-year period from 1930–2000is a statistically significant (95%-level) -4.0 cm decade −1 , oran overall decrease of 29 cm (Fig. 3). Interestingly, this timeseries also indicates some patterns of interdecadal variability(and we need to exercise caution, therefore, in applyinglinear regression). Freeze depths actually increased slightlyuntil ~1970, followed by a sharp decrease until ~1990. From3202802402001601208040032028024020016012080400Station CountStation Count1990 on, freeze depths may actually be increasing again. Inour ongoing efforts, we are trying to establish the degreeto which these interdecadal patterns are real or potentiallycaused by changes in the amount and quality of availabledata.AcknowledgmentsThis work was funded by the U.S. National ScienceFoundation under grants ARC-0612431, OPP-0229766, andOPP-0352910, and the <strong>International</strong> Arctic Research Center,University of Alaska Fairbanks, under the auspices of theNSF cooperative agreement number OPP-0327664.ReferencesFrauenfeld O.W., Zhang, T., Barry, R.G. & Gilichinsky. D.2004. Interdecadal changes in seasonal freeze andthaw depths in Russia. J. Geophys. Res. 109: D05101,doi:10.1029/2003JD004245.Gilichinsky, D.A. et al. 1998. A century of temperatureobservations of soil climate: Methods of analysisand long-term trends. In: A.G. Lewkowicz & M.Allard (eds.), Proceedings of the 7th <strong>International</strong><strong>Conference</strong> on Permafrost, Ste.-Foy, Canada: Centred’Études Nordiques, Université Laval, 313-317.Hinzman, L.D., Kane, D.L, Gieck, R.E. & Everett, K.R.1991. Hydrologic and thermal properties of the activelayer in the Alaskan Arctic. Cold Reg. Sci. Technol.19: 95-110.Kane, D.L., Hinzman, L.D. & Zarling, J.P. 2003. Thermalresponse of the active layer to climatic warming in apermafrost environment. Cold Regions Sci. Technol.19: 111-122.Nelson, F.E. 2003. (Un)frozen in time. Science 299: 1673-1675.Osterkamp T.E., Viereck, L., Shur, Y., Jorgenson, M.T.Racine, C., Falcon, L., Doyle, A. & Boone, R.D.2000. Observations of Thermokarst and its Impacton Boreal Forests in Alaska, U.S.A. Arct. Antart. Alp.Res. 32: 303-315.State Committee of the U.S.S.R. for Hydrometeorologyand Environmental Control. 1985. Instructionsfor Meteorological Stations and Posts Vol. 3, Part1 in Meteorological Observations at Stations,Gidrometeoizdat, Leningrad.Woo, M.-K. 1992. Impacts of Climatic Variability andChange on Canadian Wetlands. Can. Water Resour.J. 17: 63-69.Zhang, T., Barry, R.G., Gilichinsky, D., Bykhovets, S.S.,Sorokovikov, V.A. & Ye. J. 2001. An amplified signalof climatic change in soil temperatures during the lastcentury at Irkutsk, Russia. Clim. Change 49: 41-76.76
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ContentsPreface ...................
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Mapping and Modeling the Distributi
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Satellite Observations of Frozen Gr
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xiiIce Wedge Thermal Regime in Nort
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xivPermafrost Response to Dynamics
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NICOP SponsorsUniversitiesUniversit
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Deep Permafrost Studies at the Lupi
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Effect of Fire on Pond Dynamics in
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Cryological Status of Russian Soils
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Acoustical Surveys of Methane Plume
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Permafrost Delineation Near Fairban
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Preparatory Work for a Permanent Ge
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A Provisional Soil Map of the Trans
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Martian Permafrost Depths from Orbi
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Time Series Analyses of Active Micr
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Impact of Permafrost Degradation on
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DC Resistivity Soundings Across a P
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Modeling Thermal and Moisture Regim
Page 46 and 47: A Provisional Permafrost Map of the
Page 48 and 49: Alpine Permafrost Distribution at M
Page 50 and 51: Cryogenic Formations of the Caucasu
Page 52 and 53: Modeling Potential Climatic Change
Page 54 and 55: A Hypothesis: A Condition of Growth
Page 56 and 57: Modeled Continual Surface Water Sto
Page 58 and 59: Freeze/Thaw Properties of Tundra So
Page 60 and 61: Discontinuous Permafrost Distributi
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Page 72 and 73: A Permafrost Model Incorporating Dy
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Page 78 and 79: The Importance of Snow Cover Evolut
Page 80 and 81: The Account of Long-Term Air Temper
Page 82 and 83: The Combined Isotopic Analysis of L
Page 84 and 85: Adaptating and Managing Nunavik’s
Page 86 and 87: Human Experience of Cryospheric Cha
Page 88 and 89: HiRISE Observations of Fractured Mo
Page 90 and 91: A Soil Freeze-Thaw Model Through th
Page 92 and 93: Mapping and Modeling the Distributi
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Page 98 and 99: Rock Glaciers in the Kåfjord Area,
Page 100 and 101: Snowpack Evolution on Permafrost, N
Page 102 and 103: Climate Change in Permafrost Region
Page 104 and 105: Maximizing Construction Season in a
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