Ninth International Conference on Permafrost ... - IARC Research

More documents

Recommendations

Info

Surface Ice and Snow Disappearance in Alpine Cirques and Its PossibleSignificance for Rock Glacier Formation: Some Observations from Central AustriaAndreas Kellerer-PirklbauerInstitute of Geography and Regional Science, University of Graz, AustriaIntroductionActive rock glaciers consist of two components: ice(congelation and/or sedimentary ice including “glacier”ice) and lithological material (periglacially and/or glaciallyderivedrock fragments of different grain size). Consideringtheir long formation period (centuries to millennia) andcommon climate variability (e.g., temperature, precipitation)in such long time scales, rock glaciers experience strongvariations in the rate of nourishment as well as the ratiobetween ice and debris input to the rock glacier system.Studies on the climate of rock glaciers reveal that themean annual air temperature at the rooting zone of activerock glaciers is usually only slightly higher (if at all) than atnearby equilibrium line altitudes (ELA) of normal glaciersand/or the annual precipitation is only slightly lower thanat nearby ELA (e.g., Haeberli 1983). This indicates the highsensitivity of rock glacier development to cooler and/ormore humid conditions and their close relationship to normalglaciers. However, knowledge regarding incipient formation,entire development period, variations in nourishment rate,and the ratio between ice and rock input seen over a longtime span is still far from being complete.This paper presents data on surface ice and snowdisappearance since the Little Ice Age (LIA) at twoneighboring cirques in the Central Alps of Austria. Today,one houses a rock glacier and one, a debris-covered glacierremnant. Observations and measurements on thicknessvariations and thermal conditions of the supraglacial debriscover, on landforms formed from this supraglacial material,and on buried sedimentary ice add to the understanding ofrock glacier formation and development.Study Area and Applied MethodsKögele Cirque and Hinteres Langtal CirqueThe study area consists of the two neighboring cirquesKögele Cirque (KC) and Hinteres Langtal Cirque (HLC) locatedin the central part of the Schober Mountains (46°59′N,12°47′E), Central Alps (Fig. 1). The study area is characterizedby crystalline rocks and a continental climate (1500mmat 2000m asl, 0°C mean annual air temperature at 2300 ma.s.l.) causing minor glaciation but a high abundance ofrock glaciers. Both cirques are oriented towards the westnorthwest,each with comparable high crests and mountainsummits (>3000 m a.s.l.) to the south and east (Fig. 1). TheHLC is dominated by the Hinteres Langtalkar Rock Glacier(HLRG) which at its front indicates the local lower limit ofdiscontinuous permafrost at 2450 m a.s.l. In contrast, theKC is located some 50 m higher, lacks a rock glacier, buthouses a glacier remnant (for details see Kellerer-Pirklbauer& Kaufmann 2007).MethodsThe spatial extent of surface areas covered by glaciers andperennial snow at both cirques was reconstructed for the fourstages—c. 1850 (LIA-maximum), 1969, 1997, and 2006—by using morphological evidences (LIA-moraine ridges), airphotographs (1969, 1997), and field mapping (Sept. 2006).Massive sedimentary ice outcrops in the HLC weremapped between summer 2003 and 2007 during fieldwork.In 2006, the thickness of the supraglacial debris mantle inthe KC was quantified by digging through and measuringthe debris layer to solid ice at 34 sites. These data were usedto interpolate the debris cover thickness in the KC, applyingthe Inverse Distance Weighted interpolator in ArcGIS.To monitor near-surface temperatures in the supraglacialdebris cover, two 3-channel miniature temperature dataloggers(MTLs) (Ge oPr e c i s i o n) were installed in 2006 at 2690m a.s.l. (KC1) and 2710 m a.s.l. (KC2) in the KC (Fig. 2).Three temperature sensors (PT1000; accuracy +/-0.05°C)were connected to each MTL. The two MTLs operated correctlyduring the entire period 12.09.2006–25.07.2007, loggingvalues every 0.5 h at depths 0–50 cm (KC1: 0, 10, and50 cm; KC2: 0, 10, and 20 cm). The lowest sensor at siteKC2 was placed at the debris/ice boundary.Results and Some Related CommentsSurface ice disappearance since 1850In 1850 A.D., both cirques were covered by glaciers and perennialsnow fields covering 0.21 km² of the KC and 0.18 km²of the HLC. In 1969, ice/snow still covered 0.12 km² of theKC and 0.06 km² of the HLC, but by 1997 these values werereduced to 0.06 km² (KC) and 0.01 km² (HLC). In 2006, theextent of surface ice/snow was reduced to a few small patchesin the HLC and covered less than 0.01 km² of the KC (Fig. 1).Supraglacial debris cover and buried sedimentary iceThe supraglacial debris cover in the KC was formedduring the last decades by periglacially- and paraglaciallyderivedsediments from the steadily enlarging supraglacialslopes above the shrinking ice mass. The debris cover iscurrently relatively thin and increases in thickness downvalley, exceeding 70 cm at the lower part of the mapped area(Fig. 2). In contrast to the KC, surface and near-surface (
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 tTable 1. Summarized temperature conditions at different depthsat the two sites in the KC for the period 13.09.2006–25.07.2007(10.5 months) based on MTLs. MPT = mean period temperaturein °C; DTF-Max = maximum daily temperature fluctuation duringthis period in Kelvin; FDD = freezing degree days; TDD = thawingdegree days. The snow cover duration was estimated based on lowtemperature fluctuations (for locations of the MTLs see Fig. 2).KC1 (snow cover 1.5 months)KC2 (snow cover 4 months)DepthMPTDTF-MaxFDDTDDDepthMPTDTF-MaxFDDTDDFigure 1. The two cirques Kögele Cirque (KC) and Hinteres LangtalCirque (HLC) and their extent of surface ice and snow in c. 1850,1969, 1997, and 2006. The location of the Hinteres Langtalkar RockGlacier/HLRG (in 2002) is indicated. Findings of sedimentary icesince 2003 in the HLC are asterisked: *1 = in 2006 – below 30 cmof debris; *2 = in 2006 and 2007 – a c. 20 m long and 10 K at thesurface, 4–5 K at 10 cm depth, 2.2 K at 20 cm depth (at K2at the ice/debris boundary), and less than 1 K at 50 cm at K1,indicating a substantial damping effect of the debris layer.The lowest sensors at both sites reveal low thawing degreeday/TDD values which can be explained by the proximity tothe underlying buried ice mass and by a thin active layer atthese sheltered locations at such high altitudes.Long-term landscape dynamics: KC versus HLCThe data presented here confirm the fact that, already,slightly different topoclimatic conditions are sufficient togenerate over a long time span a rock glacier in one cirqueand a normal glacier in the neighbouring cirque. The rateof ice and debris input to the cirque during the past wasdominated by the former in the KC, whereas probably bythe latter in the HLC. A thin active layer helps to preservea degrading debris-covered glacier remnant. Subsequentincorporation of such a debris-covered ice mass into a rockglacier body might be regarded as an important nourishmentfactor; at least this could have been the case at the HLRG.AcknowledgmentsThis study was carried out within the framework of theproject ALPCHANGE (www.alpchange.at) financed by theAustrian Science Fund (FWF). The air photographs (1969,1997, and 1998) were kindly provided by Viktor Kaufmann.ReferencesHaeberli, W. 1983. Permafrost-glacier relationships in theSwiss Alps: Today and in the past. Proceedings, 4thIntl. Conf. on Permafrost, Fairbanks, AK, July 17–22:415-420.Kellerer-Pirklbauer, A. & Kaufmann, V. 2007. Paraglacial talusinstability in recently deglaciated cirques (SchoberGroup, Austria). Proceedings, 9th Intl. Symposium HighMountain Remote Sensing Cartography (HMRSC-IX),Graz, Austria, Sept. 14–22, 2006: 121-130.130
Page 1:
NICOP 2008 Ninth <
Page 6 and 7:
ContentsPreface ...................
Page 8 and 9:
Mapping and Modeling the Distributi
Page 10 and 11:
Satellite Observations of Frozen Gr
Page 13 and 14:
xiiIce Wedge Thermal Regime in Nort
Page 15 and 16:
xivPermafrost Response to Dynamics
Page 17 and 18:
xvi
Page 19 and 20:
NICOP SponsorsUniversitiesUniversit
Page 22 and 23:
Deep Permafrost Studies at the Lupi
Page 24 and 25:
Effect of Fire on Pond Dynamics in
Page 26 and 27:
Cryological Status of Russian Soils
Page 28 and 29:
Acoustical Surveys of Methane Plume
Page 30 and 31:
Permafrost Delineation Near Fairban
Page 32 and 33:
Preparatory Work for a Permanent Ge
Page 34 and 35:
A Provisional Soil Map of the Trans
Page 36 and 37:
Martian Permafrost Depths from Orbi
Page 38 and 39:
Time Series Analyses of Active Micr
Page 40 and 41:
Impact of Permafrost Degradation on
Page 42 and 43:
DC Resistivity Soundings Across a P
Page 44 and 45:
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
Page 62 and 63:
Thermal Regime Within an Arctic Was
Page 64 and 65:
Seasonal and Interannual Variabilit
Page 66 and 67:
Twelve-Year Thaw Progression Data f
Page 68 and 69:
Continued Permafrost Warming in Nor
Page 70 and 71:
Landsliding Following Forest Fire o
Page 72 and 73:
A Permafrost Model Incorporating Dy
Page 74 and 75:
Seasonal Sources of Soil Respiratio
Page 76 and 77:
Greenland Permafrost Temperature Si
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
Page 94 and 95:
First Results of Ground Surface Tem
Page 96 and 97:
Historical Changes in the Seasonall
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
Page 106 and 107: Pleistocene Sand-Wedge, Composite-W
Page 109 and 110: Ni n t h In t e r n at i o n a l Co
Page 149: Ni n t h In t e r n at i o n a l Co
Page 159 and 160: Ni N t h iN t e r N at i o N a l Co
Page 201 and 202:
Ni n t h In t e r n at i o n a l Co
Page 203 and 204:
Page 205 and 206:
Page 207 and 208:
Page 209 and 210:
Page 211 and 212:
Page 213 and 214:
Page 215 and 216:
Page 217 and 218:
Ni N t h iN t e r N at i o N a l Co
Page 219 and 220:
Page 221 and 222:
Page 223 and 224:
Page 225 and 226:
Page 227 and 228:
Page 229 and 230:
Page 231 and 232:
Page 233 and 234:
Page 235 and 236:
Page 237 and 238:
Page 239 and 240:
Page 241 and 242:
Page 243 and 244:
Page 245 and 246:
Page 247 and 248:
Page 249 and 250:
Page 251 and 252:
Page 253:
Page 257 and 258:
Page 259 and 260:
Page 261 and 262:
Page 263 and 264:
Page 265 and 266:
Page 267 and 268:
Page 269 and 270:
Page 271 and 272:
Page 273 and 274:
Page 275 and 276:
Page 277 and 278:
Page 279 and 280:
Page 281 and 282:
Page 283 and 284:
Page 285 and 286:
Page 287 and 288:
Page 289 and 290:
Page 291 and 292:
Page 293 and 294:
Page 295 and 296:
Page 297 and 298:
Page 299 and 300:
Page 301 and 302:
Page 303 and 304:
Page 305 and 306:
Page 307 and 308:
Page 309 and 310:
Page 311 and 312:
Page 313 and 314:
Page 315 and 316:
Page 317 and 318:
Page 319 and 320:
Page 321 and 322:
Page 323 and 324:
Page 325 and 326:
Page 327 and 328:
Page 329 and 330:
Page 331 and 332:
Page 333 and 334:
Page 335 and 336:
Page 337 and 338:
Page 339 and 340:
Page 341 and 342:
Page 343 and 344:
Page 345 and 346:
Page 347 and 348:
Page 349 and 350:
Page 351 and 352:
Page 353 and 354:
Page 355 and 356:
Page 357 and 358:
Page 359 and 360:
Page 361 and 362:
Page 363 and 364:
Page 365 and 366:
Page 367 and 368:
Page 369 and 370:
Page 371 and 372:
Page 373 and 374:
Page 375 and 376:
Page 377 and 378:
Page 379 and 380:
Page 381 and 382:
Page 383 and 384:
Page 385 and 386:
Page 387 and 388:
Page 389 and 390:
Page 391 and 392:
370Huang, B. 339Hugelius, G. 105, 1
Page 393:
372
show all

Ninth International Conference on Permafrost ... - IARC Research

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?