DOCSLIB.ORG

PIXELS and PINGOS: UTILIZING COMPUTER VISION to DETECT PINGOS on EARTH, MARS, and CERES. K. T. Udell1, K. Hughson1, B. E. Schmidt1, H

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
PIXELS and PINGOS: UTILIZING COMPUTER VISION to DETECT PINGOS on EARTH, MARS, and CERES. K. T. Udell1, K. Hughson1, B. E. Schmidt1, H 51st Lunar and Planetary Science Conference (2020) 2926.pdf PIXELS AND PINGOS: UTILIZING COMPUTER VISION TO DETECT PINGOS ON EARTH, MARS, AND CERES. K. T. Udell1, K. Hughson1, B. E. Schmidt1, H. G. Sizemore², J. E. C. Scully³, C. A. Raymond³, C. T. Russell⁴. ¹School of Earth and Atmospheric Sciences, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, GA 30332 ([email protected]), ²PSI, Tucson, AZ, ³JPL, Pasadena, CA, ⁴UCLA, Los Angeles, CA. Introduction: Pingos are quasi-conical mound-like structures Figure 1: Examples of terrestrial and possible martian formed through the freezing of groundwater under and cerean pingos: (a) Ibyuk pingo in northern Canada specific periglacial hydrological conditions (Figure 1). near the Mackenzie River delta, Ibyuk is ~250 m wide These dynamic water-based systems are of interest on and ~ 50 m tall; (b) a planform view of Ibyuk pingo; other planetary bodies due to the implications of the (c) a pingo candidate on Mars, adapted from [3]; (d) existence of subsurface water ice resources. two candidate pingos in southern Occator. Pingos primarily form through the injection and subsequent freezing of liquid water into the shallow Methods: subsurface either under hydrostatic or hydraulic condi- This project is a combined effort between manually tions [1]. On Earth, these conditions are met in many identifying potential pingos and pingo-shaped features periglacial environments including the Arctic coast of on Earth, Mars, and Ceres and developing a computa- northern Canada, Alaska, Russia, Svalbard, and many tional pipeline which can identify these features to a other locations. Similar landforms have been exten- level of accuracy similar to human identification using sively documented on Mars [e.g. 2 & 3] although it computer vision and machine learning techniques. remains ambiguous if these features are truly analo- gous to terrestrial pingos. Recently, new high- 1. Identifying Regions of Interest: We first identify resolution images from the final extended mission of regions of on each body which we believe may NASA’s Dawn spacecraft revealed pingo-like mor- contain Pingos using the guidance of past works. phologies within Occator and Urvara craters on the The regions identified for this study include Tuk- dwarf planet Ceres [4,5]. toyaktuk Peninsula on Earth [1], Utopia Planitia These potential hydrological systems on Mars and on Mars [2,3], and Occator and Urvara craters on Ceres may be, or could have been, important habitats Ceres [4,5]. for life or nexus for pre-biotic chemistry. Additionally, identifying and characterizing the water resource po- 2. Image Compilation: Utilizing the efforts of past tential of possible extraterrestrial pingos is relevant for works we already have a complete image mosaic future human space exploration. Previous methods of and shape model for Ceres created using data from identification of these structures are time consuming the Dawn Mission. On Earth we will identify pin- and tedious, but with the developments in machine gos using visual imagery from Planet [6] and learning we have simplified this process allowing for a ESA’s Copernicus program, as well as Arctic greater capacity for mapping pingo-like morphologies DEM [7]. On Mars we will utilize visual imagery in new and future remote sensing images and data from the Mars Reconnaissance Orbiter, particular- products of the surface of Earth, Mars, and the Ceres. ly from the HiRISE instrument. 3. Manual Mapping: Utilizing QGIS we will identi- fy pingo-like morphologies visually on each planetary body. We will measure the dimensions and planform morphology of each feature, as well as their centroids. 4. Utilizing Computer Vision: We will implement a code which will go through three steps, first iden- tifying potential mounds, second collecting meas- urements of the mound structures, and third re- finement of results to the most likely pingo candi- dates. This kind of work has already been done for craters utilizing a variety of methods, but due to the variable quality of our imagery and the size of 51st Lunar and Planetary Science Conference (2020) 2926.pdf the pingo-like morphologies we are searching for, which can help in the identification of the most methods using elevation data will not be as largely appealing candidates. applicable as they are for crater identification. We will implement our search utilizing grayscale im- 5. Code Verification: We will then check the outputs agery. Using edge-detection (Figure 2) and a of our code against the manual mapping, to deter- shape filter we can identify pingo structures, then mine the accuracy of pingo candidates that were we can isolate mounds from craters through meas- selected. Since there are very likely fewer pingo urement of the orientation of the characteristic candidates than craters on Mars and Ceres it is not crescent shape for each structure. In this part we unreasonable to manually check each output for will have to specify orientation for each body de- the purposes of this project. pending on the direction the sun is hitting the sur- face. We can use the isolated shapes to calculate References: midpoint, maximum axis and minimum axis [1] Mackay J. R. (1998) Geo. Phys et Quart., 52, 271-323. [2] length. Once again we can remove candidates Dundas C. M. & McEwen A. S. (2010) Icarus, 205, 244-258. [3] based on these factors by setting a maximum and Soare R. J. et al. (2019) Icarus, in press. [12] Scully J. E. C. et al. (In minimum size limit for our search. We also will be Review) Nat. Geo. [4] Schmidt B. E. et al. (In Review) Nat. Geo. [5] able to determine whether or not there appear to Hughson K. H. G. et al. (2020) LPSC LI. [6] Planet Team (2017). be fractures at the tops of the larger structures, Planet Application Program Interface: In Space for Life on Earth. [7] Porter C. et al. (2018) Harvard Dataverse, V1. Figure 2. Example of an edge detection algorithm applied to candidate pingo-like morphologies on Ceres (same image as that used in Figure 1d). Note how the smooth flanks of the two mounds are easily recognized by the algo- rithm. Key obstacles that need to be overcome to facilitate wide use of this technique for detecting pingo-like mor- phologies are ambiguities with impact craters and background noise. .
Load more

Recommended publications
  • Mineral Element Stocks in the Yedoma Domain
    Discussions https://doi.org/10.5194/essd-2020-359 Earth System Preprint. Discussion started: 8 December 2020 Science c Author(s) 2020. CC BY 4.0 License. Open Access Open Data Mineral element stocks in the Yedoma domain: a first assessment in ice-rich permafrost regions Arthur Monhonval1, Sophie Opfergelt1, Elisabeth Mauclet1, Benoît Pereira1, Aubry Vandeuren1, Guido Grosse2,3, Lutz Schirrmeister2, Matthias Fuchs2, Peter Kuhry4, Jens Strauss2 5 1Earth and Life Institute, Université catholique de Louvain, Louvain-la-Neuve, Belgium 2Permafrost Research Section, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Potsdam, Germany 3Institute of Geosciences, University of Potsdam, Potsdam, Germany 4Department of Physical Geography, Stockholm University, Stockholm, Sweden 10 Correspondence to: Arthur Monhonval ([email protected]) Abstract With permafrost thaw, significant amounts of organic carbon (OC) previously stored in frozen deposits are unlocked and 15 become potentially available for microbial mineralization. This is particularly the case in ice-rich regions such as the Yedoma domain. Excess ground ice degradation exposes deep sediments and their OC stocks, but also mineral elements, to biogeochemical processes. Interactions of mineral elements and OC play a crucial role for OC stabilization and the fate of OC upon thaw, and thus regulate carbon dioxide and methane emissions. In addition, some mineral elements are limiting nutrients for plant growth or microbial metabolic activity. A large ongoing effort is to quantify OC stocks and their lability in permafrost 20 regions, but the influence of mineral elements on the fate of OC or on biogeochemical nutrient cycles has received less attention. The reason is that there is a gap of knowledge on the mineral element content in permafrost regions.
    [Show full text]
  • Periglacial Processes, Features & Landscape Development 3.1.4.3/4
    Periglacial processes, features & landscape development 3.1.4.3/4 Glacial Systems and landscapes What you need to know Where periglacial landscapes are found and what their key characteristics are The range of processes operating in a periglacial landscape How a range of periglacial landforms develop and what their characteristics are The relationship between process, time, landforms and landscapes in periglacial settings Introduction A periglacial environment used to refer to places which were near to or at the edge of ice sheets and glaciers. However, this has now been changed and refers to areas with permafrost that also experience a seasonal change in temperature, occasionally rising above 0 degrees Celsius. But they are characterised by permanently low temperatures. Location of periglacial areas Due to periglacial environments now referring to places with permafrost as well as edges of glaciers, this can account for one third of the Earth’s surface. Far northern and southern hemisphere regions are classed as containing periglacial areas, particularly in the countries of Canada, USA (Alaska) and Russia. Permafrost is where the soil, rock and moisture content below the surface remains permanently frozen throughout the entire year. It can be subdivided into the following: • Continuous (unbroken stretches of permafrost) • extensive discontinuous (predominantly permafrost with localised melts) • sporadic discontinuous (largely thawed ground with permafrost zones) • isolated (discrete pockets of permafrost) • subsea (permafrost occupying sea bed) Whilst permafrost is not needed in the development of all periglacial landforms, most periglacial regions have permafrost beneath them and it can influence the processes that create the landforms. Many locations within SAMPLEextensive discontinuous and sporadic discontinuous permafrost will thaw in the summer months.
    [Show full text]
  • Ground Ice Stratigraphy and Late-Quaternary Events, South-West Banks Island, Canadian Arctic H.M
    Climate and Permafrost 81 Ground ice stratigraphy and late-Quaternary events, south-west Banks Island, Canadian Arctic H.M. FRENCH Departments of Geography and Geology, University of Ottawa, Ottawa, Ontario, Canada KIN6N5 D.G. HARRY Department of Geography, University of Ottawa, Ottawa, Ontario, Canada KIN6N5 AND M. J. CLARK Department of Geography, University of Southampton, Southampton 5095NH, U.K. The stratigraphic study of pingos and ice wedges on south-west Banks Island indicates a period of continuous permafrost aggradation in late Quaternary times interrupted by a temporary period of deeper seasonal thaw in the mid-Holocene. Both epigenetic and small syngenetic ice wedges are exposed in coastal bluffs south-east of Sachs Harbour. Within the Sachs and Kellett River catchments, radiocarbon dating suggests that a number of collapsed and partially eroded pingos are relict features related to a period of climatic deterioration which commenced approximately 4000 years B.P. The stratigraphic study of ground ice is thought to be a useful method of geomorphological and paleo- environmental reconstruction, especially in areas which have experienced extended histories of cold, non-glacial conditions. L'etude stratigraphique de pingos et coins de glace dam la partie sud-ouest de I'ile Banks rCvele I'existence d'une phiode d'expansion du pergelis01 continu a la fin du Quaternaire interrompue par une periode passagtre de dCgel saisonnier plus important au milieu de 1'Holoctne. Des coins de glace CpigCnttique et de petits coins de glace syngenttique sont exposts dans les falaises cbtikres au sud-est de Sachs Harbour. Dans les bassins versants des rivihes Sachs et Kellett, la datation au radiocarbone suggtre qu'un certain nombre de pingos effondrks et en partie Crodts sont des vestiges d'une periode de dttkrioration des conditions climatiques qui a commenck il y a environ 4 000 ans.
    [Show full text]
  • The Birth and Growth of Porsild Pingo
    ARCTIC VOL. 41, NO. 4 (DECEMBER 1988) P. 267-274 The Birth and Growth of Porsilc1 Pingo, Tuktoyaktuk Peninsula, District of Mackenzie J. ROSS MACKAY’ (Received 21 March 1988; accepted in revised form I June 1988) ABSTRACT. The birth and growth of Porsild Pingo (ice-cored hill) can be taken as fairly representative of the birth and growth of the more than 2000 closed-system pingos of the western arctic coast of Canada and adjacent Alaska. Porsild Pingo, named after a distinguished arctic botanist, has grown in the bottom of a large lake that drained catastrophically about 1900. Porsild Pingo has grown up at the site of a former shallow residual pond. The “birth” probably took place between 1920 and 1930. The high pore water pressure that caused updoming of the bottom of the residual pond to give birth to Porsild Pingo came from pore water expulsion by downward and upward permafrost growth in saturated sands in a closed system. In the freeze-back period of October-November 1934, permafrost ruptured and the intrusion of water into the unfrozen part of the active layer grew a 3.7 m high frost mound photographed by Porsild in May 1935. Porsild Pingo has grown up at, or very close to, the site of the former frost mound. The growth of Porsild Pingo appears to have been fairly steady from 1935 to 1976, after which there has been a decline to 1987. The growth rate has been nearly linear with height, from zero at the periphery to a maximum at the top. The present addition of water to the pingo is about 630 m’.y”.
    [Show full text]
  • Sub-Permafrost Methane Seepage from Open System Pingos in Svalbard Andrew J. Hodson1,2, Aga Nowak1, Mikkel T. Hornum1,3, Kim
    Sub-permafrost methane seepage from open system pingos in Svalbard Andrew J. Hodson1,2, Aga Nowak1, Mikkel T. Hornum1,3, Kim Senger1, Kelly Redeker4, Hanne H. Christiansen1, Søren Jessen3, Peter Betlem1, Steve F. Thornton5, Alexandra V. Turchyn6, Snorre Olaussen1, Alina Marca7 5 1Department of Arctic Geology, University Centre in Svalbard (UNIS), N-9171 Longyearbyen, Norway. 2Department of Environmental Science, Western Norway University of Applied Sciences, Røyrgata 6, N-6856 Sogndal, Norway 3Department of Geosciences and Natural Resource Management, University of Copenhagen, 1350 Copenhagen K, Denmark. 10 4Department of Biology, University of York, YO10 5DD, UK. 5Department of Civil and Structural Engineering, University of Sheffield, S10 2TN, UK. 6Department of Earth Sciences, University of Cambridge, CB2 3EQ, UK. 7School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ, UK. 15 Correspondence to: Andrew J. Hodson ([email protected]) Abstract. Methane release from beneath lowland permafrost represents an important uncertainty in the Arctic greenhouse gas budget. Our current knowledge is arguably best-developed in settings where permafrost is being inundated by rising sea level, which means much of the methane is oxidised in the water column before it reaches the atmosphere. Here we provide a different process perspective that is appropriate for Arctic fjord valleys, where local deglaciation causes isostatic uplift to out-pace rising 20 sea level. We describe how the uplift induces permafrost aggradation in former marine sediments, whose pressurisation results in methane escape directly to the atmosphere via ground water springs. In Adventdalen, Central Spitsbergen, we show how the springs are historic features, responsible for the formation of open system pingos, and capable of discharging brackish waters enriched with high concentrations of mostly biogenic methane (average 18 mg L-1).
    [Show full text]
  • Tundra Polygons. Photographic Interpretation and Field Studies in North-Norwegian Polygon Areas
    Tundra polygons. Photographic interpretation and field studies in North-Norwegian polygon areas. By Harald Svensson Introduction. When working with aerial photos, the interpreter very soon realizes that the vegetation adjusts itself very well to differences in the ground conditions, which is in this way registered in photography. This fact constituted one of the starting points when the author, with the help of aerial photos, began the search for large-scale patterned ground of the tundra polygon shape, which earlier had not been identified in Scandinavia.1 In Arctic regions, recent tundra polygons can be clearly distinguished on aerial photographs which is a well-known fact derived from numerous investigations (amongst others, Troll 1944, Washburn 1950, Black 1952, Andreev 1955, Hopkins, Karlstrom et al 1955). The fact that there are considerable changes in the soil caused by the frost (cf. Figs. 1, 2 and 3) supports the hypothesis that, if a polygonal pattern of the tundra type developed in an area and this, at a later date in a milder climate, came to lic outside the tundra zone, it should be possible to trace fossil polygons or fragments of such with the help of the adjustment of the vegetation to the ground conditions. This idea has been followed up in order to in vestigate the correctness of the hypothesis and in order to check the possibility of this method. 1) In vertical sections and gravel-pits, however, fossil periglacial formations have been observed and studied particularly in Denmark and Southern Sweden (Norvang and Johnsson). As regards Swedish investigations of patterned ground reference is made to the surveys by Rapp and Rudberg (1960) and J.
    [Show full text]
  • The Ground Was Frozen Then
    THE GROUND WAS FROZEN THEN Overview: Students learn how permafrost shapes the landscape and how changes in permafrost affect not just the land, but also the traditions of those who live there. Objectives: The student will: • complete a labeled diagram of a permafrost feature; • interpret two types of graphs that show data related to permafrost temperature; • interview a local Elder or culture bearer to lean about traditional uses of permafrost; and • compare and contrast local tradition with that of another region in Alaska. Targeted Alaska Performance Measures Tested on the Alaska High School Qualifying Exam (HSQE): Math M6.3.2 Interpret and analyze information found in newspapers, magazines, and graphical displays. M6.3.4 Make projections based on available data and evaluate whether or not inferences can be made given the parameters of the data. M10.3.1 Apply mathematical skills and processes to science and humanities. Targeted Alaska Grade Level Expectations: Science [11] SA1.1 The student develops an understanding of the processes of science by asking questions, predicting, observing, describing, measuring, classifying, making generalizations, analyzing data, developing models, inferring, and communicating. [11] SD1.2 The student demonstrates an understanding of geochemical cycles by integrating knowledge of the water cycle and biogeochemical cycling to explain changes in the Earth’s surface. Vocabulary: active layer – the top portion of ground that thaws during the summer and refreezes in winter borehole – a narrow shaft drilled in
    [Show full text]
  • PERMAFROST Bob Carson June 2007
    PERMAFROST Bob Carson June 2007 LAKE LINNEVATNET THE ACTIVE LAYER IS FROZEN ACTIVE LAYER PERMAFROST YUKON TERMS • PERMAFROST • PERIGLACIAL • \ • PATTERNED GROUND • POLYGONS • PALS • PINGO • ROCK GLACIER • THERMOKARST YAKIMA HILLS PROCESSES • FREEZE-THAW • FROST CRACK • FROST SHATTER • FROST HEAVE • FROST SHOVE • FROST SORT • CREEP • SOLIFLUCTION • NIVATION BEARTOOTH MOUNTAINS FROST CRACK • LOW-TEMPERATURE CONTRACTION ALASKA PHOTO BY RUTH SCHMIDT FROST SHATTER • WATER EXPANDS DURING FREEZING VATNAJOKULL KHARKHIRAA UUL FROST HEAVE FROST PUSH vs. FROST PULL CAIRNGORM FROST SHOVE GREENLAND PHOTO BY W.E. DAVIES FROST SORT SWEDISH LAPLAND PHOTO BY JAN BOELHOUWERS C R E E P SHARPE 1938 SOLIFLUCTION SOLIFLUCTION LOBES HANGAY NURUU NIVATION NIVATION HOLLOWS PALOUSE HILLS LANDFORMS WITH ICE ALASKA PHOTO BY SKIP WALKER AUFEIS KHARKHIRRA UUL HANGAY NURUU ICE WEDGES sis.agr.gc.ca/.../ground ICE-WEDGE POLYGONS res.agr.canada PALSEN HANGAY NURUU PALSEN FIELD OGILVIE MOUNTAINS PINGOES BEAUFORT COAST ALASKA PHOTO BY H.J.A. Berendsen ougseurope.org/rockon/surface/img PINGOES IN CANADIAN ARCTIC www.rekel.nl www.mbari.org www.arctic.uoguelph.ca VICTORIA ISLAND PHOTO BY A. L. WASHBURN ROCK GLACIERS GALENA CREEK ROCK GLACIERS GALENA CREEK ROCK GLACIERS GRAYWOLF RIDGE THERMOKARST YUKON THERMOKARST ALASKA ICE-WEDGE TRENCH YUKON ICE-WEDGE TRENCH ALASKA PHOTO BY JOE MOORE BEADED DRAINAGE ALASKA PHOTO BY RUTH SCHMIDT THAW LAKES PRUDOE BAY THAW LAKES ALASKA PHOTO BY ART REMPEL MORE PERIGLACIAL LANDFORMS SPITSBERGEN PHOTO BY BEN SCHUPACK WHITMAN ‘07 BLOCK FIELDS RINGING ROCKS BLOCK SLOPES BLOCK FIELD TALUS BLOCK SLOPE ELKHORN MOUNTAINS BLOCK STREAMS SAN FRANCISCO MOUNTAINS 11 June 2007 BLOCK STREAMS HANGAY NURUU CRYOPLANATION TERRACES HANGAY NURUU CRYOPLANATION TERRACES NIVATION TOR SOLIFLUCTION HANGAY NURUU PATTERNED GROUND: COMPONENTS FINES STONES HANGAY NURUU STONES: PEBBLES COBBLES BOULDERS FINES: CLAY, SILT, SAND PATTERNED GROUND: HANGAY COMPONENTS NURUU PATTERNED GROUND: CLASSIFICATION • SLOPE: HORIZONTAL± vs.
    [Show full text]
  • The Dalton Highway
    Te DaDallHtt ooi g nnh w a y Visitor Guide Road Conditions . pages 6-7 Points of Interest . .page 8 Bear Safety . .page 16 Contents Ultimate Road Adventure Trip Planning The Dalton Highway is a rough, industrial road that begins 84 miles/134 km north of Fairbanks and ends 414 miles/662 km later in 4 Preparing and Safety Deadhorse, the industrial camp at Prudhoe Bay. It provides a rare 6 Mileage Chart opportunity to traverse a remote, unpopulated part of Alaska to the 11-14 Maps very top of the continent. Traveling this farthest-north road involves real risks and challenges. This publication will help you decide 23 Planning Your Trip whether to make the journey, how to prepare, and how to enjoy your experience. Please read this information carefully. Exploring Know Before You Go 8-11 Points of Interest • There is no public access to the Arctic Ocean from Deadhorse. 15 An Icebound Land You must be on an authorized tour. Call toll-free 1-877-474-3565; 17 Watching Wildlife in Fairbanks, 474-3565. 18 Recreation • There are no medical facilities between Fairbanks and Deadhorse, a distance of 500 miles/800 km. For emergency information, see the back page. Facilities and Services • Food, gas, and vehicle repair service are extremely limited. 5 Visitor Centers See page 5. 18 Campgrounds • There is limited cell phone service and public Internet connection between Fairbanks and Deadhorse. The Dalton Highway BLM Coordinator: Kelly Egger Contributors: Eugene Ervine, Lenore Heppler, Lisa Shon Jodwalis, Craig McCaa, Pam Rice. John Rapphahn, Crystal Glassburn, Jason Oles, Jason Post Produced and Designed by All photos courtesy of the BLM unless otherwise noted.
    [Show full text]
  • Numerical Modelling of Permafrost Spring Discharge and Open-System Pingo Formation Induced by Basal Permafrost Aggradation Mikkel T
    Numerical modelling of permafrost spring discharge and open-system pingo formation induced by basal permafrost aggradation Mikkel T. Hornum1,2, Andrew J. Hodson1,3, Søren Jessen2, Victor Bense4, Kim Senger1 1Department of Arctic Geology, The University Centre in Svalbard (UNIS), N-9171 Longyearbyen, Norway. 5 2Department of Geosciences and Natural Resource Management, University of Copenhagen, 1350 Copenhagen K, Denmark. 3Department of Environmental Science, Western Norway University of Applied Sciences, N-6856 Sogndal, Norway 4Department of Environmental Sciences, Wageningen University, 6708PB Wageningen, Netherlands. Correspondence to: Mikkel T. Hornum ([email protected]) Abstract 10 In the high Arctic valley of Adventdalen, Svalbard, sub-permafrost groundwater feeds several pingo springs distributed along the valley axis. The driving mechanism for groundwater discharge and associated pingo formation is enigmatic because wet- based glaciers are not present in the adjacent highlands and the presence of continuous permafrost seem to preclude recharge of the sub-permafrost groundwater system by either a sub-glacial source or a precipitation surplus. Since the pingo springs enable methane that has accumulated underneath the permafrost to escape directly to the atmosphere, our limited understanding 15 of the groundwater system brings significant uncertainty to predictions of how methane emissions will respond to changing climate. We address this problem with a new conceptual model for open-system pingo formation wherein pingo growth is sustained by sub-permafrost pressure effects, as related to the expansion of water upon freezing, during millennial scale basal permafrost aggradation. We test the viability of this mechanism for generating groundwater flow with decoupled heat (1D- transient) and groundwater (3D-steady-state) transport modelling experiments.
    [Show full text]
  • Pingos and Palsas: a Review of the Present State of Knowledge
    Polar Geography ISSN: 0273-8457 (Print) (Online) Journal homepage: https://www.tandfonline.com/loi/tpog19 Pingos and palsas: A review of the present state of knowledge Albert Pissart To cite this article: Albert Pissart (1985) Pingos and palsas: A review of the present state of knowledge, Polar Geography, 9:3, 171-195, DOI: 10.1080/10889378509377249 To link to this article: https://doi.org/10.1080/10889378509377249 Published online: 23 Dec 2008. Submit your article to this journal Article views: 17 View related articles Citing articles: 5 View citing articles Full Terms & Conditions of access and use can be found at https://www.tandfonline.com/action/journalInformation?journalCode=tpog20 PINGOS AND PALSAS: A REVIEW OF THE PRESENT STATE OF KNOWLEDGE Albert Pissart (Department of Geomorphology and Quaternary Geology, University of Liege) From: Inter-Nord, No. 17,1985, pp. 21-32. Abstract: The article presents a summary of the present state of knowl- edge of perennial periglacial mounds, including descriptions of the external appearance and internal composition of pingos and palsas and a discussion of the genetic mechanisms. Pingos appear to be the result of the freezing of a mass of water trapped beneath permafrost under cryostatic or hydraulic pressure. Palsas are formed by the migration of groundwater to a freezing plane (cryosuction). The existence of mineral palsas is recognized; in this case the peat cover may be extremely thin or even totally non-existent. INTRODUCTION Pingos and palsas are periglacial mounds which can exist only in the presence of permafrost. Both types of mound correspond to local accumulations of ice which have raised overlying surficial layers of earth materials.
    [Show full text]
  • Spatial Analyses of Thermokarst Lakes and Basins in Yedoma Landscapes of the Lena Delta
    Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | The Cryosphere Discuss., 5, 1495–1545, 2011 The Cryosphere www.the-cryosphere-discuss.net/5/1495/2011/ Discussions doi:10.5194/tcd-5-1495-2011 © Author(s) 2011. CC Attribution 3.0 License. This discussion paper is/has been under review for the journal The Cryosphere (TC). Please refer to the corresponding final paper in TC if available. Spatial analyses of thermokarst lakes and basins in Yedoma landscapes of the Lena Delta A. Morgenstern1, G. Grosse2, F. Gunther¨ 1, I. Fedorova3, and L. Schirrmeister1 1Alfred Wegener Institute for Polar and Marine Research, Telegrafenberg A43, 14473 Potsdam, Germany 2Geophysical Institute, University of Alaska Fairbanks, 903 Koyukuk Drive, Fairbanks, AK 99775-7320, USA 3Arctic and Antarctic Research Institute, Otto Schmidt Laboratory for Polar and Marine Research, Beringa st. 38, 199397 St. Petersburg, Russia Received: 19 April 2011 – Accepted: 28 April 2011 – Published: 16 May 2011 Correspondence to: A. Morgenstern ([email protected]) Published by Copernicus Publications on behalf of the European Geosciences Union. 1495 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Abstract Distinctive periglacial landscapes have formed in late-Pleistocene ice-rich permafrost deposits (Ice Complex) of Northern Yakutia, Siberia. Thermokarst lakes and thermokarst basins alternate with ice-rich Yedoma uplands. We investigate different 5 thermokarst stages in Ice Complex deposits of the Lena River Delta using remote sensing and geoinformation techniques. The morphometry and spatial distribution of thermokarst lakes on Yedoma uplands, thermokarst lakes in basins, and thermokarst basins are analyzed, and possible dependence upon relief position and cryolithologi- cal context is considered.
    [Show full text]