World Glacier Inventory - Inventaire mondial des Glaciers (Proceedings of the Riedeialp Workshop, September 1978: Actes de l'Atelier de Riederalp, septembre 1978): IAHS-AISH Publ. no. 126, 1980.

Satellite image atlas of glaciers

J. G. Ferrigno and R. S. Williams, Jr

Abstract The US Geological Survey has initiated a project to prepare a satellite image atlas of glaciers with the cooperation of a number of US and international organizations. The atlas will include the geographical distribution of glaciers as well as topics of glaciology and related environmental phenomena using Landsat, NOAA and other satellite data. The primary objectives of the atlas are to provide an inventory of available images of extant glaciers, to demonstrate their scientific value and to serve as the basis of Landsat image maps of glacierized areas.

Atlas des images de glaciers transmises par satellite Résumé. Un projet ayant pour but la préparation d'un atlas des images de glaciers transmises par satellite a été lancé par le US Geological Survey avec la coopération de plusieurs organisations américaines et internationales. L'atlas contiendra la répartition géographique des glaciers, de même que des matières ayant trait à la glaciologie et aux phénomènes de l'environnement en rapport avec celle-ci, en utilisant les données de Landsat, NOAA et d'autres satellites. Les objectifs principaux de l'atlas sont la mise à disposition d'un inventaire des images disponibles de glaciers existants, la démonstration de leur valeur scientifique et l'établissement d'une base de référence pour les cartes-images Landsat de régions englacées.

INTRODUCTION

In June 1977, the Earth Resources Observation Systems (EROS) programme of the US Geological Survey's (USGS) Land Information and Analysis Office (LIA) initiated a 3-year project to prepare a USGS Professional Paper, Satellite Image Atlas of Glaciers. The Glaciology Project Office (Tacoma, Washington) of the Water Resources Division (WRD) of the USGS and the National Environmental Satellite Service (NESS) of the National Oceanic and Atmospheric Administration (NOAA) were also directly involved in the preparation of the atlas from the early conceptual stages. As the project progressed, several additional US and international organizations indicated their willingness to be included in the authorship of the atlas.

Sufficient Landsat, NOAA, and other satellite data now exist to compile a Satellite Image Atlas of Glaciers, and the preparation of such an atlas is considered a timely effort because of the wide variety of impending and ongoing US and international climatology studies. The primary objective of the atlas is to provide a pictorial and tabular inventory of the best available satellite images of extant glaciers. Such an atlas should provide a benchmark for: (1) future and past studies of glaciers, and (2) global climatological studies. The atlas should also be useful in providing a common data base (planimetric 'map') for locating, describing, and measuring existing glaciers. By comparing images with other images, aerial photographs, and maps over a period of time, it will also be helpful for studying the dynamics of glaciers.

ATLAS STRUCTURE

The atlas is divided into two principal parts: part I, Geographic Distribution of Glaciers and part II, Topics of Glaciology and Related Environmental Phenomena. The first part contains an introductory chapter on the classification and distribution of glaciers and

333

334 J. G. Ferrigno and R. S. Williams, Jr

11 geographic area chapters covering Antarctica, Greenland, Iceland, Europe, Asia, North America, South America, Africa, the Middle East, New Guinea, and New Zealand.

In each chapter, the best available satellite images will be evaluated and used in a discussion of the distribution of present-day glaciers and their variations together with phenomena such as glacial surges, changes caused by jokulhlaups, glacial advance or recession, ablation phenomena, variations of proglacial lakes, speed of glacier flow, etc. In areas where the glaciers are small and well known, the chapter discussion can be comprehensive. In areas of larger or less well known glaciers, it may be necessary to give a broad overview and then discuss in depth only selected examples. All of the geographic area chapters will be authored by scientists who have extensively studied the subject areas. The support and interest shown by the international glaciological community is evidenced by the overwhelmingly positive response to the request for authors.

The second part of the atlas contains a series of short topical papers on glaciers and related phenomena that can be observed on satellite imagery. They include the following: glacier dynamics and glacier hazards, variation in extent of sea ice, variation in global snow cover, periglacial phenomena, climatic variation, present and future monitoring of changes of glaciers, and the use of Landsat imagery for the inventory of glaciers. Part II will be followed by an appendix containing specific information on the different kinds of imaging spacecraft and availability of imagery from them.

Some preliminary results have already been derived from the preparation of the Satellite Image Atlas of Glaciers. Comparison of the present-day distribution of many glaciers with the available literature and published maps on a global scale has revealed a number of large discrepancies in the mapped position or areal extent of ice caps and outlet glaciers.

The remainder of this paper is devoted to presenting examples of Landsat images from Antarctica, Greenland, Iceland, and Svalbard together with a brief discussion of some of the initial research with Landsat images in each area.

ANTARCTICA

Of all the areas of glacier ice on earth, the Antarctic ice sheet (and associated shelves) is the most difficult to study scientifically. The very great size of the Antarctic ice sheet, both from an areal (approximately 13 800 000 km2 ) and a volume approximately 25-30 000 km3) viewpoint (Meier, 1974), and its severe climate present difficult and costly logistical problems to scientific research throughout the continent.

Conventional mapping projects by various countries have lagged far behind the need for accurate planimetric and topographic maps to plot scientific measurements obtained from field, aerial, and satellite surveys. In particular, the paucity of conventional topographic maps has had a serious impact on scientific research in Antarctica (Swithinbank and Land, 1976; Swithinbank, 1980). Partly in response to that problem, the Topographic Division of the US Geological Survey, the British Antarctic Survey, and the Division of National Mapping (Australia) have published experimental Landsat planimetric image maps and mosaics of Antarctica, ranging in scale from 1:1 000 000 to 1:250000 (see Fig. 1). Swithinbank etal.(l976), Swithinbank and Orheim (1977), and MacDonald (1976 a, b, c) have discussed Landsat images of Antarctica either as the base for special planimetric image maps or for monitoring dynamic changes in glaciers and ice shelves of Antarctica.

Satellite images are an excellent means of obtaining information about certain dynamic aspects of the Antarctic ice sheet, associated ice shelves, surrounding sea ice, and for showing areal changes in seaward margins of glaciers and ice shelves. Where features are resolvable (e.g. morainic features within the glacier), it is possible to

Satellite image atlas of glaciers 3 3 5

FIGURE 1. Landsat-1 image (1174-19433, Band 7) of the McMurdo Sound region, Antarctica, on 13 January 1973. The image was used as a basis fox the first Landsat image map published by the US Geological Survey in 1973 at a scale of 1: 500 000 (MacDonald, 1976a).

calculate average velocity of a glacier between successive frames of Landsat images, similar to the research on the speed of an outlet glacier from Vatnajôkull in Iceland (Williams et al., 1974 and 1975). NOAA weather satellites, with a resolution of 1 k m , provide at least twice daily coverage of Antarctica. The Defense Meteorological Satellite Program (DMSP) weather satellites have a resolution of about 600 m with four times per day coverage, but the images are not always available. Meteorological satellites are important for monitoring gross changes in ice shelves, outlet glaciers, and sea ice, and in plotting the trajectory of large tabular icebergs. The ESMR (electronically scanning microwave radiometer), flown on the Nimbus-5 spacecraft since 1972, provides information on: (1) sea ice boundary; (2) sea ice concentration; (3) sea ice morphology; etc. (Zwally and Gloersen, 1977). The maximum ESMR spatial resolution at nadir is 25 X 25 km.

The glacier atlas, while discussing all the various types of satellite images of Antarctica, will stress the scientific value of Landsat images for the preparation of planimetric image maps and for scientific studies of dynamic phenomena. Landsat MSS (multispectral scanner) images and Landsat-1 and 2 RBV (return beam vidicon) images have a spatial resolution of about 80 m and Landsat-3 RBV images have a spatial resolution of about 30 m.

GREENLAND

The Landsat coverage of Greenland has been fairly good. Images of varying quality are available which cover all of the island except for a small portion on the western side of the southern tip, and the most northern parts (e.g. Peary Land), where Landsat does no t image. Daily microfiche images are being received from the new Canadian receiving station in Newfoundland, which may soon provide excellent new coverage of Green-

336 J. G. Ferrigno and R. S. Williams, Jr

land south of about 72 N, and excellent NOAA imagery is available for the northern­most regions (Wiesnet, 1980). NASA has scheduled additional Landsat imaging of the northwestern and northeastern coastal regions north of 72° N to improve the availability and quality of the images for those areas.

Although the available imagery of Greenland is seasonally different and therefore not always suitable for comparing features from one image to another, there is much available glaciological information nonetheless. The images taken at the end of the ablation season are helpful for locating the glacier margin and for mapping ablation phenomena. The winter images taken under low sun angle show some of the surface features and topography to best advantage. Cloudfree images of the inland ice sheet of Greenland contain a surprising amount of information on the subsurface topography as much as 100 km inland from the ice sheet margin. The Landsat ability to reveal features that are not obvious on larger scale aerial photography, because of the orthographic perspective from space and image scale, is important. In northern Greenland, at the limits of Landsat coverage, there are several excellent RBV images available which are particularly clear and in which glacier margins can be sharply delineated (Fig. 2). It is evident that Greenland is one of the areas where Landsat is a particularly valuable tool in the study of glaciers, especially for basic inventory work and to show dynamic change in a 'time-lapse' manner.

FIGURE 2. Landsat image (2554-17283, Band 2) of northwestern Greenland on 29 July 1976 showing the well defined edge of the Dodge Glacier in the Inglefield Land area and numerous outlet glaciers emptying into Smith Sound.

ICELAND

Approximately 10 per cent of the area of Iceland is covered by glaciers, mostly in the form of ice caps, the largest of which is Vatnajôkull with an area of about 8300 km2

(measured from Landsat images). Six other glaciers are larger than 50 km2. Many of the ice caps (e.g. Vatnajôkull, Langjôkull, Hofsjôkull, Myrdalsjôkull and Eyjafjallajôkull) are extremely dynamic with very heavy annual accumulation of snow (over 6 m per

Satellite image atlas of glaciers 337

year in the interior of Vatnajôkull), rapid movement (nearly 2 m per day for Skeidararjôkull, see Williams et al, 1975) and extensive ablation at lower elevations.

The historical record of pre-1900 observations has been well documented by Thoroddsen and Thorarinsson. Jôn Eythôrsson, with the help of farmers and other laymen, began systematic field measurements of the snouts or margins of selected glaciers in Iceland about 1930 and in 1951 he began publishing an annual report of glacier fluctuations in J'okull. After Eythôrsson's death it has been continued by Sigurjôn Rist and now includes the snouts or margins of 34 different glaciers (mostly outlet glaciers). This total, however, represents only about 10 per cent of the glaciers throughout Iceland which could be monitored annually. Obviously, systematic field observations of all of Iceland's glaciers represents a formidable task. Conventional topographic maps are infrequently revised and commonly show glaciers as fictitious composites of several years of observations (e.g. available maps of Vatnajôkull).

Landsat images of Iceland have been advantageously used by US Geological Survey and Icelandic scientists to document changes resulting from glacier surges and subglacial volcanic and geofhermal activity (Williams et al., 1974; Thorarinsson et al., 1974; Williams and Thorarinsson, 1974). They are also practical for making a rapid inventory of changes in glacier area, observing ablation features and variation in the size of proglacial lakes, and as the basis for a series of planimetric image maps of glaciers. Two 1:500 000 Landsat image maps of Vatnajôkull, one from early fall, and one from early winter, 1973, have been published by the US Geological Survey (in 1976 and 1977). Two computer-enhanced Landsat image maps of Vatnajôkull, at a scale of 1:250 000, (both versions of the early fall 1973 image) are under preparation (Williams et ah, 1977).

The RBV images from Landsat-3 will permit planimetric image maps of glaciers t o be produced at scales as large as 1:100 000. The importance of Landsat images to glacier studies can be appreciated by reference to Fig. 3 (a) and (b).

Figure 3(a).

FIGURE 3(a). Landsat image (1426-12070) of Vatnajôkull, Iceland, on 22 September 1973. The image represents conditions at the end of the summer.

338 J. G. Ferrigno and R. S. Williams, Jr

Figure 3(b).

FIGURE 3(b). Landsat image (1192-12084) of Vatnajokull, Iceland, on 31 January 1973 under low-angle (7°) solar illumination. The image represents winter conditions. Note the subtle details of surface morphology which are lacking on (a).

SVALBARD

Chapter 5 of the atlas will discuss the European glaciers including those of the Alps, Scandinavia, Jan Mayen, and Svalbard. Svalbard is another area where the use of satellite imagery is particularly valuable in glacier studies. Svalbard is located between 74° and 81°N and 10° and 35°E. Because of its isolated location, extremely variable arctic weather and seasonal variation in daylight, fieldwork and aerial photography must be closely planned within the limiting factors of season and expense. The careful use of Landsat imagery could make such planning much more efficient by pinpointing crucial areas of glacier change.

The Landsat images of Svalbard are very good. There is complete coverage of the major islands, and most of the images are excellent. Unfortunately, the data base on Svalbard is not very comprehensive. Most of the images were acquired during the summer of 1976, so the opportunities for seasonal or temporal comparisons are lacking.

It is interesting, however, to compare the Landsat images with the published maps of Svalbard. There are many discrepancies in the US Air Force 1:1 000 000 scale Operational Navigational charts (ONC maps) that are used as a global map base, not only in Svalbard but in all areas where glaciers are present. The discrepancies are not just a matter of glacier margins, etc., but concern the geographic locations of glaciers, coastlines, offshore islands, etc. This strengthens the argument for a much wider production of planimetric image maps based on Landsat imagery. When comparing Landsat images with the more recent and more accurate maps (1:500 000) of the Norsk Polarinstitutt (1968a and b, 1970a and b) there are still some discrepancies. One recent improvement on the 1976 map of Svalbard, scale 1:2 000 000, was the radical change in shape of Kvitôya. The new coastline is now based on Landsat imagery. Comparison of the glacial margins on Landsat imagery for 1976 with the Norsk Polarinstitutt maps shows a few interesting differences. Negribreen on Vest Spitsbergen,

Satellite image atlas of glaciers 339

which extends into Storfjorden, Brasvellbreen on Nordaustlandet, and Storebreen on Edgeôya (Fig. 4 (a) and (b)), and Hinlopenbreen in Olave VI Land have changed in

FIGURE 4(a). Landsat-2 image (2549-11494, Band 5) of northeastern Svalbard on 24 July 1976 showing the northeastern part of Vest Spitsbergen and part of Nordaustlandet. The ragged seaward edge of Negribreen can be seen in the bottom right corner. Brasvellbreen also terminates in the sea along a broad front in the upper right corner, (b) Landsat-2 image (2543-11155, Band 5) of eastern Svalbard on 18 July 1976 showing parts of Nordaustlandet, Vest Spitsbergen and Edgeôya. Barentsôya is in the bottom centre of the image. The seaward edge of Brasvellbreen (upper left corner), Negribreen (bottom left corner) and Storebreen (bottom right corner) are quite distinctive and differ from their portrayal on the 1 : 500 000 scale Norsk Polarinstitutt maps of Svalbard.

340 J, G. Ferrigno and R. S. Williams, Jr

outline recently and appear to have advanced. Instances like this illustrate the value of Landsat imagery as a cost effective temporal recorder of glaciological events over a wide geographic area.

REFERENCES

MacDonald, W. R. (1976a) Geodetic control in polar regions for accurate mapping with ERTS imagery. In ERTS-1: A New Window on Our Planet (edited by R. S. Williams and W. D. Carter), pp. 34-36: US Geological Survey Professional Paper, no. 929, Washington DC.

MacDonald, W. R. (1976b) Antarctic cartography. In ERTS-1, A New Window on Our Planet (edited by R. S. Williams, Jr and W. D. Carter), pp. 37-43; US Geological Survey Professional Paper, no. 929, Washington DC.

MacDonald, W. R. (1976c) Glaciology in Antarctica. In ERTS-1, A New Window on Our Planet (edited by R. S. Williams, Jr and W. D. Carter), pp. 194-195: US Geological Survey Professional Paper, no. 929, US Government Printing Office, Washington, DC.

Meier, M. F. (1974) Ice sheets and glaciers. In Encyclopaedia Britannica, 15th edition, pp. 175-186. Norsk Polarinstitutt (1968a) Vestspitsbergen (Sore Del), Svalbard, Blad 1 (map at scale 1: 500 000):

Norsk Polarinstitutt, Oslo. Norsk Polarinstitutt (1968b) Vestspitsbergen (Nordre Del), Svalbard, Blad 3 (map at scale

1: 500 000): Norsk Polarinstitutt, Oslo. Norsk Polarinstitutt (1970a) Edgebya, Svalbard, Blad 2 (map at scale 1: 500 000): N

Polarinstitutt, Oslo. Norsk Polarinstitutt (1970b) Nordaustlandet, Svalbard, Blad 4 (map at scale 1: 500 000): Norsk

Polarinstitutt, Oslo. Swithinbank, C. (1980) The problem of a glacier inventory of Antarctica. In World Glacier

Inventory (Proceedings of the Riederalp Workshop, September 1978), pp. 229-236: IAHS Publ.no. 126.

Swithinbank, C. and Land, C. (1976) Antarctic mapping from satellite imagery. In Remote Sensing of the Terrestrial Environment (edited by R. F. Peel, L. F. Curtis and E. C. Barrett), pp. 212-221; Colston Research Society, University of Bristol, Bristol.

Swithinbank, C. and Orheim O. (1977) Satellite glaciology. Polar Rec. 18.no. 116, 193. Swithinbank, C , Doakes, C, Wager, A. and Crabtree, R. (1976) Major change in the map of

Antarctica. Polar Rec. 18, no. 114, 295-299. Thorarinsson, S., Saemundsson, K. and Williams. R.S. (1974) ERTS-1 image of Vatnajôkull:

analysis of glaciological, structural and volcanic features. Jokull 23 (1973), 7-17. Wiesnet, D. R. (1980) A thermal mosaic of the Greenland ice sheet. In World Glacier Inventory

(Proceedings of the Riederalp Workshop, September 1978), pp. 343-348. IAHS Publ. no. 126.

Williams, R. S., Jr (1976) Vatnajôkull ice cap, Iceland. In ERTS-1: A New Window on Our Planet (edited by R. S. Williams, Jr and W. D. Carter), pp. 188-193: US Geological Survey Professional Paper, no. 929, US Government Printing Office, Washington, DC.

Williams, R. S., Jr and Thorarinsson, S. (1974) ERTS-1 image of the Vatnajôkull area: general comments. Jokull 23 (1973), 1-6.

Williams, R. S., Jr, Bôdvarsson, A., Fridriksson, S., Palmason, G., Rist, S., Sigtryggsson, H., Saemundsson, K., Thorarinsson, S. and Thorsteinsson, I. (1974) Environmental studies of Iceland with ERTS-1 imagery. In Proceedings of the Ninth International Symposium on Remote Sensing of the Environment, vol. 1, pp. 31-81 ; University of Michigan, Ann Arbor, Michigan.

Williams, R. S., Jr, Bôdvarsson, A., Rist, S., Saemundsson, K. and Thorarinsson, S. (1975) Glaciological studies in Iceland with ERTS-1 imagery./. Glaciol. 15, no. 73, 465-466.

Williams, R. S., Jr, Mecklenburg, T. N., Abrams, M. J. and Gudmundsson, B. (1977) Conventional versus computer-enhanced Landsat image maps of Vatnajôkull. In Abstracts with Programs, 1977 Annual Meetings, Geological Society of America, Boulder, Colorado 9, no. 7, 1228-1229.

Zwally, H. J. and Gloersen, P. (1977) Passive microwave images of the polar regions and research applications. Polar Rec. 18, no. 116, 431-450.

DISCUSSION

Swithinbank: I was most impressed by the visible flowlines that you have followed far up onto the

Satellite image atlas of glaciers 341

Greenland Inland Ice. In Antarctica we have been able to follow similar flow features 500 km inland from the coast.

Radok: ICSI independently conceived the idea of an atlas of satellite photos of glaciers and welcome the news that the US Geological Survey have already formulated appropriate plans. It has been a great pleasure to hear and see so much progress, and especially to have it presented so well by a second member of the rare species of lady glaciologists.