Harold Victor Serson (1926-1992)

... Harold first went to the Arctic in 1944 as a Hudson's Bay Company seaman aboard the Nascopie. Thus began a lifelong association with the Arctic. In 1945 he joined the Department of Transport as a radiosonde technician. In 1947 he transferred to the Defence Research Board (DRB) Radio Propagation Laboratory and was one of the first people to winter-over at the newly established joint Canada-U.S.A. weather station at Resolute Bay. Subsequently, he became involved in ionospheric research at the DRB Radio Physics Laboratory, the Prince Alberta Radar Laboratory and the Telecommunications Establishment. As a technician and later technical officer he coauthored a number of papers on radio propagation in the auroral zone. In 1961, Harold was asked to investigate the abandoned Soviet drifting station NP-7, then located in Baffin Bay. That experience led to a meeting with Dr. G. Hattersley-Smith, of the DRB Directorate of Physical Research, and a significant career change. Harold began working in High Arctic oceanography and glaciology and quickly established a reputation in remote arctic science operations and logistics. ... In 1981 he retired from government service. However, he was not the type of person who could ever properly retire and turn his back on his beloved Arctic, as I was fortunate enough to soon learn. I was privileged to be able to work with Harold throughout the 1980s, .... I shall always remember the experiences we had together and will always be indebted to Harold for his friendship and the knowledge he passed on to me. ... He was modest about his achievements, never expected any reward other than thanks, and never sought any honours. In 1988 he was elected a Fellow of AINA in recognition of his significant contributions to High Arctic research. This was the least that could be done for someone who served Canadian arctic science with quiet dedication for almost five decades. Harold will be missed but, I hope, not forgotten

Ice Shelf Studies off Northern Ellesmere Island, Spring 1983

In spring 1983 work on the ice shelves of northern Ellesmere Island was continued. A total of 55 m of 7.6 cm diameter ice core was obtained from 10 locations. The longest core of 31.79 m is composed of ice-firn and basement ice and can be divided into three distinct strata according to ice salinity. Oscillating strains in Ward Hunt Ice Shelf were measured with a wire strainmeter. It is suggested that the periodic calving of ice from Ward Hunt Ice Shelf might be related to the effects of high frequency oscillation of 35 s to 40 s. Ice conditions along 150 km of coastline continue to change. Continued monitoring of the ice is believed to be necessary in view of the offshore development in the Beaufort Sea.Key words: Ward Hunt Ice Shelf, Milne Ice Shelf, ice cores, strainmeter, coastal ice conditionsMots clés: plateau de glace Ward Hunt, plateau de glace Milne, carottes glaciales, glace saline, jauge extensiométrique, conditions glaciales des côte

Ice Island Calvings and Ice Shelf Changes, Milne Ice Shelf and Ayles Ice Shelf, Ellesmere Island, N.W.T.

Analysis of vertical air photographs taken in 1959 and 1974 reveals that a total of 48 sq km, involving 3.3 cubic km, of ice calved from Milne and Ayles ice shelves between July 1959 and July 1974. In addition, Ayles Ice Shelf moved to about 5 km out of Ayles Fiord. It still occupied this exposed position in July 1984. The ice losses and movements have allowed the growth of thick sea ice that has developed an undulating topography similar to but smaller scale than that of the ice shelves. It is suggested that regular monitoring of the coastal ice of northern Ellesmere Island would enable such changes to be registered and assessed, as they could be of concern to offshore operations in the Beaufort Sea.Key words: air photographs, Milne Ice Shelf, Ayles Ice Shelf, ice island calvings, thick sea ice growthMots clés: photographies aériennes, plateau de glace Milne, plateau de glace Ayles, vêlage d'îles glaciales, formation de glace marine épaiss

Bathymetric Mapping of Shallow Water in Thaw Lakes on the North Slope of Alaska with Spaceborne Imaging Radar

Few bathymetric maps are available for the thousands of thaw lakes on the North Slope of Alaska. We describe a semiautomated procedure for bathymetric mapping of water up to 2 m deep (i.e., less deep than the maximum ice thickness) in these lakes. A sequence of ERS-1 synthetic aperture radar (SAR) images and a simulated ice growth curve for winter 1991-92 are used to derive a digital elevation model of lake basins. The method is based on discriminating between floating ice and grounded ice in the SAR images to define raw isobaths; assigning an ice thickness or water depth to each isobath from the simulated ice-growth curve, and interpolating to create equally spaced (0.25 m) isobaths. There is modest agreement between SAR-derived maps and the few available bathymetric maps. Differences between the SAR maps and the original maps are probably unavoidable because of different production methods and original data formats. The concept of using SAR and a simulated ice-growth curve for bathymetric mapping of thaw lakes would benefit from verification based on a comparison with new maps derived from accurate field measurements at a selection of lakes with different morphological characteristics. Nevertheless, it is concluded that this technique is sound and could be used routinely for inexpensive and accurate bathymetric mapping across the entire North Slope and elsewhere (e.g., in Siberia, where large numbers of thaw lakes also occur). Such mapping would greatly increase the amount and spatial coverage of bathymetric data and would provide an accurate baseline against which to detect changes in the size, shape, bottom topography, and location of lakes.Peu de cartes bathymétriques sont disponibles pour les milliers de lacs thermokarstiques situés sur le versant Nord de l'Alaska. On décrit une procédure semi-automatisée pour la cartographie bathymétrique de l'eau jusqu'à une profondeur de 2 m (c.-à-d., inférieure à l'épaisseur maximale de la glace) dans ces lacs. On utilise une séquence d'images prises au radar à antenne synthétique (SAR) ERS-1 ainsi qu'une courbe simulée de croissance de la glace pour l'hiver 1991-1992 afin d'obtenir un modèle numérique d'altitude des bassins lacustres. La méthode est fondée sur la discrimination entre la glace flottante et la glace échouée, sur les images SAR, en vue de définir des isobathes brutes; sur l'attribution d'une épaisseur de glace ou d'une profondeur d'eau à chaque isobathe obtenue à partir de la courbe simulée de croissance de la glace, et sur l'interpolation visant à créer des isobathes équidistantes (0,25 m). Il existe une légère concordance entre les cartes issues du SAR et les quelques cartes bathymétriques disponibles. Des différences entre les cartes SAR et les cartes originales sont probablement inévitables en raison de la diversité des méthodes de production et du format des données originales. L'idée d'utiliser le SAR et une courbe simulée de croissance de la glace pour la cartographie bathymétrique des lacs thermokarstiques tirerait profit d'une vérification fondée sur une comparaison avec de nouvelles cartes issues de mesures précises effectuées sur le terrain à des lacs choisis pour leurs différentes caractéristiques morphologiques. On conclut néanmoins que c'est une bonne technique qui pourrait être utilisée couramment pour la cartographie bathymétrique économique et précise de l'ensemble du versant Nord et d'ailleurs (p. ex., en Sibérie, où l'on trouve nombre de lacs thermokarstiques). Une telle cartographie augmenterait de beaucoup la quantité et la couverture spatiale des données bathymétriques et offrirait une référence précise par rapport à laquelle il serait possible de détecter les changements dans la taille, la forme, la topographie du fond des lacs ainsi que leur emplacement

Recent Changes at the Front of Ward Hunt Ice Shelf, Ellesmere Island, N.W.T.

It has been known for some time that the ice shelves of northern Ellesmere Island are the primary source of ice islands. The last major ice island calving occurred at the front of Ward Hunt Ice Shelf (WHIS) between August 1961 and April 1962 (Hattersley-Smith, 1963). Other important, but previously undocumented, changes to Milne and Ayles Ice shelves have recently been noted. During field investigations in spring 1982 and 1983 further changes were observed at the front of WHIS. ..

A New Association of Post-T Tauri Stars Near The Sun

Observing ROSAT sources in 20 x 25 deg centered at the high latitude active star ER Eri, we found evidences for a new young nearby association (~30Myr at~60pc), the Horologium Association (HorA), formed by at least 10 probable and 6 possible members, some being Post-T Tauri stars. We examine several requirements that characterize a young association and they, together, create a strong evidence for the reality of the HorA. In fact, the Li line intensities are between those of the oldest classical T Tauri stars and the ones of the Local Association stars. The space velocities of the HorA relative to the Sun, U= -9.5+/-1.0, V = -20.9 +/- 1.1, W = -2.1 +/- 1.9, are not far from those of the Local Association. We suggest that some hotter and non-X-ray active stars, with similar space velocities, could be massive members of the HorA, among them, the nearby Be star Achernar. The maximum of the mass distribution function of the HorA is around 0.8 solar masses. At its distance, the projected size of the HorA, ~50 pc, would be larger than our surveyed area and many other members could have been missed. We also observed 3 control regions, two at northern and southern galactic latitudes and a third one in the known TW Hya Association (TWA), and the properties and distribution of their young stars strengthen the reality of the HorA. Contrary to the TWA, the only known binaries in the HorA are 2 very wide systems. The HorA is much more isolated from clouds and older than the TWA and could give some clues about the lifetime of the disks around T Tauri stars. Actually, none of the proposed members is an IRAS source indicating an advanced stage of the evolution of their accreting disks. ER Eri itself was found to be a RS CVn-like system.Comment: 25 pages, 5 eps figures, to appear in Astron.