Pole Station Research Articles

Behaviour of HILAT scintillation over spitsbergen

Results of the amplitude scintillation morphology of the HILAT satellite 137 MHz beacon transmission as measured at the Polish Polar Station at Hornsund, Spitsbergen ( Δ = 73.4°) are presented. Seasonal, diurnal and latitudinal dependencies of scintillation intensity on magnetic activity were analyzed from over 2250 satellite passes recorded at solar minimum between April 1985 and March 1986. Regions with strong scintillation intensity appear to follow the auroral oval expansion and to move sunward with increasing level of magnetic activity. Maximum amplitude scintillation region coincides with the dayside cusp/cleft position during high magnetic activity. The dawn-dusk asymmetry in scintillation intensity is more distinct in winter than other months. The estimated summer/winter ratio of scintillation intensity is 1.4: 1. Numerical simulations compared with the observational results indicate that high latitude irregularities < 1 km are field-aligned and rod-like rather than sheet-like.

Heavy metals and sulphur in mosses from southern Spitsbergen

Concentrations of Cd, Pb. Ni, Cu. Zn and S were determined in 16 moss species collected from 9 localities in southern Spitsbergen (mostly within the Hornsund region). Two species, Sanionia uncinata and Hylocomium splendens, were objects of more thorough studies. In Sanionia uncinata the mean concentrations were (ug/g): Cd-0.59, Pb-7.07, Ni-4.25, Cu-6.01. Zn-21.13 and S- 1, 481. Hylocomium splendent accumulated similar quantities of these elements. The concentrations of metals and sulphur in mosses differed significantly {p0.05) from site to site, depending on geological and climatic conditions specific to the Arctic region. The effect of remote sources of pollution reaching Spitsbergen on the levels of heavy metal concentrations was taken into account, as well as the effect of local emissions from the Polish Polar Station. At 10-25 metre distances from the Station, the levels of heavy metals and sulphur were 3-10 times higher than at a 300-metre distance.

Levels of anxiety in polar environments

To test the common assumption that being part of an isolated group in the polar winter represents an anxiety-arousing environment, trait and state anxiety levels were measured in two Argentine stations in Antarctica and two Canadian sites in the High Arctic. The group scores were compared with each other, with comparison groups drawn from the same population as the polar teams but not working in isolated polar stations, and with available norms. Anxiety levels were about the same in both isolated crews, and showed no differences from the comparison groups. Data from Argentine subjects showed some differences from published U.S. norms. A sub-sample of the Antarctic comparison group was retested twice in the Antarctic during the following year. No significant changes were found in either state or trait anxiety. The data support the view that even environments that appear to be dramatically stressful cannot be assumed to have pervasive negative effects; one must look at how the individuals in the environment actually experience it.

Measurement of atmospheric opacity at 278 GHz at McMurdo Station, Antarctica in austral spring seasons, 1986 and 1987

We present a quasi-continuous record of measured atmospheric opacity obtained at 278 GHz (1.1 mm wavelength) from McMurdo Station, Antarctica during austral spring seasons in 1986 and 1987. McMurdo Station, at 78°S, 166°W, is easier to access than the Amundsen-Scott (South Pole) Station, although representing a warmer, sea level site with substantially higher typical opacity: the present record may be of interest to those contemplating mm-wave astronomical or atmospheric observations within the Antarctic region. Observations were made over a 256 MHz bandpass in 1986, during the period August 30 to October 30. In 1987, a 512 MHz bandpass was used, and observations were made during the period September 4 to October 13. All data are reduced to represent opacity in the zenith direction, and measurements were taken approximately every 20 minutes, except during storms or other periods of high opacity. The periods covered represent transitions from the polar winter towards summer conditions, and thus represent neither the best nor the worst that this site has to offer.

Human impact on tundra environment at the Ny-�lesund Station, Svalbard

Studies were performed in Ny-Alesund, Spitsbergen, in June and July 1986 in order to gain an insight into the effect of activities of the polar research station on the nearby environment. It was found that chemical and mechanical factors were the most detrimental to the tundra environment. Fuel oil spills (110 m3 in 1986), which spread via surface and ground waters, were the most damaging of the chemical factors. Domestic sewage polluted the waters of Kolhamna Bay within an area of only 0.5 ha around its outlet in the sea. Vehicles and trampling caused mechanical damage inducing destruction of plant cover and changes in the ground structure; it modified ground moisture, bulk density and depth to the permafrost. The area degraded by human activity in the vicinity of the Ny-Alesund Research Station comprised 45 ha. The human impact around the polar station could be lessened by providing an alarm system to detect leaks and safety embankments around the oil tanks and pipelines, utilizing a settling tank for sewage, providing a simple incinerator for solid wastes, and instructing the inhabitants how to minimise impact on the environment.

SOVIET GEODESISTS IN THE CENTRAL ARCTIC

The work of a recent Soviet geodetic surveying expedition to the Central Arctic and the Barents Sea off Franz Josef Land is described, with an emphasis on gravimetric surveying and determination of gravimetric control points at the North Pole and at two drifting polar research stations. In addition, glacier fields of Alexander Land (Franz Josef Land) were mapped and keys for their interpretation on space imagery identified. Translated from: Geodeziya i kartografiya, 1988, No. 3, pp. 9-12.

Ozone variations in the Northern polar region

All total ozone observations ever made in the Northern polar region, including some from the 1930's, have been corrected and the basic climatology presented. The long-term ozone changes were considered in relation to the stratospheric temperatures. For each deviation from the monthly normal of the 100 hPa temperature by 1°C, there was found to be a corresponding 5–6 m atm-cm change in the monthly ozone deviation. A distinction between the ozone regimes over the Scandinavian, Canadian and East Siberian sectors of the polar region was noted. The strong appearance of the QBO (Quasi Biennial Oscillation) in the interannual ozone fluctuations was obvious. It is demonstrated that for the past three decades the total ozone experienced a few periods with positive and a few periods with negative deviations. In view of this, trends in ozone must obviously be based on greater than 10 years of data. During 1964–86, the weighted trend over the polar stations was (−0.9±0.4)% per decade. There have been, however, three periods (1958–64, 1968–76 and 1979–86), coinciding with the declining phase of the 11 year sunspot cycle, during which the ozone at all polar stations has been declining by about 0.5% per year (or less if the QBO component is filtered out). Some of the differences with Antarctic ozone are mentioned and the dominant role of the stratospheric circulation for the ozone variations is discussed. In general the Arctic ozone observations show no evidence of a major ozone decline similar to that over Antarctica.

Annual Activity of Hans Glacier/Spitsbergen/ as Determined by Photogrammetry and Micro-Tremors Recording (Abstract)

In the period from 1982 to 1984, the Silesian University Expeditions investigated the annual cycle of the Hans Glacier velocity and front fluctuations. They also analysed the factors influencing these processes (J.Jania, L.Kolondra, E. Bukowska-Jania 1983). Surrounding the Hans Glacier frontal zone, permanent tripods had been installed (by cementation in monolithic rocks) for the photo-theodolite, to establish three stereo-photogrammetric bases. While two of the three bases were used for surveying the fluctuations of the glacier front along the entire width (ca. 2.5 km), the remaining one was installed to record the velocity of the glacier by the time-parallactic method. Photogrammetric pictures were reiterated approximately every 10 days during August in 1982, 1983 and 1984. During the polar winters of 1982/83 and 1983/84, the oscillations of the glacier front were recorded at one base only. Pictures were taken once a month (also by moonlight). Using a Gornik-type seismograph, natural micro-tremors coming from the glacier were recorded continually, The seismograph works at the nearby Polish Polar Station, which operates a meteorological station. The application of permanent metal tripods with an auto-centering disc made it possible to take successive pictures at the same external orientation of the camera on one hand, while, on the other hand, improving the convergent photographs (a similar approach was reported by U. Voigt 1966). On the glacier surface, ground points of control were signalled with a Maltese cross. The investigators made use of natural reference points, i.e. some characteristic features of the glacier surface. Maximum errors of the photogrammetric survey were mxy = ±0.3 m, mz = ±0.1 m. The results of glacier tongue velocity measurements (ca 50 ma−1), as well as the results of measuring the fluctuations of the glacier front position enabled the rate of calving to be calculated. Thus, the calving velocity amounts to ca 100 ma−1 and the mass loss at the contact with sea water approaches ca 20% of the annual mass loss due to ablation. The calving speed and the velocity of the glacier undergo variations in different periods of the year and the maxima of the processes do not overlap. While the glacier velocity reaches its maximum value at the beginning of the summer season (July), maximum calving speed is recorded in autumn (September-October). However, there may appear a shift in the time at which these maxima occur. It depends on the meteorological conditions and the thermal state of the sea in the given year. The effect produced by the two “antagonistic” glacial processes is the change in position of the glacier front in the sea. Its maximum and minimum extension appears by the end of July and in October, respectively. The amplitude of the Hans Glacier front fluctuations, measured for the period of August, 1982 to August, 1983, amounted to 60 ma−1 on the centre line. The results of photogrammetric surveying by C. Lipert, from 1957 to 1959, have shown that the maximum changes in the extension of the glacier front amount to 250 ma−1. These fluctuations display regularities similar to those reported for the Columbia Glacier, Alaska by C.S. Brown, M.F. Meier and A. Post (1982). Analyses of micro-tremors coming from the glacier involved their variability in scale and frequency from one day to the next and throughout the year, as well as photogrammetric survey. Attempts were also made to find the englacial source of those micro-tremors. Source location was attempted in the summer of 1980, by using three geophones situated in the frontal part of the glacier. Thus, the majority of the micro-tremors owe their origin to the zone situated at a distance of 200 to 300 m from the front line and not to the ice cliff, as had been expected (A. Cichowicz, personal communication). It is worth noting that there exists an overlap of the annual distribution of the frequency of micro-tremor occurrence with the curve of glacier velocity variations. This enabled the investigator to determine the glacier dynamics by tremor recording.

Annual Activity of Hans Glacier/Spitsbergen/ as Determined by Photogrammetry and Micro-Tremors Recording (Abstract)

In the period from 1982 to 1984, the Silesian University Expeditions investigated the annual cycle of the Hans Glacier velocity and front fluctuations. They also analysed the factors influencing these processes (J.Jania, L.Kolondra, E. Bukowska-Jania 1983).Surrounding the Hans Glacier frontal zone, permanent tripods had been installed (by cementation in monolithic rocks) for the photo-theodolite, to establish three stereo-photogrammetric bases. While two of the three bases were used for surveying the fluctuations of the glacier front along the entire width (ca. 2.5 km), the remaining one was installed to record the velocity of the glacier by the time-parallactic method. Photogrammetric pictures were reiterated approximately every 10 days during August in 1982, 1983 and 1984. During the polar winters of 1982/83 and 1983/84, the oscillations of the glacier front were recorded at one base only. Pictures were taken once a month (also by moonlight). Using a Gornik-type seismograph, natural micro-tremors coming from the glacier were recorded continually, The seismograph works at the nearby Polish Polar Station, which operates a meteorological station.The application of permanent metal tripods with an auto-centering disc made it possible to take successive pictures at the same external orientation of the camera on one hand, while, on the other hand, improving the convergent photographs (a similar approach was reported by U. Voigt 1966). On the glacier surface, ground points of control were signalled with a Maltese cross. The investigators made use of natural reference points, i.e. some characteristic features of the glacier surface. Maximum errors of the photogrammetric survey were mxy = ±0.3 m, mz = ±0.1 m.The results of glacier tongue velocity measurements (ca 50 ma−1), as well as the results of measuring the fluctuations of the glacier front position enabled the rate of calving to be calculated. Thus, the calving velocity amounts to ca 100 ma−1 and the mass loss at the contact with sea water approaches ca 20% of the annual mass loss due to ablation.The calving speed and the velocity of the glacier undergo variations in different periods of the year and the maxima of the processes do not overlap. While the glacier velocity reaches its maximum value at the beginning of the summer season (July), maximum calving speed is recorded in autumn (September-October). However, there may appear a shift in the time at which these maxima occur. It depends on the meteorological conditions and the thermal state of the sea in the given year. The effect produced by the two “antagonistic” glacial processes is the change in position of the glacier front in the sea. Its maximum and minimum extension appears by the end of July and in October, respectively. The amplitude of the Hans Glacier front fluctuations, measured for the period of August, 1982 to August, 1983, amounted to 60 ma−1 on the centre line. The results of photogrammetric surveying by C. Lipert, from 1957 to 1959, have shown that the maximum changes in the extension of the glacier front amount to 250 ma−1. These fluctuations display regularities similar to those reported for the Columbia Glacier, Alaska by C.S. Brown, M.F. Meier and A. Post (1982).Analyses of micro-tremors coming from the glacier involved their variability in scale and frequency from one day to the next and throughout the year, as well as photogrammetric survey. Attempts were also made to find the englacial source of those micro-tremors. Source location was attempted in the summer of 1980, by using three geophones situated in the frontal part of the glacier. Thus, the majority of the micro-tremors owe their origin to the zone situated at a distance of 200 to 300 m from the front line and not to the ice cliff, as had been expected (A. Cichowicz, personal communication). It is worth noting that there exists an overlap of the annual distribution of the frequency of micro-tremor occurrence with the curve of glacier velocity variations. This enabled the investigator to determine the glacier dynamics by tremor recording.

Tundra degradation in the vicinity of the Polish Polar Station, Hornsund, Svalbard

Studies performed in the summers of 1979 and 1980 in the surroundings of the Polish Polar Station at Hornsund, Svalbard, aimed at determining the impact of the presence of a research station on its immediate tundra surroundings. The sources of environmental degradation were singled out; the ways of expansion of various contaminants and the degree of their harmfulness to the environment were evaluated. This gave insight into the extent of tundra degradation in the vicinity of a polar research station. It was found that the heaviest impacts were caused by changes in the chemical composition of the soil, resulting from spills of petroleum-derived fuels, and by transport which damaged the surface of the tundra.

Tundra degradation in the vicinity of the Polish Polar Station, Hornsund, Svalbard

Studies performed in the summers of 1979 and 1980 in the surroundings of the Polish Polar Station at Hornsund, Svalbard, aimed at determining the impact of the presence of a research station on its immediate tundra surroundings. The sources of environmental degradation were singled out; the ways of expansion of various contaminants and the degree of their harmfulness to the environment were evaluated. This gave insight into the extent of tundra degradation in the vicinity of a polar research station. It was found that the heaviest impacts were caused by changes in the chemical composition of the soil, resulting from spills of petroleum-derived fuels, and by transport which damaged the surface of the tundra.

Possible heterogeneity of the Earth's core deduced from PKIKP travel times

The core of the Earth is usually described by spherically-symmetrical velocity models. The core is made of two main spherical layers: the fluid outer core with a radius close to 3,480 km and a P-velocity increasing with depth from 8 km s−1 to 10.3 km s−1, and the solid inner core with a radius of 1,220 km and a P-velocity close to 11 km s−1 (refs 1, 2). Station residuals of the seismic core phase PKIKP have been computed for 400 seismological observatories worldwide using 5 yr of the International Seismological Centre (ISC) Bulletins. PKIKP travel times can be corrected for upper mantle propagation by subtracting P delays; thus PKIKP–P residuals are a measurement of the average vertical travel times in the lower mantle and in the core of the Earth beneath seismic stations. A spherical harmonic development of PKIKP–P delays up to degree 4 explains 58% of the variance in the data. PKIKP–P exhibit a latitudinal dependence: polar stations tend to be faster than equatorial stations. We show here that this pattern may reflect a departure from spherical symmetry in the P-velocity distribution in the vicinity of the inner core boundary of the Earth.

Cosmic ray north‐south anisotropy: The role of the interplanetary magnetic field

Nucleonic intensity data from the north and south polar stations Thule and McMurdo are analyzed to determine the nature of periodicities in the north‐south asymmetry of relativistic galactic cosmic rays. The 24‐hour average intensity differences on individual days range from 0 to ±1.5%, and the most prominent time variation is a recurrence tendency with a period consistent with the 27‐day solar rotation period. A recently developed procedure for evaluating the statistical significance of quasi‐persistent data has been utilized to establish the reality of the 27‐day signal disclosed by superposed epoch analysis of the north‐south asymmetry data. Analyses of various components of the interplanetary magnetic field reveal that the IMF component (parallel to the nominal garden hose direction) also displays a 27‐day variation with maximum amplitude. Furthermore, a significant relationship between and the north‐south asymmetry is established by Chree analysis. On the basis of this relationship, it is suggested that the 27‐day variation in the north‐south asymmetry arises from the drift, where represents the radial gradient of cosmic rays.

Equivalent ionospheric current systems representing IMF sector effects on the polar geomagnetic field

Equivalent ionospheric current systems representing IMF sector effects on the geomagnetic field in high latitudes are examined for each of the twelve calendar months by spherical harmonic analyses of geomagnetic hourly data at 13 northern polar stations for seven years. The main feature of obtained equivalent current systems includes circular currents at about 80° invariant latitude mostly in the daytime in summer and reversed circular currents at about 70° invariant latitude mainly at night in winter. Field-aligned current distributions responsible for equivalent currents, as well as vector distributions of electric fields and ionospheric currents, are approximated numerically from current functions of equivalent current systems by taking assumed distributions of the ionospheric conductivity. Two sets of upward and downward field-aligned current pairs in the auroral region, and also a field-aligned current region near the pole show seasonal variations. Also, ionospheric electric-field propagation along geomagnetic field lines from the summer hemisphere to the winter hemisphere with auroral Hall-conductivity effects may provide an explanation for the winter reversal of sector effects.

Relativistic cosmic rays and corotating interaction regions

Analyses of relativistic galactic cosmic ray intensity variations have been conducted to determine the nature of the modulations that are related to the presence of corotating interaction regions (CIR) in interplanetary space. The corotating interaction regions have been identified from the plasma and field observations recorded by Pioneer 10 and 11 spacecrafts during the period 1972–1974. This investigation has established that the nucleonic intensity recorded at the polar stations Thule and McMurdo decreases as the streams associated with the CIR overtake the earth. However, this modulation occurs only for those CIR‐associated streams in which a neutral sheet is imbedded. In contrast, geomagnetic storms are related to CIR streams with or without neutral sheets. Taken together, these results suggest that the ostensible effect of CIR's on the intensity of high‐energy particles is primarily a consequence of drifts related to neutral sheets, although diffusion effects cannot be ruled out at this stage.

Fuel costs shut polar station

Increased fuel costs will force one of the United States' four year‐round Antarctic research stations to close in late January, near the end of the austral summer, until the beginning of the following austral summer. Siple Station, the primary U.S. Antarctic facility for upper‐atmosphere research, will assume an intermittent schedule through 1987; the station will be closed for 2 years during this time.A 114% increase in fuel costs in February prompted the budget tightening, according to Erick Chiang, field projects manager of the National Science Foundation's polar operations section. Closing Siple Station for the 1981 austral winter is only one cut being made by NSF's Antarctic research program. Other costs will be cut by deferring construction projects at McMurdo Station (a year‐round facility) to another year, indefinitely postponing repairs to an LC‐130 supply aircraft, reducing the number of remote field camp projects during fiscal 1981, and reducing cargo delivery flight hours from more than 4000 to 3200.

Cosmic ray intensity pulses

Pulse variations in the galactic cosmic ray intensity, extending over intervals of several hours, have often been observed during cosmic ray storms as well as during other periods. On some occasions, these pulses appear in the data recorded at polar stations during epochs characterized by enhanced diurnal anisotropy at low latitudes. The short‐term intensity increase at polar stations cannot be ascribed solely to the azimuthal anisotropy, and it is demonstrated that the cosmic ray transport during a pulse displays both azimuthal and north‐south anisotropies. Furthermore, it is found that the magnitude of the pulse height recorded by a station i is proportional to eμi where μi=cos θi and θi, is the angular separation between the mean asymptotic direction of viewing of station i and the direction of anisotropy in three‐dimensional space. The relationship between pulse modulations and transient disturbances in the interplanetary magnetic field, and especially their location, remain to be investigated.

Auroral hiss on the ground atL≃ 4

Auroral hiss is rarely seen at sub-auroral-zone ground stations, but during the 4-month period January–April 1976 it became very prevalent in the wide-band, audio frequency, synoptic whistler records at Farewell, Alaska (L = 4.2). A possible reason for this is that in the normal reduction and retreat of auroral zone effects to higher latitudes at sunspot minimum the reduction in the particle precipitation which causes auroral absorption is greater than that in the softer precipitation which causes auroral hiss. The occurrence of auroral hiss at Farewell showed, at 21 hours LMT (local magnetic time), the same strong diurnal peak found at auroral zone and polar cap stations. The low-frequency cutoff of auroral hiss on the ground is also discussed.

The origin of transient cosmic ray intensity variations

A new approach to determining the solar progenitor of transient cosmic ray intensity variations has revealed that in a statistical sense, solar flares, heretofore regarded as the predominant source of the modulation, actually do not precede the reduction in flux observed at earth. Superposed epoch analysis of the cosmic ray data with respect to the time of occurrence of all 379 solar flares of importance (Imp) ≥ 2 observed during solar cycle 20 (1964–1974 inclusive) shows that the onset of a decrease in the composite nucleonic intensity at polar stations occurs prior to the zero day (i.e., time of the flare) well before the arrival in the vicinity of earth of the associated solar plasma. The statistical significance of this result is confirmed by comparing the pooled variance determined from Chree analysis of an equal number of random epochs with that of the curve representing the flare epochs. Subdivision of the latter into three groups according to the heliographic longitude of the flares shows that whereas eastern flares might be associated with cosmic ray decreases, central (30° to −30°) and western flares cannot be thus related. A similar analysis of all flares of Imp ≥ 2 that occurred in a selected set of 24 extraordinary flare-rich active centers during 1964–1974 confirms these results and shows that the observed cosmic ray intensity decrease is, in fact, associated with the central meridian passage (±1 day) of the active regions. Thus earlier conclusions concerning relationships between the heliolongitude of flares and their apparent effectiveness in producing Forbush decreases require reevaluation. The specific feature associated with solar active centers that is actually the principal source of transient modulations remains to be identified.

Polar cap geomagnetic field responses to solar sector changes

I made a computerized analysis of digitized magnetograms from Alert, Thule, Resolute Bay, Mould Bay, and Godhavn for 1965 and from Thule and Vostok for 1967 to determine the characteristic features of the day-to-day geomagnetic field variations related to the interplanetary solar sector field direction. Higher invariant latitude stations showed the sector effects most clearly. A sector-related phase shift in the characteristic diurnal variation of the field occurred principally for the dayside vertical geomagnetic component. The amplitude of this diurnal variation was related to Ap and could not be used to identify the sector direction. The quiet nighttime level of field Z component rose and fell on days when the interplanetary magnetic field was directed toward or away from the sun, respectively. When a station's base level field was determined from quiet magnetospheric conditions by using days with low values of Dst and AE indices, the mean field level of the Z component for the whole day increased or decreased (often over 100 ..gamma..) from this level as the solar sector direction was toward or away, respectively. With respect to the earth's main field direction the souther polar station field level changes were opposite those at the northern stations. Thismore » level shift corresponded with the two solar field directions during the summer months at polar stations for about 70% of the days in 1965 and 88% of the days in 1967. In 1967 the standoff locations of the magnetopause and magnetoshock boundaries were abotu 1 R/sub E/ more distant from the earth for the average toward sector days than for the away sector days. (AIP)« less