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30 March 1994, Volume 6 Issue 1 Previous Issue    Next Issue
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OCCURRENCE OF THE ASSEMBLAGE GRANDIDIERITE, KORNERUPINE,AND TOURMALINE IN ANTARCTICA 1994, 6 (1):  4-10.  Abstract ( 1322 )   PDF (235KB) ( 1234 )   Grandidierite, kornerupine,and tourmaline occur in high grade pelitic gneisses from the Larsemann Hills,East Antarctica. The three minerals contact to each other and show a special order:Trn 1→Gdd→Trn 2→Krn→Trn 3,suggesting the occurrence of the assemblage is controlled by the temporal changes of the chemical potentials of B 2O 3 and H 2O.The discovery of the minerals is a good constraint on the setting and composition feature of metamorphism in the area. Related Articles | Metrics

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A COMPARATIVE STUDY ON THE IONOSPHERIC CURRENT SYSTEMS IN THE ANTARCTIC AND ARCTIC REGIONS 1994, 6 (1):  11-19.  Abstract ( 1349 )   PDF (220KB) ( 1040 )   The current systems representing the solar and lunar daily variations (S and L)of the geomagnetic field have been calculated on the basis of the date obtained from the global network of geomagnetic observatories.The characteristics of these current systems in the Antarctic and Arctic regions have been analysed comparatively. The results show that:(1)There are certain differences in the current systems of these two regions,that implies definite differences in the ionospheric dynamo process,responsible for both S and L,and the field-aligned current,responsible for S.The differences of the magnetic field structure in these two polar regions may be the basic reason of the above mentioned differences.(2)There are remarkable differences in the internal current systems of these two polar regions,that is attributed to both the inducing field ( current) and the underground conductivity.In general,the conductivity of the Antarctic region is higher than that of the Arctic region. Related Articles | Metrics

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IONOSPHERIC EFFECTS OF THE MARCH 13,1989 MAGNETIC STORM AT SUBAURORAL REGION 1994, 6 (1):  20-27.  Abstract ( 1397 )   PDF (403KB) ( 1283 )   Ionograms and magnetograms at Great Wall (62°13′S,58°58′W),Antarctica,were used to study the sub auroral ionospheric effects of the March 13,1989 magnetic storm.The virtual height of the F region (h′F) increased and the critical frequency(f 0F 2) decreased rapidly just after the storm's sudden commencement(SSC).Then the spread F appeared and lasted about five hours. During the main phase of the magnetic storm the ionosphere encountered severe absorptions,but large enhancements in h′F and associated depressions in f 0F 2 sometimes were still observed.On the second and third nights after the SSC auroral type sporadic E and night E layers were observed,showing peak electron densities as high as 7.5×10 5el cm -3 .The causes of these phenomena are discussed. Behaviours of h′F and f 0F 2 from four ionosonde stations in the same longitude sector ( Great Wall,Port Stanley,Cachoeira Paulista and Fortaleza) show that the higher the station's latitude is, the more severe absorptions occure, and the longer the depressions of f 0F 2 last. Related Articles | Metrics

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THE GROWTH OF CHICK IN THE SOUTH POLAR SKUA AND SOME FACTORS INFLUENCING IT NEAR THE ZHONGSHAN STATION ,EAST ANTARCTICA 1994, 6 (1):  28-37.  Abstract ( 1159 )   PDF (258KB) ( 961 )   The growth of chicks of South Polar skua Catharacta maccormicki near the Zhongshan Station was observed in 1989/1990 austral summer. The breeding period was going through from mid-December to mid-February next year.The survival rate of chicks was very lower and it was 38.9% in this study season.For about 53.2 days (range 52-55 days) breeding ,the chicks grew up and were able to fly,the average daily growth rate was 27.42g/d and 16.56g/d with first and second chicks respectively.The logistic curve was fitted to the weight data for typical growth.The equation is: W=1255.41+22.6034e -0.1518t The important factors influencing chick's growth and mortality were discussed in this paper.They are food,unfavourable weather and predation by adult skuas. Related Articles | Metrics

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SCANNING ELECTRON MICROSCOPIC ANALYSIS ON EGG SHELL OF ADELIE PENGIUN,PYGOSCELIS ADELIAE 1994, 6 (1):  38-42.  Abstract ( 1361 )   PDF (189KB) ( 1218 )   An analysis is made of the fine structure and element composition of egg shell of adélie pengiun, Pygoscelis adeliae by SEM and EDX. The results show that the outer and inner surfaces of the egg shell are irregular platelet like cortex and compactly reticulated fibriform endomembrane respectively. There are three layer structures, in which the texture and compostion exist distinct differences, between the outer cortex and the endomembrane. Among them,the outer and mid layer are mainly composed of calcium carbonate and a small amount of calcium phosphate, The content of calcium and phosphorus is Ca: 95.81% and 97.81%, P:4.19%and 1.87%, SEM observations reveal that the calcium carbonatecalcite layer structure in the outer layer is similar to that in egg shell of other birds or reptiles. However, the main component of the inner layer in the egg shell of adelie pengiun, which is greatly different from the egg shell of other birds or reptiles, is calcium sulphate, containing up to 84.26% sulphur. Related Articles | Metrics

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GENERAL CHARACTERISTICS IN STRATIGRAPHY AND DENSITY VARIATION FOR ICE CORES FROM COLLINS ICE CAP, KING GEORGE ISLAND,ANTARCTICA 1994, 6 (1):  43-49.  Abstract ( 1232 )   PDF (198KB) ( 912 )   It was proven by the stratigraphy of two ice cores from Collins Ice Cap that the summit of Main dome(with elevation of 700m or so) belongs to warm infiltration zone,while that of Small dome(with elevation of 250m or so)to infiltration zone.A certain dating information could be found from the distribution of snow and ice layers along the ice core. The curve of density against depth for the ice core from the summit of Main dome showed regular variation corresponding to the distibution of melt features in stratigraphic record.The annual layers was roughly determined consequently.It was estimated that the accumulation rate in snow thickness at the summit of Main dome was 3-3.5m,which was about 1650-1925kg/m 2·a in water equivaleat and 2.0m/a in mean ice thickness equivalent.The transition depth of snow to ice there was 38-39m, above it density increased gradually downward,but at rather high rate below that depth, due to appearance of water table, reaching 900kg/m 3 in 5-6m interval.The density data of the ice core from the summit of Small dome showed the fluctuation between 800 and 900kg/m 3 except that of the very surface part, in which the snow and ice interleaved frequently and dust layers existed.These suggested that the accmulation rate at the summit of Small dome was about 0.7m/a in ice equivalent and the transition depth of snow to ice is 7-8m,covering about 10 year's mass cumulated.Very thick volcanic deposition layers were discovered at the depth below 40m in the ice core from the the summit of Samll dome. Related Articles | Metrics

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A PRIMARY ANALYSIS OF MASS BALANCE CHARACTERISTICS ON SMALL DOME OF COLLINS ICE CAP,KING GEORGE ISLAND,ANTARCTICA 1994, 6 (1):  50-60.  Abstract ( 1266 )   PDF (254KB) ( 995 )   Some mass balance characteristics on small dome of Collins Ice Cap were analyzed according to a full year measurement data of mass balance on small dome of the ice cap in 1991/1992.The small dome belongs to the type of glacial mass supplied in cold season,periods of accumulation and ablation were distinguished clearly.Although the range of the height of small dome is not large,the melting period at terminal was two months longer than that at the top; Amount of ablation in warm season decreased rapidly with increase of the height.Affected mainly by the undulation of glacial surface, accumulation in cold season varied remarkably.Mass balance at SDS section in 1991/1992 was a weak positive balance year with a mass balance difference of 163 mm,altitude of equilibrium line was 140m,which was 20m lower than that of dynamic equilibrium line.Mass balance characteristics showed larger mass balance gradient,lower mass balance level and smaller stability coefficient,which reflected the distinctive property of glacial mass balance under the condition of subpolar maritime climate. Related Articles | Metrics

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THE DELAY MEASUREMENTS AND THE PROPAGATION PATHS INVESTIGATION OF THE TIMMING SIGNALS FROM MOSCOW AND IRKUTSK TO ANTARCTIC GREAT WALL STATION 1994, 6 (1):  61-65.  Abstract ( 1337 )   PDF (249KB) ( 1168 )   In this paper the measurement method of radio wave propagation delay with the timming signals from RWM(Moscow) and RID(Irkutsk) station to Antarctic Great Wall Station is introduced. Then according to the propagation delay data measured from April 1991 to September 1991 the propagation paths are analyzed. The propagation time blocks along the long and short great circle paths are illustrated. It is recognized that there are non great circle path propagation, and its behaviour are explained. We make an approach to the occurrence condition for non great circle path propagation. Related Articles | Metrics