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With Chinese latest global gravity field model WDM 94, the authors provide the geoid height and mean free-air gravity anomaly of Antarctica (The range of latitude is from - 60° to - 90°). In order to conclude and analyze the characters of Antarctic geoid roundly, the authors collect the latest oversea global gravity field model OSU91 (to degree and order 360) and JGMOSU (to degree and order 360), get the corresponding geoid height and mean free-air gravity anomaly. The results are compared with the results got from WDM94, thus we get the difference. The standard deviation of geoid height between WDM94 and OSU91 is ± 1. 90 m; the deviation of geoid be- tween WDM94 and JGMOSU is ±2. 09 m. The standard deviation of mean gravity anomaly are i8. 97 mGal and ±9. 32 mGal respectively.
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In this paper, by using ocean surface temperature data(COADS), the study is made of the characteristics of the monthly and annual changes of the SST in the tropical western Pacific and Indian Oceans, which have important influences on the climate change of the whole globe and the relation between ENS0(E1 Niño-Southern Oscillation) and the Antarctic ice area is also discussed. The result indicates that in the tropical western Pacific and the Indian Oceans the change of Sea Surface Temperture (SST) is conspicuous both monthly and annaully, and shows different change tendency between them. This result may be due to different relation in the vibration period of SST between the two Oceans. The better corresponding relationship is obvious in the annual change of SST in the tropical Indian Ocean with the occurrence El Niño and La Nina. The change of the SST in the tropical western Pacific and the tropical Indian Oceans has a close relation to the Antarctic ice area, especially to the ice areas in the eastern-south Pole and Ross Sea, and its notable correlative relationship appears in 16 months when the SST of the tropical western Pacific and the Indian Oceans lag back the Antarctic ice area.
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Acidic species, such as Nitrate, in polar snow and firn layers are "reversibly" deposited, and are sufficiently volatile to undergo significant post-deposi-tional exchange between snow/firn and the atmosphere. Through comparison of the snow pit and snow pack nitrate concentrations from central East Antarctica and the headwater of Urumqi River, we conclude that the nitrate peaks in the uppermost surface snow layers in central Antarctica are not related to an atmospheric signal and must account for post-deposit ional effects. Such effects, however, are not found in the surface snowpack nitrate profiles from the headwater of Urumqi River. Two reasons may account for the post-deposit ional difference. At first, nitrate in the polar snow and firn layers appears to be hydrated ion, which can be taken up by the atmosphere, while at the headwater of Urumqi River it seems mainly as mineral ion, which assembles the behavior of aerosol-derived species that are irreversibly deposited and do not undergo significant post-deposit ional exchange with the atmosphere. Secondly, the chemical features of the snow and ice on the Antarctica are mainly determined by wet deposition, to the contrary, dry deposition is more significant at the headwater of Urumqi River than that on the East Antarctic Plateau.
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Based on the data obtained from tens of the investigated soil profiles scattered over the Fildes Peninsula, King George Island, the maritime Antarctic, the soilforming processes were discussed. It was concluded that on the weathering crusts resulted from various physical courses, the strong freeze-thaw action within regolith, significant organic matter accumulation, evident leaching and illuviation, as well as initial argillification dominated the formation and development of the soils on the Fildes Peninsula. Furthermore, this study indicated that the juvenility of genesis, poor profile-expression, variation in column thickness, etc. characterized the pedogenetic features of the soils of the Fildes Peninsula.
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The radioactive isotope 137Cs is one of the important tracers for studying the physical processes and the human impacts on the environment. Based on the investigation results of the terrestrial ecosystem of Great Wall Station, Antarctica, it was shown that there are some artificial radioactive elements 137Cs in Antarctic terrestrial ecosystem. The sequence of 137Cs specific activities is as follows: crustaceous lichen > fruticose licnen> surface-moss> surface soil, and the crustaceous lichen is one of the most sensitive ways in monitoring the impact of the long-term diffusion of 137Cs on the environment.
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During the Austral summer of 1996/ 1997, the First Chinese Antarctic Inland Expedition reached the inland area about 330 km along the direction around 76°E from Zhongshan Station, and collected 84 surface snow samples at an interval of 4 km. Micro-particle analysis of the samples indicates that the micro-particle concentration apparently decreases with the increasing of altitude, and the amplitudes of micro-particle concentration is much larger in the lower altitude than in the higher altitude. Further analysis of grain-size distributions of micro-particle, percentage of micro-particles from different sources and variations with altitude suggest that micro-particles in this area are from a considerably dominant source. Although this area is controlled by polar easterly wind and katabatic wind, transportation and deposition of the micro-particles are mainly influenced by marine transportation in coastal area.
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A new technique of eigen mode analysis, Method of Natural Orthogonal Components (MNOC) is used to analyze the ionospheric equivalent current systems obtained on the basis of magnetic data at six meridian magnetometer chains in the northern hemisphere during March 17-19, 1978. The results show that the whole current pattern for any given instant consists of a few eigen modes with different intensities. The first eigen mode exhibits a two-eell current construction, characterizing the large-scale magnetospheric convection and directly driven process, while the second eigen mode shows a concentrated westward electrojet at midnight sector, characterizing the substorm current wedge and the loading-unloading process. The first mode consistently exists whenever during quiet periods or at substorms, and its intensity increases from the beginning of the growth phase of substorms, then quickly intensifies in the expansion phase, followed by a gradual decrease in the recovery phase. On the other hand, the intensity of the second mode remains to be near zero during both quiet time and the growth phase of substorms. Its rapid enhancement occurs in the expansion phase. These characteristics in the current patterns and the intensity variations coincide with the defined physical processes of the directly driven and loading-unloading components.
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The Sqp equivalent current system of the quiet day geomagnetic variation in the polar region is very complicated. It is composed of several currents, such as the ionospheric dynamo current and the auroral electrojet caused by the field-aligned current.Sqp is unsymmetrical in both polar regions. In this paper, the Sqp current systems are analyzed in the corrected geomagnetic coordinates (CGM) instead of the conventional geomagnetic coordinates (GM), and the symmetries of the Sqp current in different systems are compared. Then the causes of Sqp asymmetry in the CM coordinates are discussed; the effects of each component in Sqp are determined.
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Digital filter technology is an important method in study of geomagnetic pulsations in Antarctica. The signals received by pulsation magnetometer on the ground include various types of magnetic pulsations. Some types of pulsations or some frequency bands of pulsations can be extracted from the signals by means of digital filter technology because types of pulsations are defined according to their frequency range. In this paper usual digital filter technology is provided for study of magnetic pulsations in Antarctica and some examples are introduced.
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Based on the general framework of ADDS (Antarctic Data Directory System) established by SCAR-COMNAP ad hoc Planning Group on Antarctic data management, the CN-ADDS (Chinese Antarctic Data Directory System) project is going on, of which the research and activity keeps to the available method and technique in ADDS development and allows for the Chinese specific status in Antarctic data management as well. At present, authoring and submitting timely Antarctic data directory in China is one of the key issues that is to be dealt with necessarily. This paper aims at studying the technical procedure in collecting, processing, examining and submitting data directory. In additional, it also discusses the efficient collection of data directory, which needs the effort of administrative and technical support.
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