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30 March 2008, Volume 20 Issue 1 Previous Issue    Next Issue
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STRUCTURE OF A SUBSURFACE EDDY IN CANADIAN BASIN OF ARCTIC OCEAN 2008, 20 (1):  1-13.  Abstract ( 1541 )   PDF (836KB) ( 1627 )   An Arctic Ocean eddy in subsurface layer is analyzed in this paper with temperature, salinity and current profile data obtained at an ice camp in the Canada Basin during the second Chinese Arctic Expedition in summer of 2003. In the vertical temperature section, the eddy shows itself as an isolated cold water block at depth of 60 m with a minimum temperature of -1.5°C that is ~0.5°C colder than the ambient water. Isopycnals in the eddy form a pattern of convex, which indicates the eddy is anticyclonic. Although maximum velocity near 0.4 ms-1 occurs in the current records observed synchronously, the current pattern is far away from a typical eddy. By further analysis, inertial frequency oscillations with amplitudes comparable with the eddy velocity are found in the subsurface layer currents. After removing the inertial current and mean current, an axisymmetric current pattern of an eddy with maximum velocity radius of 5 km is obtained. The analysis of the T-S characteristics of the eddy core water and its ambient waters supports the conclusion that the eddy was formed on the Chukchi Shelf and migrated northeastward into the northern Canada Basin. Related Articles | Metrics

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THE ANTARCTIC CIRCUMPOLAR CURRENT DERIVED FROM THE SATELLITE GRAVITY GEOID AND ALTIMETRY DATA 2008, 20 (1):  14-22.  Abstract ( 1783 )   PDF (784KB) ( 1862 )   Combining a new geoid model (EIGEN-GL04S) recovered from GRACE mission and the KMSS04 model, a new mean dynamic ocean topography (MDT) model are estimated over the Antarctic region. The surface Antarctic Circumpolar Current (ACC) field and its Polar Front (PF) and sub-Antarctic Front (SAF) are derived from MDT after filtering with a wavelet denoising method. Comparing the MDT, surface ACC, PF and SAF with those from previous geoid model (EGM96)/altimetry, merged MDT and the ocean hydrological data (WOA01), separately, the results show that the ACC from GRACE agree well with WOA01 map in general, and reveal more details than all other results. These indicate that the accuracy of EIGEN-GL04S model has been improved greatly over pre-existing models at long wavelengths and the ACC detected by satellite measurement has reached relatively high precision at large and middle scale. Related Articles | Metrics

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ICE CREVASSE DETECTION BASED ON GRAY LEVEL CO-OCCURRENCE MATRIX 2008, 20 (1):  23-35.  Abstract ( 1296 )   PDF (552KB) ( 1411 )   Crevasse is one of the most dangerous factors to the team members during the field expedition. Crevasse detection is very important in polar scientific research expedition for the safety; meanwhile, it is also meaningful information for ice flow monitoring. This paper presents the preliminary study on ice crevasse texture analysis and recognition based on SPOT image of Grove Mountains, east Antarctica. And gray level co-occurrence matrix is chosen at first to recognize the crevasse texture. Combined with the navigation route, the results are analyzed. More texture analysis methods will be studied in optical and radar imagery in further research. References | Related Articles | Metrics

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COMPARATIVE STUDY OF WINTER POLAR IONOSPHERIC F2 LAYER IN BOTH HEMISPHERES 2008, 20 (1):  31-39.  Abstract ( 1658 )   PDF (550KB) ( 1521 )   Diurnal variations of ionospheric F2 layer at Zhongshan (Jun.) and Tromso (Dec.) in winter are comparatively studied by analyzing the data from DSP-4 in 1996, 1997, 1998 and 2002. Combining the results of the numerical simulation, we analyzed the main physical processes which are responsible for the F region ionosphere over Zhongshan and Tromso. The results show that, although both Zhongshan and Tromso have similar geographic latitudes, the mechanisms of the foF2 diurnal variation are not always the same. As a result of the strong interaction between sunlit ionization and horizontal convection, the major peak in the diurnal variation of foF2 at Zhongshan appears around geomagnetic local noon, while the F region at Tromso is less influenced by the horizontal convection on the dayside, making the major peak in the foF2 diurnal variation at about local noon. The foF2 diurmal variations at the both stations are greatly influenced by solar radiation flux, and the auroral particle precipitation has a notable influence on the foF2 diurnal variation at Zhongshan station in solar minimum. Related Articles | Metrics

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DISTRIBUTION OF GAB IN SEDIMENT CORES COLLECTED FROM THE CANADIAN BASIN AND THE CHUKCHI SEA 2008, 20 (1):  40-47.  Abstract ( 1693 )   PDF (527KB) ( 1608 )   The occurrence percentage and content of General Aerobic Heterotrophic Bacteria (GAB)were determined by using the method of MPN for 182 subsamples from 10 sediment cores taken from Canadian basin and Chukchi sea at two different culturing temperatures. The results showed that the general occurrence percentage of GAB was quite high, average contents of GAB at cultured temperatures of 4 ℃ and 25 ℃ were 4.46×107 and 5.47×107 cells·g (wt)-1 respectively. The highest GAB content occurred at 20—22 cm layer in the sediment. GAB contents waved among the strata of sediments, but a trend appeared that: contents in the middle or lower strata were lower than those of upper stratum. Cultivation at 25 ℃ could improve the occurrence percentage and contents of GAB, which suggests that the increasing of temperature may change the living circumstances and conditions of GAB. The differences of GAB among the latitudes areas indicated that occurrence percentage and contents of GAB in middle latitude areas were higher than those in the higher or lower latitude areas, and were more obvious at 4 ℃ than those at 25 ℃. The GAB contents in sediment under the shallower water seemed to be lower than those in sediments under the deeper water and this status was more obvious at 25 ℃ than that at 4 ℃. Related Articles | Metrics

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REVIEW OF THE STATUS, FEATURE AND PROSPECT OF ANTARCTIC SPECIALLY PROTECTED AREAS 2008, 20 (1):  48-63.  Abstract ( 1264 )   PDF (954KB) ( 2020 )   The development of Antarctic specially protected areas(ASPAs), the process and requirement of the drafting, reviewing and ratifying the management plan for the ASPAs are reviewed briefly with reference to the related ATCMs documents. Sixty seven ASPAs have already been designated by Antarctic treaty consultative parties, with the total area of 2700 km2. And these ASPAs are proposed by 13 Antarctic Treaty Consultative Parties, mainly including America,United Kingdom, New Zealand, Australia and Chile. 1996 and 1985 are the peak years for the designation of ASPAs. In the majority of these ASPAs, Antarctic fauna and flora and their habitants, colonies or ecological systems are protected with their great scientific research values. Besides, the status and prospect of ASPAs are analyzed. And the China's first proposed Antarctic specially protected area in Mount Harding, the Grove mountains and its draft of management plan are introduced. Related Articles | Metrics

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ADVANCE IN MICROBIAL DEGRADATION OF POLLUTANT AND BIOREMEDIATION IN POLAR REGIONS 2008, 20 (1):  64-71.  Abstract ( 1601 )   PDF (629KB) ( 2594 )   null Related Articles | Metrics

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ANALYSIS AND FORECASTING OF THE COLD AIR ACTIVITIES IN WINTER AT GREAT WALL STATION,ANTARCTICA 2008, 20 (1):  72-78.  Abstract ( 1420 )   PDF (449KB) ( 1497 )   null Related Articles | Metrics