极地研究

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Interaction between sea ice/iceberg and ship structures: A review

JI Shunying & LIU Shewen

2012, 23 (4-English): 187-195. DOI: 10.3724/SP.J.1085.2012.00187

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For ship structural design and good maneuverability in an ice-covered sea, the local and global load of ice cover on ships should be well understood. This paper reviews the extensive work done on ice loads on ships, including: (a) Ice pressure and local load determination based on field and model tests; (b) Global ice loads on ships from full-scale field observations, model tests and numerical models under different ice conditions (level ice and pack ice) and ship operations (maneuvering and mooring). Special attention is paid to the discrete element simulation of global ice loads on ships; and (c) Analytical solutions and numerical models of impact loads of icebergs on ships for polar navigation. Finally, research potential in these areas is discussed.

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Validation of total ozone data between satellite and ground-based measurements at Zhongshan and Syowa stations in Antarctica

BIAN Lingen, LIN Zhong, ZHANG Dongqi, ZHENG Xiangdong & LU Longhua

2012, 23 (4-English): 196-203. DOI: 10.3724/SP.J.1085.2012.00196

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We present validation between total ozone from satellite and ground-based observations of the Dobson and Brewer spectrometers and ozone radiosonde at Zhongshan and Syowa Antarctic research stations, for September 2004 to March 2009. Results show that mean bias error between Zhongshan (Syowa) and Ozone Monitor Instrument Total Ozone Mapping Spectrometer (OMI-TOMS) data are −0.06%±3.32% (−0.44%±2.41%); between it and OMI Multi Axis Differential Optical Absorption Spectroscopy (OMI-DOAS) data, the error is −0.34%±4.99% (−0.22%±4.85%). Mean absolute bias error values of OMI-TOMS data are less than those of OMI-DOAS. This means that total ozone of OMI-TOMS is closer to ground-based observation than that of OMI-DOAS. Comparison between direct observational total ozone of ground-based and integrated ozone from the ozone profile measured by ozone radiosonde shows that ozone amount calculated with the Solar Backscatter Ultraviolet (SBUV) method above balloon burst height is similar to corresponding Microwave Limb Sounder (MLS) data. Therefore, MLS data can be substituted with SBUV data to estimate ozone amount above that level. Mean bias error of the MLS ozone column is 2% compared with the ozonesonde column, with standard deviation within 9.5%. Comparison of different layers from ozone profiler and MLS data indicates that at the 215 hPa layer, the MLS ozone value is high, with relative deviation more than 20%. At the 100 hPa and 68 hPa layers, the MLS ozone value is also high. This deviation is mainly in spring, during Antarctic ozone hole appearance. In this period, at the height of severe ozone loss, relative deviation of MLS ozone values is especially large.

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Simultaneous optical and radar observations of poleward moving auroral forms under different IMF conditions

XING Zanyang, YANG Huigen, HAN Desheng, WU Zhensen, LIU Junming, HU Zejun,et al.

2012, 23 (4-English): 204-210. DOI: 10.3724/SP.J.1085.2012.00204

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Using high temporal resolution optical data obtained from three-wavelength all-sky imagers at Chinese Yellow River Station in the Arctic, together with the EISCAT Svalbard radar (ESR) and SuperDARN radars, we investigated the dayside poleward moving auroral forms (PMAFs) and the associated plasma features in the polar ionosphere under different interplanetary magnetic field (IMF) conditions, between 0900 and 1010 UT on 22 December 2003. Simultaneous optical and ESR observations revealed that all PMAFs were clearly associated with pulsed particle precipitations. During northward IMF, particles can precipitate into lower altitudes and reach the ionospheric E-region, and there is a reverse convection cell associated with these PMAFs. This cell is one of the typical signatures of the dayside high-latitude (lobe) reconnection in the polar ionosphere. These results indicate that the PMAFs were associated with the high-latitude reconnection. During southward IMF, the PMAFs show larger latitudinal motion, indicating a longer mean lifetime, and the associated ionospheric features indicate that the PMAFs were generated by the dayside low-latitude reconnection.

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The distribution and concentration of particulate biogenic silica in surface waters of Prydz Bay, Antarctica, during the austral summer of 2011

HU Chuanyu, SHEN Chen & ZHANG Haisheng

2012, 23 (4-English): 211-216. DOI: 10.3724/SP.J.1085.2012.00211

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The concentrations and distributions of particulate biogenic silica (PBSi) in the upper surface waters of Prydz Bay, Antarctica, were investigated during the 27th Chinese National Antarctic Research Expedition cruises of January 2011. We aimed to characterize the correlations between PBSi and plankton, nutrients and particulate organic carbon. The results showed that the concentrations of biogenic silica ranged from 0.76—19.72 μmol?dm-3 and the average concentration of biogenic silica was 6.06 μmol?dm-3. The distribution of surface PBSi had significant regional characteristics: The concentrations were higher south of 67°S than to the north. The distribution of PBSi, chlorophyll a and particulate organic carbon showed similar patterns, and PBSi distribution had a negative correlation with that of silicate. In the vertical direction, the mole ratio of PBSi and POC (Sibio/Corg) decreased with increasing depth. This trend indicated a higher rate of PBSi dissolution, or a lower rate of organic matter remineralization rate, in the upper 200 m.

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Influence of sea ice and sea surface temperature on the abundance of Antarctic krill in Area 48.2

DAI Lifeng, ZHANG Shengmao & FAN Wei

2012, 23 (4-English): 217-224. DOI: 10.3724/SP.J.1085.2012.00217

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In this paper we examine the relationship between Antarctic krill catch, sea ice concentration, and sea surface temperature (SST). Data on the Antarctic krill catch from 2003 to 2010 in CCAMLR Area 48.2 were combined with sea ice and SST data. Results showed that krill fishing in Area 48.2 took place from February to August each year but the catch was concentrated from March to July, with production during this period accounting for about 99.3% of the annual catch. Regression analysis showed that the catch per unit effort (CPUE) was clearly related to sea ice concentration and SST intervals. CPUE was negatively correlated with the area of sea ice among years (R2=0.64), and the correlation was strongest (R2=0.71) when sea ice concentration was greater than 90%. Over the months the CPUE initially increased, then decreased as the area of sea ice increased. The relationship was strongest (R2=0.88) when the concentration of sea ice was 60%—70%. There was no negative correlation among years between CPUE and the ice-free area when SST was between -2℃and 3℃ (R2=0.21), but there was a significant negative correlation when SST was between 1℃ and 2℃ (R2=0.82). Over the months, CPUE initially increased then decreased with increasing sea ice-free area, and the relationship was strongest (R2=0.94) when SST was between 0℃ and 1℃. This study shows that sea ice concentration and SST have significant effects on the abundance of krill in Area 48.2, and the findings have practical significance for the use and conservation of Antarctic krill resources.

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Phytoplankton community changes indicated by biomarker from sediment in Prydz Bay, Antarctica

YU Peisong, ZHANG Haisheng, HU Chuanyu & LU Bing

2012, 23 (4-English): 225-230. DOI: 10.3724/SP.J.1085.2012.00225

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Biomarkers including brassicasterol, dinosterol and alkenone in sediments are used as indicators to reconstruct changes to the phytoplankton community in surface and sub-aerial sediments of Prydz Bay, Antarctica. The results indicate that the biomarker records in surface and core sediment samples changed with time and space. The total content of phytoplankton biomarkers ranges from 391.0—1 470.6 ng?g-1. The phytoplankton biomass has increased in Prydz Bay over the past 100 years. This variation may be mainly related with climate change in the region. The total biomarker contents in surface sediments from 5 stations in Prydz Bay are in the range of 215.8—1 294.3 ng?g-1. The phytoplankton biomass in Prydz Bay is higher than that outside of the bay. This is similar to the distributions of chlorophyll a, organic carbon and biogenic silica in surface waters determined through in situ investigation. Such consistency indicates a coupling between the bottom of the ocean and biogeochemical processes in the upper water.

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Organic carbon deposition flux on the North Chukchi Sea shelf based on ²¹⁰Pb radioactivity dating

LI Yiliang, YU Wen, HE Jianhua & SU Jian

2012, 23 (4-English): 231-236. DOI: 10.3724/SP.J.1085.2012.00231

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Deposition of organic carbon forms the final net effect of the ocean carbon sink at a certain time scale. Organic carbon deposition on the Arctic shelves plays a particularly important role in the global carbon cycle because of the broad shelf area and rich nutrient concentration. To determine the organic carbon deposition flux at the northern margin of the Chukchi Sea shelf, the ²¹⁰Pb dating method was used to analyze the age and deposition rate of sediment samples from station R17 of the third Chinese National Arctic Research Expedition. The results showed that the deposition rate was 0.6 mm?a-1, the apparent deposition mass flux was 0.72 kg?m-2?a-1, and the organic carbon deposition flux was 517 mmol C?m-2?a-1. It was estimated that at least 16% of the export organic carbon flux out of the euphotic zone was transferred and chronically buried into the sediment, a value which was much higher than the average ratio (~10%) for low- to mid-latitude regions, indicating a highly effective carbon sink at the northern margin of the Chukchi Sea shelf. With the decrease of sea ice coverage caused by warming in the Arctic Ocean, it could be inferred that the Arctic shelves will play an increasingly important role in the global carbon cycle.

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Spatial distribution of pico- and nano-phytoplankton and bacteria in the Chukchi Sea in relation to water masses

ZHANG Fang, HE Jianfeng, LIN Ling, LIU Ying, WANG Xiaoying & DING Chen

2012, 23 (4-English): 237-243. DOI: 10.3724/SP.J.1085.2012.00237

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We evaluated the relationships between water masses and pico- and nano-phytoplankton and bacterial abundance in the Chukchi Sea. The abundance of picoplankton ranged from 0.01 × 103 cells?mL-1 (100 m, station R05) to 2.21 × 103 cells?mL-1 (10 m, station R05) and that of nanoplankton ranged from 0.03 × 103 cells?mL-1 (100 m, station R07) to 2.21 × 104 cells?mL-1 (10 m, station R05). The lowest abundance of bacteria in the whole water column (0.21 × 106 cells?mL-1) was at 100 m at station R17, and the highest (9.61 × 106 cells?mL-1) was at 10 m at station R09. Melting sea ice affected the physical characteristics of the Chukchi Sea by reducing salinity of the surface mixed layer, resulting in greater hydrodynamic stability of the water column. These changes were accompanied by increased bacterial abundance. The warm Pacific water brought nutrients into the Chukchi Sea, resulting in greater abundance of bacteria and nano-phytoplankton in the Chukchi Sea than in other regions of the Arctic Ocean. However, the abundance of pico-phytoplankton, which was related to chlorophyll a concentration, was higher in Anadyr water than in the other two water masses. The structures of pico- and nanoplankton communities coupled with the water masses in the Chukchi Sea can serve as indicators of the inflow of warm Pacific water into the Chukchi Sea.

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Call for papers for a special issue of AFoPS Meeting 2012

2012, 23 (4-English): 244.

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Dear Colleagues,
    This is a call for papers for a special issue of the journal Advances in Polar Science (APS) focused on “AFoPS Meeting 2012”. We hope that you might consider submitting a paper to this special issue, and we encourage you to share this announcement broadly with interested colleagues.
    The special issue is focused on AFoPS Meeting 2012, which was held in Delhi, India in August of 2012. This issue will provide a forum summarizing recent advances on Asian polar expeditions and researches during 2012 or earlier years.
    Sincerely,
    Prof. Huigen Yang, Guest Editor in Chief

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