极地研究

Select

Structure and seasonal changes in atmospheric boundary layer on coast of the east Antarctic continent

BIAN Lingen, ZOU Han, LIN Zhong, ZHANG Dongqi, Annette Rinke & Klaus Dethloff

2013, 24 (3-English): 139-146. DOI: 10.3724/SP.J.1085.2013.00139

摘要 ( 940 )

PDF(2066KB) ( 906 )

The temperature, humidity, and vertical distribution of ozone in the Antarctic atmospheric boundary layer(ABL) and their seasonal changes are analyzed, by using the high-resolution profile data obtained during the International Polar Year 2008 to 2009 at Zhongshan Station, to further the understanding of the structure and processes of the ABL. The results show that the frequency of the convective boundary layer in the warm season accounts for 84% of its annual occurrence frequency. The frequency of the stable boundary layer in the cold season accounts for 71% of its annual occurrence frequency. A neutral boundary layer appears rarely. The average altitude of the convective boundary layer determined by the parcel method is 600 m; this is 200 to 300 m higher than that over inland Antarctica. The average altitude of the top of the boundary layer determined by the potential temperature gradient and humidity gradient is 1 200 m in the warm season and 1 500 m in the cold season. The vertical structures of ozone and specific humidity in the ABL exhibit obvious seasonal changes. The specific humidity is very high with greater vertical gradient in the warm season and very low with a lesser gradient in the cold season under 2 000 m. The atmospheric ozone in the ABL is consumed by photochemical processes in the warm season, which results in a slight difference in altitude. The sub-highest ozone center is located in the boundary layer, indicating that the ozone transferred from the stratosphere to the troposphere reaches the low boundary layer during October and November in Antarctica.

相关文章 | 计量指标

Select

Evaluation of reanalysis and satellite-based sea surface winds using in situ measurements from Chinese Antarctic Expeditions

LI Ming, YANG Qinghua, ZHAO Jiechen, ZHANG Lin, LI Chunhua & MENG Shang

2013, 24 (3-English): 147-152. DOI: 10.3724/SP.J.1085.2013.00147

摘要 ( 908 )

PDF(10687KB) ( 963 )

Sea surface winds from reanalysis (NCEP-2 and ERA-40 datasets) and satellite-based products (QuikSCAT and NCDC blended sea winds) are evaluated using in situ ship measurements from the Chinese National Antarctic Research Expeditions (CHINAREs) from 1989 through 2006, with emphasis on the Southern Ocean (south of 45°S). Compared with ship observations, the reanalysis winds have a positive mean bias (0.32 m?s-1 for NCEP-2 and 0.13 m?s-1 for ERA-40), and this bias is more pronounced in the Southern Ocean (0.57 m?s-1 and 0.45 m?s-1, respectively). However, mean biases are negative in the tropics and subtropics. The satellite-based winds also show positive mean biases, larger than those of the reanalysis data. All four wind products overestimate ship wind speed for weak winds (<4 m?s-1) but underestimate for strong winds (>10 m?s-1). Differences between the reanalysis and satellite winds are examined to identify regions with large discrepancies.

相关文章 | 计量指标

Select

Concentrations and distribution of biogenic barium in surface sediments of Prydz Bay, Antarctica

TAN Saizhang, YU Peisong, HU Chuanyu, HAN Zhengbing & ZHANG Haisheng

2013, 24 (3-English): 153-157. DOI: 10.3724/SP.J.1085.2013.00153

摘要 ( 951 )

PDF(674KB) ( 983 )

Concentrations of biogenic barium were investigated in surface sediments of Prydz Bay, Antarctica, during the 21st and 27th CHINARE cruises. Factors controlling the observed distribution are explored. Biogenic barium concentrations obtained from a sequential extraction procedure are compared with total concentrations obtained from the normative calculation based on a total digestion, and differences in the results are examined. Concentrations of biogenic barium, calculated by the normative calculation, were much higher than the concentrations obtained through sequential extraction; this discrepancy is the result of the occurrence of barium associated with Mn/Fe oxides, which represents an important component of total barium in these sediments. Concentrations of biogenic barium obtained from the sequential extraction range from 104 to 445 μg?g-1, and the average concentration was 227 μg?g-1. The highest concentrations of biogenic barium occur in the central area of the bay, where the seawater is more stable, while lower values occur in the bank and the ice shelf. Biogenic barium is significantly linearly correlated with biogenic barium and organic carbon, and similar in distribution of Chl a, which may indicate that primary productivity of phytoplankton in the surface water column is the main environmental factor regulating barium concentration and distribution.

相关文章 | 计量指标

Select

Scale and scope of maritime cargoes through the Arctic Passages

ZHANG Xia, SHOU Jianmin & ZHOU Haojie

2013, 24 (3-English): 158-166. DOI: 10.3724/SP.J.1085.2013.00158

摘要 ( 1029 )

PDF(9078KB) ( 914 )

This paper investigates the sources of goods being shipped through the Arctic passages, and trade generated in the Arctic, including oil and gas exploitation. Furthermore, it assesses the present situation for maritime cargo shipped from the Far East to Northwestern Europe and North America. Two main types of cargo are predicted to pass through the Arctic passages in the future. First, about 10 million t of liquefied natural gas will be delivered from Russia and the Nordic Arctic to the Far East by 2030. Second, there will be two-way trade flow of containerized cargo from the Far East to Europe and the United States through the Northeast, Central and Northwest Passages. This will relieve pressure on present routes from the Far East to Northwestern Europe and North America. If Arctic navigation is technically possible in all seasons and shipping costs fall to those of ordinary ships, then assuming an equal share of shipping volume with the traditional canal routes, the maximum container freight passing through the Arctic passages by 2030 will be approximately 17.43 million TEUs (Twenty-foot Equivalent Units) per year, which is 85% of the volume transported on traditional canal routes in 2011. We conclude that there will be large-scale gas transportation through the Northeast Passage in the near future, and transit shipping across the Arctic will focus more on container transportation. The differences in shipping costs between Arctic routes and traditional canal routes are also compared.

相关文章 | 计量指标

Select

Composition and distribution of diatom assemblages in the surface sediments of the Bering Sea

SHAO Lixia, LIN Rongcheng, GAO Yahui & HUANG Dingyong

2013, 24 (3-English): 167-174. DOI: 10.3724/SP.J.1085.2013.00167

摘要 ( 941 )

PDF(12429KB) ( 825 )

Diatoms collected from the top 1 cm of the surface sediment layer at seven Bering Sea stations during the Fourth Chinese National Arctic Research Expedition (4th CHINARE-Arctic) in 2010 were studied. In total, 101 taxa belonging to 38 genera were found. The species were divided into four groups: eurythermal species, boreal-temperate species, polar species, and sea-ice species. The diatom assemblages at the stations in the southwestern basin area were primarily composed of boreal-temperate species, such as Neodenticula seminae, Thalassiosira trifulta, Rhizosolenia hebetata f. hiemalis, and Actinocyclus curvatulus. The northeastern shelf stations were dominated by polar species, including Fragilariopsis oceanica, Thalassiosira antarctica spora, Thalassiosira nordenskioeldii, and Thalassiosira hyalina. The overall abundance was highest at the basin stations with 3.7 ×106 cells?g-1 of wet sediment, whereas the eastern shelf stations had the lowest abundance of 0.7×106 cells?g-1 of wet sediment (excluding the resting spores of Chaetoceros spp.). The relationship between the distribution of the surface sediment diatom assemblages and the environment is discussed.

相关文章 | 计量指标

Select

Auroral event detection using spatiotemporal statistics of local motion vectors

WANG Qian, LIANG Jimin & HU Zejun

2013, 24 (3-English): 175-182. DOI: 10.3724/SP.J.1085.2013.00175

摘要 ( 842 )

PDF(25291KB) ( 688 )

The analysis and exploration of auroral dynamics are very significant for studying auroral mechanisms. This paper proposes a method based on auroral dynamic processes for detecting auroral events automatically. We first obtained the motion fields using the multiscale fluid flow estimator. Then, the auroral video frame sequence was represented by the spatiotemporal statistics of local motion vectors. Finally, automatic auroral event detection was achieved. The experimental results show that our methods could detect the required auroral events effectively and accurately, and that the detections were independent on any specific auroral event. The proposed method makes it feasible to statistically analyze a large number of continuous observations based on the auroral dynamic process.

相关文章 | 计量指标

Select

A new method to determine the tropopause

HAN Tingting, PING Jinsong, ZHANG Sujun & YANG Guogen

2013, 24 (3-English): 183-187. DOI: 10.3724/SP.J.1085.2013.00183

摘要 ( 972 )

PDF(2414KB) ( 1005 )

The tropopause has a complex structure and some interference information may exist in high-resolution global positioning system (GPS)/low earth-orbiting (LEO) radio occultation (RO) data. The position of the tropopause cannot be accurately determined using traditional cold point tropopause (CPT) and lapse rate tropopause (LRT) algorithms. In this paper, an integrative algorithm is developed to determinate tropopause parameters. The algorithm is applied to GPS/COSMIC RO data to obtain a global distribution of the height and temperature of the tropopause. This algorithm improves the utilization rate of GPS/LEO RO data by 30% compared with that from the traditional CPT method. The rationality and reliability of GPS/LEO RO data in probing the Earth’s atmosphere are verified by our study of the tropopause using COSMIC data.

相关文章 | 计量指标

Select

Features of visibility variation at Great Wall Station, Antarctica

YANG Qinghua, YU Lejiang, WEI Lixin, ZHANG Benzheng & MENG Shang

2013, 24 (3-English): 188-193. DOI: 10.3724/SP.J.1085.2013.00188

摘要 ( 1063 )

PDF(6306KB) ( 831 )

The variation of visibility at Great Wall Station (GWS) was analyzed using manual observational data for the period of 1986 to 2012. Results show that the frequencies of occurrence of high (≥10 km) and low visibility (0―1 km) are 61.0% and 8.0%, respectively. Visibility at GWS shows an evident seasonal variation: The highest visibility between November and March, and the lowest visibility from June to October. Sea fog and precipitation are the main factors for low visibility during summer, whereas frequent adverse weather, such as falling snow, blowing snow, or blizzards, are responsible for low visibility in winter. The frequency of occurrence of low visibility has decreased significantly from 1986 to 2012. Conversely, the frequency of occurrence of high visibility has shown a significant increasing trend, especially during winter. The decreasing tendencies of fog, blowing snow, and snowfall have contributed to the increasing trend of high visibility during winter. Visibility at GWS exhibits significant synoptic-scale (2.1 to 8.3 d), annual, and inter-annual periods (2 a, 4.1 a, and 6.9 a to 8.2 a), among which the most significant period is 4.1 a. The visibility observed during 2012 indicates that instrumental observation can be applied in the continuous monitoring of visibility at GWS.

相关文章 | 计量指标

过刊目录