Abstract (
)
Download PDF (
)
Knowledge map
Save
Abstract (
)
Download PDF (
)
Knowledge map
Save
Abstract (
)
Download PDF (
)
Knowledge map
Save
Terrigenous components in sediment core B84A from the Alpha Ridge, Western Arctic Ocean, have been investigated to reconstruct Mid to Late Quaternary variations in sedimentation, provenance, and related climate changes. The core stratigraphy, evaluated by a combination of variations in Mn content, color cycles, foraminiferal abundance, and lithological correlation, extends back to estimated Marine Isotope Stage 12. Twelve Ice Rafted Detritus (IRD, >250 μm) events were identifld and interpreted to mostly occur during deglaciation. The Canadian Arctic, which was covered by ice sheets during glacial periods, is suggested to be the major source region. The IRD events likely indicate the collapses of ice sheets, possibly in response to abrupt climate changes. Grain size analysis of B84A indicates sedimentologically sensitive components in core B84A in the 4-9 μm and 19-53 μm silt subfractions, which are inferred to be mainly transported by currents and sea ice, respectively. Down core variability of these two fractions may indicate changes in ice drift and current strength. In accordance with previous studies in the central Arctic Ocean, the average sedimentation rate in core B84A is about 0.4 cm•a-1. Compared with the relatively high sedimentation rates on the margins, sedimentation in the central Arctic Ocean is limited by sea ice cover and the correspondingly low bioproductivity, as well as the long distance from source regions of terrigenous sediment.
Abstract (
)
Download PDF (
)
Knowledge map
Save
Conductivity, temperature and depth (CTD) data from 1993-2010 are used to study water temperature in the upper Canada Basin. There are four kinds of water temperature structures: The remains of the winter convective mixed layer, the near-surface temperature maximum (NSTM), the wind-driven mixed layer, and the advected water under sea ice. The NSTM mainly appears within the conductive mixed layer that forms in winter. Solar heating and surface cooling are two basic factors in the formation of the NSTM. The NSTM can also appear in undisturbed open water, as long as there is surface cooling. Water in open water areas may advect beneath the sea ice. The overlying sea ice cools the surface of the advected water, and a temperature maximum could appear similar to the NSTM. The NSTM mostly occurred at depths 10-30 m because of its deepening and strengthening during summer, with highest frequency at 20 m. Two clear stages of interannual variation are identified. Before 2003, most NS TMs were observed in marginal ice zones and open waters, so temperature maxima were usually warmer than 0℃ After 2004, most NSTMs occurred in ice-covered areas, with much colder temperature maxima. Average depths of the temperature maxima in most years were about 20 m, except for about 16 m in 2007, which was related to the extreme minimum of ice cover. Average temperatures were around –0.8℃ to –1.1℃, but increased to around –0.5℃ in 2004, 2007 and 2009, corresponding to reduced sea ice. As a no-ice summer in the Arctic is expected, the NSTM will be warmer with sea ice decline. Most energy absorbed by seawater has been transported to sea ice and the atmosphere. The heat near the NSTM is only the remains of total absorption, and the energy stored in the NSTM is not considerable. However, the NSTM is an important sign of the increasing absorption of solar energy in seawater.
Abstract (
)
Download PDF (
)
Knowledge map
Save
Conductivity, temperature, and depth data collected during the summers of 2003 and 2008 were used to study upper-ocean (top 200 m) heat content in the Canada Basin. The variation of heat content with depth, heat content diFFErences between the summers, principal driving factors, and horizontal spatial scale diFFErences were analyzed. A catastrophic reduction of sea ice cover in the Canada Basin was evident in 2008 by comparison with 2003, suggesting that more solar radiation was absorbed in the upper ocean during the summer of 2008. The sea ice reduction produced more freshwater in the upper ocean. Thus, seawater properties changed. The study shows that the huge reduction of sea ice would result in two changes-widespread warming of the upper ocean, and the depth of pacific inflow water in the basin increased substantially. Near-surface temperature maximum (NSTM) water was also analyzed as an indicator of Arctic Ocean warming.
Abstract (
)
Download PDF (
)
Knowledge map
Save
The third Chinese National Arctic Research Expedition (3rd CHINARE-Arctic in 2008) was carried out from July to September 2008. During the survey, numerous sea water samples were taken for CO2 parameter measurement (including total alkalinity TA and total dissolved inorganic carbon DIC).The distribution of CO2 parameters in the Western Arctic Ocean was determined, and the controlling factors are addressed. The ranges of summertime TA, normalized TA (nTA), DIC and normalized DIC (nDIC) in the surface seawater were 1 757-2 229 μmol·kg-1, 2 383-2 722 μmol·kg-1, 1 681-2 034 μmol·kg-1, 2 119-2 600 μmol·kg-1, respectively. Because of dilution from ice meltwater, the surface TA and DIC concentrations were relatively low. TA in the upper 100 m to the south of 78°N had good correlation with salinity, showing a conservative behavior. The distribution followed the seawater-river mixing line at salinity >30, then followed the seawater mixing line (diluted by river water to salinity = 30) with the ice meltwater. The DIC distribution in the Chukchi Sea was dominated by biological production or respiration of organic matter, whereas conservative mixing dominated the mixed layer TA distribution in the ice-free Canada Basin.
Abstract (
)
Download PDF (
)
Knowledge map
Save
This paper presents aerosol black carbon (BC) concentrations measured at deck level on board the R/V
Abstract (
)
Download PDF (
)
Knowledge map
Save
Tropospheric ozone (O3), ultraviolet B (UVB) radiation and aerosol light scattering coe±cients (SC) were investigated on a cruise ship during the fourth Chinese National Arctic Research Expedition from July 1September 20, 2010. The results showed that O3, UVB and SC decreased with increasing latitude, with minimum values recorded in the central Arctic Ocean. Average O3 concentrations were 15.9 ppbv and 15.1 ppbv in the Bering Sea and Arctic Ocean, respectively. Ozone concentrations increased to 17.5 ppbv in the high Arctic region. Average UVB values were 0.26 W·m-2 and 0.14 W·m-2 in the Bering Sea and Arctic Ocean, respectively. The average SC in the Bering Sea was 4.3 M·m?1, more than twice the value measured in the Arctic Ocean, which had an average value of 1.7 M·m-1. Overall, UVB and SC values were stable in the central Arctic Ocean.
Abstract (
)
Download PDF (
)
Knowledge map
Save
During the fourth Chinese National Arctic Research Expedition cruise in summer 2010, a time-series
observation was carried out to examine the response of nutrients and phytoplankton community in the ice-water
interface to the ice melting ice in the central Arctic Ocean. Phosphate and silicate in the ice-water interface were
rich relative to dissolved inorganic nitrogen (DIN), based on the Redfield ratio (16N:1P:16Si), suggesting that DIN
was the potential limiting nutrient. DIN concentrations in the sea ice were about 3-4 times that in the surface
seawater, indicating that melting ice delivered DIN to the surface water. Pigment analysis showed that fucoxanthin
and chlorophyll
Abstract (
)
Download PDF (
)
Knowledge map
Save
Accelerated decline of summer and winter Arctic sea ice has been demonstrated progressively. Melt ponds play a key role in enhancing the feedback of solar radiation in the ice/ocean-atmosphere system, and have thus been a focus of researchers and modelers. A new melt pond investigation system was designed to determine morphologic and hydrologic features, and their evolution. This system consists of three major parts: Temperature-salinity measuring, surface morphology monitoring, and water depth monitoring units. The setup was deployed during the ice camp period of the fourth Chinese National Arctic Research Expedition in summer 2010. The evolution of a typical Arctic melt pond was documented in terms of pond depth, shape and surface condition. These datasets are presented to scientifically reveal how involved parameters change, contributing to better understanding of the evolution mechanism of the melt pond. The main advantage of this system is its suitability for autonomous and long-term observation, over and within a melt pond. Further, the setup is portable and robust. It can be easily and quickly installed, which is most valuable for deployment under harsh conditions.
Abstract (
)
Download PDF (
)
Knowledge map
Save
As a part of the National Report of China for the International Association for Physical Science of
Ocean (IAPSO), the main research results of Chinese scientists in Arctic physical oceanography during 2007-2010
are reviewed in this paper. This period overlaps with the International Polar Year (IPY), which is a catalyst for
nations to emphasize activities and research in the polar regions. The Arctic also experienced a rapid change
in sea ice, ocean, and climate during this time. China launched two Arctic cruises with the R/V
沪公网安备 31011502017260号