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1.
北极地区不同冰龄的海冰厚度变化研究 总被引：1，自引：0，他引：1
In this study, changes in Arctic sea ice thickness for each ice age category were examined based on satellite observations and modelled results. Interannual changes obtained from Ice, Cloud, and Land Elevation Satellite(ICESat)-based results show a thickness reduction over perennial sea ice(ice that survives at least one melt season with an age of no less than 2 year) up to approximately 0.5–1.0 m and 0.6–0.8 m(depending on ice age) during the investigated winter and autumn ICESat periods, respectively. Pan-Arctic Ice Ocean Modeling and Assimilation System(PIOMAS)-based results provide a view of a continued thickness reduction over the past four decades. Compared to 1980 s, there is a clear thickness drop of roughly 0.50 m in 2010 s for perennial ice. This overall decrease in sea ice thickness can be in part attributed to the amplified warming climate in north latitudes. Besides, we figure out that strongly anomalous southerly summer surface winds may play an important role in prompting the thickness decline in perennial ice zone through transporting heat deposited in open water(primarily via albedo feedback) in Eurasian sector deep into a broader sea ice regime in central Arctic Ocean. This heat source is responsible for enhanced ice bottom melting, leading to further reduction in ice thickness. 相似文献
2.
2018年北极太平洋区域夏季海冰物理及光学性质的研究 总被引：2，自引：1，他引：1
The reduction in Arctic sea ice in summer has been reported to have a significant impact on the global climate. In this study, Arctic sea ice/snow at the end of the melting season in 2018 was investigated during CHINARE-2018, in terms of its temperature, salinity, density and textural structure, the snow density, water content and albedo, as well as morphology and albedo of the refreezing melt pond. The interior melting of sea ice caused a strong stratification of temperature, salinity and density. The temperature of sea ice ranged from –0.8℃ to 0℃, and exhibited linear cooling with depth. The average salinity and density of sea ice were approximately 1.3 psu and 825 kg/m~3, respectively, and increased slightly with depth. The first-year sea ice was dominated by columnar grained ice. Snow cover over all the investigated floes was in the melt phase, and the average water content and density were 0.74% and 241 kg/m~3, respectively. The thickness of the thin ice lid ranged from 2.2 cm to 7.0 cm, and the depth of the pond ranged from 1.8 cm to 26.8 cm. The integrated albedo of the refreezing melt pond was in the range of 0.28–0.57. Because of the thin ice lid, the albedo of the melt pond improved to twice as high as that of the mature melt pond. These results provide a reference for the current state of Arctic sea ice and the mechanism of its reduction. 相似文献
3.
1Introduction ThephysicalcharacteristicsintheArcticOcean includewidecontinentalshelves,accountingfor36% oftheocean’ssurfacearea(MooreandSmith,1986) withseasonalicecover.Theprincipalwatersentering theArcticOceanarefromtheNorthAtlanticviathe FramStraitandtheBarentsSea,andtheNorthPacific viatheBeringStrait.Withinthearcticinterior,thewa- tersjoininthelarge-scalecirculationandaresubse- quentlymodifiedbyprocessesofair/sea/iceinterac- tion,riverinflow,andexchangewithsurrounding shelves.Howeve… 相似文献
4.
海冰对北极海冰边缘区大洋光学观测的影响评估 总被引：1，自引：1，他引：0
Diffuse attenuation coefficient(DAC) of sea water is an important parameter in ocean thermodynamics and biology, reflecting the absorption capability of sea water in different layers. In the Arctic Ocean, however, sea ice affects the radiance/irradiance measurements of upper ocean, which results in obvious errors in the DAC calculation. To better understand the impacts of sea ice on the ocean optics observations, a series of in situ experiments were carried out in the summer of 2009 in the southern Beaufort Sea. Observational results show that the profiles of spectral diffuse attenuation coefficients of seawater near ice cover within upper surface of 50 m were not contaminated by the sea ice with a solar zenith angle of 55°, relative azimuth angle of 110°≤φ≤115° and horizontal distance between the sensors and ice edge of greater than 25 m. Based on geometric optics theory, the impact of ice cover could be avoided by adjusting the relative solar azimuth angle in a particular distance between the instrument and ice. Under an overcast sky, ice cover being 25 m away from sensors did not affect the profiles of spectral DACs within the upper 50 m either. Moreover, reliable spectral DACs of seawater could be obtained with sensors completely covered by sea ice. 相似文献
5.
Global warming has caused Arctic sea ice to rapidly retreat,which is affecting phytoplankton,the primary producers at the base of the food chain,as well as the entire ecosystem.However,few studies with large spatial scales related to the Arctic Basin at high latitude have been conducted.This study aimed to investigate the relationship between changes in phytoplankton community structure and ice conditions.Fifty surface and 41 vertically stratified water samples from the western Arctic Ocean(67.0°–88°26′N,152°–178°54′W) were collected by the Chinese icebreaker R/V Xuelong from July 20 to August 30,2010 during China's fourth Arctic expedition.Using these samples,the species composition,spatial distribution,and regional disparities of phytoplankton during different stages of ice melt were assessed.A total of 157 phytoplankton taxa(5 μm) belonging to 69 genera were identified in the study area.The most abundant species were Navicula pelagica and Thalassiosira nordenskioeldii,accounting for 31.23% and 14.12% of the total phytoplankton abundance,respectively.The average abundance during the departure trip and the return trip were 797.07×10~2 cells/L and 84.94×10~2 cells/L,respectively.The highest abundance was observed at Sta.R09 in the north of Herald Shoal,where Navicula pelagica was the dominant species accounting for 59.42% of the abundance.The vertical distribution of phytoplankton abundance displayed regional differences,and the maximum abundances were confined to the lower layers of the euphotic zone near the layers of the halocline,thermocline,and nutricline.The species abundance of phytoplankton decreased from the low-latitude shelf to the high-latitude basin on both the departure and return trips.The phytoplankton community structure in the shallow continental shelf changed markedly during different stages of ice melt,and there was shift in dominant species from centric to pennate diatoms.Results of canonical correspondence analysis(CCA) showed that there were two distinct communities of phytoplankton in the western Arctic Ocean,and water temperature,ice coverage and silicate concentration were the most important environmental factors affecting phytoplankton distribution in the surveyed sea.These findings will help predict the responses of phytoplankton to the rapid melting of Arctic sea ice. 相似文献
6.
基于CryoSat-2数据的2010-2017年北极海冰厚度和体积的季节与年际变化特征 总被引：2，自引：2，他引：0
北极海冰变化影响着全球物质平衡、能量交换和气候变化。本文基于CryoSat-2测高数据和OSI SAF海冰密集度及海冰类型产品，分析了2010-2017年北极海冰面积、厚度和体积的季节和年际变化特征，结合NCEP再分析资料探讨了融冰期北极气温异常和夏季风异常对海冰变化的影响。结果表明，结冰期海冰面积的增加量波动较大，海冰厚度的增加量呈明显下降趋势。融冰期海冰厚度的减小量波动较大，2013年以后融冰期海冰面积的减小量逐年增加。海冰体积的变化趋势和面积变化更相似，融冰期的减小速率大于结冰期的增加速率。融冰期北极海表面大气温度异常与海冰融化量正相关。夏季风影响海冰的辐合和辐散，在弗拉姆海峡海冰的输运过程中起关键作用，促进了北冰洋表层水向大洋深层的传输。 相似文献
7.
8.
The vertical structure of the atmospheric boundary layer over the central Arctic Ocean 总被引：2，自引：1，他引：1
The tropopause height and the atmospheric boundarylayer （PBL） height as well as the variation of inversion layer above the floating ice surface are presented using GPS （global position system ） radiosonde sounding data and relevant data obtained by Chinas fourth arctic scientific expedition team over the central Arctic Ocean （86°-88°N, 144°-170°W） during the summer of 2010. The tropopause height is from 9.8 to 10.5 km, with a temperature range between -52.2 and -54.10C in the central Arctic Ocean. Two zones of maximum wind （over 12 m/s） are found in the wind profile, namely, low- and upper-level jets, located in the middle troposphere and the tropopause, respectively. The wind direction has a marked variation point in the two jets from the southeast to the southwest. The average PBL height determined by two methods is 341 and 453 m respectively. These two methods can both be used when the inversion layer is very low, but the results vary significantly when the inversion layer is very high. A significant logarithmic relationship exists between the PBL height and the inversion intensity, with a correlation coefficient of 0.66, indicating that the more intense the temperature inversion is, the lower the boundary layer will be. The observation results obviously differ from those of the third arctic expedition zone （800-85° N）. The PBL height and the inversion layer thickness are much lower than those at 870-88° N, but the inversion temperature is more intense, meaning a strong ice- atmosphere interaction in the sea near the North Pole. The PBL structure is related to the weather system and the sea ice concentration, which affects the observation station. 相似文献
9.
《Ocean Modelling》2001,3(1-2):127-135
The high-latitude freezing and melting cycle can variously result in haline convection, freshwater capping or freshwater injection into the interior ocean. An example of the latter process is a secondary salinity minimum near 800 m-depth within the Arctic Ocean that results from the transformation on the Barents Sea shelf of Atlantic water from the Norwegian Sea and its subsequent intrusion into the Arctic Ocean. About one-third of the freshening on the shelf of that initially saline water appears to result from ice melt, although the actual sea ice flux is small, only about 0.005 Sv. A curious feature of this process is that water distilled at the surface of the Arctic Ocean by freezing ends up at mid-depth in the same ocean. This is a consequence of the ice being exported southward onto the shelf, melted, and then entrained into the northward Barents Sea throughflow that subsequently sinks into the Arctic Ocean. Prolonged reduction in sea ice in the region and in the concomitant freshwater injection would likely result in a warmer and more saline interior Arctic Ocean below 800 m. 相似文献
10.
Fresh water flowing from the Arctic Ocean via the East Greenland Current influences deep water formation in the Nordic Seas as well as the salinity of the surface and deep waters flowing from there. This fresh water has three sources: Pacific water (relatively fresh cf. Atlantic water), river runoff, and sea ice meltwater. To determine the relative amounts of the three sources of fresh water, in May 2002 we collected water samples across the East Greenland Current in sections from 81.5°N to the Irminger Sea south of Denmark Strait. We used nitrate-phosphate relationships to distinguish Pacific waters from Atlantic waters, salinity to obtain the sum of sea ice melt water and river runoff water, and total alkalinity to distinguish the latter. River runoff contributed the largest part of the total fresh water component, in some regions with some inventories exceeding 12 m. Pacific fresh water (Pacific source water S ∼ 32 cf. Atlantic source water S ∼ 34.9) typically provided about 1/3 of the river runoff contribution. Sea ice meltwater was very nearly non-existent in the surface waters of all sections, likely at least in part as a result of the samples being collected before the onset of the melt season. The fresh water from the Arctic Ocean was strongly confined to near the Greenland coast. We thus conjecture that the main source of fresh water from the Arctic Ocean most strongly impacting deep convection in the Nordic Seas would be sea ice as opposed to fresh water in the liquid phase, i.e., river runoff, Pacific fresh water, and sea ice meltwater. 相似文献
11.
Eiji Watanabe Michio J. Kishi Akio Ishida Maki Noguchi Aita 《Journal of Oceanography》2012,68(5):703-718
The response of phytoplankton to the Beaufort shelf-break eddies in the western Arctic Ocean is examined using the eddy-resolving coupled sea ice–ocean model including a lower-trophic marine ecosystem formulation. The regional model driven by the reanalysis 2003 atmospheric forcing from March to November captures the major spatial and temporal features of phytoplankton bloom following summertime sea ice retreat in the shallow Chukchi shelf and Barrow Canyon. The shelf-break warm eddies spawned north of the Barrow Canyon initially transport the Chukchi shelf water with high primary productivity toward the Canada Basin interior. In the eddy-developing period, the anti-cyclonic rotational flow along the outer edge of each eddy moving offshore occasionally traps the shelf water. The primary production inside the warm eddies is maintained by internal dynamics in the eddy-maturity period. In particular, the surface central area of an anti-cyclonic eddy acquires adequate light, nutrient, and warm environment for photosynthetic activity partly attributed to turbulent mixing with underlying nutrient-rich water. The simulated biogeochemical properties with the dominance of small-size phytoplankton inside the warm eddies are consistent with the observational findings in the western Arctic Ocean. It is also suggested that the light limitation before autumn sea ice freezing shuts down the primary production in the shelf-break eddies in spite of nutrient recovery. These results indicate that the time lag between the phytoplankton bloom in the shelf region following the summertime sea ice retreat and the eddy generation along the Beaufort shelf break is an important index to determine biological regimes in the Canada Basin. 相似文献
12.
1Introduction Seaiceoccupiesthemainpartofthesurfaceof theArcticOcean.ThefocusoftheSecondChineseNa- tionalArcticResearchExpedition(CHINAE-2003) wastounderstandthevariationsofarcticmarineenvi- ronmentsandtheseaiceeffectsontheclimatechanges ofglobalextent,inmiddleandlowerlatitudesareas, especiallyinChina.Therefore,thejointsea-ice-airob- servationforseaicestudieswasoneofthekeypro- jectsinCHINARE-2003.Theinvestigatedareacov- ered3000kmfromsouthtonorthand900kmfrom westtoeast.Seventemporali… 相似文献
13.
Arctic salinity anomalies and their link to the North Atlantic during a positive phase of the Arctic Oscillation 总被引：1，自引：0，他引：1
Marie-Noelle Houssais Christophe Herbaut Clément Rousset 《Progress in Oceanography》2007,73(2):160-189
Many of the changes observed during the last two decades in the Arctic Ocean and adjacent seas have been linked to the concomitant abrupt decrease of the sea level pressure in the central Arctic at the end of the 1980s. The decrease was associated with a shift of the Arctic Oscillation (AO) to a positive phase, which persisted throughout the mid 1990s. The Arctic salinity distribution is expected to respond to these dramatic changes via modifications in the ocean circulation and in the fresh water storage and transport by sea ice. The present study investigates these different contributions in the context of idealized ice-ocean experiments forced by atmospheric surface wind-stress or temperature anomalies representative of a positive AO index.Wind stress anomalies representative of a positive AO index generate a decrease of the fresh water content of the upper Arctic Ocean, which is mainly concentrated in the eastern Arctic with almost no compensation from the western Arctic. Sea ice contributes to about two-third of this salinification, another third being provided by an increased supply of salt by the Atlantic inflow and increased fresh water export through the Canadian Archipelago and Fram Strait. The signature of a saltier Atlantic Current in the Norwegian Sea is not found further north in both the Barents Sea and the Fram Strait branches of the Atlantic inflow where instead a widespread freshening is observed. The latter is the result of import of fresh anomalies from the subpolar North Atlantic through the Iceland-Scotland Passage and enhanced advection of low salinity waters via the East Icelandic Current. The volume of ice exported through Fram Strait increases by 20% primarily due to thicker ice advected into the strait from the northern Greenland sector, the increase of ice drift velocities having comparatively less influence. The export anomaly is comparable to those observed during events of Great Salinity Anomalies and induces substantial freshening in the Greenland Sea, which in turn contributes to increasing the fresh water export to the North Atlantic via Denmark Strait. With a fresh water export anomaly of 7 mSv, the latter is the main fresh water supplier to the subpolar North Atlantic, the Canadian Archipelago contributing to 4.4 mSv.The removal of fresh water by sea ice under a positive winter AO index mainly occurs through enhanced thin ice growth in the eastern Arctic. Winter SAT anomalies have little impact on the thermodynamic sea ice response, which is rather dictated by wind driven ice deformation changes. The global sea ice mass balance of the western Arctic indicates almost no net sea ice melt due to competing seasonal thermodynamic processes. The surface freshening and likely enhanced sea ice melt observed in the western Arctic during the 1990s should therefore be attributed to extra-winter atmospheric effects, such as the noticeable recent spring-summer warming in the Canada-Alaska sector, or to other modes of atmospheric circulations than the AO, especially in relation to the North Pacific variability. 相似文献
14.
A one-dimensional thermodynamic model of melt pond is established in this paper.The observation data measured in the summer of 2010 by the Chinese National Arctic Research Expedition(CHINARE-2010) are used to partially parameterize equations and to validate results of the model.About 85% of the incident solar radiation passed through the melt pond surface,and some of it was released in the form of sensible and latent heat.However,the released energy was very little(about 15%),compared to the incident solar radiation.More than 58.6% of the incident energy was absorbed by melt pond water,which caused pond-covered ice melting and variation of pond water temperature.The simulated temperature of melt pond had a diurnal variation and its value ranged between 0.0°C and 0.3°C.The melting rate of upper pond-covered ice is estimated to be around two times faster than snow-covered ice.At same time,the change of melting rate was relatively quick for pond depth less than 0.4 m,while the melting rate kept relatively constant(about 1.0 cm/d) for pond depth greater than 0.4 m. 相似文献
15.
Sea-ice physical characteristics were investigated in the Arctic section of 143°-180°W during August and early September 2008. Ship-based observations show that both the sea-ice thickness and concentration recorded during southward navigation from 30 August to 6 September were remarkably less than those recorded during northward navigation from 3 to 30 August, especially at low latitudes. Accordingly, the marginal ice zone moved from about 74.0°N to about 79.5°N from mid-August to early September. Melt-pond coverage increased with increasing latitude, peaking at 84.4°N, where about 27% of ice was covered by melt ponds. Above this latitude, melt-pond coverage decreased evidently as the ice at high latitudes experienced a relatively short melt season and commenced its growth stage by the end of August. Regional mean ice thickness increased from 0.8 (±0.5) m at 75.0°N to 1.5 (±0.4) m at 85.0°N along the northward navigation while it decreased rapidly to 0.6 (±0.3) m at 78.0°N along the southward navigation. Because of relatively low ice concentration and thin ice in the investigated Arctic sector, both the short-term ice stations and ice camp could only be set up over multiyear sea ice. Observations of ice properties based on ice cores collected at the short-term ice stations and the ice camp show that all investigated floes were essentially isothermal with high temperature and porosity, and low density and salinity. Most ices had salinity below 2 and mean density of 800-860 kg/m~3 . Significant ice loss in the investigated Arctic sector during the last 15 a can be identified by comparison with the previous observations. 相似文献
16.
Comparison of airsea fluxes of CO2 in the Southern Ocean and the western Arctic Ocean 总被引：1，自引：0，他引：1
The data were collected during Chinese Arctic and Antarctic Expeditions in the western Arctic Ocean and the marginal sea ice zone (MSIZ) of the Southern Ocean, respectively in the boreal summer from July to September of 1999 and in the austral summer from December of 1999 to January of 2000. The concentrations of CO2 in surface water of the survey regions would mostly present lower than those in the atmosphere. A significant biological driving force could also been observed in summer waters in both of the above oceans. Air to sea CO2 fluxes were also calculated to compare oceanic uptake capacity of CO2 in both oceans with the world oceans using Liss, Wanninkhof, and Jacobs‘s methods. The averaged CO2 fluxes of air to sea in the western Arctic Ocean or in the MSIZ of the Southern Ocean doubled that in the world oceans. 相似文献
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18.
For ocean and climate research, it is essential to get long-term altimetric sea level data that is as accurate as possible. However, the accuracy of the altimetric data is frequently degraded in the interior of the Arctic Ocean due to the presence of seasonal or permanent sea ice. We have reprocessed ERS-1/2/Envisat satellite altimetry to develop an improved 20-year sea level dataset for the Arctic Ocean. We have developed both an along-track dataset and three-day gridded sea level anomaly (SLA) maps from September 1992 to April 2012. A major improvement in data coverage was gained by tailoring the standard altimetric editing criteria to Arctic conditions. The new reprocessed data has significant increased data coverage with between 4 and 10 times the amount of data in regions such as the Beaufort Gyre region compared with AVISO and RADS datasets. This allows for a more accurate estimation of sea level changes from satellite altimetry in the Arctic Ocean. The reprocessed dataset exhibit a mean sea level trend of 2.1 ± 1.3 mm/year (without Glacial Isostatic Adjustment correction) covering the Arctic Ocean between 66°N and 82°N with significant higher spatial coherency in the ice-covered regions than the RADS and DUACS datasets. 相似文献
19.
A coupled ice-ocean model is configured for the pan-Arctic and northern North Atlantic Ocean with a 27.5 km resolution. The model is driven by the daily atmospheric climatology averaged from the 40-year NCEP reanalysis (1958–1997). The ocean model is the Princeton Ocean Model (POM), while the sea ice model is based on a full thermodynamical and dynamical model with plastic-viscous rheology. A sea ice model with multiple categories of thickness is utilized. A systematic model-data comparison was conducted. This model reasonably reproduces seasonal cycles of both the sea ice and the ocean. Climatological sea ice areas derived from historical data are used to validate the ice model performance. The simulated sea ice cover reaches a maximum of 14 × 106 km2 in winter and a minimum of 6.7 × 106 km2 in summer. This is close to the 95-year climatology with a maximum of 13.3 × 106 km2 in winter and a minimum of 7 × 106 km2 in summer. The simulated general circulation in the Arctic Ocean, the GIN (Greenland, Iceland, and Norwegian) seas, and northern North Atlantic Ocean are qualitatively consistent with historical mapping. It is found that the low winter salinity or freshwater in the Canada Basin tends to converge due to the strong anticyclonic atmospheric circulation that drives the anticyclonic ocean surface current, while low summer salinity or freshwater tends to spread inside the Arctic and exports out of the Arctic due to the relaxing wind field. It is also found that the warm, saline Atlantic Water has little seasonal variation, based on both simulation and observations. Seasonal cycles of temperature and salinity at several representative locations reveals regional features that characterize different water mass properties. 相似文献
20.
Ho Jung Song Jae Hyung Lee Gawn Woo Kim So Hyun Ahn Houng-Min Joo Jin Young Jeong Eun Jin Yang Sung-Ho Kang Sang Heon Lee 《Ocean Science Journal》2016,51(3):387-396
Recent changes in climate and environmental conditions have had great negative effects such as decreasing sea ice thickness and the extent of Arctic sea ice floes that support ice-related organisms. However, limited field observations hinder the understanding of the impacts of the current changes in the previously ice-covered regions on sea ice algae and other ice-related ecosystems. Our main objective in this study was to measure recent primary production of ice algae and their relative contribution to total primary production (ice plus pelagic primary production). In-situ primary productivity experiments with a new incubation system for ice algae were conducted in 3 sea ice cores at 2 different ice camps in the northern Chukchi Sea, 2014, using a 13C and 15N isotope tracer technique. A new incubation system was tested for conducting primary productivity experiments on ice algae that has several advantages over previous incubation methods, enabling stable carbon and nitrogen uptake experiments on ice algae under more natural environmental conditions. The vertical C-shaped distributions of the ice algal chl-a, with elevated concentrations at the top and bottom of the sea ice were observed in all cores, which is unusual for Arctic sea ice. The mean chl-a concentration (0.05 ± 0.03 mg chl-a m?3) and the daily carbon uptake rates (ranging from 0.55 to 2.23 mg C m?2 d?1) for the ice algae were much lower in this study than in previous studies in the Arctic Ocean. This is likely because of the late sampling periods and thus the substantial melting occurring. Ice algae contributed 1.5–5.7% of the total particulate organic carbon (POC) contents of the combined euphotic water columns and sea ice floes. In comparison, ice algae contributed 4.8–8.6% to the total primary production which is greater than previously reported in the Arctic Ocean. If all of the ice-associated productions were included, the contributions of the sea ice floes to the total primary production would be greater in the Arctic Ocean and their importance would be greater in the arctic marine ecosystems. 相似文献