3月北半球海冰趋势变化的区域特征及影响因子分析

利用海冰密集度资料和海冰范围指数,分析了3月北半球海冰在1979-1995年和1996-2014年2个时间段内的变化趋势以及趋势差异的区域特征.结果表明:北半球3月总海冰范围以稳定速率减少,速率无明显加速.而各个分海域的海冰变化表现出一定的区域差异.其中,巴伦支海海冰在2个时期内以稳定的速率减少;白令海海冰不减反增;鄂霍次克海海冰缩减速度在后期减小;圣劳伦斯湾的海冰范围在90年代中期以前显著增大,后期缓慢缩减. 3月海冰趋势变化的空间特征与同期表面气温和表面风场的趋势变化相一致.     

气候变化下西北太平洋大海洋生态系海表面温度特征分析

气候变化和气候事件对海洋环境有着重大的影响,其影响存在着时空差异。研究以西北太平洋五个大型海洋生态系统(Large Marine Ecosystem,LME,包括西白令海,鄂霍茨克海,黑潮、亲潮以及日本海)的海表面温度(Sea surface temperature,SST)为研究对象,分析SST的随时空变化趋势及其与太平洋年代际振荡((Pacific Decadal Oscillation, PDO)和厄尔尼诺(El Ni?o)、拉尼娜(La Ni?a)事件的影响。研究发现,除了西白令海,其它四个大型海洋生态系统的SST都在1987年左右发生了急剧的上升,呈现出两个变化模态;将SST的长期变化趋势去除后,可以发现,五个LME的SST随着时间上下波动,并没有固定的周期性变化存在,但是与厄尔尼诺拉尼娜事件有着密切联系。水温的空间分布上看,各区域的SST都呈现由北向南逐渐增高的趋势,但是增温趋势不尽相同,在西白令海的整个区域SST都在升高,降温区域围绕在库页岛和日本的北海道附近,这其中相关机制有待后续进一步研究。     

Diatoms and the ecological conditions of their growth in sea ice in the arctic ocean

A summer field survey off Point Barrow, Alaska, revealed that Arctic sea ice develops a growth of phytoplanktonic diatoms. The diatoms are found in a brine solution in microfissures between ice crystals on the underside of the ice. The chlorophyll content of this layer is 100 times more than that of the surrounding sea waters; this has led to a hypothesis that a considerable fraction of the primary production of the Arctic Sea may be carried out in sea ice, especially during the spring and early summer months.     

Primary Production in Antarctic Sea Ice

A numerical model shows that in Antarctic sea ice, increased flooding in regions with thick snow cover enhances primary production in the infiltration (surface) layer. Productivity in the freeboard (sea level) layer is also determined by sea ice porosity, which varies with temperature. Spatial and temporal variation in snow thickness and the proportion of first-year ice thus determine regional differences in sea ice primary production. Model results show that of the 40 teragrams of carbon produced annually in the Antarctic ice pack, 75 percent was associated with first-year ice and nearly 50 percent was produced in the Weddell Sea.     

A 10,000-year record of Arctic Ocean sea-ice variability--view from the beach

We present a sea-ice record from northern Greenland covering the past 10,000 years. Multiyear sea ice reached a minimum between ~8500 and 6000 years ago, when the limit of year-round sea ice at the coast of Greenland was located ~1000 kilometers to the north of its present position. The subsequent increase in multiyear sea ice culminated during the past 2500 years and is linked to an increase in ice export from the western Arctic and higher variability of ice-drift routes. When the ice was at its minimum in northern Greenland, it greatly increased at Ellesmere Island to the west. The lack of uniformity in past sea-ice changes, which is probably related to large-scale atmospheric anomalies such as the Arctic Oscillation, is not well reproduced in models. This needs to be further explored, as it is likely to have an impact on predictions of future sea-ice distribution.     

Massive phytoplankton blooms under Arctic sea ice

Phytoplankton blooms over Arctic Ocean continental shelves are thought to be restricted to waters free of sea ice. Here, we document a massive phytoplankton bloom beneath fully consolidated pack ice far from the ice edge in the Chukchi Sea, where light transmission has increased in recent decades because of thinning ice cover and proliferation of melt ponds. The bloom was characterized by high diatom biomass and rates of growth and primary production. Evidence suggests that under-ice phytoplankton blooms may be more widespread over nutrient-rich Arctic continental shelves and that satellite-based estimates of annual primary production in these waters may be underestimated by up to 10-fold.     

Variability of antarctic sea ice: and changes in carbon dioxide

A definitive long-term decrease in the extent of antarctic sea ice is not detectable from 9 years (1973 to 1981) of year-round satellite observations and limited prior data. Regional interannual variability is large, with sea ice decreasing in some regions while increasing in others. A significant decrease in overall ice extent during the mid-1970's, previously suggested to reflect warming induced by carbon dioxide, has not been maintained. In particular, the extent of ice in the Weddell Sea region has rebounded after a large decrease concurrent with a major oceanographic anomaly, the Weddell polynya. Over the 9 years, the trends are nearly the same in all seasons, but for periods of 3 to 5 years, greater winter ice maxima are associated with lesser summer ice minima. The decrease of the mid-1970's was preceded by an increase in ice extent from 1966 to 1972, further indicating the presence of cyclical components of variation that obscure any long-term trends that might be caused by a warming induced by carbon dioxide.     

1989—2018年南极布兰斯菲尔德海峡海冰时空变化分析

基于1989—2018年美国冰雪中心海冰密集度数据，分析近30年南极布兰斯菲尔德海峡及附近海域海冰分布规律及变化趋势。结果表明，布兰斯菲尔德海峡内部海冰属于1年冰，海冰密集度于2月达到最低，8月达到最高，历史上强厄尔尼诺年份与该区域海冰密集度较低的年份存在明显对应关系。对30年冰情线性拟合得到年际变化趋势，海峡内结冰月份普遍延迟，年结冰月数以减少为主。3个代表站点的海冰密集度分析结果显示，海峡内A站点海冰变化与海峡口外北部海域B站点的相关性较强，与海峡口外南部靠近威德尔海区域C站点的相关性弱。循环神经网络模型可用于预测和分析海冰密集度的时序变化，尤其是适合海冰密集度相对较低的时序分析。     

基于Flex Viewer框架的北冰洋海冰卫星遥感信息系统的设计与实现

北冰洋是世界上最小、最浅和最冷的大洋,位于地球最北端,终年覆盖着海冰,是地球的最大冷源之一。北冰洋的海冰变化在不同的时间尺度上影响着全球的气候变化。卫星遥感技术是海冰监测的有效手段之一。目前为止,国内外相关海冰研究机构已获取了三十多年的海冰数据,这些数据是今后更加深入地开展北冰洋海冰研究的重要依据。针对海量的海冰卫星遥感数据,在Flex Viewer开源框架下,利用互联网应用(rich internet applications,RIA)技术和Web GIS技术,开发了北冰洋海冰卫星遥感信息系统。系统具有GIS功能强大、界面友好、平台无关以及开发效率高、开发成本低等优点,为北冰洋海冰遥感数据采集、查询、空间分析和实时数据服务的网络应用提供了一种很好的解决方案。     

The percolation phase transition in sea Ice

Sea ice exhibits a marked transition in its fluid transport properties at a critical brine volume fraction pc of about 5 percent, or temperature Tc of about -5 degreesC for salinity of 5 parts per thousand. For temperatures warmer than Tc, brine carrying heat and nutrients can move through the ice, whereas for colder temperatures the ice is impermeable. This transition plays a key role in the geophysics, biology, and remote sensing of sea ice. Percolation theory can be used to understand this critical behavior of transport in sea ice. The similarity of sea ice microstructure to compressed powders is used to theoretically predict pc of about 5 percent.     

Paleo-Eskimo mtDNA genome reveals matrilineal discontinuity in Greenland

The Paleo-Eskimo Saqqaq and Independence I cultures, documented from archaeological remains in Northern Canada and Greenland, represent the earliest human expansion into the New World's northern extremes. However, their origin and genetic relationship to later cultures are unknown. We sequenced a mitochondrial genome from a Paleo-Eskimo human by using 3400-to 4500-year-old frozen hair excavated from an early Greenlandic Saqqaq settlement. The sample is distinct from modern Native Americans and Neo-Eskimos, falling within haplogroup D2a1, a group previously observed among modern Aleuts and Siberian Sireniki Yuit. This result suggests that the earliest migrants into the New World's northern extremes derived from populations in the Bering Sea area and were not directly related to Native Americans or the later Neo-Eskimos that replaced them.     

Large yearly production of phytoplankton in the Western bering strait

Production in the western Bering Strait is estimated at 324 grams of carbon per square meter per year over 2.12x 10(4) square kilometers. An ice-reduced growing season makes this large amount of primary production unexpected, but it is consistent with the area's large upper trophic level stocks. The productivity is fueled by a cross-shelf flow of nutrient-rich water from the Bering Sea continental slope. This phytoplankton production system from June through September is analogous to a laboratory continuous culture.     

Freshening of the Ross Sea during the late 20th century

Ocean measurements in the Ross Sea over the past four decades, one of the longest records near Antarctica, reveal marked decreases in shelf water salinity and the surface salinity within the Ross Gyre. These changes have been accompanied by atmospheric warming on Ross Island, ocean warming at depths of approximately 300 meters north of the continental shelf, a more negative Southern Oscillation Index, and thinning of southeast Pacific ice shelves. The freshening appears to have resulted from a combination of factors, including increased precipitation, reduced sea ice production, and increased melting of the West Antarctic Ice Sheet.     

Changes in the west antarctic ice sheet

The portion of the West Antarctic ice sheet that flows into the Ross Sea is thinning in some places and thickening in others. These changes are not caused by any current climatic change, but by the combination of a delayed response to the end of the last global glacial cycle and an internal instability. The near-future impact of the ice sheet on global sea level is largely due to processes internal to the movement of the ice sheet, and not so much to the threat of a possible greenhouse warming. Thus the near-term future of the ice sheet is already determined. However, too little of the ice sheet has been surveyed to predict its overall future behavior.     

Oil and ice in the arctic ocean: possible large-scale interactions

The diffusion and transport mechanisms generated by the pack ice dynamics of the Beaufort Sea, combined with the slow rate of biodegradation of oil under Arctic conditions, would combine to diffuse an oil spill over the sea and eventually deposit the oil on the ice surface, where it would lower the natural albedo over a large area.     

黄海北部仿刺参浮游幼体发生与附着习性的初步研究

于1997－1998年对黄海北部大长山岛自然海区仿刺参（Apostichopus japonicus）浮游幼体的发生与习性进行了研究。用浮游生物拖网在海上定期、定点进行刺参浮游幼体调查，发现浮游幼体出现时间为7月15日－9月31日，幼体高峰出现时间为8月1日，最大资源生物量为70只／m^3。通过检查不同水层刺参浮游幼体的附苗效果，发现3m水层的附苗量最多。另外，通过海上试验和室内试验还对刺参幼体对附着基材料的选择性进行了试验。结果表明，在常用的几种采苗附着基中，幼体对棕绳、聚乙烯网片选择性最好，其次为锚流网衣和波纹板，对贝壳和胶带选择性最差。     

Accelerated sea-level rise from West Antarctica

Recent aircraft and satellite laser altimeter surveys of the Amundsen Sea sector of West Antarctica show that local glaciers are discharging about 250 cubic kilometers of ice per year to the ocean, almost 60% more than is accumulated within their catchment basins. This discharge is sufficient to raise sea level by more than 0.2 millimeters per year. Glacier thinning rates near the coast during 2002-2003 are much larger than those observed during the 1990s. Most of these glaciers flow into floating ice shelves over bedrock up to hundreds of meters deeper than previous estimates, providing exit routes for ice from further inland if ice-sheet collapse is under way.     

黄海北部仿刺参养殖池塘关键环境因子的周年变化与管理研究

研究了黄海北部非投喂型仿刺参Apostichopus japonicus养殖池塘的温度、溶氧、盐度、pH和大型生物等环境因子的周年变化特点,以及春季化冰期池塘的温度、盐度、pH的日变化规律,同时对池塘的纳潮换水、水位管理以及敌害生物的控制等技术环节进行了探讨,分析了环境因子与仿刺参养殖的关系。结果表明：（1）池塘周年水温变化在-1．2～30．4℃,最高在8月,最低在1月;溶解氧值波动于3．5—21．3mg／L,冬季高,夏季低;溶解氧与温度之间的回归关系为Do=0．018T^2-0．818T＋15．805;pH值波动于7．印～8．72,冬、夏季高,春、秋季低;盐度波动于22．5～33．5,夏季偏低。（2）冬季水温下降到-1．0℃时,池塘表层开始结冰并逐渐封冰;春季在化冰时存在温度和盐度跃层,可采用将表层水排放掉的方法消除跃层。（3）池塘的大型植物主要包括缘管浒苔、刚毛藻、沟草等,大型动物主要有矛尾缎虎鱼、石鲽、花鲈、蓝点马鲛、鲮、斑鲦、鳐等鱼类,太平洋牡蛎、菲律宾蛤仔、黑荞麦蛤等贝类以及脊尾白虾、口虾蛄等。（4）在化冰期注意池塘盐度变化,化冰前池塘冰下水位应控制在120～130cm以上,化冰后池塘水深应控制在150—170cm以上。（5）在夏季高温期应注意监测溶解氧的变化,防止因藻类死亡腐败、溶解氧含量下降而导致仿刺参发生缺氧死亡的现象。     

Global sea level and Earth rotation

Recent analyses of long time scale secular variations of sea level, based on tide gauge observations, have established that sea level is apparently rising at a globally averaged rate somewhat in excess of 1 millimeter per year. It has been suggested that the nonsteric component of this secular rate might be explicable in terms of ongoing mass loss from the small ice sheets and glaciers of the world. Satellite laser ranging and very long baseline interferometry data may be used to deliver strong constraints on this important scenario because of the information that these systems provide on variations of the length of day and of the position of the rotation pole with respect to the earth's surface geography. These data demonstrate that the hypothesis of mass loss is plausible if the Barents Sea was covered by a substantial ice sheet at the last maximum of the current ice age 18,000 years ago.     

Synchronous tropical South China Sea SST change and Greenland warming during deglaciation

The tropical ocean plays a major role in global climate. It is therefore crucial to establish the precise phase between tropical and high-latitude climate variability during past abrupt climate events in order to gain insight into the mechanisms of global climate change. Here we present alkenone sea surface temperature (SST) records from the tropical South China Sea that show an abrupt temperature increase of at least 1 degrees C at the end of the last glacial period. Within the recognized dating uncertainties, this SST increase is synchronous with the B?lling warming observed at 14.6 thousand years ago in the Greenland Ice Sheet Project 2 ice core.