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91.
Airborne measurements of the emissions from natural fires, fueled by pyrites and organic materials, at the Smoking Hills in the Northwest Territories, show that they are a regionally significant source of SO2 (0.3 kg s–1 or 104 T yr–1) and particles (0.3 kg s–1). It appears likely that the Smoking Hills are a source for some of the dense, lower-level, haze layers that occur in the North American Arctic. 相似文献
92.
Systematic variability occurs between the oxygen isotopic composition of lake water sampled in mid-summer 1993 and cellulose extracted from surficial sediments of a suite of lakes spanning the forest-tundra transition near Noril'sk, Russia. Some tundra and all forest-tundra lakes show greater deviation from expected cellulose-water isotopic separation than forest lakes, apparently because of greater sensitivity to 18O-depleted snowmelt contributions. Cellulose derived from aquatic plants naturally integrates fluctuations in lake water 18O, providing a signal that is inherently more representative of average thaw season lake water 18O than the measure of instantaneous 18O obtained from an individual sample of lake water. Thus, indiscriminate use of empirical cellulose-water relations derived from calibration samples could lead to erroneous assessment of paleohydrology from the oxygen-isotope stratigraphy of sediment cores from arctic lakes. However, deviation from the expected cellulose-water fractionation is a source of lake-specific hydrologic information useful for qualifying paleoenvironmental interpretations and possibly constraining non-isotopic methods that rely on surface-sediment calibrations. 相似文献
93.
《世界地质(英文版)》2016,(4):241-254
The Arctic hosts an extraordinary wealth of terrestrial fossil biotas of Late Cretaceous age representing a diverse and highly productive near-polar ecosystem that has no modern analogue. Compared to the rest of the Late Cretaceous Maastrichtian plant diversity was at its lowest and the temperature regime the coolest,yet the semi-open forests supported a rich dinosaur fauna made up of a wide range of body sizes and feeding strategies.The combination of mild winter temperatures and continuous darkness lasting several months imposed severe constraints on primary productivity. Plant survival strategies involved almost universal winter loss of foliage,which in turn limited food supply for non-migratory overwintering herbivorous animals. A combination of leaf form and tree ring studies has been used to quantify year round variations in temperature and determine the timing of spring bud-break and autumnal leaf fall. While Maastrichtian winter temperatures were cold enough( down to- 10℃ for brief intervals) for frequent frosts and snowfall,summer temperatures were cool but highly variable and at ~ 83 ° N along the north Alaskan coast frequently fell below + 10 ℃. Theropod egg shell fragments at ~ 76 ° N in the Maastrichtian of Northeastern Russia may indicate that dinosaur reproduction took place in the Arctic ecosystem,as distinct from taking place at lower latitude breeding grounds reached by migration.This raises the question of nest management and specifically the maintenance of incubation temperatures,and the duration of incubation. Of critical importance to year-round residency is the timing of hatching and juvenile care before winter darkness set in,temperatures fell to near freezing and food resources became limited. 相似文献
94.
THE EFFECTS OF THE ARCTIC SEA ICE ON THE VARIATIONS OF ATMOSPHERIC GENERAL CIRCULATION AND CLIMATE 总被引:1,自引:0,他引:1 下载免费PDF全文
The SST anomaly of the central-eastern equatorial Pacific and the arctic sea ice anomalies of the four districts lo-cated respectively in 160°E—110°W,110°W—20°W,70°E—160°E and 20°W—70°E are taken as five separate factors.And the relationship between each factor and the atmospheric general circulation and the climate is investigated byobservational analysis and numerical experiments.It is shown that the effects of the arctic sea ice anomalies on the varia-tions of atmospheric circulation and climate are comparable to or even in some cases greater than that of EI Ninoevents.So one should pay much attention to the study of polar sea ice anomalies in climate research. 相似文献
95.
Filtering technique, extended empirical orthogonal function (EEOF), spectrum distribution function and correla-tion analysis have been employed to study the relationship between arctic ice cover (AIC) and monthly mean tempera-ture and precipitation in China. The function of power spectrum density shows that not only a semi-annual and an an-nual oscillation but also a quasi-biennial oscillation can be found in AIC area index series, especially in June, Septemberand November. During the period of analysis, it can also be found that there exists a good correlation between the ElNino events and the AIC area index. An analysis on the EEOF of AIC and the temperature over China exhibits somesignificant temporal-spatial patterns and a better time-lag interrelationship between them. The results from the correla-tion analysis indicate that the variation of AIC area has a significant influence on the temperature and precipitation insubsequent months over China. In addition, it experiences a quasi-biennial low-frequency oscillation and displays tocertain extent some features of propagation. 相似文献
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采用复经验正交函数方法对我国干旱半干旱区45个代表站,近40年来的月降水距平场划分出3种主要的分布型,分析了它们的分布特征,同时还揭示了北极海冰状况与干旱半干旱区夏季降水的密切关系,并初步分析了海冰与极涡,西太平洋副热带高压等大气环流的关联,以了解其可能的天气学影响过程。 相似文献
99.
Heather M. Throckmorton Brent D. Newman Jeffrey M. Heikoop George B. Perkins Xiahong Feng David E. Graham Daniel O'Malley Velimir V. Vesselinov Jessica Young Stan D. Wullschleger Cathy J. Wilson 《水文研究》2016,30(26):4972-4986
Climate change and thawing permafrost in the Arctic will significantly alter landscape hydro‐geomorphology and the distribution of soil moisture, which will have cascading effects on climate feedbacks (CO2 and CH4) and plant and microbial communities. Fundamental processes critical to predicting active layer hydrology are not well understood. This study applied water stable isotope techniques (δ2H and δ18O) to infer sources and mixing of active layer waters in a polygonal tundra landscape in Barrow, Alaska (USA), in August and September of 2012. Results suggested that winter precipitation did not contribute substantially to surface waters or subsurface active layer pore waters measured in August and September. Summer rain was the main source of water to the active layer, with seasonal ice melt contributing to deeper pore waters later in the season. Surface water evaporation was evident in August from a characteristic isotopic fractionation slope (δ2H vs δ18O). Freeze‐out isotopic fractionation effects in frozen active layer samples and textural permafrost were indistinguishable from evaporation fractionation, emphasizing the importance of considering the most likely processes in water isotope studies, in systems where both evaporation and freeze‐out occur in close proximity. The fractionation observed in frozen active layer ice was not observed in liquid active layer pore waters. Such a discrepancy between frozen and liquid active layer samples suggests mixing of meltwater, likely due to slow melting of seasonal ice. This research provides insight into fundamental processes relating to sources and mixing of active layer waters, which should be considered in process‐based fine‐scale and intermediate‐scale hydrologic models. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
100.
在我国对南北极的科学考察中,取得了大量环境与资源考察数据,如何综合管理这些宝贵数据是一项复杂的工程。如果不加以妥善保管,随着时间的推移,有分散和流失的可能;如果不加以开发利用,无法体现极地科学考察的成果和意义。极地空间数据库管理系统是对南北极科学考察获取的空间数据进行综合管理和展示,为南北极科学考察航行、陆地活动、设施管理、(建站、设站、路线等)规划、科学研究和辅助决策提供有力的支持。 相似文献