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《The Journal of geography》2012,111(3):133-138
Abstract North American Exploration: A Continent Defined, Volume 2, John Logan Allen, editor, Lincoln, Nebraska: University of Nebraska Press. 1997. 480 pp. Illustrations, maps. ISBN 080321023x. $75.00 (Cloth). North American Exploration: A Continent Defined, Volume 3, John Logan Allen, editor, Lincoln, Nebraska: University of Nebraska Press. 1997. 656 pp. Illustrations, maps. ISBN 0803210434. $75.00 (Cloth). Space, Gender, and Knowledge, Linda McDowell and Joanne P. Sharp, editors, New York, NY John Wiley & Sons. 1997. 468 pp. ISBN 0470236698. $34.95 (paper). The Japanese City, P.P. Karan and Kristin Stapleton, editors, Lexington, Kentucky: The University Press of Kentucky. 1997. 264 pp. ISBN 0813120357. $31.95 (cloth). Education, Environment and Economy: Reporting Research in a New Academic Grouping, Frances Slater, David Lambert, and David Lines, editors, London, England: Institute of Education, University of London. 1997. 210 pp. Figures., ISBN 0854734996. £11.99 (paper). The Peopling of Africa: A Geographic Interpretation, James L. Newman New Haven, Connecticut: Yale University Press. 1997., 252 pp. Maps., ISBN 0300072805. $15.00 (paper). 相似文献
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We present the first 3-dimensional self-consistent calculations of the response of Saturn's global thermosphere to different sources of external heating, giving local time and latitudinal changes of temperatures, winds and composition at equinox and solstice. Our calculations confirm the well-known finding that solar EUV heating alone is insufficient to produce Saturn's observed low latitude thermospheric temperatures of 420 K. We therefore carry out a sensitivity study to investigate the thermosphere's response to two additional external sources of energy, (1) auroral Joule heating and (2) empirical wave heating in the lower thermosphere. Solar EUV heating alone produces horizontal temperature variations of below 20 K, which drive horizontal winds of less than 20 m/s and negligible horizontal changes in composition. In contrast, Joule heating produces a strong dynamical response with westward winds comparable to the sound speed on Saturn. Joule heating alone, at a total rate of 9.8 TW, raises polar temperatures to around 1200 K, but values equatorward of 30° latitude, where observations were made, remain below 200 K due to inefficient meridional energy transport in a fast rotating atmosphere. The primarily zonal wind flow driven by strong Coriolis forces implies that energy from high latitudes is transported equatorward mainly by vertical winds through adiabatic processes, and an additional 0.29-0.44 mW/m2 thermal energy are needed at low latitudes to obtain the observed temperature values. Strong upwelling increases the H2 abundances at high latitudes, which in turn affects the H+3 densities. Downwelling at low latitudes helps increase atomic hydrogen abundances there. 相似文献
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Patrick Ludwig Milivoj B. Gavrilov Milica G. Radaković Slobodan B. Marković 《第四纪科学杂志》2021,36(8):1426-1435
We investigate the glacial climate conditions in the southeastern Carpathian Basin (Vojvodina, Serbia) based on the reconstruction of malacological palaeotemperatures and results from a high-resolution regional climate simulation. Land snail assemblages from eight loess profiles are used to reconstruct July temperatures during the Last Glacial Maximum (LGM). The malacological reconstructed temperatures are in good agreement with the simulated LGM July temperatures by the Weather Research and Forecast model. Both methods indicate increasing temperatures from the northwestern towards the southeastern parts of the study area. LGM aridity indices calculated based on the regional climate model data suggest more arid conditions in the southeastern parts compared with more humid conditions in the northwestern parts. However, for present-day conditions, the moisture gradient is reversed, exhibiting more humid (arid) conditions in the southeast (northwest). An explanation for the reversed LGM aridity pattern is provided by an analysis of the prevailing wind directions over the South Banat district (Serbia). The prevailing moist northwesterly winds during summer are not able to compensate for the annual lack of moisture induced by the dry winds from the southeast that are more frequent during the LGM for the other seasons. 相似文献
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温度、光照、氮含量对微绿球藻生长及脂肪酸组成的影响 总被引：21，自引：1，他引：21
报道了环境因子对微结球藻（Nannochloropsis oculata)的生长速率及脂肪酸组成的影响，结果表明：微绿球藻具有较快的生长速度，且富含16：1（n-7)和20：5（n-3)(EPA)。适温范围为0－30℃，最适温度为20℃，温度对脂肪酸组成的影响较明显，EPA在20摄氏度时最高，30℃时急剧下降，生长较适宜光强为5000－7000lx，但在1000lx时EPA产率最大；氮含量为10mg/L时生长速度最快，但此时EPA含量较低。 相似文献
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大型滑坡地下水系统的概念模型以长江三峡库区宝塔滑坡为例 总被引：10，自引：0，他引：10
本文以中国长江三峡工程库区大型滑坡宝塔滑坡为例 ,在地质结构研究的基础上 ,尝试通过地下水动力场、水化学场、水温度场和水的环境同位素的调查研究 ,查清地下水补给、径流、排泄条件和地下水随外界因素 (降雨、水库蓄水和人为入渗、排水等 )变化的规律 ,从而建立滑坡地下水系统的概念模型。这既是滑坡的地下水预测和变形预测的必要基础 ,也为滑坡的治理指明了方向。 相似文献
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基于被动微波辐射传输方程,结合De Jeu建立的透过率与微波极化差异指数的通用关系式,以及Smiths建立的地表温度与大气总可降水量的经验关系,构建了一套基于AMSR-E影像的地表温度半经验反演模型,该模型无需借助其他辅助数据,便可从AMSR-E 6.9GHz和10.7GHz两个波段的亮度温度模拟得到地表温度变量。对2009年我国地表温度进行实例模拟和验证,结果显示,该地表温度模型的平均反演精度达到2.54℃（R2=0.79）,是一种简单有效的被动微波遥感地表温度模拟方法。 相似文献
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Little is known concerning climate changes in the Eastern Baltic region during the last interglacial–glacial cycle and in particular, climate changes during the Weichselian. In this study, a quantitative reconstruction of the mean January and July temperature for the Medininkai-117 site in Lithuania is presented. The reconstruction is based on pollen and plant macrofossils from this site, which reveal that the vegetation was characteristic of many northern Europe sites during the Eemian and Early Weichselian. Gradual evolution of the vegetation suggests that relatively uniform climate conditions existed during the Eemian. Our reconstructions support the view of a relatively stable Eemian, with short cooling phases of low amplitude. A strong increase in temperature was apparent during the beginning of the interglacial and decrease during the transition to the Weichselian. Reconstructed July temperatures of the Eemian interglacial were approximately 2 °C higher than today (18.5 °C; today: 16.2 °C) and were similar to today for January (− 5.2 °C; today: − 5.1 °C). July temperatures during the Early Weichselian were only ~ 2°C lower than during the Eemian, whereas the January temperatures gradually decreased. Winter temperatures were relatively high (above − 10 °C) during the Early Weichselian. 相似文献
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