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991.
Birger Ulf Hansen Ole Humlum Niels Nielsen Dorte P. Lundqvist Ditte L. Jansen Christian Christiansen 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2013,113(2):93-109
An automatic meteorological station has been operating at the Arctic Station (69°15'N, 53°31'W) in West Greenland since 1990. This paper summarises meteorological parameters during 2002, including snow cover, ground temperatures and active layer development, and air temperatures at the Station during the last 12 years are compared to large scale trends during the last century. A compilation of 93 sedimentation rate determinations based on 210Pb dating has been carried out for the North Sea-Baltic Sea transition area from a database containing 165 determinations carried out by Danish institutions. In the depositional parts of the area sedimentation rates generally range 25–6403 g m?2 y?1. An extreme rate of 13351 g m?2 y?1 is observed on a station in the Skagerrak. Sedimentation rates significantly increase with depth indicating that the Skagerrak and northern parts of the Kattegat as well as the deep basins in the Baltic Sea act as depocentres for fine-grained sediments. Apparently, sedimentation rates have increased in recent years. 相似文献
992.
993.
基于中国第28次南极科学考察长城站越冬期间获取的常规气象和海冰观测资料,结合统计的1985—2010年气候值,对比分析了长城站2012年的气象及海冰特征。气象分析表明,该年平均气压和气温偏低,N—W风向频率显著偏低,E—SE风向频率显著偏高;雾日偏少,降雪量、吹雪及雪暴显著偏多;针对观测期间某些月份比较明显的气象要素和天气现象异常,从大气环流角度进行了分析解释。海冰观测表明,长城湾冰情变化受大气动力作用影响大,冰情稳定性差,外围海域海冰极不稳定,2012年4月至2012年11月冰情几经进退,先后交替出现3个完全冰冻和3个部分冰冻期。 相似文献
994.
北京猿人洞13个堆积层可划分为7个堆积旋回。每个旋回早期的堆积层(砂、粉砂、粘土和钙扳层),含有暖温带气候特征的哺乳动物和孢粉组合;晚期的堆积层(洞穴角砾与巨砾层),含有温带较干冷气候特征的哺乳动物和孢粉组合。堆积层年代测定数据表明北京猿人洞7个堆积旋回形成于更新世中期,年代为128-730ka,与中国黄土层L2-S7,相当,可与深海氧同位素阶段6-19和气候旋回C-I对比。北京猿人在此洞断续生活了约35万年,即从距今约60万年的第5堆积旋回(δ18O第14阶段)至距今约25万年的第2堆积旋回(δ18O第8阶段)。 相似文献
995.
The spatial distribution of snow cover on the central Arctic sea ice is investigated here based on the observations made during the Third Chinese Arctic Expedition. Six types of snow were observed during the expedition: new/recent snow, melt-freeze crust, icy layer, depth hoar, coarse-grained, and chains of depth hoar. Across most measurement areas, the snow surface was covered by a melt-freeze crust 2-3 cm thick, which was produced by alternate strong solar radiation and the sharp temperature decrease over the summer Arctic Ocean. There was an intermittent layer of snow and ice at the base of the snow pack. The mean bulk density of the snow was 304.01±29.00 kg/m3 along the expedition line, and the surface values were generally smaller than those of the subsurface, confirming the principle of snow densification. In addition, the thicknesses and water equivalents of the new/recent and total-layer snow showed a decreasing trend with latitude, suggesting that the amount of snow cover and its spatial variations were mainly determined by precipitation. Snow temperature also presented significant variations in the vertical profile, and ablation and evaporation were not the primary factors in the snow assessment in late summer. The mean temperature of the surface snow was 2.01±0.96°C, which was much higher than that observed in theinterface of snow and sea ice. 相似文献
996.
A. D. Koussis E. Georgopoulou A. Kotronarou K. Mazi P. Restrepo G. Destouni 《水文科学杂志》2013,58(7):1234-1245
Abstract We investigate the general methodology for an intensive development of coastal aquifers, described in a companion paper, through its application to the management of the Akrotiri aquifer, Cyprus. The Zakaki area of that aquifer, adjacent to Lemessos City, is managed such that it permits a fixed annual agricultural water demand to be met, as well as and a fraction of the water demand of Lemessos, which varies according to available surface water. Effluents of the Lemessos wastewater treatment plant are injected into the aquifer to counteract the seawater intrusion resulting from the increased pumping. The locations of pumping and injection wells are optimized based on least-cost, subject to meeting the demand. This strategy controls sea intrusion so effectively that desalting of only small volumes of slightly brackish groundwater is required over short times, while ~2.3 m3 of groundwater is produced for each 1 m3 of injected treated wastewater. The cost over the 20-year period 2000–2020 of operation is ~40 M€ and the unit production cost of potable water is under 0.2 €/m3. The comparison between the deterministic and stochastic analyses of the groundwater dynamics indicates the former as conservative, i.e. yielding higher groundwater salinity at the well. The Akrotiri case study shows that the proposed aquifer management scheme yields solutions that are preferable to the widely promoted seawater desalination, also considering the revenues from using the treated wastewater for irrigation. Citation Koussis, A. D., Georgopoulou, E., Kotronarou, A., Mazi, K., Restrepo, P., Destouni, G., Prieto, C., Rodriguez, J. J., Rodriguez-Mirasol, J., Cordero, T., Ioannou, C., Georgiou, A., Schwartz, J. & Zacharias, I. (2010) Cost-efficient management of coastal aquifers via recharge with treated wastewater and desalination of brackish groundwater: application to the Akrotiri basin and aquifer, Cyprus. Hydrol. Sci. J. 55(7), 1234–1245. 相似文献
997.
998.
利用船测数据以及Landsat-7 ETM+影像评估南极海冰区AMSR-E海冰密集度 总被引:3,自引:1,他引:2
利用第26次中国南极科学考察期间收集的海冰密集度船基观测资料以及由Landsat-7 ETM+得到的海冰密集度来验证AMSR-E南极海冰区海冰密集度产品的精度。AMSR-E海冰密集度与船基目视观测的海冰密集度存在着一定的线性关系(R2=0.816), 但两者匹配得并不是很好。与ETM+海冰密集度相比,AMSR-E数据趋向于低估海冰密集度,在25景晴空条件下的ETM+影像中,平均海冰密集度偏差(AMSR-E海冰密集度-ETM+海冰密集度)从-5.33%到-21.5%,而相应的均方根误差RMSE (Root Mean Squared Errors)从13.7%到33.8%。依据Landsat-7 ETM+ 海冰分类,AMSR-E数据海冰密集度最大的误差产生于新冰区。 相似文献
999.
1000.
FY-1D is the second national operation meteorological satellite of China, and is much better compared to monitoring fog. However, research on monitoring fog using FY-1D is very few. In this paper, based on the typical FY-1D data, a fog’s spectral characteristics in the different channels are analyzed using the histogram analysis method, and a method of monitoring fog using FY-1D is suggested. The results indicate that the 1st and 4th channels are the representative channels of FY-1D for the identification of fog. In the 1st channel, the fog is with uniform veins, smooth top, and clear-cut boundary, and its albedo is 20%~48%. In the 4th channel, the fog’s brightness and temperature is 272~289K, and the difference value between the fog’s and the ground surface’s is not more than 6K. 相似文献