New insights into the spatial variability of the surface water carbon dioxide in varying sea ice conditions in the Arctic Ocean   总被引：1，自引：0，他引：1  

Agneta Fransson  Melissa Chierici  Yukihiro Nojiri 《Continental Shelf Research》2009

In the summer of 2005, continuous surface water measurements of fugacity of CO₂ (fCO₂^sw), salinity and temperature were performed onboard the IB Oden along the Northwest Passage from Cape Farwell (South Greenland) to the Chukchi Sea. The aim was to investigate the importance of sea ice and river runoff on the spatial variability of fCO₂ and the sea–air CO₂ fluxes in the Arctic Ocean. Additional data was obtained from measurements of total alkalinity (A_T) by discrete surface water and water column sampling in the Canadian Arctic Archipelago (CAA), on the Mackenzie shelf, and in the Bering Strait. The linear relationship between A_T and salinity was used to evaluate and calculate the relative fractions of sea ice melt water and river runoff along the cruise track. High-frequency fCO₂^sw data showed rapid changes, due to variable sea ice conditions, freshwater addition, physical upwelling and biological processes. The fCO₂^sw varied between 102 and 678 μatm. Under the sea ice in the CAA and the northern Chukchi Sea, fCO₂^sw were largely CO₂ undersaturated of approximately 100 μatm lower than the atmospheric level. This suggested CO₂ uptake by biological production and limited sea–air CO₂ gas exchange due to the ice cover. In open areas, such as the relatively fresh water of the Mackenzie shelf and the Bering Strait, the fCO₂^sw values were close to the atmospheric CO₂ level. Upwelling of saline and relatively warm water at the Cape Bathurst caused a dramatic fCO₂^sw increase of about 100 μatm relative to the values in the CAA. At the southern part of the Chukchi Peninsula we found the highest fCO₂^sw values and the water was CO₂ supersaturated, likely due to upwelling. In the study area, the calculated sea–air CO₂ flux varied between an oceanic CO₂ sink of 140 mmol m⁻² d⁻¹ and an oceanic source of 18 mmol m⁻² d⁻¹. However, in the CAA and the northern Chukchi Sea, the sea ice cover prevented gas exchange, and the CO₂ fluxes were probably negligible at this time of the year. Assuming that the water was exposed to the atmosphere by total melting and gas exchange would be the only process, the CO₂ undersaturated water in the ice-covered areas will not have the time to reach the atmospheric CO₂ value, before the formation of new sea ice. This study highlights the value of using high-frequency measurements to gain increased insight into the variable and complex conditions, encountered on the shelves in the Arctic Ocean.  相似文献   

Surface latent heat flux anomalies preceding inland earthquakes in China     

Kai Qin  Guangmeng Guo  Lixin Wu 《地震学报(英文版)》2009,(5):555-562

  相似文献   

利用地磁脉动预报地球同步轨道相对论电子通量的方法研究   总被引：2，自引：0，他引：2       下载免费PDF全文

何甜  刘四清  薛炳森  程永宏  龚建村 《地球物理学报》2009,52(10):2419-2427

本文利用低纬地磁台站的Pi1、Pi2地磁脉动（Pi1-2）资料和地球同步轨道的Pc5地磁脉动资料,对2004年1月到2006年12月38个磁暴事件的地磁脉动参数进行了统计分析.在此基础上,考虑相对论电子的局部加速机制,并加入损失机制,建立了一个初步的磁暴期间地球同步轨道相对论电子通量对数值的预报模型.利用该模型,我们对上述38个磁暴事件进行预报试验,最优化结果是：相对论电子通量对数值的预测值和观测值之间的线性相关系数为0.82,预报效率为0.67.这说明该模式具有较好的预报效果,也表明利用地磁脉动参数进行相对论电子通量预报是可行的.  相似文献   

冲绳海槽南段与中、北段构造活动性对比的热模拟研究          下载免费PDF全文

孟林  张训华  温珍河  孟祥君  王明健 《地球物理学报》2016,59(9):3302-3317

受新生代太平洋板块弧后扩张剧烈活动的地缘特性影响,冲绳海槽构造特征复杂,南、中、北段在热液活动、断裂性质、火成岩特性、扩张时代等方面存在显著不同,因此认识该区各段构造活动性对查清其复杂地质特征具有重要意义.本文依据前人通过磁异常反演得到的居里面深度资料,利用热模拟的方法,对冲绳海槽各段深、浅构造活动性进行了探讨.模拟结果表明,南段软流层构造活动强度约为中、北段的6倍,而岩石圈浅层构造活动却相对较弱.该结论与前人所得到的地质地球物理资料相符,主要表现为:相对于中、北段,南段在海槽总体演化历程上裂陷较深;海底火成岩岩浆源区较深,结晶分异程度较弱,同化混染程度较强;切穿沉积基底的大型断裂较为发育,而沉积层内部的小型断裂分布相对稀疏;沉积层岩浆侵入活动较弱,海底所呈现出的热液活动区数量较少;现代地震活动较多,震源深度较大.根据模拟结果与实际资料的对比分析我们可以推测:(1)冲绳海槽北段可能还有一些热液区没有被探测到,也可能在历史演化进程中失去活力,或者被第四系沉积物覆盖;(2)南段存在孕育更多热液活动区的潜力.  相似文献   

Dynamics of algae growth and nutrients in experimental enclosures culturing bighead carp and common carp:Phosphorus dynamics     

《国际泥沙研究》2016,(2):173-180

This is the third paper of the series about “Dynamics of algae growth and nutrients in experimental enclosures culturing bighead carp and common carp”. In this paper, phosphorus dynamics were inves-tigated under the condition of culturing bighead carp and common carp with added fish food (nitrogen dynamics is discussed in the second paper because their behaviors are so different from each other). Nearly fifty days’ observation results indicated that the reservoir water was typical of “phosphorus limited” water, and soluble reactive phosphorus (SRP) was the main constituent of measured total phosphorus (TP). The presence of fish food resulted in significantly higher SRP, dissolved total phos-phorus (DTP) and TP concentrations in contrast with the reservoir water. Moreover, continuous supply of fish food led to the decline of total nitrogen to total phosphorus (TN:TP) from more than 100 to less than 5. Variations in the ratio of TN to TP favored the growth of blue-green algae. Fish species affected phosphorus concentrations, and culturing bait-eating common carp contributed more to reducing the SRP, DTP and TP concentrations than culturing planktivorous bighead carp. 0.5%, 4.1%and 3.1%TP can be removed in enclosures with culturing bighead carp, common carp and mixed bighead carp and common carp, respectively. Abundant phosphorus in the fish culturing activities may be present as the uneaten food, algae cells, and within the water column and sediment, which should be taken into serious con-sideration for the target of future water eutrophication prevention and safety of the drinking water supply.  相似文献   

Enhanced modeling of latent heat flux from urban surfaces in the Noah/single-layer urban canopy coupled model     

ShiGuang Miao  Fei Chen 《中国科学:地球科学(英文版)》2014,57(10):2408-2416

The numerical modeling of the impacts of urban buildings in mesoscale meteorological models has gradually improved in recent years. Correctly representing the latent heat flux from urban surfaces is a key issue in urban land-atmosphere coupling studies but is a common weakness in current urban canopy models. Using the surface energy balance data at a height of 140 m from a 325 m meteorological tower in Beijing, we conducted a 1-year continuous off-line simulation by using a coupled land surface model and a single-layer urban canopy model and found that this model has a relatively large systematic error for simulated latent heat flux. To improve the numerical method for modeling latent heat flux from urban surfaces, we combined observational analysis and urban land surface model to derive an oasis effect coefficient for urban green areas; to develop a temporal variation formula for water availability in urban impervious surfaces; and to specify a diurnal profile and the maximum values of anthropogenic latent heat release for four seasons. These results are directly incorporated into the urban land surface model to improve model performance. In addition, this method serves as a reference for studies in other urban areas.  相似文献   

Impacts of Different Membrane Module Designs in Anaerobic Submerged Membrane Bioreactors          下载免费PDF全文

Mustafa Aslan  Yusuf Saatçı 《洁净——土壤、空气、水》2014,42(12):1759-1764

  相似文献   

基于涡动相关仪验证的SEBS模型对黑河中游地表蒸散发的估算研究     

吴雪娇  周剑  李妍  潘晓多  周彦召 《冰川冻土》2014,36(6):1538-1547

在我国西北干旱和半干旱地区, 农业收获主要依靠灌溉保证, 灌溉绿洲的蒸散发(ET)是当地水资源的主要消耗. 通过遥感估算区域灌溉绿洲的ET对于地区合理利用水资源极其重要, 利用MODIS/Terra 影像, 基于物理过程的地表能量平衡模型(SEBS), 结合WRF模式输出的气候驱动数据和地面观测数据来估算黑河中游地区的地表通量和日蒸散发(ET_daily). 估算的ET用不同下垫面的涡动相关仪观测数据进行验证, 结果显示: SEBS模型估算的不同下垫面的ET_daily具有很好的拟合效果(R²=0.96, P<0.001), 在灌溉绿洲估算的ET_daily比实测值偏高, 说明干旱、半干旱地区灌溉绿洲土壤水分胁迫是影响ET的主要因素. 模型估算绿洲作物生长期间的ET_daily和实测的ET_daily平均相对误差为12.5%, 精度在观测的能量不闭合误差以内且精度比戈壁和沙漠地区高.  相似文献   

全球大洋季节内尺度上海-气相互作用特征分析     

席婧嫄  周磊  姜良红 《海洋学研究》2014,32(3):1-8

判定局地海-气相互作用的特征对海-气耦合模式中应用哪种形式的“强迫模拟”具有重要指导作用。本文根据海表热通量异常与海表温度异常及海表温度变率之间的相关关系,对全球大洋季节内尺度上的海-气相互作用特征进行了综合分析。结果表明:(1)南、北半球亚热带地区海-气相互作用的特征主要表现为大气对海洋的强迫,且在夏季(北半球为6—8月,南半球为12—翌年2月)强迫作用的范围最大,冬季强迫作用的范围最小;(2)赤道中、东太平洋及赤道大西洋地区海-气相互作用的特征全年表现为海洋对大气的强迫,印度洋索马里沿岸、阿拉伯海以及孟加拉湾地区仅在6—8月表现出海洋强迫大气的现象,而孟加拉湾则在9—11月表现为大气强迫海洋;(3)45°N(S)以上的高纬度地区海表温度的异常和变率无法用局地热通量的交换来解释,这是因为该区域海表温度的变化主要由平流等海洋内部动力过程决定,因此海-气之间在季节内尺度上的相互作用不明显。在某些海区,季节内尺度上的海-气相互作用关系与季节以上时间尺度的这种关系可能会有明显不同。  相似文献   

一次东北冷涡暴雨的水汽输送特征和位涡分析   总被引：1，自引：0，他引：1  

王宁  徐祥德  徐洪雄  慕秀香  牛立强  李尚锋 《地理科学》2014,34(2):211-219

通过对2010年7月27~29日吉林省一次较大范围的冷涡暴雨、大暴雨过程进行诊断分析,建立了此类暴雨的天气概念模型：200 hPa呈现“两脊一槽”型,高空急流呈辐散状位于吉林省上空,急流中心最大风速≥60 m/s;500 hPa东北冷涡强烈发展,鄂海阻高稳定维持是此次强降水发生的重要天气系统,中心最大风速≥20 m/s的偏西风急流带横穿吉林省中部;850 hPa风速≥12 m/s的3条急流带在吉林省中东部地区交汇,形成低层辐合、高层辐散的气旋性涡度柱,较强的垂直上升气柱一直向上伸展到500 hPa附近,极有利于对流的发展和强降水的维持。通过计算整层水汽通量与吉林省逐6 h平均降水量的相关矢量场,结果表明：偏西、偏南及偏北3条水汽通道在吉林省中南部汇集是此次强降水发生的重要条件,暴雨落区与整层水汽通量汇合区密切相关,水汽输送以经向(南北方)水汽流入为主。暴雨期间具有较好的动力、热力及能量条件,特别是湿对流有效位能明显偏强,强降水出现在对流有效位能 (CAPE)值由极大值开始下降的过程中。干侵入是激发冷涡发生、发展的动力条件之一,≥1 PVU(位涡单位)的高位涡舌在下降的过程中,同时南移,与中部地区强降水落区自北向南移动相吻合。  相似文献