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排序方式: 共有104条查询结果,搜索用时 390 毫秒
51.
一、前 言 过去,大多把注意力都集中于大气预报变量的资料同化问题上,虽然,在这一方面仍有大量需要改进的问题。但是,人们越来越广泛地认识到地表面预报变量(表面温度,土壤水分含量和雪的厚度)在预报模式的建立和预报产品的解释中都起着重要作用。然而,对这些变量如何初始化的问题比较缺乏兴趣,这是令人非常吃惊的。对于这一情况有许多解释:期待改进仍然是相当有限的;通常用于全球范围的这些量没有直接的测量;模式对控制地表面变量演变的物理过程采用非常简化的参数等等。 不过,当我们设计新的预报系统“EMERAUDE”和“PERIDOT”的时候,我们决定采用新的、可靠的和简单的方法,但不是处理这一问题的一般的方法,下面将用一些结果来描述这一方法。 相似文献
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Aarab N Minier C Lemaire S Unruh E Hansen PD Larsen BK Andersen OK Narbonne JF 《Marine environmental research》2004,58(2-5):437-441
Several environmental chemicals are suspected to be responsible for adverse health effects on the reproductive system in various organisms. During this work, environmentally relevant concentrations of North Sea oil were used alone or in combination with alkylphenols and additional PAH to study the effect on vitellogenin-like protein expression and gonadal development in mussels. North Sea oil (0.5 ppm) induced the expression of phospho-proteins in both sexes indicating that some compounds are oestrogen-mimics. This induction was not seen in samples dosed with the mixture but signs of toxic effects were observed in the gonads. Indeed, numerous degenerating ovarian follicles in females and foci, similar to vertebrate melanomacrophage centres, were observed in testes. 相似文献
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RIPGIS-NET, an Environmental System Research Institute (ESRI's) ArcGIS 9.2/9.3 custom application, was developed to derive parameters and visualize results of spatially explicit riparian groundwater evapotranspiration (ETg), evapotranspiration from saturated zone, in groundwater flow models for ecohydrology, riparian ecosystem management, and stream restoration. Specifically RIPGIS-NET works with riparian evapotranspiration (RIP-ET), a modeling package that works with the MODFLOW groundwater flow model. RIP-ET improves ETg simulations by using a set of eco-physiologically based ETg curves for plant functional subgroups (PFSGs), and separates ground evaporation and plant transpiration processes from the water table. The RIPGIS-NET program was developed in Visual Basic 2005, .NET framework 2.0, and runs in ArcMap 9.2 and 9.3 applications. RIPGIS-NET, a pre- and post-processor for RIP-ET, incorporates spatial variability of riparian vegetation and land surface elevation into ETg estimation in MODFLOW groundwater models. RIPGIS-NET derives RIP-ET input parameters including PFSG evapotranspiration curve parameters, fractional coverage areas of each PFSG in a MODFLOW cell, and average surface elevation per riparian vegetation polygon using a digital elevation model. RIPGIS-NET also provides visualization tools for modelers to create head maps, depth to water table (DTWT) maps, and plot DTWT for a PFSG in a polygon in the Geographic Information System based on MODFLOW simulation results. 相似文献
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Kennedy K Schroeder T Shaw M Haynes D Lewis S Bentley C Paxman C Carter S Brando VE Bartkow M Hearn L Mueller JF 《Marine pollution bulletin》2012,65(4-9):292-305
Photosystem II (PSII) herbicides are used in large quantities on agricultural lands adjoining the Great Barrier Reef (GBR). Routine monitoring at 14 sites in inshore waters of the GBR using passive sampling techniques detected diuron (32-94% of sampling periods) at maximum concentrations of 1.7-430ng L(-1) in the relatively pristine Cape York Region to the Mackay Whitsunday Region, respectively. A PSII herbicide equivalent (PSII-HEq) index developed as an indicator for reporting was dominated by diuron (average contribution 89%) and typically increased during the wet season. The maximum PSII-HEq indicates the potential for photosynthetic inhibition of diatoms, seagrass and coral-symbionts. PSII herbicides were significantly positively correlated with remotely sensed coloured dissolved organic matter, a proxy for freshwater extent. Combining these methods provides for the first time the potential to cost-effectively monitor improvements in water quality entering the GBR with respect to exposure to PSII herbicides. 相似文献
55.
The effects of the photosystem II (PSII) herbicide diuron was assessed on thirteen tropical foraminifera hosting diatom, dinoflagellate, red or green algae endosymbionts. Inhibition of photosynthesis (reduced ΔF/F(m)(')) by diuron depended on both symbiont type and test ultrastructure, with greatest sensitivity observed for diatom- and chlorophyte-hosting species (24h IC(25) 2.5-4μg L(-1)). Inhibition kinetics was slow (24-48h until maximum inhibition) in comparison with corals, suggesting structural differences may influence herbicide uptake and transport. Although foraminifera were generally less sensitive to direct effects of diuron (inhibition ΔF/F(m)(')) than other marine phototrophs, damage to PSII (reduction F(v)/F(m)) occurred at concentrations lower than observed for other organisms (24h IC(25) 3-12μg L(-1)). Damage to PSII was highly light dependent and occurred at very low light intensities indicating limited photoprotective capacity. The high diversity, widespread occurrence and relative sensitivity make foraminifera good bioindicator organisms to evaluate phytotoxic stress on coral reefs. 相似文献
56.
Stockmann KD Anderson NM Skog KE Healey SP Loeffler DR Jones G Morrison JF 《Carbon balance and management》2012,7(1):1
Background
Global forests capture and store significant amounts of CO2 through photosynthesis. When carbon is removed from forests through harvest, a portion of the harvested carbon is stored in wood products, often for many decades. The United States Forest Service (USFS) and other agencies are interested in accurately accounting for carbon flux associated with harvested wood products (HWP) to meet greenhouse gas monitoring commitments and climate change adaptation and mitigation objectives. This paper uses the Intergovernmental Panel on Climate Change (IPCC) production accounting approach and the California Forest Project Protocol (CFPP) to estimate HWP carbon storage from 1906 to 2010 for the USFS Northern Region, which includes forests in northern Idaho, Montana, South Dakota, and eastern Washington. 相似文献57.
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高分辨率层序地层学——创新,应用及发展前景 总被引:4,自引:0,他引:4
高分辨率层序地层学的研究有了巨大的发展,其主要有两个方面的应用,一是全球海平面变化曲线的建立和对比,二是等时性剖面中的岩性特征预测。研究表明,沉积学、生物地层学、构造地质学及地震学等证据的结构,对提高分辨率层序地层学的解释水平是十分必要的。文集收集的论文反映了当代层序地层学研究的深度和广度。 相似文献