基于温度链浮标获取南极普里兹湾积雪和固定冰厚度的研究   总被引：2，自引：2，他引：0  

赵杰臣  杨清华  程斌  汪宁  惠凤鸣  沈辉  韩晓鹏  张林  TimoVihma 《海洋学报》2017,39(11):115-127

极地积雪和海冰厚度是气候变化的重要指标,也是船舶在冰区航行需要掌握的主要参数。2014和2015年在南极普里兹湾中山站附近布放了一种新式的温度链浮标,该浮标每天进行4次常规温度观测和1次加热升温观测,用于实时获取积雪和海冰剖面温度及厚度数据的研究。通过分析剖面温度曲线和升温曲线反映出的大气、积雪、海冰和海水4种介质的热传导特性差异,可利用人工识别的方法（人工经验法）获得大气/积雪、积雪/海冰和海冰/海水界面的位置。根据统计不同介质在升温响应和垂直温度梯度等方面的特性,找到合理阈值,可通过编写程序自动判断各界面的位置（自动程序法）。本文利用这两种方法来判断不同物质界面位置从而计算得到积雪和海冰厚度。与现场人工观测的海冰厚度相比,人工经验法的平均偏差和均方根偏差分别为2.1 cm和6.4 cm（2014年）以及4.3 cm和6.5 cm（2015年）,自动程序法的平均偏差和均方根偏差分别为-6.8 cm和6.4 cm（2014年）以及4.5 cm和 6.6 cm（2015年）;对于积雪,人工经验法与现场人工观测的平均偏差和均方根偏差分别为0.5 cm和 8.5 cm,而自动程序法的平均偏差和均方根偏差分别为4.7 cm和10.8 cm。自动程序法误差较人工经验法偏大,但考虑到整体冰厚和现场观测的误差,两种方法的结果均是可信的,精度是可以接受的。利用新式的温度链浮标实时获取南极普里兹湾积雪和海冰厚度是可行的。  相似文献   

Environmental literacy in interpreting endangered sustainability: Case studies from Thailand and the Sudan     

Minna Hares  Anu Eskonheimo  Timo Myllyntaus 《Geoforum》2006,37(1):128-144

This paper examines how people explain reasons and impacts of environmental change in the low-rain savanna of the central Sudan and mountainous forest lands of northern Thailand. The explanations are analyzed by using the concept of environmental literacy, which refers to the people’s ability to grasp the environment and its interactions. The paper aims to study people’s conceptions of the environment, which compose one factor in directing their behavior. For the study, rural inhabitants in the State of North Kordofan, the Sudan, and the Chiang Mai Province in Thailand were interviewed.It was noted that an individual’s capability to understand the environment is alone insufficient to address environmental problems because the efficient alleviation of the problems requires collective actions at all levels, and because of factors beyond an individual’s control. However, the results supported the assumption that the local people have knowledge of their environment that may help in developing sustainable environmental management practices. The main advantages of using the environmental literacy concept are argued to be its dynamic and synthetic essence, its link to sustainable behavior, and wide applicability in various contexts within heterogeneous communities.  相似文献   

‘Observations and Modelling of Cold-air Advection over Arctic Sea Ice’     

Timo?VihmaEmail author  Christof?Lüpkes  J?rg?Hartmann  Hannu?Savij?rvi 《Boundary-Layer Meteorology》2005,117(2):275-300

Aircraft observations of the atmospheric boundary layer (ABL) over Arctic sea ice were made during non-stationary conditions of cold-air advection with a cloud edge retreating through the study region. The sea-ice concentration, roughness, and ABL stratification varied in space. In the ABL heat budget, 80% of the Eulerian change in time was explained by cold-air advection and 20% by diabatic heating. With the cloud cover and inflow potential temperature profile prescribed as a function of time, the air temperature and near-surface fluxes of heat and momentum were well simulated by the applied two-dimensional mesoscale model. Model sensitivity tests demonstrated that several factors can be active in generating unstable stratification in the ABL over the Arctic sea ice in March. In this case, the upward sensible heat flux resulted from the combined effect of clouds, leads, and cold-air advection. These three factors interacted non-linearly with each other. From the point of view of ABL temperatures, the lead effect was far less important than the cloud effect, which influenced the temperature profiles via cloud-top radiative cooling and radiative heating of the snow surface. The steady-state simulations demonstrated that under overcast skies the evolution towards a deep, well-mixed ABL may take place through the merging of two mixed layers one related to mostly shear-driven surface mixing and the other to buoyancy-driven top-down mixing due to cloud-top radiative cooling.  相似文献   

Magmatic versus metamorphic origin of olivine-plagioclase coronas     

Geert-Jan L. de Haas  Timo G. Nijland  Peter J. Valbracht  Cees Maijer  Rob Verschure  Tom Andersen 《Contributions to Mineralogy and Petrology》2002,143(5):537-550

An SEM, REE, and mineral Sm-Nd isotope study on olivine-plagioclase coronas in the Vestre Dale gabbro, Norway, was carried out in order to solve the temporal relationships within these coronas. It is demonstrated that in contrast to common models, corona formation is a multistage, late-magmatic process, starting with the formation of orthopyroxene by (partial) dissolution of olivine, followed by the nucleation and rapid outward growth of orthopyroxene+spinel symplectites at its outer margin, and concluded by replacement of this precursory outer shell by calcic amphibole. Isotopic equilibrium between inner shell orthopyroxene and the magmatic assemblage, and the REE contents of orthopyroxene and outer shell amphibole also provide strong arguments for a magmatic origin, with the local availability of fractionated magma acting as a limiting factor. The absence of replacement of intercumulus clinopyroxene by amphibole also favours a late stage magmatic rather than a metamorphic origin for corona amphibole.  相似文献   

Multipurpose geochemical maps produced by integration of geochemical exploration data sets in The Paraná Shield, Brazil     

Otavio Augusto Boni Licht  Timo Tarvainen 《Journal of Geochemical Exploration》1996,56(3):167-182

Old geochemical datasets from the Paraná Shield of southern Brazil have been integrated into a new geochemical database and the results are presented as a series of multipurpose geochemical maps. Although the 24 datasets retrieved were analysed by three different laboratories, the maps produced correlate surprisingly well with bedrock geological features.The retrieval of old geochemical exploration data sets for the purpose of generating maps showing element depletions and enrichments is a powerful tool with a wide range of applications: trace elements such as Zn, Cu and Mo can significantly affect crop productivity; areas with high abundances of harmful elements such as As and F can be delineated in order to identify public health hazards; heavy metals such as Cd, Pb and Hg can be measured in order to better constrain knowledge of chemical background levels for environmental monitoring. The integration and manipulation of different data sets can however be complicated by the heterogeneity in sampling and analytical procedures.  相似文献   

Carbon balance in the forest sector in Finland during 1990–2039     

Timo Karjalainen  Seppo Kellomäki  Ari Pussinen 《Climatic change》1995,30(4):451-478

In this study we estimated the amount of carbon (C) stored in the forest growing stock and in wood-based products, and the C-sequestration capacity of the forest sector in Finland. Comparison of different management and utilization options for forest resources over the period 1990-2039 indicates that C is stored more efficiently in standing timber than in wood-based products. This implies that an appropriate increase in the length of the rotation in forestry could be optimal for balancing the needs of forest resources for C sequestration and timber production. Increased use of wood, based on sustainable use of forest resources, to substitute for fossil fuels and materials, could decrease the overall C emissions. Release of sequestered C back to the atmosphere can be delayed by prolonging product lifespans, by increasing recycling, or by disposing of discarded products in landfills. To delay C release, and affect the C balance, however, these changes should be substantial.In 1990, the net C balance of the growing stemwood stock was 5.5 Tg C/a, which increased to 16.3 Tg C/a by 2039 if in the future the use of wood would be at the level of the late 1980s. Increased use of wood resulted in a balance of 6.6 Tg C/a or -0.2 Tg C/a, depending on the extent of the use of wood. The average C balance in wood products for the whole period was 3.9, 5.6 or 6.6 Tg C/a, respectively. Changes in production capacity, and consideration of timber and product import and export decreased the average balance from 6.6 Tg C/a to 0.9–1.3 Tg C/a. By comparison, emission from the use of fossil fuels in 1990 C was 14.5 Tg C/a.  相似文献   

Direct Numerical Simulation of a Turbulent Channel Flow with Forchheimer Drag     

Bhattacharjee  Soumak  Mortikov  Evgeny  Debolskiy  Andrey  Kadantsev  Evgeny  Pandit  Rahul  Vesala  Timo  Sahoo  Ganapati 《Boundary-Layer Meteorology》2022,185(2):259-276

Boundary-Layer Meteorology - We characterize the turbulent flow, using direct numerical simulations (DNS), within a closed channel between two parallel walls with a canopy of constant areal density...  相似文献   

Spatial variability and trigger values of arsenic in the surface urban soils of the cities of Tampere and Lahti,Finland     

Gabriele Buttafuoco  Timo Tarvainen  Jaana Jarva  Ilaria Guagliardi 《Environmental Earth Sciences》2016,75(10):896

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Modelling of Dynamic Rock Fracture Process with a Rate-Dependent Combined Continuum Damage-Embedded Discontinuity Model Incorporating Microstructure     

Timo Saksala 《Rock Mechanics and Rock Engineering》2016,49(10):3947-3962

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Increased Carbon Sink in Temperate and Boreal Forests   总被引：6，自引：0，他引：6  

Jari Liski  Alexander V. Korotkov  Christopher F. L. Prins  Timo Karjalainen  David G. Victor  Pekka E. Kauppi 《Climatic change》2003,61(1-2):89-99

An intense search is under way to identify the `missing sink' in the world carbon budget of perhaps 2 Pg year^–1 (petagrams, or billiontonnes) of carbon, but its location and mechanism have proved elusive. Here we use a new forest inventory data set to estimate the carbon sink and the carbon pool of woody biomass in 55 countries that account for nearly all temperate or boreal forests and approximately half the world's total forest area. In each country there was a net accumulation of biomass; together, the carbon sink of woody biomass was 0.88 Pg year^–1 during the 1990swith estimated uncertainty from 0.71 to 1.1 Pg year^–1. Thisestimate, already about half of the missing sink, would probably be even larger if carbon accumulation in soil and detritus were also accounted for, but we are unable to quantify that additional sink. The sink is twice that estimated for the woody biomass of these forests a decade ago due to higher estimates for tree growth throughout the region and decreased timber harvests in Russia. In contrast, the new data indicate a carbon pool that is smaller than earlier estimates because of improved data for Russia and Australia.  相似文献