Air–Sea \mathrm{CO}_{2} Gas Transfer Velocity in a Shallow Estuary     

Eva Thorborg Mørk  Lise Lotte Sørensen  Bjarne Jensen  Mikael K. Sejr 《Boundary-Layer Meteorology》2014,151(1):119-138

The air–sea transfer velocity of $\mathrm{CO}_{2}\, (k_{\mathrm{CO}_{2}})$ was investigated in a shallow estuary in March to July 2012, using eddy-covariance measurements of $\mathrm{CO}_{2}$ fluxes and measured air–sea $\mathrm{CO}_{2}$ partial-pressure differences. A data evaluation method that eliminates data by nine rejection criteria in order to heighten parametrization certainty is proposed. We tested the data evaluation method by comparing two datasets: one derived using quality criteria related solely to the eddy-covariance method, and the other derived using quality criteria based on both eddy-covariance and cospectral peak methods. The best parametrization of transfer velocity normalized to a Schmidt number of 600 $(k_{600})$ was determined to be: $k_{600} = 0.3\,{U_{10}}^{2.5}$ where $U_{10}$ is the wind speed in m $\mathrm{s}^{-1}$ at 10 m; $k_{600}$ is based on $\mathrm{CO}_{2}$ fluxes calculated by the eddy-covariance method and including the cospectral peak method criteria. At low wind speeds, the transfer velocity in the shallow water estuary was lower than in other coastal waters, possibly a symptom of low tidal amplitude leading to low intensity water turbulence. High transfer velocities were recorded above wind speeds of 5 m $\mathrm{s}^{-1}$ , believed to be caused by early-breaking waves and the large fetch (6.5 km) of the estuary. These findings indicate that turbulence in both air and water influences the transfer velocity.  相似文献   

The population of natural Earth satellites     

Mikael Granvik  Jeremie Vaubaillon  Robert Jedicke 《Icarus》2012,218(1):262-277

We have for the first time calculated the population characteristics of the Earth’s irregular natural satellites (NESs) that are temporarily captured from the near-Earth-object (NEO) population. The steady-state NES size–frequency and residence-time distributions were determined under the dynamical influence of all the massive bodies in the Solar System (but mainly the Sun, Earth, and Moon) for NEOs of negligible mass. To this end, we compute the NES capture probability from the NEO population as a function of the latter’s heliocentric orbital elements and combine those results with the current best estimates for the NEO size–frequency and orbital distribution. At any given time there should be at least one NES of 1-m diameter orbiting the Earth. The average temporarily-captured orbiter (TCO; an object that makes at least one revolution around the Earth in a co-rotating coordinate system) completes (2.88 ± 0.82) rev around the Earth during a capture event that lasts (286 ± 18) d. We find a small preference for capture events starting in either January or July. Our results are consistent with the single known natural TCO, 2006 RH₁₂₀, a few-meter diameter object that was captured for about a year starting in June 2006. We estimate that about 0.1% of all meteors impacting the Earth were TCOs.  相似文献   

Multi-Region Boundary Element Analysis for Coupled Thermal-Fracturing Processes in Geomaterials     

Baotang Shen  Hyung-Mok Kim  Eui-Seob Park  Taek-Kon Kim  Manfred W. Wuttke  Mikael Rinne  Tobias Backers  Ove Stephansson 《Rock Mechanics and Rock Engineering》2013,46(1):135-151

This paper describes a boundary element code development on coupled thermal–mechanical processes of rock fracture propagation. The code development was based on the fracture mechanics code FRACOD that has previously been developed by Shen and Stephansson (Int J Eng Fracture Mech 47:177–189, 1993) and FRACOM (A fracture propagation code—FRACOD, User’s manual. FRACOM Ltd. 2002) and simulates complex fracture propagation in rocks governed by both tensile and shear mechanisms. For the coupled thermal-fracturing analysis, an indirect boundary element method, namely the fictitious heat source method, was implemented in FRACOD to simulate the temperature change and thermal stresses in rocks. This indirect method is particularly suitable for the thermal-fracturing coupling in FRACOD where the displacement discontinuity method is used for mechanical simulation. The coupled code was also extended to simulate multiple region problems in which rock mass, concrete linings and insulation layers with different thermal and mechanical properties were present. Both verification and application cases were presented where a point heat source in a 2D infinite medium and a pilot LNG underground cavern were solved and studied using the coupled code. Good agreement was observed between the simulation results, analytical solutions and in situ measurements which validates an applicability of the developed coupled code.  相似文献   

Strengthened East Asian summer monsoons during a period of high-latitude warmth? Isotopic evidence from Mio-Pliocene fossil mammals and soil carbonates from northern China     

Benjamin H. Passey  Linda K. Ayliffe  Anu Kaakinen  Zhaoqun Zhang  Jussi T. Eronen  Yanming Zhu  Liping Zhou  Thure E. Cerling  Mikael Fortelius 《Earth and Planetary Science Letters》2009,277(3-4):443-452

The East Asian monsoons have fluctuated in concert with high-latitude warmth during the past several hundred thousand years, with humid summer monsoon-dominant climates characterizing warm intervals, including interglacials and interstadials, and arid winter monsoon-dominant climates characterizing cool intervals, including glacials and stadials. Of the states comprising the mid-Pleistocene to recent climatic regime, interglacials are most similar in terms of high latitude ice volumes and temperatures to those extant during the late Miocene and early Pliocene. Thus, an important question is whether Mio-Pliocene climates in northern China were analogous to a hypothetical ‘prolonged interglacial state,’ with increased summer monsoon precipitation and expansion of forest and steppe environments at the expense of desert environments.We utilize new and previously published carbon isotopic data from fossil teeth and soil carbonates to place constraints on paleovegetation distributions and to help infer the behavior of the monsoon system between ～ 7 and 4 Ma. We find that plants using the C₄ photosynthetic pathway—which today are largely grasses found in regions with warm season precipitation—were present in northern China by late Miocene time, demonstrating that the C₄ expansion in China was not significantly delayed compared to the global C₄ event. During the late Miocene–early Pliocene interval, soil carbonate and tooth enamel δ¹³C data indicate: 1) that nearly pure C₃-plant ecosystems existed in the southern Chinese Loess Plateau (CLP), and therefore ecosystems there were dominated by woody dicot, herbaceous dicot, or cool-season grass vegetation (or a combination of these), and 2) that the CLP was characterized by a pattern of northward-increasing C₄ vegetation and aridity. Utilizing a broadened conceptual model for interpreting δ¹³C data, and citing independent faunal, floral, and lithostratgraphic data, we suggest that these patterns reflect northward expansion of forest and steppe ecosystems and relatively humid monsoon climates during the late Miocene and early Pliocene. An important implication of this interpretation is that the forcing mechanism illuminated by the temporal correlation during the Pleistocene between warm high latitudes and strong East Asian summer monsoons is a robust feature of the Eurasian tectonic–climatic system that predates the Plio-Pleistocene climatic reorganization.  相似文献   

A multivariate assessment of coastal eutrophication. Examples from the Gulf of Finland, northern Baltic Sea   总被引：1，自引：0，他引：1  

Lundberg C  Lönnroth M  von Numers M  Bonsdorff E 《Marine pollution bulletin》2005,50(11):1185-1196

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Nudging the Impasse? Lessons From the Nationwide Online Wolf Management Forum in Finland     

Matti Salo  Juha Hiedanpää  Mikael Luoma  Jani Pellikka 《社会与自然资源》2017,30(9):1141-1157

During the early 2010s, Finnish wolf (Canis lupus) policy reached an impasse. Unfavorable conservation status, intensifying wolf–human conflict, civil disobedience, legislative confusion, and administrative frustration characterized the situation. As part of a participatory updating process for the Finnish national wolf management plan in 2014, we organized a nationwide wolf management forum to explore how e-participation could be used to nurture deliberation for improved wolf policy. We present our interactive method and the resulting wolf territory-based solutions to the wolf problems that the participants of a nationwide online forum identified. The theoretical and practical significance of our work is that we ascribe value to the functional features of these solutions as modifications to the action environment, shared by people and wolves. In this vein, we discuss the role of e-deliberation on the path toward an institutional fit, and we consider how local decision making could help to implement promising wolf territory-level policy interventions.  相似文献   

Groundwater resources of Uzbekistan: an environmental and operational overview   总被引：1，自引：0，他引：1  

Shavkat Rakhmatullaev  Frédéric Huneau  Jusipbek Kazbekov  Hélène Celle-Jeanton  Mikael Motelica-Heino  Philippe Le Coustumer  Jamoljon Jumanov 《Central European Journal of Geosciences》2012,4(1):67-80

As a result of the massive irrigation development during the Soviet Union era and intensive chemization of agriculture, the surface runoff quality has been degraded in this arid and endorheic region. Moreover hydraulically related groundwater has also been affected. Excessive irrigation has lead to land salinization, which now threatens the soil quality of significant areas where crop yields would be at risk in the future. Since the collapse of the Soviet Union, institutional changes have been undertaken for the management of natural resources and water infrastructure. At present, underdeveloped and inadequate systems have been practiced with respect to groundwater use and management. This paper analyzes the present extent of groundwater resources with consideration to their reserves, quality evolution, and to technical, institutional and transboundary management practices in Uzbekistan.  相似文献   

AstroGrid-D: Grid technology for astronomical science     

Harry Enke  Matthias Steinmetz  Hans-Martin Adorf  Alexander Beck-Ratzka  Frank Breitling  Thomas Brüsemeister  Arthur Carlson  Torsten Ensslin  Mikael Högqvist  Iliya Nickelt  Thomas Radke  Alexander Reinefeld  Angelika Reiser  Tobias Scholl  Rainer Spurzem  Jürgen Steinacker  Wolfgang Voges  Joachim Wambsganß  Steve White 《New Astronomy》2011,16(2):79-93

We present status and results of AstroGrid-D, a joint effort of astrophysicists and computer scientists to employ grid technology for scientific applications. AstroGrid-D provides access to a network of distributed machines with a set of commands as well as software interfaces. It allows simple use of computer and storage facilities and to schedule or monitor compute tasks and data management. It is based on the Globus Toolkit middleware (GT4).Chapter 1 describes the context which led to the demand for advanced software solutions in Astrophysics, and we state the goals of the project.We then present characteristic astrophysical applications that have been implemented on AstroGrid-D in chapter 2. We describe simulations of different complexity, compute-intensive calculations running on multiple sites (Section 2.1), and advanced applications for specific scientific purposes (Section 2.2), such as a connection to robotic telescopes (Section 2.2.3). We can show from these examples how grid execution improves e.g. the scientific workflow.Chapter 3 explains the software tools and services that we adapted or newly developed. Section 3.1 is focused on the administrative aspects of the infrastructure, to manage users and monitor activity. Section 3.2 characterises the central components of our architecture: The AstroGrid-D information service to collect and store metadata, a file management system, the data management system, and a job manager for automatic submission of compute tasks.We summarise the successfully established infrastructure in chapter 4, concluding with our future plans to establish AstroGrid-D as a platform of modern e-Astronomy.  相似文献   

Groundwater resources use and management in the Amu Darya River Basin (Central Asia)   总被引：2，自引：0，他引：2  

Shavkat Rakhmatullaev  Frédéric Huneau  Jusipbek Kazbekov  Philippe Le Coustumer  Jamoljon Jumanov  Bouchra El Oifi  Mikael Motelica-Heino  Zbynek Hrkal 《Environmental Earth Sciences》2010,59(6):1183-1193

This paper analyses groundwater resources use and management in the socio-economic context of the Amu Darya River Basin which covers a part of the following landlocked Central Asian countries: Afghanistan, Tajikistan, Turkmenistan and Uzbekistan. These agrarian nations for sustaining their vital agricultural productions started to use groundwater during the recent drought years (1998–2001) because of its relatively good quality and quantity and as an alternative to highly mineralized surface waters. Present extent of groundwater resources use is discussed with consideration to their reserves, quality, and institutional management and transboundary aspects within the basin. After the collapse of the centralized water resources management system and infrastructure of the former Soviet Union, new underdeveloped systems are being practiced over the whole Amu Darya River Basin. The critical situation of groundwater management in Afghanistan is also discussed. This work attempts to document the management and use of groundwater in the Amu Darya Basin and present time management realities, with fragmented and weak national and regional regulation on groundwater. Special attention is given to groundwater resources in irrigated agriculture, which increased use in all countries of the basin is due to quick access to underground resources and relatively good quality and quantity.  相似文献   

Asteroid identification at discovery     

Mikael Granvik  Karri Muinonen 《Icarus》2005,179(1):109-127

We present a novel method for the search of linkages among astrometric observations of asteroids, that is, tentative identifications among asteroids observed. Having two different master sets of asteroid observations each containing a number of separate subsets, we define a linkage as a pair of subsets residing in separate master sets that can be tied together with an orbit for given observational errors. To find linkages among a wealth of observations we use an efficient stepwise filtering approach. First, we start with what we call phase-space address comparison. The first step substantially reduces the initially huge amount of pairs by requiring that pairs to be subjected to further analysis have similar geocentric spherical coordinates at common epochs (for example, at three epochs). Second, we search for orbits for each of the selected pairs of subsets. Succeeding in the effort proves that a linkage exists. If there are contradictions among linkages found—for example, a single subset being linked to several mutually exclusive subsets—additional new or archive observations are usually needed to discard erroneous linkages. The new method is built on six-dimensional statistical orbital inversion (Ranging), and is therefore particularly suitable for analyzing objects with the shortest observational arcs, that is, newly discovered asteroids (and comets). Results from extensive and successful tests on simulated survey observations are presented and discussed. Theoretical and empirical scaling results show that the method is applicable to future large-scale surveys that will increase the rate of asteroid discovery by at least two orders of magnitude. The successful linking of faint single-night observation sets obtained with the Very Large Telescope are briefly reviewed.  相似文献