Convective aerosol fluxes near the ground surface     

E. B. Gledzer  I. G. Granberg  O. G. Chkhetiani 《Doklady Earth Sciences》2009,426(1):652-657

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On two small-scale circulation mechanisms of fine-aerosol transport in the atmospheric surface layer     

I. G. Granberg  M. S. Artamonova  E. M. Dobryshman 《Izvestiya Atmospheric and Oceanic Physics》2010,46(7):865-871

Small-scale processes are taken to mean the disturbances of the atmospheric basic background which are caused by the thermal inhomogeneity of the underlying surface and under which one can neglect the effects of both centripetal and Coriolis accelerations. Slight disturbances suggest the use of linearized hydrothermodynamic equations of a weakly compressible atmosphere. Two models are considered. In one of the models, circulation over a weakly sloping barchan is analyzed using a refined model of mountain—valley circulation (the well-known Prandtl model). The other model, which is a model of a thermal spot in a geostrophic flow, can conditionally be called “anticonvective.” This problem is solved using the method of universal functions for parabolic equations with variable coefficients.  相似文献   

Programme-objective approach and mathematical models in research of development perspectives for Siberia     

A.G. Aganbegyan  M.K. Bandman  A.G. Granberg 《Geoforum》1976,7(3):183-192

Economic geography has been enriched by modern scientific methods based on the ideas of systems analysis, optimisation, and economic-mathematical simulation. A system of models proposed by the Institute of Economics and Organisation of Industrial Production (IEOIP) of the Siberian Branch of the USSR Academy of Sciences has as its methodological basis the programme-objective approach. It is national economic criteria that are used for selection of optimum alternatives of interregional proportions, development of each region being appraised according to its contribution to development of national production. For each region, in accordance with the place occupied by it in the territorial division of labour, complex programmes are drawn up, situational analysis being used widely with different probabilities of particular events being taken into account. The system of models of the IEOIP reflects interactions of two hierarchic structures of the economy (production and territory), includes five subsystems (blocks), and covers three main echelons of national economic planning. Two blocks of spatial models are intended for optimisation of schemes of locating productive forces of the nation, particular regions, and parts thereof: territorial-production complexes (TPC), zones of complete assimilation and industrial centres. The optimisation problems of national economy spatial structure, of production and spatial structure of the economy of particular regions are solved in co-operation with national economic models, models of separate sectors and multi-sectoral complexes. The main tool for optimising spatial structure of the national economy and regions are various versions of the intersectoral interregional model and a group of models for optimising creation of TPCs. With the help of these models a series of practical problems has been solved at the IEOIP, the findings of which are a basis for some propositions relating to development of productive forces of the nation, of Siberia as a whole, of particular regions in 1975, 1990, and 2000.  相似文献   

Lake metabolism scales with lake morphometry and catchment conditions   总被引：1，自引：0，他引：1  

Peter?A.?StaehrEmail author  Lars?Baastrup-Spohr  Kaj?Sand-Jensen  Colin?Stedmon 《Aquatic Sciences - Research Across Boundaries》2012,74(1):155-169

We used a comparative data set for 25 lakes in Denmark sampled during summer to explore the influence of lake morphometry, catchment conditions, light availability and nutrient input on lake metabolism. We found that (1) gross primary production (GPP) and community respiration (R) decline with lake area, water depth and drainage ratio, and increase with algal biomass (Chl), dissolved organic carbon (DOC) and total phosphorus (TP); (2) all lakes, especially small with less incident light, and forest lakes with high DOC, have negative net ecosystem production (NEP < 0); (3) daily variability of GPP decreases with lake area and water depth as a consequence of lower input of nutrients and organic matter per unit water volume; (4) the influence of benthic processes on free water metabolic measures declines with increasing lake size; and (5) with increasing lake size, lake metabolism decreases significantly per unit water volume, while depth integrated areal rates remain more constant due to a combination of increased light and nutrient limitation. Overall, these meta-parameters have as many significant but usually weaker relationships to whole-lake and benthic metabolism as have TP, Chl and DOC that are directly linked to photosynthesis and respiration. Combining water depth and Chl to predict GPP, and water depth and DOC to predict R, lead to stronger multiple regression models accounting for 57–63% of the variability of metabolism among the 25 lakes. It is therefore important to consider differences in lake morphometry and catchment conditions when comparing metabolic responses of lakes to human impacts.  相似文献   

Improved prediction of vegetation composition in NW European softwater lakes by combining location,water and sediment chemistry     

Cristina?PulidoEmail author  Kaj?Sand-Jensen  Esther?C.?H.?E.?T.?Lucassen  Jan?G.?M.?Roelofs  Klaus?P.?Brodersen  Ole?Pedersen 《Aquatic Sciences - Research Across Boundaries》2012,74(2):351-360

Isoetids, as indicators of near-pristine softwater lakes, have a high priority in national and international (European Water Directive Framework) assessments of ecological lake quality. Our main goal was to identify the most important environmental factors that influence the composition of plant communities and specifically determine the presence and abundance of the isoetid Lobelia dortmanna in NW European softwater lakes. Geographical position and composition of surface water, porewater, sediment and plant communities were examined in 39 lakes in four regions (The Netherlands, Denmark, West Norway and East Norway) distributed over a 1,200-km long distance. We confirmed that lake location was accompanied by significant changes in environmental variables between NW European lakes. Lake location was the single most important determinant of vegetation composition and it had significant individual contributions independent of the coupling to environmental variables. This influence of location was supported by a significant decline of community similarity with geographical distance between pairs of lakes at regional, inter-regional and international scales. Combining the geographical position with environmental variables for surface water, porewater and sediment significantly improved prediction of vegetation composition. Specifically, the combination of latitude, surface water alkalinity, porewater phosphate and redox potential offered the highest correlation (BIO ENV correlation 0.66) to vegetation composition. This complex analysis can also account for high sediment variability in the littoral zone of individual lakes, by using site-specific physico-chemical sediment factors, and offer better predictions of vegetation composition when lake water chemistry is relatively homogeneous among lakes within regions.  相似文献   

Structure and evolution of the volcanic rift zone at Ponta de São Lourenço,eastern Madeira     

Andreas Klügel  Stefanie Schwarz  Paul van den Bogaard  Kaj A. Hoernle  Cora C. Wohlgemuth-Ueberwasser  Jana J. Köster 《Bulletin of Volcanology》2009,71(6):671-685

Ponta de São Lourenço is the deeply eroded eastern end of Madeira’s east–west trending rift zone, located near the geometric intersection of the Madeira rift axis with that of the Desertas Islands to the southeast. It dominantly consists of basaltic pyroclastic deposits from Strombolian and phreatomagmatic eruptions, lava flows, and a dike swarm. Main differences compared to highly productive rift zones such as in Hawai’i are a lower dike intensity (50–60 dikes/km) and the lack of a shallow magma reservoir or summit caldera. ⁴⁰Ar/³⁹Ar age determinations show that volcanic activity at Ponta de São Lourenço lasted from >5.2 to 4 Ma (early Madeira rift phase) and from 2.4 to 0.9 Ma (late Madeira rift phase), with a hiatus dividing the stratigraphy into lower and upper units. Toward the east, the distribution of eruptive centers becomes diffuse, and the rift axis bends to parallel the Desertas ridge. The bending may have resulted from mutual gravitational influence of the Madeira and Desertas volcanic edifices. We propose that Ponta de São Lourenço represents a type example for the interior of a fading rift arm on oceanic volcanoes, with modern analogues being the terminations of the rift zones at La Palma and El Hierro (Canary Islands). There is no evidence for Ponta de São Lourenço representing a former central volcano that interconnected and fed the Madeira and Desertas rifts. Our results suggest a subdivision of volcanic rift zones into (1) a highly productive endmember characterized by a central volcano with a shallow magma chamber feeding one or more rift arms, and (2) a less productive endmember characterized by rifts fed from deep-seated magma reservoirs rather than from a central volcano, as is the case for Ponta de São Lourenço.  相似文献   

六元体系Li-Na-K-Mg-Cl-SO₄-H₂O多温相平衡预测          下载免费PDF全文

崔瑞芝  聂国亮  李军  Kaj Thomsen  李武 《盐湖研究》2021,29(2):1-19, 28

采用基于扩展UNIQUAC模型的AQSOL027软件针对水盐体系Li-Na-K-Mg-Cl-SO_4-H_2O的六个五元子体系进行相平衡理论计算,首次报道了多个五元子体系在多个温度条件下的相图,将计算相图与已有实验相图以及基于其它热力学模型的计算相图进行了比较。结果表明:AQSOL027在相图计算中具有较好的准确性和可靠性。AQSOL027是一款基于Excel、用于计算复杂多温水—盐体系Li-Na-K-Mg-Ca-H-Cl-(HSO_4/SO_4)-(CO_2/HCO_3/CO_3)-(H_3BO_3/B_4O_7/BO_2)-OH-H_2O的计算机软件,集成了扩展UNIQUAC模型和相平衡算法,该软件可结合SysCAD和Aspen过程模拟器,实现盐田工艺过程的计算机辅助设计。  相似文献   

An emendation of elastic rebound theory: Main rupture and adjacent belt of right-lateral distortion detected by Viaduct at Kaynaşli, Turkey 12 November 1999 Düzce Earthquake     

Arvid M. Johnson  Kaj M. Johnson  Joe Durdella  Mete Sözen  Türel Gür 《Journal of Seismology》2002,6(3):329-346

The fault trace of the 12 November 1999 earthquake in theDüzce-Bolu region in Anatolia crossed the alignment of a 2.4 kmviaduct in Kaynali that had been carefully surveyed. The builders of theviaduct, the ASTALDI-BAYINDIR Co., resurveyed the viaduct after theearthquake. We repeated the survey for approximately one kilometre of theeastern end of the viaduct and obtained essentially identical results. Thoughit was unfortunate that the earthquake damaged the new structure, the piersdid produce a very rare record of ground deformation of an earthquake.In effect, the viaduct was a giant strain gage that yielded reliable data aboutground movement and distortion near a fault. This paper describes thesurvey data and their evaluation leading to convincing evidence that (a) thefault trace must be considered, not as a fault line or plane, but as a faultzone with a finite width and that (b) the structural damage within the zonewas caused, not primarily by ground acceleration, but by ground distortion.Along the right-lateral fault at Kaynali, the fault zone consists ofright-lateral movement at the main trace, a zone of right-lateral distortionnear the trace, bounded by left-lateral distortion. The 12 November 1999event in Turkey, like the ground deformation and fracturing at Landers,California (Johnson et al., 1994, 1996), thus affirmed a forgottenconclusion from the studies by Lawson (1908), Gilbert and Reid (1910)of the 1906 San Francisco earthquake that earthquake ruptures typicallyoccur throughout zones or belts, rather than along linear traces or planes.  相似文献   

Depth colonization of eelgrass (<Emphasis Type="Italic">Zostera marina</Emphasis>) and macroalgae as determined by water transparency in Danish coastal waters     

S?ren?Laurentius?NielsenEmail author  Kaj?Sand-Jensen  Jens?Borum  Ole?Geertz-Hansen 《Estuaries and Coasts》2002,25(5):1025-1032

We present a comparative analysis of lower depth limits for growth of eelgrass, large brown algae and other macroalgae measured by SCUBA-diving along 162 transects in 27 Danish fjords and coastal waters, coupled to 1,400 data series of water chemistry (especially nitrogen) and Secchi depth transparency collected between March and October. Danish coastal waters are heavily eutrophied and characterized by high particle concentrations, turbid water and lack of macrophyte growth in deep water. Median values are 3.6 m for Secchi depth and median lower-depth limits are 4.0 m for eelgrass, 5.3 m for brown algae and 5.0 m for other macroalgae. Depth limits for growth of eelgrass and macroalgae increase linearly with transparency in the coastal waters. The relationships are highly significant (p<10⁻⁶) and transparency accounts for about 60% of the variability of depth limits. Eelgrass extends approximately to half the maximum depth of macroalgae, presumably because of greater respiratory costs to maintain the below-ground rhizomes and roots of eelgrass, which often constitutes half the plant weight. As a reflection of the importance of total nitrogen (TN) in controlling phytoplankton biomass and thus Secchi depth in coastal marine waters, we found that TN could explain 48–73% of the variation in depth limits of eelgrass and macroalgae, according to a multiplicative model (Y=aX^b). As with Secchi depth, the relationship to eelgrass showed a lower slope, reflecting the higher respiratory costs of eelgrass. The models show great sensitivity and a profound quantitative response with proportional effects on Secchi depth and depth limits when total-N concentrations are reduced.  相似文献   

Constraining input and output fluxes of the southern-central Chile subduction zone: water,chlorine and sulfur     

David Völker  Heidi Wehrmann  Steffen Kutterolf  Karthik Iyer  Wolfgang Rabbel  Jacob Geersen  Kaj Hoernle 《International Journal of Earth Sciences》2014,103(7):2129-2153

In this paper, we constrain the input and output fluxes of H₂O, Cl and S into the southern-central Chilean subduction zone (31°S–46°S). We determine the input flux by calculating the amounts of water, chlorine and sulfur that are carried into the subduction zone in subducted sediments, igneous crust and hydrated lithospheric mantle. The applied models take into account that latitudinal variations in the subducting Nazca plate impact the crustal porosity and the degree of upper mantle serpentinization and thus water storage in the crust and mantle. In another step, we constrain the output fluxes of the subduction zone both to the subcontinental lithospheric mantle and to the atmosphere–geosphere–ocean by the combined use of gas flux determinations at the volcanic arc, volume calculations of volcanic rocks and the combination of mineralogical and geothermal models of the subduction zone. The calculations indicate that about 68 Tg/m/Ma of water enters the subduction zone, as averaged over its total length of 1,480 km. The volcanic output on the other hand accounts for 2 Tg/m/Ma or 3 % of that input. We presume that a large fraction of the volatiles that are captured within the subducting sediments (which accounts for roughly one-third of the input) are cycled back into the ocean through the forearc. This assumption is however questioned by the present lack of evidence for major venting systems of the submarine forearc. The largest part of the water that is carried into the subduction zone in the crust and hydrated mantle (accounting for two-thirds of the input) appears to be transported beyond the volcanic arc.  相似文献