Effect of Secondary Circulations on the Surface–Atmosphere Exchange of Energy at an Isolated Semi-arid Forest     

Konstantin Kröniger  Frederik De Roo  Peter Brugger  Sadiq Huq  Tirtha Banerjee  Judith Zinsser  Eyal Rotenberg  Dan Yakir  Shani Rohatyn  Matthias Mauder 《Boundary-Layer Meteorology》2018,169(2):209-232

Afforestation in semi-arid regions can potentially enhance the global carbon sink by increasing the terrestrial biomass. However, the survival of planted forests under such extreme environmental conditions is not guaranteed a priori, and critically depends on the surface–atmosphere exchange of energy. We investigate the pine forest Yatir in Israel, an example of a man-made semi-arid ecosystem, by means of large-eddy simulations. We focus on the interaction between surface–atmosphere exchange and secondary circulations that couple the isolated forest to the surrounding shrubland. The large-eddy simulations feature a grid resolution that resolves the forest canopy in several layers, and are initialized by satellite data and Doppler lidar, eddy-covariance and radiosonde measurements. We perform three large-eddy simulations with different geostrophic wind speeds to investigate the influence of those wind speeds on the surface–atmosphere exchange. We reproduce the measured mean updrafts above the forest and mean downdrafts above the shrubland, which increase in strength with decreasing geostrophic wind speed. The largest updrafts emerge above the older, denser part of the forest, triggering secondary circulations. The spatial extent of these circulations does not cover the entire forest area, although we observe a reduced aerodynamic resistance in the regions of updraft. Our simulations indicate that the enhanced surface–atmosphere exchange of the Yatir forest is not sufficient to compensate for the increased net radiation, due to the lower albedo of the forest with respect to the surroundings, resulting in higher air temperatures inside the forest. However, the difference between the forest and shrubland temperatures decreases with increasing geostrophic wind speed due to reduction in the aerodynamic resistance.  相似文献   

Timescales of storage and recycling of crystal mush at Krafla Volcano,Iceland     

Kari M. Cooper  Kenneth W. W. Sims  John M. Eiler  Neil Banerjee 《Contributions to Mineralogy and Petrology》2016,171(6):54

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A Novel Semi-Supervised Land Cover Classification Technique of Remotely Sensed Images     

Biplab Banerjee  Krishna Mohan Buddhiraju 《Journal of the Indian Society of Remote Sensing》2015,43(4):719-728

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<Emphasis Type="Italic">Nummulites solitarius — Nummulites burdigalensis</Emphasis> lineage in Kutch with remarks on the age of Naredi Formation     

Pratul Kumar Saraswati  Urbashi Sarkar  Santanu Banerjee 《Journal of the Geological Society of India》2012,79(5):476-482

Three successive subspecies of Nummulites burdigalensis evolved from N. solitarius. These include N. burdigalensis keupperi, N. burdigalensis burdigalensis and N. burdigalensis cantabricus. The evolving lineage is traced in a borehole drilled through the Naredi Formation of Kutch. The associated taxa include N. solitarius and N. fraasi in the lower part and Assilina laxispira and A. spinosa in the upper part of the formation. The better stratigraphic resolution achieved by subspecies identification and the lately redefined Ilerdien Stage in the background of Early Eocene carbon isotope excursion marker, lead to constrain the age of Naredi Formation as Early Eocene, ranging from shallow-benthic zones SBZ6 to SBZ11.  相似文献   

Commercial steel wool for reduction of hexavalent chromium in wastewater: batch kinetic studies and rate model     

P. Mitra  P. Banerjee  D. Sarkar  S. Chakrabarti 《International Journal of Environmental Science and Technology》2014,11(2):449-460

The present study aims at searching the potential of commercial grade steel wool in reducing hexavalent chromium in aqueous phase under batch mode. About 30 % of the initial hexavalent chromium was found to reduce within 2 h at a pH of 3. However, on testing the combined effects of different process parameters, namely the solution pH, wool loading, etc., the optimum batch parametric condition has been fixed. A moving boundary type kinetic model, which takes into account the effect of passivation along with the direct reduction mechanism to simulate the gross uptake profile of Cr(VI) from the bulk solution is proposed. The effective pore diffusivity of Cr(VI) in commercial steel wool was determined by a suitable global optimization technique. Additionally, the model is also capable to simulate the decline of active external surface area of the wool caused by passivation with time. A good match of the experimental data and model-simulated transient bulk concentration of Cr(VI) (under optimum parametric condition only) establishes the general validity of the proposed model.  相似文献   

Pillow lavas as a habitat for microbial life     

Harald Furnes  Neil R. Banerjee  Hubert Staudigel  & Karlis Muehlenbachs 《Geology Today》2007,23(4):143-146

The upper oceanic crust consists predominantly of pillow lavas that, soon after their eruption, are colonized by microbes when the ambient temperature ameliorates. During the process of microbial interaction with the glassy rims of pillows several types of bio-traces are generated, of which micro-textures are the most spectacular. Microbial textures are most useful for mapping the depth of the oceanic biosphere, and in the search for the earliest life on Earth.  相似文献   

Mean Flow Near Edges and Within Cavities Situated Inside Dense Canopies   总被引：3，自引：3，他引：0  

Tirtha Banerjee  Gabriel Katul  Stefano Fontan  Davide Poggi  Mukesh Kumar 《Boundary-Layer Meteorology》2013,149(1):19-41

A streamfunction-vorticity formulation is used to explore the extent to which turbulent and turbulently inviscid solutions to the mean momentum balance explain the mean flow across forest edges and within cavities situated inside dense forested canopies. The turbulent solution is based on the mean momentum balance where first-order closure principles are used to model turbulent stresses. The turbulently inviscid solution retains all the key terms in the mean momentum balance but for the turbulent stress gradients. Both exit and entry versions of the forest edge problem are explored. The turbulent solution is found to describe sufficiently the bulk spatial patterns of the mean flow near the edge including signatures of different length scales reported in canopy transition studies. Next, the ‘clearing inside canopy’ or the so-called ‘cavity’ problem is solved for the inviscid and turbulent solutions and then compared against flume experiments. The inviscid solution describes the bulk flow dynamics in much of the zones within the cavity. In particular, the solution can capture the correct position of the bulk recirculation zone within the cavity, although with a weaker magnitude. The inviscid solution cannot capture the large vertical heterogeneity in the mean velocity above the canopy, as expected. These features are better captured via the first-order closure representation of the turbulent solution. Given the ability of this vorticity formulation to capture the mean pressure variations and the mean advective acceleration terms, it is ideal for exploring the distributions of scalars and roughness-induced flow adjustments on complex topography.  相似文献   

On the solution of steady unconfined seepage towards semi-infinite slopes     

Angel Muleshkov  Sunirmal Banerjee 《国际地质力学数值与分析法杂志》1991,15(4):271-288

Analytical solutions for the two-dimensional problem of unconfined seepage towards semi-infinite slopes are described. The analysis employs complex variable techniques. Conformal mappings have been used to reduce the problem to solving an ordinary differential equation. The resulting integrals are presented in terms of special functions. The solutions for the location of the phreatic surface and the exit point have been obtained in parametric form. Some additional results and asymptotic expansions of the solutions are also presented. The numerical results have been calculated and plotted for different values of the slope angle in dimensionless co-ordinate space.  相似文献   

Investigation of biological, chemical and physical processes on and in planetary surfaces by laboratory simulation     

D.W.G Sears  P.H Benoit  S.W.S McKeever  D Banerjee  T Kral  W Stites  L Roe  P Jansma  G Mattioli 《Planetary and Space Science》2002,50(9):821-828

The recently established Arkansas-Oklahoma Center for Space and Planetary Science has been given a large planetary simulation chamber by the Jet Propulsion Laboratory, Pasadena, California. When completely refurbished, the chamber will be dubbed Andromeda and it will enable conditions in space, on asteroids, on comet nuclei, and on Mars, to be reproduced on the meter-scale and surface and subsurface processes monitored using a range of analytical instruments. The following projects are currently planned for the facility. (1) Examination of the role of surface and subsurface processes on small bodies in the formation of meteorites. (2) Development of in situ sediment dating instrumentation for Mars. (3) Studies of the survivability of methanogenic microorganisms under conditions resembling the subsurface of Mars to test the feasibility of such species surviving on Mars and identify the characteristics of the species most likely to be present on Mars. (4) The nature of the biochemical “fingerprints” likely to have been left by live organisms on Mars from a study of degradation products of biologically related molecules. (5) Testing local resource utilization in spacecraft design. (6) Characterization of surface effects on reflectivity spectra for comparison with the data from spacecraft-borne instruments on Mars orbiters.  相似文献   

A high-resolution Fabry-Pérot spectrometer for emission line studies in planetary nebulae and other extended astronomical objects     

D. P. K. Banerjee  B. G. Anandarao  J. N. Desai  N. S. Jog  P. K. Kikani  R. K. Mahadkar  K. S. B. Manian  F. M. Pathan  N. C. Shah  M. Thomas 《Astrophysics and Space Science》1987,139(2):327-335

We describe here a scanning piezo-electric Fabry-Pérot spectrometer operating in the photoncounting mode whose plate spacing and parallelism are maintained by a servo-controlled system, ensuring high accuracy, for the study of emission lines from extended astronomical objects in the spectral range 4500–7000 Å. Details of the optical set-up and the Data Acquisition System (DAS) are described. Its performance at the Cassegrain focus of the 1 m telescope at Kavalur is discussed. Some line profiles on planetary nebulae studied with the above spectrometer are also presented.  相似文献