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1.
Prasun K. Gangopadhyay Freek van der Meer Paul van Dijk 《International Journal of Applied Earth Observation and Geoinformation》2009
Over the time-scale, earth's atmospheric CO2 concentration has varied and that is mostly determined by balance among the geochemical processes including burial of organic carbon in sediments, silicate rock weathering and volcanic activity. The best recorded atmospheric CO2 variability is derived from Vostok ice core that records last four glacial/interglacial cycles. The present CO2 concentration of earth's atmosphere has exceeded far that it was predicted from the ice core data. Other than rapid industrialization and urbanization since last century, geo-natural hazards such as volcanic activity, leakage from hydrocarbon reservoirs and spontaneous combustion of coal contribute a considerable amount of CO2 to the atmosphere. Spontaneous combustion of coal is common occurrence in most coal producing countries and sometimes it could be in an enormous scale. Remote sensing has already proved to be a significant tool in coalfire identification and monitoring studies. However, coalfire related CO2 quantification from remote sensing data has not endeavoured yet by scientific communities because of low spectral resolution of commercially available remote sensing data and relatively sparse CO2 plume than other geological hazards like volcanic activity. The present research has attempted two methods to identify the CO2 flux emitted from coalfires in a coalmining region in north China. Firstly, a band rationing method was used for column atmospheric retrieval of CO2 and secondly atmospheric models were simulated in fast atmospheric signature code (FASCOD) to understand the local radiation transport and then the model was implemented with the inputs from hyperspectral remote sensing data. It was observed that retrieval of columnar abundance of CO2 with the band rationing method is faster as less simulation required in FASCOD. Alternatively, the inversion model could retrieve CO2 concentration from a (certain) source because it excludes the uncertainties in the higher altitude. 相似文献
2.
This work presents a procedure for developing a high-resolution, regional climatology estimate, named RClimo, off the coast of central California. This high-resolution climatology may provide an alternative way to initialize numerical nowcast/forecast exercises in coastal regions. The methodology includes two primary steps: (1) averaging available data on a high-resolution grid and (2) objective interpolating the resulting average profiles onto a regular grid. The first step involves the computation of averages over density layers in the vertical and allowing for data gaps in the horizontal if data are unavailable at a high resolution. The OA in the second step uses anisotropic correlation length scales derived from the data themselves and an averaging radius to preserve the scales and variability of the synoptic fields. 相似文献
3.
Salt-water encroachment in the multi-layer groundwater system underlying the Bangkok metropolitan area was simulated with a quasi-three-dimensional flow and solute-transport model. The quasi-three-dimensional model used in this study is based on the model SUTRA. Accurate conceptualization of the initial state of the system with regard to the distribution of salt-water concentration is very important for modeling, especially in areas where localized zones of high salt concentration exist in the groundwater. Data adequacy and model results were evaluated by a geostatistical analysis. The model is capable of simulating the regional trend of potentiometric levels and salt concentration. However, lack of monitoring data in areas where localized zones of high salt concentration exist resulted in large model residuals. RÉSUMÉ: L'empiétement des eaux salées dans le système hydrologique multi-couche sous-jacent la zone métropolitaine de Bangkok a été simulé à l'aide d'un modèle quasi-tridimensionnel représentant l'écoulement des eaux et le transport d'éléments en solution. Le modèle quasi-tridimensionnel utilisé dans cette étude est basé sur le modèle SUTRA. Une conceptualisation exacte de l'état initial du système en ce qui concerne la répartition de la concentration des eaux salines est très important, particulièrement dans les endroits localisés où l'eau souterraine presente une forte concentration en sel. La qualité des donnés et des résultats a été estimée à l'aide d'une analyse géostatistique. Le modèle est capable de simuler la tendance régionale des niveaux potentiométriques et de la concentration en sel. Cependant, le manque de données de contrôle dans les endroits à forte concentration a donné lieu à des résiduels importants. RESUMEN: La intrusión de agua salina en el sistema multicapa bajo el área metropolitana de Bangkok se simuló mediante un modelo de flujo y transporte de solutos casi-tridimensional, basado en el modelo SUTRA. La conceptualizacián precisa de la distribución inicial de concentraciones de agua salina es muy importante para el modelo, especialmente en áreas donde existen zonas locales de alta concentración salina en el agua subterránea. La exactitud de los datos y del modelo se evaluaron mediante un análisis geoestadístico. El modelo permite simular la tendencia regional de los niveles piezométricos y la concentración de sales. Sin embargo, la falta de datos de muestreo en las zonas locales de alta salinidad resultaron en valores altos de los residuos calculados por el modelo. 相似文献
4.
The rocks of the Delhi Supergroup, which occur around Barr-Sendra and Phulad-Deogarh regions in Central Rajasthan, show three
phases of deformational episodes: (i) phase D1—tight-to-long limbed isoclinal fold (F1); phase D2—open, asymmetric fold (F
2) controlling the map pattern of the formational boundaries; and (iii) phase D3—major warps (F3). Interference between nearly coaxial F1 and F2 on northerly axes produced hook-shaped and crescent patterns whereas superimposition of easterly trending F3 on F2 produced dome-and-basin patterns. The thermal peak was achieved during the second phase of deformation when the rocks were
constructively metamorphozed and granites (850−750 m.y.), late synkinematic with respect to second phase of deformation, were
emplaced. The sequence of deformation and the structural pattern of the rocks of the Delhi Supergroup in Central Rajasthan
strikingly resemble those in northeastern Rajasthan. Structurally the characteristics of the Delhi Supergroup as verified
in the entire region from NE to Central Rajasthan are: (a) the same sequence of development of folds, F1, F2 and F3, interspersed with nearly identical phases of recrystallization, (b) hook-shaped interference pattern due to near-coaxial
refolding of F1 by F2, and (c) variation in axial plunge of F2 resulting in culminations and depressions. Lastly, phases of the recrystallization history indicates little time gap between
F1 and F2, and a considerable gap between F2 and F3. 相似文献
5.
6.
P. K. Gangopadhyay 《Journal of Earth System Science》1995,104(3):523-537
The Dating rocks and Darjeeling gneisses, which constitute the Sikkim dome in eastern Himalaya, as well as the Gondwana and
Buxa rocks of ‘Rangit Window’, disclose strikingly similar sequences of deformation and metamorphism. The structures in all
the rocks belong to two generations.
The structures of early generation are long-limbed, tight near-isoclinal folds which are often intrafolial and rootless. These
intrafolial folds are associated with co-planar tight folds with variably oriented axes and sheath folds with arcuate hinges.
Penetrative axial plane cleavage and mineral lineation are related structures; transposition of bedding is remarkable. This
early phase of deformation (D
1) is accompanied by constructive metamorphism. The structures of later generation are open, asymmetrical or polyclinal; a
crenulation cleavage or discrete fracture may occur. The structures of early generation are distorted by folds of later generation
and recrystallized minerals are cataclastically deformed. Recrystallization is meagre or absent during the later phase of
deformation (D
2).
The present discussion is on structures of early generation and strain environment during theD
1 phase of deformation. The concentration of intrafolial folds in the vicinity of ductile shear zones and decollement or detachment
surface (often described as ‘thrust’) may be considered in this context. The rocks of Darjeeling-Sikkim Himalaya display minor
structures other than intrafolial folds and variably oriented co-planar folds. The state of finite strain in the rocks, as
observed from features like flattened grains and pebbles, ptygmatic folds and boudinaged folds indicate combination of flattening
and constrictional type strain. The significance of the intrafolial folds in the same rocks is discussed to probe the environment
of strain during progressive deformation (D
1). 相似文献
7.
Dipak Sarkar S. K. Gangopadhyay A. K. Sahoo 《Journal of the Indian Society of Remote Sensing》2006,34(3):245-260
Visual interpretation of IRS ID LISS-III fused with PAN data (1:12,500 scale) ofPatloinala micro-watershed of Puruliya district, West Bengal was carried out for delineating the physiographic units based on the variations
in image characteristics. The major physiographic units identified were upland(Tanr), medium land(Baid), and low land(Bahal andKanali). The satellite remote sensing data coupled with ground truth were translated in terms of soils using composite interpretation
map as base. The abstraction level attained was phases of soil series based on Soil Taxonomy. On the basis of physiographic
variation and soil or soil site characteristics such as texture, depth, slope, erosion etc. the problem areas were identified
and land use plan has been suggested for the overall development of the micro-watershed. 相似文献
8.
Subhrendu?K.?PattanayakEmail author Bruce?A.?McCarl Allan?J.?Sommer Brian?C.?Murray Timothy?Bondelid Dhazn?Gillig Benjamin?DeAngelo 《Climatic change》2005,71(3):341-372
This study develops first-order estimates of water quality co-effects of terrestrial greenhouse gas (GHG) emission offset strategies in U.S. agriculture by linking a national level agricultural sector model (ASMGHG) to a national level water quality model (NWPCAM). The simulated policy scenario considers GHG mitigation incentive payments of $25 and $50 per tonne, carbon equivalent to landowners for reducing emissions or enhancing the sequestration of GHG through agricultural and land-use practices. ASMGHG projects that these GHG price incentives could induce widespread conversion of agricultural to forested lands, along with alteration of tillage practices, crop mix on land remaining in agriculture, and livestock management. This study focuses on changes in cropland use and management. The results indicate that through agricultural cropland about 60 to 70 million tonnes of carbon equivalent (MMTCE) emissions can be mitigated annually in the U.S. These responses also lead to a 2% increase in aggregate national water quality, with substantial variation across regions. Such GHG mitigation activities are found to reduce annual nitrogen loadings into the Gulf of Mexico by up to one half of the reduction goals established by the national Watershed Nutrient Task Force for addressing the hypoxia problem. 相似文献
9.
L. Calado I.C.A. da Silveira A. Gangopadhyay B.M. de Castro 《Continental Shelf Research》2010,30(10-11):1181-1188
The regional ocean off southeast Brazil (20°S–28°S) is known as a current-eddy-upwelling region. The proximity of the Brazil Current to the coast in the Cape São Tomé vicinities, as well as of its quasi-stationary unstable meanders, suggests the possibility of background eddy-induced upwelling. Such phenomenon can intensify the prevalent coastal upwelling due to wind and topographic effects. In this paper, with the help of a numerical simulation, we provide evidence that eddy-induced upwelling in the absence of wind is possible in this region. The simulation was conducted with a regional configuration of the 3-D Princeton Ocean Model initialized by a feature-based implementation of the Brazil Current and Cape Frio eddy, blended with climatology. 相似文献
10.