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31.
Measurements of carbon dioxide (CO2) concentration were made at a coastal land station, Goa, on the west coast of India from March to June 2003 as part of the ARMEX (ARabian sea Monsoon Experiment) campaign. The observations show a systematic reduction (~120?mg?m?3) of CO2 concentration during the pre-monsoon months, March–May, during which no significant change in anthropogenic emissions takes place. CO2 shoots up from 520 to 635?mg?m?3 in June with the onset of the South West monsoon. Back trajectories show that the source of air mass gradually shifts from the coastal land mass to the open southern Arabian Sea during the pre-monsoon period. The observed reduction in CO2 is explained in terms of earlier measurements in the Arabian Sea indicating maximum chlorophyll a (Sarupria and Bhargava in J Mar Sci 27:292–297, 1998) and minimum partial pressure of CO2 (Sarma in J Geophys Res 108:3225, 2003) in the sea waters off the west coast of India during the pre-monsoon period, cleaner marine air mass advection from the open sea, and negligible local vertical CO2 flux. 相似文献
32.
Aeromagnetic anomalies over Bastar craton and Pranhita-Godavari (P-G) basin in the south of central India could be attributed
to NW-SE striking mafic intrusives in both the areas at variable depths. Such intrusions can be explained considering the
collision of the Bastar and Dharwar cratons by the end of the Archaean and the development of tensile regimes that followed
in the Paleoproterozoic, facilitating intrusions of mafic dykes into the continental crust. The P-G basin area, being a zone
of crustal weakness along the contact of the Bastar and Dharwar cratons, also experienced extensional tectonics. The inferred
remanent magnetization of these dykes dips upwards and it is such that the dykes are oriented towards the east of the magnetic
north at the time of their formation compared to their present NW-SE strike. Assuming that there was no imprint of magnetization
of a later date, it is concluded that the Indian plate was located in the southern hemisphere, either independently or as
part of a supercontinent, for some span of time during Paleoproterozoic and was involved in complex path of movement and rotation
subsequently. The paper presents a case study of the utility of aeromagnetic anomalies in qualitatively deducing the palaeopositions
of the landmasses from the interpreted remanent magnetism of buried intrusive bodies. 相似文献
33.
Magnetic anomalies of offshore Krishna-Godavari basin,eastern continental margin of India 总被引:1,自引:0,他引:1
K. V. Swamy I. V. Radhakrishna Murthy K. S. Krishna K. S. R. Murthy A. S. Subrahmanyam M. M. Malleswara Rao 《Journal of Earth System Science》2009,118(4):405-412
The marine magnetic data acquired from offshore Krishna-Godavari (K-G) basin, eastern continental margin of India (ECMI),
brought out a prominent NE-SW trending feature, which could be explained by a buried structural high formed by volcanic activity.
The magnetic anomaly feature is also associated with a distinct negative gravity anomaly similar to the one associated with
85°E Ridge. The gravity low could be attributed to a flexure at the Moho boundary, which could in turn be filled with the
volcanic material. Inversion of the magnetic and gravity anomalies was also carried out to establish the similarity of anomalies
of the two geological features (structural high on the margin and the 85°E Ridge) and their interpretations. In both cases,
the magnetic anomalies were caused dominantly by the magnetization contrast between the volcanic material and the surrounding
oceanic crust, whereas the low gravity anomalies are by the flexures of the order of 3–4 km at Moho boundary beneath them.
The analysis suggests that both structural high present in offshore Krishna-Godavari basin and the 85°E Ridge have been emplaced
on relatively older oceanic crust by a common volcanic process, but at discrete times, and that several of the gravity lows
in the Bay of Bengal can be attributed to flexures on the Moho, each created due to the load of volcanic material. 相似文献
34.
Theoretical approaches are of fundamental importance to predict the potential impact of waste disposal facilities on ground water contamination. Appropriate design parameters are generally estimated by fitting theoretical models to data gathered from field monitoring or laboratory experiments. Transient through-diffusion tests are generally conducted in the laboratory to estimate the mass transport parameters of the proposed barrier material. These parameters are usually estimated either by approximate eye-fitting calibration or by combining the solution of the direct problem with any available gradient-based techniques. In this work, an automated, gradient-free solver is developed to estimate the mass transport parameters of a transient through-diffusion model. The proposed inverse model uses a particle swarm optimization (PSO) algorithm that is based on the social behavior of animals searching for food sources. The finite difference numerical solution of the forward model is integrated with the PSO algorithm to solve the inverse problem of parameter estimation. The working principle of the new solver is demonstrated and mass transport parameters are estimated from laboratory through-diffusion experimental data. An inverse model based on the standard gradient-based technique is formulated to compare with the proposed solver. A detailed comparative study is carried out between conventional methods and the proposed solver. The present automated technique is found to be very efficient and robust. The mass transport parameters are obtained with great precision. 相似文献
35.
36.
The aim of this short note is to test whether the morphological skeletal network (MSN) of water bodies that resembles a river network follows Horton's laws. A fractal relationship of MSN of a water body is also shown. This investigation shows that the MSN of the Nizamsagar reservoir follows Horton's laws. Furthermore, this reservoir has a fractal dimension (D
m) of 1.92 which was computed by using two morphometric quantities and the fractal dimension of the main skeletal length (d). This value tallies exactly with the fractal dimension (D
f) of the whole MSN computed through box-counting method. 相似文献
37.
The aim of this short note is to test whether the morphological skeletal network (MSN) of water bodies that resembles a river network follows Horton's laws. A fractal relationship of MSN of a water body is also shown. This investigation shows that the MSN of the Nizamsagar reservoir follows Horton's laws. Furthermore, this reservoir has a fractal dimension (D m) of 1.92 which was computed by using two morphometric quantities and the fractal dimension of the main skeletal length (d). This value tallies exactly with the fractal dimension (D f) of the whole MSN computed through box-counting method. 相似文献
38.
39.
Raghavendra Vishnu Tadivaka Bhanu Priyanka Paruchuri Sridhar Miriyala Padma Raju Koppireddi Venkata Ratnam Devanaboyina 《Acta Geophysica》2017,65(4):777-784
The performance and measurement accuracy of global navigation satellite system (GNSS) receivers is greatly affected by ionospheric scintillations. Rapid amplitude and phase variations in the received GPS signal, known as ionospheric scintillation, affects the tracking of signals by GNSS receivers. Hence, there is a need to investigate the monitoring of various activities of the ionosphere and to develop a novel approach for mitigation of ionospheric scintillation effects. A method based on Local Mean Decomposition (LMD)–Detrended Fluctuation Analysis (DFA) has been proposed. The GNSS data recorded at Koneru Lakshmaiah (K L) University, Guntur, India were considered for analysis. The carrier to noise ratio (C/N0) of GNSS satellite vehicles were decomposed into several product functions (PF) using LMD to extract the intrinsic features in the signal. Scintillation noise was removed by the DFA algorithm by selecting a suitable threshold. It was observed that the performance of the proposed LMD–DFA was better than that of empirical mode decomposition (EMD)–DFA. 相似文献
40.