Comparison of TOPEX/POSEIDON Altimeter Derived Wind Speed and Wave Parameters with Ocean Buoy Data in the North Indian Ocean   总被引：1，自引：0，他引：1  

Jignesh Kshatriya  Abhijit Sarkar  Raj Kumar 《Marine Geodesy》2001,24(3):131-138

Results of comparison exercises carried out between the state-of-the-art TOPEX/POSEIDON altimeter-derived ocean surface wind speed and ocean wave parameters (significant wave height and wave period) and those measured by a set of ocean data buoys in the North Indian Ocean are presented in this article. Altimeter-derived significant wave height values exhibited rms deviation as small as ±0.3 m, and surface wind speed of ±1.6 m/s. These results are found consistent with those found for the Pacific Ocean. For estimation of ocean wave period, the spectral moments-based semiempirical approach, earlier applied on GEOSAT data, was extended to TOPEX/POSEIDON. For this purpose, distributions of first four years of TOPEX/POSEIDON altimeter data and climatology over the North Indian Ocean were analyzed and a new set of coefficients generated for estimation of wave period. It is shown that wave periods thus estimated from TOPEX/POSEIDON data (for the subsequent two years), when compared with independent data set of ocean data buoys deployed in the North Indian Ocean, exhibit improved accuracy (rms ~ ±1.4 nos) over those determined earlier with GEOSAT data.  相似文献   

Geostatistical analysis of arsenic concentration in the groundwater of Malda district of West Bengal, India     

Barendra Purkait  Amitava Mukherjee 《Frontiers of Earth Science》2008,2(3):292-301

The problem of arsenic (As) poisoning in the upper deltaic plain of the Ganga-Bhagirathi river system in the Bengal Basin of West Bengal, India is an alarming issue. Four blocks (Kaliachak-1, 2, 3 and English Bazar) of Malda district, West Bengal were critically studied. Geomorphologically, the area exhibits three terraces: the present Youngest terrace (T₀-terrace), the Older Shaugaon Surface (T₁-terrace) and the Oldest Baikunthapur Surface (T₂-terrace). On the basis of numerous measurements, including As-content, pH, DO, specific conductivity and salinity, it was observed that maximum As-content beyond the permissible limit (0.05 mg/L, Indian standard) occurs within a depth range of 10–30 m with a non-linear distribution pattern. Variance test also found that a block effect was highly significant in an As-distribution pattern. Mean arsenic level of Kaliachak block-1 is 0.2253 mg/L, followed by Kaliachak-2 with arsenic level 0.1923, Kaliachak-3 with arsenic level 0.1755 and English Bazar with arsenic level 0.1324. The arsenious belt lies mainly within the Older terrace (T₁). The very recent flood plain deposits of silvery white, fine sands lying very close to the Ganga River margin do not contain significant amounts of As. Elevated As-concentration in the ground water was observed in alluvial sands, grayish white to brownish in color and occurring away from the Ganga margin. The Oldest terrace (T2) further away from the Ganga margin (e.g. English Bazar) and Barind surface contains less arsenic. Barind surface acts as a hard capping with ferruginous sands and lateritic concretions-chocolate, mottled and purple brown in color-occurring northeast of the studied area. Arsenic content of ground water in the same locality within a radius of ∼ 20 m varies within wide limits. Thus, it poses problem to delineate its distribution pattern. Such a patchy occurrence possibly could not be explained satisfactorily solely by geomorphology. Chemical analysis of aquifer clay samples of the cores shows a maximum Ascontent of up to 3 mg/kg, whereas the bulk samples (sandclay mixture) of the cores contain a maximum of 17 mg/kg As-value. Therefore, it is not always true that clay contains elevated As-value.  相似文献   

Guided wave propagation in a moving magnetized plasma bounded by parallel perfectly conducting planes     

Pradeep K. Mukherjee 《Astrophysics and Space Science》1976,41(1):97-104

The structure of the Saturnian rings is compared with the asteroidal belt and the relative importance of the resonance effects and the cosmogonic effects is evaluated. No visible correspondence to the Kirkwood gaps is expected theoretically, nor is there any observational evidence for such effects. The only possible resonance is the 1:1 resonance with Saturn's spin period.Cosmogonic shadow effects are responsible for the main features of the ring structure, including Cassini's division, the limit between the B and C ring, and possibly also Guérin's division.  相似文献   

Significance of transition between Talchir Formation and Karharbari Formation in Lower Gondwana basin evolution — A study in West Bokaro Coal basin, Jharkhand, India     

H. N. Bhattacharya  Abhijit Chakraborty  Biplab Bhattacharya 《Journal of Earth System Science》2005,114(3):275-286

Basal part of the Gondwana Supergroup represented by Talchir and Karharbari Formations (Permo-Carboniferous) records an abrupt change-over from glacio-marine to terrestrial fluviolacustrine depositional environment. The contact between the two is an unconformity. Facies analysis of the glacio-marine Talchir Formation reveals that basal glaciogenic and reworked glaciogenic sediments are buried under storm influenced inner and outer shelf sediments. Facies associations of the Karharbari Formation suggest deposition as fluvio-lacustrine deposits in fault-controlled troughs. An attempt has been made in this paper to explain the sedimentation pattern in Talchir and Karharbari basins, and the abrupt change-over from glacio-marine to terrestrial fluviolacustrine depositional environment in terms of glacio-isostacy.  相似文献   

Hydro-climatic hazards for crops and cropping system in the chars of the Jamuna River and potential adaptation options     

M. Shahjahan Mondal  M. Aminur Rahman  Nandan Mukherjee  Hamidul Huq  Rezaur Rahman 《Natural Hazards》2015,76(3):1431-1455

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Potential of SAR intensity tracking technique to estimate displacement rate in a landslide-prone area in Haridwar region,India     

Atanu Bhattacharya  Kriti Mukherjee  Manoj Kuri  Malte Vöge  M. L. Sharma  M. K. Arora  Rejinder K. Bhasin 《Natural Hazards》2015,79(3):2101-2121

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Investigation of dominant modes of monsoon ISO in the northwest and eastern Himalayan region     

Sandipan Mukherjee  Srabanti Ballav  Sandeep Soni  Kireet Kumar  Utpal Kumar De 《Theoretical and Applied Climatology》2016,125(3-4):489-498

This study investigates the altitudinal variation of dominant modes of summer monsoon intra-seasonal oscillation (ISO) over the Northwest (NWH) and Eastern Himalayan (EH) region using (i) spatially scattered 133 number of station rainfall observations and (ii) latitudinal transect-wise (LT) rainfall variation, obtained from an observed interpolated gridded rainfall data for the period 1995–2004. The altitudinal variation of dominant modes of monsoon ISO were investigated by exploring the strong and weak phases of the principal components of 10–90 days bandpass rainfall data of June to September with respect to location specific station height. Investigation of frequency of days for light and moderate rainfall along with the occurrence of total seasonal rainy days has revealed existence of a rainfall maximum around 2100 m height for the NWH region. Similarly, the total seasonal rainy days of EH region was found to have maxima between 1100 and 1400 m height. Analyses of the spatially scattered station rainfall observation for the NWH region showed that the strong periods of ISO modes exist around 747.9 (±131.7) m and 2227.2 (±100.2) m heights. Over the EH region, the dominant modes of the monsoon ISO were found to be centred around 1200 m. Significant alterations of strong and weak phases of monsoon ISO as a response to altitudinal variation in the mountain surface were observed when latitudinal transect-wise variation of monsoon ISO modes were investigated.  相似文献   

The Air-Coastal Sea Chemical Exchange: A Case Study on the New Jersey Coast     

Yuan Gao  Pami Mukherjee  Rafael Jusino-Atresino 《Aquatic Geochemistry》2016,22(4):275-289

The coastal marine atmosphere adjacent to large urban and industrial centers is in general strongly impacted by pollution emissions, resulting in high loading of pollutants in the ambient air. Among the airborne substances are certain trace elements from a variety of emission sources that can serve as micronutrients to marine organisms in coastal waters. High concentrations of such elements in coastal air can result in enhanced air-to-sea deposition fluxes to coastal waters. They could also be transported over the open ocean, affecting the composition of the remote marine atmosphere and then ocean ecosystems. To provide better understanding of the extent of air-to-sea deposition processes on the New Jersey coast, a heavily polluted coastal region on the US East Coast, a synthesis of observation data was carried out for selected trace elements, including Fe, Cd, Cr and Cu, derived from measurements of both size-segregated and bulk aerosol particles, as well as precipitation around the New Jersey coast. The atmospheric input of Hg was also estimated based on measurement data. Results indicated that the total deposition fluxes of most trace elements were higher in Northern coastal NJ compared to Southern coastal NJ, reflecting the differences in the source strengths of these element emissions between the two coastal regions. Dry deposition processes were more significant for common dust-derived elements, particularly Fe and Al, compared with their wet deposition fluxes. However, the processes of precipitation scavenging appeared to be more important for the elements that were often enriched in fine particles including Zn, Cu, Pb and Ni. The removal of Hg from the ambient air was overwhelmingly dominated by atmospheric wet deposition. In the future, atmospheric measurements at more sites on the NJ coast should be performed simultaneously to reduce the spatial and temporal uncertainties associated with atmospheric deposition fluxes estimated in this study.  相似文献   

Kinematics and shear heat pattern of ductile simple shear zones with ‘slip boundary condition’     

Kieran F. Mulchrone  Soumyajit Mukherjee 《International Journal of Earth Sciences》2016,105(3):1015-1020

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Deformation behavior of migmatites: insights from microstructural analysis of a garnet–sillimanite–mullite–quartz–feldspar-bearing anatectic migmatite at Rampura–Agucha,Aravalli–Delhi Fold Belt,NW India     

Prakash  Abhishek  Piazolo  Sandra  Saha  Lopamudra  Bhattacharya  Abhijit  Pal  Durgesh Kumar  Sarkar  Saheli 《International Journal of Earth Sciences》2018,107(6):2265-2292

International Journal of Earth Sciences - In the present study we investigate the microstructural development in mullite, quartz and garnet in an anatectic migmatite hosted within a Grenvillian-age...  相似文献