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21.
Balaji Rajagopalan Upmanu Lall David G. Tarboton 《Stochastic Environmental Research and Risk Assessment (SERRA)》1997,11(6):523-547
Kernel density estimators are useful building blocks for empirical statistical modeling of precipitation and other hydroclimatic
variables. Data driven estimates of the marginal probability density function of these variables (which may have discrete
or continuous arguments) provide a useful basis for Monte Carlo resampling and are also useful for posing and testing hypotheses
(e.g bimodality) as to the frequency distributions of the variable. In this paper, some issues related to the selection and
design of univariate kernel density estimators are reviewed. Some strategies for bandwidth and kernel selection are discussed
in an applied context and recommendations for parameter selection are offered. This paper complements the nonparametric wet/dry
spell resampling methodology presented in Lall et al. (1996). 相似文献
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G. Venkatesan V. Rajagopalan 《International Journal of Environmental Science and Technology》2016,13(4):1123-1130
Liners are commonly used in engineered waste disposal landfill to minimize the potential contamination of the aquatic environment. The adsorption behavior of Cu(II) from aqueous solution onto clay admixed with various mix ratios of quarry fines was investigated. The amount of Cu(II) adsorption increases with increase in contact time. The copper removal efficiencies of the composite mixture gradually decrease from 94.53 % (raw clay) to 85.59 % (20 % of quarry fines with clay), and appreciable decrease in percent removal 75.61 % was found with 25 % of quarry fines with clay. The kinetic adsorption data were analyzed by pseudo-first-order, pseudo-second-order, Bhattacharya–Venkobachar and Natarajan–Khalaf kinetic models to classify adsorption process mechanisms. Kinetic experimental data were good agreement with pseudo-second-order kinetic model with the degree of fitness of the data (R 2) 0.9999 for the adsorption of Cu(II). The results revealed that quarry fines can be used with optimum of 20 % replacement of natural clay for removal of Cu(II) as a liner material in landfills. 相似文献
24.
Statistical downscaling is based on the fact that the large-scale climatic state and regional/local physiographic features control the regional climate. In the present paper, a stochastic weather generator is applied to seasonal precipitation and temperature forecasts produced by the International Research Institute for Climate and Society(IRI). In conjunction with the GLM(generalized linear modeling) weather generator, a resampling scheme is used to translate the uncertainty in the seasonal forecasts(the IRI format only specifies probabilities for three categories: below normal, near normal, and above normal) into the corresponding uncertainty for the daily weather statistics. The method is able to generate potentially useful shifts in the probability distributions of seasonally aggregated precipitation and minimum and maximum temperature, as well as more meaningful daily weather statistics for crop yields, such as the number of dry days and the amount of precipitation on wet days. The approach is extended to the case of climate change scenarios, treating a hypothetical return to a previously observed drier regime in the Pampas. 相似文献
25.
Anoop A. Krishnan K.S. Yousuf P.L. Kumaran N. Harish B. Anoop V.V. Afsal M. Rajagopalan E. Vivekanandan P.K. Krishnakumar P. Jayasankar 《Estuarine, Coastal and Shelf Science》2008,76(4):909-913
The stomachs of 32 individuals of seven cetacean species incidentally caught in gill net and purseseine fisheries along Mangalore and Chennai coasts (India) between 2004 and 2006 were examined. The whole stomach (fore-gut, mid-gut and hind-gut) was examined in all cases. Prey remains (666 prey items comprising six species of teleosts, one crustacean and one squid species) were found in the stomachs of eight individuals (the remaining 24 stomachs were found to be empty). All cetaceans were found to feed mostly on teleosts with wide range of trophic levels. Based on an index that included frequency of occurrence, percentage by number and by weight, the oil sardine Sardinella longiceps was the main prey in the sample. Cetaceans appear to favour both pelagic as well as demersal prey, possibly indicating surface and benthic feeding habits. 相似文献
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Assimilation of snow covered area information into hydrologic and land-surface models 总被引：2，自引：0，他引：2
Martyn P. Clark Andrew G. Slater Andrew P. Barrett Lauren E. Hay Gregory J. McCabe Balaji Rajagopalan George H. Leavesley 《Advances in water resources》2006
This paper describes a data assimilation method that uses observations of snow covered area (SCA) to update hydrologic model states in a mountainous catchment in Colorado. The assimilation method uses SCA information as part of an ensemble Kalman filter to alter the sub-basin distribution of snow as well as the basin water balance. This method permits an optimal combination of model simulations and observations, as well as propagation of information across model states. Sensitivity experiments are conducted with a fairly simple snowpack/water-balance model to evaluate effects of the data assimilation scheme on simulations of streamflow. The assimilation of SCA information results in minor improvements in the accuracy of streamflow simulations near the end of the snowmelt season. The small effect from SCA assimilation is initially surprising. It can be explained both because a substantial portion of snowmelts before any bare ground is exposed, and because the transition from 100% to 0% snow coverage occurs fairly quickly. Both of these factors are basin-dependent. Satellite SCA information is expected to be most useful in basins where snow cover is ephemeral. The data assimilation strategy presented in this study improved the accuracy of the streamflow simulation, indicating that SCA is a useful source of independent information that can be used as part of an integrated data assimilation strategy. 相似文献
29.
V. Purnachandra Rao G. Rajagopalan K. H. Vora F. Almeida 《Journal of Earth System Science》2003,112(1):1-25
Relic carbonate deposits along the western margin of India occur as dolomite crusts, aragonite sands (pelletal / oolitic)
and aragonite-cemented limestones, oyster shells, corals, encrusted coralline algal and foraminiferal-dominated nodules. The
petrology and mineralogy of the deposits indicate that except for aragonite sands and foraminiferal nodules, the others were
formed in shallow marine conditions and serve as sea level indicators. Radiocarbon dates were measured for 62 relic deposits
covering the entire margin. The age of these deposits on the continental shelf off Cape Comorin and Mangalore, between 110
and 18 m depth, ranges between 12, 61014C yr BP and 6,39014C yr BP. On the northwestern margin of India, especially on the carbonate platform (between 64 and 100 m), the age ranges
from 17,250 to 6,73014C yr BP. The relic deposits of the Gulf of Kachchh at depths between 35 and 25 m are dated at 12,550–9,63014C yr BP. The age vs. depth plot of the relic deposits further indicates that the Gulf of Kachchh was inundated much early,
atleast by 15 ka, after the Last Glacial Maximum, and was subjected to uplift and subsidence during the Holocene. The carbonate
platform subsided during the early Holocene. Some of the relic deposits between Cape Comorin and Mangalore plot on or, closely
follow the glacio-eustatic sea level curve. Despite abundant siliciclastic flux discharged by the Narmada and Tapti during
the early Holocene, the platform off these rivers is largely devoid of this flux and carbonate sedimentation continued until
6,70014C yr BP. We suggest that the river-derived sediment flux diverted southwards under the influence of the SW monsoon current
and, thereby, increased the turbidity on the shelf and slope southeast of the carbonate platform and facilitated the formation
of deeper water foraminiferal nodules off Vengurla-Goa. 相似文献
30.
R. A. Antonia A. J. Chambers D. Phong-Anant S. Rajagopalan 《Boundary-Layer Meteorology》1979,17(1):101-118
A pair of parallel cold wires separated in either the vertical or lateral direction was used to obtain the three components x, y, z of the temperature derivative in the streamwise, lateral and vertical directions, respectively. The average absolute skewness values of x and z are nonzero and approximately equal, while the skewness of y is approximately zero. These results appear to be consistent with the presence of a large, three-dimensional organised structure in the surface layer. There is an apparent low-frequency contamination in the spectral density of y and z due mainly to small errors in estimating the sensitivity of the cold wires. The temperature derivatives were high-pass filtered, the filter being set to remove possible contributions from the large structure and to minimise low-frequency sensitivity contamination. The filtered rms ratios \~x/\~y and \~x/\~z were in the range 0.7 to 0.9, a result in qualitative agreement with that obtained in the laboratory boundary layer by Sreenivasan et al. (1977). The skewness of filtered x or z is negligible, consistent with local isotropy of small-scale temperature fluctuations and in support of the high wavenumber spectral isotropy discussed in Antonia and Chambers (1978). 相似文献