An Experiment Using the High Resolution Eta and WRF Models to Forecast Heavy Precipitation over India   总被引：1，自引：0，他引：1  

Y. V. Rama Rao  H. R. Hatwar  Ahmad Kamal Salah  Y. Sudhakar 《Pure and Applied Geophysics》2007,164(8-9):1593-1615

In the present study using the Weather Research and Forecasting (WRF) and Eta models, recent heavy rainfall events that occurred (i) over parts of Maharastra during 26 to 27 July, 2005, (ii) over coastal Tamilnadu and south coastal Andhra Pradesh during 24 to 28 October, 2005, and (iii) the tropical cyclone of 30 September to 3 October, 2004/Monsoon Depression of 2 to 5 October 2004, that developed during the withdrawal phase of the southwest monsoon season of 2004 have been investigated. Also sensitivity experiments have been conducted with the WRF model to test the impact of microphysical and cumulus parameterization schemes in capturing the extreme weather events. The results show that the WRF model with the microphysical process and cumulus parameterization schemes of Ferrier et al. and Betts-Miller-Janjic was able to capture the heavy rainfall events better than the other schemes. It is also observed that the WRF model was able to predict mesoscale rainfall more realistically in comparison to the Eta model of the same resolution.  相似文献   

Hydrogeologic Units Of Lebanon     

Kamal Khair  Nizar Aker  Khalil Zahruddine 《Hydrogeology Journal》1992,1(2):34-49

Based on geomorphologic and hydrogeologic characteristics of its territory, Lebanon is divided into three provinces: the West Lebanon province, the Bekaa province, and the East Anti-Lebanon province. These provinces are subdivided into smaller hydrogeologic units, the basins and subbasins. Significant features used in the subdivision are faults, relief, anticlinal axes, river channels, and water divides. Recharge to groundwater is a percentage of the intake area, the percipitation rate over this area, and the infiltration rate of outcropping rocks. The amounts of recharged water over the three provinces are 1609, 914, and 19 Mm³, respectively. Discharge is surface water from springs and water wells along the Lebanese coast. The discharge from the Lebanese rivers exceeds 3700 Mm³/year, an appreciable amount of which comes from natural springs. The quantity of groundwater pumped by wells or flowing into neighboring countries and to the sea as submarine springs, may exceed 800 Mm³/year.  相似文献   

Effects of couple-stresses in the semi-infinite viscoelastic medium due to time dependent loading     

Giriraj Tiwari 《Pure and Applied Geophysics》1971,88(1):29-34

Summary Effects of couple-stresses on shear stresses in the semi-infinite viscoelastic medium are investigated. Numerical results are obtained.  相似文献   

Magmatic differentiation of the volcanics at Pavagarh,Gujarat, India     

B. D. Tiwari 《Bulletin of Volcanology》1971,35(4):1129-1177

Magmatic differentiation in Pavagarh adopted the courses corresponding to the olivine-basalt trend including olivine-basalt, mugearite, latite and pitch-stone and the normal basalt trend comprising tholeiitic basalts, andesite, dellenite, and rhyolite. The dellenite-rhyolite assemblage is not consanguineous. Their average composition corresponds with the petrochemical field of the basalt-andesite-dacite-rhyolite association or the calc-alkaline series of Nockolds. It lies in between plateau and tholeiitic basalts of different provinces and shows alkali enrichment in the initial phases of differentiation. The main factors governing the nature and course of differentiation are the changing concentration of the volatiles during different phases of magmatic activity, the different composition of the liquid during the successive phases of its eruption and the partial assimilation of the siliceous rocks forming the platform over which the present volcanics were laid down. Other factors are crystal settling (ankaramites), reaction of the early-formed crystals with the remaining magma (olivine-basalt) and mixing of the magmatic liquids belonging to different phases (mugearites). The chronological history of the magmatic activity in relation to the geological setting of the area shows that the rocks belong to a single parent magma closely akin to olivine-basalt or plateu basalt magma type which through differentiation into two lines of descent, has given rise to the present volcanic assemblage.  相似文献   

Geochemical Aspects of Hypogene Hydrothermal Alteration Zones in the Chol-qeshlaghi Area, NW Iran: Constrains on REEs     

Kamal SIAHCHESHM  Mohammad SHAHSAVANI BAMI 《《地质学报》英文版》2020,94(3):777-788

Chol-qeshlaghi altered area lies in the northwestern part of the post-collisional Urumieh-Dokhtar magmatic arc, NW Iran. Pervasive silicic, argillic, phyllic and propylitic altered zones appears to be intimately affiliated to the fluids derivative of upper Oligocene Khankandi granodiorite. This paper is dedicated to the identification of geochemical characteristics of hydrothermal alterations, focusing on the determination of the mass gains and losses of REEs, to gain significant insights regarding the chemical exchanges prevailed between the host rocks and hydrothermal fluids. The low pH and high activity of SO_4~(-2) ligands in silicic alteration fluids, resulting in depletion of entire REEs. Decreasing of LREEs appeared in argillic zone may attributed to reduce in adsorption ability of clay minerals in low pH; whereas HREEs enrichment in phyllic zone was inclined to put it down to the abundance of sericite(± Fe oxides). A significant reduction of Eu/Eu* ratio in silicic zone can be attributed to negligible sulfides and clay minerals as some effective agents in adsorption of released Eu~(+2). Factors such as changes in pH, the abundance of absorptive neomorph mineral phases, activity of ligands play an important role in controlling the distribution and concentration of REEs in Chol-qeshlaghi alteration system.  相似文献   

The isotopic composition of carbon in the Alberta oil sand     

Kamal N. Jha  John Gray  Otto P. Strausz 《Geochimica et cosmochimica acta》1979,43(9):1571-1573

The carbon isotopic ratios obtained from Athabasca bitumen, asphaltene and maltene have the same value $\text{δ}{}^{13}\text{C}\text{= ?29.6}\text{per ml}$. The corresponding values in the Cold Lake deposits are ?30.6, ?30.0 and ?31.6 per ml. The ratios determined for methane collected from the oil sand and its fractions are about 15 per ml lower than the above values. It appears that the Athabasca and Cold Lake Reservoirs have similar histories.  相似文献   

Grace estimates of water mass loss from northern Indian region     

V. M. Tiwari  John Wahr 《Journal of the Geological Society of India》2011,78(3):279-280

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Probing Statistical Isotropy of Cosmological Radio Sources using Square Kilometre Array     

Shamik Ghosh  Pankaj Jain  Gopal Kashyap  Rahul Kothari  Sharvari Nadkarni-Ghosh  Prabhakar Tiwari 《Journal of Astrophysics and Astronomy》2016,37(4):25

There currently exist many observations which are not consistent with the cosmological principle. We review these observations with a particular emphasis on those relevant for the Square Kilometre Array (SKA). In particular, several different data sets indicate a preferred direction pointing approximately towards the Virgo cluster. We also observe a hemispherical anisotropy in the Cosmic Microwave Background radiation (CMB) temperature fluctuations. Although these inconsistencies may be attributed to systematic effects, there remains the possibility that they indicate new physics and various theories have been proposed to explain them. One possibility, which we discuss in this review, is the generation of perturbation modes during the early pre-inflationary epoch, when the Universe may not obey the cosmological principle. Better measurements will provide better constraints on these theories. In particular, we propose measurement of the dipole in number counts, sky brightness, polarized flux and polarization orientations of radio sources. We also suggest test of alignment of linear polarizations of sources as a function of their relative separation. Finally we propose measurement of hemispherical anisotropy or equivalently dipole modulation in radio sources.  相似文献   

Short-term predictions by statistical methods in regions of varying dynamical error growth in a chaotic system     

A. K. Mittal  U. P. Singh  A. Tiwari  S. Dwivedi  M. K. Joshi  K. C. Tripathi 《Meteorology and Atmospheric Physics》2015,127(4):457-465

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Bianchi type-I cosmological models with perfect fluid in general relativity     

Rishi Kumar Tiwari 《中国天文和天体物理学报》2010,10(4)

Einstein's field equations with variable gravitational and cosmological constants are considered in the presence of perfect fluid for the Bianchi type-Ⅰ universe by assuming that the cosmological term is proportional to R-m(R is a scale factor and m is a constant).A variety of solutions are presented.The physical significance of the respective cosmological models are also discussed.  相似文献