Estimating surface sensible heat flux using sodar and surface temperature measurements in the evolving convective boundary layer     

K.Sen Gupta  P.K. Kunhikrishnan  V. Radhika  K.Narayanan Nair 《Atmospheric Research》1986,20(2-4)

A simple method is described for estimating the sensible heat flux by using a Doppler sodar system and a thermal probe. This method, which can be applied to a convective boundary layer in morning hours, is based on knowing the zero heat flux level from the reflectivity and the vertical wind speed.  相似文献   

The old alluvium of Singapore and the extinct drainage system to the South China Sea     

Avijit Gupta  Ausafur Rahman  Wong Poh Poh  John Pitts 《地球表面变化过程与地形》1987,12(3):259-275

In both sand quarry faces and boreholes the Old Alluvium of Singapore is a matrix supported pebbly sand with minor beds of better sorted sands and clays. The beds can be grouped into four textural classes (pebbles, coarse sand with fine pebbles, medium to coarse sand, clay, and silt), each with characteristic sedimentary structures. The deposit appears to be the proximal facies of an ancient braided river alluvium of possible Pleistocene age. This widespread but scattered alluvium is found both on land and offshore on the Sunda Shelf in Southeast Asia. It is believed to have been deposited during low sea levels. In Singapore, the mineralogy of the grains forming the Old Alluvium suggests a mixed provenance of granitic and low-grade metamorphic origin. The volume and freshness of the deposited material indicate an environment of considerable relief, seasonal rainfall, and extremely active erosional processes, conditions considerably different from the current ones. The Old Alluvium was probably deposited by seasonal rivers which experienced periodic large floods. Such regional conditions could have prevailed over much of Southeast Asia at the time of deposition of the Old Alluvium.  相似文献   

Interface Upconing Due to a Horizontal Well in Unconfined Aquifer   总被引：2，自引：0，他引：2  

A. Das Gupta  Vilas P. Gaikwad 《Ground water》1987,25(4):466-474

  相似文献   

Relationship of gravity anomalies and tectonics in Assam, India     

R.K. Verma  R.P. Gupta 《Tectonophysics》1973,18(1-2)

Gravity data from Assam compiled on Bouguer, Hayford and Airy isostatic anomaly maps have been interpreted in terms of tectonics of the area. The gravity anomalies suggest that the Dauki fault is very deep-seated. A gravity high of about 60 mGal near Haflong is interpreted as being the expression of an intrusive body with a density contrast of about + 0.15 g/cm₃ with respect to the surroundings. From isostatic considerations, approximate crustal thicknesses over the Shillong Plateau, the Upper Assam valley and the Surma valley are estimated to be 40, 29 and 22 km respectively, suggesting a sharp change in crustal thickness from the Shillong Plateau to the Surma valley across the Dauki fault.  相似文献   

Fluoride in the Baltic     

B. Kullenberg  R. Sen Gupta 《Geochimica et cosmochimica acta》1973,37(5):1327-1337

A study of the fluoride concentration in several marine areas around Sweden is reported. It has been established that the fluoride-chlorinity relationship at low chlorinities is much affected by river runoff due to removal of fluoride by the agency of settling particles. The effect of this is enhanced where rivers open into relatively high-saline water. In the Baltic, which is strongly influenced by river runoff, the fluorido to chlorinity ratio is much higher than in the open oceans. In the oxygenated layers of the Baltic fluoride shows little variation with time, but in the anoxic layers the fluoride concentration decreases with time. In the deeper layers of the Kattegatt an increase in fluoride could be noted which might be due to dissolution of minerals. An overall relationship between fluoride concentration and chlorinity in offshore waters has been established.  相似文献   

On disturbances in a viscoelastic rod (of variable cross-section) of Reiss type placed in a magnetic field     

C. R. Sen Gupta 《Pure and Applied Geophysics》1972,97(1):32-36

Summary The equations of mechanical motion and electromagnetic equations of Maxwell have been used to investigate the disturbances in a viscoelastic rod of Reiss type placed in a magnetic field.  相似文献   

Electromagnetic response of a covered inhomogeneous permeable conductor in time domain     

Chandra P. Gupta  Upendra Raval 《Pure and Applied Geophysics》1971,92(1):169-184

Summary An initial value induction problem has been solved to examine the response of a massive sulphide ore body under conditions of common occurence. The generalized expression for the induced field due to a step-function dipolar field in the presence of a non-uniformly conducting permeable sphere surrounded by a finitely resistive overburden has been derived. Two cases, when the concentric shell is (i) insulated from and (ii) in galvanic contact with the inner core, have been considered. The analytical results are in computable form to yield the decay-characteristics for application in geoelectromagnetics. Particular cases of the problem treated by the other investigators are discussed.N.G.R.I. Contribution No. 71-234  相似文献   

Terrestrial heat flow in various parts of India     

R. K. Verma  R. U. M. Rao  M. L. Gupta  G. Venkateshwar Rao  V. M. Hamza 《Bulletin of Volcanology》1969,33(1):69-88

Results of heat flow studies made in different parts of India including Kolar Gold Field, Cuddapah basin, Singhbhum thrust zone, Aravalli mountain system of Precambrian age, Godavary valley of Mesozoic age and Cambay basin of Cenozoic age are discussed. Heat flow has been found to be low in the southern part of the Preambrian shield. Relatively higher values have been obtained along the northeastern (Singhbhum) and the northwestern parts of the shield (Aravallies). High heat flow has been found along the southeastern part of the Godavary valley and the Cambay basin. The correlation of heat flow with geology and tectonic history in the respective areas is discussed.  相似文献   

A Study on the Effect of Temperature upon the Toxicity of Sodium Pentachlorophenate to the Freshwater Snail Viviparus bengalensis L.     

P. K. Gupta  V. S. Durve 《洁净——土壤、空气、水》1984,12(4):369-375

The toxicity of Na-pentachlorophenate to Viviparus bengalensis is investigated by batch tests with daily exchange of medium in the temperature range between 19 °C (February), 27 °C (April), 32 °C (June) and 30 °C (August) at times of exposure between 12 and 96 h. In the range of higher concentrations, pronounced abnormalities in behaviour by secreting mucus and discharging eggs and embryos occur. The LC₅₀ are lowest for all times of exposure at 27 °C, whereas the times of survival with a given concentration are highest at 30 °C. From the LC_{50, 96h, 27°C} = 66 μg/l results a safe concentration of only 47 μg/l Na-pentachlorophenate for Viviparus bengalensis.  相似文献   

Origin and evolution of a migmatite   总被引：5，自引：0，他引：5  

W. Johannes  L. N. Gupta 《Contributions to Mineralogy and Petrology》1982,79(2):114-123

The development of a stromatic migmatite exposed east and southeast of Arvika (Western Sweden) is described in four stages beginning with the country rock and following evolution through three areas characterized by low, medium and high amounts of leucosomes (areas L, M, and H, respectively).The country rock is a paragneiss composed of thin, alternating fine- and coarse-grained layers. Composition of the layers varies from granitic (fine) to tonalitic (coarse layers).The bulk of the stromatic migmatite is composed of leucocratic layers of magmatic appearance (leucosomes) and darker layers of gneissic aspect (mesosomes). Petrographical and chemical data (given in the form of Niggli values and K₂O/SiO₂ diagrams) show a close relationship between the fine-grained paragneiss layers and the leucosomes on the one hand and between the coarse-grained layers and the mesosomes on the other.At relatively low temperatures only those gneiss layers with a suitable (granitic) composition are transformed into leucosomes. This process is interpreted to be due to recrystallization of the felsic minerals via partial melting and to the separation of biotite.With increasing metamorphism, leucosomes become broader and more frequent due to partial melting of layers with less suitable composition. Contacts between different generations of leucosome can be recognized in the form of relict melanosomes.These observations favour essentially isochemical melting, followed by later in-situ crystallization. This model of an isochemical layer-by-layer transformation is supported by the preferential formation of hornblende in leucosomes and relict melanosomes, as well as by almost identical compositions of migmatite and country-rock plagioclase.  相似文献