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S. K. G. Krishnamacharyulu Bh. V. V. Gopalarao I. V. Radhakrishna Murthy 《Pure and Applied Geophysics》1990,132(4):719-731
Magnetic anomaly profiles over two thin sheets separated by a small distance resemble those of dykes andvice versa. Interpretation of anomalies over a pair of sheets based on the magnetic properties of dykes predicts a dyke whose centre lies midway between the positions of the sheets. The dyke, on the other hand, is magnetically equivalent to a pair of sheets, both lying at the same depth and having the same magnetization.The magnetic anomalies due to a pair of sheets can be interpreted by framing linear equations between the anomalies and their distances measured from an arbitrary reference. Application of this method to anomalies of dipping sheets with a finite depth extent is indicated. 相似文献
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Summary The inter-dependences between local dust, thermal stability of the air and precipitation have been examined from the available data of two selected pairs of years for the station, Delhi, in northwest India. The indications are that the dust enters into the precipitation picture by virtue of its role in radiation balance during the relatively dry period, January to June, and by virtue of its role in cloud microstructure during the wet period, July to September. 相似文献
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A Mary Selvam A S Ramachandra Murty R Vijayakumar S K Paul G K Manohar R S Reddy B K Mukherjee Bh. V. Ramana Murty 《Journal of Earth System Science》1980,89(2):215-230
The thermodynamical and microphysical characteristics of monsoon clouds in the Poona, Bombay and Rihand regions were investigated using extensive aircraft in-cloud observations. The number of clouds sampled at Poona, Bombay and Rihand is 2199, 169 and 104 respectively. The temperatures inside the cloud are colder than its environment at Poona and Rihand. The maximum difference is about 3°C at the cloud base level and the difference decreased with height. At Bombay the difference is less than 1°C and at some levels the temperatures inside the cloud are warmer than its environment. The lapse rates of temperatures inside the cloud are slightly less than those in the immediate environment of the cloud. The environmental lapse rates are nearly equal to the saturated adiabatic value. The positive increments in liquid water content (LWC) are associated with the increments in temperature inside the cloud. Similarly positive increments in temperatures inside the cloud are associated with the increments in temperature of its immediate environment at the same level or the layer immediately above. The maximum cloud lengths observed at Poona and Bombay respectively are 14 and 3 km. The horizontal cross-section of LWC showed a maximum number of 13 peaks in clouds at Poona while only 7 peaks were observed at Bombay. The location of maximum LWC in the horizontal cross-section is more or less at the centre of the cloud. The LWC profile showed an increase with height from the base of the cloud at Poona and Bombay. There is no marked variation of LWC with height at Rihand. The total droplet concentration at different altitudes at Poona and Bombay is in the range 28–82 cm?3. The size distribution of cloud droplets experienced a broadening effect with increase in height from the cloud base at Poona. The broadening effect at Bombay is not as marked as that at Poona. 相似文献
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Mohamad?Asrul?MustafarEmail authorView author&#;s OrcID profile Wim?J.?F.?Simons Felix?Tongkul Chalermchon?Satirapod Kamaludin?Mohd?Omar Pieter?N.?A.?M.?Visser 《Journal of Geodesy》2017,91(10):1241-1259
The existence of intra-plate deformation of the Sundaland platelet along its eastern edge in North Borneo, South-East Asia, makes it an interesting area that still is relatively understudied. In addition, the motion of the coastal area of North-West Borneo is directed toward a frontal fold-and-thrust belt and has been fueling a long debate on the possible geophysical sources behind it. At present this fold-and-thrust belt is not generating significant seismic activity and may also not be entirely active due to a decreasing shelfal extension from south to north. Two sets of Global Positioning System (GPS) data have been used in this study; the first covering a time period from 1999 until 2004 (ending just before the Giant Sumatra–Andaman earthquake) to determine the continuous Sundaland tectonic plate motion, and the second from 2009 until 2011 to investigate the current deformations of North Borneo. Both absolute and relative positioning methods were carried out to investigate horizontal and vertical displacements. Analysis of the GPS results indicates a clear trend of extension along coastal regions of Sarawak and Brunei in North Borneo. On the contrary strain rate tensors in Sabah reveal that only insignificant and inconsistent extension and compression occurs throughout North-West Borneo. Moreover, station velocities and rotation rate tensors on the northern part of North Borneo suggest a clockwise (micro-block) rotation. The first analysis of vertical displacements recorded by GPS in North-West Borneo points to low subsidence rates along the western coastal regions of Sabah and inconsistent trends between the Crocker and Trusmadi mountain ranges. These results have not been able to either confirm or reject the hypothesis that gravity sliding is the main driving force behind the local motions in North Borneo. The ongoing Sundaland–Philippine Sea plate convergence may also still play an active role in the present-day deformation (crustal shortening) in North Borneo and the possible clockwise rotation of the northern part of North Borneo as a micro-block. However, more observations need to be collected to determine if the northern part of North Borneo indeed is (slowly) moving independently. 相似文献
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The rocketsonde data obtained from the launchings made at Thumba (8°3215N, 76°5148E) during the winter period 1970–71, as already reported, have indicated that warmings of noticeable magnitude occurred at high levels (upper stratosphere and mesosphere) over this tropical station during the period mentioned. The mean monthly radiosonde temperatures of 50, 100 and 300 mb levels at Thumba (Trivandrum) and Delhi (28°35N, 77°12E) during the same period have also pointed out certain anomalies consistent with the warmings referred to above at Thumba. The radiosonde temperatures of the two stations, Thumba (Trivandrum) and Delhi, have now been examined, along with the values of total ozone, for the ten winter periods commencing from 1961–1962. The analysis has pointed out the possibility of high-level warmings also having occurred in the past over the Indian region during the winters of 1963–1964 and 1967–1968, which are also the periods when prominent warmings are definitely known to have occurred at higher latitudes. The behaviour of total ozone has been found to be different in the different years of the warmings. The features noticed have been presented and discussed. 相似文献
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H N Bhalme R S Reddy D A Mooley Bh V Ramana Murty 《Journal of Earth System Science》1981,90(3):245-262
The literature on influences of solar activity on the Indian weather and climate is reviewed since the discovery of sunspot cycle. Fluctuations in solar activity are undoubtedly a factor affecting weather and climate. Although the results of some of the studies are conflicting, Indian weather and climate is, in general, inversely related to sunspots. However, the areal extent of floods in India seems to expand and contract in phase with the Hale double sunspot cycle, suggesting that the flood rhythm is in some manner controlled by long-term solar activity related to solar magnetic effects. All the evidences of solar influences on weather and climate may have practical implications in improving long-range forecasting of weather and climate, once the physical coupling mechanisms and their modification by other factors are clearly understood. Some of the promising plausible physical mechanisms for explaining solar effects on weather and climate are also discussed. 相似文献
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A Mary Selvam A S Ramachandra Murty Bh. V Ramana Murty 《Journal of Earth System Science》1978,87(11):179-191
Two numerical cloud seeding experiments, using historic rainfall for the Deccan plateau region in Maharashtra state, were performed adopting different simulation techniques. The data used consisted of 1-day total rainfall for the 5-year period 1951–55. A double-area cross-over design with area randomisation was adopted. The first experiment, EXP-TR, was based on the simulation technique of Twomey and Robertson which involves about 100 hr of Robotron EC-1040 computer time. The second experiment, EXP-MMM was based on a different simulation technique proposed in the present study. The results of EXP-TR and EXP-MMM have shown close agreement. The numerical simulation technique of EXP-MMM is more promising for the following two reasons: (i) the computational time is reduced by about an order of magnitude without compromising the scientific value of the results, and (ii) a direct estimate of the lower limit of the double ratio value which can be detected at 5% level of significance is defined. The results of the two numerical experiments suggested that, for the Deccan plateau region, 15 and 20% increases in rainfall due to seeding could be detected with 80% or more probability in 5 years. 相似文献