Estimation of surface latent heat fluxes from IRS-P4/MSMR satellite data

The brightness temperatures of the Microwave sensor MSMR (Multichannel Scanning Microwave Radiometer) launched in May 1999 onboard Indian Oceansat-1 IRS-P4 are used to develop a direct retrieval method for latent heat flux by multivariate regression technique. The MSMR measures the microwave radiances at 8 channels at frequencies of 6.6, 10.7, 18 and 21 GHz at both vertical and horizontal polarizations. It is found that the surface LHF (Latent Heat Flux) is sensitive to all the channels. The coefficients were derived using the National Centre for Environmental Prediction (NCEP) reanalysis data of three months: July, September, November of 1999. The NCEP daily analyzed latent heat fluxes and brightness temperatures observed by MSMR were used to derive the coefficients. Validity of the derived coefficients was checked within situ observations over the Indian Ocean and with NCEP analyzed LHF for global points. The LHF derived directly from the MSMR brightness temperature (Tb) yielded an accuracy of 35 watt/m². LHF was also computed by applying bulk formula using the geophysical parameters extracted from MSMR. In this case the errors were higher apparently due to the errors involved in derivation of the geophysical parameters.     

Some features of the arid area variations over India: 1871–1984

Spatial variability of the annual rainfall over drier regions of India is studied by examining the variations in the arid areas. A long period (1871–1984) arid area series has been prepared for the entire country, including the two broad subregions of North India and Peninsular India, using annual rainfall data from 306 well distributed stations. Following an objectively determined criterion based on rainfall amount alone, the yearly area under arid conditions is obtained by totalling areas which received annual rainfall totals less than 560 mm. The interannual variability of the arid area series is large and its distribution is highly right-skewed, demonstrating large spatial variations in the annual rainfall over India. Statistical tests do not suggest any significant long-term trend in the arid area series, but persistently low values of the arid area after 1941 are noteworthy. Implications for the study of risk analysis and assessment of drought and desertification processes are discussed.     

Cuttability assessment of hard coal seams

Summary A number of field and laboratory tests have been carried out on more than 15 coal seams of compressive strengths ranging from 19 MPa to 44 MPa to evolve methods which would help in the selection of suitable coaling machines for hard coal seams. The effect of physico-mechanical properties on cuttability were studied in the laboratory for all these coal seams to identify the relevant parameters affecting the specific energy of coal cuttability. These data were subjected to regression analysis to find the best fit for estimation of laboratory specific energy of coal samples on the basis of simple laboratory and field tests for the strength parameters. Field studies were also conducted over a large number of active mechanized coal faces to study in situ cuttability along with the geo-mining conditions of the site. The field and the laboratory data so generated were correlated and an attempt is made to establish a relationship for estimating the field specific energy for a particular capacity of coaling machines by considering the geo-mining domain of the field in totality.     

Generalized thermoelastic longitudinal waves in unbounded medium

Summary In this paper the generalized thermoelastic longitudinal waves and the temperature field set up due to coupling of the displacement and the temperature fields, with heat wave travelling with certain finite velocity, in an unbounded medium are studied. The thermoelastic displacement potential and the temperature field at any point are obtained in terms of the surface integrals involving the potential, the temperature and their normal derivatives.Notation x _i the cartesian coordinate system,i=1,2,3 - n (u _i) the displacement vector - (/x _i) the del operator - _t /t the derivative with respect to time - T _o the temperature corresponding to the natural stat of zero stress and strain - T Absolute temperature - c _e the specific heat - , Lamé's constants - ₀ the density - coefficient of linear thermal expansion - K thermal conductivity coefficient - _kk u - ₀ the relaxation time     

Resistivity profiles over quartz reefs of Dhanbad

Summary A number of resistivity profiles over quartz reefs have been taken using Wenner and Schlumberger configurations around Dhanbad in order tofind the potential of these for water accumulation. These reefs give rise to both resistivity highs and lows as compared to the background. The results are discussed in the light of known theories. Some suitable sites for water accumulation have been delineated.     

Least square criterion for isostasy

Summary Least square criterion has been introduced to specify the order of isostatic compensation of mountains. The hydrostatic stability of the mountains is of basic significance in plate tectonics. However different concepts of isostasy differ in the evaluation of its order. An elegant and rapid technique is developed which extends the symmetric matrix method of root estimation byNegi andGarde [1]³) to provide a stability test through the mathematical expectation of the root increment. Application is illustrated for Rocky Mountains, United States.     

Mechanical response of a piezoelectric composite transducer subjected to a thermal field

Summary The present paper studies the mechanical response of a piezoelectric composite transducer—with an elastic compliance partly constant and partly variable with time—acted upon by suitable thermal field besides the electrical voltage. The Laplace transform has been applied to solve the problem.     

A study of the vertical magnetic anomaly caused by magnetite deposits in Sua area of Palamau district,Bihar (India)

Summary A magnetic survey carried out in Sua area of the Palamau district, Bihar (India) has shown very interesting anomalies. The survey has been conducted specially to obtain the extension of the magnetite deposits which are being quarried at Sua. The interpretation of magnetic anomalies have clearly brought out the following facts: a) the magnetite is extending both sides of the quarry to a considerable distance, b) the nature of the anomaly indicates that the magnetite occurs in the form of veins. It has also been possible to find out the thickness of the veins and the depth at which they occur.     

Some studies in thermal demagnetization of basic rocks from the Mull area of northern England

Summary Thermal demagnetization of large number of samples form the Isle of Mull have been carried out. The rocks belong to the Tertiary age. The results indicate that the rocks have been magnetized in the prevalling geomagnetic field at the time of formation. Some of the rocks indicate movement during cooling.