011740   Balakrishnan Nair T M;Ramaswamy V;Parthiban G;Shankar R (NO, National Institute of Oceanography, Dona Paula, Goa-403 004) : Factors controlling vertical fluxes of particles in the Arabian Sea. J Geol Soc India 1999, 54(4), 369-78.

Particle fluxes were measured using six time-series sediment traps at three sites in the western (16°20'N;60°30'E), central (14°31'N;64°46'E) and eastern (15°31'N;68°43'E) Arabian Sea. Trap deployment depths were between 900 and 3000 m and collection period was from December 1992 to February 1994. Annual particle fluxes showed an east-west trend with minimum fluxes (22.25 g m^-2) in the eastern Arabian Sea and maximum fluxes (69.81 g m^-2) in the western Arabian Sea. Carbonates, contributed mainly by foraminifers and coccolithophorid, are the dominant component in all the traps. Opal fluxes were maximum in the western Arabian Sea. At all the locations, lithogenic percentages increased with depth whereas organic carbon percentages decreased. Particle flux patterns show a strong seasonality with peak fluxes during the southwest (SW) monsoon (June to September). Relatively high fluxes were also observed during the northeast (NE) monsoon (December to February). In the western Arabian Sea, particle fluxes are dominated mainly by carbonates during the early SW monsoon but by biogenic silica during the late SW monsoon. The increase in particle fluxes during the early SW monsoon is related to variations in the mixed layer depth which, in turn, is controlled by the strength of the Findlater Jet and the curl of the wind stress.

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011739   Agrawal S (Department of Geology, University of Rajasthan, Jaipur-302 004) : Geochemical discrimination diagrams : a simple way of replacing eye-fitted field boundaries with probability based classifier surfaces. J Geol Soc India 1999, 54(4), 335-46.

Subjective, eye-fitted, field boundaries in geochemical discrimination diagrams constitute one of the possible reasons for their often-noted inability to determine the source regime/tectonic environments of igneous rocks. A simple method is described to replace the eye-fitted field boundaries between the groups with the probability based classifier surfaces. It involves projection of the assignment rules obtained from linear discriminant analysis onto the binary or ternary discrimination diagram of raw variables. The method is illustrated by obtaining classifier surface between I- and S- type granites in Na2O-K2O space and between Anorthosite/Rapakivi (AR) and Ring Complex (RC) granites in Na2O-MgO space. The need for explicity ensuring adequacy of samples, selection of suitable variables, evaluation of rate of misclassification and a better understanding of the unique influence of tectonic environments on magmatic process is emphasized for optimizing the performance of the classifier surface.

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010777   Srivastava K;Singh R N (NO, National Geophysical Research Institute, Uppal Road, Hyderabad-500 007) : Influence of random thermal conductivity on the subsurface temperature fluctuations. J Geophys 1999, 20(2), 89-92.

Subsurface rocks show complex variability in the thermal parameters and sources. As the knowledge of the subsurface thermal fields is being increasingly used in understanding global processes, it is necessary to study the heat, conduction problem in a stochastic framework. The stochastic heat conduction equation has been solved by a new perturbation method incorporating randomness in the thermal conductivity to estimate analytically the first two statistical moments i.e. mean and variance of the temperature field. The randomness in the thermal conductivity is expressed by a mean part plus a fluctuation part where the fluctuation part is represented by a known correlation function. The information on the correlation structure for most geological situations is easily available. The anlytical expression obtained for the variance in temperature reveals that it is a function of the coefficient of variability of the thermal conductivity and the correlation length scale. The methodology developedd has been applied to a sedimentary basin example. Results obtained bring out the thermal state with its associated error bounds. The error bounds is seen to broaden with depth and increases with an increase in the coefficient of variability in the thermal conductivity.

010776   Srinivas S;Murthy A S K;Yadav G S;Srivastava K M (NO, National Geophysical Research Institute, Uppal Road, Hyderabad-500 007) : Geophysical responses of Chattisgarh region, Madhya Pradesh, India. J Geophys 1999, 20(2), 71-8.

Under the deep continental studies project, gravity and magnetic surveys were undertaken along a transect of 382 km. length in near east-west direction across the Chattisgarh region, Madhya Pradesh, India. An attempt is made to address the gravity and magnetic signatures in terms of lithological and structural features for the first time, which were so far remained uninvestigated in good detail. The gravity and magnetic responses of the region are quite revealing. The gravity profile profile defined the Chattisgarh basin configuration and demarcated the Sakoli metasedimentary belt and Sonakhan greenstone belt on eitherside of the Chattisgarh basin. The Chattisgarh basin recorded a broad magnetic high compared to Sakoli belt and Sonakhan greestone belt, which were reflected as lows on eitherside of the basin. Besides this, the magnetic anomalies broughtout the presence of possible basic intrusives into the sediments basement.

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010775   Satyanarayana K;Rao G N;Bhagwan M S K;Prasad P V S (NO, ONGC, Kanjurmarg, Mumbai) : Integrated facies analysis to identify depositional environments in eocene sequence in Krishna-Godavari Basin. J Geophys 1999, 20(2), 55-63.

Hydrocarbon exploration in Krishna-Godavari Basin was started with deep drilling in 1978 and so far more than 250 wells were drilled over 125 structures. Though initial success was registered in Upper Cretaceous sequence, now the basin has proved hydrocarbon potential in all geological sequences from Pliocene to Permain. However, the Eocene section towards wouth-eastern coastal tracts of the basin is found to be more prolific. The lower Tertiary section in this part of the basin is identified as seprate petroleum system with Paleocene argillaceous source, Lower Eocene sandy reservoirs and middle Eocene carbonate cap facies. An attempt has been made to integrate the available information including cores, electrologs and seismic data to bring out a depositional model for most promising Lower Eocene sand bodies which are identified near-shore bars and/or channel fill deposits.

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010774   Pandey R N;Agnihotri A K;Ghosh D (Division of Soil Science and Agricultural Chemistry, Indian Agricultural Research Institute, New Delhi-110 012) : Clay mineralogy of soils of Gagas sub-catchment of Ramganga catchment in U.P. hills. Clay Res 1999, 18(1), 40-6.

Mineralogical composition of A and B horizons of eight identified soil series of Gagas sub-catchment of Ramganga catchment in U.P. hills were investigated using X-ray diffraction technique and chemical analysis of the soil clays. The X-ray diffraction patterns showed the presence of mica, Fe-chlorite, mica-chlorite interstratified minerals, feldspar and quartz. The mineralogical analysis indicated that mica (36 to 41%) and chlorites (28 to 35%) were the major clay minerals associated with vermiculites (6 to 12%), smectites (5 to 8%) and kaolinites (4 to 5%). The weathering mean of these soils ranged from 6.3 to 6.5 to qualify them as young soils.

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010773   Padhi R N;Ramakrishna T S (NO, Geological Survey of India, 1250 B, Road No. 62, Jubliee Hills, Hyderabad-500 033) : Tectonic history deduced from a combined study of Bouguer gravity and lineaments of Gondwana basins in Maharashtra. J Geophys 1999, 20(2), 79-82.

Lineaments as identified from the Landszat (MSS) imagery of the Gondwana basins and adjoining terrain in Maharashtra are analyzed together with the Bouguer gravity map of the area so as to obtain a more conclusive information in respect of deep-seated features and relalated tectonic history of the area. It is observed that basin boundaries of the Gondwana coincide with gravity lineaments while the imagery lineaments show lateral shift away from these boundaries. The deposition of Gondwana rocks, as studied from geology, geomorphology, geophysics and tectonics of the area, appears to be controlled by two major NW-SE trending crustal faults passing through Hinganghat and Kharsingi in the south and central parts; a two stage crustal subsidence in the northern part in the Katol basin; fan shaped palaeo depressions around Nagpur and a few subbasinal faults.

010772   Mallick K;Sharma K K (NO, National Geophysical Research Institute, Hyderabad-500 007) : Inter-relationship of Bouguer regional and residual gravity anomalies - a case study from earthquake - prone Latur region, Maharastra, India. J Geophys 1999, 20(2), 65-9.

Bouguer gravity anomaly is often partitioned into regional and residual components in order to model geological structures. However, since the regional-residual resolution by most of the existing methods is seldom exact, there is a certain amount of uncertainly in the interpretation. A new regional - residual separation scheme, based on finite element approximation and briefly outlined, does reduce such uncertainties. Bouguer gravity anomaly in earthquake-prone Latur area, Maharastra was chosen to compute the regional and residual components by this new scheme and establish their inter-relationships. Ideally the regional and residual anomalies should be uncorrelated. Computations show that the correlation coefficients between Bouguer and regional, and Bouguer and residual are 0.789 and 0.529 respectively. The regional and the residual anomalies, on the other hand, show a small inverse correlation (correlation coefficient = -0.105), thereby proving that the regional and residual anomalies are nearly uncorrelated. A change in gradient in regional gravity anomaly starting eastward from the epicentral region near Killari appears tectonically significant. The NW - SE striking residual low in the central part seems to correspond to a fracture zone.

010771   Laskar S K (Department of Mathematical Sciences, Tezpur University, Tezpur-784 001) : Computation of gradients of two-dimensional potential fields from boundary data: theory and practice. J Geophys 1999, 20(2), 83-7.

Gradients of a potential field are computed on reproduction of the field from boundary data by simple and double layer boundary densities. It is shown theoretically that the gradients computed at the boundary are highly sensitive to error in input data, the normal derivative appearing with more error than the tangential derivative. The error in them considerably reduces when computed at a level above the boundary. It is shown that the horizontal gradient computed at a higher level is stable and more reliable than the vertical gradient computed at the same level.

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010770   Gupta V;Poulos H G;Reid S G (NO, The University of Sydney, NSW 2006, Australia) : Engineering geology of Delhi : an overview. Indian Geotech J 1999, 29(3), 262-74.

Geotechnical properties, including dynamic characteristics of soil layers in a profile, are being deduced from the collected boring and testing results and various available correlation curves. The earthquake spectra obtained at the surface from analysis are being used in the preparation of seismic design interaction curves for different configured structures popular in Delhi.

010769   Dubey S C;Mishra A P (Department of Physics, Government Girls' College, Sidhi-486 661) : CMEs associated intense geomagnetic storms observed during solar maximum 1989-1991. Indian J Phys-Pt B 1999, 73(5), 701-9.

Analyzed the set of 50 intense geomagnetic storms associated with Dst decrease of more than 100 nT, observed during solar maximum period (1989-1991) of solar cycle 22. Compile these selected intense geomagnetic storm events and find out their association with coronal mass ejections (CMSs). Authors have found that 80% intese geomagnetic storms associated with coronal mass ejections. Two geomagnetic storm events observed during 25/04/89-01/05/89 and 08/07/91-12/07/91, described in detail. Concluded that different phases of geomagnetic storms are closely correlated with interplanetary parameters. Two kinds of geomagnetic storms known as sudden commencement storm and gradual commencement storm and different storm time changing phenomena have been discussed.

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010768   Bindu S (Department of Physics, University of Kerala, Kariavattom, Trivandrum-695 581) : Dynamics of the geomagnetotail plasma sheet during storm time and non-storm time substorms. Indian J Phys-Pt B 1999, 73(5), 717-23.

Selected 40 substorm events from AMPTE/IRM satellite observations in the geomagnetotail at distances between 10 and 19 RE (1RE = 6371 km) and separatedd storm time and non-storm time substorms and studied the dynamics of the near-earth geomagnetotail plasma sheet for the two types. It was found that most of the signatures of the plasma sheet, typical for substorms, are strongly influenced by magnetic storm activity. The field line curvature radius and chaos parameter in the plasma sheet are much more pronounced for substorms which occur during the main phase of magnetic storms than for non-storm substorms. Moreover, only for storm time substorms, the specific entropy in the plasma sheet decreases during the expansion phase.

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010767   Arumugam M;Sagayadoss A;Prabhakaran R (Department of Geology, Annamalai University, Annamalainagar-608 002) : Geochemistry and mineralogy of Panruti clays, Cuddalore district, Tamil Nadu. Clay Res 1999, 18(1), 32-9.

Commercial grade kaolinite clays are found associated with Tertiary formations near Panruti. Samples were collected representing five profiles of clay horizons for mineralogical and chemical studies. Focus on the geochemistry and clay mineralogy of the study area. The samples contain <60>2 μm size of clays ranging from 55 per cent to 60 per cent. The alumina is high with low alkalies and iron. The XRD patterns of the representative samples show well crystalline kaolinite as the major component. The quartz is the non-clay mineral present. These clays are recommended for lower ceramic products.

009727   Yogesh Kant;Badarinath K V S (National Remote Sensing Agency, , Balanagar, Hyderabad-500 037) : Determination of effective emissivity and temperature over inhomogeneous land surfaces - results from field campaign. Curr Sci 1999, 77(10), 1348-51.

Describes the use of satellite received radiance for estimation of surface emissivity in the sensor's spectral channels over heterogeneous areas. The estimation of emissivity is based on the information of Normalized difference Vegetation Index in conjunction with proportion of vegetation cover at pixel resolution. The estimated emissivity values at channel resolution have been used in the split-window algorithm for estimation of surface temperature over heterogeneous surfaces from satellite sensor data. The estimated surface temperature values are compared with the in situ data over the region and are found to be within error limits of less than 1°. The results indicate the effective use of the methodology for land surface estimation over heterogeneous landscape.

009726   Vashistha R D;Madan R;Srivastav S K (Indian Meteorological Department, , Pune-411 005) : Spectral (direct) solar irradiance at Pune. Mausam 1999, 49(4), 487-92.

Direct Solar Irradiation (DSI) measurements are made with pyrheliometers. When used with selected filters, the spectral distribution can be worked out. Measurements at Pune indicate that large scale attenuation takes place in blue-green regions of solar spectrum likely due to aerosol particles injected by industrial advancement over the region, consequent rapid urbanisation and resultant change land-use patterns. Values show evidences on the role played by moisture field on the transmission characteristics of the Pune skies. The afternoon irradiances are seen to be generally higher than the forenoon values. However, IR and yellow-orange wavelengths have higher irradiances in the forenoons during the premonsoon months and occasionally even in March. Over a year 774 Wm^-2 of irradiance can be expected on any cloudless occasion around noon time, the individual spectral values vary depending on the actual sky and atmospheric conditions. From the comparative study of the irradiances in the different spectral regions, inferences could be drawn on the changes that take place in the size distribution of aerosol particles during a day.

009725   Thapliyal V;Rajeevan M;Patil S R (NO, Meteorological Office, Pune-411 005) : Relationship between Indian summer monsoon rainfall and sea surface temperature anomalies over equatorial central and eastern Pacific. Mausam 1998, 49(2), 229-34.

Sea surface temperature (SST) variations over the three key regions over equatorial Pacific, viz., Nino (1+2), Nino 3 and Nino 4 and their relationships with Indian summer monsoon rainfall have been examined. On monthly scale, SST anomalies over the three key regions show an oscillatory type of lagged correlations with Indian monsoon rainfall, positive correlations almost one year before the monsoon season (CC's are of the order of 0.3) which gradually change to significant negative correlation peaking in September/October during/after the monsoon season. The variations on seasonal scale also exhibit the same pattern of monthly variations but more smooth in nature. Composites of similar monsoon years show that during deficient (excess) monsoon years SST anomalies over all the three regions have warmer (cooler) trend which starts about 6 months prior to monsoon season. Tendencies of SST anomalies from previous winter (DJF) to summer (MAM) seasons over Nino 3 and Nino 4 regions are better predictors than El-Nino categories currently being used in IMD's operational LRF model. By using tendency of SST over EL-Nino-4 region, in place of the category of El-Nino, the 16 parameter operational Power Regression Model of IMD has been modified. The new forecast model shows better reduction in the forecast error.

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009724   Tejwani K G (NO, CSWCRTI, Dehradun-248 195) : Watershed management in Asia, Africa and the Pacific. Indian J Soil Conserv 1999, 27(2), 145-51.

Managing Land, Water and Vegetation, as natural resources, on sustainable basis is historically a matter of tradition with human beings. They have realized early in the civilization that land-water-vegetation constitute their life and survival. One can cite many unique systems of managing land-water-vegetation in Asia, Africa and Pacifics. Yet several of them may have brokendown. China, India, Indonesia, Malaysia, Nepal, Pakistan, Philippines and Thailand are supposed to have excellent to good status of watershed management; others have fair to less than satisfactory. Strong operational linkages between Researchers and Trainers; and Government and Non-Government agencies are needed, for success of watershed for protection, production and development in this part of the world.

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009723   Suresh R (NO, Regional Meteorological Centre, Madras) : On some aspects of boundary layer over Madras airport. Mausam 1999, 49(4), 528-30.

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009722   Suresh R (NO, Regional Meteorological Centre, Chennai) : Determination of fractal dimension of chaotic attractor for maximum temperature over Madras. Mausam 1998, 49(2), 167-72.

Dimensions of attractions of daily maximum temperature (during March-May) recorded by the two observatories of Madras, viz, Nungambakkam and Meenambakkam are estimated from phase space trajectories by the method of deterministic chaos. The dimensions provide the basic information on the minimum number of parameters required to understand the complex dynamical system and also the upperbound (degrees of freedom) of such parameters that are sufficient to model the system. The fractal dimension for the weather event, viz, maximum temperature over Madras is between 3.5 and 3.9 suggesting 4 parameters are necessary to model the system and a maximum of 19 parameters are sufficient.

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009721   Sundar D;Shankar D;Shetye S R (NO, National Institute of Oceanography, Dona Paula, Goa-403 004) : Sea level during storm surges as seen in tide-gauge records along the east coast of India. Curr Sci 1999, 77(10), 1325-32.

Analysis of hourly sea level recorded by tide gauges of the Survey of India (SOI) at Paradip, Vishakhapatnam, and Chennai provides a record of non-tidal sea level during three periods, 6-10 August 1979, 6-10 August 1981, and 24-27 September 1981, when storms formed over the Bay of Bengal and crossed the east coast of India. During each event, the impact was largest at Paradip and weakest at Chennai. In the first event, the sea level at Paradip was depressed, whereas there was a surge during the second and third events. The analysis shows that historical SOI tide-gauge data would be useful for testing the numerical models that are now emerging as an important component of defence from storm surges in the bay.

009720   Sinha U N;Nanjundiah R S;Venkatesh T N (Flosolver Unit, National Aerospace Laboratories, Bangalore-560 017) : Computational weather modelling. Curr Sci 1999, 77(10), 1333-42.

There have been major advances in the field of weather prediction by numerical methods, since the 1920s. The details of modelling the atmosphere along with the computational techniques are discussed. Some outstanding problems in the Indian context are highlighted.

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009719   Singh S P;Anil Kumar;Uday Kumar;Sinha J (NO, Veer Kunwar Singh University, Ara) : Primary source material of the amphibolites of Chuttupalu area, Ranchi (Bihar): a statistical approach. Aryabhata Res J phys Sci 1998, 1, 1-6.

amphibolites of the Chuttupalu area occur as enclaves in chotanagpur granite gneiss and also as massive bodies of varying dimensions. Mineralogically, It is a horn-blende-plagioclase (labradorite and / or andesine) bearing rock with diopside, biotite, garnet, apatite, sphene and opaques occuring as accessories. The compartmentalisation of amphibolites of the present area into ortho/para has been attempted with the help of established and globally tested geostatistical tools. The geostatistical tools have been found to be very effective in establishing the parentage of the amphibolites of the chuttuapalu area. The ortho nature of these amphibolites has been confirmed due to their positive Cr/Ni and Sr/Ba ratios. The oxidation ratio value and the linear discriminant functions is X1, X2 and X3 values of these rocks is also an evidence in support of igneous origin for them.

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009718   Singh R K (NO, ICAR Research Complex for NEH Region, Sikkim Centre, Tadong-737 102) : Weather variations in the mid hills of Sikkim - a case study of Tadong area. J Hill Res 1999, 12(2), 151-3.

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009717   Singh O P (NO, Meteorological Centre, Bhubaneswar) : Radius of influence of a vortex. Mausam 1999, 49(4), 439-42.

Using the pressure profile in and around a vortex tube a simple relation for the radius of influence of the vortex has been derived. The results have been applied to assess the region of maximum devastation in a tornado. The analysis reveals that the occurrence of `eye wall' region in a tropical cyclone is a hydrodynamical phenomenon.

009716   Singh O P (NO, Meteorological Centre, Bhubaneswar) : Sea surface temperature and sea level pressure anomalies over the Arabian sea during ENSO year. Mausam 1998, 49(2), 264-6.

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009715   Singh O P (NO, Meteorological Centre, Bhubaneswar) : Bay of Bengal cyclone cluster of November 1992. Mausam 1998, 49(2), 173-6.

Cyclone cluster that formed over the Bay of Bengal during November 1992 has been looked into in relation to ses surface temperature (SST) distribution obtained from 1° x 1° grid averages remotely sensed by NOAA-AVHRR. Examination of weekly SSTs has revealed that entire Bay of Bengal north of 8°N was unusually warmer about a week before the formation of the cyclone cluster. As a matter of fact, during the above period the SST for each of the 60 grids over the sea area between 13°-21° and 81°-90°E exceeded 30°C. Widespread cooling of the sea was noticed just before the commencement of cyclogenesis.

009714   Singh G P;Chattopadhyay J (Deptt. of Geophysics, Banaras Hindu University, Varanasi-221 005) : Influence of some circulation anomalies on Indian northeast monsoon rainfall. Mausam 1999, 49(4), 443-8.

Relationship between Indian northeast monsoon rainfall over Tamil Nadu (TNR) and southeast India (SER) as well as two indices of southern oscillation (SOI), and sea surface temperature (SST) anomalies over different Nano regions of equatorial Pacific Ocean and seven tropical circulation indices (TCI), have been studied for different periods. The study indicates that northeast monsoon rainfall (TNR) shows significant inverse relationship with SOI (I-D) during previous MAM (March-April-May) season, significant direct relationship with SST anomaliesover Nino-4 region during previous JJA (June-July-August) and significant direct relatioship with TCI (C-N) during previous DJF. The SOI (I-D), MAM correlates significantly and negatively with both the northeast monsoon rainfall series, the TNR rainfall series displaying the better correlation. The strongest correlation is observed during 1961-90. For SSTA, the strongest correlation is during 1964-85 and for TCI, the highest correlation is observed during 1958-82.

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009713   Shirodkar P V;Somayajulu Y K;Sarma Y V B; Vijayakumar R (NO, National Institute of Oceanography, Dona Paula, Goa-403 004) : Hydrographic characteristics of the Indian sector of the Southern ocean. Curr Sci 1999, 77(10), 1273-82.

Surface layer (50 m) of summer surface water formed by seasonal warming with temperatures (0-2°C) and low salinity (<60> 33.8 PSU), the intermediate layer (50-150 m) of winter reminiscent water with negative temperatures (0 to -2°C) and moderate salinity (33.8-34.3 PSU) and the deeper layer (below 150 m) of Circumpolar Deep Watermass (CDW) with positive temperatures (0-2°C and higher salinity (34.3-34.8 PSU). The influence of the strong Antarctic Divergence between the east and west drifts is noticed at 61°S, 34°E marked by phytoplankton and zooplankton patches. The dissolved oxygen (DO) shows high concentrations (7.6 to <62>8.0 ml l^-1) in the upper layer. These higher levels of DO sometimes extend down to the intermediate layer and gradually decrease further downwards. The observed low temperature and high DO in the subsurface water (50-75 m) are typical signatures of Antarctic Winter Watermass (AWW) formed during winter. Calcium, magnesium and boron show significant spatial variations with higher values of Ca and Mg along 59°S and 60°S relative to 61°S. Ca exhibits large variations (398-421 mg kg^-1 while Mg shows least variations with concentrations close to the average value for normal sea water (1294 mg ka^-1).....

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009712   Satapathy K K;Jena S K;Daschaudhuri D;Bundela D S (NO, ICAR Research Complex for NEH Region, Umroi Road, Umiam-793 103) : Climate and its variation at Umiam, Meghalaya. Indian J Soil Conserv 1999, 27(2), 166-70.

009711   Saha K;Saha S (NO, , 27, B-Road, Maharani Bagh, New Delhi-110 065) : Role of tropical mid-latitude interaction in the genesis of a monsoon depression - a detail case study. Mausam 1998, 49(2), 159-66.

During northern summer, a monsoon stationary wave which maintains as part of its baroclinic structure three well-defined troughs, one each in the region of the Arabian sea, the Bay of Bengal and South China sea, frequently interacts with the mid-latitude baroclinic waves which amplify during their eastward passage with profound influence on the development of the monsoon troughs. Discusses the mechanism of this wave-wave interaction as suggested by the temporal evolution of the thermal and wind fields associated with the waves and reports the findings of a detailed study of a case of tropical-midlatitude interaction in which the development of a monsoon trough led to the birth of a westward-propagating monsoon depression over South China.

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009710   Ray K;Sahu M L (NO, Flood Meteorological Office, Meteorological Centre, Ahmedabad-380 003) : Synoptic analogue model for QPF of river Sabarmati basin. Mausam 1999, 49(4), 499-502.

Attempt has been made to prepare a model for issuing semi quantitative precipitation forecast for river Sabarmati by synoptic analogue method. The model is based on 10 years (1986-95) of data. The QPF issued by the model is verified with the WAR of years 1995 of years 1995 and 1996. The performance of model was good. This model can be used confidently for issue of QPF for Sabarmati basin.

009709   Rakhecha P R;Kulkarni A K;Mandal B N;Sangam R B;Deshpande N R (NO, Indian Institute of Tropical Meteorology, Pune-411 008) : Probable maximum precipitation for the catchment of Koyna dam. Mausam 1998, 49(2), 211-6.

Estimates of probable Maximum Precipitation (PMP) for different durations were made for the catchment above Koyna dam on the Koyna river. The catchment spans an area of 892 km² and the PMP estimates were made for a range of durations of 1 to 3 days. The PMP estimates for Koyna dam were found to be 48.87 and 117 cm by the physical method and 54,89 and 124 cm by statistical method for 1, 2 and 3 day respectively. These estimates can be used to check the existing spilway design flood of Koyna dam.

009708   Rajendra Kumar J;Balachandran S;Bhosale S G (NO, Meteorological Office, Pune-411 005) : Onset of northeast monsoon - a case study. Mausam 1999, 49(4), 521-4.

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009707   Rajeevan M (NO, Meteorological Office, Pune-411 005) : Aerosol - cloud - climate effect: study with a radiative transfer model. Mausam 1998, 49(2), 195-202.

Indirect radiative forcing (through the enhancement of cloud albedo) due to anthropogenic sulphate aerosols was calculated using a three-dimensional rediative transfer model. The calculations were made with diurnal and seasonal cycles and three-dimensional distributions of sulphate aerosol concentration data. the globally averaged annual mean indirect forcing is estimated to be - 1.13 Wm^-2 which is comparable with the recent General Circulation Model calculation. This forcing of -1.13 Wm^-2 is compared with 2.12 Wm^-2 due to increase in greenhouse gases from the pre-industrial period to the present. This indirect forcing due to anthropogenic aerosol is substantially higher than the warming effect due to greenhouse gases over the industrial regions in the northen hemisphere, so that the net radiative forcing over these regions is negative, i.e. cooling. Some uncertainties in the estimation of the indirect forcing that needs further research are pointed out.

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009706   Raj Y E A (NO, Regional Meteorological Centre, Chennai) : Scheme for advance prediction of northeast monsoon rainfall of Tamil Nadu. Mausam 1998, 49(2), 247-54.

Monthly means of winds, contour height and temperature of seven standard isobaric levels of ten well distributed Indian upper air stations for the months of April, June, July, August and September were subjected to correlation analysis to detect parameters that have predictive value to forecast in advance the northeast monsoon rainfall of Tamil Nadu. The period 1965-87 was taken as developmental period and 1988-94 as test period. Six predictors, out of which three were completely new, were identified. The final forecast of rainfall was obtained as the weighted average of the individual forecasts based on the six predictors by employing a screening technique different from the conventional ones. The system explained between 65-77% variation of the predictand with standard error of 13-18% and provided reasonably correct forecasts during the test period. The physical significance of the predictors has been explained based on the intensity of the subtropical anticyclone over India. The possibility of extending the study to include global parameters in the context of proven negative and significant relationship between Southern Oscillation Index (SOI) and the Indian northeast monsoon has been discussed. Scope for further studies on the topic has been spelt out.

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009705   Pai D S;Rajeevan M;De U S (NO, Meteorological Office, Pune-411 005) : Upper troposphere circulation anomalies over Asia-Pacific region associated with the interannual variation of Indian summer monsoon. Mausam 1999, 49(4), 461-8.

Monthly mean vector wind and geopotential heights at 200 hPa of 67 radiosonde stations from Asia Pacific regions for the period 1963-1988 are used to examine the composite circulation anomaly patterns for the month of May and the monsoon season (June-September) with respect to good monsoon years and had monsoon years (both associated with ENSO and not associated with ENSO). There are significant differences in the anomalous circulation features between good and bad monsoon years. During the month of May an anomalous anticyclonic (cyclonic) circulation over-central Asia and an anomalous cyclonic (anticyclonic) circulation over Pacific ocean were observed during good (bad) monsoon years. These anomalies persist in the subsequent monsoon season. The key mechanism of the development of these anomalous circulation patterns and their consequences are discussed.

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009704   Ojasvi P R;Panda R K (NO, Central Arid Zone Research Institute, Jodhpur) : Long-term trends and periodicities in the daily rainfall sequences over upper Mahanadi basin. Mausam 1998, 49(2), 259-62.

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009703   Mishra P J;Dash S K;Behera B D;Sahu D (Integrated Watershed Development Project (Research), Orissa University of Agriculture and Technology, Phulbani-762 001) : Evaluation of vegetative barriers for soil moisture conservation and sustained land productivity. Indian J Soil Conserv 1999, 27(2), 177-9.

009702   Mishra A K;Sarkar T K;Bhattacharya A K (SWCE, Water Technology Centre, Indian Agricultural Research Institute, New Delhi) : Stochastic rainfall forecasting for weekly water resource assessment in lower Assam. Indian J Soil Conserv 1999, 27(2), 99-111.

Long term rainfall records of Kokrajhar and Dhubri (Assam) and Cooch-Behar (W.B.), were subjected to statistical analysis and probability distribution. A range of homogeneous probability distributions were fitted in meteorological weeks in active monsoon period. The most appropriate probability distributions were attributed to weekly rainfall amounts of 35, 10 and 10 years long data records of Kokrajhar, Dhubri and Cooch Behar, respectively using VTFIT-subroutine (Coocke, 1993). The most appropriate probability distribution was assigned to a particular meteorological week. The probability density functions were then used to forecast weekly rainfall amounts at different probability levels of equalling or exceedance. Weekly water resources of the area in terms of rainfall occurrences were assessed with the help of these stochastic predictions of rainfall. The analysis helped in formulating the guideline for allocating water to various crop grown in the study region.

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009701   Lamba B S;Bhandari S (NO, Meteorological Office, Pune-411 005) : Some aspects of thermal diffusivity for various soil layers in different harmonics. Mausam 1998, 49(2), 255-8.

Values of thermal diffusivity (K) in different soil layers for the first three harmonics have been computed for six stations in the dry farming tract of India by using amplitude ratio and phase lag. In general, the combined effect of all these harmonics gives the values of K close to the order of the experimental values. It is found that the theory of simple heat conduction is not applicable to soil medium. While the lowest values of K in all the harmonics are found at Rajahmundry, the highest values are observed at either Hissar or Bhubaneshwar for the first two harmonics and at Pantnagar for the third harmonic. Strong annual and bi-annual cycles dominate at Hissar, Pantnagar and Bhubaneshwar while quarterly cycle is significant only at Pantnagar.

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009700   Lakshminarayanan R (NO, Meteorological Centre, Thiruvananthapuram-695 033) : Interaction of an easterly system with westerly and its associated weather over southern Peninsula. Mausam 1999, 49(4), 449-52.

During the week 11-17 April 1996 southern Peninsula received good rainfall especially with heavy rainfall on 13 and 15 April 1996 in Tamilnadu making the seasonal rainfall from 1 March to 17 April 1996 into large excess in south interior Karnataka and excess in Tamilnadu and north interior Karnataka. An attempt is made to investigate the synoptic situations leading to the large excess rainfall over these area during the week 11-17 April 1996.

009699   Lakhan Singh;Sinha B P;Rao D U M (NO, Central Soil and Water Conservation Research and Training Institute, Dehra Dun - 248 195) : Water distribution system in Bawani: a case study of internal initiative and efficacy. Indian J Soil Conserv 1999, 27(2), 184-5.

009698   Kumar P;Singh M P;Natarajan A N (Faculty of Meteorology, Air Force Admn. College, Coimbatore) : Analytical model for mountain wave in stratified atmosphere. Mausam 1999, 49(4), 433-8.

Analytical, two-dimensional computer model has been developed for real time prediction of mountain wave due to Pirpanjal mountains over Kashmir Valley. simulation of the L² profile has been made with realistic, non-zero values at higher levels and exponentially decreasing values at lower levels. Unlike Doos (1961), present solution has no restriction on the value of wave number (κ). Validity of the model has been tested with the satellite observed waves in seven cases and actual aircraft report in one case.

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009697   Kashyapi A;Shaha S K;Gulhane P M (NO, Meteorologial Office, Pune-411 005) : Sudden changes in crop environments, as influenced by total solar eclipse. Mausam 1999, 49(4), 511-20.

Division of Agricultural Meteorology, at Pune of IMD conducted an experiment at Principal Evapotranspiration Observatory, Canning, W.B., during October, 1995 to study the sudden changes in crop environment. The study revealed that both the crop canopy temperature and observatory temperature at different heights recorded sharp fall of around 2.0°C at 0900 hr (IST) on the eclipse day. The relative humidity (%) increased sharply at 0900 hr (IST) on the eclipse day within crop canopy as well as within observatory. The soil temperature dropped suddenly at 10 and 20 cm depths of the subsoil and delayed reversal of the soil temperature gradient occurred on the eclipse day; the grass minimum temperature was 21.2°C. Bright sunshine hours reduced by 0.8 on the eclipse day as compared to the preceding and succeeding days. The wind during the eclipse period was almost calm between 0900 - 0930 hr (IST). The daily total ET recorded on the eclipse day was the minimum. The rate of evapotranspiration was less than half as compared to the other days, as recorded at 0830 hr (IST) (0.2 mm) on the eclipse day, which was closely followed by that observed at 1130 hr (IST) (0.3 mm).

009696   Karmakar S (Bangladesh Meteorological Department, , Dhaka, Bangladesh) : Vertically-integrated tropospheric moisture, energy and their fluxes over Bangladesh during landfall of tropical cyclones. Mausam 1998, 49(2), 187-94.

Changes in the vertically-integrated tropospheric moisture, energy and their fluxes over Bangladesh have been studied during the landfall of three major cyclones at Bangladesh coast in the recent past. It has been found that the vertically-integrated tropospheric moisture, dry static energy, latent energy and total energy over the country have a tendency to decrease at the formation stages of the cyclones in the Bay of Bengal and then the same shows significant increase as the cyclones move northwards for ultimate landfall. The integrated zonal and meridional fluxes of moisture, dry static energy, latent energy and total energy exhibit significant changes both in magnitudes and signs during the northward movement of the cyclones.

009695   Kar I;Bondhyopadhyay R (NO, Regional Meteorological Centre, Calcutta) : Climatological study of premonsoon thunderstrom over Sriniketan, Alipore and Kalaikunda. Mausam 1998, 49(2), 262-4.

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009694   Kane R P (NO, Instituto Nacional de Pesquisas Espaciais - INPE, Caixa Postal 515-11201-970, Sao Jose dos Campos, SP, Brasil) : Comparison of quasi biennial oscillations of stratospheric winds and atmospheric temperatures at different altitudes. Mausam 1998, 49(2), 223-8.

During 1959-89, the 12-month running means of 50hPa zonal winds, the average atmospheric temperatures in the northern and southern hemisphere at four altitude slabs (950hPa, 850-300hPa, 300-100hPa and 100-50HPa), Pacific and Atlantic sea surface temperature (SST) and 30hPa temperatures at North Pole and average for (10°-90°N), all showed quasi-biennial oscillations (QBO). However, whereas the wind QBO had an average spacing of 29 months, only temperatures at 300-100hPa and Atlantic SST had similar average spacing. Other temperatures as also SO index (represented by Tahiti minus Darwin atmospheric pressure) had larger average spacing. Spectral analysis showed that whereas wind QBO had only one prominent peak at T=2.33 years, other parameters had weak QBOs near T=2.5-2.6 years except Pacific SST and 30hPa North Pole temperature which had small peaks near T=2.3 years. All the temperatures had prominent peaks in the 3-6 year region which matched with similar peaks in the SO index. There is some indication that stratospheric wind QBO had some relation with parameters at all altitudes in tropics and with North Pole, while ENSO had considerable influence at other latitudes/altitudes.

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009693   Kandalgaonkar S S;Tinmaker M I R;Manohar G K (NO, Indian Institute of Tropical Meteorology, Pune-411 008) : Initial development of precipitation and onset of cloud electrification in thunderstorms at Pune. Mausam 1999, 49(4), 481-6.

Using one-minute interval data of electric field and the records of rainfall measured at the ground surface, time sequence in the initial registration of precipitation and the onset of cloud electrification was examined for a series of 14 thunderstorms of the year 1973 at Pune to study the relationship between the initial development of precipitation and intensification of cloud electrification. The combined result of the 14 storms studied, each of which yielded precipitation, indicated in-cloud development of precipitation at least 3-7 minutes in advance of onset of cloud electrification. It is inferred from the other supplementing studies published by other workers and from the above result that in most cases the precipitation development in thunderstorms is initiated well before the electric field begins to intensity. This result is in close agreement with the result of previous studies.

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009692   Jayanthi N;Asokan R (NO, Meteorological Office, Chennai) : Some thermodynamic implications of microburst forecasting over Madras airport. Mausam 1999, 49(4), 525-7.

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009691   Gore S D;Nasiri P (Deptt. of Statistics, University of Pune, Pune-411 007) : Four statistical models for wet-spell analysis. Mausam 1999, 49(4), 493-8.

Wet-spell analysis is an important part of rainfall analysis. The distribution of the length of wet-spells provides useful information on the temporal distribution of ranfall. This distribution has traditionally been modelled through different probability distribution. Compare four such models, namely, Cochran's model, truncated Poisson distribution, truncated negative binomial distribution, and logarithmic series distribution. These comparison are accomplished with help of application to five rainguage station in India.