021532   Chakraborty D R;Agarwal N K (NO, Indian Institute of Tropical Meteorology, Pune-411 008) : The role of high and low frequency dynamics during the two contrasting monsoon years. Proc TROPMET Natl Symp 2001, (NULL), 323-8.

Deals with computational modeling designed to understand the role of high and low frequency dynamics during the two contrasting monsoon years that results from nonlinear energy transfer mechanism in the frequency domain. The study is performed for the summer months June, July, August and September of 1987 and 1988 at 850 hPa and 200 hPa over the latitudinal belt 20°S - 30°N. The energy exchanges among different frequencies and the interactions between the transient eddies and the seasonal mean flow are found to be an order of magnitude smaller during bad monsoon year 1987 than those during good monsoon year 1988. The dominant low frequency intra-seasonal monsoon modes are found to depend on the strength of upper tropospheric easterly jet. Analysis of triad energy interactions in the frequency domain reveals that nonlinear energy transfer among the large scale monsoon, transient circulation associated with intra-seasonal oscillations and the high frequency synoptic time scale waves is a viable dynamical mechanism for good summer monsoon.

8 illus, 4 ref

021531   Chakrabatry D;Pant T K;Sekar R;Taori A;Modi N K;Narayanan R (Physical Research Laboratory, , Ahmedabad-380 009) : Thermospheric temperature and magnetic field measurements from Mt Abu during a geomagnetically disturbed period. Curr Sci 2002, 83(2), 167-70.

During the recovery phase of a `moderate' geomagnetic storm, spectroscopically measured night-time thermospheric temperatures from Mt Abu (24.6°N, 73.7°E, dip 19.09°) are found to deviate considerably (<126>)200-600 K) from the MSIS-90 model temperatures on many occassions, implying the model's limitations as applied to low-latitude thermosphere. The measured temperatures exhibit oscillatory features as opposed to the flat, featureless temperature profiles rendered by the MSIS-90 model temperatures on many occasions, implying the model's limitations as applied to low-latitude thermosphere. The measured temperatures exhibit oscillatory features as opposed to the flat, featureless temperature profiles rendered by the MISIS-90 model. The temperature variabilities are found to succeed the variations in the time rate of change of the total magnetic field measured by a standard Proton Precession Magnetometer by <126> 12.5 h, revealing the `response time' of the low-latitude thermosphere to the disturbances over higher latitudes.

2 illus, 15 ref

021530   Brij Bhushan (National Informatics Centre, , New Delhi) : Measuring intensity of cyclones using sea wave height. Proc TROPMET Natl Symp 2001, (NULL), 74-81.

Direct measurement of intensity of cyclones in terms of wind speed and pressue are difficult as the anemometers in the observatories, automatic weather stations and buoys on the ocean are blown off and ships avoid going into the storms. Also the eye of the storm need not pass over an observing station. Dvorak's method is the standard for tropical cyclones intensity measurement while some countries use aircraft reconnaissance. Aircraft observations are extremely expansive and require specialized technology and skill to fly into the cyclones for observations. Beauferts scale for correlating winds and ocean roughness, the Saffir-Simpson scale for hurricanes' intensity and Fujta-Pearson scale for tornadoes are based either on the sea/land surface conditions at the time of observation or damages left behind by the storm. Sea wave height, if measured accurately, can become a standard for measuring the intensity of storms particularly at the time of its landfall. It is possible to measure wave height if an instrument with proper scaling and telemetry is installed on the shallow coastal sea bed or on a moored platform at a reasonable depth in the ocean. Describes a low cost observing system for measuring the intensity of a cyclone, particularly at the time of its crossing the coast.

3 tables, 10 ref

021529   Biswas B (Meteorological Office, C S I Airport, Mumbai-400 099) : A study of poor visibility over Chhatrapati Shivaji International airport, Mumbai due to heavy monsoon rain. Proc TROPMET Natl Symp 2001, (NULL), 516-19.

An attempt has been made to study the poor visibility condition over Chhatrapati Shivaji International (C.S.I) airport, Mumbai due to heavy rain during southwest monsoon season. It is observed that due to heavy rain horizontal surface visibility reduces to below minima and low clouds some down. This disrupts all types of flight operations. The poor visibility occurs more frequently in the morning hours of the day. Among the different monsoon months, July experiences the maximum number of occurrences of poor visibility. The most of the occurrences of poor visibility condition are of short duration. The persistence of poor visibility for long duration is associated with significant synoptic situation.

2 tables, 3 ref

021528   Bhatia R C;Singh D;Mukherjee S K (India Meteorological Department, , Lodi road, New Delhi-11003) : Validation of ocean surface wind speed and water vapour derived form multi-channel scanning microwave radiometer (MSMR) onboard Indian Remote Sensing satellite (IRS-P4). Proc TROPMET Natl Symp 2001, (NULL), 396-401.

The MSMR payload launched onboard Indian Remote Sensing satellite, IRS-P4 in May, 1999 is providing ocean surface wind speed and total perceptible water vapour over the oceanic areas. These data products were made available to IMD by SAC in near-real time during Monsoon seasons of 2000. An attempt has been made for detailed validation of these products by comparing them with similar products derived from SSM/I onboard F-13/14 and TMI onboard TRMM satellites of the USA. Match up co-located data sets were prepared for one month period and statistical analysis done. The rmse of water vapour is found to be 0.53 gm/cm² (MSMR and SSM/I) and 0.32 gm/cm² (MSMR and TMI) with a bias of -0.35 gm/cm² (MSMR and TMI). For wind speed, however, errors are little higher. RMSE of wind speed is 3.12 m/sec (SSM/I and MSMR) and 2.30 m/sec (TMI and MSMR) with a bias of -1.54 m/sec (SSM/I and MSMR) and -0.45 m/sec (TMI and MSMR). Fine tuning of regression coefficients is necessary for further improving the MSMR derived wind speed. MSMR derived water vapour is of good quality and it can be used for meteorological applications.

2 illus, 4 ref

021527   Bhatia R C;Khanna P N;Singh D;Mukherjee S K (India Meteorological Department, , Lodi Road, New Delhi-110 003) : Recent improvements in the quality of INSAT derived cloud motion vectors (CMVs). Proc TROPMET Natl Symp 2001, (NULL), 389-95.

Certain vital changes have been incorporated during the period 1st November, 1999 to 1st February, 2000 in the INSAT CMV derivation scheme. It is operational at INSAT Meteorological Data Processing System (IMDPS) for providing satellite derived winds of improved quality to the users. The changes include improved height assignment technique, better navigation of images, use of Limited Area Model forecast field in quality control and minor bias adjustments of derived wind vectors before dissemination on GTS. As a result of these changes the quality of operational CMVs has now improved considerably as compared to the period prior to 1st November, 1999. RMSE of high and medium level CMVs has now reduced from 10m/sec to about 5.5. m/sec. BIAS has also reduced from 10m/sec to less than 1m/sec. Low level CMVs have also improved. These improvements in quality of operational CMVs and have found them useful for their routine operations.

2 illus, 7 ref

021526   Bhatia R C;Jain R K;Meena L R (India Meteorological Department, , Lodi Road, New Delhi-110 003) : Potential use of MSMR data received from IRS-P4 for forecasting heavy rainfall events over Indian coastal areas. Proc TROPMET Natl Symp 2001, (NULL), 402-7.

The microwave radiometer launched on board IRS-P4 Indian Remote sensing statellite in May, 1999 has started providing good quality quantitative products to supplement conventional meteorological data, particularly over data sparse ocenic regions. The data on ocean surface wind speed and total precipitable water vapour over oceanic areas has been found to provide useful signals for diagnosis of the areas of moisture convergence giving rise to heavy rainfall over coastal areas if a lifting mechanism is present. This data when used in conjunction with other conventional observations, can provide better insight into antecedant conditions prior to development of heavy rainfall. In particular, analysis of 2 cases of heavy precipitation during Pre-monsoon and south west monsoon seasons of the year 2000 has shown that when areas of high total percipitable water become aligned with the ridge axis of equivalent potential temperature and a lifting mechanism is present, heavy rainfall occurs. MSMR data products are, therefore, potentially useful for meteorological applications.

12 illus, 4 ref

021525   Bhaskar Rao D V;Naidu C V (Department of Meteorology and Oceanography, Andhra University, Visakhapatnam) : Some observational and modelling aspects of Tropical Cyclones over Bay of Bengal. Proc TROPMET Natl Symp 2001, (NULL), 27-37.

7 illus, 1 table, 7 ref

021524   Bawiskar S M;Mujumdar V R;Singh S S (Indian Institute of Tropical Meteorology, , Pune-411 008) : Influence of premonsoon westerlies over south Indian ocean on AIMR. Proc TROPMET Natl Symp 2001, (NULL), 206-10.

Monthly zonal (u) and meridional (v) components of wind at 850 hPa between 30°S and 30°N are extracted from the ECMWF reanalysis field for fifteen years (1979-1993) and subjected to Fourier analysis. The analysis shows that the zone of westerlies in March over the south Indian ocean influences the summer (June through September) monsoon circulation (rainfall activity) over Indian region through its annual meridional oscillation. A strong zone of westerlies in Indian ocean during March, has indicated a good monsoon season for the country. Similarly a momentum transport of wave zero observed over latitudianl belt between 25°S and 5°N during March has shown a positive correlation (1% level of significance) with All India Monsoon Rainfall (AIMR). The northward (southward) momentum transport of wave zero observed in March over the belt has subsequently led to a good (drought) monsoon season over India even when the year has been marked with the El-Nino event. The detailed study is expected to show that the momentun transport will be a good predictor of AIMR.

3 illus, 1 table, 4 ref

021523   Bawiskar S M;Chipade M D;Singh S S (Indian Institute of Tropical Meteorology, , Pashan Road, Pune-411 008) : Energetics of zonal waves during different phases of monsoon. Proc TROPMET Natl Symp 2001, (NULL), 211-14.

Energetics of lower tropospheric zonal waves during onset, established and withdrawal phases of monsoon have been studied. It is found that region R1(10°S-10°N) is dominated by zonal mean flow (wave 0), region R2 (10°N-30°N) is dominated by long waves (wave 1-2) and region R3 (30°N-50°N) is dominated by short waves (waves 3-10). Strengthening (Weakening) of wave 0 over R1 and long waves over R2 results in the strengthening (weakening) of monsoon activity over India while strengthening (weakening) of short waves over R3 results in the weakening (strengthening) of monsoon activity over India. The weekly analysis of the energetics of zonal waves indicates that the momentum transport of wave 0 over latitudinal belt L0 (12°S-3°N), wave 1 over the belt L1 (10°N-15°N) and wave 2 over the belt L2 (33°N-45°N) are related to all India rainfall on a weekly scale. Larger southward momentum transport of wave 0 over L0 and larger northward momentum transport of wave 1 over L1 and wave 2 over L2 enhance the monsoon activity over India.

2 illus, 1 table, 5 ref

021522   Basu S (Nitrogen and Noble Gas Mass Spectrometry Laboratory, Planetary and Geosciences Division, Physical Research Laboratory, Ahmedabad-380 009) : Earth's mantle composition - present understanding. Curr Sci 2002, 83(2), 111-3.

^ssc1 illus, 1 ref

021521   Banerjee B;Shaw R K (Marine Wing, Geological Survey of India, , 4 Chowringhee Lane, Kolkata-700 016) : Marine magnetic anomalies near the barren Island volcano, Andaman sea. Curr Sci 2001, 81(7), 816-18.

Marine magnetic anomalies along two EW profiles near the Barren Island volcano in Andaman Sea have been analysed in shorter segments, for computation of source depths. The depths to the deepest source in individual segments have been used to map the bottom of the magnetized crust. Characteristic differences between the patterns of magnetic anomalies along the eastern and western side of Barren island suggest that magma conduits in the eastern side are ransomly distributed. Time-lapse marine magnetic measurement over a profile has been used to estimate upward migration of the bottom of the magnetized crust in this region.

3 illus, 18 ref

021520   Babu C A;Joseph P V (Department of Atmospheric Sciences, Cochin University of Science and Technology, Cochin-682 016) : Association between the Indian summer monsoon rainfall and the 200 hPa Wind field 1961-90. Proc TROPMET Natl Symp 2001, (NULL), 156-65.

Studies the relation between 200 hPa wind field and the Indian Summer Monsoon Rainfall (ISMR) of June to September. It is found that the mean zonal wind at 200 hPa in an elongated area from Japanese Islands to the north American coast between latitudes 30 and 50 degrees north during the winter season December to March (seasonal mean) is significantly correlated to the ISMR of the following summer. Joseph et al (1981) had shown the high correlation between 200 hPa meridional wind over India in the month of May (monthly mean) and the following ISMR. Mean sea level atmospheric presure tendency from winter to spring of bombay is also significantly correlated tot he following ISMR (Parthasarathy et al, 1991). These correlations are also large in magnitude. The multiple correlation of these three factors with the following ISMR using data of 30 years 1961 to 1990 is obtained as 0.84. These three factors of the prior winter and spring seasons together thus explain about 70 percent of the variance of monsoon rainfall of India.

4 illus, 3 tables, 12 ref

021519   Anthricta;Kunhikrishnan P K;Krishnan P; Muraleedharan Nair S (Space Physics Laboratory, Vikram Sarabhai Space Centre, Thiruvananthapuram-695 022) : Observation of atmospheric boundary layer structure in a tropical Inland station during pre-monsoon period using wind profiler observations. Proc TROPMET Natl Symp 2001, (NULL), 367-76.

Lower Atmospheric Wind Profiler (LAWP) established at National MST Radar Facility (NMRF), Gadanki is a very useful tool for lower atmospheric wind and turbulence studies. LAWP data collected during the period March to July 98 is analysed to study the boundary layer structure during these months. Evolution of atmospheric boundary layer can be very clearly seen using the data collected during the clear air conditions. The atmospheric boundary layer depth goes upto 2 km during convective condition. Elevated layer structure and night time stable structure can be seen from radar reflectivity plot. The wind speed values reach upto 10 m/s during March months. Winds are easterly during March and wind direction change to westerly by middle of May. During May maximum wind speed reach upto 15-20 m/s within the boundary layer at Gadanki.

5 illus, 3 ref

021518   Anil Kumar;Rajagopalan G (NO, National Geophysical Research Institute, Hyderabad-500 007) : Age of the lower vindhyan sediments, central India. Curr Sci 2001, 81(7), 806-09.

Basic issue raised by the two simulataneous and sensational reports^1,2 in 1998 of body fossil evidence (worm tracks and small shelly fauna, respectively) of multicellular life in the Lower Vindhyan sediments, in the true age of the latter. Is the true age Mid-proterozoic as believed so far, on limited geochronological data. Or is it only Early Cambrian, as was argued by Azmi² and supported by a single preliminary Ar-Ar age of 617 Ma measured soon after the reports" Although both the fossil evidences are now equivocal, the basic issue remains. Reports consistent Rb-Sr ages for glauconies from the Lower Vindhyan sediments (Semri Group) near Chitrakut, which constrain the onset of the earliest Vindhyan sedimentation to not later than 1600 Ma. Considering other available chronological constraints, the Vindhyan basin is likely to preserve a rare, very long and least disturbed recored of Pre cambrian sedimentation.

2 illus, 2 tables, 24 ref

021517   Anand S P;Rajaram M (Indian Institute of Geomagnetism, , Colaba, Mumbai-400 005) : Aeromagnetic data to probe the Dharwar craton. Curr Sci 2002, 83(2), 162-7.

Degree-sheet aeromagnetic maps of Dharwar craton were digitized closely along contours and re-gridded at 2.5 km interval to obtain an image map, after removal of International Geomagnetic Reference Field. The total field anomaly and generated analytical signal maps confirm the division of Dharwar cration into western and eastern blocks, and are consistent with the several strike trends of the causative sources. The Chitradurga schist belt appears to divide the Dharwar craton into the western and eastern blocks. It has been found that the density of the anomalies in the Eastern Dharwar is greater than that in the Western Dharwar. This may be explained by either or a combination of the following: higher grade of metamorphic rocks in the Eastern Dharwar or the Eastern block may be uplifted with respect to the Western block with the characteristics of the deeper crustal layer now exposed due to erorsion or presence of thick sedimentary sequence in the Western with volcanic in the Eastern.

3 illus, 12 ref

020510   Virk H S;Sharma A K;Sharma N (Department of Physics, Guru Nanak Dev University, Amritsar-143 005) : Radon and helium monitoring in some thermal springs of North India and Bhutan. Curr Sci 2002, 82(12), 1423-4.

1illus, 2 tables, 12 ref

020509   Venkataraman S (NO, , 59/19, Navsahyadri Society, Pune-411 052) : Simple and rational agroclimatic method for rainfall zonations in dryland areas. Indian J Envir Ecoplann 2001, 5(3), 431-6.

Necessity for delineation of homogenous rainfall zones for the projects on fitting-t-Climate and monitoring of rainfed crops is highlighted. The lack of rationale and uniformity in existing methods for rainfall amounts are brought out. An appropriate methodology using mainly data on rainfall amounts at 30% and 50% probability levels is splet out Application of the criteria to published rainfall probability data for a large number of stations covering the Dryfarming Tract to delimeate homogenous rainfall zones is suggested. The uses to which such zonations can be put to are indicated.

3 tables, 15 ref

020508   Validiya K S (Geodynamics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore-560 064) : Reactivation of terrane-defining boundary thrusts in central sector of the Himalaya: implications. Curr Sci 2001, 81(11), 1418-31.

The central sector of the Himalaya is under very strong comprssive strain. Almost all thrusts that define the boundaries of lithotectonic terranes of the Kumaun Himalaya are active. The fault reactivation is expressed in different geomorphic developments and drainage responses. In the north, neotectonic movements along the fault zone, that caused detachment of the Great Himalayan crystalline foundation from the Tethyan sedimentary pile, have resulted in formation of lakes upstream of points of the fault crossings and in the development of deep gorges downstream. Confirmed to the inner Lesser Himalaya in the middle of the Himalayan domain, are stepped terraces lining valleys upstream of the reactivated Almora Thrust, implying commonly three pulses of uplift in the late Quaternary time. The synclinal nappe of the crystalline rocks bound by the Almora Thrust is an active fold. In the south, reactivation of faults of the schuppen zone of the Main Boundary Thrust is evident from the pronounced dextral swing of antecedent rivers, the truncation of colluvial cones and fans in the fault zone, and the valley-fills upstream of points of the faults that cross them. In the foothills, Holocene movements along the Himalayan Frontal Fault have considerably uplifted and tilted the late Pleistocene-to-early Holocene gravel deposits covering the Siwalik terrane.

20 illus, 64 ref

020507   Thorat P G (NO, Meteorological Office, Pune-411 005) : Study of agrometeorological parameters for the Kharif maize at Anand (Gujarat). Mausam 2002, 53(2), 127-32.

Study was conducted on the behaviour of evaporation, evapotranspiration and potential evapotranspiration in different phenological phases, during the years 1989, 1990 and 1991 for Kharif Maize crop at Anand (Gujarat). It has been noticed that evapotranspiration and potential evapotranspiration attained maximum values in grain phase. In harvesting phase relative evapotranspiration and crop coefficient had lowest values. The seasonal crop coefficient was obtained 0.84. An attempt has been made to develop the regression models to estimate potential and relative evapotranspiration.

3 illus, 2 tables, 4 ref

020506   Suresh R;Rengarajan S (Regional Meteorological Centre, , Chennai-600 006) : Forecasting cyclone movement using TOVS data. Mausam 2002, 53(2), 215-24.

Tracks of three cyclonic storms over Bay of Bengal and one over Arabian Sea during 1998 have been analysed using the TOVS data received at Chennai from NOAA satellites. Midtroposheric warmness between 700 and 400 hPa levels which protrudes about 300 to 700 km ahead of the storm acts as precursor to foreshadow the storm movement and predict the landfall about 6 to 24 hrs in advance. This technique has successfully predicted even the peculiar southward movement of Bay storm (28 November to 7 December, 1996).

8 illus, 11 ref

020505   Subba Rao N;Prakasa Rao J;Jhon Devadas D; Srinivasa Rao K V;Krishna C;Nagamalleswara Rao B (Department of Geology, Andhra University, Visakhapatnam-530 003) : Hydrogeochemistry and groundwater quality in a developing urban environment of a semi-arid region, Guntur, Andhra pradesh. J Geol Soc India 2002, 59(2), 159-66.

Describes the results of hydrogeochemistry and groundwater quality to generate baseline information on groundwater resources in the developing urban area of Guntur, Andhra pradesh. The area falls under a semi-arid type of climate and consists of charnockites and alluvium. Grondwaters are mostly brackish type, having Na⁺: Cl^- facies, that are of meteoric origin. The waters are subjected to evaporation/evapotranspiration process under climatic influence aided by gentle slope, intensively irrigated lands and continued re-use and re-cycling of waters. This process tends to remove ions from the waters for formation of new clay minerals and precipitation of CaCO₃. The soils in the area appear to have the ability to pick up these ionic species during the pre-monsoon season. In the subsequent post-monsoon period, the waters become more saline, which suggests that the ions are leached from soils by the infiltrating recharge waters and are added to the groundwater body. In accordance with the domestic and industrial water quality standards, these groundwaters are not safe. The urban authorities of the area, therefore, should take necessary ameliorative steps to overcome the adverse effects caused by the inferior quality of groundwater.

4 illus, 4 tables, 28 ref

020504   Sriramguru K;Janardhan A S;Basava S; Basavalingu B (Department of Geology, University of Mysore, Manasa Gangotri, Mysore-570 006) : Prismatine and sapphirine bearing assemblages from Rajapalaiyam area, Tamil Nadu: origin and metamorphic history. J Geol Soc India 2002, 59(2), 103-10.

Sapphirine and kornerupine bearing assemblages in Mg-Al-rich pelites have been reported in and around the Kodaikanal hills and in the Kambam valley, forming part of the 550 Ma old Southern Granulite Terrain (SGT). Prismatine and sapphirine are found in a new association with garnet-orthopyroxene-cordierite-spinel-plagioclase-perthite bearing pelitic enclaves in granitic bodies intruding the charnockites at Rajapalaiyam, located on the southern slopes of the Varushanad hills and east of the Kambam valley. Prismatine with boron <62> 0.5 apfu is either associated with orthopyroxene or armoured by cordierite, suggesting its early formation. Association of prismatine with orthopyroxene and quartz is significant. Boron for the formation of prismatine must have come from the sedimentary protoliths, and fixed in the prismatine during fluid activity connected with earlier granulite grade metamorphism. Sapphirine bearing assemblages occur as mm-sized specks in granetiferous granite close to the pelitic bands. This type of sapphirine is different from the general occurrence of sapphirine-orthopyroxene-cordierite forming as a breakdown product of garnet in SGT. Sapphirine bearing assemblages of SGT generally have formed during high grade, granulite facies metamorphism, with peak at 850-1000°C at P of 8.2-8.8 Kbar and with a dominant isothermal decompression path as shown by the assemblages orthopyroxene-cordierite±plagioclase which give T of 650°C at P of 6.5 Kbar. Orthopyroxene-cordierite association after garnet gives T of 900°C at P of 7.5 Kbar in Rajapalaiyam area.

6 illus, 2 tables, 27 ref

020503   Sridharan S;Muthuchami A (Regional Meteorological Centre, , Chennai) : Some salient features of the bay of bengal super cyclonic storm of october 1999. Mausam 2002, 53(2), 237-41.

10 illus, 4 ref

020502   Sohani D;Pande S;Srivastava V S (Centre for P G Research in Chemistry, G T P College, Nandurbar-425 412) : Ground water quality at tribal town Nandurabar (Maharashtra). Indian J Envir Ecoplann 2001, 5(3), 475-9.

Asessment of physico-chemical characteristics of 16 ground water samples collected from the borewells of different colonies of Nandurbar town (Maharashtra) was carried out. Samples were collected before rainy season and after rainy season between Jan - Dec. 2000 and analysed for 15 parameters related to water quality. It was found that some physico-chemical parameters within the permissible limit and some are beyond the permissible limit of drinking water standards. High iron content (0 - 5.80 mg/I) have been selected. The correlation and regression analysis was carried out for selected parameters. Reveals that, ground water of this town is dominated by bicarbonate ion with magnesium and calcium cations. Further, an attempt has been made to identify the source of all pollutants with change in seasons using co-efficient of variation of the parametric ratios.

3 tables, 9 ref

020501   Singh S B;Stephen J;Srinivas Y;Singh U K; Singh K P (NO, National Geophysical Research Institute, Hyderabad-500 007) : An integrated geophysical approach for groundwater prospecting: a case study from Tamil Nadu. J Geol Soc India 2002, 59(2), 147-58.

Delineation of groundwater resources in hard rock terrains is one of the important topics to be treated with a more advanced approach than simple one-dimensional attitude, particularly when looking for deeper water saturated horizons. Introduces an integrated geophysical approach to identify structural features such as fractures, weak zones and intrusive dyke bodies, which can control and host potable groundwater at greater depths. The study is conducted in an area of about 8 km² along east coast of Tamil nadu, which has been identified as a major rainshadow zone. Geophysical measurements were carried out in very closely spaced grids making use of resistivity, magnetic and electromagnetic techniques. The sensitivity of each technique to different rock properties in varying directions has been considered to resolve the problem. A major weak zone running in SW-NE direction is demarcated which is characterised by many intrusive dyke bodies. The conductivity distributions at different depths throw light on many structural features. The varying thickness of weathered rock calculated from the Horizontal Loop Electromagnetic (HLEM) and Deep Resistivity Sounding (DRS) studies for the entire area reflects the extension of weathering associated with dyke emplacements. Goe-electrical sections obtained through DRS studies, concentrated mainly along the weak zone have shown the occurrence of potable groundwater resource controlled by structural features.

7 illus, 23 ref

020500   Singh R P;Jamal A (NO, Central Ground Water Board, 217, Cvil Lines Bareilly-243 001) : Dykes as groundwater loci in parts of Nashik district, Maharashtra. J Geol Soc India 2002, 59(2), 143-6.

Field observations and analyses of the pumping test data of dug wells in parts of Nashik District show that dykes act as potential aquifers when they are jointed/fractured. On the other hand, when they lack primary porosity and permeability and are not jointed / fractured, they act as groundwater barriers. In such a case the upslope of the terrain functions as a good repository, while the downslope remains unproductive. In both the cases, as dykes help to find promising water-bearing formations, they may be referred to as loci of groundwater.

2 illus, 1 table, 3 ref

020499   Singh M;Kharbanda K L;Bhan S C (Meteorological Centre, , Chandigarh) : Study of radio refractive index and wing index associated with onset of monsoon over Chandigarh. Mausam 2002, 53(2), 241-4.

2 illus, 2 tables, 4 ref

020498   Singh A K (Environmental Management Group, Central Mining Research Institute, Barwa Road, Dhanbad-826 001) : Quality assessment of surface and subsurface water of Damodar River Basin. Indian J envir Hlth 2002, 44(1), 41-9.

Hydrogeochemical analyses were carried out on surface and subsurface samples collected from different part of the Damodar river basin. The analytical results show that Calcium and bicarbonate are the dominant cations and anions respectively in surface water, while in subsurface water calcium is replaced by sodium in cationic abundance. The TDS content of subsurface water is two to three times higher than of surface water. The higher TDS of subsurface water may be due to longer residence time, favouring acquisition of solutes through rock weathering. Gibbs variation diagram shows that rock weathering mainly controls chemistry of the Damodar river basin. Quality assessment study of Damodar river basin water shows that with few exceptions, subsurface water is suitable for drinking and domestic uses. Based on SAR, RSC and percent Na the surface water fall within the excellent to good quality class and subsurface water within good to permissible limit and it can be used for irrigation without any hazard. However, the high %Na, RSC and SAR values at a few sites restrict its suitability for irrigation purpose. Ca-Na-HCO₃ is the dominant hydrochemical facies in surface water while Na-Ca-HCO₃ is the common hydrochemical facies in subsurface water.

5 illus, 2 tables, 21 ref

020497   Sehgal R K;Nanda A C (NO, Wadia Institute of Himalayan Geology, Dehra Dun-248 001) : Palaeoenvironment and palaeoecology of the lower and middle Siwalik subgroups of a part of Northwestern Himalaya. J Geol Soc India 2002, 59(6), 517-29.

The faunal assemblages from the red bed successions exposed at Ramnagar (J & K) and Nurpur (H.P) have been used to reconstruct the palaeoenvironment and palaeoecology of the two areas. The two assemblages are of different ages. The succession at Ramnagar is equivalent to the Chinji Formation (Astarcian) of the Lower Siwalik Subgroup, whereas the Nurpur succession represents the Middle Siwalik Subgroup (Turolian). Red mudstones are dominant in both areas and indicates deposition in a meandering fluvial regime with broad flood plains, but in Nurpur, occasional high energy condition also existed, as suggested by the presence of multistoried sandstone bodies. The faunal assemblages of the Ramnagar and Nurpur areas comprise aquatic and semi-aquatic, arboreal and terrestrial communities. The terrestrial community, represented by mammals, is the most dominant in both areas. In the Ramnagar assemblage, suids, tragulids, bovids and giraffids are better represented and point towards a tropical humid environment with prominent swampy conditions. In Nurpur assemblage, besides suids, tragulids and bovids, hipparionines and large giraffids are common. This suggests reduction of tropical rain forests and development of wide and open grasslands separated by tree canopy forests. The habitat characteristics of the various taxa have been discussed to work out the palaeocology of the two areas.

3 illus, 3 tables, 48 ref

020496   Sarin M M (Physical Research Laboratory, , Navrangpura, Ahmedabad-380 009) : Biogeochemistry of Himalayan rivers as an agent of climate change. Curr Sci 2001, 81(11), 1446-50.

Uplift of the Himalaya, intensification of the Asian monsoon and increased erosion from the Himalayan orogen are all intimately coupled and reflected in the transport of weathering products to the ocean by the large rivers, namely the Indus, Ganga, Brahmaputra, Mekong, Chang Jiang and Irrawady. In recent years, several studies have focused on the coupling between continental weathering rates and changes in atmospheric CO₂ budget. Because the atmospheric CO₂ reservoir is realively small and CO₂ gets converted to bicarbonate anion (HCO-₃) and is balanced by dissolved cations from the silicate/carbonate rocks; it is likely that this reservoir is sensitive to changes induced by chemical weathering rates. In such a scenario, increased chemical weathering and associated CO₂ consumption rates in the Himalayan rivers could alter the atmospheric CO₂ levels and hence the global climate. Both oceanic and terrestrial evidence points to a marked, progressive period of intense cooling of global climate over the geologic past. Existing-models of the global CO₂ cycle do not include detailed consideration of such tectonically-driven enhanced chemical weathering. Evaluates the present-day Co₂ consumption rates by chemical weathering processes in the Himalaya, based on newer data, and their implications to long-term climate change.

5 illus, 23 ref

020495   Saha K;Saha S (NO, , 4008 Beechwood Road, West Hyattsville, MD.20782, USA) : African monsoons. 2. Synoptic-scale wave disturbances in the intertropical convergence zone over north Africa. Mausam 2002, 53(2), 197-14.

Discusses several aspects of the origin, structure, development and movement of wave disturbances over the North African tropical zone during the northern summer. Analyzing the cases often actual wave disturbances which later in their life cycles developed into hurricanes over the Atlantic, it finds that though the horizontal and vertical shear of the mean zonal wind associated with the mid-tropospheric easterly jet over Africa satisfies the condition of dynamical instability under certain restrictive boundary conditions, it is the influence of a largeamplitude baroclinic wave in mid-latitude westerlies upon a stationary wave in the mountainous region of the east-central north Africa that appears to trigger the birth of a wave disturbance in the intertropical convergence zone over the Nile valley of Sudan between the Marra and the Ethiopian mountains. Physical processes likely to be important in the formation, development and movement of the disturbances ae pointed out.

12 illus, 1 table, 17 ref

020494   Rohtash Kumar;Ghosh S K;Sangode S J;Thakur V C (NO, Wadia Institute of Himalayan Geology, P O Box 74, Dehra Dun-248 001) : Manifestation of intra-foreland thrusting in the Neogene Himalayan Foreland basin fill. J Geol Soc India 2002, 59(6), 547-60.

Neogene basin fills of the Middle and Upper Siwalik Subgroup in the central sector of Indian foreland basin record changes in fluvial architecture, dipersal pattern and provenance in response to deformation and uplift of the frontal Himalaya. The 2.4 km thick Neogene Siwalik succession in the Subathu sub-basin exposed in the vicinity of Nahan Thrust (intra-foreland thrust of IFT) shows fine-to medium-grained grey sandstones of multi-storey, sheet type deposited by transverse trunk rivers. A significant change in sediment dispersal from SE to SW is observed at 5.5 Ma for grey sandstone and to SE around 4.8 Ma for buff sandstone. Both the sandstones are lithicarentes with dominance of sedimentary rock fragments in the buff sandstone. The filling pattern and occurrence of soft-sediment deformation structures, particularly between 4.8 and 2.6 Ma, indicate tectonically controlled re-organisation of drainage pattern and gradual change in source area from Lesser Himalayan to Sub-Himalayan region. These changes after 4.8 Ma are mainly governed by intra-foreland thrust activity, which resulted in partitioning of foreland basin. Further, a significant overlap of Tertiary clast-bearing conglomerate with that of pre-Tertiary clast-bearing conglomerate at around 1.77 Ma shows a major reactivation along IFT.

9 illus, 60 ref

020493   Rastogi R G (Physical Research Laboratory, , Navrangpura, Ahmedabad-380 009) : New feature of low latitude geomagnetic storms. Curr Sci 2001, 81(11), 1462-6.

It has been shown that the geomagnetic storms during their main phase cause significant decrease in the geomagnetic H field at low latitudes, in addition to that expected due to the disturbance ring current. This additional westward equatorial ionosphere current at low latitude coincides in time with the period of high interplanetary magnetic B field, its southward direction and large auroral electrojet current. It is suggested that this auroral electric field associated with high latitude field-aligned currents and is transmitted to low latitudes by the earth and ionosphere transmission line processes.

4 illus, 1 table, 25 ref

020492   Rameshwar Rao D;Rai H (NO, Wadia Institute of Gimalayan Geology, 33 General Mahadeo Singh Road, Dehradun-248 001) : RB-Sr isotopic studies of Huga gneiss and Polokongka La granite from Tso-Morari region of Ladakh, J&K, India. Curr Sci 2002, 82(9), 1077-9.

^ssc2 illus, 1 table, 10 ref

020491   Ramesh R (Physical Research Laboratory, , Navrangpura, Ahmedabad-380 009) : High resolution holocene monsoon records from different proxies: an assessment of their consistency. Curr Sci 2001, 81(11), 1432-6.

Available high resolution quantitative monsoon reconstructions for the Holocene period in the Indian region are compared to assess for consistency among the proxy records. There is a good concordance among three different monsoon proxies from western India: (a) Pollen-based reconstruction of annual rainfall in Rajasthan from a sediment core in lake Lunkaransar, (b) stable carbon isotope variations in organic carbon from another core from the same lake, and (c) stable oxygen isotopic variations in surface-dwelling foraminifera from a seiment core in the coastal eastern Arabian Sea. While this is reassuring, the degree of concordance diminishes when records from widely separated sites in the Indian region are compared. Possible causes for this inconsistency are discussed, perhaps the most important among them being the large spatial variations in monsoon rainfall over the Indian region, apparent in modern instrumental records. There is a need to assess the temporal variance of this geographical variability before multiproxy quantitative monsoon rainfall reconstructions can be integrated as a single time series. Such an effort can serve to test and improve Palaeoclimate/palaeomonsoon models.

4 illus, 23 ref

020490   Rajeevan M (India Meteorological Detpartment, , Pune-411 005) : Prediction of Indian summer monsoon: status, problems and prospects. Curr Sci 2001, 81(11), 1451-7.

Since 1988, the India Meteorological Department has been issuing forecasts based on 16-parameter power regression and parametric models. All these forecasts are proved to be reasonably correct. However, in some years, forecast error was larger than the model error of ± 4%. In 2000, four new promising predictors were introduced in the operational models. Using an empirical model with 100 years of data (1901-2000), it has been show that Indian summer monsoon predictability exhibits epochal variations. During the recent years the model is showing poor forecast skill due to weakened coupling between the boundary forcing and Indian monsoon. In spite of serious efforts by the modelling groups, there are still problems in the dynamical predictios of Indian monsoon. Prediction of Indian monsoon variability is found to be sensitive to the initial conditions, suggesting that chaotic internal dynamics may ultimately limit the predictability of Indian summer monsoon.

5 illus, 3 tbales, 27 ref

020489   Prasad A V K;Beg M J;Chaturvedi A (Geological Survey of India, Anarctica Division, Faridabad-121 001) : Petrography of Lamprophyre dikes from nunataks South of Schirmacher, Central dronning maud land, East Antarctica. Curr Sci 2001, 81(11), 1477-8.

A number of lamprophyre dikes intrude the ortho-and pelitic gneisses of Central Dronning Maud Land (cDML) in East Antarctica. In the four nunataks - Baalsrudfjellet, Starheimtind, Sonstebynuten and Pevikhornet, athe lamprophyres exhibit three distinct mineral assemblages, biotite-clinopyroxene, biotite-clinopyroxene-olivine and biotite-clinopyroxene-horn-blende. Ocelli are invariably feldspathic in composition (Type 2). Based on the mineral assemblage and composition of the ocelli, the dikes have been grouped under calc-alkaline lamprophyre clan.

5 illus, 6 ref

020488   Pavlish L A;Wilson G C;Nijagunappa R (Iso Trace Laboratory, University of Toronto, Toronto, Ontario, Canada M5S 1A7) : Toranagallu mound: provenance of unusual glassy materials. J Geol Soc India 2002, 59(6), 503-15.

Slag-like material from a mound of uncertain origin near the town of Toranagallu in the Bellary District of Karnataka, was analysed with the purpose of determining its origin. The material exemplifies `ash mounds' of Neolithic age, which are abundant in the Deccan plateau and surrounding areas of Peninsular India. The material is porous and glassy, with abundant diopside crystallities in a rather homogeneous glassy matrix. Bulk analyses by instrumental neutron activation analysis (INAA), XRF and ICP-based methods, including ICPMS of REE, plus in situ electron-probe microanalysis (EPM) of the glass and crystallites provide chemical and mineralogical constraints on possible origins. The analytical results suggest that the sample may represent residue from a glass-making operation. This result defines one use of the mound, but leaves open the possibility that a range of other activities may have contributed to the mounds development over a protracted time span.

5 illus, 3 tables, 53 ref

020487   Pal T;Dutta Gupta T;Das Gupta S C (NO, , GSI, GSI Complex, Karunamoyee, DK Block, Salt Lake, Kolkata-700 091) : Vitric tuff from archipelago group (Mio-Pliocene), South Andaman. J Geol Soc India 2002, 59(2), 111-14.

Vitric tuff is being reported from Archipelago Group of South Andaman. The tuff is composed of delicately shaped glass shades with vairable amount of microlites and broken phenocrysts of quartz, plagioclase and mica. Major oxide analyses show dacitic composition of the tuff. Petrographic and XRD studies show that the glass is altered to clinoptilolite and analcime. The sedimentary structures in tuff beds suggest these as products of ash turbidite.

3 illus, 1 table, 11 ref

020486   Nath T T;Yadagiri P;Moitra A K (NO, Geological Survey of India, Southern Region, Hyderabad-500 068) : First record of armoured dinosaur from the lower Jurassic Kota Formation, Pranhita-Godavari valley, Andhra Pradesh. J Geol Soc India 2002, 59(6), 575-7.

^ssc1 illus, 9 ref

020485   Natarajan K;Narayanan K;Kumaresan V (NO, University of Madras, Guindy Campus, Chennai-600 025) : Basidiocarp production in Agaricus heterocystis Heinem, and Gooss. in nutrient agar media. Curr Sci 2002, 82(9), 1084-5.

^ssc2 illus, 1 table, 8 ref

020484   Nandankar P K;Srinivasan G;Mujawar Z G (Regional Meteorological Centre, , Mumbai) : Wing and wave regime over the Bombay high area under the influence of cyclonic storms. Mausam 2002, 53(2), 187-96.

Temporal distributions of wind and wave over Bombay High Area (BHA) during cyclone period have been studied. Ten years' (1990-99) data of BHA during cyclone period have been used. It is found that under the influence of cyclonic storms strong southwesterly winds prevail over the BHA in pre-monsoon and weaker east to southeasterly winds during post-monsoon. Southwesterly wave with heights exceeding 20 feet are encountered in BHA during pre-monsoon and south easterlies with wave height reaching up to 12 feet in post monsoon. Analysis of situations with different storm locations also yielded similar results. Relationships between wind speeds and wave height as well as the distance of the storm centre over BHA have been established.

8 illus, 1 table, 10 ref

020483   Misra K S (NO, Geological Survey of India, Alandi Road, Phulenagar, Pune-411 006) : Arterial system of lava tubes and channels within deccan volcanics of Western India. J Geol Soc India 2002, 59(2), 115-24.

Interpretation of remotely sensed and field data has brought out an integrated arterial system comprising lava tubes and channels, through which molten basaltic lava seems to have flowed to long distances in the Deccan Trap of western Maharashtra and southern Madhya Pradesh. Remnants of lava tubes and channels are identified at more than two hundred places in the study area, covering 120,000 km². The lava tubes and channels are demarcated by their unique sinuous shapes and positive relief based on remotely sensed data. In the field, they are recognized by their tubular outline, which is invariably composed of reddened fragmentary volcanic material, encasing dark greyish basalt having unique textures. The diameter of lava tubes and width of channels are much larger within the study area than those reported from the Quaternary and Recent volcanics in different parts of the world which suggests very high effusive rates during Deccan volcanism. Mostly these tubular structures are filled by solidified lava suggesting that flow gradients were very low and therefore withdrawal of molten lavas has not taken place. Mostly they are confined to the compound flow sequences and are rarely seen within the simple flows. These remnants are predominantly exposed between 200 m and 800 m elevations and are located at high elevations in the western part of the study area and at successively lower levels in the easterly direction. This indicates that block faulting controlled by en echelon basement faults, was largely responsible for down faulting of successive blocks in the easterly direction.

6 illus, 14 ref

020482   Manglik A;Singh R N (NO, National Geophysical Reseach Institute, Uppal Road, Hyderabad-500 007) : Thermomechanical structure of the central Indian shield: constraints from deep crustal seismicity. Curr Sci 2002, 82(9), 1151-7.

Intraplate seismicity in the Indian shield is confined to the upper 10-15 km except for the Jabalpur and Satpura events which occurred at a depth of 35-40 km in the region bounded by the Narmada-Son and Tapti lineaments, two major palaeo-rift-related tectonic features in the central Indian shield. Interestingly, high surface heat flow of 70-100 mW/m² has been suggested for the above region. Rheological models of continental crust in such a high heat flow regime do not support occurrence of deep crustal seismicity. Range of rheological models for the region for different values of thermal parameters have been analysed these have been computed in the light of deep crustal seismicity. The study suggests that mantle-derived heat flow should be significantly low for the occurrence of deep crustal events in the above region and the excess surface heat flow could be a manifestation of fluid advection in the uppermost part of the crust, as is evident from the presence of many hot springs.

3 illus, 1 table, 38 ref

020481   Mall R K;Gupta B R D (Central Ground Water Board, Ministry of Water Resources, , New Delhi) : Comparison of evapotranspiration models. Mausam 2002, 53(2), 119-26.

Actual evapotranspiration of wheat crop during different year from 1978-79 to 1992-93 was measured daily in Varanasi. Uttar Pradesh using lysimeter. In this study three evapotranspiration computing models namely Doorenbos and Pruitt, Thornthwaite and Soil Plant Atmosphere Water (SPAW) have been used. Comparisons of these three methods show that the SPAW model is better than the other two methods for evapotraspiration estimation. MBE (Mean-Bias-Error), RMSE (Root Mean Square Error) and t-statistic have also been obtained for better evaluations of a model performance.

2 illus, 1 table, 28 ref

020480   Madhavaraju J;Ramasamy S (Department of Geology, School of Earth and Atmospheric Sciences, University of Madras, Guindy Campus, Chennai-600 025) : Petrograpky and major element geochemistry of late Maastrichtian-early palaeocene sediments of Tiruchirapalli, Tamil Nadu - palaeoweathering and provenance implications. J Geol Soc India 2002, 59(2), 133-42.

Petrography and geochemical studies of the Late Maastrichtian-Early Palaeocene sediments of Kallamedu and Niniyur Formations of Tiruchirapalli have brought out significant results on palaeoweathering and source area characteristics. In the bivariate plot of SiO₂₂O₃, +K₂O+Na₂O, all the clastic samples fall in the arid field indicating that the arid climatic condition prevailed in the source region during the deposition of these sediments. In the Al₂O₃ vs Na₂O plot, the clastic samples fall between low grade Archaean shale and post-Archaean shale suggesting that the detrital components have been derived from low to moderately weathered terrain. The Chemical Index of Alteration of clastic sediments range 40 to 69 with lower values for sandstones (40 to 57) than for silty shale and shale (61 to 69) and this indicates that the source rocks have undergone low to moderate chemical weathering. In QFL diagram, most of the sandstones fall in the field of cratonic interior basin which indicate that these sediments were deposited in the stable craton. SiO₂/Al₂O₃ ratios are high observed for sandstone, silty shale and shale, with a range strating from 3.15 to 8.75. The higher ratios of SiO₂/Al₂O₂ mmin clastic sediments indicate a largely felsic rock provenance. Major element data indicate an overall taphrogeosynclinal continental rift-related depositional basin.

8 illus, 2 tables, 41 ref

020479   Lande V W (NO, National Environmental Engineering Research Institute, Nehru Marg, Nagpur-440 020) : Foraminifera population in the coastal water of east coast. Acta Ecol 2001, 23(1), 34-8.

Planktonic Foraminifera is enumerated in the benthos samples of East Coast off Vishakhapatnam. Tiny protozoa is present inside the Calcareous shells. The number of genus identified belongs to Globigerina sp, Globorotalia sp and Hastigerina sp in Sediments. Geological scale of aging oil and gas exploration area and fossil rock strata indicating the presence of Foraminifera population.

2 illus, 7 ref

020478   Lakshiminarayana G (NO, , Sandhyagiri Apartments, F-304, Kalyannagar, Gaddiannaram, yderabad-500 060) : Sedimentary facies and stratigraphic significance of Cumbum and Barirenkonda type sections of Nallamalai fold belt, Cuddapah basin, Andhra Pradesh. J Geol Soc India 2002, 59(2), 167-77.

Sedimentary facies in the Cumbum and the Bairenkonda type sections include banded slate, graded rhythmite, quartzite and dolomite (Cumbum Formation), quartzite-slate, massive quartzite, parallel stratified quartzite and medium to thick bedded quartzite (Bairenkonda Formation). The quartzite-slate facies marks the gradational contact between the Cumbum and the Bairenkonda Formations. Stratigraphic disposition of sedimentary facies between these two type of sections in identical and correlatable. These sediments are deformed into NNE-SSW trending tight to open folds and NW-SE to E-W trending cross folds. It is now indicated that the Cumbum Formation is stratigraphically older than the Bairenkonda Formation and the resultant succession is at variance to the hitherto held stratigraphically framework. The arigillite-dominated Cumbum sedimentary facies indicates deep-water depositional setting, whereas the arenite - dominated Bairenkonda facies represents shallow water environment, thereby pointing to the shallowing up to the basin during Nallamalai sedimentation.

9 illus, 2 tables, 11 ref

020477   Kulkarni B D;Munot A A (NO, Indian Institute of Tropical Meteorology, Pune) : Some aspects of inter-annual variability of rainfall over Godavari river basin. Mausam 2002, 53(2), 233-6.

2 illus, 1 table, 11 ref