003256   Bhatnagar A K;Rajesh Rao P;Kalyanasundaram S; Thampi S B;Suresh R;Gupta P (NO, , ) : Doppler radar - a detecting tool and measuring instrument in meteorology.. Curr Sci 2003, 85(3), 256-64.

India Meteorological Department has entered into a new era in exploring the atmosphere with the induction of state-of-art Doppler weather radar technology in its cyclone detection radar network. This article describes the salient features of the Doppler weather radar installed at Chennai. Use of Doppler technique combined with digital technology makes it possible to measure directly the wind component along the axis of the radial beam along with range-finding, in addition to a large number of derived products which become available in real time. A few typical examples of multifarious products available from this radar are presented. The scope for its utility in operational weather forecasting, particularly in the fields of cyclone warning and aviation has been highlighted.

7 illus, 7 ref

003255   Bhadram C V V (NO, Meteorological Centre, Airport, Hyderabad-500 016) : Synoptic study of active and weak southwest monsoon over Andhra Pradesh. Mausam 2003, 54(2), 385-92.

An attempt has been made in this study to identify the synoptic systems that cause active or vigorous monsoon conditions over the three meteorological sub-divisions of Andhra Pradesh using the data for the years 1986 to 2000. Despite significant decrease in the frequency of formation of monsoon depressions in recent years, monsoon performance is noticed to be very good. Monsoon lows and upper air cyclonic-circulations (cycirs) found to be the chief synoptic systems which activate the monsoon over the state. Typical cases of these synoptic situations are discussed.

4 illus, 3 tables, 4 ref

003254   Behera P (Dep of Geology, Utkal University, Bhubneshwar-751 004) : Heavy minerals in beach sands of Gopalpur and Paradeep along Orissa coastline, east coast of India. Indian J Mar Sci 2003, 32(2), 172-4.

Selective sand samples were collected from Gopalpur and Paradeep beaches and studied for their heavy minerals assemblage. Beachsands of both the areas contain heavy minerals like sillimanite, ilmenite, garnet, pyroxene, rutile, sphene, biotite, hornblende, zircon and monazite. At Gopalpur, the percentage of concentration of sillimanite is the highest followed by limonite, garnet, pyroxene, rutile, sphene, biotite, hornblende, zircon and monazite. At Paradeep, almost similar trend was observed with some exceptions, i.e. concentration of pyroxene and biotite is more here. The mineral sphene was absent at Paradeep, whereas tourmaline was negligible at Gopalpur. Higher grade percentage of heavies of Gopalpur is linked with many favourable factors and is being mined by IREL whereas low grade percentage at Paradeep discourages mining.

^ssc1 illus, 1 table, 10 ref

003253   Basu B K (NO, , NCMRWF, Lodi Road, New Delhi-110003) : Verification of model predicted precipitation over India during the summer monsoon of 1997. Mausam 2003, 54(2), 359-76.

For the monsoon season of 1997 the precipitation observation from 1333 rain gauge stations are used to form spatial averages for 135 grid points of the NCMRWF forecast model covering the whole of India. These spatial averages are compared with the model forecasts of precipitation by computing the mean error, mean absolute error, root mean square error and correlation coefficient. The skill of forecast is also computed by discretizing the precipitation amounts in to standard categories. The seasonal accumulated precipitation and its spatial distribution are well reproduced in the model predictions up to 4-days in advance. The mean error in prediction shows spread of precipitation across the Western Ghat hills as the barrier effect is under estimated in the model due to poor horizontal resolution. The correlation coefficient shows good inphase relationship between the predicted and observed precipitation especially over areas of very large seasonal precipitation. Over a small area this coefficient has values higher than 0.6. The model has kill for categories of precipitation with class mark up to 1.0 inch and prediction lead-time up to 2 day.

17 illus, 3 tables, 15 ref

003252   Banerjee R;Ray D (Geological Oceanography Division, National Institute of Oceanography, Dona Paula, Goa-403 004) : Metallogenesis along the Indian ocean ridge system. Curr Sci 2003, 85(3), 321-7.

Twenty years after the discovery of the sea-floor hot springs, vast streches of the global mid-ocean ridge system still remain unexplored for locating hydrothermal vents. In comparison to the mid-oceanic ridge systems of the Pacific and the Atlantic, so far the Indian Ocean Ridge system (IORS) drew less attention from the world researchers towards finding out hydrothermal deposits. But recently several investigations took place in this direction by investigators of about half a dozen countries including India. Among these studies majority were concentrated around the Central Indian Ridge and the Southwest Indian Ridge areas, while a few observations were made around the rest of the areas in the IORS. The findings of these studies are discussed.

1 illus, 1 table, 33 ref

003251   Banerjee R;Iyer S D (Geological Oceanography Division, National Institute of Oceanography, Dona Paula, Goa-403 004) : Genetic aspects of basalts from the Carlsberg ridge. Curr Sci 2003, 85(3), 299-305.

The origin of the basaltic rocks with heterogeneous composition from the Carlsberg Ridge (CR) is of interest for more than one reason. In comparision to other Mid-Oceanic Ridge (MOR) systems sufficient data on petrochemical and petrographical aspects of the CR rocks are sparse. The bulk chemical, mineral chemical and ore mineralization aspects of the dredged basalts from a segment of the CR (at 3°37'N, 64°57'E) are synthesized to indicate the influence of fractional crystallization coupled with magma mixing on their genesis.

6 illus, 2 tables, 51 ref

003250    (NO, , ) : Inter annual and intra decedal behaviour of monsoon rainfall over Jalpaiguri. Mausam 2003, 54(2), 539-60.

illus, tables, ref

003249    (NO, , ) : Jurassic ostracode fauna of Bela Island, Rann of Kachchh, Gujarat. Curr Sci 2003, 85(3), 249.

2 illus, 1 table, 8 ref

002420   Vinod Kumar (NO, Meteorological Office, Mumbai-400 099) : Maximum and minimum temperatures as predictor elements of south-west monsoon rainfall over Gaya: a statistical approach. Mausam 2003, 54(4), 935-7.

^ssc3 tables, 3 ref

002419   Veerabuthiran S;Satyanarayana M (Space Physics Laboratory, , Trivandrum-695 022) : Lidar observations on atmospheric dust transported from south-west Asia to India west coast region: a case study of colour rain event occurred during July 20-01. Indian J Radio Space Phys 2003, 32(3), 158-65.

A dust strom, which originated in the dust bowl of Arabia, Iran, Afghanistan, Pakistan and north-western of parts of India during the month of July 2001, had lifted large quantities of dust into the atmosphere and got transported over long distances. The region of the west coast of India had experienced the interesting phenomenon of "color rain" due to this dust loading. A typical dust layer had been detected in the lower troposphee using a lidar system located at Trivandrum (8° 33'N, 77°E) during the night of 24 July 2001 prior to the occurrence of colour rain. The lidar measurements indicated that the dust cloud was present in the 4-5 km altitude range with thickness of a few hundred metres. Air back trajectory computed by the HYSPLIT-4 model using NCEP wind data at the 4500 m level clearly indicated that the dust probably had its origin in the south-west Asia, nine days before the event.

5 illus, 31 ref

002418   Tinmaker M I R;Nath A;Kandalgaonkar S S (NO, Indian Institute of Tropical Meteorology, Pune) : Probabilistic estimation of thunderstorm activity at a tropical inland station, Pune during post-monsoon season using Markov chain models. Mausam 2003, 54(4), 932-4.

^ssc3 tables, 11 ref

002417   Soni V K;Kannan P S (NO, Meteorological Office, Pune-411 005) : Temporal variations and the effect of volcanic eruptions on atmospheric turbidity over India. Mausam 2003, 54(4), 881-90.

Atmospheric Turbidity data collected over a period of about 23 years (1975-97) at Indian `Global Atmospheric Watch' stations have been analysed to determine the major causes of time variation. The most extreme perturbations have been associated with significant volcanic eruptions of El-Chichon, Mexico (17°N, 146°E) in April 1982 and Mt. Pinatubo, Philippines (15°N, 120°E) in June, 1991. The increase in atmospheric turbidity values following these eruptions was discernible for 1.5 - 2 years after the eruption. Annual mean values of the turbidity coefficients computed for the two consecutive decades, 1976-85 and 1986-95, show a general increase of turbidity during the later epoch at all stations except Kodaikanal. Analysis of long-term monthly means shows the seasonal variations and influence of monsoon over turbidity coefficients. A considerable shift of atmospheric turbidity values from the lower band values (0.0-0.1) to higher band (0.1-0.2) also witnessed from the percentage frequency analysis.

5 illus, 2 tables, 21 ref

002416   Sasi Kumar V;Sampath S;Vinayak P V S S K (Atmospheric Science Div, Centre for Earth Science Studies, , Thiruvananthapuram-695 031) : Drop size distribution of rainfall of different intensities. Indian J Radio Space Phys 2003, 32(4), 217-20.

Drop size distribution was measured at Thiruvananthapuram, Kerala State, India, during April, June and July 2001 using a Joss-Waldvogel type disdrometer. The instrument gives the number of drops in 20 size classes ranging from 0.3 mm to <62> 5 mm. Each month's data were sorted, based on rainfall intensity, into periods of rainfall intensity <60> 1 mm/hr, 1-3 mm/ha, 3-10 mm/hr, 10-30 mm/hr and <62> 30 mm/hr. The average number of drops in each size class was computed for each set of data. Exponential and Γ distribution functions were then fitted to each data set. The results showed that, in June and July, the data approximated an exponential distribution for low rainfall intensities, but became closer to the Γ distribution at higher intensities. However, in April all data fitted the Γ distribution, irrespective of rainfall intensity.

3 illus, 2 tables, 6 ref

002415   Sankaran A V (NO, , No. 10, P and T Colony, I Cross, II Block, RT Nagar, Bangalolre-560 032) : The supercontinent medley: recent views. Curr Sci 2003, 85(8), 1121-4.

^ssc1 illus, 36 ref

002414   Roy Bhowmik S K (NO, India Meteorological Department, New Delhi-110 003) : Evaluation of dynamical and thermal anomalies associated with the summer monsoon of 1997 and 1999. Mausam 2003, 54(4), 811-18.

The year 1997 was characterized by rapid development of a strong EI Nino event and during 1999, a La Nina episode prevailed. The response of all India monsoon rainfall to these events in 1997 (above normal rainfall; <62>100%) and 1999 (below normal rainfall: <60>100%) was of unusual nature. The reasons for this have been investigated in terms of planetary scale dynamical and thermal anomaly indices. The major findings of this study are: The early onset of south west monsoon in 1999 was associated with the stronger positive vertical shear of zonal anomaly over the north Indian Ocean, Development of an active inverse Hadley circulation over Indian longitide appears to play an important role to reactivate monsoon during August and September in 1997, Positive anomalies of tropospheric temperature occupied larger area over the Tibetan Plateau in May 1999, The geopotential height anomaly at 200 hPa over the Tibetan Plateau during the month of May in 1999, in the year of early onset, was considerably higher compared to 1997 and The dominance of negative anomalies of mean sea level pressure during May in 1999 over Indian region reflected the La Nina influence.

6 illus, 11 ref

002413   Rao M V M S;Prasanna Lakshmi K J (NO, National Geophysical Research Institute, Hyderabad-500 007) : Shear-wave propagation in rocks and other lossy media: an experimental study. Curr Sci 2003, 85(8), 1221-5.

Ultrasonic shear-wave propagation study have been carried out for the measurments of velocity and attenuation in some rocks, concrete and synthetic materials at room condtions. It has been found that `pulse broadening', which occurs due to attenuation, can be measured quite accurately while carrying out shear-wave velocity measurements in them. The pulse brodening data could be used to determine the quality factor from which the shear-wave attenuation is computed using the standard relationships between velocity, attenuation and quality factor. The measurment technique is briefly described and the results obtained are presented adn discussed.

3 illus, 1 table, 21 ref

002412   Peshin S K;Sharma J K;Rajesh Rao P;Srivastav S K (NO, India Meteorological Department, New Delhi-110 003) : Changes in surface ozone amount and its diurnal and seasonal patterns, from 1990-95 to 1996-2000, measured at New Delhi (28°N). Mausam 2003, 54(4), 947-51.

5 illus, 12 ref

002411   Mukhopadhyay P;Sanjay J;Singh S S (NO, Indian Institute of Tropical Meteorology, Pune-411 008) : Objective forecast of thundery nonthundery days using conventional indices over three northeast Indian stations. Mausam 2003, 54(4), 867-80.

The preconvective atmosphere of the four months (March, April, May and June) for the year 1980-84 have been studied using the Radiosonde data (RS/RW) of the three stations of northeast India namely Guwahati, Dibrugarh and Agartala. The objective is to identify a suitable index for these stations with a prescribed threshold value that can be used as the predictor forecasting thundery/nonthundery days. Total eleven indices are considered in this study. The thermodynamic and kinematic parameters required for calculation of the indices are derived from the RS/RW data of 0000 and 1200 UTC and taking three stations together. Probability distribution curves are plotted to make a qualitative comparison on the ability of the indices to differentiate the thundery and nonthundery days. Mean and standard deviations are calculated and these are used to apply Z-statistics. The indices that have shown Z values at 90% or more significant level are considered for further analysis and rest are rejected. Threshold values of the selected indices are assigned by an iterative process where the mean of value of the index is used as the first guess and skill scores are calculated. Next the first guess value is changed and the skills are recalculated. The process is continued till the best score is attained for each selected index. The threshold values of these indices are used to predict the thundery and nonthundery days of the verification year 1985. It is found that HI has the best skill in forecasting thundery/nonthundery days at 0000 and 1200 UTC for Guwahati, Dibrugarh and Agartala stations.

2 illus, 11 tables, 31 ref

002410   Mittal A K;Dwivedi S;Pandey A C (Megh Nad Saha Centre of Space Studies, Institute of interdisciplinary Studies, University of Allahabad, Allahabad-211 002) : Study of the forced lorenz model of relevance to monsoon predictability. Indian J Radio Space Phys 2003, 32(4), 209-16.

The forced Lorenz model introduced as a paradigmatic model for monsoon prediction is exsplored in greater detail. In particular, a study is made of the bifurcation structure of the forced Lorenz model as the forcing is varied. Shift in the probability distribution function between the two branches of the Lorenz attractor as a function of the forcing is also studied.

7 illus, 9 ref

002409   Mathur K N;Goyal R S;Gupta D (NO, Geological Survey of India, NRO, Aliganj, Lucknow) : Integration of geological, geophysical and geochemical studies to identify new potential target areas for Lead-Zinc & Copper mineralisation in covered terrains of Rajpura-Dariba group, with special emphasis to Bethumbi-Bhupalsagar area, Southern Rajasthan. J Geophys 2003, 24(1), 3-24.

The integrated studies have revealed that before faulting the two belts were contigous and Dariba-Rajpura of Belt-I was in contact with Chhatrikhera of Belt-2, hence mineralisation similar to that of Dariba-Rajpura is also expected at Chhatrikhera-Jashma. this thesis is further supplemented by detailed geological, structural, airborne and surface geophysics, geochemistry and aerial photography data. The study is a successful case of integration of all the branches of earth sciences resulting into delineation of new potential target areas for further detailed exploration by drilling in the covered terrain.

11 illus, 19 ref

002408   Mathew B;Hareesh Kumar P V;Rao R R (NO, Naval Physical Oceanographic Laboratory, Cochin) : Mixed layer variability at selected locations in the Arabian Sea during pre and summer monsoon seasons: observations and simulations. Mausam 2003, 54(4), 917-28.

Observed short term (few days to few weeks) variability of mixed layer depth (MLD) temperature (MLT) at selected locations in the Arabian Sea during pre and summer monsoon seasons is discussed. In the Arabian Sea, pre monsoon season is generally characterized by fair weather conditions with occasional thunder squalls. In the eastern Arabian Sea, SST is above 30°C, which assumed to be the part of the Indian Ocean warm pool, and is characterized by the diurnal range of about 1.5°C. During the monsoon season, maximum cooling (<62>1°C) and deepening (5075 m) of the mixed layer is noticed in the central Arabian Sea during the onset phase. On the contrary, the mixed layer shoals in the coastal zones due to upwelling. Miller's one dimensional mixed layer model is used to simulate the observed mixed layer variability. The model simulated MLT and MLD variations reasonably well on a synoptic scale. Whenever advective process (horizontal and vertical) and large amplitude waves dominate, significant departures are noticed between the observed and simulated values.

6 illus, 1 table, 27 ref

002407   Manohar G K;Kesarkar A P (Space Sciences Dep, University of Pune, Pune-411 007) : Climatology of thunderstorm activity over the Indian region: a study of east-west contrast. Mausam 2003, 54(4), 819-28.

Based on the latest data (I.M.D., 1999) of monthly number of station thunderstorm days (Thn) and mean maximum surface air temperatures (T_max) of 276 Indian stations, an important and a long pending issue of east-west contrast in the frequencies of occurrence of thunderstorms over India is resolved in substantial details in this study. On the premise of nearly equal land areas, and density of the station network, and location of ITCZ; India is divided in two regions: Eastern Region (ER) and Western Region WR) across the 79°E longitude line over India. Results pertaining to the constrasting features of Thn over ER and WR are presented. The analysis showed that the annual total Thn over the ER are 4763, and over the WR are 3194 and the prominent difference in Thn is associated with monsoon season months over the ER and WR. The temperature sensitivity of occurrence of Thn showed that thunderstorms respond exponentially to modest increment in T_max on the semi-annual and annual time-scales in both the regions but with clear contrast in their sensitivity over ER. This result is in good agreement with the results cited in many studies, where relationship between global tropical surface air temperatures and GEC parameters are investigated. The analysis suggests that the hot and humid extensive land region of the ITCZ of the ER is more suitable and responsible for the development of thunderstorms. Further, results showing higher values of CAPE and moisture field over the ER are discussed to explain the E-W pronounced contrast in the thunderstorm activity. It is believed that the results presented in this study will be useful.

3 illus, 2 tables, 22 ref

002406   Mahender Singh;Ram Singh;Ram Niwas;Sahrawat K D (Agricultural Meteorology Dep, CCS, HAU, Hisar-125 004) : Study on south-west monsoon rainfall characteristics in arid zone of Haryana. Mausam 2003, 54(4), 837-42.

The daily rainfall data of arid zone for a period of 50 years (1946-95) at three locations, Hisar, Bhiwani and Sirsa were analyzed to find out characteristics of south-west monsoon. Mean onset date was observed 4 July at Hisar and Bhiwani with standard deviation of 7 to 9 days respectively, whereas 7 July at Sirsa with standard deviation of 9 days. The onset date of monsoon was inversely related to amount of rainfall at all stations under study. The mean withdrawal dates of south-west monsoon were 15 September at Hisar and Bhiwani and 11 September for Sirsa with standard deviation of 9 days at all three locations. The withdrawal dates also showed inverse and significant correlation with rainfall amount. The mean number of rainy days at Hisar, Bhiwani and Sirsa were 18, 17 and 13 with standard deviation of 5, 6 and 6 days, respectively.

3 illus, 2 tables, 6 ref

002405   Lo Seen D (NO, French Institute of Pondicherry, P.B No. 33 Saint Louis Street, Pondicherry-605 001) : Geographical information system and remote sensing for monitoring the environment. Trop Ecol 2003, 44(1), 113-19.

An overview of the possibilities offered when applying Geographical Information Systems (GIS) and Remote Sensing (RS) to environmental monitoring is given, based on examples taken from an ongoing project entitled `Assessment of mangrove degradation and resilience in the Indian subcontinent: the cases of Godavari estuary and southwest Sri Lanka'.

1 illus, 10 ref

002404   Laskar S K;Bhattacharyya A K;Choudhury P (NO, Tezpur University, Napaam-784 028) : Identification and depth-determination of subsurface magnetic causatives in Lanka-Kaki area of Kopili valley, Assam. J Geophys 2003, 24(1), 45-52.

A vertical component magnetic profile extending from Shillong massif to Mikir hills at northwest of Lanka-Kaki line in Kopili Valley is analysed for identification and depth determination of subsurface magnetic causatives lying across it. The analysis reveals that a balastic trap lies concealed in the area. The maximum depth to the basement is about 3.25 km over a span of about 4 km and it is covered by the trap extending over a span of about 10 km at an average depth of about 1.75km in middle of the basin.

4 illus, 4 tables, 10 ref

002403   Lakshminarayanan R;Rajamohan R (NO, Meteorological Centre, Thiruvananthapuram) : Study of unusually heavy to very heavy rainfall over Kerala in October 1999. Mausam 2003, 54(4), 861-6.

Kerala received heavy to very rainfall in October 1999 being a record rainfall of 54.6 cm of the twentieth century for the month of October. A few stations in central Kerala like Punalur, Alappuzha, Kottayam, Konni, Aryankavu, Chertala, Thodupuzha and Mannarghat reported record October month rainfall of the twentieth century. Synoptic features responsible for these heavy rains have been examined. It was found that favourable position of the east-west trough/shear line running across latitude 10° North in the lower and middle troposphere and the strengthening of westerly winds over Lakshadweep and south Kerala in association with systems moving across north Andaman Sea and east central Bay are the prime causes leading to heavy to very heavy rainfall in October 1999 over Kerala for about 20 days in October.

6 illus, 4 ref

002402   Kulandaivelu E;Dang S P (NO, Regional Meteorological Office, Chennai) : Case study of katabatic winds over Schirmacher Oasis, east Antarctica. Mausam 2003, 54(4), 843-50.

Katabatic winds are a regular feature during night and early morning hours over valleys and low lying areas adjacent to high terrains. In Antarctica, the mass of the earth in the form of plateau is covered with full of ice and has a downslope from the South Pole everyside upto the coast. Due to cooling of air near the ground as well as due to pressure gradient, the coastal belt often experiences strong winds blowing down the slope of the plateau. In this study "katabatic wind" at Maitri over Schirmacher Oasis has been examined using the data collected during the 9th Indian Antarctic Expedition 1990-91. The primary results show that katabatic winds are observed in all the months with higher frequency and strength in winter compared to other seasons. A distinction between pure katabatic wind and extraordinary katabatic wind is done based on the wind direction and associated changes in the surface temperature and weather conditions.

7 illus, 3 tables, 5 ref

002401   Krishna Reddy K (Frontier Observational Research System for Global Change, , Yokohama, Japan) : Diagnostic study on vertical structure of tropical precipitating cloud systems using lower atmospheric wind proiler. Indian J Radio Space Phys 2003, 32(4), 198-208.

Temporal variations of vertical structure of precipitating clouds in tropical India have been studied based on the observations of 1.357 GHz lower atmospheric wind profiler (LAWP) at Gadanki. In the presence of precipitating clouds, backscattering from hydrometeors is dominant and the vertically pointing LAWP measures the backscattered energy and the vertical elocities of the hydrometeors directly overhead. These observations yield time-altiude cross-sections of equivalant reflectivity, Doppler velocity and spectral width that illustrate the evolution of precipitating cloud systems. The vertical structure of these three parameters has been used to classify the precipitating cloud systems into three types: convective, transition and stratiform. Diurnal and seasonal variations of the occurrence of precipitating cloud systems show that the precipitation primarily occurs in the afternoon and also the convective and transition clouds are most frequent in the southwest monsoon, while the occurrence of stratiformclouds is predominant in the noreth-east monsoon. Gadanki-LAWP provides means for the development of climatology of tropical precipitating cloud systems. Such climatology is needed to specify diabetic heating rates in large-scale numerical weather prediction and climate nodels.

9 illus, 29 ref

002400   Khole M (NO, India Meteorological Department, Pune-411 005) : Variability of sea surface temperature over Indian Ocean during El-Nino and La-Nina years. Mausam 2003, 54(4), 829-36.

Many recent studies have brought out the importance of Indian Ocean in global climate variability. The variability of composite Sea Surface Temperature (SSTs) over Indian Ocean (10° S - 20°N, 50°E - 100°E) for El-Nina years is analysed. The data period is 1961-97. It is observed that, the composite SSTs over Indian Ocean for El-Nino (La-Nina) years show cooling (warming) during winter season and warming (cooling) during post-monsoon season.

5 illus, 25 ref

002399   Khadri S F R (Geology Dep, Amravati University, Amravati-444 602) : Occurrence of N-R-N sequence in the Malwa deccan lava flow to the north of Narmada region, Madhya Pradesh, India. Curr Sci 2003, 85(8), 1126-9.

3 illus, 3 tables, 18 ref

002398   Kayal J R (Central Geophysics Division, Geological Survey of India, 27 J.L. Nehru Road, Kolkata-700 016) : Seismic tomography for earthquake source areas. J Geophys 2003, 24(1), 37-40.

Seismic tomography structures of source areas of two recent damaging earthquakes, the 1993 Killari earthquake (m_b 6.3) in central India and the 2001 Bhuj earthquake (M_w 7.6) in western India are presented. Large number o0f aftershocks followed the main shocks. The seismic phases (P and S arrivals) of the aftershocks are used for the tomography study. The tomography images revealed lateral heterogeneties in velocity structure; the earthquakes occurred in the high velocity zones at the fault ends.

3 illus, 11 ref

002397   Kandalgaonkar S S;Tinmaker M I R;Kulkarni M K;Asha Nath (NO, Indian Institute of Tropical Meteorology, Pune-411 008) : Diurnal and seasonal variations of point discharge current during thunderstorms at a tropical inland station. Indian J Radio Space Phys 2003, 32(4), 221-8.

The data of point discharge current (PDC) measuements during a total of 65 thunderstorms at Pune (18°32'N, 73°51'E) are analyzed to study the PDC local diurnal variation and some issues related with the current. The analysis shows that about 83% of the total quarter hours occupied by PDC are localized between 1400 hrs LT and 2400 hrs LT and the remaining 17% are sparsely distributed over midnight to early hours in the morning. The net result of this study revealed that PDC is the dominant agent for the negative charging of the earth's surface and should be identified as an active element participating in global electrical circuit. The phase relationsbhip between the positive and negative current during the diurnal period suggests that the active period of current of one polarity has a preferred time of occurrence over the other and by the late night hours the positive charge showed its sustained occurrence over the negative one. The seasonal relationship between storm averaged PDC and monthly mean maximum surace air temperature has also been examined. The comparison of seasonal average amplitued of PDC has suggested a strong positive correlation with the monthly mean maximum surface aire temperature. The average amplitude of PDC during thunderstorm in premonsoon season is found to be about three times higher than those during the monsoon season...

3 illus, 3 tables, 33 ref

002396   Iyengar R N;Raghu Kanth S T G (Centre for Atmospheric and Oceanic Sciences Dep, Indian Institute of Sciences, Bangalore-560 012) : Empirical modelling and forecasting of Indian monsoon rainfall. Curr Sci 2003, 85(8), 1189-1201.

Indian monsoon reainfall datais modelled as a nonlinear time series. It is demonstrated that the propeosed model accounts for about 50% of the inter-annual variability of the rainfall, as observed in eight sets of data represeting All India and regional rainfall values. The model is capable of statistically forecasting seasonal rainfall value one year in advance. The model predicts the drought of 2002, with the help of only antecedent data. Four the year 2003, the predicted All India rainfall value is 82.65°4.88 cm.

5 illus, 9 tables, 18 ref

002395   Dani K K;Ernest Raj P;Maheskumar R S;Devara P C S (NO, Indian Institute of Tropical Meteorology, Pune-400 008) : Aerosol optical characteristics during a summer dust storm in a metropolitan city. Mausam 2003, 54(4), 940-7.

^ccr5 illus, 13 ref

002394   Chattopadhyay N;Samui R P (NO, Meteorological Office, Pune-411 005) : Irrigation requirements of Cotton at different Agroclimatic regions of the country. Mausam 2003, 54(4), 891-900.

Studies were made to find out the irrigation requirements of different varieties of cotton grown at six locations situated in different agroclimatic regions of the country. It is found that there is a considerable variation of irrigation requirements at different growth stages of the crop and also among the varieties cultivated at different regions. In general, the crop requires maximum irrigation either at flowering or boll formation stages. The study reveals that more irrigation is required for the crop grown at Bellary (54.2-56.2 cm), Anand (45.4-63.4 cm) and Kovilpatti (41.0-63.4 cm) compared to that at Akola (15.0-47.3 cm) and Coimbatore (16.9-36.4 cm). Irrigation timing differs considerably due to high degree of variability of rainfall in different regions. Based on probability of rainfall at 70% level, irrigation requirements of cotton has been computed. Specific guidelines are generated to utilise the information for irrigation scheduling of cotton operationally through Agromet Advisory Service.

5 illus, 1 table, 17 ref

002393   Chandra P C;Trivedi B B;Srivastava M M;Adil M;Bhowmick M K (NO, Central Groundwater Board, Northen Region, Lucknow) : Geoelectrical identification of Palaeochannels of river yamuna for Agra districts, Uttar Pradesh. J Geophys 2003, 24(1), 31-6.

Districts Mathura and Agra are replete with brackish to saline groundwater. About 525 electrical resistivity soundings conducted over an area of 220 sq. kms in the western and southeastern parts of these districts respectively, that is towards west of river Yamuna, helped define the spatial disposition of the palaeochannels as elongated resistive bodies. In Mathura district it is oriented in a general NNW-SSE direction, almost parallel to the present day course of river Yamuna, while in Agra it is quite wide and oriented in NNE-SSW. The palaeo-channel delineated towards east and south of Agra hold material of better granularity as compared to those in Mathura district. Also, the channel in Agra district is deeper. These conform with the palaeo-course/abandoned channels of the eastward migrating river Yamuna picked up from satellite imageries. The area covered by these inferred palaeo-channels is about 260 sq. kms. Water wells could be constructed upto a depth of 30-40 m in parts of Mathura and upto about 100 m in Agra in the succinctly defined coarsegrained sediments in the channels containing fresh groundwater zones to suitably cater to the drinking water demand of these cities.

3 illus, 3 ref

002392   Brij Bhushan;Trivedi H K N;Bhatia R C;Dube R K;Giri R K;Negi R S (NO, India Meteorological Department, New Delhi-110 003) : On the persistence of fog over northern parts of India. Mausam 2003, 54(4), 851-60.

In winter there is a spell of about a fortnight, during end of December and beginning of January when persistent fog over plains of northern states of India occurs every year almost regularly. Authors have tried to find the reasons of persistence of this fog praticularly over this area. The reason envisaged here is in the large scale circulation. This diagnosis is for making it a forecasting tool and the study is based on satellite observed cloud imagery received in the VIS and water vapour channels and the derived winds.

5 illus, 1 table, 13 ref

002391   Bijendra Singh;Prajapati S K;Mishra D C (NO, National Geophysical Research Institute, Hyderabad-500 007) : Presence of anomalous crustal root beneath Saurashtra peninsula-inference from gravity modeling. J Geophys 2003, 24(1), 25-9.

Bouguer anomaly map of Saurashtra is characterized by a large number of circular gravity high associated with known volcanic plugs of Deccan magmatism. It also depicts a large wavelength gravity low centered over Jasdan in central Saurashtra which bears an inverse relation with the topography. This low has been interpreted due to mass deficiency resulting from thickening of crust caused by isostatic compensation. Deep seismic sounding (DSS) result along Navibander-Amreli profile clearly indicates variation of Moho depth from 35 Km towards the coast to 42 Km beneath the high lands. Assuming that the compensation is at Moho level, modeling of isostatic regional anomalies in terms of Moho variation along DSS profile has yielded a density contrast of -0.15 g/cm³ which is much less than the expected density contrast of -0.40 g/cm³ across the Moho in normal region. This feature points to either the crustal root is anomalously dense or the upper mantle is anomalously light. DSS result has not indicated any anomalous velocity structure across the Moho. In the absence of conclusive evidence this issue can not be resolved. However, it may be argued that like Saurashtra which had experienced extensive volcanism, an increase in crustal root density may be more plausible explanation for its thickening.

4 illus, 11 ref

002390   Bhattacharya B B;Sinharay R K;Shalivahan (Applied Geophysics Dep, Indian School of Mines, Dhanbad) : MT survey over the geothermal region of Bakreshwar for investigation deeper geo-electrical structure. J Geophys 2003, 24(1), 41-4.

4 illus, 5 ref

002389   Baskar S;Baskar R;Kaushika A (Earth Sciences Dep, ETH, Zurich 8092, Switzerland) : Role of micro-organisms in weathering of the Konkan-Goa laterite formation. Curr Sci 2003, 85(8), 1129-34.

3 illus, 3 tables, 18 ref

001402   Yalcin T;Suner F;Balderer W;Bozkurtoglu E (Mining Faculty, Geology Dep, Technical University of Istanbul, 80626, Maslak, Istanbul, Turkey) : Effects of the 17 August, 1999 earthquake on the heavy metal composition of thermal waters in the marmara region, northwest Turkey: is it a precursor. J Geol Soc India 2003, 62(5), 549-57.

Due to movement of active North Anatolian Fault Zone in the Marmara Region the two main shocks, which were epicentered on Golcuk - Izmit, and Duzce on August 17, 1999 and November 12, 1999 respectively, created the chemical changes on thermal waters of Bursa, Adapazari, Yalova and kuzuluk - Adapazari geothermal areas, which are close to the active fault zone. Field measurements and chemical analyses of these waters from that date to September, 2000 have revealed considerable temporal changes. The trace element contents exhibited variations, particularly as an increase of Pb, Cu and Ni levels, and a decrease of Fe, Mn, Zn contents after the earthquake. These analyses also collected in 2000 showed that, all these changes were temporary an dbecame nearly normal during 2000.

10 illus, 17 ref

001401   Venkataiah C;Shivaprasad K H;Shivakumar K S (Earth Sci Dep, Gulbarga Univ, Post Graduate Centre, Nandihalli-Sandur-583 119) : Governance of mining areas to ensure sustainable development; a comparative study from Sandur Karnataka and Goan areas. Indian Mineralogist 2003, 37(2), 39-42.

Most of the regions endowed (cursed ?) with rich mineral deposits have remained backward in terms of many socio-economic parameters inspite of decades of mining activity. This is attributable to the wrong policies of the governments which encourage only resource drain instead of resource recirculation. Based on the socio-economic data analysis of Sandur and Goan mining areas it is suggested that the general remedial administrative measures for the sustainable development of the backward mining areas is by increasing the recirculation of financial resources as in the case of Goa.

6 ref

001400   Ugarkar A G;Manjunath S;Solankar S N (Geology Dep, Karnatak Univ, Dharwad-580 003) : Geology, mineralization and tectonic setting of the granitoid hosted precambrian Machanur copper deposit, eastern Dharwar craton. Indian Mineralogist 2003, 37(2), 50-63.

Copper mineralization at Machanur is essentially a fracture controlled cataclastite zone within the pink prophyritic granite. The mineralization noted in the metadolerite (diabase) dyke is not significant. The sulphide ore minerals are chalcopyrite, bornite, digenite, chalcocite and pyrite. The oxide minerals are haematite/specularite and magnetite. It is a vein type disseminated deposit for which an epigenetic hydrothermal origin is proposed. The host pink porphyritic granites show intrusive relationship with the well-known Hutti schist belt. These granites are predominantly granodiorite and ademellites and they are characterised as calc-alkaline, meta-aluminous I-type granites. They were emplaced in a tectonic setting environment similar to volcanic are granitoids related to the subduction of oceanic plate underneath the continental plate or island arc. The nature of host granites and their tectonic setting at Machanur area were probably favourable for the copper mineralization. There is a genetic linkage between host granites and copper mineralization.

6 illus, 1 table, 44 ref

001399   Talaneru M (NO, , 2, Bywood Eay Lynwoodl, Perth-6147 Western Australia) : World-class mineral deposits and earth evolution. J Geol Soc India 2003, 62(5), 647-8.

^sscillus, table, ref

001398   Subramani T;Ram Mohan V;Morikiyo T; Srinivasalu S (Civil Engng Dep, Govt Coll of Engng, Tirunelveli-627 007) : Geological and geochemical characteristics of alkaline rocks of koratti, sundamalai and yelagiri plutons, South India. Indian Mineralogist 2003, 37(2), 1-21.

8 illus, 3 tables, 19 ref

001397   Srinivasan V (Publication Div, Geological Survey of India (NER), Kumud Villa Complex, Nongrim Hills, Shillong-793 003) : Stratigraphy and structure of low-grade metasedimentaries in eastern Bhutan and western Arunachal Pradesh. Himalayan Geol 2001, 22(2), 83-98.

The low-grade metasedimentaries exposed between sedimentary belt in the south and Central Crystalline in the north can be broadly subdivided into five groups namely Bomdila Group, Rupa Group, Thungsing (Bichom) Group, Shumar Group and Buxa Group. The oldest Bomdila Group comprising gneisses of granitic composition (Bomdila gneiss) and a highly tectonised sequence of quartzites and Phyllites (Tenga Formation) is exposed in the core of a westerly plunging regional antiform, named as Narphung antiform. Rupa Group, which structurally overlies Bomdila Group with a tectonic contact, comprises of quartzites, phyllites, dolomites and pebble bed. It is well exposed in the western closure and northern limb of Narphung antiform and also in the core part of Rupa synform, which is a mega digitation in the northern limb of Narphung antiform. Thungsing Group comprising massive white gritty and feldspathic quartzites (Thungsing quartzite) and phyllites with or whithout rock fragments (Diuri phyllite), structurally overlies Rupa Group with a tectonic contact in the closure part of Narphung antiform. In the southern overturned limb of Narphung antiform, this group structurally underlies Bomdila Group as an inverted sequence, whereas in the northern limb, it is missing due to Main Central Thrust (MCT). Further west of the closure part of Narphung antiform (i.e. in down the plunge direction), the outcrop pattern of Thungsing Group reveals refolding of this earlier antiform to generate two NE plunging later mega folds, namely Shumar synform and its complimentary Kenkhar antiform. Shumar Group comprising gray quartzites, phyllites, impure limestone (mostly in rhythmic alternation), structurally overlies Thungsing Group with a tectonic contact and it is well exposed in the core of Shumar synform. Thus Bomdila Group is in the lower part of tectono-stratigraphy and Shumar Group is in the upper level. Buxa Group comprising quartzites, phyllites, limestones and dolomites is exposed in the southwestern part of the study area, structurally underlying Thungsing Group, in the inner core of Kenkhar antiform.

10 illus, 1 table, 27 ref

001396   Singh S (Earth Sciences Dep, Indian Institute of Technology, Roorkee-247 667) : Conventional and SHRIMP U-Pb Zircon dating of the chor granitoid, Himachal Himalaya. J Geol Soc India 2003, 62(5), 614-26.

Conventional zircon U-Pb analyses of optically clear multi-grain fractions from the Chor Granitoid sample CH 1/1 provide a complex pattern with eight points yielding a referencd line with an upper intercept age of c. 910 Ma and large scatter. Three zircon fractions from the more deformed sample C 4/11 of this body define a discordia line with an imprecise upper and lower intercerpt ages of 859±¹¹⁹₂₇ Ma and 460±264 Ma respectively. On the other hand, SHRIMP analyses of carefully selected core and irm of CH 1/1 zircon give magmatic rim/grin age of 823±5 Ma with zircon cores having more than 5% discordant ²⁰⁷Pb/²⁰⁶Pb ages ranging from <126>900 Ma to <126> 1560 Ma/. The presence of older cores indicate that 0.9 Ga age obtained from conventional TIMS U-Pb technique is probably a mixed age of magmatic and inherited zircons.

5 illus, 4 tables, 52 ref

001395   Singh A K (Geology Dep, Banaras Hindu University, Varanasi-221 005) : Petro-chemical behaviour and potential utilisation of the coal deposits of yellandu coalfield, Andhra Pradesh (India). Ultra Scient phys Sci 2002, 14(1), 136-8.

Yellandu coalfield is situated outside the western margin of Pranhita-Godavari basin. These coal deposits are Permian in age and coal seams occur in association of Barakar sandstones. An attempt has been made to study the petro-chemistry of Yellandu coals and based on petrographic and geochemical properties their utilisation has been discussed.

^ssc11 ref

001394   Singh A K (Geology Dep, Banaras Hindu University, Varanasi-221 005) : Geochemical characteristics of permian coals of Chirimiri coalfield, Sarguja district, Chhattishgarh, India. Ultra Scient phys Sci 2002, 14(1), 31-8.

The Chirimiri coalfield is a member of Son valley coalfields and situated in Sarguja district of Chhattisgarh. The coal samples were collected from working coal faces of Chirimiri coalfield and were processed to know the geochemical behaviour of these coals. The proximate constituent (volatile mater, d.a.f. basis) indicate that these coals are sub-bituminous `A' to high volatile `B' bituminous in rank. The chemical analyses of coal were used to establish the distribution, association and relationship between major inorganic elements such as - Si, Al, Fe, Ti, P, Mg, Ca, S, Mn. The distribution of major and minor elements in coal appears to be related to the amount of mineral matter occurring in coal and its mineralogical composition. The principal component of Chirimiri coals are silica and alumina. The Si/Al and Al/Ti ratios have been used to interpret the depositional environment and source. The Si/Al ratio indicates the occurrence of high content of mixed layer clay mineral, where as Al/Ti ratio suggests that acidic igneous rocks have contributed mainly to the elastic materials occurring in association of the coal seams of Chirimiri coalfield.

1 illus, 5 tables, 13 ref

001393   Sahu R;Anil Kumar;Subbarao K V;Walsh J N; Biswal T K (NO, Indian Institute of Technology, Mumbai-400 076) : Rb-Sr age and Sr Isotopic composition of alkaline dykes near Mumbai: further evidence for the deccan trap-reunion plume connection. J Geol Soc India 2003, 62(5), 641-6.

Reports a new Rb-Sr isochron age of 64.9±0.8 Ma for the West Coast lamprophyre at Murud, south of Mumbai and trace element and Sr isotopic composition (0.70384-0.70419) for alkaline, ultrapotassic and basic suites of dykes NE of Kalyan near Mumbai intruding the Deccan basaltic flows. The age of lamprophyre is synchronous with the bulk of the Deccan Trap activity and nearly coincides with the K/T boundary. Also, the initial Sr isotopic composition is similar to the Deccan and Reunion basalts suggesting a genetic connection of the Reunion plume.

^ssc4 illus, 24 ref