004403   Ramasamy V;Dheenathayalu M;Ravisankar R; Ponnusamy V;Anandalakshmi K (Physics Dep, Annamalai Univ, Annamalainagar-608 002) : Spectroscopic analysis of some typical rock samples of Western Ghat, Tamil Nadu. Bull pure appl Sci-Sect F 2002, 21(2), 83-8.

A simple and convenient analytical method for simultaneous multi element determination of rock samples has been investigated by ICP-AES-MS. The rock samples collected at various heights of Western Ghat, Tamilnadu were estimated for transition and rare earth elements. The samples were prepared by acid digestion method. The alkali elements were also determined by flame photometer techniques as Na, K & Ca play prominent role in feldspars. Both transition and REE were discussed on their distribution with height. The quantity estimation was compared with USGS standard rock values.

5 illus, 5 tables, 7 ref

004402   Ramasamy V;Dheenathayalu M;Anandalakshmi K; Ponnusamy V;Ravisankar R (Physics Dep, Annamalai Univ, Annamalainagar-608 002) : Characterisation of quartz using FTIR. Bull pure appl Sci-Sect F 2002, 21(2), 89-94.

The method of infrared study was used as a tool to identify the mineral content of the rock samples. The samples were collected at various areas of Tamilnadu and the KBr pellet technique was employed. The quartz orthoclase, microcline, albite, gibbsite, illite, maghemite, magnetite kaolinite, vermiculite and palygorskite are identified as the minerals. The crystallinity index and extinction coefficient of quartz are also calculated and compared.

3 illus, 1 table, 9 ref

004401   Ramasamy S M (Centre for Remote Sensing, School of Earth Sciences, Bharathidasan University, Tiruchirapalli) : Designing of artificial recharge schemes in hard rock aquifer systems. J Indian Wat Wks Ass 2002, 34(2), 141-7.

Scientists, technocrats and planners all over the world have unanimously agreed that artificial recharge is the only way to replenish the fastly deteriorating water table. But designing of artificial recharge schemes is a ticklish art and in which many scientific criteria will have to be followed such as, identification of suitable sites, detection of site-specific mechanisms, estimation of quantum of allowable recharge, estimation of available surface water resources, etc. so as to make such artificial recharge schemes fully viable and effective. The same is narrated with the help of a study carried out in Ayyar basin, Tamilnadu, which represents a typical hard rock aquifier system.

9 illus, 1 table, 13 ref

004400   Raghav S S;Tripathi T;Sharma C S;Makhijani S D;Satya Prakash (Central Pollution Control Board (CPCB), Ministry of Environment & Fore, , Parivesh Bhawan, East Arjun Nagar, Delhi-110 032) : Trace metal characterization of environmental matrices by atomic absorption spectrophotometric technique. Res J Chem Envir 2003, 7(1), 8-13.

The anthropogenic activities are influencing the trace metal loading of the environment and of concern since serveral trace metals are toxic in nature. The detection of trace metals in environmental matrices are accomplished by various methods viz. Colorimetric, polarographic, inductively coupled plasma, atomic absorption spectrophotometry etc. but trace metals analysis using atomic absorption spectrophotometric technique is relatively simple, versatile, accurate and free from interferences. The detection of presence of various trace metals such as Cd, Cr, Cu, Ni, Pb and Zn in various industrial effluents, water and sludge from textiles, refinery, electroplating and several other industries are regularly carried out through atomic absorption spectrophotomertry for characterization of effluents during environmental assessment and monitoring. The analytical aspects of trace metals in environmental matrices by atomic absorption spectrophtometry have been discussed.

5 tables, 4 ref

004399   Pavanaguru R;Venugopal Reddy K (Geology Dep, Osmania Univ, Hyderabad) : Quartz deposits of Yellandu area, Khammam district, A.P. India. Bull pure appl Sci-Sect F 2002, 21(2), 77-82.

Quartz, an industrial mineral, has its own place of importance in the area of mineral-based industries, especially supplying intermediate products for metallurgical and allied industries. The quartz deposits of Yellandu area in Khammam district of Andhra Pradesh occur over a strike length of 12 Km. along the northern extension of 'shernawal outlier' (R. Bruce Foote 1885). The deposits are structurally controlled along a NNE-SSW trending shear zones and occur as fissure fillings in a fault trap. These deposits were studied in detail in regard to its nature of occurrence, distribution, chemical quality and thermal stability. The study was conducted based on the strategic location of these deposits in close proximity to the Godavari valley coal fields (GVCF) of Khammam district, A.P.

1 illus, 2 tables, 11 ref

004398   Mazumdar A C;Das D N (Geological Sciences Dep, Gauhati Univ, Guwahati-781 014) : Compositional characteristics of charnockites and basic granulites in the transitional granulite terrain around Satnuru in southern Karnataka. Bull pure appl Sci-Sect F 2002, 21(2), 65-71.

Charnockites and basic granulites which occur in the Satnuru area, Karnataka, India are genetically not co-magmatic. Acid charnockites preserve a calc-alkaline trend whereas basic granulites have tholeiitic affinity. Intermediate charnockites share both the acid charnockites and basic granulites of the area in trace element composition and they are generated as hybrid rocks. The rocks exhibit a strong metasomatic impression in their chemical characters. The K/Rb ratio, the only available monitor of depletion of the granulites in the area is variable and appreciably higher than average continental crust and can not be a primary magmatic signature. Such a depletion of Rb relative to K in the rocks could be imposed due to granulite facies metamorphism of the rocks but it does not indicate that the transitional granulites can be more depleted in Rb than the 'proper' granulites as suggested by some workers.

4 illus, 1 table, 10 ref

004397   Hassan S Z (Geology Dep, Aligarh Muslim Univ, Aligarh-202 002) : Geomorphological studies in parts of the central Ganga plain using IRS 1A data. Bull pure appl Sci-Sect F 2002, 21(2), 57-63.

Kasganj sub-division forms an important part of the central Ganga basin, bounded by the river Ganga in the north and river Kali in the south. The area has flat topography with some undulations leading to an average fall in the elevation as 0.70m/km, with the regional slope due southeast. Topographically, the area exhibits four distinct units viz; the low valley of the river Ganga, the central upland, the low valley of the river Kali, and the southern upland, differentiated by their own characteristic features. The visual interpretation through IRS IA data divides the area into three geomorphic zones namely, the active channel of the river Ganga, the younger alluvial plain, and the older alluvial plain. Besides, abandoned channel, old meanders, point bars and ravines have also been recognized. These landform features have lead the entire sub-division to be divided into three soil regions separated by their peculiar distinguishing physical characteristics.

4 illus, 15 ref

004396   Gogoi A;Das P K (Geological Sciences Dep, Gauhati Univ, Guwahati-781 014) : Studies on zircons from the Kopili sandstones occurring in and around Sonapur, Jaintia Hills district, Meghalaya. Bull pure appl Sci-Sect F 2002, 21(2), 95-103.

The heavy mineral 'Zircon' of the Kopili sandstones of the Kopili Formation occurring in and around Sonapur, Jaintia Hills district, Meghalaya was studied to determine the provenance, depositional history of the sediments. For this purpose statistical analysis of the zircon grains was done and their morphological characters were also studied. The length frequency, breadth frequency and elongation quotient frequency diagram of zircon (statistical analysis) indicate two or more diverged source and poor sorting nature of the sediments. The scatter diagram of zircon is also indicative of nearer provenance and hence shorter transportation of the zircon, implying short distance of transportation of host sediments, carried mostly from the Meghalaya plateau. The study of primary and secondary growths on zircons also indicate dual nature of the origin of the sandstones. The overgrowth and outgrowth pattern suggest anatectic or metasomatic gronitic origin of the sandstones which is also supported by the parallel growths. However, the necked zircon, bending and vein structure of some zircon grains indicate metamorphic provenance of medium to high grade metamorphic rocks. But some grains were rounded and subrounded which suggest reworked nature of some of the sediments.

6 illus, 4 tables, 14 ref

004395   Dissanaike G (Dep of Phys, Univ of Peradeniya, Peradeniya, Sri Lanka) : Sunrise from high altitude in clear and polluted skies. Phys Educ 2002, 18(3-4), 267.

A few photographs of sunrise taken at high altitudes on two occasions, when the skies were clear and clean over the Indian Ocean, and when the skies over the Middle East were intensely polluted as a result of the Kuwait oil fires of 1991 have been presented. The colours seen in the sky at high altitude on these two occasions are in striking construct, conveying an important message concerning atmospheric pollution. A most colourful picture of a sunrise taken from amidst the hills of Kandy shows Nature as its best, and confirms that the atmosphere over the region is clean and free of pollution.

6 illus, 2 ref

004394   Annadurai B;Arunachalam N;Mahalingam K (Physics Dep, Aditanar College, Tiruchendur-628 216) : Influence of tank silt on the physical properties of Theri-soils. Bull pure appl Sci-Sect F 2002, 21(2), 73-5.

The red dunal sandy waste lands called 'Theri lands' are located along the coastal areas of Tuticorin and Tirunelveli districts of Southern Tamilnadu. Proper management of the land is difficult because of its poor quality structure, low nutrition, meager moisture holding cpacity, low value of organic content, and high value of hydraulic conductivity. The objective is to nurse the soil back to health and reclaim the soil, tank silt is amended with the soil to reduce the fertility constraints of the soil. By ameliorating the tank silt with the soil, different physical parameters which influence the intensive cultivation are estimated and their relationships predicted.

1 table, 8 ref

003296   Vinod Kumar K;Bhattacharya Asis (NO, , National remote Sensing Agency, Balanagar, Hyderabad-500 037) : Geological evolution of Mahanadi delta, Orissa using high resolution satellite data. Curr Sci 2003, 85(10), 1410-12.

3 illus, 4 ref

003295   Valdiya K S (NO, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore-560 064) : Reactivation of Himalayan frontal fault: implications. Curr Sci 2003, 85(7), 1031-40.

Youngest of the five terrane-defining faults, the Himalayan Frontal Fault (HFF) is a series of reverse faults that demarcates the boundary of the Siwalik front of the Himalayan province with the alluvial expense of the Indo-Gangetic Plains. Originated about 1.6 million years ago, it has truncated and attenuated the Siwalik domain. Over large tracts, it is either concealed under younger sediments or has as yet not reached the ground surface and is therefore a blind fault. The nature of this frontal fault varies along its length. Where the hidden ridges of the Indo-Gangetic basement impinge the himalayan, the mountain front is ruptured and the HFF is repeatedly reactivated. In the sectors intervening these ridges, it is not expressed on the surface, but the ground of the adjoining Indo-Gangetic Plain is sinking, the rivers are shifting their coarses and a large tract of the land is waterlogged and characterized by marshes or ponds and by strong seismicity. The northern part of the Indo-Gangetic Plains in the proximity of the ruptured mountain front is also experiencing buildup of tectonic stress. The HFF traces the frontal line of the detachment plane along which the Indian plate is sliding under the Himalaya and generating earthquakes.

12 illus, 21 ref

003294   Thapliyal V;Rajeevam (India Meteorological Department, , Pune-411 005) : Updated operational models for long-range forcasts of Indian summer monsoon rainfall. Mausam 2003, 54(2), 495-504.

Based on operational 16 parameter models, the India Meteorological Department, since 1989, has been issuing the long-range forecasts for monsoon rainfall (June-September) for the country as a whole. Qualitative forecasts of category of monsoon (Deficient, normal and excess) proved accurate on all the 11 years (1989-99). However the errors in the quantitative forecasts, particularly from 1996-99 were more than the model error of ±4%. Therefore the operational 16-parameter models (parametric and power regression) were updated by replacing four predictors whose relationship with monsoon rainfall has weakened in recent years. The new predictors introduced into the models are Arabian Sea SST, South Indian Ocean SST, Europe Pressure Gradient and Darwin Pressure Tendancy. The model constants were recalculated with the data for the period 1971-95. The performance of the updated model was found to be far better especially during the recent years. The absolute ean error of the forecast from the updated model for the period 1991-99 was 3.2% as against 7.0% of the operational forecasts. As these updated models showed promise, they were introduced in 2000 for issuing the operational long-range forecasts of Indian summer monsoons rainfall.

5 illus, 4 tables, 28 ref

003293   Sultan S A R;Elghribi N M (Dep of Marine Science, Faculty of Science, P.O. Box 2713, Doha, Qatar) : Sea level changes in the central part of the red sea. Indian J Mar Sci 2003, 32(2), 114-22.

Daily means of sea level and atmospheric forcing over a period of three years (1991-1993) at Jeddah are examined by spectral and regression methods. The analysis reveals the presence of a large annual and a semi-annual component in the time series. Average amplitudes of the two signals in the sea level changes are 19 and 8 cm, respectively, and account for 58% of the total variance. The two signals are induced by the combined effect of wind stress and evaporation rate. Wind stress plays a major role in inducing the annual cycle. Sea level is inversely related to the evaporation rate only during the transition periods. Isostatic response of sea level is limited, 4% of the total variance, and is frequency dependent with observed period of 9 days. Analysis of daily residuals shows that about 78% of the variance can be modeled by a first order auto-regressive model AR (1).

10 illus, 2 tables, 25 ref

003292   Srivastava A;Tiwari R N;Mishra D;Kshitij Mohan (Dep of Geology, Banaras Hindu University, Varanasi-221 005) : Studies of glass sands occurring around Shankargarh, district-Allahabad with reference to its economic viability. J scient ind Res 2003, 62(9), 931-43.

The sands in the area are predominantly whitish. However, other colours viz. pink, light yellow, yellow, brown and red are also commonly found. More than 60 samples of glass sand representing the vertical and lateral variations of the lithological units were collected from different parts of the Shankargarh district in Allahabad were collected for grain size, mineralogical and geochemical analyses. The grain size analysis reveals that the majority of the grains are rounded, coarse to fine size grade, well sorted, finely skewed and platykurtic. Mineralogical study of the selected glass sand samples shows the presence of light minerals, i.e. quartz, mica and chert and heavies-rutile, staurolite, tourmaline, and zircon. Opaques include magnetite and ilmenite. Geochemical analysis of these sands reveals a variation in SiO₂ in between 97 per cent and 99.01 per cent, whereas Fe₂O₃ from 0.14 per cent to 1.41 per cent and Al₂)₃ 0.12 to 1.89 per cent. The percentage of iron decreases with the increase of depth, thereby at the base white glass sand of purest variety is met with. Impurities in the form of iron oxide, glistening specks of mica, etc., have been observed in the glass sands. By treatment and benefication, ironand aluminium contents of the glass sands of the area can be reduced for the purpose of making colourless glass. These sands can also be used for makingthe different type of glass, i.e., lime glass, lead glass and silicate glass. The glass sands in the area have been found under thin cover of soil with a gentle ground slope. This has provided more time and opportunity for the rain water to percolatee through and thereby facilitate the disintegration of the parent rock in the dry summer season.

3 illus, 7 tables, 14 ref

003291   Srinivas K;Revichandran C;Thottam T J; Maheswaran P A;Mohamed Asharaf T T;Murukesh N (NO, National Institute of Oceanography, Regional Centre, P.O. Box-1616, Cochin-682 014) : Currents in the Cochin estuarine system [southwest coast of India] during March 2000. Indian J Mar Sci 2003, 32(2), 123-32.

Analysis of current meter data collected in the Cochin estuarine system (southwest coast of India) has been made, to understand variations of currents in the estuary for spring and neap tidal phases during March 2000. The currents were strongest at an interior station as compared to stations closed to the mouth of the estuary. The currents were also found to be rectilinear in nature at most of the stations. The observed currents were dominated by tidal signals-spring phase was dominated by semi-diurnal and neap phase by diurnal tidal currents.

7 illus, 5 tables, 18 ref

003290   Shirodkar P V;Xiao Y K;Lu Hai (NO, National Institute of Oceanography, Dona Paula, Goa-403 004) : Boron and Chlorine isotopic signatures of seawater in the central Indian ridge. Curr Sci 2003, 85(3), 313-20.

Isotopic ratios of boron and chlorine were measured in the upper 2000 m water column of the Central Indian Ridge from two tectonically active areas, one at 5°S and other at 10°S which coincided with the spreading regime of the Central Indian Ridge (CIR). Boron and Chlorine isotopic measurements were made using positive thermal ionization mass spectrometry (TIMS) of Cs₂BO₂⁺ and Cs₂Cl⁺ ions respectively, mainly to understand their isotopic behaviours to elucidate the consistency of boron and chlorine isotopic compositions of seawater in the oceanic regime. The boron isotopic compositions (δ¹¹B values) varied from 37.77% to 39.54% at 5°S and from 37.75% to 39.82% at 10°S with considerably heavier values below 300 m depth. The relatively lighter δ¹¹B values of seawater within the thermocline in the upper 300 m layer gave an average δ¹¹B value was 39.3%. The release of boron from remineralized organic matter and other unknown factor appears to influence the δ¹¹B values in causing variations in the upper 300 m layer. The chlorine isotopic composition (δ³⁷Cl) of seawater lies within ±1% and indicated difference in their vertical variations at 5°S and 10°S. The δ³⁷Cl values ranged from -0.53 to 0.94% at 5°S and from 0.10 to 0.59% at 10°S with most of the lighter values (av.0.06%) below 300 m depth, showing a trend opposite to that of boron isotopic variation. The observed heavier δ³⁷Cl values (av.0.64%) in the upper layer have been attributed to an increase in evaporation to precipitation ratio of seawater that alters the isotopic behaviour of chlorine in the ocean.

6 illus, 4 tables, 27 ref

003289   Seetharam K (NO, , Flood Meteorological Office, Jalpaiguri) : Correlation structure of daily rainfall over teesta catchment. Mausam 2003, 54(2), 447-52.

R-estimates were widely used to know the spatial distribution of daily rainfall in various weather situations. The cross-correlation analysis has been performed to understand the variability of daily rainfall during monsoon months over Teesta catchment. For the purpose of study, ten station's daily rainfall data for the period 1995-2000 has been utilized. The analysis of estimated cross-correlation field entirely for four months of monsson suggested that the rainfall area during the monsoon months extends up to 60-80 km distance in north-south, northnortheast-southsouthwest and 50 km in the remaining directions. The pattern of daily rainfall can best be represented as interaction of two ellipses, one with major axis in the direction of northnortheast southsouthwest (75<144 N-80<144 N/115<144 S-100<144 S)and another with major axis in the northnorthwest-southsoutheast(110<144 N-120<144 N/70<144 S-60<144S) direction and are seen traversing in the directions of major uplands. It is also found that the estimated correlation coefficients decreased with distance in all directions other than in the directions major axes of elliptical patterns of spatial distribution of correlation coefficients and became insignificant beyond 50km. It is also seen that in hilly regions of the catchment, the moisture feed is blocked further in northnortheast direction (65<144N) due to presence of uplands southsouthwest of it.

2 illus, 4 tables, 3 ref

003288   Roy S S;Roy Bhowmik S K (India Meteorological Dep, , Lodi Road, New Delhi-110 003) : Evaluation of thermodynamics of the atmosphere in relation to pre-monsoon convective activity over north India. Mausam 2003, 54(2), 397-406.

Explores the relationship between the vertical structure of the atmosphere and variation of deep (precipitating) convection over north India during pre-monsoon months using data for the year 2001. From the model analysis field, CAPE and other thermodynamic parameters for Kolkata, as representative of east India and Delhi, as represrentative of northwest India, are computed. The vertical vorticity profiles for these two stations have also been calculated. The study reveals that both for Kolkata and Delhi CAPE is poorly correlated with the rainfall amount. However, the encouraging result is that it has reasonably good skill score (bias and threat scores) to explain occurrence or non-occurrence of convective activity on the subsequent day. Time evolution of vertical structure of atmosphere indicates that nature of convective activities over Kolkata changes as the season advances. The rainfall becomes more dependent on lower tropospheric vorticity and moisture conditions become conductive for deeper convection and taller convective clouds to form with the advance of the season due to a significant increase in the lower tropospheric vorticity. This strengthening of the dynamic support to convective rainfall may be because of the pre-monsoon synoptic pattern becoming more pronounced with the progress of the season. Over Delhi, rainfall dependence on moisture is more at the beginning of the season. As for Kolkata, in this case also character of convection changes as season progress, with increasing dependence of rainfall on lower tropospheric vorticity field. However, dynamic support is not an important initiator of convection over Delhi. Suggests that, the day to day drying of the atmosphere in the lower levels over Kolkata is due to subsidence of upper layer dry air while over Delhi, horizontal advection is mainly responsible for the change in moisture content of the atmosphere.

4 illus, 6 tables, 14 ref

003287   Roy Bhowmik S K (India Meteorological Department, , New Delhi-110003) : Evaluation of cyclone genesis parameter over the Bay of Bengal using model analysis. Mausam 2003, 54(2), 351-8.

The thermodynamical condition necessary for tropical cyclogenesis are commonly satisfied over most of the oceans while the dynamical conditions have large day to day variations.Zehr (1992) designed a parameter known as Genesis Parameter (GP) which involves three dynamical conditions of the environment. An intercomparison of Genesis Parameter associated with some recent developing and non-developing low pressure systems is made with a view to get an idea of its threshold value for the Bay of Bengal. Model analysis field at the resolution 1° X 1° lat./long. is used for derivation of GP. The study reveals that GP value around 20 X 10^-12sec^-2 against T. No. 1.5 has the potential to develop into a severe cyclonic storm. Both for the Orissa super cyclone of October 1999 and the Bangladesh very severe cyclonic storm with core of hurricane winds of May 1997, GP attained its peak intensity at T. No. 3.5. There was a time lag of about 24-36 hours between GP max. and highest intensity of the system. It appears to provide useful predictive signals for the operational cyclone warning work.

6 illus, 5 tables, 7 ref

003286   Robaa S M (Astronomy and Meteorology Department, Faculty of Science, Cairo Univarsity-Giza, Egypt) : On the estimation of global and diffuse solar radiation over Egypt. Mausam 2003, 54(2), 511-20.

Measurements of global, H, diffuse, D, solar radiation on a Horizontal surface and sunshine duration, n, at nine meteorological stations have been used to examine the validity of some methods of the estimate global and diffuse solar radiation. In order to improve the obtained results, for predictions purposes, the investigated area of Egypt has been divided into five regiond represented by the nine selected stations (in cold and hot seasons). An appropriate regional parameter, K, of an imperical relation of Barbaro et al. has been determined for each region. The agreement between measurement and estimated values is remarkable. The maximum possible error of estimated values does not exceed 9.6%. It is seen that the modified formula gives precise estimations for global solar radiation at any Egyptian locality. Relation between the diffuse fraction, D/H, and the relative duration of sunshine, n/N, are also determined for each region. Good agreement between the measured and estimated values applying the obtained relations has been found. Therefore, the relations are recommended for use at any location in Egypt. A comparative study for the global and diffuse solar radiation over different sites in Egypt has been made.

2 illus, 6 tables, 17 ref

003285   Rajendran K;Rajendran C P (NO, , ) : Seismogenesis in the stable continental regions and implications for the hazard assessment: Two recent examles from India. Curr Sci 2003, 85(7), 896-903.

Occurrence of three earthquakes in the Indian stable continental region (SCR) during 1993-2001 has triggered many questions on the nature of recurrence, charcteristics size and mechanisms. Seismogenic sources in Killari an Kachchh may be considered as representatives examples of two distinctive classes of SCR earthquakes, the former originating on discrete faults in the unrifted part of the crust, and the latter associated with larger structures in an ancient rift. Seismic-hazard evaluation in these regions must take into account the inherent characteristics of these causative structures, which are reflectd in their respective seismic productivities. While the Killari-type earthquakes are of moderate size (Mθ6) and repeat over intervals of several tens of thousands of years, the Kachchh-type earthquakes are larger (M<62>7), and may have much shorter recurrence intervals. The observation that multiple sources related to unexposed seismogenic structures with unknown seismic histories exists in the Kachchh region, calls for concerted efforts to study this important seismogenic zone in SCR India.

^ccr6 illus, 47 ref

003284   Rajendra prasad;Hari Singh;Lal B (NO, , Meteorological Office, New Delhi) : Persistence, intensification and recession of meteorological drought over India during 1987. Mausam 2003, 54(2), 453-62.

The persistence, intensification and recession of districtwise meteorological drought over India during 1987 have been studied using cumulative weekly rainfall deficiencies (%) from the normal during the southwest monsoon season (June-September) for 355 districts of India. These features have been analysed in northeast, North and Penninsular India during three distinct phases of southwest monsoon, viz., progress(9 weeks), active(6 weeks) and retreat phase (3 weeks). A prolonged dry spell emerged over a vast region of northwest India up to a mid August due to the absence of major weather systes, leading to intense drought conditions. Mixed mode persistence prevailed throught monsoon season over 65 districts. Unimode persistence of severe intensity occured in 209 districts over different parts of India. Intensification of drought was more prominent in north India affecting 67% districts. Recession of drought occured in 40% and more districts in northeast and Penninsular India respectively.

7 illus, 1 table, 9 ref

003283   Pai D S (India Meteorological Dep, , Pune) : Teleconnections of Indian summer monsoon with global surface air temperature anomalies. Mausam 2003, 54(2), 407-18.

Evolution of prominent teleconnection patterns in the monthly global gridded surface air temperature anomalies associated with the interannual variability of Indian Summer Monsoon Rainfall (ISMR) were examined using data for the period 1901-98. Useful precursory signals for the subsequent ISMR were also identified. Teleconnection patterns showed significant signals from various geographical areas all over the globe. In the land, the temperature distribution over the Eurasian region, which is significantly influenced by the Northern Atlantic Oscillation (NAO) showed the most significant teleconnection with the ISMR. In the oceanic region, teleconnection signals were observed from most of the tropical ocean basins.

5 illus, 1 table, 29 ref

003282   Orlov A M (NO, Russian Federal Research Institute of Fisheries & Oceanography (VNIRO), 17, V. Krasnosel'skaya, Moscow, 107140, Russia) : Impact of eddies on spatial distributions of groundfishes along waters off the northern Kuril Islands and southeastern Kamchatka (north Pacific Ocean). Indian J Mar Sci 2003, 32(2), 95-113.

Distributional peculiarities of groudfishes, inhabiting the Pacific waters off the northern Kuril Islands and southeastern Kamchatka, where three quasi-stationary eddies occur, have been considered. The possible influence of eddies on occurence of groundfishes are discussed. Existing eddies off underwater plateau and small banks in the southern part of the study area provides specific environment (bottom relief, temperature and currents) for fish inhabitation essentially differed from that of adjacent waters. Composition of ichthyofauna, off plateau area, is very specific. There are several species widely distributed in the North Pacific that were caught only within plateau area. Some species widely distributed in the Pacific waters off the Kuril Island and eastern Kamchatka are abundant only in the area off plateau and banks. Feeding aggregations of plankton-feeders Atka mackerel and Pacific Ocean perch (these species are targets of specialized fishery) occur here throughout the year, probably related to fine foraging conditions in the enlarged plankton biomass in the area. Pelagic larvae and juveniles of some fishes, permanently dwelling the area, probably grow there until settlement. The study area serves as nursery ground for some fishes, which spawn outside the area. Currents transport pelagic larvae and juveniles of these species from main spawning grounds (eastern Kamchatka and Paramushir Island coasts) to the south. The larvae fall into eddies, inhabit these waters until settlement, feed on plateau slopes and later with increase in size start reverse migrations. Thus, eddies affect occurence and distributional patterns of various groundfish species, having different types of life cycle.

15 illus, 1 table, 65 ref

003281   Murugan A;Ramasamy M S (NO, Suganthi Devadason Marine Research Institute, 44-Beach Road, Tuticorin-628 001, Tamil Nadu) : Biofouling deterrent activity of the natural product from ascidian, Distaplia nathensis [Chordata]. Indian J Mar Sci 2003, 32(2), 162-4.

Growth of marine sedentary organisms causes notable damage to ship-hull, harbour structures and industrial cooling and filtration systems. TBT based antifouling paints are widely used worldwide and is to be phased out by the year 2008 because of its adverse effect on non-target organisms. Effort are therefore being made to develop alternative eco-friendly antifoulant paints. The crude methanol: water extract of the ascidian, Distaplia nathensis showed antimicrobial activity against 12 out of 14 bacteria screened. At a concentration of 0.1 mg/ml, the crude extract completely inhibited the byssal production and attachment in the mussel Perna indica. The EC_50> and LC₅₀ were found to be 50±6.45 μg/ml and 150±19.2 μg/ml respectively. The gradient partition showed high polar nature of the active component. The indication of non-toxic nature of the extract in the toxicity assay and the broad spectral antimicrobial activity has revealed that it could be a potential source of the antifouling compound.

^ssc1 tables, 15 ref

003280   Mukherjee S (Dep of Earth Sciences, Indian Institute of Technology, Roorkee-247 667) : Modelling fluid flow in the mild oceanic ridge hydrothermal system. Curr Sci 2003, 85(3), 239.

^ssc1 ref

003279   Morwal S B (NO, Indian Institute of Tropical Meteorology, Pune-411 008) : Structure of the convective boundary layer- a method to delineate the sub layers. Mausam 2003, 54(2), 529-38.

Introduces a different method to delineate the different sub layers in the Convective Boundary Layer over the north Indian Oceanic regions during the summer monsoon season. The all available data set (only aerological observations) from the MONSOON-77 experiment during the June-August 1977 over the Arabian Sea (Phase IA and IB), Equatorial Indian Ocean (Phase II) and Bay of Bengal(Phase III) regions have been considered to demonstrate the usefulness of the above method. The vertical structure of the Convective Boundary Layer revealed the four layered structure viz. surface layer, sub cloud layer, cloud layer and capping stable layer. These layers could be seperated from each other by utilizing the averaged vertical profiles of saturation pressure deficit(P^<42>, hPa) and mixing parameter (β, dimensionless). The CBL topis marked by minimum value of P^<42>. Revealed that, in general, the extent of surface and sub cloud layer over the north Indian Oceanic regions is up to 1000 hPa and 950 hPa respectively. Also, it is observed that the cloud layered depth varies during the phases IA, IB, II and III. The investigations revealed that the depth of the CBL is up to 650 HPA during all the three phases over the ships.

5 illus, 4 tables, 17 ref

003278   Mishra R K;Shaw B P;Das S K;Srinivas Rao K; Chaudhury S B;Rao K H (NO, Institute of Life Sciences, Nalco Square, Bhubaneswar-751 023) : Spatio-temporal variation of optically active substances in the coastal waters off Orrisa from Rushikulya to Dhamra (east coast of India). Indian J Mar Sci 2003, 32(2), 133-40.

Surface concentration of gelbstoff and vertical structure of chlorophyll-a (chl-a) and pheophytin-a were determined in coastal waters off Orrisa along five transacts. Depth-dependent concentrations of NO₃^- and PO₄^3- at several stations along the paradip transact (Tr.), Tr.-IV were also studied. The concentration of chl-a differed greatly between various sampling stations. Along a transact the concentration of the pigment was mostly higher in the near-shore waters (station depth ≤ 20 m) than in the offshore waters (station depth <62> 20m), and irrespective of the depth of the sampling stations and the transacts, the pigment was more concentrated towards the bottom than towards the surface (0 m) and sub-surface (10/15 m) layers of the water column. Similar to chl-a both NO₃^- and PO₄^3- were found to be more concentrated towards the bottom than towards the surface of the water column, but none of them really regulated the growth of phytoplankton. Pheophytin-a constituted mostly less than 5-7% of the total chl-a value in the surface waters, and the concentration of gelbstoff differed greatly in time and space. Secchi-disc transparencies indicated one attenuation depth (for light) of around 4 m and 7 m for the near-shore and the offshore waters, respectively, suggesting the use of only the surface chl-a value for validation of the satellite derived values for the pigment. The study also indicated that chl-a retrieval from the satellite image need not be corrected for the presence of pheophytin-a because of its low presence in the surface waters, but must be corrected for interference by the presence of high concentration of the gelbstoff.

4 illus, 2 tables, 15 ref

003277   Merkouriev S A;Sotchevanova N A (SPbFIZMIRAN, , Muchnov per,2, Box 188, St. Peterburg, 191 023, Russia) : Structure and evolution of the Carlsberg ridge: evidence for non-stationary spreading on old and modern spreading centres. Curr Sci 2003, 85(3), 334-8.

Results of magnetic and bathymetric data collected on board Russian vessels during the last decade have been presented. Analysis shows that since late Cretaceous the proto-Carlsberg Ridge (CR) was spreading at a faster rate, prior to India's collision with Eurasia. Since Eocene, the present CR is characterized by slow spreading. Results depict two discordant systems of linear magnetic anomalies. One corresponds with fast spreading with respect to latitude axis of the proto-ridge and the other with slow spreading with respect to modern axis of the CR, suggesting that the two spreading systems are asymmetric both relative to each other and relative to axial anomaly. Infers that during both these periods the structure and spreading on the CR was non-stationary.

8 illus, 23 ref

003276   Kulandaivelu E;Peshin S K (India Meteorological Department, , New Delhi-110 003) : Measurement of total ozone, D-UV radiation, Sulphur dioxide and Nitrogen dioxide with Brewer spectrophotometer at Maitri, Antarctica during 2000. Mausam 2003, 54(2), 505-10.

The latest state-of-art equipment called Brewer Ozone Spectrophotometer has been installed at Maitri, the permanent Indian Scientific Research Station, Antarctica in July 1999 to monitor total ozone, damaging part of ultra-violet radiation (D-UV), sulphur dioxide (SO₂) and nitrogen dioxide (NO₂). The depletion of ozone and its fluctuation were monitored day by day during Antarctica spring season (August-October). The data collected during the year 2000 are analysed. The values of total ozone and D-UV are compared in each month. The sudden increase or decrease of D-UV confirms further depletion or recovery of ozone in the successive days during the spring season. The measurements confirms the existence of 'Ozone hole' over Antarctica 2000. The measurements of SO₂ and NO₂ at Maitri show very low values.

6 illus, 6 ref

003275   Khole M;De u s (India Meteorological Dep, , Pune-411 005) : Study on north-east monsoon rainfall over India. Mausam 2003, 54(2), 419-26.

The North-East (NE) monsoon is one of the important components of Indian climate system. The aerial extent of NE monsoon generally extends over south-eastern peninsular India. The following five meteorological sub-divisions of India viz. coastal Andhra Pradesh, Rayalaseema, south interior Karnataka, Kerala and Tamil Nadu receive significant amount of rainfall during the NE monsoon. Using a long period data series 1875-1997, the variability of NE monsoon rainfall over south-eastern peninsula and whole India, is studied. The association of NE monsoon rainfall with El-Nino and La-Nina years is also analysed. It is observed that, the NE monsoon rainfall, over the south-eastern peninsular India is higher (lower) than normal, during El-Nino (La-nina) years. Also, the probability of NE monsoon rainfall over this region being excess or normal during El-Nino years is very high, 0.93.

6 illus, 4 tables, 20 ref

003274   Kazanci N;Oguzkurt D;Girgin S;Dugel M (Biology Dep, Hydrobiology Section, Hacettepe University, Science Faculty, Beytepe, Ankara, Turkey) : Distribution of benthic microinvertebrates in relation to physico-chemical properties in the Koycegiz-Dalyan estuarine channel system (meditarian sea, Turkey). Indian J Mar Sci 2003, 32(2), 141-6.

The Koycegiz-Dalyan Channel system is located between the ectogenicm, crenogenic and meromictic Lake Koycegiz and the Meditarian Sea. Twenty one species belonging to Bryozoa, Gastropoda, Bivalvia, Polychaeta and Crustacea were found at 6 sampling sites from the channel enterence of Lake Koycegiz to the Meditarian Sea. The faunal assemblage of sampling sites 3 and 4 along the Dalyan Channel had the highest species diversity because of the almost similar effects of Lake Koycegiz and the Meditarian Sea on the benthic assemblages and stable salinity compared to the other stations. The distribution of species in the channel system is mainly affected by salinity, temperature, phosphate, Mg²⁺, DO (dissolved oxygen) and SO₄^2-. Regular physical, chemical and biological monitoring of the channel system is recommended.

1 illus, 2 tables, 15 ref

003273   Karmalkar N R;Sarma P K (Dep of Geology, , University of Pune) : Characterization and origin of silicic and alkali-rich glasses in the upper mantle-derived spinel peridotite xenoliths from alkali basalts, deccan trap, Kutch, northwest India. Curr Sci 2003, 85(3), 386-92.

Petrological, textural and chemical characters of glasses found as discrete pockets in the spinel lherzolite xenoliths from Kutch region are discussed. These glasses are silica-saturated and alkali-rich in composition and display sharp contacts with the primary mineral assemblage of the spinel iherzolite. In contrast, the basaltic melt infiltrating the xenoliths exhibits reaction textures. These glass compositions have been compared with worldwide occurences. In the absence of any trace-element data, trace element data of the Cr-diopsides have been used from the same xenoliths and mechanisms of glass formation have been discussed. The glasss formation is attributed to the metasomatic fluids, mostly carbonatitic in composition, which is in agreement with previous work on these xenoliths. The metasomatism has occurred at a shallow level (7-12 kbar), slightly above the carbonatite stability field.

2 illus, 59 ref

003272   Kane R P (NO, Instituto Nacional de Pesquisas Espaciais, C.P. 515, Sao Jose dos Campos, 12201-970, SP, Brazil) : Periodicities in the frequency of Indian monsoonal cyclonic disturbances and storms. Mausam 2003, 54(2), 443-6.

When subjected to spectral analysis the series of the frequency of monsoon depressions and storms formed over the north Indian Ocean area (5<144N - 35<144N, 50<144E - 100<144E, Bay of Bengal and Arabian Sea taken together) for 1890 - 1999 indicated (a) a highly significant periodicity at T = ~40 years, and barely significant periodocotoes at T = 2-3 (QBO), 3.7, 4.6, 8.8 and 21.8 years of cyclonic disturbances, and (b) a highly significant periodicity at t = ~ 37 years, and significant periodicities at T = 2-3 (QBO), 11.4, and 15.4 years for cyclonic storms.

3 illus, 16 ref

003271   Kalsi S R;Kotal S D;Roy Bhowmik S K (India Meteorological Dep., , New Delhi-110 003) : Decaying nature of super cyclone of Orissa after landfall. Mausam 2003, 54(2), 393-6.

An attempt has been made to study the nature of decay of maximum wind speed of Orissa Super Cyclone (October 1999) after landfall. From the scanty observations that became available in respect of this cyclone, it is found that the maximum wind speed got reduced to a small but non zero value. An empirical equation relating wind sped with time after landfall has been developed. The value of decay constant (per hour) is found to be 0.0991. The technique is also tested to predict the wind speed after landfall for the very severe cyclonic storm of October 1999 which made landfall near Gopalpur in Orissa in the mid night of 17 October 1999. The wind speed estimated applying this technique is found to be consistent with the observations.

4 illus, 3 tables, 5 ref

003270   Jyothibabu R;Madhu N V;Murukesh N;Haridas P C;Nair K K C;Venugopal P (NO, National Institute of Oceanography, Regional Centre, ) : Intense blooms of Trichodesmium erythraeum (Cyanophyta) in the open waters along east coast of India. Indian J Mar Sci 2003, 32(2), 165-7.

The blooms of Trichodesmium erythraeum were observed during April 2001, in the open waters of Bay of Bengal and this is the first report from this region. The locations of the bloom were off Karaikkal (10°58′N, 81°50′E) and off south of Calcutta (19°44′N, 89°04′), both along east coast of India. Nutrients (nitrate, phosphate, silicate) concentration in the upper 30 m of the water column showed very low values. High-integrated primary production (Bloom 1- 2160 mgC m^-2 d^-1, earlier stages of the bloom. Very low NO₃-N concentrations, brownish yellow bloom colour, undisturbed patches and high primary production strongly suggested that the blooms were in the growth phase. Low mesozooplankton biomass was found in both locations and was dominated by copepods followed by chaetognaths.

^ssc2 illus, 2 tables, 8 ref

003269   Iyer S D;Ray D (NO, National Institute of Oceanography, Dona Paula, Goa-403 004) : Structure, tectonic and petrology of mid-oceanic ridges and the Indian scenario. Curr Sci 2003, 85(3), 277-89.

Existing information about the structure, tectonic and petrology of the 70,000 km long mid-oceanic ridges and focus on similar studies made of the Carlsberg-Central Indian Ridges have been examined and synthesized. The potential research areas and problems are also identified for the Indian ridge programme.

1 illus, 5 tables, 111 ref

003268   Iyer S D;Mukhopadhyay R;Drolia R K;Ray D (NO, National Institute of Oceanography, Dona Paula, Goa-403 004) : Mid-ocean ridges, inridge and the future. Curr Sci 2003, 85(3), 272-6.

Events that lead to the creation of a global scientific network for mid-oceanic ridge research, identify areas where Indian researchers could participate and built a case to support and gain momentum within the country for the young, emerging Inridge programme.

1 illus, 47 ref

003267   Islam M N;Islam A K M;Uyeda H (Biological Environment dep, Akita Prefectural University, Akita 010-0195, Japan) : Application of GMS-5 data in estimation of rainfall distribution. Mausam 2003, 54(2), 521-8.

The process of converting GMS-WEFAX imagery into binary data to calculate surface and cyclonic rain in and around Bangladesh was presented in this study. Satellite rainfall was calculated from GMS-5 data for the months of June-July 1996 using GMS Precipitation Index (GPI) and Convective Stratiform technique (CST). The rainfall calculated by GPI and CST was calibrated with that of calculated by rain gauge. On an average for June-July 1996, daily rainfall calculated by rain gauge, CST and GPI was 14 mm, 14.5 mm and 27.5 mm respectively. The regression equation was obtained for both GPI and CST analyses to calculate surface rain from satellite data. The CST method was found better than the GPI method in calculating surface rain. Then cyclonic rain was obtained using CST method on the event of a Cyclone occured 27-30 October 1999 over the Bay of Bengal.

5 illus, 12 ref

003266   Ingole B (Biological Oceanography Division, National Institute of Oceanography, Dona Paula, Goa-403 004) : Macrobenthic abundance in the vicinity of spreading ridge environment in central indian ocean. Curr Sci 2003, 85(3), 328-33.

Macrofaunal communities of the Central Indian Ocean were evaluated for their composition, distribution, abundance and biomass. The fauna comprised of 24 major groups belonging to 15 phyla. The density of macrofauna varied from 30 to 1430 ind.m^-2 (mean=376.39±345.97 SD; n = 56) and biomass varied from 0.11 to 12.75 g wet wt m^-2 (mean = 1.02±1.85 SD; n = 56). The results indicate that faunal density was negatively correlated with water depth (Y = -0.204x + 1204.5; r = -0.601; n = 56; P<60>0.001). Exponential increase in benthic standing stock (density and biomass) from eastern to western region (y = 2.3328x² - 328.8x + 11640; r = -0.712; n = 56; P<60>0.001; n = 56) suggests the direct relationship between the mid-ocean ridge environment and macrobenthic abundance. The recent discovery of hydrothermal activity in the Indian Ocean strongly suggests the possibility of many more such activities in the region and hence the mid-ocean ridge systems in the Indian Ocean make them a very attractive environment for benthic biological studies.

6 illus, 3 tables, 37 ref

003265   Drolia R K et al (NO, National Institute of Oceanography, Dona Paula, Goa-403 004) : Northern Central Indian Ridge : geology and tectonics of fracture zones-dominated spreading ridge segments. Curr Sci 2003, 85(3), 290-8.

Multi-beam and single-beam bathymetric, gravity and magnetic data, across seven ridge segments (length varying between 37 and 84 km), offset by six transform discontinuities (ranging in dislocation length between 48 and 344 km) of the Northern Central Indian Ridge (NCIR) were collected. Four Transform Faults (TF, viz. Sealark, Vityaz, Ehrlich and Vema) have been mapped in detail; while studies in geological, biological and water sampling were carried out at the last three transform faults. The ridge segments are characterized by along-axis depth variation: deepening at segment ends and shallowing at the centre. Both the ridge axis and TF areas are complex with intra- and inter-segmental morphotectonic and magnetic variations. Basalts collected from axial valley, Ridge-Transform Intersection (RTI) and from near-axis seamount, exhibit pillow and columnar structures. Samples from the RTI yielded ferro-managnese crust, nodules and intensely bioturbated calcareous sediments hosting nannoplanktons. The characteristics of the RTI, axial valley and transform and the presence of neo-volcanic zones along ridge-normal profiles suggest predominance of tectonomagmatic activities in the Vityaz and Vema regions. In the Sealark region, tectonic activities dominate.

4 illus, 1 table, 15 ref

003264   DeMets C;Royer J Y (Geology and Geophysics, University of Wisconsin-Madison, Madison, WI 53706, USA) : New high-resolution model for India-Capricorn motion since 20 Ma: implications for the chronology and magnitude of distributed crustal deformation in the Central Indian Basin. Curr Sci 2003, 85(3), 339-45.

More than 5000 crossings of magnetic anomalies and fracture zones along the Carlsberg and Central Indian ridges to examine whether the onset of widespread reverse faulting at ~8 Ma in the Central Indian Basin was accompanied by a significant change in India-Capricorn motion, whether the onset of this faulting represented the initiation of motion between these two plates, and whether the predicted shortening since 8 Ma agrees within uncertainities with fault-related shortening estimated from marine seismic profiles. The new-high resolution plate kinematic model, which specifies India-Capricorn finite and stage rotations at 20 distinct ages since 20 Ma, predicts that motion across the equatorial Indian Ocean was extremely slow from 17.4 Ma to 8 Ma, averaging less than 1mm yr^-1 everywhere along the plate boundary. A significant acceleration in the rate of angular rotation at 8 Ma ended the period of slow or possibly no motion and constitutes the first evidence for a significant change in India-Capricorn plate motion at this time. The change in motion at ~8 Ma coincided remarkably well with the onset of widespread reverse faulting in the Central Indian Basin, suggesting a cause-effect relationship. Despite evidence for the period of nearly negligible motion from 17.4 Ma to 8 Ma, motion of ~1-2 mm yr^-1 from 20.1 Ma to 17.4 Ma (chrons 6no-5D) is highly significant, thereby implying that the onset of faulting at ~ 8 Ma did not mark the time that India-Capricorn motion began. The total north-to-south shortening predicted by the 7.9 Ma finite rotation agrees within uncertainties with shortening estimated from faults imaged along marine seismic profiles, thereby indicating that most or all shortening of the upper crust since 8 Ma has been accomodated by faulting.

5 illus, 1 table, 28 ref

003263   Dash S K;Singh G P;Shekhar M S;Vernekar A D (NO, Indian Institute Technology, Hauz Khas, New Delhi) : Influence of eurasian snow depth anomaly on the Indian summer monsoon circulation. Mausam 2003, 54(2), 427-42.

The Historical Soviet Daily Snow Depth (HSDSD) version II data set has been used to examine the emprical relationship between the winter/spring snow depth anomaly over three different regions of Eurasia and Indian Summer Monsoon Rainfall(ISMR). HSDSD data show that difference in snow depth between two extreme years is most prominent over western Eurasia in the month of April and the inverse relationship between the spring snow depth anomaly and the following ISMR is very robust with correlation coefficient of -0.43 at 5% significant level. Examination of seasonal mean circulation pattern using NCEP?NCAR reanalysed data shows that low level atmospheric temperature difference between two extreme years of high and low western Eurasia snow depth in April can be as large as 10°C which gives rise to anomalous cyclonic circulation over the Caspian Sea and this may be responsible for affecting the monsoon circulation over India. Results also show that there is a complete phase reversal in the dipole structure of the upper tropospheric velocity potential anomaly from the deficient to excess ISMR irrespective of occurence of different phases of ENSO events or high/low Eurasian snow. However, during opposite phases of ENSO, the divergence center has east-west shiftas compared to the high Eurasian snow when the divergence centre shifts to the southeast over Australia.

12 illus, 3 tables, 26 ref

003262   Das H P;Kore P A (NO, , Meteorological Office, P A Kore) : Pattern of rainfall variability over dry farming zone of India and its agricultural implications. Mausam 2003, 54(2), 471-6.

Using suitable rainfall criteria, beginning of monsoon rains suitable for crop sowing, cessation of rainy season from agricultural point of view and the peak values of the rainfall, have been determined and their spatial distribution studied. Correlations of each of these parameters with time were computed to examine the possible trends. Association between number of rainy days and seasonal (monsoon) rainfall with time have also been attempted and discussed. With a view to determine coherence in rainfall pattern in the dry farming region (DFR), and index has been divised from its different sub-regions of the zone. Decadal analysis has also been done to see weather mean rainfall in a decade statistically differed from those in other decades.

7 illus, 8 ref

003261   Chattapadhyay N;Samui R P;Wadekar S N (India Meteorological Department, , Pune-411 005) : Weather based operational plant protection of leaf spot disease of groundnut. Mausam 2003, 54(2), 463-70.

Sensitivity of weather to the incidences of the leaf spot disease on groundnut was studied. Using data collected by PPQ <38> S during regular survey in different parts of the country it was observed that the disease occured more frequently in Andhra Pradesh, Karnataka, Gujarat and Maharashtra both in kharif and rabi seasons from 1988-1998. Weather systems causing drop in temperature associated with rainfall and overcast condition leading to increase inrelative humidity favoured incidence of the disease particularly when the crop was in pod formation to maturity stages. Decrease in maximum temperature ≤30°C and increase in morning and afternoon relative humidity ≥80% and 60∃ respectively under cloudy condition (2-8 okta) associated with rainfall were found to be cogenial for the development of the disease in moderate to severe intesities. This weather based information along with field observations on incidence of this disease could be used to forewarn the incidence of the leaf spot disease on groundnut for taking plant protection measures at appropriate time through Agromet Advisory Service.

3 illus, 1 table, 11 ref

003260   Chakraborty B;Lourenco E;Kodagali V;Baracho J (NO, National Institute of Oceanography, Dona Paula, Goa-403 004) : Application of artificial neural networks to segmentation and classification of topographic profiles of ridge-flank seafloor. Curr Sci 2003, 85(3), 306-12.

Artificial Neural Networks (ANN) for seafloor topographic data segmentation and roughness classification has been utilized using the multibeam Hydrosweep system (installed onboard ocean research vessel Sagar Kanya) data. Bathymetric profiles from three directions; central (beam 30), port side (beam 10) and starboard side (beam 50), were acquired from the ridge flank and rift valley areas of the Carlsberg Ridge and plain areas of the Central Indian Basin. Self-Organizing Map (SOM)-an ANN architecture employing unsupervised training is used for segmentation of the depth data. This neural architecture is successful in segmenting nonstationary profiles into stationary type before being used for classification. The number of segmented profiles is highest for the rift valley areas whereas for plain area profiles no segmentation is required. Another ANN architecture using supervised training - the Multi-Layer Perceptron (MLP) is applied for the classification of the segmented profiles in two steps. The MLP network was trained using simulated bathymetric profiles of known power spectral (correlation) parameterβ, which has been used to classify the multibeam-Hydrosweep depth data. Another parameter S (amplitude parameter) is also being computed for classification. Estimated β and S values of the segmented profiles indicate the sedimentary origin of the plain area. Whereas the estimated parameters for ridge flank and rift values indicate that these areas have volcanic or tectonic origin.

6 illus, 18 ref

003259   Bidyananda M;Deomurari M P;Goswami J N (Planetary and Geosciences Division, Physical Research Laboratory, , Navrangpura, Ahmedabad-380 009) : <. Curr Sci 2003, 85(10), 1482-5.

²⁰⁷Pb/²⁰⁶Pb ages of individual zircon grains from metasediments and tonalite trondhjemitic and granitic gneisses in the Nuggihalli schist belt, Dharwar craton are determined by an ion microprobe. Zircons identified in a metasedimentary rock have ages up to <126>3.2 Ga, suggesting an upper limit age of 3.3 Ga for the onset of sedimentation in this region. The ages of the gneissic protoliths are <126>3.1 Ga and they appear to be nearly contemporaneous with the metasedimentary protholiths. Our data and those reported previously are indicative of multiple emplacement of the gneissic precursors, and suggest an episodic evolution of the Dharwar craton over an extended period during the early Archean.

1 table, 17 ref

003258   Bhupathy S;Karunakaran R (NO, Salim Ali Centre for Ornithology and Natural History (SACON), Anaikatti (PO), Coimbatore-641 108, Tamil Nadu) : Conservation of olive ridely sea turtle Lepidochelys olivacea (Reptilia/Chelonia) along the Nagapattinam coast, southeast coast of India. Indian J Mar Sci 2003, 32(2), 168-71.

Nesting and mortality of Lepidochelys olivacea (Eschscholtz, 1829) was studied in 50 km beach stretch along the Nagapattinam coast during December 2000 to May 2001. Lepidochelys olivacea was common constituting 97.1% of turtles recorded. This species emerged from sea for nesting during December and continued till April. The nesting of Lepidochelys olivacea was sporadic and the peak was observed in the second fortnight of February. The poor nesting (20 nests/km) in the area could be due to high adult mortality (12 % females) due to incidental catch in the gill nets, and nest predation (<62>90%) by human. The Nagapattinam coast will not sustain the nesting population of Lepidochelys olivacea longer, if immediate conservation measures are not undertaken.

^ssc2 illus, 15 ref

003257   Bhide U V;Puranik P V;Mujumdar V R;Kulkarni A A;Kripalani R H (NO, , ) : Development of monsoon breaks due to heat source over northwest India. Mausam 2003, 54(2), 377-84.

A synoptic climatological analysis of pentad rainfall anomalies for 52 blocks over India for southwest monsoon season for the years 1901 to 1980 has been carried out to identify events of anomalous heavy rainfall over the western part of the monsoon trough area and study the change in rainfall distribution over central parts of the country in subsequent three pentads. This analysis is based on the results of a diagnostic study by Bhide et al. (1997) which showed that the events of development of diabatic heat sources due to convective heavy rainfall over the western part of the monsoon trough area were followed by the occurrence of a weak or break phase during monsoon 1979. An event of positive pentad rainfall anomaly (SA) for a test area TA on the western part of the monsoon trough is considered as a basic synoptic event. SA is categorised into five classes C1 to C5 having ranges between -1 and 9. The change in rainfall anomalies for subsequent three pentads is studied. The pattern of rainfall anomalies for class C5, having the largest values of SA indicates development of a break phase over India and confirms the earlier observation for monsoon 1979. The development of a weak phase is indicated for class C4.

5 illus, 2 tables, 6 ref