023875   Chandrasekhar D V;Singh B;Firozishah M;Mishra D C (NO, National Geophysical Research Institute, Hyderabad-500 007, Email: go4sekhar@yahoo.com) : Analysis of gravity and magnetic anomalies of Kachch rift basin, India and its comparison with the new Madrid seismic zone, USA. Curr Sci 2005, 88(10), 1601-8.

The M_w 7.6 Bhuj earthquake of 26 January 2001 is in many ways considered similar to New Madrid earthquakes of 1811-12 in the central United States. Analysis of gravity and magnetic anomalies constraining with the seismic and magneto-telluric studies suggests faulted basement and a zone of high magnetic and denser material (Deccan Trap affinity) in the Bhuj epiccentral region and founc analogous to the Gabbroic intrusion along Commerce Geophysical lineament of New Madrid seismic zone. Isostatic regional gravity anomaly map of Kachchh presents two gravity lows within the Kachchh rift basin, indicating mass deficiency due to crustal thickening up to 8 km, similar to one in Mississippi embayment by Missouri batholith, intersecting the Reelfoot rift and the two might be intimately related to seismicity in respective regions. Seismicity in Kachchh, though, might be due to stress concentration due to coupled force system, i.e. the horizontal tectonic stresses due to movement of the Indian plant and intraplate stresses induced by crustal heterogeneities; however, the source of gravity lows could intimately be related to earthquake activity in Kachachh, as widely inferred for Missouri gravity in Kachchh, as widely inferred for Missouri gravity low in case of New Madrid seismic zone.

8 illus, 36 ref

023874   Biswas S K (Earth Science Dep, Indian Institute of Technology Bombay, Maumbi-400 076) : A review of structure and tectonics of Kutch basin, western India, with special reference to earthquakes. Curr Sci 2005, 88(10), 1592-1600.

The Kutch basin is a western margin pericratonic rift basin of India. Nagar Parkar uplift in the north and kathiawar uplift (Saurashtra horst) in the sourth respectively along Nagar Parkar and North Kathiawar faults selimit the E-W rift. The Kutch rift was initiated during the Late Triassic break up of the Gondwanaland by th ereactivation of primordial faultsin the Precambrian Delhi fold belt. The rifting was aborted during Late Cretaceous pre-collision stage of the Indian plate. During post-collision compressive regime of the Indian plate, the Kutch rift basin became a shear zone with strike-slip movements along sub-parallel rift faults. The Kutch Mainland Fault along the rift axis became the active principal fault. Presently, this right lateral strike-slip fault is overstepped by the South Wagad Fault in the eastern part of the basin. The overstep zone between the two wrench faults is a convergent transfer zone undergoing transpressional stress in the strained eastern part of the basin. The epicenters of two big earthquakes as well as the aftershock hypocenters of Bhuj earthquake are locaed within this zone. The study of the intrusive rocks, rift geometry and seismic tomography indicates presence of a large ultramafic body in th elower crust. An overview of the structural and tectonic evolution of the basin is discussed in the context of earthquakes. Based on structural and detailed depth-wise analysis of aftershock data, a conceptual domino-listric model of Kutch rift ...

6 illus, 28 ref

023873   Bilham R;Ambraseys N (CIRES and Geological Sciences, University of Colorado Boulder 80309-0399, USA, , Email: bilham@colorado.edu) : Apparent Himalayan slip deficit from the summation of seismic moments for Himalayan earthquakes, 1500-2000. Curr Sci 2005, 88(10), 1658-63.

Re-evaluated estimates of the magnitudes of Himalayan earthquakes since 1500 (ref. 1) permit a measure of the convergence rate between India and Tibet for the past five centuries. Averaged over the entire Himalya, the calculated rate (<60>5 mm/yr) is less than one third of the donvergence rate observed from GPS measurements in the past decade (18 mm/yr). The missing slip is equivalent to four M_w <62> 8.5 earthquakes, events that are unlikely to have escaped note in the historical written record. The absence of repeated rupture anywhere in the Himalaya permits several explanations for the missing slip, ranging from the extreme view that large earthquakes are in out future, to less hazardous interpretations, related to flaws in the historical data on Himalayan earthquakes.

4 illus, 1 table, 32 ref

023872   Anilkumar N;Dash M K;Luis A J;Ramesh Babu V; Somayajulu Y K;Sudhakar M;Pandey P C (National Centre for Antarctic and Occan Research, , Headland Sada, Goa-403 804, Email: anil@acaor.org) : Oceanic fronts along 45°E across antarctic Circumpolar current during austral summer 2004. Curr Sci 2005, 88(10), 1669-73.

A pilot experdition was launched to monitor the oceanic fronts in the southwestern sector of the Indian Ocean during January-Febrary 2004. Major fronts along 45°E between 40 and 56°S were delineated and their spatial variations during 6-17 February have been compared with earlier studies. The Agulhas Return Front (ARF) has been identifiecd between 40°15' and 41°15'S with a change in temperature from 19 to 17°C and a change in salinity from 35.54 to 35.39% at the surface. The position of Subtropical Front (STF) was observed between 41°15' and 42°15'S, with a rapid decrease in surface temperature from 17 to 10.6°C and salinity from 35.35 to 34.05%. The Subantarctic Front has been located between latitudes 42°30' and 47°S, with a change in surface temperature from 9.7 to 6.3°C and change in surface salinity from 34.0 to 33.85%. One of the significant findings here compared to previous studies is the identification of ARF and STF with almost equal width of ~110 km. In addition, the Surface Polar Front and the Subsurface Polar Front were also identified between 48 and 52°S. Temperature minimum layer has been located between 49 and 56°S and extends from 150 to 200 m....

5 illus, 1 table, 18 ref

023871   Agarwal P K;Pandey O P;Chetty T R K (National Geophysical Research Institute, , Hyderabad-500 007) : Aeromagnetic anomalies, lineaments and seismicity in Koyna-Warna Region. J Indian Geophys Union 2004, 8(4), 229-42.

Study reveals a prominent 300-400 m local Quaternary upliftment over the already uplifting block of western margin. These uplifted regions, situated on either side of the Koyna river faulted/subsided block, appear to be a block-like structure. They are bounded on either side by two faults, one originating in the NNE-SSW and the other in the NNW-SSE direction. The NNE-SSW trending fault falls in the line of Koyna reservoir. These two faults are intersected in the middle by two parallel E-W trending faults, which correspond well to the course of the Koyna River. These intersecting faults result in the formation of two triple junctions, one situated south of the Koyna dam and the other near Ural-Nisre region lying to the east of Koyna. Between the Koyna-Warna reservoirs, several intersecting lineaments are observed. A good correlation between the lineaments derived from the satellite imagery and from aeromagnetics can be seen. The intersection of the magnetic lineaments along Warna region with NNE-SSW trending fault suggests possible development of a new system of faults between Koyna and Warna reservoirs.

12 illus, 20 ref

023018   Yerneni S;Phadke S;Bhardwaj D;Chakraborty S; Rastogi R (NO, , Cray-Hinditron, 203-A, Hemkunt Tower, 98, Nehra Place, New Delhi-110 019, Email: sudhakar@hinditron.com) : Imaging subsurface geology with seismic migration on a computing cluster. Curr Sci 2005, 88(3), 468-74.

In petroleum exploration, migration is one of the most compute-intensive steps in the seismic data processing sequence. It accurately images the reflected and diffracted emergy and aids in delineating the detailed structural features of the underground geological formations. Migration techniques are highly compute and input/output (L/O) intensive, and therefore require high-performance computers. Parallel computers based upon clustering technology provide a cost-effective solution as most of the seismic migration alorithms are inherently parallel in several domains. Parellelism is achieved by decomposing the seismic data into frequency slices, planewave volumes or simply spatial cubes. Design and implementation of parallel alogrithms for a cluster of workstations is quite straightforward. Large data volume necessitates the optimization of I/O, to and from mass storage devices. Computational demands of several seismic migration methods has been studied and showed their implementation on a cluster of workstations. Efficiency and speed is achieved by code restructuring, parallel I/O, and overlapping computations with communication. Performance of migration algorithms is demonstrated on PARAM series of parallel computers.

6 illus, 17 ref

023017   Wavde P N;Patel N T;Dakore H G (NO, Rajiv Gandhi Coll, Mudkhed, Dist Nanded-431 602) : Assessment of fluoride and iodide content in groundwater of Malegaon village of Nanded district, Maharashtra. Bioinfolet 2005, 2(2), 119-21.

Groundwater quality in Malegaon Village has been studied with special reference to the presence of fluoride and iodide along with other chemical parameters for 1 year during June-2002 to May-2003. The fluoride content was below permissible limit. Iodide content was also found to be within the permissible limit prescribed by WHO. The maximum concentration of fluoride and iodide was observed during monsoon while minimum during summer season. The values of other parameters were also found within the permissible limits prescribed for drinking water.

1 table, 14 ref

023016   Vijay Kumar;Luick J L (Natn Inst of Hydrology, Western Himalayan Regional Cent, Opposite Military Hosptial, Satwari, Jammu Cantt-180 003) : Effect of Various parameters on the size of freshwater lens in home island. J appl Hydrol 2004, 17(1), 69-78.

The density dependent groundwater flow and solute transport model SUTRA (Saturated-Unsaturated Transport) is employed to analyse the effects of various controls on the size of the freshwater lens in an atoll island, namely Home Island, groundwater systems. Home Island is one of the two main inhabited islands of the Cocos (Keeling) Islands. The effect of rainfall recharge rate, permeability, porosity, and dispersivity has been studied. It was found that the permeability, dispersivity and the rainfall recharge rate effects the size of the freshwater lens to a large extent, whereas, the effect of porosity is small. The chosen time step effect the sturcture of the transition zone in the form of large fluctuations in the salinity concentration contours.

6 illus, 3 tables, 8 ref

023015   Vara Prasad G S;Guru Rajesh K;Srinivasulu S; Sambasiva Rao T (Geol Dep, S.V. Univ, Tirupati-517 502) : Drainage morphometric analysis of the Valagalamanda river basin Chittoor district, A.P.. J appl Hydrol 2004, 17(1), 18-23.

The Valagalamanda river rises from the Valikonda hills and flows eastwards for about 25 KM and joins Swarnamukhi river at Cheemuru Village. The Valagalamanda sub-basin (VSB) covers an area of 284.06 Sq. km. The drainage pattern is dendritic. It is a 6th order basin and elongated in East-West direction. The bifurcation ratio 3.8 and hypsometric analysis indicate the mature stage of development. The stream length ratio is 0.87, area ratio, 4.04, mean drainage density 2.41 Km / Sq. Km and stream frequency of the basin 2.78 per Sq. Km. The general slope of the basin is from West to East. The low slope regions are potential zones for ground water accumulation.

3 illus, 3 tables, 13 ref

023014   Vajrappa H C;Rajadhan Singh N (Geol Dep, Bangalore Univ, Bangalore-560 056) : Factor analysis of hydrochemical data of Suvarnamukhi sub-basin of Arkavathi river, Bangalore district, Karnataka. J appl Hydrol 2004, 17(1), 32-7.

Statistical factor analysis (FA) technique have been applied to hydrochemical data of 95 bore well water samples from Suvarnamukhi sub-basin. FA technique identified three factors, which account for 74.82% of the major ion variations observed in the sub-basin, namely, TDS, carbonate and bicarbonate. The comparison between unrotated and rotated communality values and rotated factor matrix led to similar interpretations. Spatial variations of factor scores have been contoured and found that it could be directly correlated with the lithological units.

5 illus, 4 tables, 7 ref

023013   Upadhyay R;Ram-Awatar;Kar R K;Sinha A K (Geol Dep, Kumaun Univ, Nainital-263 002, Email: rajeev_up@yahoo.com) : First record of middle-late jurassic palynomorphs from the Lamayuru complex, Indus suture zone, Ladakh, India. Curr Sci 2005, 88(6), 980-6.

Authors reports here Middle-Late Jurassic palynomorphs bearing sediments from the Lamayuru Complex, exposed along the Indus-Tsangpo Suture Zone in Ladakh. Apart from addition of new data towards understanding the geodynamics of the India-Asia collision zone, this will be helpful in understanding the formation of the slope-dep marine passive margin turbidites basin along the Indus Suture Zone, its palaeogeography and the processes of sedimentation and tectonics during subduction of the Indian plate beneath the Asian plate. The presently recorded Middle-Late Jurassic palynomorphs from the Lamayuru Complex also help to further strengthen viewpoint that the Permian and Mesozoic palynomorphs bearing sediments were reworked from the Zanskar-Lamayuru Complex Taethyan realm and transported through the Lamayuru Complex to the Nindam basin during ongoing geodynamic processes operative within the India-Asia trench-forearc subduction complex between Cretaceous-Palaeocene time span.

5 illus, 34 ref

023012   Swain J;Singh M K;Vijayakumar D;Chanchal De; Venkitachalam N R (NO, Naval Phys and Oceanographic Laboratory, Kochi) : Wave hindcast for the Indian ocean region covering the period of ARMEX-I (June-August 2002). Mausam 2005, 56(1), 263-8.

Wave hindcast has been carried out for the Indian Ocean (30° -120° E, 30° S - 30° N) region covering ARMEX, PHASE-I observational programme (June-August 2002). The analysed wind fields at six hourly intervals provided by National Centre for Medium Range Weather Forecast (NCMRWF), New Delhi is used to drive the third generation wave model "WAM" (1.5° x 1.5° resolution). The primary objectives of this hindcast, is to provide the sea-state information for the period of ARMEX which would help in research applications and to implement WAM operationally for the Indian Ocean to meet various requirements in future. The model was earlier validated using the ship Borne Wave Recorder (SBWR) data collected on board INS Sagardhwani, the visual estimates reported in the Indian Daily Weather Report (IDWR) published by the India Meteorological Department (IMD) and time-series buoy measurements of National Institute of Ocean Technology (NIOT). The model outputs are compared with the available buoy data of NIOT. The comparisons between the hindcast wave parameters and measurements reveal that the model could predict wave heights with errors ranging from ±12% to ±20%.

7 illus, 9 ref

023011   Swain J;Chanchal De;Abdul Salam K A; Radhakrishnan V G (NO, Naval Phys Oceanographic Laboratory, Kochi-682 021) : Observations of internal wave oscillations in the upper thermocline based on CTD-yoyo measurements during ARMEX-I. Mausam 2005, 56(1), 275-80.

A CTD yoyo experiment was conducted onboard ORV Sagar Kanya (SK-179) during the second cruise of ARMEX Phase-I to observe the extent of internal wave oscillations which induce sound speed fluctuations along their propagation path. The Mini CTD of Sensor data was attached with the Sea-Bird CTD available onboard SK. Both the systems were continuously lowered and hauled up (yoyo) within the upper thermocline, between 45 and 205 m of the water column at a deep water location (15° 23.12' N and 72° 10.55' E) while the ship was allowed to drift. There were total 36 profiles (down cast and up cast) collected within a period of 2 hours and 10 minutes. The observations made by Mini CTD and Sea-Bird CTD were interpolated in depth (50 to 200 m at 1m interval) and time (3.6 minutes - duration of each cast) for comparison as they have different accuracies. The profiles collected during the start of the yoyo and on completion clearly revealed a well defined mixed layer (nearly 43 m) and its temperature remained practically same. The isotherms during the time-series clearly revealed internal wave oscillations of height and period ranging from 2 to 4 m and 18 to 40 minutes respectively excluding the higher frequencies. The upward and downward movements of 2 to 20 m along the depth/vertical were attributed to well known tidal internal waves.

7 illus, 2 tables, 9 ref

023010   Sukumaran C;Rajitha Madhu Priya T;Dharmaraj T;Murthy B S;Sivaramakrishnan S (NO, Indian Inst of Trop Meterology, Pune-411 008) : Variation of water vapor and CO₂ at Goa during ARMEX phase-I and II. Mausam 2005, 56(1), 213-20.

Mass density fluctuations of CO₂ and water vapor were measured at 5 m above ground level (agl) on a 9 m high micrometeorological tower in the premises of the National Centre for Antarctic and Ocean Research (NCAOR) Vasco da Gama, Goa, as a part of the Arabian Sea Monsoon Experiment (ARMEX). Open path Infra Red (IR) Hygrometer (LI - 7500) was used to collect samples at a rate of 10 per second. Hourly averaged values of CO₂ and water vapor were used to study the diurnal variation for 3 days every month in ARMEX phase-I (June-September 7002) arid phase-II (March, April, May, June 2003).

5 illus, 7 ref

023009   Stephen J;Singh S B;Yedekar D B (DRS Grp, Natn Geophys Res Inst, Hyderabad-500 007, Email: Jimmy@ngri.res.in) : Evidence of elastic strength variation across the central Indian tectonic zone: a support to the proterozoic collisonal tectonics. Curr Sci 2005, 89(1), 190-4.

Isostatic models of the lithosphere generally consider the topographic loads supported in part by stresses within the lithosphere, and in part by forces associated with the deflection of density interfaces. Information on the mechanical properties of the lithosphere is generally derived from the gravity and topography transfer function relationships. In the study, mapping for a posible strength variation across the Central Indian Tectonic Zone (CITZ), using coherence method extended to two-dimensional fields. Estimations yielded relatively higher effective elastic thickness values for the North Indian Block, representing a stronger lithosphere, than the South Indian Block. This strength variation provides significant support to the Proterozoic collisional tectonics across the CITZ.

3 illus, 39 ref

023008   Srinivasan K;Ganju A;Sharma S S (Snow and Avalanche Study Establishment Res and Dev Cent, , Chandigarh-160 036, Email: ksv66@hotmail.com) : Usefulness of mesoscale weather forecast for avalanche forecasting. Curr Sci 2005, 88(6), 921-6.

Avalanche occurrence is a result of the structural collapse of snow cover in the upper reaches of mountainous regions. The collapse may occur either by internal factors related to snow metamorphism or exernal factors like excessive loading of the snow cover due to snow precipitation, falling of boulders and snow lumps, cornice collapse, explosive waves or seismic activities. Thus to predict an avalanche accurately, an avalanche forcaster is required to keep a continuous record of the weather elements prevailing in the higher reaches which contributes to metamorphism and also the excessive loading of the snow cover due to snow precipitation, cornice formation and its collapse, wind transportation, cornice formation and its collapse, wind transportation, etc. The information available of the above factors on the synoptic scale, though sufficient for assessment of avaoanche danger on a larger scale for a period specific forecast for a general area, is however not sufficient for site-specific and time-specific forecast of a avalanche. This, to a certain extent, can be achieved through mesoscale modelling of various weather parameters using a high-end workstation. The paper describes the genesis of avalanche formation, and the conventional techniques of avalanche forecast in vogue in most of the countries experiencing snow precipitation and avalanches. The paper also brings out how mesoscale modelling of weather parameters can assist in site- and time-specific forecast of an avala

10 illus, 2 tables, 5 ref

023007   Srinivasan G;Nair S (Sci and Technol Dep, , New Delhi-110 016) : Daily rainfall characteristics from a high density rain gauge network. Curr Sci 2005, 88(6), 942-6.

Enhanced observational information on the spatial distribution of rainfall, at a finer resolution, is vital for evaluation of mesoscale models. The study examines the daily rainfall data from a high-density mesoscale rain gauge network consisting of 25 stations within a hundred sq. km. area, during the south west monsoon season (June-September) for the period 1996-2000. The rainfalls reported are from lake catchments along the Western Ghats, falling in the district of Raigad and other urban locations in and around Mumbai. Using this data-set, an attempt has been made to examine the spatial distribution of heavy rainfall events. Poor correlations between stations indicate that they cannot be pooled together during spatial averaging for representing rainfall over the area. Heavy rainfall events contributed largest rainfall amounts at the foothills of the ghats and the least for sites on the Western ghats at higher altitudes. The results suggest that different controls modulate the synoptic situations to produce a controls modulate the synoptic situations to produce a spectrum of spatial and temporal precipitation variability on local scales, which would require further observational and modeling efforts to understand and predict.

5 illus, 2 tables, 3 ref

023006   Srinivasa Gowd S (Environemntal Geochemistry Grp, Natn Geophys Res Inst (NGRI), Hyderabad-500 007) : Morphometric analysis of Peddavanka Basin, Anantapur district, Andhra Pradesh, India. J appl Hydrol 2004, 17(1), 1-8.

Morphometric analysis and their relative parameters have been quantitatively carried out for the Peddavanka basin, Anantapur district, Andhra Pradesh, India. The quantitative analyses of the morphometric characteristics of the basin include Stream order, Stream length, Bifurcation ratio, Drainage density. Drainage frequency, Relief ratio. Elongation ratio and Circularity ratio. The foregoing analysis clearly indicates some relations among the various attributes of the morphometric aspects of the basin and helps to understand their role in sculpturing the surface of the region.

4 illus, 4 tables, 6 ref

023005   Srinivas C V;Venkatesan R;Bagavath Singh a (Radiological Saf Div, Indira Gandhi Cent for Atom Res, Kalpakkam-603 102, Email: cvsri@igcar.ernet.in) : A numerical study of the influence of synoptic flow on coastal meso-scale circulations on the East and West coast of India. Mausam 2005, 56(1), 73-82.

The effect of synoptic flow on the coastal boundary layer and land sea breeze circulation on the west and east coasts has been investigated by a numerical simulation using PSU/NCAR-MM5 mesoscale model. A study on 24th May 2003 during ARMEX observation period shows occurrence of land-sea breeze circulation and formation of thermal internal boundary layer (TIBL) on both the coastal regions in the daytime but of some differences. An early development and accelerated propagation of sea breeze circulation is noticed on the west coast compared to the east coast under the influence of the prevailing southwesterly flow. The strength of the sea breeze is more on the west coast. The mixing heights during daytime in the coastal regions are reduced by the formation of TIBL. The horizontal extent of TIBL is very less (24 km) on the west coast under the complex topographic effect. The sea breeze frontal activity is more intensive on the east coast with vertical velocity of the order of 2-4 m/sec by the retarding influence of southwesterly synoptic flow.

12 illus, 12 ref

023004   Sridhar A;Patidar A (NO, , , Email: alpasridhar@rediffmail.com) : Ground penetrating radar studies of a point-bar in the Mahi river basin, Gujarat. Curr Sci 2005, 89(1), 183-9.

Communication is an attempt to study a point-bar deposit using round Penetrating Radar (GPR). The vertical as well as lateral variations in the lithofacies and the continuity of the bounding surfaces are delineated using the trench and GPR profiles. The basal part of the point-bar at Angad indicates deposition under a near-continuous flow with minor changes in velocity and direction giving rise to fining upward planar cross-stratified sand facies typical of a point-bar sequence. However, the sediments in the upper part show high degree of lateral and vertical heterogeneity in terms of facies development and is inferred to have resulted due to deposition by high stagre flood events associated with cyclonic storms and the gradual waning flow. The lithofacies assemblage and morphology of the bar from head to tail-end suggest that the bar deposition is mainly controlled by downstream accretion. The sediment sequences of the point-bar exposed in trenched and on GPR profiles are helpful in deciphering the hydrologic regime of the depositing river channel.

7 illus, 28 ref

023003   Singh O P;Hatwar H R (Indian Meteorological Dep, , New Delhi-110 003, Email: op_singh54@yahoo.com) : Response of sea state to the monsoon onset. Mausam 2005, 56(1), 59-64.

Utilizing the buoy meteorological data of Arabian Sea collected during the onset phase of ARMEX an attempt has been made to examine the influence of monsoon onset 2003 on the surface parameters. The peaking and collapse of warm pool during monsoon onset 2003 has been compared with the normal peaking and collapse conditions and it has been found that the collapse of warm pool during the onset of 2003 monsoon was very gradual. As a matter of fact the evaporative cooling in the warm pool region was quite subdued during 2003 monsoon onset which shows that the sudden collapse of warm pool should be expected to occur only when onset vortex is formed which did not happen during 2003. The roughness of sea (wave height) increased over the southeastern Arabian Sea about 2-3 days before the monsoon onset showing that the swells are reliable precursors of monsoon onset. There was a steep fall in SLP throughout the eastern Arabian Sea (8° - 20°N) about a week before the monsoon onset over Kerala on 8 June. All buoys from DS7 to SW1 registered this type of SLP change. After the sudden fall on 1 June the SLPs over the eastern Arabian Sea remained almost steady and unimpacted by the monsoon onset on 8 June or subsequent advance along the west coast.

6 illus, 6 ref

023002   Sikka D R (NO, , 40, Mausam Vihar, New Delhi-110 051, Email: drsikka@yahoo.com) : From the International Indian Ocean Expedition (IIOE) to the Arabian Sea monsoon experiment (ARMEX) - four decades of major advances in monsoon meteorology. Mausam 2005, 56(1), 19-36.

Vast amount of researches on describing understanding, modelling and prediction of monsoon have taken place in the last 50 years or so as new observational and computational technologies have been introduced. Several field observational programs using state of the art sea-land and space-based observational systems have been undertaken nationally and internationally in the last 4 decades beginning with the IIOE (1963-1965) and culminating in the ARMEX (2002, 2003) which have given new challenges to monsoon-related research. The paper provides salient features of the research on the Indian monsoon accomplished during the four decades (1963-2003) using observational and modelling studies and the discusses new challenges which lie ahead for its further improved understanding and prediction.

231 ref

023001   Shivhare R P (Air HQ (Vaya Bhawan), , New Delhi-110 011, Email: rpshivhare@yahoo.com) : Episodes of aircraft icing during ARMEX phase-I. Mausam 2005, 56(1), 83-8.

In-flight icing is one of the major weather hazards to aviation. During ARMEX Phase-1, there were three occasions out of twenty sorties when in-flight icing was encountered while flying over Arabian Sea in the Russian made transport aircraft AN-32. The icing episodes were studied vis-a-vis the prevailing synoptic situations and the convective cloud features. It was found that the aircraft was flying in the vicinity of convective cells associated with considerable horizontal wind shear. The temperature at me flight level was observed to vary from -6 to -8° C. The presence of large amount of supercooled water droplets can be assumed to be associated with the active and intense convection that is usually found under the active monsoon conditions.

6 illus, 3 tables, 1 ref

023000   Shenoi S C;Shankar D;Gopalakrishna V V;Durand F (Natn Inst of Oceanography, , Dona Paula, Goa-403 004, Email: shenoi@darya.nio.org) : Role of ocean in the genesis and annihilation of the core of the warm pool in the southeastern Arabian Sea. Mausam 2005, 56(1), 147-60.

The earlier hypothsis stated in the ARMEX (Arabian Sea Monsoon Experiment) Science Plan, that the ocean plays an important, but passive, role in the genesis of the core of warm pool in the southeastern Arabian Sea (SEAS) is examined in the light of new data collected during Phase II of ARMEX. The new evidence confirms that the ocean plays an important role. This paper summarises the results based on these data, which show that the remotely forced ocean dynamics plays an active, not passive, role-not only in the genesis of the core of the warm pool in the SEAS, but also triggers the collapse of the warm pool.

15 illus, 41 ref

022999   Satyanarayana K V V (Geophysics Dep, Andhra Univ, Visakhapatnam) : Geological and geo-electrical characteristics of the Sitanagaram area, Vizianagaram district, Andhra Pradesh. J appl Hydrol 2004, 17(1), 87-100.

Significance of groundwater exploration is gaining importance day by day due to frequent failures of monsoon. So delineation of sub-soil andh and bedrock charactristic near Sitanagaram village.Vizianagaram district was done in a systematic way. The study area has as areal extent of 10 sq kms. The area is underlain by graniticgneissic rocks of Archaean age and alluvium of recent age. The groundwater is exploited by means of filter point wells in alluvium and dug wells in granitic greesses. Thirty seven geoeleetrical sounds were done in a grid pattern in the entire study area to ascertain bed rock profile.

9 illus, 1 table, 9 ref

022998   Sam N V;Mohanty U C;Kaur P S (Cent for Atmospheric Sci, Indian Inst of Technol, New Delhi-110 016) : Conserved variable and observational analysis over the West coast of India during ARMEX-2002. Mausam 2005, 56(1), 201-12.

The Arabian Sea Monsoon Experiment (ARMEX) addresses monsoon and associated convective activity, laying emphasis on the monsoon onset processes and intense rainfall events over the west coast of India. The prime objective of this paper is to study the variation observed in the surface and upper air parameters obtained over the west-coast of India during ARMEX. Conserved Variable Analyses (CVA) of viz., potential temperature, virtual potential temperature, saturation equivalent potential temperature and specific humidity etc. were also carried out at every point up to 3 km from the surface to cover the boundary layer over convectively active and suppressed regimes along the west-coast of India during this period. Analyses of the surface parameters such as sea-surface temperature (SST), air temperature, wind speed and moisture along the ORV Sagar Kanya (ORVSK) cruise track were carried out. Similar analysis was also carried along a few of the west-coast land stations viz. Vijaydurg, Karvar, Honavar and Goa. The structure of the boundary layer was found to be varying depending on the various factors that influence lower atmosphere and the general trend being a pronounced increase in the boundary layer height during an active convection process just before the heavy rainfall event.

8 illus, 10 ref

022997   Roy S S;Roy Bhowmik S K (NO, , , Email: sonasenroy@yahoo.com) : Analysis of thermodynamics of the atmosphere over northwest India during the passage of a western disturbance as revealed by model analysis field. Curr Sci 2005, 88(6), 947-51.

The paper analyses the vertical structure of the atmosphere over Delhi as representative of atmospheric conditions over northwest India during the passage of a western disturbance (WD) during January 2002. In association with this WD, Delhi received the first and most abundant rainfall of the winter season on 15 January. The paper explores the thermodynamics of the atmosphere computing CAPE, CINE, moist static energy and other moisture parameters of Delhi based on model analysis fields, of India Meteorological Department. The vertical vorticity profiles for this station have also been calculated. A clear increase in the value of CAPE and decrease in the value of CINE is noticed on the days of occurrence of rainfall over the station (15-18 January). The surface moist static energy curve on the other hand, shows a significant increase in value two days prior to the occurrence of rainfall over the station. The precipitable water content profile of the column of the atmosphere above the station is seen to closely follow the rainfall pattern associated with the system. The model analysis field for moisture anomalies reveals fingers of increased moisture in the upper troposphere very much in advance of the actual outbreak of rainfall activity over the station in association with a WD. Around the time of onset of rainfall activity at the station, these positive moisture anomalies come down to the lower troposphere. It is also observed that just prior to the onset of a WD over the..

2 illus, 8 ref

022996   Routray A;Mohanty U C;Das A K;Sam N V (NO, Indian Inst of Technol, New Delhi-110 016) : Study of heavy rainfall event over West Coast of India using analysis nudging in MM5 during ARMEX-I. Mausam 2005, 56(1), 107-120.

An attempt is made to numerically simulate one heavy rainfall event observed during 7-9 August 2002 along the west coast of India using mesoscale modeling system(MM5). The prime objective of the study is to investigate the impact of analysis nudging using conventional and non-conventional observations at high-resolution in the mesoscale model. Two numerical experiments are carried out with MM5 having a double nested domain viz. 60 km (coarse) and 20 km (inner) to study this heavy rainfall event. The first experiment, namely the control simulation (CNTL), global analyses is used as initial and boundary conditions. It is noticed that the model is not able to comprehensively capture the prominent features associated with organized convective processes. A second experiment, called the nudging simulation (NUDG), is carried out where the model initial and boundary conditions are improved after the insertion of observational data. Thereafter, 12 hrs analysis nudging is also applied to further improve the initial condition, before the model is allowed for free integration. Results indicate that the simulations are improved when four dimensional data assimilation using analysis nudging is performed.

7 illus, 2 tables, 12 ref

022995   Reddy K G;Bharathi G;Sree Ram P;Subrahmanyam M V;Krishna K M (Dep of Meteorology & Oceanography, Andhra Univ, Visakhapatnam-530 003) : The variation of surface heat fluxes during Arabian sea monsoon experiment. Mausam 2005, 56(1), 257-62.

Direct measurement of radiative fluxes on board ORV Sagar Kanya were made during Arabian Sea Monsoon Experiment (ARMEX) phases I & II for a total of 120 days. The variation of surface heat fluxes has been studied in this article. Negative values of net heat flux are predominant during the active phase of monsoon. The incoming short wave radiation is minimum on 3 August 2002 and on 8 June 2003 in association with heavy rainfall. The SST is 2°C higher during (WPE) (ARMEX-H 2003) than (OSTE)-ARMEX-2002. Also, the mean SST is 2.4°C higher during WPE than OSTE in June. During OSTE, SST is showing negative correlation (- 0.75) with wind speed and positive correlation (0.52 and 0.48) with latent heat and net heat fluxes respectively. Where as during WPE, the SST is having a positive correlation (0.74) with wind speed and a negative correlation with latent heat flux (- 0.42) and net heat flux (- 0.48). During WPE, advection is strong than the vertical net heat flux. The mean net heat flux is positive during March, April and May and is negative during June, July and August during the OSTE as well as WPE.

2 illus, 3 tables, 5 ref

022994   Rao P S (Earth System Sci Div Sci and Technol Dep, , Technology Bhawan, New Delhi-110 016, Email: [psrao@nic.in) : Arabian Sea monsoon experiment. Mausam 2005, 56(1), 1-6.

The Arabian Sea Monsoon Experiment (ARMEX) is one of the land-ocean-atmosphere field experiments implemented in June-July 2002 and March-June 2003 under the Indian Climate Research Programme. The broad scientific objectives of the ARMEX are (i) to study the offshore trough embedded mesoscale vortices (Arabian Sea convection) associated with intense rainfall events on the west coast of India during monsoon period, and (ii) to study the evolution, maintenance and the collapse of the Arabian Sea warm pool and onset phase of the monsoon. Conventional weather monitoring systems, weather satellite observational systems, ships, met-ocean buoys, automatic weather stations, surface layer meteorological towers and aircraft were deployed with state-of-the-art instrumentation for this experiment. This paper attempts to provide an overview of the ARMEX scientific objectives, implementation strategy, resource mobilization, infrastructure deployed, observational data collation, archival and initial analysis by the participating scientists.

3 illus, 13 ref

022993   Rao D V;Hari Prasad D (Meteorology & Oceanography Dep, Andhra Univ, Visakhapatnam-530 003, Email: dvb_rao@rediffmail.com) : Impact of special observations on the numerical simulation of a heavy rainfall event during ARMEX-Phase I. Mausam 2005, 56(1), 121-30.

The heavy rainfall event over west coast of India during 26 - 28 June 2002 (ARMEX Phase -1) is simulated using a high resolution mesoscale model-NCAR MM5. Two experiments were made with and without the inclusion of special observations of ARMEX - Phase I along with Quickscat and SSM/I surface winds. NCAR MM5, with four nested domains of 81, 27, 9 and 3 km resolutions, is integrated for 72 hr from 0000 UTC of 25 June 2002. The initial and boundary conditions are derived from NCEP analysis at 1 - degree resolution. Quantitative precipitation estimates and the wind fields from MM5 output are analysed. The model results indicate the formation of a mesoscale convective system and associated heavy rainfall on 27 and 28 June 2002. The model could predict heavy rainfall upto about 30 cm/day though some observations at isolated locations are up to 50 cm/day. Experiment with the inclusion of ARMEX observations and satellite wind data seem to improve the prediction of the location of the maxima and the movement of the rain band but with a slight decrease in the intensity of the heavy rainfall.

9 illus, 3 tables, 5 ref

022992   Rajagopal E N;Iyengar G R (Natn Cent for Medium Range Weather Forecasting, , A-50, Sector 62, Noida-201 307, Email: rajagopal@ncmrwf.gov.in) : Mesoscale forecasts with eta model over Indian region. Curr Sci 2005, 88(6), 906-12.

NCEP's mesoscale Eta model (Workstation Version 0.2) which was released in March 2000 has been installed on a SGI-Origin 200 workstation at National Centre for Medium Range Weather Forecasting (NCMREF). The analysis and forecasts of the operational global spectral model (T80L18) are used as the initial and boundary conditions for the Eta model runs. Since 1 January 2002, the Eta model is being run for 72 h daily and the model forecasts are displayed on the NCMRWF website (www.ncmrwf.gov.in). The Eta model forecasts for a few recent cases of monsoon systems are discussed in the study. In general, it is found that Eta model forecasts of the position and intensity of the weather systems are in reasonable agreement with the observations. Furthermore, it is found that the Eta model gives better orography-induced rainfall. Impact of model's horizontal resolution of the prediction of a monsoon system is also studied. Finally, the performance of the Eta model for the month of June 2002 is evaluated.

9 illus, 17 ref

022991   Prasada Rao C V K;Swain J;Hareesh Kumar P V; Nair P V;Panchalai V N;Shukla R K (NO, Naval Phys & Oceanographic Laboratory, Kochi-682 021) : Underwater acoustic propagation experiments during ARMEX. Mausam 2005, 56(1), 281-6.

Two-ship acoustic propagation experiments were conducted in deep waters of the Arabian Sea between 22-25 July and 7-8 August 2002 from onboard INS Sagardhwani and ORV Sagarkanya during ARMEX-I phase. The aim of this experiment was to understand the spatial (up to 30 km) and temporal (up to 24 hr) fluctuations of acoustic intensities within the surface duct. The acoustic transmissions were made from 15m depth at 2.4 KHz and 620 Hz frequencies from one ship and the signals were received at 15m and 40m depths on the second ship. The data were recorded for 10 min duration during each transmission and 30 sec averages were taken for computing acoustic intensities. Simultaneous oceanographic data on temperature (CTD and XBT), currents (ADCP) and waves (SBWR) were also recorded. Steady and homogeneous mixed layer depths of 50-60m offered an ideal environmental condition for surface duct propagation. The sea-state was moderate with significant wave height ranging from 1.5 to 2.3m. The surface and sub-surface currents in the upper 125m water column revealed the predominance of tides with change of current direction at 6 hr intervals. The current speeds were <126> 50 cm/s. The analysis of acoustic data highlighted the importance of temporal variations compared to spatial variations. Around 20 dB fluctuations in acoustic intensity were noticed for temporal variability where as only 7 dB fluctuation was observed for spatial variability.

8 illus, 6 ref

022990   Patil M N;Murthy B S;Sinha S (Indian Inst of Trop Meteoroloty, , Pune-411 008, Email: patil@tropmet.res.in) : Characteristics of mixed layer over Arabian Sea during summer monsoon-2002. Mausam 2005, 56(1), 243-50.

Marine Boundary Layer feature has been studied using the observations collected during Arabian Sea Monsoon Experiment (ARMEX) - 2002. Mixed layer heights were esitimated using radiosonde observations. It is observed that the boundary layer undergoes weak/small diurnal changes during monsoon conditions. The height of mixed layer varied from 200 - 1000 m depending on the synoptic weather conditions. Convective Boundary Layer is observed to grow rapidly with increase in mean mixed layer temperature.

6 illus, 3 tables, 9 ref

022989   Parcha S K;Singh B P;Singh B P (NO, Wadia Inst of Himalayan Geol, 33 Gen. Mahadeo Singh R, Dehra Dun 248 001, Email: Parchast@wihg.res.in) : Palaeoecological significance of ichnofossils from the early cambrian succession of the spiti valley, tethys Himalaya, India. Curr Sci 2005, 88(1), 158-62.

The diverse assemblage of ichnofossils recorded from the Early Cambrian succession of the Kunzum La Formation in Spiti basin ranges in age from the Chiung-chussuian stage of the Lower Cambrian to the Maochuangian stage of the Middle Cambrian. The trace fossil assemblage is dominated by Cruzinana, Skolithos and partially by the Nerites ichnofacies, showing behavioural diversity from suspension to deposit feeders. Distribution of the observed ichnofacies variation is attributed to the availability of oxygen and nutrient influx. Ichnofossil studies of this area further indicate that the benthic palaeocommunity was dominated by annelids or similar worm-like animals living predominantly within the sediments, while the trilobites were trailing on the sea floor. The inferred palaeoecological distribution of ichnofossil assemblage is based on modern analogue of ocean slope and shelf zones. The litho and ichnofacies association indicates anaerobic to dysaerobic trends of the ichnofauna from Nereites to Skolithos ichnofacies. Three distinctive lithofacies association have been recognized and the stratigraphic disposition reflects a general upward coarsening of the sediments.

3 illus, 23 ref

022988   Nath S K;Bhattacharya S N;Vyas M;Pal I; Sengupta P;Mitra S;Moranty W K;Ganguli S S (Geol and Geophysics Dep, Indian Inst of Technol, Kharagpur-721 302, Email: nath@gg.iitkgp.ernet.in) : The great Sumatra - Andaman earthquake of 26 December 2004 as perceived from the broadband seismograms of Indian Institute of Technology, Kharagpur seismological observatory. Curr Sci 2005, 88(9), 1381-3.

5 illus, 1 table, 13 ref

022987   Murugavel P;Gopalakrishnan V;Kamra A K (Indian Inst of Trop Meteorology, , Pune-411 008, Email: pmvelu@tropmet.res.in) : Airborne measurements of the size distribution of submicron aerosols over the Arabian sea during ARMEX-phase I. Mausam 2005, 56(1), 301-14.

Airborne measurements of the concentration and size distribution of submicron aerosols are made from 6 to 24 August 2002 over the Arabian-Sea during the Arabian Sea Monsoon Experiment (ARMEX). Results show that the aerosol concentrations at 0.9 km altitude are larger if the mixing layer depth is more than this height. Further, values of aerosol concentration at 5.1 - 6 kms altitude are one to three orders of magnitude higher if the air mass is being advected from the central Arabian Sea or the Arabian deserts in comparison to the values when the air mass is being advected up from the deserts of the northwest India. Aerosol size distributions at 0.9 km level are bimodal or trimodal with a maximum at 133 run in accumulation mode and the minima at 75 and 480 nm. Size distributions tend to become log-normal at 5.1 - 6 km altitudes. Results suggest that the processes of aerosol coagulation and gravitational settling mainly determine the evolution of modal nature of size distributions observed at lower altitudes over sea. Processes leading to modification of size distribution are also discussed.

12 illus, 1 table

022986   Murthy B S;Sivaramakrishnan S (NO, Indian Inst of Trop Meteorology, Pune-411 008, Email: siva@tropmet.res.in) : Surface fluxes over Goa during Indian monsoon. Mausam 2005, 56(1), 251-6.

Variation of surface sensible heat flux over the west coast in the premises of National Center for Antarctic and Ocear Research (NCAOR), Vasco-da-Gama (15° 21' N, 73° 51' E), Goa during Offshore trough (phase-I) and Warm pool campaigns (phase-II) of ARMEX is studied. Sensible heat flux as measured by sonic anemometer at 5 m above surface is -50 to 150 Wm^-2 during 13-28 July, 2002 (phase-I ) and -5 to 350 Wm^-2 during 21-24 April 2003 (phase II). Coastal atmospheric surface layer at Goa during night time is found to be near neutral (nearly zero heat flux) in April 2003 whereas stable (negative heat flux) in July 2002. All components of solar radiation measured by Eppley radiometers at 2 m above surface are used to compute net radiation which is 900 Wm^-2 at noon in April 2003. Net solar radiation is nearly equal to incoming short wave radiation during daytime as net long wave radiation (100 Wm^-2) compensates the loss due to reflection of short wave radiation (-100 Wm^-2 ) by the ground. High winds in the surface layer are observed during late night hours with calm winds around sunrise and after sunset giving rise to two minima in the diurnal curve. Influence of sea-breeze on the surface layer over land is discussed.

3 illus, 7 ref

022985   Morwal S B (NO, Indian Inst of Trop Meteorology, Pune-411 008, Email: morwal@tropmet.res.in) : Atmospheric boundary layer during ARMEX-2002 at stationary positions. Mausam 2005, 56(1), 221-32.

A study has been carried out to explore the salient features of the Atmospheric Boundary Layer (ABL) over the eastern Arabian Sea regions during the summer monsoon season of 2002. For this purpose the aerological observations and surface meteorological observations collected onboard ORV Sagar Kanya during the Phase-I of 2 ARMEX-2002 for the two stationary positions (30 June-10 July and 22 July - 5 August 2002) have been considered Utilizing these observations the vertical structure of the Atmospheric Boundary Layer and the temporal variation of different surface parameters has been investigated. The results showed prominent diurnal variation in different surface rological parameters. The study also revealed that there is no influence of the offshore trough on the vertical structure of the Atmospheric Boundary Layer. The ABL showed multilayered structure with shallow sub cloud layer deep cloud layer, weak stable layer and the ABL extending up to higher levels in the presence of the cyclonic circulation(2-4 August 2002). Whereas the ABL is associated with deep sub cloud layer, shallow cloud layer, strong stable layer (inversion layer) and shallow ABL depth under the influence of weak offshore trough observed along thewest coast of India.

7 illus, 2 tables, 23 ref

022984   Mohanty U c;Sam N V;Das S;Basu S (Cent for Atmospheric Sci, Indian Inst of Technol, Delhi, New Delhi, Email: mohanty@cas.iitd.ernet.in) : A study on the convective structure of the atmosphere over the West Coast of India during ARMEX-I. Mausam 2005, 56(1), 49-58.

Onset of south west monsoon (SWM) over Kerala is associated with intense convection followed by heavy rainfall over the west-coast of India. The intense rainfall events are usually associated with meso-scale convective systems embedded in large scale synoptic system over the Arabian Sea. Such deep and intense cumulus convection can have an important effect on the dynamics and energetics of large-scale atmospheric systems, because of the large magnitudes of the energy transformations associated with changes of phase of water in precipitating cumulus clouds as well as the strong updrafts and downdrafts in the troposphere. The prime objective of this study is to understand the convective structure (active/suppressed) of the atmosphere over the west-coast of India during ARMEX-I (Arabian Sea Monsoon Experiment). This study uses an approach to obtain the average structure of a cloud cluster and its interaction with the environment that enables in distinguishing the variation of kinematic and convective parameters from suppressed to convectively active process. Upper air observations obtained from four coastal land stations viz., Bombay, Goa, Mangalore and Trivandrum, alongwith that obtained over ORV Sagar Kanya are used to calculate both the convective and the kinematic parameters at the centre of the polygon formed by these observation locations. Time averaged circulation kinematic parameters and vertical velocity during active and suppressed convective phases off the west coast of India were discussed. The apparent heating and the apparent moisture sink are also estimated through residuals of the thermodynamic equations during intense and weak phases of SWM.

6 illus, 18 ref

022983   Mitra S;Wassmann R;Vlek P L G (Global Environment Res, The Energy and Resources Inst, Darbari Seth Block, Email: Sudip@teri.res.in) : An appraisal of global wetland area and its organic carbon stock. Curr Sci 2005, 88(1), 25-35.

Present discussion on density distribution of soil organic C in global wetlands could well be instrumental in formulating efficient strategies related to carbon sequestration and reduction of GHG emissions in wetland ecosystems. Effective assessment of wetlands will only take place when the available information becomes accessible and usable for all stakeholders.

4 illus, 3 tables, 66 ref

022982   Manglik A (NO, Natn Geophys Res Inst, Uppal Road, Hyderabad-500 007, Email: ajay@ngri.res.in) : Variation inblithospheric structure in the vicinity of Palghat Cauvery shear zone, southern Indian shield: inference from magnetotelluric data. Curr Sci 2005, 88(3), 497-501.

Published magnetotelluric apparent resistivity data indicate a heterogeneous nature of the lithosphere in the vicinity of the Palghat-Cauvery Shear Zone (PSCZ). Data from two locations, one in the vicinity of PCSZ and the other further south near Palani, are inverted to decipher this contrast. Results reveal the presence of a highly resistive crust underlain by a thick conducting layer and a relatively uniform average sub-crustal structure near Palani that seems to extend up to PCSZ. The sub-crustal structure in the vicinity of PCSZ in highly heterogeneous at a depth greater than 60 km and possibly represents the presence of a dipping fault at this depth. The sub-crustal structure north of PCSZ is drastically different and has high conductivity. A qualitative analysis of TE and TM mode data along Kolattur-Palani profile indicates that the conducting lithosphere laterally extends up to 60 km north of PCSZ and correlates well with the Bouguer gravity high anomaly which was earlier explained in terms of mid-crustal high-density body.

6 illus, 12 ref

022981   Mallikharjuna Rao J;Rao G V S;Widdowson M; Kelley S P (NO, Natn Geophys Res Inst, Hyderabad-500 007) : Evolution of proterozoic mafic dyke swarms of the Bundelkhand granite massif, central India. Curr Sci 2005, 88(3), 502-6.

The early proterozoic Bundelkhand Granite Massif of Central India is extensively intruded by NW-SE and NE-SW trending mafic and ultramafic dykes. These dykes are mostly dolerites with subordinate pyroxenite or lamproites, and geochemical signatures are different for the NW-SE and NE-SW trending dyke suites. ⁴⁰Ar/³⁹Ar age determinations of the dolerite dykes suggest two phases of dyke activity at ca. 2150 Ma and 2000 Ma and supported by palaeomagnetic results in this region. Apart from other magmatic emplacements, there are younger deformational events recorded by minerals (1800 Ma event recorded by some mafic regions of dykes and 6792-750 Ma given by plagioclase feldspars) subsequent to their magmatic emplacements. The dolerites are typically tholeiites and quartz normative types, while the ultramafics are komatiite or basaltic komatiite in composition and show an olivinenormative character. Most of the tholeiites display incompatible elements pattern indicative of an enriched mantle source, while those of the ultramafics indicate a depleted source.

1 illus, 1 table, 25 ref

022980   Madan O P;Mohanty U C;Iyenger G;Shivhare R P; Rao A P;Sam N V;Bhatla R (Cent for Atmospheric Sci, Indian Inst of Technol, New Delhi-110 016) : Off shore trough and very heavy rainfall events along the West Coast of India during ARMEX-2002. Mausam 2005, 56(1), 37-48.

Arabian Sea Monsoon Experiment (ARMEX) 2O02 was carried out from mid June to mid August to study the presence of off-shore trough (OST) and embedded vortices. Four cases of heavy rainfall along the west coast (rainfall exceeding 12 cm in 24 hour) of India were recorded on 14-16 June, 20-22 June, 26-28 June and 7-10 August 2002. The heavy rainfall event of 26-28 June was due to a low pressure system that moved from Bay of Bengal across Madhya Pradesh to Gujarat and adjoining Rajasthan. The other three heavy rainfall events were associated with the off shore trough and or off shore vortices. Of the various sea buoys deployed in the Arabian Sea, only one buoy located off Goa, did give hint of an OST both in strong and weak wind conditions. However, surface wind data from other buoys and QSCAT surface wind did not always support the presence of OST. The indications were very subtle and it was found difficult to observe them on the NCMRWF (National Centre for Medium Range Weather Forecasting) analysis or forecast charts. In the present study it has been observed that off shore trough may be observed in weak as well as strong monsoon conditions. However, heavy rainfall events were noticed only when the monsoon current is strong both in the Arabian Sea as well as Bay of Bengal in association with some synoptic systems. In addition, an east-west shear line in wind flow pattern extending from lower to middle or upper tropospheric levels and joining the circulation features in the Arabian Sea and Bay of Bengal has been noticed in all cases of heavy rainfall events. Meso-scale vortices/organized convection systems were also identified during heavy rainfall events on the basis of cloud features noticed in the satellite pictures and TRMM rain rate patterns.

13 illus, 4 ref

022979   Londhe A L;Padma kumari B;Kulkarni J R;Jadhav D B (NO, Indian Inst of Trop Meteorology, Pune-411 008, Email: londhe@tropmet.res.in) : Monsoon circulation induced variability in total column ozone over India. Curr Sci 2005, 89(1), 164-7.

Intra-seasonal variability of daily total column ozone (TCO) over 12 Indian stations has been studied. Total Ozone Mapping Spectrometer daily data from May to September for five year (1998-2002) have been utilized in the study. The power spectrum analysis of daily TCO data showed three dominant modes of period 3-8 days (synoptic), 10-20 days (quasi biweekly, qbw) and 30-60 days (Madden Julian Oscilltion, MJO), similar to that found to the Indian Summer Monsson Rainfall. Mean spatial distribution of the activities of these intra-seasonal modes in TCO variability over the Indian region has been studied. The spatial distribution of the synoptic mode shows the strongest activity over central India. The qbw mode shows strongest activity over northwest India. The MJO mode shows strongest activity over northern most and southern most parts of India.

3 illus, 1 table, 22 ref

022978   Krishna Kumar G V;Swain J (Naval Phys and Oceanographic Laboratory, , Kochi-682 021) : Simulation of internal waves using GM model and comparison against measurements during ARMEX-I. Mausam 2005, 56(1), 269-74.

A linear internal wave model based on the Garrett-Munk modal spectrum has been developed. The model simulates sound speed structure due to internal waves in the ocean CTD yoyo (go up and down continuously) data collected during the ARMEX-I experiment has been utilized to validate the model. Internal waves amplitudes at the experimental site are found to be <62>lm. EOF and modal decomposition analyses reveal that the modal bandwidth parameter Jx = 3 and modal energy damping parameter P = 1 or 2 and follows the GM suggested values. Comparison of the measured sound speed profiles against the simulated reveals that the GM model is capable of reproducing most of the variability due to IW in the deep-waters. The agreement between the observed and simulated perturbations is quite good.

5 illus, 10 ref

022977   Joseph K J;Harikrishnan M;Rajesh G;Premkumar K (NO, Natn Inst of Oceam Technol, chennai-601 302, Email: jossiaj@niot.res.in) : Moored buoy observations in Arabian sea warm pool. Mausam 2005, 56(1), 161-8.

Time series observations from four moored data buoys, in the south eastern Arabian Sea for a period of four months (March-June 2003) are utilized to study the characteristics of warm pool. The moored buoy observations show fair weather conditions in the pre-monsoon period with weak variable winds and calm sea conditions. High SST has been observed during the pre-monsoon warming phase. Surface met observation shows comparatively low-pressure in the region for a period of two weeks starting from the last week of April 2003. Increased wind speed and wave height with a clockwise rotation in wind direction and occasional rains are reported during that period. An interesting observation is the cooling of SST in response to the May 2003 cyclone in Bay of Bengal. Another feature during the warming phase is an oscillation of the order of 14 days observed in SST. Time series observations of salinity in the month of March show the presence of low saline water in the warm pool. A sudden drop of 0.4 psu in surface salinity was observed on 2nd April, which may be due to the advection of low saline plumes in the warm pool region and/or the local pre-monsoon showers. The onset of southwest monsoon and the associated monsoon currents dissipated the warm pool and thereafter the monsoon conditions with high winds, rough sea and requent rains prevailed in the region.

7 illus, 1 table, 11 ref

022976   Jayanthi N;Mazumdar A B;Sunitha Devi S (Meteorological Office, , Pune-411 005) : Weather in India winter season (January-February 2004). Mausam 2005, 56(1), 327-36.

1 illus, 4 tables

022975   Jat M L;Acharya M S;Jaspal Singh;Gupta A (NO, Dryland Fmg Res Stn, Arjia, Bhilwara) : Estimation of Aquifer parameters in fractured rocks under linear (non-radial) flow conditions. J appl Hydrol 2004, 17(1), 24-31.

A straight-line method has been developed for estimating aquifer parameters in fractured rocks under linear flow conditions. Constant discharge pumping test data in phyllite formation were analysed by this technique for estimation of transmissivity and storage coefficient. For estimation of these parameters straight lines were fitted to arithmetic plots of drawdowns versus square root of time since pumping started (_Ot). The results obtained were compared with values obtained by Sen (1986) method. The straight-line method yielded the least root mean square error.

4 illus, 2 tables, 10 ref

022974   Hatwar H R;Yadav B P;Rama Rao Y V (India Meteorological Dep, , Lodi Road, New Delhi-110 003, Email: hrhatwar@yahoo.com) : Prediction of western disturbances and associated weather over western Himalayas. Curr Sci 2005, 88(6), 913-20.

Two cases of intense western disturbances which affected the northwest India have been investigated using the India Meteorological Department's operational limited area analysis and forecast system. The model results are compared with the synoptic observations, which have been enriched by additional stations installed under the national propject `Parwat'. The analysis shows that the 24-hour model forecasts are in good agreement with the observations both in respect of western disturbance's movement and intensification. Even the numerical model could predict the spatial distribution of precipitation with a high success rate and was found to be very useful in providing numerical guidance in day-to-day operational short range forecasts.

9 illus, 1 table, 4 ref