भारत का उज्वल अतीत और अगले सहस्राब्दी की चुनौत्तियां

भारत का उज्वल अतीत और अगले सहस्राब्दी की चुनौत्तिया

The dependence of deep cloud mass flux and area cover on convective and large-scale processes

A framework has been developed that brings together the important physical parameters and processes governing the vertical mass flux in deep convective clouds and their area cover. The main result is a simple relation for the cloud mass flux and area fraction in terms of the large-scale radiative cooling, environmental stratification, and the extent of lateral entrainment of the ambient air by the convective systems. It is shown that the contribution of the moist processes to the total vertical mass flux in deep clouds can become comparable to that of the large-scale radiative component, and thus the neglect of these subsynoptic-scale processes can severely underestimate the convective activity. Further, it is argued that the consideration of moist processes is not merely a question of the inclusion of a correction factor in the relationship, but the uncertainty that needs to be overcome before meaningful predictions of deep cloud area cover can be achieved

The Indian drought of 2002-a sub-seasonal phenomenon?

A major drought occurred over India in the year 2002 with a seasonal rainfall deficit of 21.5%, a result of 56% below normal rainfall in the month of July. The largest anomalies occurred in the western parts of India, when an Indian monsoon field experiment was in progress there. The present study is based primarily on data collected from a research ship that was deployed 100-250 km off the west coast of India for the experiment. Surface and upper air observations made over the eastern Arabian Sea during July 2002 are presented. Sea-surface conditions were favourable for supporting deep convection over the study area. Strong atmospheric inversions around 800 hPa prevented the growth of cumulonimbus during the first half and towards the end of July. A second inversion above the melting level was also prominently present. The strength and persistence of the inversions are unusual. Back-trajectory analysis reveals a major change in the low-level circulation during July 2002 with frequent advection of dry air from over the deserts around the eastern Arabian Sea instead of marine air from across the equator

Some salient features of the atmosphere observed over the north Bay of Bengal during BOBMEX

This paper describes the near surface characteristics; vertical variations based on the observations made at 7.5° N; 89° E from ORV Sagar Kanya in the north Bay of Bengal during the Bay of Bengal Monsoon Experiment (BOBMEX) carried out in July-August 999. BOBMEX captured both the active; weak phases of convection. SST remained above the convection threshold throughout the BOBMEX. While the response of the SST to atmospheric forcing was clearly observed; the response of the atmosphere to SST changes was not clear. SST decreased during periods of large scale precipitation; increased during a weak phase of convection. It is shown that the latent heat flux at comparable wind speeds was about 5-50% lower over the Bay during BOBMEX compared to that over the Indian Ocean during other seasons; tropical west Pacific. On the other hand; the largest variations in the surface daily net heat flux are observed over the Bay during BOBMEX. SST predicted using observed surface fluxes showed that -D heat balance model works sometime but not always; horizontal advection is important. The high resolution Vaisala radiosondes launched during BOBMEX could clearly bring out the changes in the vertical structure of the atmosphere between active; weak phases of convection. Convective Available Potential Energy of the surface air decreased by - kJ kg-1 following convection; recovered in a time period of one or two days. The mid tropospheric relative humidity; water vapor content; wind direction show the major changes between the active; weak phases of convectio

Equipartition of Current in Parallel Conductors on Cooling Through the Superconducting Transition

Our experiments show that for two or more pieces of a wire, of different lengths in general, combined in parallel and connected to a dc source, the current ratio evolves towards unity as the combination is cooled to the superconducting transition temperature Tc, and remains pinned at that value below it. This re-distribution of the total current towards equipartition without external fine tuning is a surprise. It can be physically understood in terms of a mechanism that involves the flux-flow resistance associated with the transport current in a wire of type-II superconducting material. It is the fact that the flux-flow resistance increases with current that drives the current division towards equipartition.Comment: Revised version of J.Phys. Condens.Matter; vol. 18(2006) L143-L147 14 pages including 3 figures; provided an explanation in terms of the physical mechanism of flux flow induced resistance that is proportional to the impressed current. We are adding a simple, physically robust derivation of our equipartition without taking resort to the minimum dissipation principl

Guidelines issued by Karnataka Purse Seine Fishermen's Association (Mangalore Branch) to avoid conflicts among purse seine operators

Karnataka Purse seine Fishermen's Association was formed in 1973 and registered in 1979 (Reg. No. 80/79-80) at Mangalore. Its objective is to redress the grievances of the marine fishing community of the area , to provide welfare measures to the members of the association in particular and to avoid clashes and conflicts among fishermen on fishing rights and to solve the complaints and other problems peacefully by conducting meetin

Surface meteorological instrumentation for BOBMEX

Although India has a long experience in ship-borne experiments and oceanographic instrumentation, the atmospheric component has not received much attention in the past. In this paper, the basis of the atmospheric instrumentation system assembled for use on board ORV Sagar Kanya for the BOBMEXPilot experiment is described along with some representative results. Wherever possible, Woods Hole's IMET recommendations for meteorological sensors for applications in the marine environment have been followed to keep our measurements in par with international standards. The sensors were tested during the BOBMEX-Pilot experiment and all sensors worked well. Velocity, humidity and temperature data have been successfully collected using fast sensors. It is shown that the component due to the ship's pitching motion can be removed from the measured vertical velocity by making use of an accelerometer. This makes it possible to calculate the surface fluxes by direct methods

A note on the record of juveniles of Rastrelliger kanagurta (Cuvier) in the distant waters off Ratnagiri

Mackerel fishery of India is constituted mainly by Rastrelliger kanagurta. Young slages of it are reported to be caught only occasionally from the easl and west coast of our countr

A note on tbe record of juveniles of Rastrelliger kanagurta (cuvier) in the distant waters off Ratnagiri

Mackerel fishery of India is constituted mainly by RastrelJiger kanagurta. Young stages of it are reported to be caught only occasionaliy from the east and west coast of our country ,. Recently larval and post larval stages of the mackerel .have, however, been identified in the plankton 2-3. The spawning ground of the species is not yet clearly known