On the measurement of the surface energy budget over a land surface during the summer monsoon

The measurement of surface energy balance over a land surface in an open area in Bangalore is reported. Measurements of all variables needed to calculate the surface energy balance on time scales longer than a week are made. Components of radiative fluxes are measured while sensible and latent heat fluxes are based on the bulk method using measurements made at two levels on a micrometeorological tower of 10m height. The bulk flux formulation is verified by comparing its fluxes with direct fluxes using sonic anemometer data sampled at 10Hz. Soil temperature is measured at 4 depths. Data have been continuously collected for over 6 months covering pre-monsoon and monsoon periods during the year 2006. The study first addresses the issue of getting the fluxes accurately. It is shown that water vapour measurements are the most crucial. A bias of 0.25% in relative humidity, which is well above the normal accuracy assumed by the manufacturers but achievable in the field using a combination of laboratory calibration and field intercomparisons, results in about 20W m⁻² change in the latent heat flux on the seasonal time scale. When seen on the seasonal time scale, the net longwave radiation is the largest energy loss term at the experimental site. The seasonal variation in the energy sink term is small compared to that in the energy source term.     

Rhenium (Re)–Osmium (Os) geochronology of the Proterozoic Sirban Limestone Formation,NW Himalaya

The Proterozoic Sirban Limestone Formation (SLFm) exposed in a number of inliers in Jammu (India), NW Himalaya is a potential target for hydrocarbon and ore mineral exploration. The structural complexity not only makes correlation of the SLFm with coeval hydrocarbon producing Proterozoic formations in the neighbouring Salt Range in Pakistan and elsewhere in the world extremely difficult, but also limits the understanding of the genesis of sedimentary hosted mineral deposits. The base of the SLFm inliers is not exposed anywhere in the region and the age of this sequence has been suggested to range from Palaeoproterozoic to Neoproterozoic.     

Remote Sensing and GIS based groundwater potential mapping for sustainable water resource management of Lidder catchment in Kashmir Valley,India

The valley of Kashmir is blessed with abundant water resources. However, high population growth and concentration of population at favorable locations have resulted in increased demand for water. The problem is further aggravated in Lidder catchment where unplanned tourism development has resulted in deterioration of water quality. Multi-Criteria Evaluation (MCE) approach is adopted using IRS P6 LISS III satellite data 2010, geological map published by Geological Survey of India, toposheets prepared by Survey of India, 1961 and field observation. Seven thematic layers (slope, lineament density, drainage density, soil, geology, geomorphology and land use land cover) are generated in GIS environment and weighted according to their relative relevance to groundwater occurrence. Knowledge-based weights and ranks are normalized, and a weighted linear combination technique is adopted to determine the groundwater potential (GWP). The catchment is divided into five zones of very high, high, medium, low and very low GWP. The results show that 50.22% of the total catchment area, which is uninhabited, has very low GWP. However, the densely populated southern part of the catchment has moderate to very high GWP. The study demonstrates that MCE using remote sensing and GIS technology could be efficiently employed as a very useful tool for the assessment and management of groundwater resources especially in regions where data is poor.     

Spatiotemporal trends of temperature extremes in Bangladesh under changing climate using multi-statistical techniques

Theoretical and Applied Climatology - The rise in the frequency and magnitude of extreme temperature phenomena across the globe has led to the recurrent incidence of global climate hazards, which...     

Paleoseismological investigations along Joggers Park Fault,Port Blair,South Andaman: Implications towards delineation of blind thrusting and related crustal deformation through ground penetrating radar (GPR) and electrical resistivity techniques (ERT and VES)

A comprehensive paleoseismological investigations was carried out along Joggers Park Fault (striking NW-SE) reveals pervasive traces of active compressional tectonics (blind thrusting) and shallow-surface recent tectonic signatures along the fault. The geometry and trends in the tectonic deformation of the blind zone (shallow-subsurface stratigraphy) were examined with GPR and electrical resistivity tomography (ERT) and vertical electrical sounding (VES), strongly demonstrates severe tectonic deformation (persistent tectonic style) from Quaternary to Holocene times in a compressive stress regime. The surface manifestation of deformation (topographic expression) along the fault can be marked as hanging wall uplift and can be visually observed in the exposed sections at nearly half kilometer distance from the table land of Joggers Park in the form of a well-defined disconnected high angle thrust fault scarp (reverse fault). The reverse fault kinematically and intimately linked with underlying fault geometry provides adduced evidence to evaluate strike displacement profiles (displacement length relationship) along the fault. In addition, deformed stacked colluvial wedge below the scarp represents a powerful basis to calibrate recent and long term slip rates of the underlying fault.     

Ground-based calibration and characterization of the Fermi gamma-ray burst monitor detectors

One of the scientific objectives of NASA’s Fermi Gamma-ray Space Telescope is the study of Gamma-Ray Bursts (GRBs). The Fermi Gamma-Ray Burst Monitor (GBM) was designed to detect and localize bursts for the Fermi mission. By means of an array of 12 NaI(Tl) (8 keV to 1 MeV) and two BGO (0.2 to 40 MeV) scintillation detectors, GBM extends the energy range (20 MeV to > 300 GeV) of Fermi’s main instrument, the Large Area Telescope, into the traditional range of current GRB databases. The physical detector response of the GBM instrument to GRBs is determined with the help of Monte Carlo simulations, which are supported and verified by on-ground individual detector calibration measurements. We present the principal instrument properties, which have been determined as a function of energy and angle, including the channel-energy relation, the energy resolution, the effective area and the spatial homogeneity.     

Drive-Control System for the TACTIC Gamma-Ray Telescope

A PC-based drive-control system has been developed for the altitude-azimuth mounted TACTIC -ray telescope to control the speed and direction of motion of its 2-axes. Details of various hardware components chosen for the telescope, including hybrid-stepper motor, 16-bit absolute encoder and CAMAC-based programmable stepper motor controller, are discussed in this paper. The telescope-control strategy, based on the position-loop with a proportional type control for the source-seek mode and the on/off type control for the tracking mode, is explained in detail. Some important performance features of the telescope, including its blind-spot size, drive-system backlash and encoder-error compensation, are also presented. The drive system has been extensively field-tested and has been operating satisfactorily during observation campaigns carried out since March 1997 with the TACTIC Imaging Element. A tracking accuracy of ±3 arc-minutes has been achieved. A test report of its performance, with regard to its tracking accuracy on the basis of successful detection of TeV -rays from the active galaxy Markarian 501 in April–May 1997, is also presented.     

Long-term shoreline changes of Mulki-Pavanje and Nethravathi-Gurupur estuaries,Karnataka

Significant morphological changes are noticed in the Nethravathi-Gurupur and Mulki-Pavanje estuaries. Satellite images of IRS-1A and 1B on multispectral bands and multidates (1988–1993) were made use of in addition to aerial photographs (photographed in 1979) and Survey of India Topographical maps (surveyed during 1910 and 1967). The Nethravathi-Gurupur estuary has slightly shifted northward whereas the Mulki-Pavanje estuary has shifted northward considerably. The multidated data product study reveals advancement of land.     

Inertial-Dissipation flux measurements over south Bay of Bengal during BOBMEX-Pilot experiment

This paper describes measurement of air-sea parameters and estimation of sensible and latent heat fluxes by the “Inertial-Dissipation” technique over south Bay of Bengal. The data were collected on ORV Sagar Kanya during BOBMEX-Pilot cruise during the period 23rd October 1998 to 12th November 1998 over south Bay of Bengal. The fluxes are estimated using the data collected through fast response sensors namely Gill anemometer, Sonic anemometer and IR Hygrometer. In this paper the analyses carried out for two days, one relatively cloud free day on November 3rd and the other cloudy with rain on November 1st, are presented. Sea surface and air temperatures are higher on November 3rd than on November 1st. Sensible heat flux for both the days does not show any significant variation over the period of estimation, whereas latent heat flux is more for November 3rd than November 1st. An attempt is made to explain the variation of latent heat flux with a parameter called thermal stability on the vapor transfer from the water surface, which depends on wind speed and air to sea surface temperature difference.     

Examining the feasibility of air shower core-location from polarization properties of associated Cherenkov light

Based on this exploratory investigation involving CORSIKA simulation code generated Cherenkov photons and a linearly polarized, hypothetical photon beam, we make a case here for exploiting polarization properties of atmospheric Cherenkov events for providing an independent method for locating air-shower cores by a TACTIC-like array of atmospheric Cherenkov telescopes. Preliminary results based on simulations indicate that for a 3 TeV γ-ray having ∼30% degree of polarization for its associated Cherenkov light at a core distance of ∼100 m, core location can be found with an error of ∼27 m. Deceased This revised version was published online in July 2006 with corrections to the Cover Date.