Characterization of Black Carbon in the Ambient Air of Agra,India:Seasonal Variation and Meteorological Influence

This study characterizes the black carbon in Agra, India home to the Taj Mahal—and situated in the Indo-Gangetic basin.The mean black carbon concentration is 9.5 μg m~(-3)and, owing to excessive biomass/fossil fuel combustion and automobile emissions, the concentration varies considerably. Seasonally, the black carbon mass concentration is highest in winter, probably due to the increased fossil fuel consumption for heating and cooking, apart from a low boundary layer. The nocturnal peak rises prominently in winter, when the use of domestic heating is excessive. Meanwhile, the concentration is lowest during the monsoon season because of the turbulent atmospheric conditions and the process of washout by precipitation. The ratio of black carbon to brown carbon is less than unity during the entire study period, except in winter(December). This may be because that biomass combustion and diesel exhaust are major black carbon contributors in this region, while a higher ratio in winter may be due to the increased consumption of fossil fuel and wood for heating purposes. ANOVA reveals significant monthly variation in the concentration of black carbon; plus, it is negatively correlated with wind speed and temperature. A high black carbon mass concentration is observed at moderate(1–2 m s~(-1)) wind speed, as compared to calm or turbulent atmospheric conditions.     

A high speed near infrared photometer for lunar occultation studies

A recently developed near infrared high speed photometer intended for lunar oc-cultation studies is described. The primary scientific objective is to reach milli arc second levels of angular resolution so that circumstellar structure of the occulted sources can be resolved. Near infrared sky brightness close to the lunar limb is also studied. Angular diameter derived from the observed occultation of IRC +20169 is presented and system performance discussed.     

Infrared Observations of Comet Hale–Bopp (C/1995 O1) from Gurushikhar Observatory

During the recent apparition of comet Hale—Bopp (1995 O1) near infrared photometric observations were carried out in the J, H, K filter bands and also in the 3.0—3.4 μm region at the 1.2 m telescope at Gurushikkar, India. The effective temperature of the comet was substantially higher than the equilibrium blackbody temperature. A mean superheat value of 1.83 was derived in the post-perihelion phase which implies that a large fraction of the grain population are made up of small and hot grains with radii <0.5 μm. High albedo values of ∼0.4 were also derived in the scattering angle range 135° to 160° which could explain the unusual brightness of comet Hale—Bopp. This revised version was published online in July 2006 with corrections to the Cover Date.     

Decadal changes in the relationship between the Indian and Australian summer monsoons

In this study, we investigate a long-term modulation in the relationship between Indian summer monsoon rainfall with the subsequent Australian summer monsoon rainfall. The two monsoon rainfall time series are significantly correlated at 0.3 at the 99 % confidence level. However, the relationship weakens during the 1932–1966 period, with the inter-monsoon correlation for the period falling below statistical significance. We find that this modulation is consistent with a breakdown of the typical El Niño-Southern Oscillation (ENSO) influence on sea surface temperature in the northern region of Australia, during this period. In addition, a change in the relative influences of ENSO and Indian Ocean Basin-wide Warming sea surface temperature anomalies on the Australian summer monsoon rainfall is also apparent across different time periods.     

Optical interferometric observations of a transient event of 1986 March 13 in the coma of Comet Halley

During the recent apparition of Comet Halley in 1985-86 a transient ionic event in the form of a blob of H₂ O⁺ emission was recorded in thecoma at ～ 0^h UT on 1986 March 13. Observations were carried out using a special IHW filter for H₂ O⁺ emission at 7000 å/175 å, a 35 cm telescope, a Fabry-Perot interferometer and an image intensifier camera from Gurushikhar, Mt Abu. (24?39’N,72? 47’E). A Fabry-Perot inter-ferogram in Ha taken a few minutes later at the same location reveals strong hydrogen emission (Hα) associated with the blob. The velocity field in the blob is structured with relative velocities upto ～ 35km s^?1. The event is interpreted as arising due to the sector boundary crossing of the interplanetary magnetic field by the comet     

Adsorption of Chromium(III), Nickel(II), and Copper(II) from Aqueous Solution by Activated Alumina

The possible use of activated alumina powder (AAP) as adsorbent for Cr(III), Ni(II), and Cu(II) from synthetic solutions was investigated. The effect of various parameters on batch adsorption process such as pH, contact time, adsorbent dosage, particle size, temperature, and initial metal ions concentration were studied to optimize the conditions for maximum metal ion removal. Both higher (molar) and lower (ppm) initial metal ion concentration sets were subjected to adsorption on AAP. Adsorption process revealed that equilibrium was established in 50 min for Cr(III) at pH 4.70, 80 min for Ni(II) at pH 7.00, and 40 min for Cu(II) at pH 3.02. Percentage removal was found to be highest at 55°C for Cr(III) and Ni(II) with 420 µm and 45°C for Cu(II) with 250‐µm particle size AAP. A dosage of 2 g for Cr(III), 8 g for Ni(II), and 10 g Cu(II) gave promising data in the metal ion removal. The adsorption process followed Langmuir as well as Freundlich models. The thermodynamics of adsorption of these metal ions on activated aluminum indicated that the adsorption was spontaneous and endothermic in nature. Present study indicates that AAP can act as a promising adsorbent for industrial wastewater treatment.     

Environmental impact on groundwater of Maheshwaram Watershed,Ranga Reddy district,Andhra Pradesh

Maheshwaram watershed is situated in Ranga Reddy district of at a distance of about 30 km south of Hyderabad. The watershed has an area of 53 km² and has hard rock aquifers with semi-arid climate. The study area has been expanding at a fast pace and now has the distinction of being one of the fastest growing urban centers, facing the problem of groundwater depletion and quality deterioration due to the absence of perennial source of surface water and also due to over exploitation. Human activities involving industrial and agricultural development and the inadequate management of land and water resources have, directly or indirectly resulted in the degradation of environment viz. water and soil.     

Repercussions of solar high energy protons on ozone layer during super storms

We are very aware of the importance of the ozone layer, without which life on the Earth would not have evolved in the way it has. Solar storms carry energetic protons into the Earth's upper atmosphere,where they boost production of nitrogen oxides which are known as ozone killers and which ultimately increase ultraviolet(UV) radiations. In the present study, we estimate the effects of solar energetic protons during super storms(Dst index -300 nT) over the total ozone column for the last 32 yr. We select a total of seven super storm events that occurred during solar cycles 22–24(for the last 32 yr) having Dst index -300 nT. To that end, we apply superposed epoch analysis(SEA) to verify the impact of storm events on the quantitative variation of total ozone column and on UV radiations during super storm events.After completing the empirical analysis, we conclude that the ozone column gets depleted significantly(22±6.8%) as proton density increases during super storm events and this decrement in the ozone level is further responsible for a substantial increase(26±11.2%) in peak UV radiation intensities.     

Solar Activity,Lightning and Climate

The physics of solar forcing of the climate and long term climate change is summarized, and the role of energetic charged particles (including cosmic rays) on cloud formation and their effect on climate is examined. It is considered that the cosmic ray-cloud cover hypothesis is not supported by presently available data and further investigations (during Forbush decreases and at other times) should be analyzed to further examine the hypothesis. Another player in climate is lightning through the production of NO_x; this greenhouse gas, water vapour in the troposphere (and stratosphere) and carbon dioxide influence the global temperature through different processes. The enhancement of aerosol concentrations and their distribution in the troposphere also affect the climate and may result in enhanced lightning activity. Finally, the roles of atmospheric conductivity on the electrical activity of thunderstorms and lightning discharges in relation to climate are discussed.     

Cretaceous Environments of Afghanistan:A Synthesis Based on Selected Sections

1IntroductionThe Late Mesozoic sequences of Afghanistan are important in understanding the geodynamic evolu-tion of the northwestern part of South Asia, in par-ticular the transgressive and regressive history of the northwestern part of the Tethys connecting Iran to the west and the northern Indian Subcontinent to the east. Jurassic to Upper Cretaceous sedimentary seque-nces were initially studied by Griesbach (1885 ~1887) and Hayden (1880~1901) through several traverses in northern an…