An Overview of the Land Surface Processes Experiment (Laspex) over a Semi-Arid Region of India

To understand and quantify the land-surface-vegetation interactionwith the atmospheric boundary layer, and validate or improve upon the existing surfaceflux parameterization schemes in various weather forecast models, a LAnd SurfaceProcesses EXperiment (LASPEX), was designed and executed in the semi-arid regionof Gujarat, India during January 1997–December 1998. Micrometeorological tower observations,soil and vegetation parameters, radiation, turbulence and upper airobservations were taken continuously for two years at five sites, separated by about60–100 km from each other. Towers of 9 m height with instruments at four levels wereinstalled at sites that are agricultural fields and characterized with a variety of soilproperties, vegetation and diverse crops. An overview of the experiment is presented.Some results, such as the seasonal variation of surface energy balance and turbulence statistics,are discussed.     

Temperature stratification of the atmospheric boundary layer over the Deccan Plateau,India, during the summer monsoon

The vertical and horizontal temperature structure of the atmospheric boundary layer (ABL) were studied using aircraft observations made in the lowest 2.4 km above ground level during the summer monsoon.The vertical temperature structure of the ABL in the region may be classified into the following four categories.Category The ABL consisted of two layers of thickness 700–900 m separated by a thin transition layer. The lapse rates in the former two layers were dry adiabatic.Category The lowest layer of the ABL of thickness 400–600 m was adiabatically stratified and the overlying layer was stable with gradients of potential temperature 4–5°C km^–1. The stable layer contained a thin adiabatic stratified layer of 200–300 m thickness at a height of 1.5 km.Category The lowest 200–400 m layer of the ABL was adiabatically stratified and the overlying layer was stable with potential temperature gradients of 5–6 °C km¹.Category The ABL was mainly stable with potential temperature gradients of 6 °C km^–1 or greater. Occasionally thin layers with adiabatic stratification were found embedded in the ABL.The temperature distribution of the horizontal temperature at 900 m was mainly normal. The high-frequency portion of the spectra lying between 0.05 and 0.16 Hz (corresponding to wave length 1 km to 300 m) oscillated around the –\2/3 power law line. The spectral curve showed a significant peak at 0.011 Hz having a wave-length of 5 km.Department of Geoscience, North Carolina State University, Raleigh, NC, 27650, U.S.A.     

Health impacts of coal and coal use: possible solutions

Coal will be a dominant energy source in both developed and developing countries for at least the first half of the 21st century. Environmental problems associated with coal, before mining, during mining, in storage, during combustion, and postcombustion waste products are well known and are being addressed by ongoing research. The connection between potential environmental problems with human health is a fairly new field and requires the cooperation of both the geoscience and medical disciplines. Three research programs that illustrate this collaboration are described and used to present a range of human health problems that are potentially caused by coal. Domestic combustion of coal in China has, in some cases, severely affected human health. Both on a local and regional scale, human health has been adversely affected by coals containing arsenic, fluorine, selenium, and possibly, mercury. Balkan endemic nephropathy (BEN), an irreversible kidney disease of unknown origin, has been related to the proximity of Pliocene lignite deposits. The working hypothesis is that groundwater is leaching toxic organic compounds as it passes through the lignites and that these organics are then ingested by the local population contributing to this health problem. Human disease associated with coal mining mainly results from inhalation of particulate matter during the mining process. The disease is Coal Worker's Pneumoconiosis characterized by coal dust-induced lesions in the gas exchange regions of the lung; the coal worker's “black lung disease”.     

Gamma/hadron segregation for a ground based imaging atmospheric Cherenkov telescope using machine learning methods: Random Forest leads

A detailed case study of γ-hadron segregation for a ground based atmospheric Cherenkov telescope is presented. We have evaluated and compared various supervised machine learning methods such as the Random Forest method, Artificial Neural Network, Linear Discriminant method, Naive Bayes Classifiers, Support Vector Machines as well as the conventional dynamic supercut method by simulating triggering events with the Monte Carlo method and applied the results to a Cherenkov telescope. It is demonstrated that the Random Forest method is the most sensitive machine learning method for γ-hadron segregation.     

Volume contents 57 nos. 1-4

Volume Contents

Volume contents 57 nos. 1-4     

Charged anisotropic models for quark stars

We perform a detailed physical analysis for a class of exact solutions for the Einstein–Maxwell equations. The linear equation of state consistent with quark stars has been incorporated in the model. The physical analysis of the exact solutions is performed by considering the charged anisotropic stars for the particular nonsingular exact model obtained by Maharaj, Sunzu and Ray. In performing such an analysis we regain masses obtained by previous researchers for isotropic and anisotropic matter. It is also indicated that other masses and radii may be generated which are in acceptable ranges consistent with observed values of stellar objects. A study of the mass-radius relation indicates the effect of the electromagnetic field and anisotropy on the mass of the relativistic star.     

Fish harvest tags: An alternative management approach for recreational fisheries in the US Gulf of Mexico

This paper explores the potential adaptation of harvest tags to the Gulf of Mexico recreational reef fish fishery. The discussion addresses conceptual, theoretical, and practical issues surrounding the application of harvest tags, as well as challenges and opportunities related to the design of tag programs. A review of hunting and fishing tag programs around the world and analysis of Gulf recreational fisheries suggests that tags have the potential to improve control over total catches, increase economic benefits and provide better information for fishery management. Results also provide insight into potential use of fish tags in large-scale recreational fisheries nationwide.     

Southwest Pacific subtropical mode water: A climatology

The large-scale distribution and changes in Southwest Pacific subtropical mode water (STMW) are investigated and discussed. The paper presents for the first time geographic maps showing the spatial distribution of STMW thicknesses, with a vertical temperature gradient <2.0 °C/100 m occupying the 14–20 °C range below the mixed layer depth, across the entire Southwest Pacific region. STMW changes in areal thickness extent, vertical cross-sectional area along selected transects, and total volume, are examined on seasonal and interannual time scales between 1973 and 1988.We find that STMW extends across the entire width of the Tasman Sea in a very broad swath between the Tropical Convergence in the north (just to the south of New Caledonia), the southeast Australian coast in the west to as far south as 39°S (likely due to the southward extension of the EAC), and eastwards along the Southern STMW boundary in a meandering pathway that broadly follows the Tasman Front. The total STMW volume across the region (i.e., west of 180°) varies seasonally by a factor of more than three between the estimated maximum of 6.6 (±0.5) × 10¹⁴ m³ in October and minimum of 1.9 (±0.4) × 10¹⁴ m³ in May. Interannual variations O (±0.5 × 10¹⁴ m³) are also observed in the spatial extent of the thick mode water and its total volume. El Niño composite maps show an anomalous thickening of the STMW during the El Niño year with October positive thickness anomalies in excess of +20 m (total volume anomaly of +0.6 × 10¹⁴ m³) manifested throughout the subtropical gyre interior as far north as New Caledonia. Total volume anomalies tend to be positive from January of the El Niño year through to the July following (18 months). The maximum correlation coefficient r = −0.3 between 3-monthly STMW volume anomalies and the Southern Oscillation index is statistically significant at the 95% confidence level. We conclude that during the anomalous cooling of the upper Southwest Pacific Ocean in the El Niño year, winter-time convection and STMW formation is enhanced across the region resulting in an El Niño – Southern Oscillation climate signal that is identifiable below the mixed layer by the increased STMW volume which persists through to the following winter. Finally, some evidence for the possible decadal modulation of the STMW variability is also discussed.     

Characterization of Organic Acids in Dew Collected on Surrogate Surfaces

Levels of formate and acetate in dew were measured at Dayalbagh, India, usingsurrogate surfaces. The dew formed per night ranged between 0.06 lm^–2 and 1.38 l m^–2, with an average of 0.59l m^–2. pH ranged between 6.7 and 7.4. Mean concentrations offormate and acetate in dew were 10.2 ± 10.2 eql^–1 and 7.5 ± 4.5 eq l^–1,respectively. The correlation coefficient between the two ions was 0.80 (p =0.001), which suggested that concentrations of these species in dew are linkedtogether. They have either common or different sources with fairly constantstrengths or products of same reaction. Good correlation of formate andacetate with Ca (r = 0.82 and r = 0.70, respectively) and Mg (r = 0.74 and r= 0.71, respectively) suggested that these ions may be associated with Ca andMg after the neutralization process. Deposition rates for formate and acetatein dew per night were 10.2 ± 7.22 mol m^–2 pernight and 4.6 ± 2.2 mol m^–2 per night,respectively. The theoretical Henry's law constant (K^* _H)and the field-observed Henry's law coefficient (K^* _H) ascalculated from concurrent measurements of gas phase and dew for both acidsshowed large discrepancies of three orders of magnitude.