Impact of Ganges–Brahmaputra interannual discharge variations on Bay of Bengal salinity and temperature during 1992–1999 period

This study investigates the impact of monthly Ganges–Brahmaputra river discharge variations on Bay of Bengal salinity and temperature during the period 1992–1999. The Ganges–Brahmaputra river discharge is characterized by a well-defined seasonal cycle with strong interannual variations. The highest/lowest yearly peak discharge occurs in summer 1998/summer 1992, with 1998 value amounting to twice that of 1992. This river discharge is then used to force an ocean general circulation model. Our main result is that the impact of these rivers on the variability of Bay of Bengal sea surface salinity is strong in the northern part, with excess run-off forcing fresh anomalies, and vice versa. Most of the years, the influence of the interannual variability of river discharge on the Bay salinity does not extend south of ~10°N. This stands in contrast with the available observations and is probably linked to the relatively coarse resolution of our model. However, the extreme discharge anomaly of 1998 is exported through the southern boundary of the Bay and penetrates the south-eastern Arabian Sea a few months after the discharge peak. In response to the discharge anomalies, the model simulates significant mixed-layer temperature anomalies in the northern Bay of Bengal. This has the potential to influence the climate of the area. From our conclusions, it appears necessary to use a numerical model with higher resolution (both on the horizontal and vertical) to quantitatively investigate the upper Bay of Bengal salinity structure.     

Plant studies in Himachal Pradesh,Western Himalaya: a systematic review

Owing to a predicted rise in temperature, increase in precipitation and the escalating anthropogenic stresses, the Himalayan ecosystems are the most threatened non-polar regions of the world. In the past, there have been racing extinctions and range shifts of several life forms in this region, particularly of the plant species. Therefore, consistent qualitative and quantitative records on botanical baseline data on a regular basis are indispensable. The current communication attempts to provide a detailed account on the current state of knowledge and research gaps in floristic studies of Himachal Pradesh, Western Himalaya. Based on an extensive review of more than 140 studies in the form of scientific peer reviewed literature on floristics, medicinal and aromatic plants(MAPs), rare, endangered, threatened and endemic species and ethno-botany, it is revealed that the number of floristic studies in Himachal Pradesh have surged in the past years but studies pertaining to the lower plants remain meagre. Unfortunately, the remote valleys including micro-watersheds lying in the coldarid regions are relatively less studied in terms of available growing stock and population status of MAPs. Depleting traditional ethno-botanical knowledge has been the major concern and, many threatened MAPs need to be accessed globally following IUCN standards. Thus, documentation of the conservation status of key MAPs, setting aside conservation areas around viable populations of threatened species, developing germplasm banks of the priority MAPs and monitoring the impacts of climate change has been suggested.     

Benford’s Distribution in Extrasolar World: Do the Exoplanets Follow Benford’s Distribution?

In many real life situations, it is observed that the first digits (i.e., 1,2,…,9) of a numerical data-set, which is expressed using decimal system, do not follow a uniform distribution. In fact, the probability of occurrence of these digits decreases in an almost exponential fashion starting from 30.1 % for 1 to 4.6 % for 9. Specifically, smaller numbers are favoured by nature in accordance with a logarithmic distribution law, which is referred to as Benford’s law. The existence and applicability of this empirical law have been extensively studied by physicists, accountants, computer scientists, mathematicians, statisticians, etc., and it has been observed that a large number of data-sets related to diverse problems follow this distribution. However, except two recent works related to astronomy, applicability of Benford’s law has not been tested for extrasolar objects. Motivated by this fact, this paper investigates the existence of Benford’s distribution in the extrasolar world using Kepler data for exoplanets. The quantitative investigations have revealed the presence of Benford’s distribution in various physical properties of these exoplanets. Further, some specific comments have been made on the possible generalizations of the obtained results, its potential applications in analysing the data-set of candidate exoplanets.     

EFFECT OF VERTICAL CONTACT ON WENNER RESISTIVITY SOUNDINGS*

The allowance for the influence of a vertical contact is evaluated on Wenner resistivity sounding curves, which are graphically constructed on bilogarithmic paper over simple composite earth models consisting of a vertical contact separating two- or three layered earth on one side and a homogeneous medium on the other side. The error incurred in the graphical constructions is explored. Finally, the use of these graphically constructed sounding curves is shown in the interpretation of two Wenner field soundings measured in a complex geologic area.