Trends and Change-Point in Satellite Derived Phenology Parameters in Major Wheat Growing Regions of North India During the Last Three Decades

The virtual certainty of the anticipated climate change will continue to raise many questions about its aggregated impact of environmental changes on our regional food security in imminent future. Crop responses to these changes are certain, but its exact characteristics are hardly understood at regional scale due to complex overlapping effects of climate change and anthropogenic manipulation of agro-ecosystem. This study derived phenology of wheat in north India from satellite data and analyzed trends of phenology parameters over last three decades. The most striking change-point period in phenology trends were also derived. The phenology was derived from two sources: (1) STAR-Global vegetation Health Products-NDVI, and (2) GIMMS-NDVI. The results revealed significant earliness in start of growing season (SOS) in Punjab and Haryana while delay was found in Uttar Pradesh (UP). End of the wheat season almost always occurred early, to even those place where SOS was delayed. Length of growing season increased in most of Punjab and northern Haryana whereas its decrease dominated in UP. The early sowing practice of the farmers of the Punjab and Haryana may be one of the adaptation strategies to manage the terminal heat stress in reproductive stage of the crop in the region. The change-point occurred in late 1990s (1998–2000) in Punjab and Haryana, while in eastern UP it was in early 1990s (1990–1995). Despite the difference in temporal aggregation and spatial resolution, both the datasets yielded similar trends, confirming both the robustness of the results and applicability of the datasets over the region. The results demands further research for proper attribution of the effects into its causes and may help devising crop adaption practices to climatic stresses.     

Mountains as vulnerable places: a global synthesis of changing mountain systems in the Anthropocene

GeoJournal - This article provides a comprehensive review of mountains as a highly heterogeneous, dynamic, yet increasingly vulnerable terrestrial environment undergoing rapid change in the...     

Carbonate Alkalinity Enhances Triclosan Photolysis

Triclosan (TCS) is an antimicrobial compound found in many household products used across the world. TCS is not completely removed in wastewater systems, resulting in trace-level concentrations present ubiquitously in surface waters. The direct photodegradation of TCS has been widely studied, with results indicating that TCS breaks down to chlorophenols and dioxins. To date, no studies have specifically investigated the effects of alkalinity on the photolysis of the acidic form of TCS. This study assessed the effect of carbonate/bicarbonate alkalinity, which is ubiquitous in natural waters, on the photolysis rate of TCS. Results indicate that bicarbonate enhances the photodegradation of TCS at pH values well below the pK_a of TCS (7.9), with direct photolysis reaction kinetics that are very slow in the absence of buffers, but significant in the presence of bicarbonate (0.711 h^?1 at pH 6.55). At pH values well above its pK_a, both unbuffered- and buffered-mediated photolysis increased dramatically (1.92 h^?1 for direct photolysis and 2.86 h^?1 in buffered water) and is attributable to the increased photoreactivity of TCS by its conjugate base. Photolysis of methyl triclosan (MeTCS), a non-acidic analog of TCS, demonstrated the importance of TCS’s acidic functionality as MeTCS did not degrade at any pH. The observed influence of alkalinity on the acidic form of TCS photolysis was attributed to both a decrease in its excited state pK_a, coupled with TCS deprotonation through an excited state proton transfer to a base (bicarbonate and to a lesser degree hydrogen phosphate) resulting in the more photo-labile conjugate base form of TCS.

     

A class of solutions for anisotropic stars admitting conformal motion

We provide a new class of interior solutions for anisotropic stars admitting conformal motion. The Einstein’s field equations in this construction are solved for specific choices of the density/mass functions. We analyze the behavior of the model parameters like radial and transverse pressures, density and surface tension.     

On the role of cloud adjustment time scale in simulating precipitation with Relaxed Arakawa–Schubert convection scheme

The precipitation by Relaxed Arakawa–Schubert cumulus parameterization in a General Circulation Model (GCM) is sensitive to the choice of relaxation parameter or specified cloud adjustment time scale. In the present study, we examine sensitivity of simulated precipitation to the choice of cloud adjustment time scale (τ_adj) over different parts of the tropics using National Center for Environmental Prediction (NCEP) Seasonal Forecast Model (SFM) during June–September. The results show that a single specified value of τ_adj performs best only over a particular region and different values are preferred over different parts of the world. To find a relation between τ_adj and cloud depth (convective activity) we choose six regions over the tropics. Based on the observed relation between outgoing long-wave radiation and τ_adj,?we propose a linear cloud-type dependent relaxation parameter to be used in the model. The simulations over most parts of the tropics show improved results due to this newly formulated cloud-type dependent relaxation parameter.     

The Mechanism of the 20°C Isotherm Depth Oscillations for the Bay of Bengal

The monthly variation of thermocline depth in terms of 20°C isotherm depth (Z20) in the Bay of Bengal has been studied using SODA and ARGO datasets. During a southwest monsoon, the Bay of Bengal is deepest in the western basin and shallowest in the eastern basin while it is the opposite during northeast monsoon. The Z20 oscillation is not only affected by semiannual reversing wind forcing but also influenced by coastal Kelvin waves from the eastern coast and remote effect from the Northern Indian Ocean and Malacca Strait. A linear relationship between SSHA and Z20 has been found from both SODA and observational studies.     

Propagation of axi-symmetric relativistic shock waves

Solutions in series for the propagation of relativistic shock waves with axial symmetry are obtained in this paper. We assume that the gaseous elements move almost radially and that the disturbance moves through a cold gas at rest wherein the nucleon number density and the energy density obey an exponential law of distance from a given plane. The motion is sustained by continuous explosions in the central region liberating energy varying as the cube of time. Also, we assume the equation of state of the moving elements as that of photonic gas.     

Propagation of cylindrical relativistic shock waves in the presence of a magnetic field

In this paper we obtain similarity solutions for the propagation of cylindrical relativistic shock waves in the presence of a constant azimuthal magnetic field or in its absence for the medium, where the nucleon number density is uniform. The shock surface moves with constant velocity and the total energy of the disturbance is dependent on time. The solutions are applicable only to an isothermal medium or a cold gas.     

General relativistic study of perfect fluid disk in linearised kerr geometry

In this chapter we present a detailed general relativistic formulation for the study of structure of perfect fluid disk rotating around Kerr black hole. This revised version was published online in July 2006 with corrections to the Cover Date.     

Nonlinear propagation of whistlers in the ionosphere

In this paper, the nonlinear dispersion relation for whistlers in the ionosphere has been derived and then the group travel time for an ion-cyclotron whistler from its source to an observer at the satellite has been theoretically calculated. It is seen that the nonlinear effect has some important contribution in the expression of group travel time. Our present analysis gives a more correct result than that obtained by Gurnett and others. From numerical estimations, it is found that the group travel time of whistler may be changed reasonably due to nonlinear interaction of the wave and the plasma of ionosphere.