Impacts of future Indian greenhouse gas emission scenarios on projected climate change parameters deduced from MAGICC model

The MAGICC (Model for the Assessment of Greenhouse gas Induced Climate Change) model simulation has been carried out for the 2000–2100 period to investigate the impacts of future Indian greenhouse gas emission scenarios on the atmospheric concentrations of carbon dioxide, methane and nitrous oxide besides other parameters like radiative forcing and temperature. For this purpose, the default global GHG (Greenhouse Gases) inventory was modified by incorporation of Indian GHG emission inventories which have been developed using three different approaches namely (a) Business-As-Usual (BAU) approach, (b) Best Case Scenario (BCS) approach and (c) Economy approach (involving the country’s GDP). The model outputs obtained using these modified GHG inventories are compared with various default model scenarios such as A1B, A2, B1, B2 scenarios of AIM (Asia-Pacific Integrated Model) and P50 scenario (median of 35 scenarios given in MAGICC). The differences in the range of output values for the default case scenarios (i.e., using the GHG inventories built into the model) vis-à-vis modified approach which incorporated India-specific emission inventories for AIM and P50 are quite appreciable for most of the modeled parameters. A reduction of 7% and 9% in global carbon dioxide (CO₂) emissions has been observed respectively for the years 2050 and 2100. Global methane (CH₄) and global nitrous oxide (N₂O) emissions indicate a reduction of 13% and 15% respectively for 2100. Correspondingly, global concentrations of CO₂, CH₄ and N₂O are estimated to reduce by about 4%, 4% and 1% respectively. Radiative forcing of CO₂, CH₄ and N₂O indicate reductions of 6%, 14% and 4% respectively for the year 2100. Global annual mean temperature change (incorporating aerosol effects) gets reduced by 4% in 2100. Global annual mean temperature change reduces by 5% in 2100 when aerosol effects have been excluded. In addition to the above, the Indian contributions in global CO₂, CH₄ and N₂O emissions have also been assessed by India Excluded (IE) scenario. Indian contribution in global CO₂ emissions was observed in the range of 10%–26%, 6%–36% and 10%–38% respectively for BCS, Economy and BAU approaches, for the years 2020, 2050 and 2100 for P50, A1B-AIM, A2-AIM, B1-AIM & B2-AIM scenarios. CH₄ and N₂O emissions indicate about 4%–10% and 2%–3% contributions respectively in the global CH₄ and N₂O emissions for the years 2020, 2050 and 2100. These Indian GHG emissions have significant influence on global GHG concentrations and consequently on climate parameters like RF and ∆T. The study reflects not only the importance of Indian emissions in the global context but also underlines the need of incorporation of country specific GHG emissions in modeling to reduce uncertainties in simulation of climate change parameters.     

Hydrologic simulation approach for El Niño Southern Oscillation (ENSO)-affected watershed with limited raingauge stations

ABSTRACT

Since the performance of hydrological models relies on numerous factors, the selection of an appropriate modeling approach for hydrological study has always been a crucial issue. The major objective of this research is to demonstrate that data-driven models such as the Adaptive Neuro-Fuzzy Inference system (ANFIS) are more suitable in a region where spatially distributed precipitation datasets are not available. Since precipitation has a teleconnection with the El Niño Southern Oscillation (ENSO) in different parts of the world, the sea surface temperatures (SSTs) and sea level pressures (SLPs) of the equatorial Pacific can be expected to act as surrogates for the precipitation if there are insufficient raingauge stations in the watershed. Moreover, in contrast to conceptual and physically-based models, data driven models can incorporate SST and SLP in their input vectors, and hence additional forcing of SST with precipitation has been experimented with in past studies. Therefore, our second objective is to test whether the additional forcing of SST and SLP will improve the hydrologic simulation. For this, various ANFIS models for the winter season were developed considering 10 raingauge stations situated at various locations in the watershed. Rainfall from each raingauge station was considered in the ANFIS model one at a time with and without SST/SLP. The results show that the performance of the ANFIS model improved with the additional fusion of SST and SLP, especially when a raingauge station from a remote location was considered. However, this improvement was observed when the analysis was primarily focused on the winter season which is a period with a strong ENSO signal.

Editor D. Koutsoyiannis Associate editor L. See     

Interpreting characteristic drainage timescale variability across Kilombero Valley,Tanzania

We explore seasonal variability and spatiotemporal patterns in characteristic drainage timescale (K) estimated from river discharge records across the Kilombero Valley in central Tanzania. K values were determined using streamflow recession analysis with a Brutsaert–Nieber solution to the linearized Boussinesq equation. Estimated K values were variable, comparing between wet and dry seasons for the relatively small catchments draining upland positions. For the larger catchments draining through valley bottoms, K values were typically longer and more consistent across seasons. Variations in K were compared with long‐term averaged, Moderate‐resolution Imaging Spectroradiometer‐derived monthly evapotranspiration. Although the variations in K were potentially related to evapotranspiration, the influence of data quality and analysis procedure could not be discounted. As such, even though recession analysis offers a potential approach to explore aquifer release timescales and thereby gain insight to a region's hydrology to inform water resources management, care must be taken when interpreting spatiotemporal shifts in K in connection with process representation in regions like the Kilombero Valley. © 2014 The Authors. Hydrological Processes published by John Wiley & Sons Ltd.     

Spinel Ferrite Mediated Photo‐Fenton Degradation of Phenolic Analogues: A Detailed Study Employing Two Distinct Inorganic Oxidants

The present work demonstrates the applicability of ferrites as photo‐Fenton catalysts for deterioration of different phenolic derivatives. To analyze optimal reaction conditions, experiments are performed with four magnetic spinel ferrites MFe₂O₄ (M = Co, Cu, Ni, and Zn) and two inorganic oxidants, i.e., hydrogen peroxide (HP) and potassium peroxymonosulfate (PMS). The reactions are performed using p‐nitrophenol as phenolic probe. CuFe₂O₄ and CoFe₂O₄ possessed excellent ability to activate HP and PMS, respectively, among all four synthesized catalysts. A noteworthy aspect of two oxidizing agents is that the concentration of PMS used during the reaction is four times less than HP. Further, the broad pH activity of PMS provides a significant advantage over HP. The optimal reaction conditions, when HP is the oxidant in the photo‐Fenton degradation, are 0.50 g L^?1 MFe₂O₄, pH 2.5, and 8.8 mM HP. Although PMS is active in a wide pH range (2–10), adequate reaction conditions are 0.50 g L^?1 MFe₂O₄, natural pH, and 2.2 mM PMS. The photo‐Fenton activity of ferrites is extended to the degradation of different nitro‐ and chloro‐analogs of phenol (2‐nitrophenol, 3‐nitrophenol, 4‐nitrophenol, 2,4‐dinitrophenol, 2,4,6‐trinitrophenol, 2‐chlorophenol, 3‐chlorophenol, 4‐chlorophenol, 2,4‐dichlorophenol) with only two ferrites (CuFe₂O₄ and CoFe₂O₄). A comparative study is performed with the two oxidants (HP and PMS) with positive results. Finally, stability and reusability of magnetic ferrites as catalysts are also studied to prove their use in phenolic solution treatment.     

Early Neogene Radiolarian faunal turnover in the northern Indian Ocean: Evidence from Andaman-Nicobar

Two intervals of faunal turnover are revealed by the study of radiolarians from the Early to Middle Miocene sequence of Andaman-Nicobar belonging to Stichocorys wolffii-Calocycletta costata-Dorcadospyris alata zones. These faunal changes are reflected in the values of species diversity, change in abundance of taxa, origination and extinction events and change in radiolarian assemblages. One such faunal change is identified in the latest Early Miocene. The time of this faunal change is marked by the extinction of species like Carpocanopsis cingulata and appearance of Calocycletta costata, Giraffospyris toxaria, Acrocubus octopylus and Liriospyris parkerae, an increasing trend in percentage of cold water species and a decreasing trend in species diversity upwards. The interval coincides with the time of initiation of cooling of sea surface water. Another, and the most prominent faunal turnover of radiolarians is recognized in the Middle Miocene Dorcadospyris alata Zone at about 14.8–12.7 Ma and is characterized by almost complete disappearance of an earlier dominant assemblage and an increase in abundance of an assemblage that was practically absent in the older sequence. The time of this turnover can be correlated with the time of Middle Miocene cooling identified in the examined sequence.     

Appraisal of equivalence and suppression problems in 1D EM and DC measurements using global optimization and joint inversion*

Global optimization with very fast simulated annealing (VFSA) in association with joint inversion is performed for 1D earth structures. The inherent problems of equivalence and suppression in electromagnetic (EM) and direct current (DC) resistivity methods are studied. Synthetic phase data from multifrequency sounding using a horizontal coplanar coil system and synthetic apparent resistivity data from Schlumberger DC resistivity measurements are inverted individually and jointly over different types of layered earth structures. Noisy data are also inverted. The study reveals that global optimization of individual data sets cannot solve inherent equivalence or suppression problems. Joint inversion of EM and DC measurements can overcome the problem of equivalence very well. However, a suppression problem cannot be solved even after combination of data sets. This study reveals that the K-type earth structure is easiest to resolve while the A-type is the most difficult. We also conclude that the equivalence associated with a thin resistive layer can be resolved better than that for a thin conducting layer.     

Plane failure analysis of rock slopes

Summary Hoek and Bray (1981) gave an analytical approach for plane failure analysis for rock slopes that is limited to those slopes in which the upper slope surface is horizontal and the tension crack is vertical. An analysis is presented here which can take these factors into account. It is found that varying the angle of the upper slope from 0° to 30° causes a significant reduction in the factor of safety. Varying the tension crack from vertical to 70° only has an effect when the upper slope angle is less than 20°.     

High energy X-γ ray spectrometer on the Chandrayaan-1 mission to the Moon

The Chandrayaan-1 mission to the Moon scheduled for launch in late 2007 will include a high energy X-ray spectrometer (HEX) for detection of naturally occurring emissions from the lunar surface due to radioactive decay of the²³⁸U and²³²Th series nuclides in the energy region 20–250 keV. The primary science objective is to study the transport of volatiles on the lunar surface by detection of the 46.5 keV line from radioactive²¹⁰Pb, a decay product of the gaseous²²²Rn, both of which are members of the²³⁸U decay series. Mapping of U and Th concentration over the lunar surface, particularly in the polar and U-Th rich regions will also be attempted through detection of prominent lines from the U and Th decay series in the above energy range. The low signal strengths of these emissions require a detector with high sensitivity and good energy resolution. Pixelated Cadmium-Zinc-Telluride (CZT) array detectors having these characteristics will be used in this experiment. Here we describe the science considerations that led to this experiment, anticipated flux and background (lunar continuum), the choice of detectors, the proposed payload configuration and plans for its realization     

Effect of initial stress on reflection at the free surface of anisotropic elastic medium

The propagation of plane waves is considered in a general anisotropic elastic medium in the presence of initial stress. The Christoffel equations are solved into a polynomial of degree six. The roots of this polynomial represent the vertical slowness values for the six quasi-waves resulting from the presence of a discontinuity in the medium. Three of these six values are identified with the three quasi-waves traveling in the medium but away from its boundary. Reflection at the free plane surface is studied for partition of energy among the three reflected waves. For post-critical incidence, the reflected waves are inhomogeneous (evanescent) waves. Numerical examples are considered to exhibit the effects of initial stress on the phase direction, attenuation and reflection coefficients of the reflected waves. The phase velocities and energy shares of the reflected waves change significantly with initial stress as well as anisotropic symmetry. The presence of initial stress, however, has a negligible effect on the phase directions of reflected waves.     

Stability investigation of hill cut soil slopes along National highway 222 at Malshej Ghat,Maharashtra

The section of about 12 km of National highway 222 passing through the Malshej Ghat experience frequent slope failure due to complex geological condition, heavy rainfall and slope geometry. The area is part of Western Ghat Deccan trap and slope masses are made of basalt and its weathered crust (debris/soil). The soil slope failure problem mainly occur in rainy seasons due to induced pore water pressure and reduced strength of the slope mass. The present study has been carried out to investigate the slope forming material and assess the stability of soil slopes by numerical approach. For the identification of the vulnerable zones, field study has been carried out and five vulnerable soil slopes identified namely MGS1, MGS2, MGS3, MGS4 and MGS5 on the basis of degree of weathering and slope geometry. The laboratory experiments were carried out to determine the strength properties of the geomaterials. All the input variables acquired from the field and laboratory experiments have been used for numerical simulation, which was performed with the help of limit equilibrium method (LEM) and finite element method (FEM). Numerical analysis provides understanding of the slope behaviour and illustrates that MGS1 and MGS3 are stable slopes, MGS2 and MGS4 are critically stable, whereas, slope MGS5 is unstable. This study recommend the protection of soil slopes and suggest that more detailed investigation is required for long term remedial measures to prevent risk of damage in Malshej Ghat.