Experimental Seasonal Forecast of Monsoon 2005 Using T170L42 AGCM on PARAM Padma

As a part of the Experimental Extended Range Monsoon Prediction Experiment, ensemble mode seasonal runs for the monsoon season of 2005 were made using the National Centre for Environmental Prediction (NCEP), T170L42 AGCM. The seasonal runs were made using six initial atmospheric conditions based on the NCEP operational analysis and with forecast monthly sea-surface temperature (SST) of the NCEP Coupled forecast system (CFS). These simulations were carried out on the PARAM Padma supercomputer of Centre for Development of Advanced Computing (C-DAC), India. The model climatology was prepared by integrating the model for ten years using climatological SST as the lower boundary. The climatology of the model compares well with the observed, in terms of the spatial distribution of rainfall over the Indian land mass. The model-simulated rainfall compares well with the Tropical Rainfall Measuring Mission (TRMM) estimates for the 2005 monsoon season. Compared to the model climatology (7.81 mm/day), the model had simulated a normal rainfall (7.75 mm/day) for the year 2005 which is in agreement with the observations (99% of long-term mean). However, the model could not capture the observed increase in September rainfall from that of a low value in August 2005. The circulation patterns simulated by the model are also comparable to the observed patterns. The ensemble mean onset is found to be nearer to the observed onset date within one pentad.     

Quantification of suspended solids in Dal lake,Srinagar using remote sensing technology

Indian Remote Sensing satellite (IRS)-1B, Linear Imaging Self Scanner (LISS)-II spectral digital data was analysed to determine the feasibility of quantifying the concentration of suspended solids in the surface water of inland water body, Dal lake, in Srinagar, India. The water samples collected in concurrent with IRS-1B overpass, were analysed to determine the concentration of suspended solids. The results indicate that a positive functional relationship exist between the concentration of suspended solids and the visible wave length bands 1 and 3 and near infrared band 4. It has been observed that as the concentration of suspended solids increase, the spectral response also increases. It is concluded that IRS LISS-H data can be effectively used to quantify suspended sediment concentration in the Dal lake surface water.     

Delineation of shallow Deccan basaltic aquifers from Maharashtra using aerial photointerpretation

The Deccan basaltic lava flows form shallow unconfined aquifers tapped for irrigation by large diameter dugwells. Aerial photographs form an important utility in the hydrogeological mapping of these shallow basaltic aquifers. Aerial photographs provide extensive information regarding the agricultural landuse in the agricultural sector from the Deccan basaltic terrain of Maharashtra. A zonation based on the cultivation, patterns brings out, quite clearly, the relationship between the agriculture in the area and the irrigation potential of the aquifer(s). This, relationship itself points to the inherent heterogeneity of the Deccan basaltic aquifers. Cultivation patterns/signatures that emerge through aerial photointerpretation can form the basis for a systematic hydrogeological mapping leading to aquifer characterisation of Deccan basalts, especially in regions where rock surfaces are not, directly exposed (such as is evident in many agricultural belts of Maharashtra state).     

Stochastic finite-fault modeling of M w 5.4 earthquake along Uttarakhand–Nepal border

Natural Hazards - In this work, an attempt has been made to simulate strong ground motion of M w 5.4 earthquake in Kumaun region of Uttarakhand. The simulation is based on modified stochastic...     

Reducing errors in the GRACE gravity solutions using regularization

The nature of the gravity field inverse problem amplifies the noise in the GRACE data, which creeps into the mid and high degree and order harmonic coefficients of the Earth’s monthly gravity fields provided by GRACE. Due to the use of imperfect background models and data noise, these errors are manifested as north-south striping in the monthly global maps of equivalent water heights. In order to reduce these errors, this study investigates the use of the L-curve method with Tikhonov regularization. L-curve is a popular aid for determining a suitable value of the regularization parameter when solving linear discrete ill-posed problems using Tikhonov regularization. However, the computational effort required to determine the L-curve is prohibitively high for a large-scale problem like GRACE. This study implements a parameter-choice method, using Lanczos bidiagonalization which is a computationally inexpensive approximation to L-curve. Lanczos bidiagonalization is implemented with orthogonal transformation in a parallel computing environment and projects a large estimation problem on a problem of the size of about 2 orders of magnitude smaller for computing the regularization parameter. Errors in the GRACE solution time series have certain characteristics that vary depending on the ground track coverage of the solutions. These errors increase with increasing degree and order. In addition, certain resonant and near-resonant harmonic coefficients have higher errors as compared with the other coefficients. Using the knowledge of these characteristics, this study designs a regularization matrix that provides a constraint on the geopotential coefficients as a function of its degree and order. This regularization matrix is then used to compute the appropriate regularization parameter for each monthly solution. A 7-year time-series of the candidate regularized solutions (Mar 2003–Feb 2010) show markedly reduced error stripes compared with the unconstrained GRACE release 4 solutions (RL04) from the Center for Space Research (CSR). Post-fit residual analysis shows that the regularized solutions fit the data to within the noise level of GRACE. A time series of filtered hydrological model is used to confirm that signal attenuation for basins in the Total Runoff Integrating Pathways (TRIP) database over 320 km radii is less than 1 cm equivalent water height RMS, which is within the noise level of GRACE.     

Disposition and metabolism of 2,3,7,8-tetrachlorodibenzofuran (TCDF) in rainbow trout

In order to elucidate the metabolic fate of 2,3,7,8-tetrachlorodibenzofuran (TCDF) in fish and to thereby facilitate the assessment of the risks posed by this environmental toxin, we determined the whole body half-life, tissue distribution and metabolism of [³H TCDF in rainbow trout (Onchorynchus mykiss), treated orally. A whole body biphasic elimination pattern resulted in the excretion of 60% of the administered chemical during the first 3 days, after which a much slower elimination-rate (half-life = 14 days) was observed. Significant amounts of water-soluble metabolites were found in both bile and liver. Of the TCDF-derived radioactivity in bile, approximately 50% represented glucuronide conjugates, predominantly 4-hydroxy-2,3,7,8-TCDF: substantial amounts of the sulfate conjugate of this same metabolite were also present. Except at early time points, muscle contained the predominant fraction of TCDF-derived radioactivity, amounting to 25–65% of the total radioactivity present in the fish. More than 95% of the radioactivity present in muscle represented unmetabolized TCDF.