Measurement of Kodaikanal white-light images – VI. Variation of Rotation Rate with Age of Sunspot Groups

We find from an analysis of the Kodaikanal sunspot group data that the rotation rates of spot groups increase with their age when the rotation rates are computed after sorting the spot groups life-span-wise. We confirm these findings from an analysis of the Mt. Wilson sunspot data set too. We show that this trend is in good agreement with the internal rotation profiles from helioseismology (GONG) observations and is also consistent with the concept that the footpoints of the magnetic loops of spot groups are initially anchored in the deeper layers in the solar interior and rise to shallower layers as the spots age, and that the spots reflect the rotation rates at the respective depths at which their footpoints are temporally located. We project the `first-day rotation rates' and the `daily rotation rates' of spot groups on the rotation profiles from the GONG observations and derive the initial anchoring depths of the footpoints of the magnetic loops of the spot groups and their rates of rise as the spot groups age. Our results of the rotation rates are in antithesis to the results reported by investigators from the Greenwich spot group data that show a deceleration in rotation rates as the spot groups age which are also inconsistent with the rotation profiles from helioseismology observations.     

Optical Photometric Observations of γ-Ray Loud Blazars

We report results of our optical photometric observations of ten gammaray loud blazers, namely: 0219 428 (3C66A), PKS 0420-014 (OA 129), S5 0716 714,0754 100 (OI 090.4), 0827 243 (OJ248), 1652 398 (Mrk 501), 2200 420 (BL Lacertae), 2230 114 (CTA 102), 2251 158 (3C 454.3) and 2344 514. The observations were carried out in September-October, 2000 using the 70 cm optical telescope at Abstumani Observatory, Georgia. We found intra-day variations in 0420-014,S5 0716 714, BL Lacertae and CTA 102. A variation of 0.3 magnitude over a timescale of about 3 hours was observed in the R passband in BL Lacertae on JD 2451827.We did not detect any variation in 3C 66A, Mrk 501, or 3C 454.3 during our observations. Nor did we detect any clear evidence of variation in 1ES 2344 514 during our two weeks‘ observing run of the TeV gamma-ray source.     

Radioactivity monitoring in the vicinity of Jawalamukhi thrust NW Himalaya,India for tectonic study

Natural Hazards - This work reports radon-thoron monitoring at two depths (60 and 90 cm) and at 82 sites around Jawalamukhi thrust of NW Himalaya, India using Solid State Nuclear Track...     

Vegetation water content retrieval using scatterometer data at X-band

The vegetation water content (VWC) of kidney bean crop is retrieved using ground-based multi-temporal, multi-angular and co-polarized scatterometer data at X-band. An outdoor crop-bed was prepared to observe the scatterometer response at HH- and VV-polarizations in the angular range from 20° to 70°. The trend of scattering coefficient is found to decrease for the entire angular range. The present study is carried out to investigate the retrieval for VWC of a kidney bean crop at its nine different growth stages by an empirical relation based on least square optimization method using scatterometer data. The results are found promising for the retrieval of the VWC of kidney bean crop at its several growth stages.     

Paleoweathering and Paleoclimatic Reconstructions using Neoproterozoic Paleosol in the Eastern Margin of the Pranhita-Godavari Basin,India

Paleogene sediments of the inner fold belt, Naga hills, have very well preserved ichnofossils. 16 ichnospecies have been documented among 13 ichnogenera such as Arenicolites isp., Chondrites targionii, Cylindrichnus isp., Diplocraterion parallelum, Gyrochorte isp., Ophiomorpha annulata, O. irregulaire, O. nodosa, O. rudis, Palaeophycus tubularis, Planolites beverleyensis, Scolicia palaeobullia, Skolithos linearis, Trypinites weisei, Thalassinoides horizontalis and Zoophycos isp. The ichnofossil assemblages comprise mostly domichnia and fodinichnia benthos of the Skolithos and Cruziana ichnofacies. A shallow marine nearshore to offshore marine environment with fluctuating energy condition has been envisaged.     

Discriminating Tectonic and Magmatic Fabrics in the Remal Granite Gneiss: Implications for Terrane Amalgamation Processes in Southeastern Singhbhum,India

The Remal granite gneiss body in the southeastern part of the Singhbhum Craton, near its contact with the Rengali Province, preserves two orthogonal penetrative foliations. The subhorizontal foliation defines cross and trough bedding structures, and is characterized by (i) systematic grain-size variation between the layers, (ii) the presence of feldspar laths and (iii) graphic intergrowth textures, confirming that it is primary and of igneous origin (S_ign). S_ign has a non-planar geometry and shows a spread in orientations, while a later foliation of tectonic origin is defined by alternating biotite-rich and biotite poor bands that define a consistently oriented gneissic foliation (S₁). S₁ gneissic layering is associated with the alignment of biotite flakes and myrmekite formation, and operated under low grade metamorphic conditions. S1 shows a remarkable similarity in orientation with the shear fabric along the amalgamation front of the Rengali Province with the Eastern Ghats Province further to the south, indicating that strain related to this regional strike-slip event can be identified even in southeastern Singhbhum.     

The study of reflection/transmission phenomena in a corrugated interface between two magnetoelastic transversely isotropic media

In this paper, an integrated approach has been carried out with an intent to study the reflection and transmission phenomena of plane SH-type wave on a corrugated interface separating two magnetoelastic transversely isotropic half-space. Closed form expressions for reflection and transmission coefficients have been derived for both plane and corrugated surface. Rayleigh’s method of approximation have been incorporated to deduce equations for the first- and second-order approximation of corrugation. Analytical solutions for both the half-spaces have been worked out. All possible cases have been apprehended specially for anisotropic and an isotropic medium. The effects of magnetoelastic coupling parameter, angle at which the wave crosses the magnetic field, corrugation amplitude, frequency factor and wave number have been explained by collaborating with graphical analysis.     

Effect of dry sandiness parameter and initial stress on the scattering of plane SH wave

The present paper is incorporated into a mathematical model of transmission and reflection of shear waves through the initially stressed dry sandy medium sandwiched between two initially stressed distinct orthotropic half-spaces. The formulae of transmission and reflection coefficients have been deduced for the propagation of SH waves in the described model subjected to certain boundary conditions applying Snell’s law and Cramer’s method. These coefficients are observed as a function of wave number, phase velocity, initial stress, rigidity, and dry sandiness coefficients. The concepts of energy partition, phase shift, conservation of energy, critical angle, and slowness section are introduced. Graphical approach has been carried out to accomplish a relation between reflection/refraction coefficient, phase shift, and energy ratio with an angle of incidence and wave number on the propagation of shear wave. The study reveals that sandiness parameter, initial stress, and wave number have a cogent respond to the scattering of shear wave that has been illustrated graphically.     

Automated mapping of snow/ice surface temperature using Landsat-8 data in Beas River basin,India, and validation with wireless sensor network data

In this paper, an automated method for retrieval of snow surface temperature (SST) in Beas River Basin, India, using Landsat-8 thermal data is proposed. Digital number (DN) values of thermal data were converted into Top of Atmospheric (TOA) radiance. Surface radiance has been estimated from TOA radiance using a single channel method. The estimated surface radiance was then converted into SST. Cloud free Landsat-8 data for January and February 2017 has been used to estimate SST. Snow and Avalanche Study Establishment (SASE) has established a wireless sensor network (WSN) in an avalanche prone slope in Beas River Basin, India. Landsat-8 retrieved SST has been compared and validated with recorded SST at WSN stations. The retrieved SST using proposed algorithm was in good agreement with SST recorded on ground by sensor network. The mean absolute error (MAE) and root-mean-square error (RMSE) between estimated and recorded SST has been observed as ~?1.1 K and ~?1.5 K for 23 January 2017 and ~?0.7 and ~?1.6 K for 24 February 2017. Algorithm has shown a potential for automated mapping of snow and ice surface temperature using Landsat-8 data for snow cover and glaciers in Himalaya.