Longitudinal Distribution of Solar Flares and Their Association with Coronal Mass Ejections and Forbush Decreases

Major Hα solar-flare events of high optical importance have been employed to study their heliographic distribution in longitude around the Sun for the period of 2001 to 2006. A statistical analysis was performed to obtain their relationship with halo/partial-halo CMEs and Forbush decreases (Fds) of cosmic-ray intensity. Our analysis indicates that 63% of the solar flares associated with halo CMEs and Fds occur in the western hemisphere and of 37% of such flares occur in the eastern hemisphere. Similarly, we found that nearly 60% of the solar flares associated with partial- halo CMEs and Fds occur in the western hemisphere and the rest (40%) occur in the eastern hemisphere. Finally, we conclude that the flares in association with CMEs and located in the western hemisphere of the solar disk are more effective in producing Fds. The magnitudes of Fds are observed to be higher when in association of halo CMEs. A slight excess in the eastern hemisphere is found for both the halo and partial-halo CMEs.     

Multiwavelength Observations of a Failed Flux Rope in the Eruption and Associated M-Class Flare from NOAA AR 11045

We present the multiwavelength observations of a flux rope that was trying to erupt from NOAA AR 11045 and the associated M-class solar flare on 12 February 2010 using space-based and ground-based observations from TRACE, STEREO, SOHO/MDI, Hinode/XRT, and BBSO. While the flux rope was rising from the active region, an M1.1/2F class flare was triggered near one of its footpoints. We suggest that the flare triggering was due to the reconnection of a rising flux rope with the surrounding low-lying magnetic loops. The flux rope reached a projected height of ≈0.15R _⊙ with a speed of ≈90 km s⁻¹ while the soft X-ray flux enhanced gradually during its rise. The flux rope was suppressed by an overlying field, and the filled plasma moved towards the negative polarity field to the west of its activation site. We found the first observational evidence of the initial suppression of a flux rope due to a remnant filament visible both at chromospheric and coronal temperatures that evolved a couple of days earlier at the same location in the active region. SOHO/MDI magnetograms show the emergence of a bipole ≈12 h prior to the flare initiation. The emerged negative polarity moved towards the flux rope activation site, and flare triggering near the photospheric polarity inversion line (PIL) took place. The motion of the negative polarity region towards the PIL helped in the build-up of magnetic energy at the flare and flux rope activation site. This study provides unique observational evidence of a rising flux rope that failed to erupt due to a remnant filament and overlying magnetic field, as well as associated triggering of an M-class flare.     

Comparison of results of BIS and GSI guidelines on macrolevel landslide hazard zonation — A case study along highway from Bhalukpong to Bomdila,West Kameng district,Arunachal Pradesh

This paper compares the findings of macrolevel landslide hazard zonation carried out along the highway from Bhalukpong to Bomdila, West Kameng district, Arunachal Pradesh following GSI and BIS guidelines. The map resulted from the GSI guideline shows that 69.31% of the faceted area falls under the Low Hazard Zone (LHZ) while 17.69%, 7.31%, 5.03% and 0.65% of the area are in Moderate Hazard Zone (MHZ), High Hazard Zone (HHZ), Very Low Hazard Zone (VLHZ) and Very High Hazard Zone (VHHZ) respectively. Correlation between the landslide incidences and different hazard zones reveals that maximum failure percentage is in VHHZ and it is followed by HHZ, MHZ and LHZ. The second map resulting from BIS guideline reveals that 45.77% of the faceted area falls under MHZ while 41.39%, 11.52% and 1.29% of the area are in HHZ, LHZ and VHHZ respectively. Not a single facet falls in VLHZ.With regard to failure percentage VHHZ experiences 50%, while that of HHZ, MMH and LHZ is roughly 11.5% each. In the study area, the landslide hazard zonation map resulting from GSI guideline broadly conforms to field condition. It may be due to the fact that the study area is along the road corridor where slope cutting and landslides are very common and GSI guideline considers both the slope cutting and landslide parameters, while it is not so in the case of BIS guidelines. However, a final conclusion can be drawn after carrying out such studies in different geological settings.     

Interpretation of the global anisotropy in the radio polarizations of cosmologically distant sources

We present a detailed statistical study of the observed anisotropy in radio polarizations from distant extragalactic objects. This anisotropy was earlier found by Birch (1982) and reconfirmed by Jain and Ralston (1999) in a larger data set. A very strong signal was seen after imposing the cut , whereRM is the rotation measure and its mean value. In this paper, we show that there are several indications that this anisotropy cannot be attributed to bias in the data. We also find that a generalized statistic shows a very strong signal in the entire data without imposing theRM dependent cut. Finally we argue that an anisotropic background pseudoscalar field can explain the observations.     

Cylindrical Zakharov–Kuznestov equation for ion-acoustic waves with electrons featuring non-extensive distribution

Cylindrical Zakharov–Kuznestov equation for ion-acoustic waves comprising of ions and electrons featuring non-extensive distribution are derived from the fluid equations through reductive perturbation technique. System of first order ordinary differential equations is obtained from Zakharov–Kuznestov equation through dynamical system approach and ultimately it is solved using numerical method. It is found that the electron to positron ratio parameter and the non-extensive distributed parameter due to electron play crucial role on the solution.     

Modified Dubois Model for Estimating Soil Moisture with Dual Polarized SAR Data

This paper discusses a new methodology to estimate soil moisture in agriculture region using SAR data with the use of HH and HV polarization. In this study the semi empirical model derived by Dubois et al. (IEEE Transactions on Geoscience and Remote Sensing, 33(4), 915–926, 1995) was modified to work using σ _HH instead of two like polarization equations σ_HH, σ_VV so that soil moisture can be obtained for the larger area frequently. The field derived roughness correlated with the cross polarization ratio (HV/HH) to replace the one unknown parameter ‘s’ in the Dubois model and hence the dielectric constant was derived by inverting the Dubois model equation (HH). The Topp et al. (Water Resources Research, 16(3), 574–582, 1980) model was used to retrieve soil moisture using the dielectric constant. The mid incidence angle was used to overcome the incident angle effect and it worked successfully to the larger extent. The result is realistic overall, especially where surface has less variation in the roughness and vegetation since the penetration capability of C-band is limited when plant grows hence model valid in the initial period of cultivation. The derived model is having good scope for soil moisture monitoring with the present availability of Indian RISAT data.     

Multi isotopic approach to study temporal variation of groundwater quality in coastal aquifer of Saijo plain, Shikoku Island, Japan

In order to delineate geochemical processes and its relation with groundwater quality evolution, hydrochemical and isotopic analysis were carried out in coastal groundwater of Saijo plain, western Japan. From analytical results, even within a small distance from the coast; ionic concentration of water samples varies a lot which infers non-homogenous and patchy distribution of different aquifer system (complex geology). From stable isotopic results, it was found that most of sample points plotted near the local meteoric water line (LMWL) i.e. origin of ground water is meteoric in principle; however point away from the LMWL might favors exchange with rock minerals.