Variations in p-mode Parameters and Sub-surface Flows of Active Regions with Flare Activity

We examine the characteristic properties of photospheric p-modes and sub-photospheric flows of active regions (ARs) observed during the period of 26-31 October 2003. Using ring diagram analysis of Doppler velocity data obtained from the Global Oscillations Network Group (GONG), we have found that p-mode parameters evolve with ARs and show a strong association with flare activity. Sub-photospheric flows, derived using inversions of p-modes, show strong twist at the locations of ARs, and large variation with flare activity.Comment: 7 pages, 3 figures, to be appear in the ASI Conference Serie

Activity Related Variations of High-Degree p-Mode Amplitude, Width and Energy in Solar Active Regions

We study the properties of high degree p-mode oscillations in flaring and dormant ARs and compare them with those in corresponding quiet regions (QRs) to find the association of mode parameters with magnetic and flare related activities. Our analysis of several flaring and dormant ARs, showed strong association of mode amplitude, width and energy with magnetic and flare activities although their changes are combined effects of foreshortening, filling factor, magnetic activity, flare activity, and measurement uncertainties. We find that the largest decrease in mode amplitude and background power of an AR are caused by the angular distance of the AR from the solar disc centre. After correcting the mode parameters for foreshortening and filling factor, we find that the mode amplitude of flaring and dormant ARs are smaller than in corresponding QRs, and decreases with increasing MAI suggesting a larger mode power suppression in ARs with stronger magnetic fields. The mode widths in ARs are larger than in corresponding QRs and increase with MAI, indicating shorter lifetimes of modes in ARs than in QRs. The largest decrease (increase) in mode amplitude (mode width) of dormant ARs is found in the five minute frequency band. The average mode energy of both the flaring and dormant ARs are smaller than in their corresponding QRs, decreasing with increasing MAI. But the average mode energy decrease rate in flaring ARs are smaller than in dormant ARs. Also, the increase in mode width rate in dormant (flaring) ARs is followed by decrease (increase) in amplitude variation rate. Furthermore, inclusion of mode corrections for MAI shows that mode amplitude and mode energy of flaring ARs increase with FI while mode width shows an opposite trend. The increase (decrease) in mode amplitude (width) is larger in the five minute and higher frequency band. Increase in width variation rate is ..

A Technique for Automated Determination of Flare-ribbon Separation and Energy Release

We present a technique for automatic determination of flare-ribbon separation and the energy released during the course of two-ribbon flares. We have used chromospheric H$\alpha$ filtergrams and photospheric line-of-sight magnetograms to analyse flare-ribbon separation and magnetic-field structures, respectively. Flare-ribbons were first enhanced and then extracted by the technique of "region growing", i.e., a morphological operator to help resolve the flare-ribbons. Separation of flare-ribbons was then estimated from magnetic polarity reversal line using an automatic technique implemented into Interactive Data Language (IDL\tm) platform. Finally, the rate of flare-energy release was calculated using photospheric magnetic-field data and the corresponding separation of the chromospheric H$\alpha$ flare-ribbons. This method could be applied to measure the motion of any feature of interest (e.g., intensity, magnetic, Doppler) from a given point of reference.Comment: 20 pages, 7 figure

On the injection of helicity by shearing motion of fluxes in relation to Flares and CMEs

An investigation of helicity injection by photospheric shear motions is carried out for two active regions(ARs), NOAA 11158 and 11166, using line-of-sight magnetic field observations obtained from the Helioseismic and Magnetic Imager on-board Solar Dynamics Observatory. We derived the horizontal velocities in the active regions from the Differential Affine Velocity Estimator(DAVE) technique. Persistent strong shear motions at the maximum velocities in the range of 0.6--0.9km/s along the magnetic polarity inversion line and outward flows from the peripheral regions of the sunspots were observed in the two active regions. The helicities injected in NOAA 11158 and 11166 during their six days' evolution period were estimated as $14.16\times10^{42}$Mx$^2$ and $9.5\times10^{42}$Mx$^2$, respectively. The estimated injection rates decreased up to 13% by increasing the time interval between the magnetograms from 12 min to 36 min, and increased up to 9% by decreasing the DAVE window size from $21\times18$ to $9\times6$ pixel$^2$, resulting in 10% variation in the accumulated helicity. In both ARs, the flare prone regions (R2) had inhomogeneous helicity flux distribution with mixed helicities of both signs and that of CME prone regions had almost homogeneous distribution of helicity flux dominated by single sign. The temporal profiles of helicity injection showed impulsive variations during some flares/CMEs due to negative helicity injection into the dominant region of positive helicity flux. A quantitative analysis reveals a marginally significant association of helicity flux with CMEs but not flares in AR 11158, while for the AR 11166, we found marginally significant association of helicity flux with flares but not CMEs, providing evidences of the role of helicity injection at localized sites of the events.Comment: In press, Ap

Evaluation of thiamethoxam 70% WS as seed treatment against early sucking pests of tomato

The present investigation was carried out at Vegetable Research Centre, G. B. Pant University of Agriculture and Technology, Pantnagar, Uttarakhand during the 2013 and 2014 to evaluate the effectiveness of thiamethoxam, used as seed treatment against the sucking insects of tomato. The seed treatment with thiamethoxam protected tomato seedlings from aphids and thrips at the early season from the onset of seed planting. There was a fast initial effect against the pests then gradually decreased to reach a moderate effect. Data revealed that Thiamethoxam 70% WS @ 4.2 g a.i./kg of seed showed the significant pest reduction followed by Thiamethoxam 70% WS @ 3.85 g a.i./kg of seed. Highest yield was recorded by Thiamethoxam 70% WS @ 4.2 g a.i./kg of seed (28.25 t/ha) closely followed by Thiamethoxam 70% WS @ 3.85 g a.i./kg of seed (25.00 t/ha) as compared to untreated check (20.91t/ha). Percent increase in yield over control was highest (35.10%) in Thiamethoxam 70% WS @ 4.2 g a.i./kg of seed followed by Thiamethoxam 70% WS @ 3.85 g a.i./kg of seed (19.56%). The percent reductions of predators by Thiamethoxam, used as seed treatment, in both the seasons ranged from 1.65- 2.58% which was very minimum. Hence, it was concluded that the seed treatment of tomato with Thiamethoxam 70% WS @ 4.20 g a.i/kg of seed reduced the early season insect-pests (aphid and thrips) and had very less effect of natural enemies population ascompared to control and also increased the fruit yield significantly than other treatments