NISCAIR Online Periodicals Repository Collection: IJRSP Vol.37(6) [December 2008]

H⍺, EUV and UV analysis of an eruptive 3B/X1.2 flare

Fri, 28 Nov 2008 22:58:59 GMT

Title: H⍺, EUV and UV analysis of an eruptive 3B/X1.2 flare

Authors: Pande, Seema; Pande, Bimal; Uddin, Wahab; Pandey, Kavita

Abstract: The present paper presents observational results of an extremely energetic eruptive flare 3B/X1.2 from superactive region NOAA 10486. The observations were taken on 26 October 2003 with 15 cm Solar Tower Telescope at Aryabhatta Research Institute of Observational Sciences (ARIES). Hα observations of the flare show long multi ribbon eruptions along a large twisted (sigmoid) filament in a high gradient (~90º) magnetic field and shear. The evolution pattern of this flare is similar in EUV and UV. Four eruptive centers or kernels in Hα have been chosen, wherein K₁ shows two prominent peaks while K₃ exhibits only one prominent peak with gradual decay. The analysis shows that this is a classical long duration event (LDE). The results have been discussed in the light of existing theories.

Page(s): 386-390

Geo-effective transients and their solar causes during solar cycle 23

Fri, 28 Nov 2008 22:58:59 GMT

Title: Geo-effective transients and their solar causes during solar cycle 23

Authors: Kumar, Santosh; Kaur, Simranjit

Abstract: During nine-year period of the current solar cycle 23 from July 1996 to January 2005, geomagnetic storms (GMSs) of Intense if (Dst < -100nT), Major if (-50nT ≥ Dst ≥ -100nT) and Minor if (-20nT ≥ Dst ≥ -50nT) have been investigated. It is observed that maximum number of GMSs are associated with coronal mass ejections (CMEs) followed by individual H⍺ and X-ray solar flare events. When accumulated effect of Hα and X-ray solar flare events are considered, these solar flares are better associated with GMSs than CMEs. A significant decline in the number of Intense and Minor GMSs have been observed from 1998 to 1999, however, there is an increase in Major GMSs. On the contrary, during 1997-98, Intense and Minor GMSs have increased with the ascending phase of solar activity and Major GMSs have decreased. It is observed that an overall northern bias apparently prevails for solar flares and active prominences and disappearing filaments. Hα and X-ray solar flares occurring over the western limb of the solar disk cause larger disturbances in magnetosphere leading to occurrence of Intense GMSs, whereas, solar flares occurring on eastern limb of the solar disk lead to occurrence of Major and Minor GMSs. It is observed that coronal intensity (CI) is maximum for Minor GMSs followed by Major and Intense GMSs, whereas, mean CI is maximum for Intense GMSs followed by Major and Minor GMSs. The results show that the product of solar wind velocity (Vsw) with minimum Bz component (Bzmin) of interplanetary magnetic field (Vsw.Bzmin), product of linear velocity of CMEs (Vcme) with Bzmin (Vcme.Bzmin) along with minimum Dst of the sudden storm commencement day are the reliable indicators of intensity of GMSs.

Page(s): 379-385

Size distribution of trace metals in ambient air of Agra

Fri, 28 Nov 2008 22:58:59 GMT

Title: Size distribution of trace metals in ambient air of Agra

Authors: Lakhani, Anita; Parmar, R S; Satsangi, G S; Prakash, Satya

Abstract: Trace metals, viz. Al, Si, Ca, Mg, Fe, Mn, Pb, Ni, V, Cd, Sn, Cr, Cu and Zn were identified in size-fractionated aerosols of urban atmosphere of Agra. The metals that are largely soil derived, e.g. Al, Si, Ca and Mg had highest concentrations and exhibited a bimodal pattern with larger fraction in the coarse mode. Other metals, viz. Fe, Mn, Pb, Ni, V, Cd, Sn, Cr, Cu and Zn were found to dominate in the fine mode consistent with their anthropogenic origin. Source identification has been further confirmed by enrichment factor calculations.

Page(s): 434-442

Chemical composition of rainwater in Panipat, an industrial city in Haryana

Fri, 28 Nov 2008 22:58:59 GMT

Title: Chemical composition of rainwater in Panipat, an industrial city in Haryana

Authors: Tiwari, S; Srivastava, Manoj K; Bisht, Deewan Singh

Abstract: Chemical composition of rainwater at Panipat, an industrial city in India, during the south-west monsoon seasons 2003-2005 has been studied. The collected samples have been analyzed for major anions, cations and pH along with conductivity. The volume weighted pH of rainwater varied from 5.02 to 6.86 with a mean value of 5.51, which is slightly acidic. About 37% of rain samples were observed to be acidic due to high SO₂ emissions from industries. The trend of average ionic concentration in precipitation (μeq/l) showed SO₄²⁻> Ca²⁺> NH₄⁺> Cl⁻> NO₃⁻> Na⁺> Mg²+> F⁻> K⁺ >HCO₃⁻. The percentage contribution to the total ionic concentration is found to be 51% to cations and 49% to anions. Sulphate, calcium and ammonium shared maximum contribution. Major part of sulphate ion in rainwater at Panipat was of anthropogenic origin, i.e. by the oxidation of sulphur dioxide emitted from burning of fossil fuels from thermal power plant, oil refinery, fertilizer plant, etc. The major source of nitrate was biomass burning, automobile and soil. Ammonium in precipitation was due to bacterial action on nitrogen compounds in the soil, urine and from industrial sources. The ratio of sea salt (Na+ and Cl⁻) was equal to the seawater, suggesting that it was mostly influenced by marine air.

Page(s): 443-449