Solar cycle variation and N-S asymmetry of λ 5303 coronal intensity     

P. N. Pathak 《Solar physics》1972,25(2):489-492

It is shown that during the present solar cycle (No-20), the 5303 coronal intensity at heliographic latitudes between 15°–40° in both hemispheres had two maxima. The first maximum occurred in 1967–68 and the second in 1969–70. At lower latitudes ( ± 10°) there was only one clear maximum in 1970. These results are in good agreement with those of Gnevyshev (1967) for the previous solar cycle. The North-South asymmetry of 5303 intensity for the period 1957–1970 is studied and its implications to solar-terrestrial relationships are discussed. It is shown that during the period studied, the N-S asymmetry of 5303 intensity is negatively correlated with sunspot activity.  相似文献   

Correlation of solar wind velocity with λ 5303 coronal intensity     

P. N. Pathak 《Solar physics》1971,20(2):462-473

Using solar wind velocity data obtained by Mariner-2 and IMP-1 spacecrafts, an attempt has been made to study its correlation with 5303 coronal intensity. It is shown that the long-lasting regions of enhanced 5303 intensity in the solar corona are well correlated with recurrent streams of solar wind having high velocity. The time-lag between the central meridian passage (CMP) of the coronal features and the detection of the solar wind streams at the spacecraft is found to be smaller than that implied by a radial solar wind. Significant positive correlations for Mariner-2 data are obtained for coronal intensity at heliolatitudes 5°S–10°N with a time-lag of + 2 days while for IMP-1 data, high positive correlations are obtained for the southern heliolatitudes (10°–25°S) without any time-lag. It should be noted that the average heliographic latitudes for Mariner-2 and IMP-1 were 4°N and 4°S respectively during the periods covered by the present analysis. The implications of the results are discussed.Presented at IUCSTP Symposium on Solar-Terrestrial Physics, Leningrad, May 1970.  相似文献   

Slow growing towns in India     

Pathak P 《Population geography : a journal of the Association of Population Geographers of India》1986,8(1-2):64-75

Some variation in the growth rates of towns is more or less a universally accepted phenomenon. But why some towns are not even able to sustain the population added due to natural increase in an overall rapidly urbanizing environment is the central theme of this paper. An analysis of slow growing towns in India, conducted at both macro- and micro-levels, reveals that 1) the slow growing towns are concentrated in a few states which are characterized by a high urbanization level; 2) practically all of them have suffered net out-migration, barring those whose slow growth was due to reduction in the territorial jurisdiction; and 3) their slow growth is attributed to a low administrative status, poor transport, connectivity, inadequate developmental efforts, and the fast growth of nearby towns. (author's)  相似文献   

Eco-restoration of a high-sulphur coal mine overburden dumping site in northeast India: A case study   总被引：1，自引：0，他引：1  

J. Dowarah  H. P. Deka Boruah  J. Gogoi  N. Pathak  N. Saikia  A. K. Handique 《Journal of Earth System Science》2009,118(5):597-608

Eco-restoration of mine overburden (OB) or abandoned mine sites is a major environmental concern. In the present investigation, an integrated approach was used to rejuvenate a high-sulphur mine OB dumping site in the Tirap Collieries, Assam, India, which is situated in the Indo-Burma mega-biodiversity hotspot. A mine OB is devoid of true soil character with poor macro and micronutrient content and contains elevated concentrations of trace and heavy metals. Planting of herbs, shrubs, cover crops and tree species at close proximity leads to primary and secondary sere state succession within a period of 3 to 5 years. A variety of plant species were screened for potential use in restoration: herbs, including Sccharum spontaneum, Cymbopogon winterianus Jowitt (citronella), and Cymbopogon flexuosus (lemon grass) cover plants, including Mimosa strigillosa, M. striata, and M. pigra; shrubs, including Sesbania rostrata (dhaincha) and Cassia streata (cassia); and tree species, including Gmelina arborea (gomari) and Dalbergia sissoo (sissoo). Amendment with unmined soil and bio-organic matter was required for primary establishment of some plant species. Management of these plant species at the site will ensure long term sustainable eco-restoration of the coal mine-degraded land.  相似文献   

Role of 3d-dispersive Alfven waves in coronal heating     

R. P. Sharma  N. Yadav  N. Pathak 《Astrophysics and Space Science》2014,351(1):75-80

Coronal heating is one of the unresolved puzzles in solar physics from decades. In the present paper we have investigated the dynamics of vortices to apprehend coronal heating problem. A three dimensional (3d) model has been developed to study propagation of dispersive Alfvén waves (DAWs) in presence of ion acoustic waves which results in excitation of DAW and evolution of vortices. Taking ponderomotive nonlinearity into account, development of these vortices has been studied. There are observations of such vortices in the chromosphere, transition region and also in the lower solar corona. These structures may play an important role in transferring energy from lower solar atmosphere to corona and result in coronal heating. Nonlinear interaction of these waves is studied in view of recent simulation work and observations of giant magnetic tornadoes in solar corona and lower atmosphere of sun by solar dynamical observatory (SDO).  相似文献   

Multifractality due to long-range correlation in the L-band ionospheric scintillation S 4 index time series     

H. J. Tanna  K. N. Pathak 《Astrophysics and Space Science》2014,350(1):47-56

The earth’s ionosphere is well recognized as a dynamical system and non-linearly coupled with the magnetosphere above and natural atmosphere below. The shape and time variability of the ionosphere indeed shows chaos, pattern formation, random behaviour and self-organization. The present paper studies the propriety of Multifractal Detrended Fluctuation Analysis (MF-DFA) technique for the ionospheric scintillation index time series. MF-DFA is used to identify the scaling behaviour of the ionospheric scintillation time-series data of two different nature. The obtained results show the robustness and the relevancy of the MF-DFA technique for the ionospheric scintillation index time series. The comparison of the MF-DFA results of original data to those of shuffled and surrogate series shows that the multifractal nature of considered time-series is almost due to long-range correlations. Subsequently, the Hurst exponents derived from two parallel methods namely Rescaled range analysis (R/S) and Auto Correlation Function (ACF) are also suggesting the presence of long range correlation. The presented results in this work may be of assistance for future modeling and simulation studies.  相似文献