Temporal characteristics of aerosol physical properties at Visakhapatnam on the east coast of India during ICARB — Signatures of transport onto Bay of Bengal     

K. Niranjan  V. Sreekanth  B. L. Madhavan  T. Anjana Devi  B. Spandana 《Journal of Earth System Science》2008,117(1):421-427

Realizing the importance of aerosol physical properties at the adjoining continental and coastal locations in the airmass pathways onto the oceanic region, extensive measurements of aerosol physical properties were made at Visakhapatnam (17.7°N, 83.3°E), an eastern coastal location in peninsular India during the ICARB period. The temporal variations of aerosol optical depth, near surface aerosol mass size distributions and BC mass concentrations show significantly higher aerosol optical depth and near surface mass concentrations during the first and last weeks of April 2007. The mean BC mass fraction in the fine mode aerosol was around 11%. The aerosol back scatter profiles derived from Micro Pulse Lidar indicate a clear airmass subsidence on the days with higher aerosol optical depths and near surface mass fraction. A comparison of the temporal variation of the aerosol properties at Visakhapatnam with the MODIS derived aerosol optical depth along the cruise locations indicates a resemblance in the temporal variation suggesting that the aerosol transport from the eastern coastal regions of peninsular India could significantly affect the aerosol optical properties at the near coastal oceanic regions and that the affect significantly reduced at the farther regions.  相似文献   

Explosive hydrogen-burning model of solar flares     

L. Manihar Singh  L. Randhoni Devi 《Astrophysics and Space Science》1990,172(2):315-316

A model of solar flare is proposed, taking into account the high temperature (10⁹K) produced by the shock wave generated by the hydromagnetic wave at the junction of sunspot and the area just outside it and subsequent explosive hydrogen burning, producing the desired 10^28–29 ergs of a solar flare.  相似文献   

Tectonic forcing of drainages and geomorphic features developed across Himalayan mountain frontal part of western limb of Siang Antiform,Arunachal Himalaya     

R. K. Mrinalinee Devi  S. S. Bhakuni  M. K. Phukan  R. Duarah 《Environmental Earth Sciences》2016,75(5):413

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Quantitative geo-morphometric and land cover-based micro-watershed prioritization in the Tons river basin of the lesser Himalaya     

Pankaj Chauhan  Devi Datt Chauniyal  Nilendu Singh  Reet Kamal Tiwari 《Environmental Earth Sciences》2016,75(6):498

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Strain analysis and stratigraphic status of Nongkhya,Sumer and Mawmaram conglomerates of Shillong basin,Meghalaya, India     

Niva Rani Devi  K. P. Sarma 《Journal of Earth System Science》2010,119(2):161-174

Shillong basin, one of the Purana basins of the Indian peninsula is situated in the central and eastern parts of the Shillong plateau of NE India. Metasedimentary and metavolcanic rocks of the basin are of Mesoproterozoic age and lithostratigraphically belong to Shillong Group (erstwhile Shillong series) comprising Lower Metapelitic Formation (LMF) and Upper Quartzitic Formation (UQF). A long, persistent, faulted and tectonically attenuated conglomerate known as Nongkhya-Sumer-Mawmaram-conglomerate separates these two formations. In the present work, quantitative strain analyses of the pebbles of Sumer, Nongkhya and Mawmaram conglomerates of Ri-Bhoi and West Khasi Hills districts of Meghalaya are carried out using manual and computerized programmes. Eight different techniques for intrapebble, interpebble and bulk rock strain estimation are applied and results are compared systematically. Sumer and Mawmaram conglomerates bear the testimony of broadly flattening type of deformation (0 < k < 1) while Nongkhya conglomerate shows constriction type (1 < k < α). The change in strain ellipsoid shape from Nongkhya to Mawmaram area is accompanied by a change of fabric from S < L to L < S tectonites. Affinity of rotational strain is more in Nongkhya conglomerate as compared to Sumer and Mawmaram conglomerates. The compactness of pebbles is high in case of Nongkhya conglomerate and low to moderate in Sumer and Mawmaram conglomerates indicating high strain in Nongkhya conglomerate (northeastern part of Shillong basin) relative to Sumer and Mawmaram conglomerates (southwestern part of Shillong basin). Thus strain magnitude increases from SW to NE direction of the Shillong basin.  相似文献   

Palaeomagnetism of metadolerite dykes and sills from Proterozoic Shillong basin,NE India: Implications related to the age and magmatism     

K. P. Sarma  M. Venkateshwarlu  S. K. Patil  J. J. Laskar  Niva Rani Devi  J. Mallikharjuna Rao 《Journal of the Geological Society of India》2014,83(2):147-155

The basement gneiss of the Shillong plateau and the overlying rocks of the Shillong basin have been dissected by a number of mafic dyke swarms represented by older Proterozoic dolerite dykes and sills named as Khasi greenstone and the younger set of Cretaceous dykes. The older dolerites dykes of Shillong basin are partly metamorphosed and have undergone low-grade metamorphism compared to the fresh unmetamorphosed Cretaceous dykes dominantly exposed in the BGC of West Garo hills region. The Khasi greenstones are tholeiitic in composition and range from basalt to basaltic andesite. Most of the metamorphosed mafic dykes indicate continental nature with some amount of overlapping oceanic tectonic setting. Palaeomagnetic study of the metadolerite dykes show a direction of magnetization of Dm=29, Im=38 (α₉₅ = 28.84; k = 48.33; N = 2) with a palaeolatitude of 21.3° N to the Indian sub-continent that clearly support the Proterozoic dyke/dyke swarm emplacement in the region. The magnetic carrier as inferred from IRM studies is magnetite in the range of psuedosingle to multi domain (MD) states with minor contribution from hematite.  相似文献   

Seismic velocity imaging of the Kumaon–Garhwal Himalaya,India     

Mandal  Prantik  Srinagesh  D.  Vijayaraghavan  R.  Suresh  G.  Naresh  B.  Raju  P. Solomon  Devi  Aarti  Swathi  K.  Singh  Dhiraj K.  Srinivas  D.  Saha  Satish  Shekar  M.  Sarma  A. N. S.  Murthy  YVVBSN 《Natural Hazards》2022,111(3):2241-2260

Natural Hazards - Since the initial collision at 55&nbsp;Ma, rocks of the Indian crust below the Himalayas have undergone modification chemically and compositionally due to the ongoing...  相似文献   

Axially-symmetric viscous fluid interacting with the gravitational field     

R. K. Tarachand Singh  A. Ratnaprabha Devi 《Astrophysics and Space Science》1989,158(2):259-264

The problem of an axially-symmetric viscous fluid interacting with the gravitational field has been investigated. Exact solutions have been obtained for the pressure and density of the viscous fluid. Physical interpretation of the solutions in respect of the expansion factor, acceleration components reality conditions of the distribution, etc., have been made.  相似文献   

Aerosols and their influence on radiation partitioning and savanna productivity in northern Australia     

Kasturi Devi Kanniah  Jason Beringer  Nigel J. Tapper  Chuck N. Long 《Theoretical and Applied Climatology》2010,100(3-4):423-438

Aerosols have been shown to affect the quantity and quality of solar radiation on the Earth’s surface. Savanna regions are subject to frequent burning and release of aerosols that may impact on radiation components and possibly vegetation productivity in this region. Therefore, in this study, we have analyzed the optical properties of aerosols (aerosol optical depth (AOD) and Angstrom coefficient) from the Atmospheric Radiation Measurement site in Darwin for the periods from April 2002 to June 2005 as measured by a multifilter rotating shadowband radiometer. The influence of aerosols and their effect on surface shortwave incoming solar radiation and savanna productivity were examined for the dry season using sky radiation collection of radiometers and eddy covariance measurements from the Howard Springs flux site. Results indicated that aerosol concentrations in the region were relatively low compared to other savanna regions with the maximum monthly average AOD over the period being the greatest in October (0.29?±?0.003 standard error at 500 nm). The highest monthly average Angstrom exponent was also found in October (1.38?±?0.008). The relatively low aerosol concentration in this region can be attributed to the mixture of smoke aerosols with humidity haze and local circulations. Over a range of AODs from 0.1 to 0.4, we found a modest increase in the fraction of diffuse radiation to total radiation from 11% to 21%. This small increase in diffuse fraction did not affect the carbon flux significantly. However, because the current range of AOD in the region is relatively low, the region could be sensitive to increases in aerosols and diffuse fraction in the future.  相似文献   

Cosmological models with generalised gravitational and cosmological constants     

N. Ibotombi Singh  S. Surendra Singh  S. Romaleima Devi  A. Sumati Devi 《Astrophysics and Space Science》2009,324(1):67-70

We consider cosmology with the gravitational and cosmological constants generalized as coupling scalars in Einstein’s theory. A general method of solving the field equations is given. We study here the exact solutions for negative pressure models satisfying G=G ₀(R/R ₀) ⁿ .  相似文献