Influence of Atmospheric Water Vapour on IRS NIR Measurements for Detecting Vegetation Signal. Part II: Validation of Simulation Results using Hyperion Data     

Mehul R. Pandya  Raghavendra Pratap Singh  Sushma Panigrahy  Jai Singh Parihar 《Journal of the Indian Society of Remote Sensing》2012,40(2):225-229

This is the second paper of the series on the influence of the atmospheric water vapour (WV) on IRS NIR measurements. In the first paper (Pandya et al. 2011) a simulation study was presented where through the radiative transfer calculations it was shown that the variation of 0 to 6 g/cm² in the WV hampered the IRS NIR reflectance up to 14%. In that study splitting of IRS NIR (0.770–0.860 μm) into two bands, such as NIR1 (0.775–0.805 μm) and NIR2 (0.845–0.875 μm) was also proposed, which facilitated a considerable improvement in NIR reflectance as well as in NDVI. Objective of the present paper is to validate the findings of simulation study with the use of EO1-Hyperion data. An improvement of the order of 7% in the top-of-atmosphere reflectance over vegetation target was obtained from the satellite data analysis, which is in good agreement to that of simulation results (3.7 to 7.9%) for the continental WV conditions of 1 to 3 g/cm². This is also true for NDVI values, which illustrated a good agreement between the satellite observations (2.5%) and simulation results (2 to 4.6%) for the magnitude of improvement. Findings of the present study are preliminary in the nature but it provides a basis for enhanced NIR observations for future IRS sensors.  相似文献   

Resource constraint mapping and management in arid tract of Punjab     

V. K. Verma  Anil Sood  P. K. Sharma  Charanjit Singh  M. L. Manchanda 《Journal of the Indian Society of Remote Sensing》1996,24(1):11-23

The arid tract of Punjab experiences various problems like thick sand cover (sand dunes) in large area, poor retention of water and nutrients in coarse textured soils, soil salinity and/or alkalinity, water logging and poor ground water quality. In the present study multidate remotely sensed data both in the form of aerial photographs and satellite imagery on 1:50,000 scale were interpreted visually to map physiography and soils. The ground water samples from tubewells distributed all over the area were collected and analysed to prepare ground water quality map. The soil and ground water quality maps were integrated to produce a resource constraint map of the area showing physical, chemical and hydrological constraints. The study revealed that alluvial plain suffers from hydrological constraints due to marginal to.poor ground water in 86% of the total area. The sand dunes show both physical and hydrological constraints due to coarse textured (sandy) soils and brackish ground water. The basins having soil salinity and brackish ground water cover 0.10% of the area. Keeping in view the type of constraint, locale specific measures like levelling and stabilisation of sand dunes, reclamation of salt affected and water logged areas followed by plantation of tree species which act as biopumps are suggested. The conjuctive use of surface (canal) and ground water is essential to prevent secondary salinization and sodification. The study demonstrates the potential usefulness of remote sensing technology in mapping natural resources and assess the nature, magnitude and spatial distribution of resource constraints.  相似文献   

Soil—landscape relationship of Hissar District using aerial photo — interpretation technique     

R. L. Ahuja  V. N. Garalapuri  M. L. Manchanda  B. K. Suneja  B. S. Sangwan 《Journal of the Indian Society of Remote Sensing》1979,7(2):39-44

Soil survey of Hissar district (Haryana) covering total area of 6,331 sq. kms. was carried out using the aerial photographs of 1 : 25,000 scale. A detailed physiographic legend was prepared and boundaries were confirmed in relation to soil. Soil-landscape relationship was established during the course of study. Four major physiographic units were identified in the area : i. e. i) Aeolian plain, ii) Alluvial plain, iii) Drishdawati flood plain, iv) Ghaggar flood plain. Each of the major unit was sub-divided on the basis of photo elements, tone, texture, erosion, parcelling etc. The soils of the sand dunes/ Bars are classified as Typic Torripsamments/Ustipsamments; plain-Typic, Camborthids/Calciorthids/Ustrochrepts; basins-Aquic Ustochrepts and salt affected plain-Aquic Natrustalfs.  相似文献   

Crop classification accuracy as influenced by training strategy,data transformation and spatial resolution of data     

T T Medhavy  Tara Sharma  R P Dubey  R S Hooda  K E Mothikumar  M Yadav  M L Manchanda  D S Ruhal  A P Khera  S D Jarwal 《Journal of the Indian Society of Remote Sensing》1993,21(1):21-28

The possibility of improving classification accuracies using different training strategies and data transformations within the framework of a supervised maximum likelihood classification scheme was explored in this study. The effect of spatial resolution of data on the accuracy of classification was also studied Single-pixel training strategy resulted in improved classification accuracy over the block-training method. Data transformations gave no significant improvements in accuracy over untransformed data. There was a reduction in classification accuracy as resolution of data improved from 72 m (LISS I) to 36 m (LISS II) while other sensor characteristics remained same.  相似文献   

Discrimination of newly planted and ratoon crops of sugar cane using multidate IRS-1C liss III data: A knowledge based approach     

M Kudrat  K P Sharma  A K Tiwari  Pramod Kumar  B Prabhakaran  M L Manchanda 《Journal of the Indian Society of Remote Sensing》2000,28(2-3):179-185

An advanced and accurate information of sugar cane production is an important component for the management of sugar cane industry. Remote Sensing is most viable technique which can provide the above information well in advance. Stratified sampling technique practiced in Crop Acreage and Production Estimation (CAPE) programme holds good for major crops with non-overlapping growth stages. Discrimination of ratoon and newly planted sugar cane crop is a challenging task. Single date remote sensing data does not suffice to discriminate the above two types of sugar cane. In the present paper, an attempt has been made to show how two date remote sensing data coupled with knowledge based approach dramatically improves the classification accuracy (98%) of sugar cane crop as compared to the stratified sampling approach (less than 90%). This has been demonstrated in a case study comprising parts of two districts of western Uttar Pradesh.  相似文献   

Large Area X-Ray Proportional Counter (LAXPC) Instrument on AstroSat and Some Preliminary Results from its Performance in the Orbit     

P. C. Agrawal  J. S. Yadav  H. M. Antia  Dhiraj Dedhia  P. Shah  Jai Verdhan Chauhan  R. K. Manchanda  V. R. Chitnis  V. M. Gujar  Tilak Katoch  V. N. Kurhade  P. Madhwani  T. K. Manojkumar  V. A. Nikam  A. S. Pandya  J. V. Parmar  D. M. Pawar  Jayashree Roy  B. Paul  Mayukh Pahari  Ranjeev Misra  M. H. Ravichandran  K. Anilkumar  C. C. Joseph  K. H. Navalgund  R. Pandiyan  K. S. Sarma  K. Subbarao 《Journal of Astrophysics and Astronomy》2017,38(2):30

Large area X-ray propositional counter (LAXPC) instrument on AstroSat is aimed at providing high time resolution X-ray observations in 3–80 keV energy band with moderate energy resolution. To achieve large collecting area, a cluster of three co-aligned identical LAXPC detectors, is used to realize an effective area in access of \({\sim }6000\,\hbox {cm}^{2}\) at 15 keV. The large detection volume of the LAXPC detectors, filled with xenon gas at \({\sim }\)2 atmosphere pressure, results in detection efficiency greater than 50%, above 30 keV. In this article, we present salient features of the LAXPC detectors, their testing and characterization in the laboratory prior to launch and calibration in the orbit. Some preliminary results on timing and spectral characteristics of a few X-ray binaries and other type of sources, are briefly discussed to demonstrate that the LAXPC instrument is performing as planned in the orbit.  相似文献   

Characterisation of Residue Burning from Agricultural System in India using Space Based Observations     

Chandra Prakash Singh  Sushma Panigrahy 《Journal of the Indian Society of Remote Sensing》2011,39(3):423-429

Biomass burning is a global phenomenon with agriculture residue burning having a sizeable share. Biomass burning is a major source of emission of green house gases (GHGs). Thus the space-based observations of global distribution of fire form a key component of climate change studies. This study is a step towards understanding the spatio-temporal occurrence of agricultural residues burning in Indo-Gangetic plains of India using fire products from space borne satellites. The 3 years daily active fire data of MODIS (Aqua/Terra) from August, 2006 to July, 2009 have been used in this study. The data analysis showed that out of total fire events, around 69% contribution comes from agricultural areas and remaining (31%) comes from non-agricultural areas. This is mainly due to the intensive cultivation in this belt. The characterisation analysis revealed that, 84% of agriculture residues burning is from Rice-Wheat system (RWS) alone and remaining 16% in other types of crop rotations. The fire incidents were very high in October–December (55%) compared to that in March–May (36%), further indicating that burning of rice residue is more prevalent than that of wheat.  相似文献   

A study of the H-alpha line in late G and K supergiants     

Sushma Vasu Mallik 《Journal of Astrophysics and Astronomy》1982,3(1):39-61

A spectroscopic study of H_α has been carried out to investigate the properties of expanding chromospheres of late G and K supergiants. Spectra of 23 stars brighter thanV = 6.0 have been obtained at dispersions of 4–10 å mm^-1 using the coude and the coudé-echelle spectrographs at the 102-cm telescope of Kavalur Observatory. The H_α profiles are all asymmetric in the sense that the absorption core is shifted to the blue by amounts ranging between -4 and -24 km s^-1. H_α profiles were theoretically computed using radiative transfer in spherically symmetric expanding atmospheres covering a large range of integrated optical depths. These were compared with the characteristics of the observed line in the programme stars. The analysis shows that the H_α line is formed in a region with velocity increasing outward. The computed equivalent widths and line core displacements were matched with those observed to obtain hydrogen column densities and expansion velocities. From these, the rates of mass loss in these stars were determined to be in the range of 10⁶10^-7 M_⊙ yr^-1.  相似文献   

Developing Spectral Library of Major Plant Species of Western Himalayas Using Ground Observations     

K. R. Manjunath  Amit Kumar  Mehra Meenakshi  R. Renu  S. K. Uniyal  R. D. Singh  P. S. Ahuja  S. S. Ray  Sushma Panigrahy 《Journal of the Indian Society of Remote Sensing》2014,42(1):201-216

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Assessment of Late Blight Induced Diseased Potato Crops: A Case Study for West Bengal District Using Temporal AWiFS and MODIS Data     

Sujay Dutta  Suresh K. Singh  Sushma Panigrahy 《Journal of the Indian Society of Remote Sensing》2014,42(2):353-361

Remote sensing technology becomes an effective and inexpensive technique for detecting disease in vegetation. In this study, an attempt has been done to discriminate healthy and late blight affected crop using remote sensing based indices such as NDVI and LSWI. NDVI and LSWI spectral profiles between healthy and late blight affected crop shows large difference. Mean difference in reflectance between two acquired dates Jan. 10 and 29, 2009 crop clusters varied from 31.28 % in red band, 7.7 % in NIR band and 6.23 % in SWIR bands in healthy crops while in late blight affected crops it is ?15.5 % in red, 44.4 % in NIR and ?14.61 % in SWIR bands. Negative percentage differences in reflectance indicate reflectance increases from Jan. 10, 2009 to Jan. 29, 2009, while positive difference indicate decrease in reflectance between the two dates. Since potato is an irrigated crop, these differences in reflectance are attributed to prevalent disease at that time. It is found that severely affected areas are Bardhman, Arambag, Bishnupur, Ghatal and Hugli taluka with crop damage areas are 4036.66, 1138.68, 2025.23, 469.15, and 380.08 ha, respectively.  相似文献