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141.
142.
P. V. Nagamani M. I. Hussain S. B. Choudhury C. R. Panda P. Sanghamitra R. N. Kar A. Das I. V. Ramana K. H. Rao 《Journal of the Indian Society of Remote Sensing》2013,41(1):117-125
In this paper we report chlorophyll measurements made during an ocean colour validation cruise in April 2011 of the research vessel, Sagar Paschimi in the coastal waters of Northern Bay of Bengal. The chlorophyll-a concentration in these waters range from 0.2 to 4.0 mg/m3. Chlorophyll-a concentration from OCM-2 was estimated using the global ocean colour algorithms namely, OC2, OC3, OC4 and Chl-a algorithms respectively. OCM data was processed using the global SeaWiFS Data Analysis System (SeaDAS) in which all the above mentioned algorithms are embedded for estimating the chlorophyll-a concentration. A comparative study was made between and in-situ and satellite derived chlorophyll-a concentration. Although the matchups between in-situ and satellite data from OCM-2 were sparse, it indicates that direct application of the standard SeaWiFS algorithm-the OC4-V4 algorithm—in the coastal waters of the Bay of Bengal will underestimate chlorophyll-a by up to 30%. The results show a good correlation with an R value of 0.61 using OC2 algorithm. However, all the other global algorithms over estimate the chlorophyll-a concentration even in low chlorophyll concentration range. The comparison between in-situ and all the existing chlorophyll algorithms shows the efficiency of these algorithms for quantification of chlorophyll in coastal waters and hence the need to develop regional algorithms and fluorescence based algorithms for better quantification. 相似文献
143.
D. Poornima R. Shanthi S. Raja G. Vijayabaskara Sethubathi T. Thangaradjou T. Balasubramanian K. N. Babu A. K. Shukla 《Journal of the Indian Society of Remote Sensing》2013,41(3):651-662
Spatial and temporal distribution of chlorophyll a (chl a) and Total Suspended Matter (TSM) and inter comparison of Ocean Color Monitor-2 (OCM-2) and Moderate Resolution Imaging Spectro-radiometer (MODIS-Aqua) derived chlorophyll a and TSM was made along the southwest Bay of Bengal (BoB). The in-situ chl a and TSM concentration measured during different seasons were ranged from 0.09 to 10.63 μgl?1 and 11.04–43.75 mgl?1 respectively. OCM-2 and MODIS derived chl a showed the maximum (6–8 μgl?1) at nearshore waters and the minimum (0–1 μgl?1) along the offshore waters. OCM-2 derived TSM imageries showed the maximum (50–60 mgl?1) along the nearshore waters of Palk Strait and the moderate concentration (2–5 mgl?1) was observed in the offshore waters. MODIS derived minimum TSM concentration (13.244 mgl?1) was recorded along the offshore waters, while the maximum concentration of 15.78 mgl?1 was found along the Kodiakarai region. The inter-comparison of OCM-2 and MODIS chl a data (R 2 ?=?0.549, n?=?49, p?<?0.001, SEE?=?±0.117) indicate that MODIS data overestimates chl a concentration in the nearshore waters of the southern BoB compared to the OCM-2. The correlation between OCM-2 and MODIS-Aqua TSM data (R 2 ?=?0.508, N?=?53, P?<?0.001 and SEE?=?±0.024) confirms that variation in the range of values measured by OCM-2 (2–60 mgl?1) and the MODIS (13–16 mgl?1) derived TSM values. Despite problems in range of measurements, persistent cloud cover etc., the launch of satellites like OCM-2 with relatively high spatial resolutions makes job easier and possible to monitor chl a distribution and sediment discharges on day to day basis in the southwest BoB. 相似文献
144.
Standard least-squares collocation (LSC) assumes 2D stationarity and 3D isotropy, and relies on a covariance function to account
for spatial dependence in the observed data. However, the assumption that the spatial dependence is constant throughout the
region of interest may sometimes be violated. Assuming a stationary covariance structure can result in over-smoothing of,
e.g., the gravity field in mountains and under-smoothing in great plains. We introduce the kernel convolution method from
spatial statistics for non-stationary covariance structures, and demonstrate its advantage for dealing with non-stationarity
in geodetic data. We then compared stationary and non- stationary covariance functions in 2D LSC to the empirical example
of gravity anomaly interpolation near the Darling Fault, Western Australia, where the field is anisotropic and non-stationary.
The results with non-stationary covariance functions are better than standard LSC in terms of formal errors and cross-validation
against data not used in the interpolation, demonstrating that the use of non-stationary covariance functions can improve
upon standard (stationary) LSC. 相似文献
145.
S. Patro C. Chatterjee S. Mohanty R. Singh N. S. Raghuwanshi 《Journal of the Indian Society of Remote Sensing》2009,37(1):107-118
A coupled 1D-2D hydrodynamic model, MIKE FLOOD was used to simulate the flood inundation extent and flooding depth in the
delta region of Mahanadi River basin in India. Initially, the 1D model MIKE 11 was calibrated using river water level and
discharge data of various gauging sites for the monsoon period (June to October) of the year 2002. Subsequently, the calibrated
set up was validated using both discharge and water level data for the same period of the year 2001. The performance of calibration
and validation results of MIKE 11 were evaluated using different performance indices. A bathymetry of the study area with
a spatial resolution of 90m was prepared from SRTM DEM and provided as an input to the 2D model, MIKE 21. MIKE 11 and MIKE
21 models were then coupled using lateral links to form the MIKE FLOOD model set up for simulating the two dimensional flood
inundations in the study area. Flood inundation is simulated for the year 2001 and the maximum flood inundation extent simulated
by the model was compared with the corresponding actual inundated area obtained from IRS-1D WiFS image. 相似文献
146.
K. N. Prudhvi Raju Sarvajeet Kumar Kshitij Mohan Manish Kumar Pandey 《Journal of the Indian Society of Remote Sensing》2008,36(3):283-288
With growing urban expanses, one of the pre-requisites for effective governance is Urban Information Systems (UIS) with content
down to individual properties (and individuals). The basic input i.e., a map, in UIS should show individual property boundaries
showing the plan outline of all structures existing within, at a scale of 1:1000 and larger with sub-metre to centimeters
planimetric and geometric accuracy. With very high resolution remote sensing data of the order of 1m available in hand, it
is possible to prepare maps with high resolution spatial content. The present exercise demonstrates a method of preparing
a geometrically and planimetrically accurate urban cadastral map on very large scale for a small area of about 5 sq km. IKONOS
merged data with 1m resolution is used for the purpose. Mapping was done in conjunction with on-site measurements and sketches.
Guides are used to maintain shape symmetry and accuracy of buildings and other features. Working out cost of mapping per unit
area is another objective in the present exercise. For want of fully or semi-automatic methods of information extraction from
very high resolution remote sensing data, it is imperative that mapping should be carried out in conjunction with some on-site
measurements wherever necessary. 相似文献
147.
148.
A. K. Singh P. K. Singh B. Lal A. N. Singh A. Mathur 《Journal of the Indian Society of Remote Sensing》2008,36(2):183-188
A World Bank-aided project on sodic land reclamation in Uttar Pradesh is being executed by U.P. Bhumi Sudhar Nigam, Lucknow,
and Remote Sensing Applications Centre, U.P., Lucknow has the responsibility of sodic land mapping for the execution of land
reclamation programme at the cadastral level. Sodic lands are mainly concentrated in the Gangetic alluvial plains but the
problem of sodicity is particularly acute in the canal-irrigated areas. A study of the distribution pattern of sodic lands
in canal and noncanal command areas in a reclamation site (covering 60 villages out of which sodic lands were mapped in 51
villages) of Etah district in Uttar Pradesh, indicates that 18.39 per cent area of the canal command villages was barren sodic
which was 13.41 per cent of the total geographical area of the site (15417 ha), however, 11.69 per cent area was recorded
to be barren sodic in the non-canal command villages which was only 3.16 per cent of the geographical area of the site. The
results of soil chemical analysis indicate that barren sodic lands of canal command area are saline-sodic with higher concentration
of soluble salts (pH2 >8.5, EC2 >4 dSm−1), however, those of non-canal command area are sodic (pH2 >8.5, EC2 <4 dSm−1). The post-monsoon ground level in the canal-irrigated areas was in the critical and semicritical zone (< 3.0 mbgl) whereas
it was well below the semi-critical zone in the non-canal command area, which indicates that the high ground water level is
a major factor to higher the area under sodicity. 相似文献
149.
S. Anbazhagan N. K. Sainaba S. Arivazhagan 《Journal of the Indian Society of Remote Sensing》2012,40(1):145-153
In the present study, The Landsat 7 ETM satellite data was collected for the Sittampundi anorthosites complex and digital
image analysis was carried out. The anorthositic rocks available at Sittampundi complex is considered as an equivalent of
lunar highland rocks. Hence, a remote sensing study comprises of image analysis and spectral profile analysis was carried
out. The satellite data was digitally processed and generated various outputs like band combinations, color composites, stretched
outputs, and PCA. The suitable processed outputs were identified for delineating the anorthosite complex. The diagnostic absorption
features of reflectance spectra are the sensitive indicators of mineralogy and chemical composition of rocks, which are interest
to the planetary scientists. The spectral profile of Landsat ETM plotted for pure and mixed anorthosite pixels and compared
with the field and lab reflectance spectra. The percentages of image spectra vary from 30% to 60% for Sittampundi anorthosite.
The spectral bands 2, 4 and 6 have low reflectance and bands 3 and 5 have high reflectance. The spectral range of bands 2,3,4,5
and 6 are 525 nm–605 nm, 630 nm–690 nm, 750 nm–900 nm, 1550 nm–1750 nm and 10400 nm–12500 nm respectively. The field spectral
curve has weak absorptions at 650 nm and 1000 nm due to the iron transition absorption and low ca- pyroxene respectively available
in the anorthosite, matching with the image spectra. However, hyperspectal image with narrow bandwidth could be more useful
in selecting the suitable spectrum for remotely mapping the anorthosite region, as equivalent test site for lunar highland
region. 相似文献
150.
Dhruvesh P Patel Mrugen B Dholakia N. Naresh Prashant K. Srivastava 《Journal of the Indian Society of Remote Sensing》2012,40(2):299-312
Geo-visualization concept has been used for positioning water harvesting structures in Varekhadi watershed consisting of 26
mini watersheds, falling in Lower Tapi Basin (LTB), Surat district, Gujarat state. For prioritization of the mini watersheds,
morphometric analysis was utilized by using the linear parameters such as bifurcation ratio (Rb), drainage density (Dd), stream frequency (Fu), texture ratio (T), length of overland flow (Lo) and the shape parameter such as form factor (Rf), shape factor (Bs), elongation ratio (Re), compactness constant (Cc) and circularity ratio (Rc). The different prioritization ranks were assigned after evaluation of the compound factor. 3 Dimensional (3D) Elevation
Model (DEM) from Shuttle Radar Topography Mission (SRTM) and DEM from topo contour were analyzed in ArcScene 9.1 and the fly
tool was utilized for the Geo-visualization of Varekhadi mini watersheds as per the priority ranks. Combining this with soil
map and slope map, the best feasibility of positioning check dams in mini-watershed no. 1, 5 and 24 has been proposed, after
validation of the sites. 相似文献