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41.
N. M. Gavrilov 《Izvestiya Atmospheric and Oceanic Physics》2007,43(4):451-460
Data of an experiment on radio occultation sounding of the atmosphere with the use of GPS signals were used to obtain global distributions of the variances of mesoscale variations in the refractive index in the troposphere and stratosphere. The experiment was carried out with the CHAMP satellite during the period 2001–2005. Measured vertical profiles were smoothed inside 5–10-km-thick layers centered at different altitudes in the troposphere and stratosphere with the use of second-degree polynomials. Deviations from the smoothed quantities and the corresponding variances were obtained for each profile and averaged for each month during the analyzed interval of the CHAMP experiment. Altitude-longitude-latitude inhomogeneities in the distribution of refractive index variances were analyzed. Altitude and latitude distributions of maxima and minima of refractive index variances depend on altitude and season. Turbulence and acoustic gravity waves can be the causes of small-scale and mesoscale variations in the refractive index of the troposphere and stratosphere. The variances of variations in the refractive index are greater in the regions of tropospheric jet streams and in the zones of near-equatorial deep convection. Atmospheric disturbances increase over mountain systems. 相似文献
42.
The nonlinear energy transfer through the wave spectrum is studied on the basis of the previously obtained explicit equation for matrix elements of a four-wave kinetic integral. The equation describes the evolution of a system of gravity waves at the surface of a sea of finite depth with a uniform distribution of broken ice over the sea surface. Particular attention is paid to the analytical part of the algorithm of the calculation of the kinetic integral. This part differs from the standard algorithm by a set of prominent features of the dispersion relation for wave oscillations in the ice-covered water. The kinetic integral for the system under consideration is calculated, and the results are compared with the results obtained for the ice-free water. 相似文献
43.
This paper studies two properties of chromospheric spicules: their angular distribution and the plasma velocity along their axes. To investigate the first property, we measured the apparent tilt of spicules at the limb, and then computed their actual distribution in space. This was achieved by solving first kind Fredholm or Volterra integral equations by various methods. The distribution of the axial velocity of the spicule plasma was studied on the basis of two types of observations: (1) the height variation of the spicules as a function of time and (2) the Doppler shift of the spectral lines. The resulting velocity distributions, using the experimental data of these two sets of observations, are quite different. The average velocity based on the Doppler shift measurements ( 40 km s–1) is greater than that based on height variation of spicules ( 20 km s–1). This is due to the ionization of the material as it penetrates the corona. 相似文献
44.
V. Nagasubramanian P. V. Radhadevi R. Ramachandran R. Krishnan 《Journal of the Indian Society of Remote Sensing》2008,36(1):27-35
Rational Function Model (RFM) is the alternate sensor Model to the rigorous sensor model that allows end user to perform sensor-independent
photogrammetric processing. Nowadays, commercial off-the-shelf (COTS) digital photogrammetric work stations have incorporated
RFM as a method for image restitution. It is technically applicable to all types of airborne and space borne sensors. In this
paper, we describe the derivations of the algorithmic procedure for third order inverse and forward RFM method for 3-D reconstruction.
Model accuracy is evaluated for aerial image, TK-350 Russian image and IRS-1C PAN image. The results ensure that properly
constructed RFM are accurate enough to be used in place of the original rigorous models. The test results are reported and
summarised. 相似文献
45.
P. Jayaprasad B. Narender S. K. Pathan Ajai 《Journal of the Indian Society of Remote Sensing》2008,36(4):313-322
Digital elevation model (DEM) and the derived terrain parameters e.g. contour, slope, aspect, drainage pattern, etc are required
for natural resources management, infrastructure planning and disaster management. The present paper aims at generating DEM
from ERS tandem pair using interferometric technique supported by differential GPS measurements (DGPS) and multispectral optical
data. Validation of DEM has been carried out by DGPS measurements. Ground Control Points (GCP) established by DGPS measurements
have been used to georeference the IRS-1D optical data that has finally been co-registered with SAR amplitude image. Optical
data, co-registered with ERS - I SAR data has helped in locating the GCP’s and check points, precisely, for refinement of
DEM and its validation. 相似文献
46.
R. Raaj M. Ramalingam S. K. Ghosh U. C. Kothyari 《Journal of the Indian Society of Remote Sensing》2008,36(1):61-68
This article reports a preliminary work in which two site specific seasonal algorithms have been proposed for estimating the
suspended sediments concentration (SSC) from the digital numbers recorded on Indian Remote sensing Satellite, IRS-P4 Ocean
Colour Monitor (OCM) sensor. For estimation of SSC, the proposed algorithms utilize dark pixel deduction atmospheric correction
technique. The computations are performed with respect to north east monsoon phase situations of Palk Strait coastal stretch.
The algorithms performance was satisfactory during the north east monsoon period. Although the results obtained cannot be
generalized, we suggest that the authority of proposed algorithms can be extended to other seasons with the addition of more
temporal experimental validation data sets and with numeric constants adjusted to present existing conditions. (As this area
was severely affected by Tsunami, it may have dissimilar conditions at present). 相似文献
47.
K. S. Rao Y. S. Rao H. K. Al Jassar 《Journal of the Indian Society of Remote Sensing》2008,36(2):123-136
Spaceborne Imaging Radar (SIR-C) data acquired over Gujarat, India in 1994 were processed and analysed using differnet techniques
applicable to polarimetric SAR data such as polarization signatures, polarization index, decomposition of the signal and polarization
phase difference and limited groundtruth data. It has been observed that multi-frequency polarimetric data enhances the potential
of retrieving geo-physical parameters. The polarization signatures are found to vary with the nature of the target. Target
decomposition of the returned signal will be useful for the classification of various features. Polarization Phase Difference
(PPD) gives good information about the vegetation parameters. 相似文献
48.
49.
50.
This paper presents a continuous version of the model of distribution dynamics to analyse the transition dynamics and implied
long-run behaviour of the EU-27 NUTS-2 regions over the period 1995–2003. It departs from previous research in two respects:
first, by introducing kernel estimation and three-dimensional stacked conditional density plots as well as highest density regions
plots for the visualisation of the transition function, based on Hyndman et al. (J Comput Graph Stat 5(4):315–336, 1996), and second, by combining Getis’ spatial filtering view with kernel estimation to explicitly account for the spatial dimension of the
growth process. The results of the analysis indicate a very slow catching-up of the poorest regions with the richer ones,
a process of shifting away of a small group of very rich regions, and highlight the importance of geography in understanding
regional income distribution dynamics.
相似文献
Manfred M. FischerEmail: |