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21.
K. V. S. Badarinath K. Madhavilatha T. R. Kiran Chand M. S. R. Murthy 《Journal of the Indian Society of Remote Sensing》2004,32(4):343-350
Generation of fire danger maps play a vital role in forest fire management like forest fire research, locating lookout towers,
risk assessment and for various other simulation studies. The present study addresses remote sensing and GIS applications
in generating fire danger maps for tropical deciduous forests. Fire danger variables such as fuel type, topography, temperature,
and relative humidity have been used in modeling fire danger. Information on local climate patterns and past fire records
has been used to derive fire frequency map of the study area. Intermediate indices were derived using multiple regressions,
where fire frequency data is taken as dependent variable. Results indicate that forests near human settlements are more vulnerable
to forest fires. 相似文献
22.
D. Vamsi Kiran C. Srinivasa Rao R. Ramakrishnan P. Gupta 《Journal of the Indian Society of Remote Sensing》2004,32(3):269-286
This paper discusses algorithms for compressing floating point data which is encountered while performing resampling algorithm
for rectifying geometric distortions on the images transmitted by the remote sensing satellite on a distributed computing
environment. Two efficient algorithms for encoding and decoding floating point data compression, (i) 3-byte packing and (ii)
3-byte + 2-bit packing have been proposed. Both algorithms are tested to execute resampling algorithm on radiometrically corrected
for IRS- LISS-III 4 bands data on a distributed system. First algorithm compresses 4-byte floating point data to 3-byte obtaining
25% compression while later one compresses 4-byte floating point data to 3-byte + 2-bit achieving about 18.75% compression.
The computational time is reduced by 22% as compared to the distributed resampling algorithms without compression. Further
it is found that in lossy compression algorithm only 220 pixels out of 37.4 MB pixels have utmost one Gray count difference,
which will not pose any issues for digital classification or any other methods that will be employed in the corrected image
by Image Analysts. 相似文献
23.
UNCERTAINTY IN THE SPECIFICATION OF SURFACE CHARACTERISTICS: A STUDY OF PREDICTION ERRORS IN THE BOUNDARY LAYER 总被引:1,自引:0,他引:1
The effects of uncertainty in the specification of surface characteristics on simulated atmospheric boundary layer (ABL) processes and structure were investigated using a one-dimensional soil-vegetation-boundary layer model. Observational data from the First International Satellite Land Surface Climatology Project Field Experiment were selected to quantify prediction errors in simulated boundary-layer parameters. Several numerical 12-hour simulations were performed to simulate the convective boundary-layer structure, starting at 0700 LT 6 June 1987.In the control simulation, measured surface parameters and atmospheric data were used to simulate observed boundary-layer processes. In the remaining simulations, five surface parameters – soil texture, initial soil moisture, minimum stomatal resistance, leaf area index, and vegetation cover – were varied systematically to study how uncertainty in the specification of these surface parameters affects simulated boundary-layer processes.The simulated uncertainty in the specification of these five surface parameters resulted in a wide range of errors in the prediction of turbulent fluxes, mean thermodynamic structure, and the depth of the ABL. Under certain conditions uncertainty in the specifications of soil texture and minimum stomatal resistance had the greatest influence on the boundary-layer structure. A lesser but still moderately strong effect on the simulated ABL resulted from (1) a small decrease (4%) in the observed initial soil moisture (although a large increase [40%] had only a marginal effect), and (2) a large reduction (66%) in the observed vegetation cover. High uncertainty in the specification of leaf area index had only a marginal impact on the simulated ABL. It was also found that the variations in these five surface parameters had a negligible effect on the simulated horizontal wind fields. On the other hand, these variations had a significant effect on the vertical distribution of turbulent heat fluxes, and on the predicted maximum boundary-layer depth, which varied from about 1400–2300 m across the 11 simulations. Thus, uncertainties in the specification of surface parameters can significantly affect the simulated boundary-layer structure in terms of meteorological and air quality model predictions. 相似文献
24.
25.
C.?T.?Sabeerali Suryachandra?A.?RaoEmail author A.?R.?Dhakate K.?Salunke B.?N.?Goswami 《Climate Dynamics》2015,45(1-2):161-174
Future projections of the Indian summer monsoon rainfall (ISMR) and its large-scale thermodynamic driver are studied by using CMIP5 model outputs. While all models project an increasing precipitation in the future warming scenario, most of them project a weakening large-scale thermodynamic driver arising from a weakening of the upper tropospheric temperature (UTT) gradient over south Asian summer monsoon region. The weakening of the UTT gradient under global warming scenarios is related to the increase in sea surface temperature (SST) over the equatorial Indian Ocean (EIO) leading to a stronger increase of UTT over the EIO region relative to the northern Indian region, a hypothesis supported by a series of Atmospheric General Circulation Model (AGCM) experiments forced by projected SSTs. To diagnose the inconsistency between the model projections of precipitation and the large-scale thermodynamic driver, we have examined the rate of total precipitation explained by convective and stratiform precipitations in observations and in CMIP5 models. It is found that most models produce too much (little) convective (stratiform) precipitation compared to observations. In addition, we also find stronger precipitable water—precipitation relationship in most CMIP5 models as compared to observations. Hence, the atmospheric moisture content produced by the model immediately gets converted to precipitation even though the large-scale thermodynamics in models weaken. Therefore, under global warming scenarios, due to increased temperature and resultant increased atmospheric moisture supply, these models tend to produce unrealistic local convective precipitation often not in tune with other large-scale variables. Our results questions the reliability of the ISMR projections in CMIP5 models and highlight the need to improve the convective parameterization schemes in coupled models for the reliable projections of the ISMR. 相似文献
26.
Proper selection and ranking of Ground Motion Prediction Equations (GMPEs) is critical for successful logic-tree implementation
in probabilistic seismic hazard analysis. The present study explores this issue in predicting peak ground accelerations at
the rock sites in India. Macroseismic intensity data complemented with limited strong ground-motion recordings are used for
the purpose. The findings corroborate the possible conformity between the GMPEs developed for tectonically active shallow
crust across the globe. On the other hand, the relevant GMPEs in the intraplate regions cluster into two different groups
with the equations of lower ranks catering to higher ground motions. The earthquakes in the subduction zones have significant
regional implications. However, affinity in the ground-motion attenuations between the major interface events (M
W > 7.4) in Andaman-Nicobar, Japan and Cascadia, respectively, is noted. This can be also observed for the intraslab events
in the Hindukush and Taiwan respectively. Overall, we do not observe any significant advantage with the equations developed
using the regional data. These findings are expected to be useful in probabilistic seismic hazard analysis across the study
region. 相似文献
27.
The temporal variation in intermediate-degree-mode frequencies is analysed using helioseismic data which cover the minimum to the maximum phase of the current solar cycle. To study the variation in detail, the measured frequency shifts of f and p modes are decomposed into two components, viz., oscillatory and non-oscillatory. The f-mode frequencies exhibit prominent oscillatory behavior in contrast to p modes where the oscillatory nature of the frequencies is not clearly seen. Also, the oscillatory part contributes significantly to the f-mode frequencies while p-mode frequencies have maximum contribution from the non-oscillatory part. The amplitude of both oscillatory and non-oscillatory parts is found to be a function of frequency. The non-oscillatory part is observed to have a strong correlation with solar activity. 相似文献
28.
We made polarimetric observations of comet Hale–Bopp covering awide phase angle range, from 18.8 to 47°. At certain phase angles the heliocentricdistance of the comet was less than 1 AU during its pre and post perihelion passages. Oneof the important findings, based on the data in the visual bands, is the higher polarizationwith stronger wavelength dependence compared to comet Halley, indicating the presenceof much finer grains in comet Hale–Bopp. It may also be noted that comet Hale–Bopphas shown highest degree of polarization known so far for any comet and hence fallsin the class of high polarization comets. Polarimetric observations were made of cometC/2000 WM1 (LINEAR)using narrow band (IHW) filters 4845 Å and 7000 Åand broad bands filters BVR during November 23–26, 2001 when the phase angle rangedfrom 15 to 22°. Some of the results based on these observations are presented anddiscussed. 相似文献
29.
Ocean Dynamics - In this study, the behaviour of cyclones in the Bay of Bengal in future climatic conditions is analysed with the help of an ocean-atmosphere coupled model. The weather research and... 相似文献
30.
Kiran Lakhchaura K. P. Singh D. J. Saikia R. W. Hunstead 《Journal of Astrophysics and Astronomy》2011,32(4):493-494
Using X-ray observations from Chandra and XMM-Newton and radio observations from the Australia Telescope Compact Array (ATCA),
we have examined the merging environment of the bimodal cluster Abell 3395. From X-ray data we have produced thermodynamic
maps of the cluster. The Wide Angle Tail (WAT) galaxy seen in the radio is slightly offset from the X-ray emission peak of
the southern part of the cluster. The unsharp masked Chandra image of the cluster does not show any deficit in the X-ray flux
near the location of the source possibly because the thermal plasma has leaked into the cavities. 相似文献