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481.
482.
The aim of this paper is to study the feasibility of deriving vertical wind profiles from current satellite observations.
With this aim, we carried out complex empirical orthogonal function (CEOF) analysis of a large number of radiosonde observations
of wind profiles over the Indian Ocean during the monsoon months. It has been found that the first two CEOFs explain 67% of
the total variance in wind fields. While the first principal component is well correlated with the winds at 850 mb (r = 0:80), the second one is highly correlated with winds at 200 mb (r = 0:89). This analysis formed the basis of a retrieval
algorithm which ensures the retrieval of vertical profiles of winds using satellite tracked cloud motion vector winds. Under
the assumption that accurate measurements of wind are available at the above mentioned levels, the r.m.s. error of retrieval
of each component of wind is estimated to range between 2 ms-1 and 6 ms-1 at different levels, which is much less than the natural variance of winds at these levels. For a better visualization of
retrieval, we have provided retrieved and true wind profiles side by side for four typical synoptic conditions during the
monsoon season. 相似文献
483.
We have simulated the return echo of a satellite altimeter from a rough ocean surface using an analytical formula and have
studied its sensitivity with respect to various oceanic and altimeter parameters. Our numerical experiment shows that for
normally observed significant wave heights (SWH) the effect of off-nadir angle (ONA) up to 0.5° on the leading edge is not
severe. Also, small surface roughness skewness seems to have little effect on the overall shape of the echo.
Newton’s iterative scheme has been used to retrieve SWH from the mean return waveform without noise and with additive Gaussian
noise typical of Seasat and Geosat altimeters. It has been observed that SWH can be retrieved in the presence of noise with
an accuracy of ±0.6 m for ONA less than 0.5°. For higher ONA, accurate retrieval requires the use of precomputed look-up table
along with our scheme. 相似文献
484.
Summary Based on field instrumentation in eight different coal mines representing varying depths and strata conditions, a relation for obtaining the critical convergence value has been established. In development heading for bord and pillar workings this relation can be used successfully to control the premature collapse of the roof. An empirical relation for rock load has been established. This can be utilized for optimum design of support system. The roofs have been categorized as stable, short-term stable and unstable. Proper attention should be provided for an unstable roof and the support design is to be changed before the convergence reaches the critical value. 相似文献
485.
The variational technique of data assimilation using adjoint equations has been illustrated using a nonlinear oceanographic
shallow water model. The technique consists of minimizing a cost function representing the misfit between the model and the
data subject to the model equations acting as constraints. The problem has been transformed into an unconstrained one by the
use of Lagrange multipliers. Particular emphasis has been laid on finite difference formulation of the algorithm. Several
numerical experiments have been conducted using simulated data obtained from a control run of the model. Implications of this
technique for assimilating asynoptic satellite altimeter data into ocean models have been discussed. 相似文献
486.
Anbazhagan P. Mog Kunjari Rao K. S. Nanjunda Prabhu N. Siddharth Agarwal Ayush Reddy G. R. Ghosh Sima Deb Malay Kr. Baruah Saurabh Das Sarat Kr. 《Natural Hazards》2019,98(2):425-450
Natural Hazards - An earthquake of moment magnitude Mw 5.7 shook the northeastern region of India on 3 January 2017 at 14 h:39 min:0.5 s local time. The duration of the... 相似文献
487.
Shibaji Banerjee Sanjay K. Ghosh Amal Mazumdar Sibaji Raha Debapriyo Syam 《Astrophysics and Space Science》2000,274(3):655-660
There have been several reports of exotic nuclear fragments, with highly unusual charge to mass ratio, in cosmic ray experiments.
Although there exist experimental uncertainties which make them, at best, only candidate `exotic' events, it is important
to understand what they could be, if they are eventually confirmed. Among other possible explanations, some authors have interpreted
them to be lumps of strange quark matter (strangelets).A major problem with such an interpretation is that to reach the earth's
surface, they must possess an unusually high penetrability through the terrestrial atmosphere. We show that a recently proposed
mechanism for the propagation of strangelets through the earth's atmosphere, together with a proper account of charge capture
and ionisation loss, would solve this problem. We also argue that this could lead to viable strategies for definitive detection
of strange quark matter in cosmic ray flux using aground based large area array of passive detectors.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
488.
Swagat Ghosh Thipramalai Thankappanpillai Ajith Kumar Thangavel Balasubramanian 《中国海洋大学学报(英文版)》2012,11(2):174-180
This study investigated the embryonic development of Maldives clownfish Amphiprion nigripes under natural conditions (28 - 30℃) at a lagoon of Agatti Island, Lakshadweep, India. The newly deposited fish egg was capsule-shaped and orange-red, with a (0.73 ± 0.04) mm3 yolk containing 5 - 10 fat globules. The embryonic development of fertilized eggs was divided into 26 stages and the time elapsing for each stage was recorded. Results showed that the cleavage was rapid, with the first division observed 1 h 20 min after fertilization. Blastulation occurred 4 h later, followed by gastrulation 12 h after fertilization, with a yolk volume of (0.61 ± 0.06) mm3. The organogenesis process started 22 h after fertilization when the blastopores closed and notochord formation began. The embryonic stage was recorded 24 h later, with the appearance of forebrain, midbrain, hindbrain, melanophores on yolk-sac and 22 somites, and a decreased yolk volume of (0.54 ± 0.08) mm3. Other organs developed well 31 h after fertilization, whereas the heart started beating and blood circulation began 78 h later. Red pigmentation (erytrophores) appeared 96 h after fertilization, with a small yolk volume of (0.22 ± 0.02) mm3. Mouth developed well and eyes were noticeable 120 h later, with head, pectoral fin and tail frequently moving 144 h after fertilization. The embryo reached the pre-hatching stage 168 h later and started to hatch after 170 - 180 h incubation. This study first detailed the embryonic development and yolk absorption of A. nigripes under natural conditions. 相似文献
489.
490.