作者：
陈洪滨孙海冰王普才吕达仁LAGEO
Institute of Atmospheric PhysicsChinese Academy of Sciences.Beijing 100029
A collocated SSM/I and radiosonde measurement data set provided by the NASDA(Japan) was used to retrieve the total precipitable water(PW)over *** retrieval results obtained with several regression algorithms were comp...
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A collocated SSM/I and radiosonde measurement data set provided by the NASDA(Japan) was used to retrieve the total precipitable water(PW)over *** retrieval results obtained with several regression algorithms were compared against the radiosonde *** is shown that:(a)the routinely operational algorithm of Alishouse et al.(1990)yields significant underestimation in high PW regime and overestimation in low PW regime;(b)a cubic correction by Colton and Poe(1994)is not sufficient and globally improves slightly the retrieval results;and (c)the regression algorithm with the form of brightness temperature(T_b)function In (280-T_b) gives a little largely scattered retrievals in whole PW range but without considerable over-and underestimates in low and high PW *** improve the estimation of the oceanic precipitable water from the SSM/I measurements,a composite algorithm with different forms of T_b function in *** and high PW regimes is proposed and tested.
Instruments with very high spectral resolution are needed to sound stratospheric temperatures from satellite. Maximizing the contributions of the stratosphere to the upwelling radiance measured by a particular channel...
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ISBN:
(纸本)0819415902
Instruments with very high spectral resolution are needed to sound stratospheric temperatures from satellite. Maximizing the contributions of the stratosphere to the upwelling radiance measured by a particular channel can be achieved by using high spectral resolution channels positioned at strong carbon dioxide (CO2) line centers. In this paper, the techniques of stratospheric temperature sounding from satellite are briefly reviewed. The feasibility of high resolution stratospheric temperature sounding with the multi-order etalon sounder (MOES), a high resolution Fabry-Perot array spectrometer, is discussed. Our simulation studies indicate that stratospheric temperatures can be derived with a root-mean-square (RMS) error of about 2 - 3 K with MOES. A scenario to add MOES to the next generation high resolution infrared sounder (HIRS/3) currently under development with minimal cost is suggested. With its compact size and ruggedness, MOES is an ideal candidate as the stratospheric temperature sounding unit for small environmental satellite platforms.
A trie is a search tree obtained by merging the common suffixes of the key set. It has the advantage that all keys as prefixes of an input string can be retrieved with high speed. When the size of the key set is enlar...
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A trie is a search tree obtained by merging the common suffixes of the key set. It has the advantage that all keys as prefixes of an input string can be retrieved with high speed. When the size of the key set is enlarged, however, a problem arises, as the number of transitions increases, so too does the need for a large storage capacity. This paper proposes an algorithm that dynamically constructs DAWGs (Directed Acyclic Word Graphs) for the handling of dynamic key sets. It also solves the problem of the increasing number of transitions in the trie structure. The proposed method constructs a DAWG through the local separation of common suffixes for updating a key and, after finishing updating a key, the local transition merge of common suffixes. The proposed algorithm is theoretically evaluated and the data structure for the implementation is discussed. Experimental results show that the number of transitions in the DAWG is reduced by approx. 50 to 70% compared of that of the trie, for key sets of several thousands of fifty thousand elements, also the updating of the keys can be executed in a practical time for sets of less than ten thousand keys.
The high cost of page accessing implies a need for for more careful data organization in a paged memory than is typical of most inverted file and similar approaches to multi-key retrieval. This article analyses that c...
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The high cost of page accessing implies a need for for more careful data organization in a paged memory than is typical of most inverted file and similar approaches to multi-key retrieval. This article analyses that cost and proposes a method called multiple key hashing which attempts to minimize it. Since this approach is not always preferable to inversion, a combined method is described. The exact specifications of this combination for a file with given data and traffic characteristics is formulated as a mathematical program. The proposed heuristic solution to this program can often improve on a simple inversion technique by a factor of 2 or 3.
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