A SSM/I and collocated radiosonde observation data set provided by the NASDA(Japan) was used to retrieve the total precipitable water (PW) over oceans. The retrieval results obtained with several regression algorithms were compared to the radiosonde measurements. It is shown that : (a) the routinely operational algorithm of Alishouse et al.(1990) yields significant underestimates in high PW regime and overestimates in low PW regime; (b) a cubic correction by Colton and Poe (1994) is not sufficient and globally improves very slightly the retrieval results; and (c) the regression algorithm with the form of brightness temperature (TB) function ln(280-TB) seems to give a little largely scattered retrievals but without noticeable over-and underestimates in low and high PW regimes. To improve the estimation of the oceanic precipitable water from the SSM/I TB measurements, a composite algorithm with different forms of TB function in low, medium and high PW regimes is proposed and tested.
In vegetation district,as a result of that the plant absorb Au and associated elements of lock and soil,the contents of Au and associated elements,pigment,water surface temperature,and cells structure in leaves occur variations,even the plant cause abnormality of biogeochemical effect,thus it appear abnormality in the spectral information of TM image.This paper takes the Hetai gold deposit as researh target.According to these feature and difference,we extract the abnormal feature of biogeochemical effect using remote sensing image processing,and enclose the remote sensing abnormal areas of mineral,thus we achieve the goal to find hidden deposits in vegetation.Meanwhile we go on looking for mineral deposits in western Guangdong and Heilongjiang,and evaluate rapid two the remote sensing abnormal areas.The results proved that remote sensing technology is a rapid,accurate and economical method for applying to practice of looking for mineral deposits in vegetation district,the new way is explored to be looking for hidden deposits in vegetation district.
It was interesting to discuss the relationship between land-cover condition and temperature clearly with Landsat/TM image data. This paper classified the landcovers in Tokyo area with TM image band 1,2,3,4,5,and got the temperature distribution in the same area with TM image band 6 by applying image processing. The result proved that the correspondence between land-covers and temperature distribution was high.
Characteristic matrix of multi-detector imaging spectrum system in its spacial sampling direction is derived firstly from the LSF of one-detector system by numerical calculation,using it we can obtain the output of system under known sine wave input,it is also proved that there exists no MTF in this direction of the system,but the contrast transfer function will reflect the transfer performance of system to sine signals with different periods well.
In this paper, the new technique of along track scanning radiometer(ATSR) is described in detail. Then reviewing the application of ATSR data over sea and land surface.Meanwhile, the possible problems on the application through the land surface are discussed here. It is indicated the dual-angle,dual-channel scanning of ATSR not only corrects the atmospheric effects successfully, but also provides the useful information about atmosphere status and scanned areas. It is no doubt that ATSR data will be used widely in the future.
Similarity coefficient cluster analysis is used to deal with 53 rock laboratorial reflectance spectra from the Wulashan mountain,the Inner Mongolia Autonomous Region.This method classifies the samples based on analysis between vectors in N-dimensional vector space,and reveals total similarity difference o f rock spectral shape in 0.4～2.5μm.Results show that the reflective properties of rock are different from the properties of petrographic classification.The paper gives a method to classify rock according to similarity ofspectral shape,meanwhile it analies the advantages and disadvantages of Spectral Angle Mapping(SAM)in imaging spectrametrey,and provides a meaningful spectral basis for image processing.
In this paper,principal component analysis(PCA)used to fuse Landsat TM with SAR image is discussed.The images generated by PCA fusion method have higher spatial resolution while maintaining the basic spectral contents of the original TM images.Comparison are made qualitatively and quantitatively with HIS method.The PCA fusion method distorts the spectral characteristics less than the HIS method does,so their capabilites of the images generated by the PCA fusion method are improved both in interpretation and in measurement.They will be more widely applied in practice.
It is indicated that atmospheric correction for optical remote sensing is one of the problems to be solved in urgent need for quantitative remote sensing.The correction results depend on which we employ and their accuracy,such as the model of atmospheric particles,the hypothesis of surface properties,as well as the theory of radiance transfer.Scientists have to balance between a complicated theory and an accurate result.Then,an analysis and summary to those effective factors is submitted comprehensively and in detail.The developing history and the current status of the related researches are described,as well as the direct and indirect correction methods are introduced.It is also reminded that the theory and method of atmospheric correction need a further advance and complement considering their defects in practice.Finally,we conclude a strategy for the atmospheric correction.
Conventional observations of sea surface wind speeds are provided by ships,buoys, coastal or island station,but they have limits in time and space which hinder further study of vast ocean area.Satellite remote sensing,especially microwave remote sensing,is becoming main method to measure sea surface wind with the development of space technology since wind speeds derived from satellite microwave sensors have the advantages in spatial and temporal resolutions.There are mainly three kinds of microwave sensors used to detect sea surface winds at present,they are scatterometer,radiometer and altimeter.The properties and features of these three microwave sensors are compared,and two methods to obtain the sea surface wind fields in large scale,one of which is comprehensive analysis of multi-source remote sensing information,another is numerical assimilation are indicated in this paper.
Hyperspectral remote sensing data,compared with wide-band remote sensing data,has the advantage of high spectral resolution.Hyperspectral remote sensing information processing involves radiometric calibration, image enhancement, pixel unmixing, spectral matching,and derivative spectral technology,etc. Hyperspectral remote sensing has been used to analyze Normalized Difference Vegetation Index(NDVI),Leaf Area Index(LAI)and Absorbed Photosynthetically Active Radiation(APAR).In vegetation monitoring,it has been used to detect the canopy biochemical characteristics,to analyze the vegetation parameters and to monitor the vegetation growth state.An detailed review on recent works focused on the above several points is given in the paper.Finally,the author s viewpoint on the future development of image spectrometry in vegetation monitoring is stressed.
