检索结果-内蒙古大学图书馆

Study of soil moisture retrieval algorithms using multi-angular L-band brightness temperatures: Application to ESA's SMOS earth explorer opportunity mission

Study of soil moisture retrieval algorithms using multi-angu...

引用

Conference on Remote Sensing for Agriculture, Ecosystems and Hydrology V

作者： Monerris, A Vall-Ilossera, M Camps, A Univ Politecn Cataluna Dept Signal Theory & Commun E-08034 Barcelona Spain

ISBN: (纸本)0819451150

The European Space Agency's Soil Moisture and Ocean Salinity (SMOS) Earth Explorer Opportunity Mission will be launched in 2007. Its goal is the global and frequent measurement of soil moisture over the land and surface salinity over the sea, two key parameters governing the complex global climate. SMOS' single payload is the Microwave Imaging Radiometer by Aperture Synthesis (MIRAS), the first space-borne interferometric radiometer. SMOS will provide brightness temperature data over a wide range of incidence angles at vertical and horizontal polarizations (dual-polarimetric mode) or the full Stokes emission vector (full-polarimetric mode), from which the geophysical parameters will be derived. This paper focuses on the soil moisture retrieval problem using dual or full-polarimetric information. In this case, the brightness temperatures, as measured by the radiometer, depend mainly on five parameters descriptive of the surface under study: vegetation opacity and albedo, and soil surface temperature, roughness and moisture. Some of these parameters can be derived from other sensors or can be inferred from the multi-angular brightness temperatures themselves. Simulation results using the SMOS End-to-end Performance Simulator (SEPS) developed at the Universitat Politecnica de Catalunya (UPC) will be presented and discussed [1].

关键词： soil moisture vegetation microwave radiometry emissivity retrieval algorithms remote sensing

来源：评论

学校读者我要写书评

暂无评论

Cloud model evaluation using radiometric measurements from the airborne multiangle imaging spectroradiometer (AirMISR)

引用

REMOTE SENSING OF ENVIRONMENT 2007年第1-2期107卷 185-193页

作者： Ovtchinnikov, Mikhail Marchand, Roger T. Pacific NW Natl Lab Richland WA 99352 USA

Detailed information on cloud properties is needed to rigorously test retrieval algorithms for satellite and ground-based remote sensors. The inherent complexity of clouds makes this information difficult to obtain from observations alone and cloud resolving models (CRMs) are often used to generate synthetic datasets that can be used as proxies for real data. We test the ability of a CRM to reproduce the observed structure of low-level clouds detected by the Earth Observing System (EOS) validation program in north central Oklahoma on March 3, 2000. A threedimensional radiative transfer model is applied to bigh-resolution cloud fields generated by the CRM in order to simulate the top of atmosphere radiances. These synthetic radiances are then statistically compared with observations from the airborne Multiangle Imaging Spectro-Radiometer (AirMISR), flown on the NASA ER-2 high-altitude aircraft. Simulations match well the blue channel radiance distributions at oblique view angles but overestimate the minimum in reflectance at near-nadir viewing angles, The model reproduces correctly the angular change in the width of radiance distribution, as measured by the standard deviation but the change in skewness of these distributions is captured only qualitatively. The model biases are suggestive of the simulated cloud boundaries being too sharp and the distribution of the vertical liquid water path being too narrow. A power spectrum analysis shows a close agreement between simulations and observations including a break in the scaling properties of the radiance fields around 400 in. The scaling properties of the ID power spectrum of simulated radiance at smaller scales exhibit directional dependence not seen in corresponding observations. (c) 2007 Elsevier Inc. All rights reserved.

关键词： 3D radiative transfer AirMISR retrieval algorithms

来源：评论

学校读者我要写书评

暂无评论

Comparison of soil moisture retrieval algorithms using simulated HYDROS brightness temperatures

Comparison of soil moisture retrieval algorithms using simul...

引用

IEEE International Geoscience and Remote Sensing Symposium

作者： O'Neill, P Njoku, E Chan, T Crow, W Hsu, A Shi, JC NASA Goddard Space Flight Ctr Hydrol Sci Branch Greenbelt MD 20771 USA

ISBN: (纸本)0780387422

The HYDROS mission objective is to collect global scale measurements of the Earth's soil moisture and land surface freeze/thaw conditions, using it combined L band radiometer and radar system operating at 1.41 and 1.26 GHz, respectively. In order to examine how HYDROS soil moisture retrieval will he performed and how the retrieval accuracy will be impacted by Vegetation water content and surface heterogeneity, an observing system simulation experiment (OSSE) was conducted using a modeled geophysical domain in the south-central United States centered on the Arkansas-Red River basin for a one-month period in 1994. Three separate radiometer retrieval algorithms were evaluated: (1) a single-channel algorithm (H polarization), (2) a two-channel iterative algorithm, and (3) a two-channel reflectivity ratio algorithm. Analysis indicates that the HYDROS accuracy goal of 4% volumetric soil moisture can be met anywhere in the test basin except woodland areas. Nonlinear scaling of higher resolution ancillary vegetation data can adversely affect algorithm retrieval accuracies, especially in heavy tree areas on the east side of the basin.

关键词： soil moisture HYDROS retrieval algorithms microwave radiometery

来源：评论

学校读者我要写书评

暂无评论

ComRAD active/passive microwave measurement of tree canopies

ComRAD active/passive microwave measurement of tree canopies

引用

IEEE International Geoscience and Remote Sensing Symposium (IGARSS)

作者： O'Neill, Peggy Joseph, Alicia Nelson, Ross Lang, Roger Kurum, Mehmet Cosh, Michael Jackson, Thomas Spicknall, Mark NASA Goddard Space Flight Ctr Hydrospher & Biospher Sci Lab Greenbelt MD 20771 USA USDA ARS Beltsville Agr Res Ctr Hydrol & Remote Sensing Lab Beltsville MD 20705 USA George Washington Univ Dept Elect & Comp Sci Washington DC 20052 USA Univ Maryland CMREC Coll Agr & Nat Res Marlborough MA 20774 USA

ISBN: (纸本)9781424412112

The NASA/GSFC and George Washington University network analyzer-based multifrequency truck-mounted radar system has recently been upgraded with the addition of a dual-polarized 1.4 GHz total power radiometer. The system, now called ComRAD for Combined Radar/Radiometer, can function as a ground-based instrument simulator for L band space missions such as Hydros, Aquarius, and SMOS. In late summer 2006 ComRAD was deployed to the field to begin a series of coordinated active/passive L band measurements over small stands of deciduous and coniferous trees in order to improve our understanding of the microwave properties of trees and their effect on soil moisture retrieval algorithms. This paper describes the preliminary measurements obtained at the start of a three-year planned field measurement effort.

关键词： soil moisture retrieval algorithms microwave radiometry active/passive microwave trees tau-omega model

来源：评论

学校读者我要写书评

暂无评论

Extension of GPM dual-frequency iterative retrieval method with DSD-profile constraint

引用

IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING 2006年第2期44卷 328-335页

作者： Rose, CR Chandrasekar, V Colorado State Univ Ft Collins CO 80523 USA

A new Dual-Frequency Precipitation Radar (DPR) will be included on the Global Precipitation Measurement (GPM) core satellite which will succeed the highly successful Tropical Rainfall Measuring Mission satellite launched in 1997. New dual-frequency drop-size distribution (DSD) and rain-rate estimation algorithms are being developed to take advantage of the enhanced capabilities of the DPR. It has been shown previously that a backward-iteration algorithm can be embedded within a single-loop feedback model to retrieve the rain rate. However, the single-loop model is unable to correctly estimate DSD profiles for a significant portion of global median-volume-diameter, D-o and normalized DSD intercept parameter, N-w, combinations in rain because of a multiple-value solution space. For the remaining D-o, N-w pairs, another retrieval method is necessary. This paper proposes a dual-loop model, in which the intercept parameter, N-w, of the DSD is constrained in its vertical profile, to guide the algorithm to correct convergence. This allows an additional constraint on the DSD values estimated by the iterative algorithm and helps to retrieve correct DSD values in the regions where the iterative approach alone fails. To demonstrate feasibility of the proposed method, three test cases representative of many DSD and profile combinations are discussed. The first case is a constant vertical profile of the DSD parameters. The second case examines linear variation of the DSD parameters, and the third case examines how measurement error affects the retrieval process. In each case, the proposed constraint on the intercept parameter is implemented, and the results are discussed. Using the constraint, the dual-loop algorithm is able to retrieve reasonable values for the DSDs and rain-rate profiles and extend the convergence region of the algorithm.

关键词： drop-size distribution (DSD) estimation global precipitation measurement (GPM) retrieval algorithms

来源：评论

学校读者我要写书评

暂无评论

Using a priori information to improve soil moisture retrieval from ENVISAT ASAR AP data in semiarid regions

引用

IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING 2006年第4期44卷 900-912页

作者： Mattia, F Satalino, G Dente, L Pasquariello, G CNR Ist Studi Sist Intelligenti Automaz I-70126 Bari Italy

This paper presents a retrieval algorithm that estimates spatial and temporal distribution of volumetric soil moisture content, at an approximate depth of 5 cm, using multitemporal ENVISAT Advanced Synthetic Aperture Radar (ASAR) alternating polarization images, acquired at low incidence angles (i.e., from 15 degrees to 31 degrees). The algorithm appropriately assimilates a priori information on soil moisture content and surface roughness in order to constrain the inversion of theoretical direct models, such as the integral equation method model and the geometric optics model. The a priori information on soil moisture content is obtained through simple lumped water balance models, whereas that on soil roughness is derived by means of an empirical approach. To update prior estimates of surface parameters, when no reliable a priori information is available, a technique based solely on the use of multitemporal SAR information is proposed. The developed retrieval algorithm is assessed on the Matera site (Italy) where multitemporal ground and ASAR data were simultaneously acquired in 2003. Simulated and experimental results indicate the possibility of attaining an accuracy of approximately 5% in the retrieved volumetric soil moisture content, provided that sufficiently accurate a priori information on surface parameters (i.e., within 20% of their whole variability range) is available. As an example, multitemporal soil moisture maps at watershed scale, characterized by a spatial resolution of approximately 150 m, are derived and illustrated in the paper.

关键词： a priori information ENVISAT model inversion retrieval algorithms synthetic aperture radar (SAR) soil moisture soil roughness surface scattering

来源：评论

学校读者我要写书评

暂无评论

Using a priori information to improve soil moisture retrieval from ENVISAT ASAR AP data in semiarid regions

Using <i>a priori information</i> to improve soil moisture r...

引用

4th International Symposium on the retrieval of Bio- and Geophysical Parameters from SAR Data for Land Applications

作者： Mattia, F Satalino, G Dente, L Pasquariello, G CNR Ist Studi Sist Intelligenti Automaz I-70126 Bari Italy

关键词： a priori information ENVISAT model inversion retrieval algorithms synthetic aperture radar (SAR) soil moisture soil roughness surface scattering

来源：评论

学校读者我要写书评

暂无评论

Adaptive Web search: Evolving a problem that finds information

引用

IEEE INTELLIGENT SYSTEMS 2006年第5期21卷 72-77页

作者： Gordon, Michael Fan, Weiguo (Patrick) Pathak, Praveen Univ Michigan Ross Sch Business Ann Arbor MI 48109 USA Virginia Tech Blacksburg VA 24061 USA Univ Florida Warrington Coll Business Gainesville FL 32611 USA

Anyone who's used a computer to find information on the Web knows that the experience can be frustrating. Search engines are incorporating new techniques (such as examining document link structures) to increase effectiveness. However, searchers all too often face one of two outcomes: reviewing many more Web pages than they'd prefer or failing to find as much useful information as they really want. We introduce a new retrieval technique that exploits users' persistent information needs. These users might include business analysts specializing in genetic technologies, stockbrokers keeping abreast of wireless communications, and legislators needing to understand computer privacy and security developments. To help such searchers, we evolve effective search programs by using feedback based on users' judgments about the relevance of the documents they've retrieved. This approach uses genetic programming to automatically evolve new retrieval algorithms based on a user's evaluation of previously viewed documents

关键词： Internet genetic algorithms information needs relevance feedback search engines Web pages adaptive Web search document relevance feedback genetic programming retrieval algorithms retrieval technique user judgment feedback user persistent i Computer Security Internets relevance feedback information needs Search engines searcher Web pages Genetic Algorithm (GA) Web search

来源：评论

学校读者我要写书评

暂无评论

Observations of the ozone and nitrogen dioxide profiles in the TROICA-4 experiment

引用

ATMOSPHERIC REMOTE SENSING: EARTH'S SURFACE, TROPOSPHERE, STRATOSPHERE AND MESOSPHERE - II 2006年第12期37卷 2231-2237页

作者： Postylyakov, O. V. Belikov, I. B. Elansky, N. F. Elokhov, A. S. RAS LAGS AM Obukhov Inst Atmospher Phys Moscow 119017 Russia

To investigate the vast area of Russia, a mobile scientific facility based in a railway carriage was developed. It is capable to perform continues measurements being coupled in a passenger train traveling along railroads. It was first equipped with a spectrometer for remote sensing of ozone and nitrogen dioxide in the atmosphere for the transcontinental observations into the chemistry of the atmosphere-4 expedition performed from February 18 to March 5, 1998. A twilight DOAS method, which was applied for retrieval of the nitrogen dioxide profiles basing on spectral measurements at the visible wavelengths (434-451 nm), is described in the paper. Main features of a new algorithm for retrieval of the ozone profile and total content using the differential structure of the UV spectrum (310-335 nm) are presented. The ozone and nitrogen dioxide contents are obtained and shortly validated against available alternative data. (c) 2006 Published by Elsevier Ltd on behalf of COSPAR.

关键词： ozone nitrogen dioxide vertical distribution total content radiative transfer model retrieval algorithms DOAS technique air mass factors

来源：评论

学校读者我要写书评

暂无评论

An empirical line-by-line model for the infrared solar transmittance spectrum from 700 to 5000 cm^-1

引用

JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER 2006年第3期102卷 450-463页

作者： Hase, F. Demoulin, P. Sauval, A. J. Toon, G. C. Bernath, P. F. Goldman, A. Hannigan, J. W. Rinsland, C. P. Forschungszentrum Karlsruhe Inst Meteorol & Klimaforsch D-76021 Karlsruhe Germany Inst Astrophys & Geophys B-4000 Liege Belgium Observ Royal Belgique B-1180 Brussels Belgium Jet Propuls Lab Pasadena CA 91109 USA Univ Waterloo Dept Chem Waterloo ON N2L 3G1 Canada Univ Denver Dept Phys Denver CO 80208 USA Natl Ctr Atmospher Res Div Atmospher Chem Boulder CO 80303 USA NASA Langley Res Ctr Hampton VA 23681 USA

An empirical line-by-line model for the infrared solar transmittance spectrum is presented. The model can be incorporated into radiative transfer codes to allow fast calculation of all relevant emission and absorption features in the solar spectrum in the mid-infrared region from 700 to 5000 cm(-1). The transmittance is modelled as a function of the diameter of the field-of-view centered on the solar disk: the line broadening due to solar rotation as well as center-to-limb variations in strength and width are taken into account for stronger lines. Applications of the model presented here are in the fields of terrestrial remote sensing in the mid-infrared spectral region when the sun is used as radiation source or scattered solar radiation contributes to the measured signal and in the fields of atmospheric radiative transfer algorithms which compute the propagation of infrared solar radiation in the terrestrial atmosphere. (c) 2006 Elsevier Ltd. All rights reserved.

关键词： infrared spectroscopy atmospheric trace gases solar spectrum radiative transfer retrieval algorithms

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：