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  Subjects -> ELECTRONICS (Total: 159 journals)
Advances in Biosensors and Bioelectronics     Open Access   (Followers: 2)
Advances in Electronics     Open Access   (Followers: 4)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 6)
Advances in Microelectronic Engineering     Open Access   (Followers: 6)
Advances in Power Electronics     Open Access   (Followers: 10)
Aerospace and Electronic Systems, IEEE Transactions on     Hybrid Journal   (Followers: 105)
American Journal of Electrical and Electronic Engineering     Open Access   (Followers: 15)
Annals of Telecommunications     Hybrid Journal   (Followers: 5)
APL : Organic Electronics and Photonics     Hybrid Journal   (Followers: 2)
APSIPA Transactions on Signal and Information Processing     Open Access   (Followers: 6)
Archives of Electrical Engineering     Open Access   (Followers: 11)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 5)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 12)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 18)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 16)
Biomedical Instrumentation & Technology     Hybrid Journal   (Followers: 6)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 5)
BULLETIN of National Technical University of Ukraine. Series RADIOTECHNIQUE. RADIOAPPARATUS BUILDING     Open Access   (Followers: 2)
Bulletin of the Polish Academy of Sciences : Technical Sciences     Open Access  
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 14)
China Communications     Full-text available via subscription   (Followers: 4)
Circuits and Systems     Open Access   (Followers: 11)
Consumer Electronics Times     Open Access   (Followers: 5)
Control Systems     Hybrid Journal   (Followers: 36)
Edu Elektrika Journal     Open Access  
Electronic Design     Partially Free   (Followers: 23)
Electronic Markets     Hybrid Journal   (Followers: 5)
Electronic Materials Letters     Hybrid Journal   (Followers: 3)
Electronics     Open Access   (Followers: 10)
Electronics and Communications in Japan     Hybrid Journal   (Followers: 5)
Electronics Letters     Hybrid Journal   (Followers: 20)
Embedded Systems Letters, IEEE     Hybrid Journal   (Followers: 25)
Energy Harvesting and Systems : Materials, Mechanisms, Circuits and Storage     Hybrid Journal   (Followers: 3)
EPJ Quantum Technology     Open Access  
EURASIP Journal on Embedded Systems     Open Access   (Followers: 10)
Facta Universitatis, Series : Electronics and Energetics     Open Access  
Frequenz     Hybrid Journal   (Followers: 3)
Frontiers of Optoelectronics     Hybrid Journal   (Followers: 2)
Geoscience and Remote Sensing, IEEE Transactions on     Hybrid Journal   (Followers: 20)
Giroskopiya i Navigatsiya     Open Access  
Haptics, IEEE Transactions on     Hybrid Journal   (Followers: 3)
IEEE Antennas and Propagation Magazine     Hybrid Journal   (Followers: 24)
IEEE Antennas and Wireless Propagation Letters     Hybrid Journal   (Followers: 18)
IEEE Consumer Electronics Magazine     Full-text available via subscription   (Followers: 21)
IEEE Journal of Emerging and Selected Topics in Power Electronics     Hybrid Journal   (Followers: 17)
IEEE Journal of the Electron Devices Society     Open Access   (Followers: 5)
IEEE Power Electronics Magazine     Full-text available via subscription   (Followers: 16)
IEEE Transactions on Antennas and Propagation     Full-text available via subscription   (Followers: 19)
IEEE Transactions on Audio, Speech, and Language Processing     Hybrid Journal   (Followers: 15)
IEEE Transactions on Automatic Control     Hybrid Journal   (Followers: 35)
IEEE Transactions on Consumer Electronics     Hybrid Journal   (Followers: 19)
IEEE Transactions on Electron Devices     Hybrid Journal   (Followers: 10)
IEEE Transactions on Information Theory     Hybrid Journal   (Followers: 14)
IEEE Transactions on Power Electronics     Hybrid Journal   (Followers: 30)
IEEE Transactions on Signal and Information Processing over Networks     Full-text available via subscription   (Followers: 1)
IEICE - Transactions on Electronics     Full-text available via subscription   (Followers: 8)
IEICE - Transactions on Information and Systems     Full-text available via subscription   (Followers: 8)
IET Microwaves, Antennas & Propagation     Hybrid Journal   (Followers: 6)
IET Power Electronics     Hybrid Journal   (Followers: 16)
IET Wireless Sensor Systems     Hybrid Journal   (Followers: 10)
IETE Journal of Education     Open Access   (Followers: 2)
IETE Journal of Research     Open Access   (Followers: 11)
IETE Technical Review     Open Access   (Followers: 4)
Industrial Electronics, IEEE Transactions on     Hybrid Journal   (Followers: 17)
Industry Applications, IEEE Transactions on     Hybrid Journal   (Followers: 4)
Informatik-Spektrum     Hybrid Journal  
Instabilities in Silicon Devices     Full-text available via subscription  
Intelligent Transportation Systems Magazine, IEEE     Full-text available via subscription   (Followers: 4)
International Journal of Advanced Electronics and Communication Systems     Open Access   (Followers: 5)
International Journal of Advanced Research in Computer Science and Electronics Engineering     Open Access   (Followers: 22)
International Journal of Advances in Telecommunications, Electrotechnics, Signals and Systems     Open Access   (Followers: 3)
International Journal of Aerospace Innovations     Full-text available via subscription   (Followers: 13)
International Journal of Antennas and Propagation     Open Access   (Followers: 7)
International Journal of Applied Electronics in Physics & Robotics     Open Access   (Followers: 1)
International Journal of Biomedical Nanoscience and Nanotechnology     Hybrid Journal   (Followers: 5)
International Journal of Computational Vision and Robotics     Hybrid Journal   (Followers: 4)
International Journal of Computer & Electronics Research     Full-text available via subscription   (Followers: 1)
International Journal of Control     Hybrid Journal   (Followers: 14)
International Journal of Electronics     Hybrid Journal   (Followers: 2)
International Journal of Electronics & Data Communication     Open Access   (Followers: 4)
International Journal of Electronics and Telecommunications     Open Access   (Followers: 3)
International Journal of Granular Computing, Rough Sets and Intelligent Systems     Hybrid Journal   (Followers: 1)
International Journal of High Speed Electronics and Systems     Hybrid Journal  
International Journal of Image, Graphics and Signal Processing     Open Access   (Followers: 2)
International Journal of Microwave and Wireless Technologies     Hybrid Journal   (Followers: 1)
International Journal of Nano Devices, Sensors and Systems     Open Access   (Followers: 5)
International Journal of Nanoscience     Hybrid Journal  
International Journal of Numerical Modelling:Electronic Networks, Devices and Fields     Hybrid Journal   (Followers: 2)
International Journal of Power Electronics     Hybrid Journal   (Followers: 9)
International Journal of Review in Electronics & Communication Engineering     Open Access   (Followers: 3)
International Journal of Sensors, Wireless Communications and Control     Hybrid Journal   (Followers: 4)
International Journal of Systems, Control and Communications     Hybrid Journal   (Followers: 2)
International Journal of Wireless and Microwave Technologies     Open Access   (Followers: 1)
International Journal on Communication     Full-text available via subscription   (Followers: 13)
International Journal on Electrical and Power Engineering     Full-text available via subscription   (Followers: 10)
International Transaction of Electrical and Computer Engineers System     Open Access  
Journal of Biosensors & Bioelectronics     Open Access   (Followers: 2)
Journal of Advanced Dielectrics     Open Access   (Followers: 1)
Journal of Artificial Intelligence     Open Access   (Followers: 5)
Journal of Circuits, Systems, and Computers     Hybrid Journal   (Followers: 2)

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Journal Cover Selected Topics in Applied Earth Observations and Remote Sensing, IEEE Journal of
  [SJR: 1.632]   [H-I: 19]   [18 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1939-1404
   Published by Institute of Electrical and Electronics Engineers (IEEE) Homepage  [177 journals]
  • Front cover
    • Abstract: Presents the front cover for this issue of the publication.
      PubDate: Dec. 2015
      Issue No: Vol. 8, No. 12 (2015)
       
  • IEEE Journal of Selected Topics in Applied Earth Observations and Remote
           Sensing publication information
    • Abstract: Provides a listing of the editors, board members, and current staff for this issue of the publication.
      PubDate: Dec. 2015
      Issue No: Vol. 8, No. 12 (2015)
       
  • IEEE Transactions on Geoscience and Remote Sensing institutional listings
    • Abstract: The GRSS Society invites application for Institutional Listings from firms interested.
      PubDate: Dec. 2015
      Issue No: Vol. 8, No. 12 (2015)
       
  • IEEE Journal of Selected Topics in Applied Earth Observations and Remote
           Sensing Information for Authors
    • Abstract: These instructions give guidelines for preparing papers for this publication. Presents information for authors publishing in this journal.
      PubDate: Dec. 2015
      Issue No: Vol. 8, No. 12 (2015)
       
  • Table of Contents
    • Pages: 5397 - 5397
      Abstract: Presents the table of contents for this issue of the publication.
      PubDate: Dec. 2015
      Issue No: Vol. 8, No. 12 (2015)
       
  • Foreword to the Special Issue on Status of Aquarius/SAC-D Mission
           Calibration/Validation and Retrieval Algorithms
    • Authors: Le Vine; D.M.;Yueh, S.;Brown, S.;Lagerloef, G.S.E.;Rabolli, M.;
      Pages: 5398 - 5400
      Abstract: The papers in this special section focus on the Aquarius/SAC-D observatory, a partnership between the USA Space Agency, NASA, and the Argentine Space Agency, CONAE (Comisi??n Nacional de Actividades Espaciales). Aquarius/SAC-D observatory was launched on June 10, 2011 from Vandenberg Air Force Base, Vandenberg, CA, USA. The observatory included several instruments and two of them are related to the primary goal of the mission. The primary goal of the mission was mapping ocean surface salinity, and mission parameters (e.g., the orbit and repeat cycle) were tuned to this objective. From the NASA perspective, this was a pathfinder mission to demonstrate the technology of remote sensing of sea urface salinity from space and to provide data for understanding the role of salinity in Earth???s water cycle, and Aquarius was the primary instrument. But the mission was international in scope and also fit the needs of the Argentine plans for space applications.
      PubDate: Dec. 2015
      Issue No: Vol. 8, No. 12 (2015)
       
  • Status of Aquarius/SAC-D and Aquarius Salinity Retrievals
    • Authors: Le Vine; D.M.;Dinnat, E.P.;Meissner, T.;Yueh, S.H.;Wentz, F.J.;Torrusio, S.E.;Lagerloef, G.;
      Pages: 5401 - 5415
      Abstract: Aquarius was launched in June 2011 to monitor the global salinity field in the open ocean. This radiometer/scatterometer (i.e., passive/active) instrument is part of the Aquarius/SAC-D mission, a partnership between the USA and Argentina. In general, the observatory and instruments have functioned well with mostly minor issues. Aquarius has been operating successfully since being turned on August 25, 2011. The quality of the salinity retrieval has improved continuously and is approaching the accuracy goal of 0.2 psu (monthly global RMS). The maps produced by Aquarius show the global structure and dynamic features of the salinity field and, now after 3 years of operations, data are available to give a first look at the interannual changes in sea surface salinity. An improved salinity product, Version 3.0, has been released to the public (June 2014) and includes significant refinements in the retrieval algorithm such as reduced ascending/descending differences and improved calibration. Additional data such as global maps of soil moisture and maps of RFI are also available.
      PubDate: Dec. 2015
      Issue No: Vol. 8, No. 12 (2015)
       
  • Aquarius L-Band Microwave Radiometer: 3 Years of Radiometric Performance
           and Systematic Effects
    • Authors: Piepmeier; J.R.;Hong, L.;Pellerano, F.A.;
      Pages: 5416 - 5423
      Abstract: The Aquarius L-band microwave radiometer is a three-beam pushbroom instrument designed to measure sea-surface salinity. Results are analyzed for performance and systematic effects over three years of operation. The thermal control system maintains tight temperature stability promoting good gain stability. The gain spectrum exhibits expected orbital variations with $1/{f}$ noise appearing at longer time periods. The on-board detection and integration scheme coupled with the calibration algorithm produce antenna temperatures with NEDT ${
      PubDate: Dec. 2015
      Issue No: Vol. 8, No. 12 (2015)
       
  • Aquarius Scatterometer Calibration
    • Authors: Fore; A.G.;Neumann, G.;Freedman, A.P.;Chaubell, M.J.;Tang, W.;Hayashi, A.K.;Yueh, S.H.;
      Pages: 5424 - 5432
      Abstract: In this paper, we discuss the Aquarius scatterometer calibration, starting with the instrument calibration. We examine the stability of Aquarius as quantified using the loop-back power and estimated receiver gain to shown Aquarius has been extremely stable to order 0.1 dB since mission start. We show the temperatures of scatterometer components not contained in the loop-back path have been controlled precisely to 0.5°C to minimize any temperature-dependent losses. Combined, these results show Aquarius produces accurate $sigma_0$ over the mission lifetime. In the next section, we discuss the stability as quantified using external models and again show stability to order 0.1 dB in very good agreement with instrument-only methods. Then, we discuss the methods used to absolutely calibrate Aquarius $sigma_0$ with respect to previous L-band radar systems. We show that Aquarius is relatively calibrated to order 0.1 dB for copolarization channels and better than 0.2 dB for cross-polarization channels. Finally, we discuss the calibration of the Aquarius wind speed product. We compare the Aquarius wind speed with radiometer wind speed products, other radar scatterometers, and numerical weather products. We show that the Aquarius wind speed product is on par with previous scatterometers in data quality.
      PubDate: Dec. 2015
      Issue No: Vol. 8, No. 12 (2015)
       
  • Aquarius L-band Radiometers Calibration Using Cold Sky Observations
    • Authors: Dinnat; E.P.;Le Vine, D.M.;Piepmeier, J.R.;Brown, S.T.;Hong, L.;
      Pages: 5433 - 5449
      Abstract: An important element in the calibration plan for the Aquarius radiometers is to look at the cold sky. This involves rotating the satellite 180° from its nominal Earth viewing configuration to point the main beams at the celestial sky. At L-band, the cold sky provides a stable, well-characterized scene to be used as a calibration reference. This paper describes the cold sky calibration for Aquarius and how it is used as part of the absolute calibration. Cold sky observations helped establish the radiometer bias, by correcting for an error in the spillover lobe of the antenna pattern, and monitor the long-term radiometer drift.
      PubDate: Dec. 2015
      Issue No: Vol. 8, No. 12 (2015)
       
  • CONAE Microwave Radiometer (MWR) Counts to Tb Algorithm and On-Orbit
           Validation
    • Authors: Ghazi; Z.;Jones, W.L.;Jacob, M.M.;Santos-Garcia, A.;Bruscantini, C.A.;
      Pages: 5450 - 5461
      Abstract: The Aquarius/SAC-D, International Earth Science Satellite Mission, is a collaboration between NASA and the Argentine Space Agency (Comisión Nacional de Actividades Espaciales, CONAE) that was launched on June 10, 2011 to provide scientists with monthly global maps of sea surface salinity (SSS) to understand the Earth’s hydrological cycle and to investigate global climate change. This paper concerns the microwave radiometer (MWR), a CONAE science instrument developed to provide simultaneous and spatially collocated environmental measurements that complement the prime L-band radiometer/scatterometer sensor (Aquarius) for measuring SSS. MWR is a 3-channel (23.8-GHz H-pol and 36.5-GHz V- and H-pol) passive microwave instrument that measures the Earth’s brightness temperature (Tb). This paper describes the MWR counts to Tb algorithm (V6.0) and presents results of the on-orbit Tb validation using intersatellite radiometric calibration with the Naval Research Laboratory’s WindSat (WS) satellite radiometer. In addition, an alternative MWR counts to Tb algorithm (V7.0) is presented that normalizes the MWR Tbs to WS. This latter version (V7.0) has the advantage of removing MWR time-varying radiometric calibration biases between antenna beams and channels as verified by on-orbit comparisons with WS.
      PubDate: Dec. 2015
      Issue No: Vol. 8, No. 12 (2015)
       
  • Land Intercalibration and Drift Monitoring of MWR Radiometer on Board
           SAC-D/Aquarius
    • Authors: Bruscantini; C.A.;Maas, M.;Grings, F.;Karszenbaum, H.;
      Pages: 5462 - 5467
      Abstract: The microwave radiometer (MWR) on board the SAC-D/Aquarius mission is a Dicke radiometer operating at 23.8 (H-Pol) and 36.5 GHz (H/V-Pol), which can provide ancillary data for the various retrievals to be performed with Aquarius regarding ocean and land applications. In this study, we report calibration results obtained by a land cross-calibration between Windsat and MWR. Moreover, MWR drifts were monitored using vicarious cold methodology. Results were generated for the 2011–2012 period using version V5.0 S of MWR data. MWR and Windsat cross-calibration was carried out over selected homogeneous targets which include tropical and boreal forests, desert, grassland, and the Sahel. As a result, biases were identified and corrections were proposed. Drifts in MWR observations were identified by implementing the vicarious cold method, which is a statistical approach that estimates the coldest value of the brightness temperature (Tb) (over ocean) histogram. Time series of such cold values are closely related to drifts in the instrument. In general, it was observed that MWR drifts tend to stabilize within 1 K after June 2012, when the software of the on-board computer was updated.
      PubDate: Dec. 2015
      Issue No: Vol. 8, No. 12 (2015)
       
  • MWR Smear Effect: A Counts-Level Empirical Correction and Possible Causes
    • Authors: Labanda; M.;Jacob, M.M.;Farrar, S.;Masuelli, S.;Jones, L.;
      Pages: 5468 - 5473
      Abstract: The microwave radiometer (MWR) is a Dicke radiometer on board of the Aquarius (AQ)/SAC-D satellite. It was developed by Argentine space agency, Comisión Nacional De Actividades Espaciales (CONAE), and operates at 23.8 and 36.5 GHz frequencies. After MWR initially turned on, the first brightness temperature ( $text{T}_{text{B}}$ ) measurements were obtained, observing an anomalous recurrent effect when analyzing land/water crossings. The effect is present for all frequencies and earth incidence angles (EIAs) and results in a smearing of $text{T}_{text{B}}$ observations near strong contrast radiometric scenes. This paper summarizes the main features and discoveries around this anomaly leading to a general description of the problem: coupling of sequential MWR measurements. Consequently, an empirical correction algorithm is derived and validated. Also, possible causes are investigated.
      PubDate: Dec. 2015
      Issue No: Vol. 8, No. 12 (2015)
       
  • Rain-Induced Near Surface Salinity Stratification and Rain Roughness
           Correction for Aquarius SSS Retrieval
    • Authors: Tang; W.;Yueh, S.H.;Hayashi, A.;Fore, A.G.;Jones, W.L.;Santos-Garcia, A.;Jacob, M.M.;
      Pages: 5474 - 5484
      Abstract: The effect of rain on surface salinity stratification is analyzed to develop a rain roughness correction scheme to reduce the uncertainty of Aquarius sea surface salinity (SSS) retrieved under rainy conditions. Rain freshwater inputs may cause large discrepancies in salinity measured by Aquarius at 1–2 cm within the surface and the calibration reference SSS from HYCOM ( $text{SSS}_text{HYCOM}$ ) a few meters below the surface. We used the rain impact model (RIM) to adjust $text{SSS}_text{HYCOM}$ to reflect near surface salinity stratification caused by freshwater inputs accumulated from rain events that occurred over the past 24 h before Aquarius measurements ( $text{SSS}_text{RIM}$ ). When calibrated with $text{SSS}_text{RIM}$ , the residuals, i.e., the difference between measured and model predicted brightness temperature ${{text T}_{text B}}$ , are considered as rain-induced roughness. It was found that rain-induced roughness is larger at lower wind speeds, and decreases as wind increases. The Combined Active Passive algorithm is used to retrieve SSS with ( $text{SSS}_text{{CAP}_{RC}}$ ) or without ( $text{SSS}_text{CAP}$ ) rain roughness correction. We find that the simultaneously retrieved wind speed with rain roughness correction has significantly improved agreement with the NCEP wind speed with the rain-dependent bias reduced, self-justifying our rain correction approach. SSS retrieved is validated with salinity measured by drifters at a depth o- 45 cm. The difference between satellite retrieved and in situ salinity increases with rain rate. With rain-induced roughness accounted for, the difference between satellite retrieval and drifter increases with rain rate with slope of $- {0}.{184};{text{psu}}$ ${left({{text{mm}};{text{h}^{ - mathbf{1}}}} right)^{ - mathbf{1}}}$ , representing the salinity stratification between the two depths (1–2 cm versus 45 cm).
      PubDate: Dec. 2015
      Issue No: Vol. 8, No. 12 (2015)
       
  • An Algorithm for Sea Surface Wind Speed from SAC-D/Aquarius Microwave
           Radiometer
    • Authors: Tauro; C.B.;Hejazin, Y.;Jacob, M.M.;Jones, W.L.;
      Pages: 5485 - 5490
      Abstract: This paper provides the description of an ocean wind speed retrieval algorithm developed for the SAC-D/Aquarius microwave radiometer’s (MWR). Empirical model coefficients are derived using MWR brightness temperature at 36.5 GHz H- and V-pol with collocated numerical weather prediction (NWP) model estimates of oceanic and atmospheric environmental parameters. A unique feature of this algorithm is that it incorporates NWP estimates of wind direction to correct the MWR surface brightness temperatures before simultaneously retrieving atmospheric transmissivity, an isotropic ocean surface wind speed. Comprehensive on-orbit validation was conducted using 6 months of MWR wind speed measurements with collocated satellite ocean wind speed retrievals, provided by Remote Sensing Systems, Inc. These results indicate that MWR surface wind retrieval data are quite acceptable for scientific analysis.
      PubDate: Dec. 2015
      Issue No: Vol. 8, No. 12 (2015)
       
  • Impact of Ocean Wave Height on L-band Passive and Active Microwave
           Observation of Sea Surfaces
    • Authors: Yueh; S.H.;Tang, W.;Fore, A.G.;Hayashi, A.;
      Pages: 5491 - 5499
      Abstract: The impact of ocean waves on L-band brightness temperatures and backscatter from the ocean surface was analyzed using Aquarius data. Matchups of Aquarius data with significant wave height (SWH) from National Oceanic and Atmospheric Administration (NOAA) WaveWatch3 reanalysis and the ocean surface wind are generated. We perform the analysis using two different wind speed products: special sensor microwave imager/sounder (SSMI/S) and National Center for Environmental Prediction (NCEP) operational data. Interestingly, the influence of SWH manifests itself differently for these two wind speed products. Conditionally, averaged normalized radar cross-section ( ${sigma _0}$ ) and brightness temperatures ( ${text{T}}_{text{B}}$ ) by NCEP wind speed show strong influence by SWH over the entire range of NCEP wind speeds with a larger impact at lower wind speeds. However, performing the same analysis conditioned on the SSMI/S wind speed, the conclusion becomes entirely different: the SWH effects appear small at low wind speeds ( ${
      PubDate: Dec. 2015
      Issue No: Vol. 8, No. 12 (2015)
       
  • A Roughness Correction for Aquarius Sea Surface Salinity Using the CONAE
           MicroWave Radiometer
    • Authors: Hejazin; Y.;Jones, W.L.;Santos-Garcia, A.;Jacob, M.M.;El-Nimri, S.F.;
      Pages: 5500 - 5510
      Abstract: Aquarius (AQ)/SAC-D is a joint National Aeronautics and Space Administration (NASA)/Comisión Nacional de Actividades Espaciales (CONAE; Argentine Space Agency) Earth Sciences satellite mission to measure global sea surface salinity (SSS), using a L-band radiometer/scatterometer that measures ocean brightness temperature (Tb) and radar backscatter (sigma-0). The application of L-band radiometry to retrieve SSS is a difficult task; therefore, precise Tb corrections are necessary to obtain accurate measurements. One of the major error sources is the effect of ocean roughness that “warms” the ocean Tb. The baseline approach, to provide this ocean roughness correction, uses the AQ radar scatterometer measurement of ocean sigma-0 to infer the radiometric excess ocean emissivity. In contrast, this paper develops an alternate approach for the AQ ocean roughness correction using the MicroWave Radiometer (MWR) Tb measurements at Ka-band. The theoretical basis of this MWR ocean roughness correction algorithm is described, which translates these Ka-band measurements to L-band to remove the AQ Tb errors that are caused by ocean wind speed and direction. MWR ocean roughness correction results are compared with corresponding results from the AQ scatterometer method. Also, AQ SSS retrievals are presented using both sets of roughness corrections that demonstrate the relative effectiveness of the MWR and AQ scatterometer approaches.
      PubDate: Dec. 2015
      Issue No: Vol. 8, No. 12 (2015)
       
  • First Evaluation of Aquarius Soil Moisture Products Using In
           Situ
    Observations and GLDAS Model Simulations
    • Authors: Li; D.;Zhao, T.;Shi, J.;Bindlish, R.;Jackson, T.J.;Peng, B.;An, M.;Han, B.;
      Pages: 5511 - 5525
      Abstract: L-band satellite remote sensing is one of the most promising techniques for global monitoring of soil moisture (SM). In addition to soil moisture and ocean salinity (SMOS) SM products, another global SM product has been developed using Aquarius, which is the first operational active/passive L-band satellite sensor. The spatial resolution of Aquarius SM products is about 100 km, which presents more challenges to the ground-based validation. This study explores approaches to validate and evaluate the Aquarius SM products in terms of their spatial and temporal distributions, through synergistic use of in situ measurements and model products from the global land data assimilation system (GLDAS). A dense soil moisture/temperature monitoring network over the central Tibetan plateau (CTP-SMTMN) and sparse stations from the soil climate analysis network (SCAN) over United States are used for the reliability assessment of Aquarius SM products. Results show that the Aquarius SM captures the spatial–temporal variability of CTP-SMTMN reference dataset with an overall RMSD of $0.078;{text{m}^3}cdot{text{m}^{ - 3}}$ and correlation coefficient of 0.767. The comparison results with reference to SCAN datasets suggest that the RMSD can reach to the target value of $0.04;{text{m}^3}cdot{text{m}^{ - 3}}$ over specific stations, but the impacts from different orbits, seasons, and land cover types are also found to be significant. The comparison between Aquarius retrievals and GLDAS/common land model (CLM) simulations presents a general well statistical agreement with correlation coefficients above 0.5 for most terrestrial areas. These results are considered to support the use of Aquarius SM products in future applications.
      PubDate: Dec. 2015
      Issue No: Vol. 8, No. 12 (2015)
       
  • L-Band Radar Soil Moisture Retrieval Without Ancillary Information
    • Authors: Bruscantini; C.A.;Konings, A.G.;Narvekar, P.S.;McColl, K.A.;Entekhabi, D.;Grings, F.M.;Karszenbaum, H.;
      Pages: 5526 - 5540
      Abstract: A radar-only retrieval algorithm for soil moisture mapping is applied to L-band scatterometer measurements from the Aquarius. The algorithm is based on a nonlinear relation between L-band backscatter and volumetric soil moisture and does not require ancillary information on the surface, e.g., land classification, vegetation canopy, surface roughness, etc. It is based on the definition of three limiting cases or end-members: 1) smooth bare soil; 2) rough bare soil; and 3) maximum vegetation condition. In this study, an estimation method is proposed for the end-member parameters that is iterative and only uses space-borne measurements. The major advantages of the algorithm include an analytic formulation (direct inversion possible), and the fact that there is no requirement for ancillary information. Ancillary data often misclassify the surface and the parameterizations linking surface classification to model parameter values are often highly uncertain. The retrieval algorithm is tested using 3 years of space-borne scatterometer observations from the Aquarius/SAC-D. Retrieved soil moisture accuracy is assessed in several ways: comparison of global spatial patterns with other available soil moisture products (two reanalysis modeling products and retrievals based on the Aquarius radiometer), extended triple collocation (ETC) and time series analysis over selected target areas. In general, low bias and standard deviation are observed with levels comparable to independent radiometer-based retrievals. The errors, however, increase across areas with high vegetation density. The results are promising and applicable to forthcoming L-band radar missions such as SMAP-NASA (2015) and SAOCOM-CONAE (2016).
      PubDate: Dec. 2015
      Issue No: Vol. 8, No. 12 (2015)
       
  • Mapping Offshore Winds Around Iceland Using Satellite Synthetic Aperture
           Radar and Mesoscale Model Simulations
    • Authors: Hasager; C.B.;Badger, M.;Nawri, N.;Furevik, B.R.;Petersen, G.N.;Bjornsson, H.;Clausen, N.;
      Pages: 5541 - 5552
      Abstract: The offshore wind climate in Iceland is examined based on satellite synthetic aperture radar (SAR), coastal meteorological station measurements, and results from two atmospheric model data sets, HARMONIE and NORA10. The offshore winds in Iceland are highly influenced by the rugged coastline. Lee effects, gap flow, coastal barrier jets, and atmospheric gravity waves are not only observed in SAR, but are also modeled well from HARMONIE. Offshore meteorological observations are not available, but wind speed and wind direction measurements from coastal meteorological masts are found to compare well to nearby offshore locations observed by SAR. More than 2500 SAR scenes from the Envisat ASAR wide swath mode are used for wind energy resource estimation. The wind energy potential observed from satellite SAR shows high values above ${1000};{Wm}^{ - {2}}$ in coastal regions in the south, east, and west, with lower values in the north. The most promising region for wind energy production is the southwestern coastal region.
      PubDate: Dec. 2015
      Issue No: Vol. 8, No. 12 (2015)
       
  • Elevation-Dependent Frequency-Domain Imaging for General Bistatic SAR
    • Authors: Liu; Z.;Dai, C.;Zhang, X.;Yang, J.;
      Pages: 5553 - 5564
      Abstract: In the general bistatic SAR (GBiSAR) for imaging of fluctuant terrains, e.g., hilly or mountainous areas, the diverse platform’s types and various geometric configurations of the GBiSAR system lead to a 3-D spatial variance with complicated couplings and significant variation in its frequency-domain matching filter (FDMF) kernel, which brings great challenges to the conventional frequency-domain (FD) imaging techniques. In this paper, an efficient FD imaging algorithm is proposed to compensate the 3-D spatial variance. First, the discrete linear least square (DLLS) is employed to simplify the FDMF kernel. Then a linear mapping converts the spatial-frequency couplings to irregular real numbers. The scaled 2-D nonuniform fast Fourier transform of type 3 (2-D NUFFT-3) is finally performed to speed up the compensation of the 3-D spatial variance. The computational complexity of the algorithm is O(MNlogMN) where MN is the number of the image pixels. The proposed algorithm is straightforward regardless the complicated couplings. In addition, it is robust to accommodate the variation of the FDMF kernel phase. Simulations on several BiSAR systems show that the proposed algorithm can yield high-quality images with good focusing performance and fine geometric registration performance for diverse BiSAR configurations within a widescope fluctuant terrain.
      PubDate: Dec. 2015
      Issue No: Vol. 8, No. 12 (2015)
       
  • Seasonal Differences in Forest Height Estimation From Interferometric
           TanDEM-X Coherence Data
    • Authors: Olesk; A.;Voormansik, K.;Vain, A.;Noorma, M.;Praks, J.;
      Pages: 5565 - 5572
      Abstract: This paper demonstrates the use of X-band bistatic synthetic aperture radar (SAR) interferometric coherence for retrieving tree height of coniferous and deciduous forests during leaf-off season in early spring and leaf-on period in summer. TerraSAR-X add-on for Digital Elevation Measurements (TanDEM-X) HH and VV polarization channel coherence images were studied for over 249 ha of forests in Estonia and compared against light detection and ranging (LiDAR) and forest registry field inventory data. Strong correlation was found between interferometric coherence magnitude and LiDAR measured average tree height, especially for winter period. The regression models show the strongest correlation between pine stand heights and single-polarization interferometric coherence, where the correlation coefficients ( ${{text{r}}^{2}}$ ) range between 0.75 and 0.97. The highest correlation for mixed deciduous tree stands was found during leaf-off period with ${{text{r}}^{2}}$ ranging from 0.87 to 0.94, whereas leaf-on period resulted in ${{text{r}}^{2}}$ from 0.58 to 0.75. Strong correlations were also found for spruce trees with ${{text{r}}^{2}}$ between 0.54 and 0.83. Moreover, a simple semiempirical model based on random volume over ground model framework was constructed to describe the relation between the forest height and interferometric coherence. Also, the seasonal variability of the correlation was studied. Our results demonstrate that under Northern-European conditions, seasonal changes have a significant effect for deciduous trees as standard deviations dropped from 1.34–1.78 m during leaf-off conditions to 2.22–3.16 m for leaf-on conditions. Thus, height estimat- on of deciduous stands requires leaf-off conditions for accurate coherence-based height retrieval. Correlation coefficients for pine stands were unvarying across different weather conditions and least affected by the season. The observed strong sensitivity of interferometric coherence to forest height makes it feasible for estimating canopy height for boreal and deciduous forests in both summer and winter conditions. The estimation algorithm works best for coniferous forests.
      PubDate: Dec. 2015
      Issue No: Vol. 8, No. 12 (2015)
       
 
 
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