The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
C S Ruf - One of the best experts on this subject based on the ideXlab platform.
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wind speed retrieval algorithm for the cyclone global navigation Satellite System cygnss mission
IEEE Transactions on Geoscience and Remote Sensing, 2016Co-Authors: Maria Paola Clarizia, C S RufAbstract:A retrieval algorithm is presented for the Level 2 ocean surface wind speed data product of the Cyclone Global Navigation Satellite System (CYGNSS) mission. The algorithm is based on the approach described by Clarizia et al ., 2014. The approach is applied to the specific orbital measurement geometry, antenna, and receiver hardware characteristics of the CYGNSS mission. Several additional processing steps have also been added to improve the performance. A best weighted estimator is used to optimally combine two different partially correlated estimates of the winds by taking their weighted average. The optimal weighting dynamically adjusts for variations in the signal-to-noise ratio of the observations that result from changes in the measurement geometry. Variations in the incidence angle of the measurements are accounted for by the use of a 2-D geophysical model function that depends on both wind speed and incidence angle. Variations in the propagation time and signal Doppler shift at different measurement geometries affect the instantaneous spatial resolution of the measurements, and these effects are compensated by a variable temporal integration of the data. In addition to a detailed description of the algorithm itself, the root-mean-square wind speed retrieval error is characterized as a function of the measurement geometry and the wind speed using a detailed mission end-to-end simulator.
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the nasa ev 2 cyclone global navigation Satellite System cygnss mission
IEEE Aerospace Conference, 2013Co-Authors: C S Ruf, Scott Gleason, Zorana Jelenak, Stephen J Katzberg, A J Ridley, Randy Rose, J Scherrer, Valery U ZavorotnyAbstract:The NASA EV-2 Cyclone Global Navigation Satellite System (CYGNSS) is a spaceborne mission focused on tropical cyclone (TC) inner core process studies. CYGNSS attempts to resolve the principle deficiencies with current TC intensity forecasts, which lies in inadequate observations and modeling of the inner core. The inadequacy in observations results from two causes: 1) Much of the inner core ocean surface is obscured from conventional remote sensing instruments by intense precipitation in the eye wall and inner rain bands. 2) The rapidly evolving (genesis and intensification) stages of the TC life cycle are poorly sampled in time by conventional polar-orbiting, wide-swath surface wind imagers. CYGNSS is specifically designed to address these two limitations by combining the all-weather performance of GNSS bistatic ocean surface scatterometry with the sampling properties of a constellation of Satellites.
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avionics of the cyclone global navigation Satellite System cygnss microsat constellation
IEEE Aerospace Conference, 2013Co-Authors: John Dickinson, C S Ruf, Jennifer L Alvarez, Randall Rose, B WallsAbstract:The Cyclone Global Navigation Satellite System (CYGNSS), which was recently selected as the Earth Venture-2 investigation by NASA's Earth Science System Pathfinder (ESSP) Program, measures the ocean surface wind field with unprecedented temporal resolution and spatial coverage, under all precipitating conditions, and over the full dynamic range of wind speeds experienced in a tropical cyclone (TC). The CYGNSS flight segment consists of 8 microSatellite-class observatories, which represent SwRI's first spacecraft bus design, installed on a Deployment Module for launch. They are identical in design but provide their own individual contribution to the CYGNSS science data set. SubSystems include the Attitude Determination and Control System (ADCS), the Communication and Data SubSystem (CDS), the Electrical Power Supply (EPS), and the Structure, Mechanisms, and Thermal SubSystem (SMT). This paper will present an overview of the mission and the avionics, including the ADCS, CDS, and EPS, in detail. Specifically, we will detail how off-the-shelf components can be utilized to do ADCS and will highlight how SwRI's existing avionics solutions will be adapted to meet the requirements and cost constraints of microsat applications. Avionics electronics provided by SwRI include a command and data handling computer, a transceiver radio, a low voltage power supply (LVPS), and a peak power tracker (PPT).
Anthony R Conn - One of the best experts on this subject based on the ideXlab platform.
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the three dimensional structure of the m31 Satellite System strong evidence for an inhomogeneous distribution of Satellites
The Astrophysical Journal, 2013Co-Authors: Anthony R Conn, Geraint F Lewis, Rodrigo A Ibata, Quentin A Parker, D B Zucker, Alan W Mcconnachie, Nicolas F MartinAbstract:We undertake an investigation into the spatial structure of the M31 Satellite System utilizing the distance distributions presented in a previous publication. These distances make use of the unique combination of depth and spatial coverage of the Pan-Andromeda Archaeological Survey to provide a large, homogeneous sample consisting of 27 of M31's Satellites, as well as M31 itself. We find that the Satellite distribution, when viewed as a whole, is no more planar than one would expect from a random distribution of equal size. A disk consisting of 15 of the Satellites is however found to be highly significant, and strikingly thin, with an rms thickness of just kpc. This disk is oriented approximately edge-on with respect to the Milky Way and almost perpendicular to the Milky Way disk. It is also roughly orthogonal to the disk-like structure regularly reported for the Milky Way Satellite System and in close alignment with M31's Giant Stellar Stream. A similar analysis of the asymmetry of the M31 Satellite distribution finds that it is also significantly larger than one would expect from a random distribution. In particular, it is remarkable that 20 of the 27 Satellites most likely lie on the Milky Way side of the galaxy, with the asymmetry being most pronounced within the Satellite subset forming the aforementioned disk. This lopsidedness is all the more intriguing in light of the apparent orthogonality observed between the Satellite disk structures of the Milky Way and M31.
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the three dimensional structure of the m31 Satellite System strong evidence for an inhomogeneous distribution of Satellites
arXiv: Cosmology and Nongalactic Astrophysics, 2013Co-Authors: Anthony R Conn, Geraint F Lewis, Rodrigo A Ibata, Quentin A Parker, D B Zucker, Alan W Mcconnachie, Nicolas F MartinAbstract:We undertake an investigation into the spatial structure of the M31 Satellite System utilizing the distance distributions presented in a previous publication. These distances make use of the unique combination of depth and spatial coverage of the Pan-Andromeda Archaeological Survey (PAndAS) to provide a large, homogeneous sample consisting of 27 of M31's Satellites, as well as M31 itself. We find that the Satellite distribution, when viewed as a whole, is no more planar than one would expect from a random distribution of equal size. A disk consisting of 15 of the Satellites is however found to be highly significant, and strikingly thin, with a root-mean-square thickness of just $12.34^{+0.75}_{-0.43}$ kpc. This disk is oriented approximately edge on with respect to the Milky Way and almost perpendicular to the Milky Way disk. It is also roughly orthogonal to the disk like structure regularly reported for the Milky Way Satellite System and in close alignment with M31's Giant Stellar Stream. A similar analysis of the asymmetry of the M31 Satellite distribution finds that it is also significantly larger than one would expect from a random distribution. In particular, it is remarkable that 20 of the 27 Satellites most likely lie on the Milky Way side of the galaxy, with the asymmetry being most pronounced within the Satellite subset forming the aforementioned disk. This lopsidedness is all the more intriguing in light of the apparent orthogonality observed between the Satellite disk structures of the Milky Way and M31.
Xuerui Wu - One of the best experts on this subject based on the ideXlab platform.
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sea level change from beidou navigation Satellite System reflectometry bds r first results and evaluation
Global and Planetary Change, 2017Co-Authors: Xiaodong Qian, Xuerui WuAbstract:Abstract Sea level changes affect human living environments, particularly ocean coasts. The tide gauges (TG) can measure sea level change, while it is the relative variations with respect to the land. Recently, GPS-Reflectometry (GPS-R) has been demonstrated to measure sea level change as an altimetry. With the rapid development of China's BeiDou Navigation Satellite System (BDS), it may provide a new possible opportunity to monitor sea level changes with three frequencies (L2, L6 and L7). In this paper, BDS-Reflectometry (BDS-R) is the first time used to estimate the sea level changes based on Signal-to-Noise Ratio (SNR) data and triple-frequency phase and code combinations, which are compared to tide gauge observations. Results show that sea level changes from BDS SNR and phase combination have a good agreement with correlation coefficients of 0.83–0.91 and RMSEs of less than 0.6 m, while BDS code combination is not as good as others. Furthermore, a new negative linear model between phase and code peak frequencies and tide gauge observations is further obtained and analyzed, which improves the results from three-frequency phase and code combinations with the RMSE of about 10 cm and 18 cm.
Nicolas F Martin - One of the best experts on this subject based on the ideXlab platform.
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the three dimensional structure of the m31 Satellite System strong evidence for an inhomogeneous distribution of Satellites
The Astrophysical Journal, 2013Co-Authors: Anthony R Conn, Geraint F Lewis, Rodrigo A Ibata, Quentin A Parker, D B Zucker, Alan W Mcconnachie, Nicolas F MartinAbstract:We undertake an investigation into the spatial structure of the M31 Satellite System utilizing the distance distributions presented in a previous publication. These distances make use of the unique combination of depth and spatial coverage of the Pan-Andromeda Archaeological Survey to provide a large, homogeneous sample consisting of 27 of M31's Satellites, as well as M31 itself. We find that the Satellite distribution, when viewed as a whole, is no more planar than one would expect from a random distribution of equal size. A disk consisting of 15 of the Satellites is however found to be highly significant, and strikingly thin, with an rms thickness of just kpc. This disk is oriented approximately edge-on with respect to the Milky Way and almost perpendicular to the Milky Way disk. It is also roughly orthogonal to the disk-like structure regularly reported for the Milky Way Satellite System and in close alignment with M31's Giant Stellar Stream. A similar analysis of the asymmetry of the M31 Satellite distribution finds that it is also significantly larger than one would expect from a random distribution. In particular, it is remarkable that 20 of the 27 Satellites most likely lie on the Milky Way side of the galaxy, with the asymmetry being most pronounced within the Satellite subset forming the aforementioned disk. This lopsidedness is all the more intriguing in light of the apparent orthogonality observed between the Satellite disk structures of the Milky Way and M31.
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the three dimensional structure of the m31 Satellite System strong evidence for an inhomogeneous distribution of Satellites
arXiv: Cosmology and Nongalactic Astrophysics, 2013Co-Authors: Anthony R Conn, Geraint F Lewis, Rodrigo A Ibata, Quentin A Parker, D B Zucker, Alan W Mcconnachie, Nicolas F MartinAbstract:We undertake an investigation into the spatial structure of the M31 Satellite System utilizing the distance distributions presented in a previous publication. These distances make use of the unique combination of depth and spatial coverage of the Pan-Andromeda Archaeological Survey (PAndAS) to provide a large, homogeneous sample consisting of 27 of M31's Satellites, as well as M31 itself. We find that the Satellite distribution, when viewed as a whole, is no more planar than one would expect from a random distribution of equal size. A disk consisting of 15 of the Satellites is however found to be highly significant, and strikingly thin, with a root-mean-square thickness of just $12.34^{+0.75}_{-0.43}$ kpc. This disk is oriented approximately edge on with respect to the Milky Way and almost perpendicular to the Milky Way disk. It is also roughly orthogonal to the disk like structure regularly reported for the Milky Way Satellite System and in close alignment with M31's Giant Stellar Stream. A similar analysis of the asymmetry of the M31 Satellite distribution finds that it is also significantly larger than one would expect from a random distribution. In particular, it is remarkable that 20 of the 27 Satellites most likely lie on the Milky Way side of the galaxy, with the asymmetry being most pronounced within the Satellite subset forming the aforementioned disk. This lopsidedness is all the more intriguing in light of the apparent orthogonality observed between the Satellite disk structures of the Milky Way and M31.
Xingpin Liu - One of the best experts on this subject based on the ideXlab platform.
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An Overview of the Science Performances and Calibration/Validation of Joint Polar Satellite System Operational Products
MDPI AG, 2019Co-Authors: Lihang Zhou, Murty Divakarla, Xingpin Liu, Arron Layns, Mitch GoldbergAbstract:The Suomi National Polar-orbiting Partnership (S-NPP) Satellite, launched in October 2011, initiated a series of the next-generation weather Satellites for the National Oceanic and Atmospheric Administration (NOAA) Joint Polar Satellite System (JPSS) program. The JPSS program at the Center for Satellite Applications and Research (JSTAR) leads the development of the algorithms, the calibration and validation of the products to meet the specified requirements, and long-term science performance monitoring and maintenance. All of the S-NPP products have been validated and are in successful operation. The recently launched JPSS-1 (renamed as NOAA-20) Satellite is producing high-quality data products that have been available from S-NPP, along with additional products, as a direct result of the instrument upgrades and science improvements. This paper presents an overview of the JPSS product suite, the performance metrics achieved for the S-NPP, and the utilization of the products by NOAA stakeholders and user agencies worldwide. The status of NOAA-20 science data products and ongoing calibration/validation (Cal/Val) efforts are discussed for user awareness. In addition, operational implementation statuses of JPSS enterprise (multisensor and multiplatform) science algorithms for product generation and science product reprocessing efforts for the S-NPP mission are discussed
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an overview of the joint polar Satellite System jpss science data product calibration and validation
Remote Sensing, 2016Co-Authors: Lihang Zhou, Murty Divakarla, Xingpin LiuAbstract:The Joint Polar Satellite System (JPSS) will launch its first JPSS-1 Satellite in early 2017. The JPSS-1 and follow-on Satellites will carry aboard an array of instruments including the Visible Infrared Imaging Radiometer Suite (VIIRS), the Cross-track Infrared Sounder (CrIS), the Advanced Technology Microwave Sounder (ATMS), and the Ozone Mapping and Profiler Suite (OMPS). These instruments are similar to the instruments currently operating on the Suomi National Polar-orbiting Partnership (S-NPP) Satellite. In preparation for the JPSS-1 launch, the JPSS program at the Center for Satellite Applications and Research (JSTAR) Calibration/Validation (Cal/Val) teams, have laid out the Cal/Val plans to oversee JPSS-1 science products’ algorithm development efforts, verification and characterization of these algorithms during the pre-launch period, calibration and validation of the products during post-launch, and long-term science maintenance (LTSM). In addition, the team has developed the necessary schedules, deliverables and infrastructure for routing JPSS-1 science product algorithms for operational implementation. This paper presents an overview of these efforts. In addition, this paper will provide insight into the processes of both adapting S-NPP science products for JPSS-1 and performing upgrades for enterprise solutions, and will discuss Cal/Val processes and quality assurance procedures.
