View All Items

Title: AN OCEAN SURFACE WIND VECTOR MODEL FUNCTION FOR A SPACEBORNE MICROWAVE RADIOMETER AND ITS APPLICATION.
Creator: Soisuvarn, Seubson, Jones, W. Linwood, University of Central Florida
Abstract / Description: Ocean surface wind vectors over the ocean present vital information for scientists and forecasters in their attempt to understand the Earth's global weather and climate. As the demand for global wind velocity information has increased, the number of satellite missions that carry wind-measuring sensors has also increased; however, there are still not sufficient numbers of instruments in orbit today to fulfill the need for operational meteorological and scientific wind vector data. Over the...
Show moreOcean surface wind vectors over the ocean present vital information for scientists and forecasters in their attempt to understand the Earth's global weather and climate. As the demand for global wind velocity information has increased, the number of satellite missions that carry wind-measuring sensors has also increased; however, there are still not sufficient numbers of instruments in orbit today to fulfill the need for operational meteorological and scientific wind vector data. Over the last three decades operational measurements of global ocean wind speeds have been obtained from passive microwave radiometers. Also, vector ocean surface wind data were primarily obtained from several scatterometry missions that have flown since the early 1990's. However, other than SeaSat-A in 1978, there has not been combined active and passive wind measurements on the same satellite until the launch of the second Advanced Earth Observing Satellite (ADEOS-II) in 2002. This mission has provided a unique data set of coincident measurements between the SeaWinds scatterometer and the Advanced Microwave Scanning Radiometer (AMSR). AMSR observes the vertical and horizontal brightness temperature (TB) at six frequency bands between 6.9 GHz and 89.0 GHz. Although these measurements contain some wind direction information, the overlying atmospheric influence can easily obscure this signal and make wind direction retrieval from passive microwave measurements very difficult. However, at radiometer frequencies between 10 and 37 GHz, a certain linear combination of vertical and horizontal brightness temperatures causes the atmospheric dependence to be nearly cancelled and surface parameters such as wind speed, wind direction and sea surface temperature to dominate the resulting signal. This brightness temperature combination may be expressed as ATBV-TBH, where A is a constant to be determined and the TBV and TBH are the brightness temperatures for the vertical and horizontal polarization respectively. In this dissertation, an empirical relationship between the AMSR's ATBV-TBH and SeaWinds' surface wind vector retrievals was established for three microwave frequencies: 10, 18 and 37 GHz. This newly developed model function for a passive microwave radiometer could provide the basis for wind vector retrievals either separately or in combination with scatterometer measurements.
Show less
Date Issued: 2006
Identifier: CFE0001493, ucf:47088
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001493

Title: ANALYSIS OF TIME SYNCHRONIZATION ERRORS IN HIGH DATA RATE ULTRAWIDEBAND ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING DATA LINKS.
Creator: Bates, Lakesha, Jones, W. Linwood, University of Central Florida
Abstract / Description: Emerging Ultra Wideband (UWB) Orthogonal Frequency Division Multiplexing (OFDM) systems hold the promise of delivering wireless data at high speeds, exceeding hundreds of megabits per second over typical distances of 10 meters or less. The purpose of this Thesis is to estimate the timing accuracies required with such systems in order to achieve Bit Error Rates (BER) of the order of magnitude of 10-12 and thereby avoid overloading the correction of irreducible errors due to misaligned timing...
Show moreEmerging Ultra Wideband (UWB) Orthogonal Frequency Division Multiplexing (OFDM) systems hold the promise of delivering wireless data at high speeds, exceeding hundreds of megabits per second over typical distances of 10 meters or less. The purpose of this Thesis is to estimate the timing accuracies required with such systems in order to achieve Bit Error Rates (BER) of the order of magnitude of 10-12 and thereby avoid overloading the correction of irreducible errors due to misaligned timing errors to a small absolute number of bits in error in real-time relative to a data rate of hundreds of megabits per second. Our research approach involves managing bit error rates through identifying maximum timing synchronization errors. Thus, it became our research goal to determine the timing accuracies required to avoid operation of communication systems within the asymptotic region of BER flaring at low BERs in the resultant BER curves. We propose pushing physical layer bit error rates to below 10-12 before using forward error correction (FEC) codes. This way, the maximum reserve is maintained for the FEC hardware to correct for burst as well as recurring bit errors due to corrupt bits caused by other than timing synchronization errors.
Show less
Date Issued: 2004
Identifier: CFE0000197, ucf:46173
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000197

Title: VALIDATION OF QUICKSCAT RADIOMETER (QRAD) MICROWAVE BRIGHTNESS TEMPERTURE MEASURMENTS.
Creator: Hanna, Rafik, Jones, W.Linwood, University of Central Florida
Abstract / Description: After the launch of NASA's SeaWinds scatterometer in 1999, a radiometer function was implemented in the Science Ground Data Processing Systems to allow the measurement of the earth's microwave brightness temperature. This dissertation presents results of a comprehensive validation to assess the quality of QRad brightness temperature measurements using near-simultaneous ocean Tb comparisons between the SeaWinds on QuikSCAT (QRad) and WindSat polarimetric radiometer on Coriolis. WindSat...
Show moreAfter the launch of NASA's SeaWinds scatterometer in 1999, a radiometer function was implemented in the Science Ground Data Processing Systems to allow the measurement of the earth's microwave brightness temperature. This dissertation presents results of a comprehensive validation to assess the quality of QRad brightness temperature measurements using near-simultaneous ocean Tb comparisons between the SeaWinds on QuikSCAT (QRad) and WindSat polarimetric radiometer on Coriolis. WindSat was selected because it is a well calibrated radiometer that has many suitable collocations with QuikSCAT; and it has a 10.7 GHz channel, which is close to QRad frequency of 13.4 GHz. Brightness temperature normalizations were made for WindSat before comparison to account for expected differences in Tb with QRad because of incidence angle and channel frequency differences. Brightness temperatures for nine months during 2005 and 2006 were spatially collocated for rain-free homogeneous ocean scenes (match-ups) within 1° latitude x longitude boxes and within a ± 60 minute window. To ensure high quality comparison, these collocations were quality controlled and edited to remove non-homogenous ocean scenes and/or transient environmental conditions, including rain contamination. WindSat and QRad Tb's were averaged within 1° boxes and these were used for the radiometric inter-calibration analysis on a monthly basis. Results show that QRad calibrations are stable in the mean within ± 2K over the yearly seasonal cycle.
Show less
Date Issued: 2009
Identifier: CFE0002820, ucf:48068
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002820

Title: SIMULATION OF BRIGHTNESS TEMPERATURES FOR THE MICROWAVE RADIOMETER ON THE AQUARIUS/SAC-D MISSION.
Creator: Khan, Salman, Jones, W. Linwood, University of Central Florida
Abstract / Description: Microwave radiometers are highly sensitive receivers capable of measuring low levels of natural blackbody microwave emissions. Remote sensing by satellite microwave radiometers flying on low-earth, polar orbiting, satellites can infer a variety of terrestrial and atmospheric geophysical parameters for scientific and operational applications, such as weather and climate prediction. The objective of this thesis is to provide realistic simulated ocean brightness temperatures for the 3-channel...
Show moreMicrowave radiometers are highly sensitive receivers capable of measuring low levels of natural blackbody microwave emissions. Remote sensing by satellite microwave radiometers flying on low-earth, polar orbiting, satellites can infer a variety of terrestrial and atmospheric geophysical parameters for scientific and operational applications, such as weather and climate prediction. The objective of this thesis is to provide realistic simulated ocean brightness temperatures for the 3-channel Microwave Radiometer (MWR), which will be launched in May 2010 on the joint NASA/CONAE Aquarius/SAC-D Mission. These data will be used for pre-launch geophysical retrieval algorithms development and validation testing. Analyses are performed to evaluate the proposed MWR measurement geometry and verify the requirements for spatial/temporal sampling. Finally, a preliminary study is performed for the post-launch inter-satellite radiometric calibration using the WindSat polarimetric radiometer on the Coriolis satellite.
Show less
Date Issued: 2009
Identifier: CFE0002821, ucf:48074
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002821

Title: INTER-SATELLITE MICROWAVE RADIOMETER CALIBRATION.
Creator: Hong, Liang, Jones, W. Linwood, University of Central Florida
Abstract / Description: The removal of systematic brightness temperature (Tb) biases is necessary when producing decadal passive microwave data sets for weather and climate research. It is crucial to achieve Tb measurement consistency among all satellites in a constellation as well as to maintain sustained calibration accuracy over the lifetime of each satellite sensor. In-orbit inter-satellite radiometric calibration techniques provide a long term, group-wise solution; however, since radiometers operate at...
Show moreThe removal of systematic brightness temperature (Tb) biases is necessary when producing decadal passive microwave data sets for weather and climate research. It is crucial to achieve Tb measurement consistency among all satellites in a constellation as well as to maintain sustained calibration accuracy over the lifetime of each satellite sensor. In-orbit inter-satellite radiometric calibration techniques provide a long term, group-wise solution; however, since radiometers operate at different frequencies and viewing angles, Tb normalizations are made before making intermediate comparisons of their near-simultaneous measurements. In this dissertation, a new approach is investigated to perform these normalizations from one satellite's measurements to another. It uses Taylor's series expansion around a source frequency to predict Tb of a desired frequency. The relationship between Tb's and frequencies are derived from simulations using an oceanic Radiative Transfer Model (RTM) over a wide variety of environmental conditions. The original RTM is built on oceanic radiative transfer theory. Refinements are made to the model by modifying and tuning algorithms for calculating sea surface emission, atmospheric emission and attenuations. Validations were performed with collocated WindSat measurements. This radiometric calibration approach is applied to establish an absolute brightness temperature reference using near-simultaneous pair-wise comparisons between a non-sun synchronous radiometer and two sun-synchronous polar-orbiting radiometers: the Tropical Rain Measurement Mission (TRMM) Microwave Imager (TMI), WindSat (on Coriolis) and Advanced Microwave Scanning Radiometer (AMSR) on Advanced Earth Observing System –II (ADEOSII), respectively. Collocated measurements between WindSat and TMI as well as between AMSR and TMI, within selected 10 weeks in 2003 for each pair, are collected, filtered and applied in the cross calibration. AMSR is calibrated to WindSat using TMI as a transfer standard. Accuracy prediction and error source analysis are discussed along with calibration results. This inter-satellite radiometric calibration approach provides technical support for NASA's Global Precipitation Mission which relies on a constellation of cooperative satellites with a variety of microwave radiometers to make global rainfall measurements.
Show less
Date Issued: 2008
Identifier: CFE0002003, ucf:47626
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002003

Title: RAIN RATE ALGORITHM FOR AQUARIUS/SAC-D MICROWAVE RADIOMETER.
Creator: Menzerotolo, Rosa, Jones, W. Linwood, University of Central Florida
Abstract / Description: Microwave radiometers are used to measure blackbody microwave emissions emitted by natural targets. Radiative transfer theory provides a well founded physical relationship between the atmosphere and surface geophysical parameters and the brightness temperature measured by these radiometers. The atmospheric brightness temperature is proportional to the integral of the microwave absorption of water vapor, oxygen, and liquid water between the top of the atmosphere and the surface. Inverse...
Show moreMicrowave radiometers are used to measure blackbody microwave emissions emitted by natural targets. Radiative transfer theory provides a well founded physical relationship between the atmosphere and surface geophysical parameters and the brightness temperature measured by these radiometers. The atmospheric brightness temperature is proportional to the integral of the microwave absorption of water vapor, oxygen, and liquid water between the top of the atmosphere and the surface. Inverse radiative transfer models use to retrieve the water vapor, cloud liquid and oxygen content in the atmosphere are very well known; however, the retrieval of rain rate in the atmosphere is still a challenge. This project presents a theoretical basis for the rain rate retrieval algorithm, which will be implemented in the Aquarius/SAC-D Microwave Radiometer (MWR). This algorithm was developed based on the radiative transfer model theory for a single layer atmosphere using four WindSat channels. Transmissivity due to liquid water (rain and cloud liquid water) is retrieved from the four channel brightness temperatures, and a statistical regression is performed to relate the rain rate, rain physical temperature and rain height to the liquid water transmissivities at 24 GHz and 37 GHz. Empirical validation results are presented using the WindSat radiometer observations.
Show less
Date Issued: 2011
Identifier: CFE0003571, ucf:48911
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003571

Title: DEVELOPMENT OF AN IMPROVED MICROWAVE OCEAN SURFACE EMISSIVITY RADIATIVE TRANSFER MODEL.
Creator: El-Nimri, Salem, Jones, W. Linwood, University of Central Florida
Abstract / Description: An electromagnetic model is developed for predicting the microwave blackbody emission from the ocean surface over a wide range of frequencies, incidence angles, and wind vector (speed and direction) for both horizontal and vertical polarizations. This ocean surface emissivity model is intended to be incorporated into an oceanic radiative transfer model to be used for microwave radiometric applications including geophysical retrievals over oceans. The model development is based on a collection...
Show moreAn electromagnetic model is developed for predicting the microwave blackbody emission from the ocean surface over a wide range of frequencies, incidence angles, and wind vector (speed and direction) for both horizontal and vertical polarizations. This ocean surface emissivity model is intended to be incorporated into an oceanic radiative transfer model to be used for microwave radiometric applications including geophysical retrievals over oceans. The model development is based on a collection of published ocean emissivity measurements obtained from satellites, aircraft, field experiments, and laboratory measurements. This dissertation presents the details of methods used in the ocean surface emissivity model development and comparisons with current emissivity models and aircraft radiometric measurements in hurricanes. Especially, this empirically derived ocean emissivity model relates changes in vertical and horizontal polarized ocean microwave brightness temperature measurements over a wide range of observation frequencies and incidence angles to physical roughness changes in the ocean surface, which are the result of the air/sea interaction with surface winds. Of primary importance are the Stepped Frequency Microwave Radiometer (SFMR) brightness temperature measurements from hurricane flights and independent measurements of surface wind speed that are used to define empirical relationships between C-band (4 Ã‚Â– 7 GHz) microwave brightness temperature and surface wind speed. By employing statistical regression techniques, we develop a physical-based ocean emissivity model with empirical coefficients that depends on geophysical parameters, such as wind speed, wind direction, sea surface temperature, and observational parameters, such as electromagnetic frequency, electromagnetic polarization, and incidence angle.
Show less
Date Issued: 2010
Identifier: CFE0003085, ucf:48323
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003085

Title: HURRICANE WIND SPEED AND RAIN RATE MEASUREMENTS USING THE AIRBORNE HURRICANE IMAGING RADIOMETER (HIRAD).
Creator: Amarin, Ruba, Jones, W. Linwood, University of Central Florida
Abstract / Description: This dissertation presents results for an end-to-end computer simulation of a new airborne microwave remote sensor, the Hurricane Imaging Radiometer, HIRAD, which will provide improved hurricane surveillance. The emphasis of this research is the retrieval of hurricane-force wind speeds in the presence of intense rain and over long atmospheric slant path lengths that are encountered across its wide swath. Brightness temperature (Tb) simulations are performed using a forward microwave radiative...
Show moreThis dissertation presents results for an end-to-end computer simulation of a new airborne microwave remote sensor, the Hurricane Imaging Radiometer, HIRAD, which will provide improved hurricane surveillance. The emphasis of this research is the retrieval of hurricane-force wind speeds in the presence of intense rain and over long atmospheric slant path lengths that are encountered across its wide swath. Brightness temperature (Tb) simulations are performed using a forward microwave radiative transfer model (RTM) that includes an ocean surface emissivity model at high wind speeds developed especially for HIRAD high incidence angle measurements and a rain model for the hurricane environment. Also included are realistic sources of errors (e.g., instrument NEDT, antenna pattern convolution of scene Tb, etc.), which are expected in airborne hurricane observations. Case studies are performed using 3D environmental parameters produced by numerical hurricane models for actual hurricanes. These provide realistic Ã‚Â"nature runsÃ‚Â" of rain, water vapor, clouds and surface winds from which simulated HIRAD TbÃ‚Â's are derived for various flight tracks from a high altitude aircraft. Using these simulated HIRAD measurements, Monte Carlo retrievals of wind speed and rain rate are performed using available databases of sea surface temperatures and climatological hurricane atmospheric parameters (excluding rain) as a priori information. Examples of retrieved hurricane wind speed and rain rate images are presented, and comparisons of the retrieved parameters with the numerical model data are made. Statistical results are presented over a broad range of wind and rain conditions and as a function of path length over the full swath.
Show less
Date Issued: 2010
Identifier: CFE0003082, ucf:48330
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003082

Title: AN IMPROVED OCEAN VECTOR WINDS RETRIEVAL APPROACH USING C- AND KU-BAND SCATTEROMETER AND MULTI-FREQUENCY MICROWAVE RADIOMETER MEASUREMENTS.
Creator: Alsweiss, Suleiman, Jones, W. Linwood, University of Central Florida
Abstract / Description: This dissertation will specifically address the issue of improving the quality of satellite scatterometer retrieved ocean surface vector winds (OVW), especially in the presence of strong rain associated with tropical cyclones. A novel active/passive OVW retrieval algorithm is developed that corrects Ku-band scatterometer measurements for rain effects and then uses them to retrieve accurate OVW. The rain correction procedure makes use of independent information available from collocated multi...
Show moreThis dissertation will specifically address the issue of improving the quality of satellite scatterometer retrieved ocean surface vector winds (OVW), especially in the presence of strong rain associated with tropical cyclones. A novel active/passive OVW retrieval algorithm is developed that corrects Ku-band scatterometer measurements for rain effects and then uses them to retrieve accurate OVW. The rain correction procedure makes use of independent information available from collocated multi-frequency passive microwave observations provided by a companion sensor and also from simultaneous C-band scatterometer measurements. The synergy of these active and passive measurements enables improved correction for rain effects, which enhances the utility of Ku-band scatterometer measurements in extreme wind events. The OVW retrieval algorithm is based on the next generation instrument conceptual design for future US scatterometers, i.e. the Dual Frequency Scatterometer (DFS) developed by NASA's Jet Propulsion Laboratory. Under this dissertation research, an end-to-end computer simulation was developed to evaluate the performance of this active/passive technique for retrieving hurricane force winds in the presence of intense rain. High-resolution hurricane wind and precipitation fields were simulated for several scenes of Hurricane Isabel in 2003 using the Weather Research and Forecasting (WRF) Model. Using these numerical weather model environmental fields, active/passive measurements were simulated for instruments proposed for the Global Change Observation Mission- Water Cycle (GCOM-W2) satellite series planned by the Japanese Aerospace Exploration Agency. Further, the quality of the simulation was evaluated using actual hurricane measurements from the Advanced Microwave Scanning Radiometer and SeaWinds scatterometer onboard the Advanced Earth Observing Satellite-II (ADEOS-II). The analysis of these satellite data provided confidence in the capability of the simulation to generate realistic active/passive measurements at the top of the atmosphere. Results are very encouraging, and they show that the new algorithm can retrieve accurate ocean surface wind speeds in realistic hurricane conditions using the rain corrected Ku-band scatterometer measurements. They demonstrate the potential to improve wind measurements in extreme wind events for future wind scatterometry missions such as the proposed GCOM-W2.
Show less
Date Issued: 2011
Identifier: CFE0003757, ucf:48774
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003757

Title: Brightness Temperature Calibration of SAC-D/Aquarius Microwave Radiometer (MWR).
Creator: Biswas, Sayak, Jones, W, Georgiopoulos, Michael, Wahid, Parveen, Wilheit, Thomas, University of Central Florida
Abstract / Description: The Aquarius/SAC-D joint international science mission, between the NationalAeronautics and Space Administration (NASA) of United States and the Argentine Space Agency (Comision Nacional de Actividades Espaciales, CONAE), was launched on a polar-orbiting satellite on June 10, 2011. This mission of discovery will provide measurements of the global sea surface salinity, which contributes to understanding climatic changes in the global water cycle and how these variations inuence the general...
Show moreThe Aquarius/SAC-D joint international science mission, between the NationalAeronautics and Space Administration (NASA) of United States and the Argentine Space Agency (Comision Nacional de Actividades Espaciales, CONAE), was launched on a polar-orbiting satellite on June 10, 2011. This mission of discovery will provide measurements of the global sea surface salinity, which contributes to understanding climatic changes in the global water cycle and how these variations inuence the general ocean circulation. The Microwave Radiometer (MWR), a three channel Dicke radiometer operating at 23.8 GHz H-Pol and 36.5 GHz V-(&) H-Pol provided by CONAE, will complement Aquarius (NASA's L-band radiometer/scatterometer) by providing simultaneous spatially collocated environmental measurements such as water vapor, cloud liquid water, surface wind speed, rain rate and sea ice concentration.This dissertation focuses on the overall radiometric calibration of MWR instrument.Which means establishing a transfer function that relates the instrument output to the antenna brightness temperature (Tb). To achieve this goal, the dissertation describes a microwave radiative transfer model of the instrument and validates it using the laboratory and thermal-vacuum test data. This involves estimation of the losses and physical temperature profile in the path from the receiver to each antenna feed-horn for all the receivers. As the pre-launch laboratory tests can only provide a simulated environment which is very different from the operational environment in space, an on-orbit calibration of the instrument is very important. Inter-satellite radiometric cross-calibration of MWR using the Naval Research Laboratory's multi-frequency polarimetric microwave radiometer, WindSat, on board the Coriolis satellite is also an important part of this dissertation. Cross-calibration between two different satellite instruments require normalization of Tb's to account for the frequency and incidence angle dierence between the instruments. Also inter-satellite calibration helps to determine accurate antenna pattern correction coefficients and other small instrument biases.
Show less
Date Issued: 2012
Identifier: CFE0004200, ucf:49033
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004200

Title: A Microwave Radiometer Roughness Correction Algorithm For Sea Surface Salinity Retrieval.
Creator: Hejazin, Yazan, Jones, W, Mikhael, Wasfy, Wei, Lei, University of Central Florida
Abstract / Description: The Aquarius/SAC-D is an Earth Science remote sensing satellite mission to measure global Sea Surface Salinity (SSS) that is sponsored by the NASA and the Argentine Space Agency (CONAE). The prime remote sensor is the Aquarius (AQ) L-band radiometer/scatterometer, which measures the L-band emitted blackbody radiation (brightness temperature) from the ocean. The brightness temperature at L-band is proportional to the ocean salinity as well as a number of physical parameters including ocean...
Show moreThe Aquarius/SAC-D is an Earth Science remote sensing satellite mission to measure global Sea Surface Salinity (SSS) that is sponsored by the NASA and the Argentine Space Agency (CONAE). The prime remote sensor is the Aquarius (AQ) L-band radiometer/scatterometer, which measures the L-band emitted blackbody radiation (brightness temperature) from the ocean. The brightness temperature at L-band is proportional to the ocean salinity as well as a number of physical parameters including ocean surface wind speed. The salinity retrieval algorithm make corrections for all other parameters before retrieving salinity, and the greatest of these is the increased brightness temperature due to roughness caused by surface wind speed. This thesis presents an independent approach for the AQ roughness correction, which is derived using simultaneous measurements from the CONAE Microwave Radiometer (MWR). When the wind blows over the ocean's surface, the brightness temperature is increased because of the ocean wave surface roughness. The MWR provides a semi-empirical approach by measuring the excess ocean emissivity at 36.5 GHz and then applying radiative transfer theory (improved ocean surface emissivity model) to translate this to the AQ 1.4 GHz frequency (L-band). The theoretical basis of the MWR algorithm is described and empirical results are presented that demonstrate the effectiveness in reducing the salinity measurement error due to surface roughness.
Show less
Date Issued: 2012
Identifier: CFE0004212, ucf:49007
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004212

Title: Forecasting Volcanic Activity Using An Event Tree Analysis System and Logistic Regression.
Creator: Junek, William, Jones, W, Simaan, Marwan, Foroosh, Hassan, Woods, Mark, University of Central Florida
Abstract / Description: Forecasts of short term volcanic activity are generated using an event tree process that is driven by a set of empirical statistical models derived through logistic regression. Each of the logistic models are constructed from a sparse and geographically diverse dataset that was assembled from a collection of historic volcanic unrest episodes. The dataset consists of monitoring measurements (e.g. seismic), source modeling results, and historic eruption information. Incorporating this data into...
Show moreForecasts of short term volcanic activity are generated using an event tree process that is driven by a set of empirical statistical models derived through logistic regression. Each of the logistic models are constructed from a sparse and geographically diverse dataset that was assembled from a collection of historic volcanic unrest episodes. The dataset consists of monitoring measurements (e.g. seismic), source modeling results, and historic eruption information. Incorporating this data into a single set of models provides a simple mechanism for simultaneously accounting for the geophysical changes occurring within the volcano and the historic behavior of analog volcanoes. A bootstrapping analysis of the training dataset allowed for the estimation of robust logistic model coefficients. Probabilities generated from the logistic models increase with positive modeling results, escalating seismicity, and high eruption frequency. The cross validation process produced a series of receiver operating characteristic (ROC) curves with areas ranging between 0.78 - 0.81, which indicate the algorithm has good predictive capabilities. In addition, ROC curves also allowed for the determination of a false positive rate and optimum detection threshold for each stage of the algorithm. The results demonstrate the logistic models are highly transportable and can compete with, and in some cases outperform, non-transportable empirical models trained with site specific information. The incorporation of source modeling results into the event tree's decision making process has begun the transition of volcano monitoring applications from simple mechanized pattern recognition algorithms to a physical model based forecasting system.
Show less
Date Issued: 2012
Identifier: CFE0004253, ucf:49517
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004253

Title: Engineering Evaluation of Multi-beam Satellite Antenna Boresight Pointing using Land/Water Crossings.
Creator: May, Catherine, Jones, W, Mikhael, Wasfy, Wahid, Parveen, University of Central Florida
Abstract / Description: The Microwave Radiometer (MWR) on the Aquarius/SAC-D mission measures microwave radiation from earth and intervening atmosphere in terms of brightness temperature (Tb). It takes measurements in a push-broom fashion at K (23.8GHz) and Ka (36.5 GHz) band frequencies using two separate antenna systems, each producing eight antenna beams. Pre-launch knowledge of the alignment of these beams with respect to the space-craft is used to geolocate the antenna footprints on ground. As a part of MWR's...
Show moreThe Microwave Radiometer (MWR) on the Aquarius/SAC-D mission measures microwave radiation from earth and intervening atmosphere in terms of brightness temperature (Tb). It takes measurements in a push-broom fashion at K (23.8GHz) and Ka (36.5 GHz) band frequencies using two separate antenna systems, each producing eight antenna beams. Pre-launch knowledge of the alignment of these beams with respect to the space-craft is used to geolocate the antenna footprints on ground. As a part of MWR's on-orbit engineering check-out, the verification of MWR's pointing accuracy is discussed here. The technique used to assess MWR's pointing involved comparing the radiometer image of land with high-resolution maps. When the beam's instantaneous field of view (IFOV) passes over a land water boundary, the brightness temperature changes from a radiometrically hot land scene to a radiometrically cold ocean scene. This (")step-function(") change in brightness temperature provides a very sensitive way to characterize the mispointing error of the MWR sensor antenna footprints. This thesis describes the algorithm used for the MWR geolocation calibration. MWR sensor observed boundaries are determined by the absolute maximum Tb slope location. A system of linear equations is produced for each sensor observed land/water crossing to determine the true intersection of the MWR track with the coastline. The observed and expected boundary locations are compared by means of an error distance. Results, presented for all eight beams of the three MWR channels, show that the mispointing error (standard deviations) are overall less than 15 km from the true coastline.
Show less
Date Issued: 2012
Identifier: CFE0004245, ucf:49523
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004245

Title: Synchronous Communication System for SAW Sensors Interrogation.
Creator: Troshin, Maxim, Malocha, Donald, Jones, W, Gong, Xun, University of Central Florida
Abstract / Description: During past two decades a variety of SAW based wireless sensors were invented and research is still in progress. As different frequencies, varied bandwidths, coding techniques and constantly changing post processing algorithms are being implemented, there is a constant need for a universal and adjustable synchronous communication system able to interrogate new generations of SAW sensors. This thesis presents the design of a multiple FPGA based communication system with an operational...
Show moreDuring past two decades a variety of SAW based wireless sensors were invented and research is still in progress. As different frequencies, varied bandwidths, coding techniques and constantly changing post processing algorithms are being implemented, there is a constant need for a universal and adjustable synchronous communication system able to interrogate new generations of SAW sensors. This thesis presents the design of a multiple FPGA based communication system with an operational frequency range of 450MHz-2.2GHz capable of producing user programmed modulated signal. The synchronous receiver is designed to have interchangeable chip, replacement of which would allow adjustment of the receiver's bandwidth. Within this paper the performance of the system is only evaluated at 915MHz centered 20MHz bandwidth region. An OFC temperature sensor was interrogated. Post-processing algorithms, measurement results, and proposals for the future use of the system are presented. Detailed overview of the structure and performance of every functional block along with design considerations are analyzed. Previously designed Matlab based software was adapted for post processing of the received signal. New software with simplified GUI was designed for programming of the desired signal.
Show less
Date Issued: 2012
Identifier: CFE0004270, ucf:49543
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004270

Title: Microwave Radiometer (MWR) Evaluation of Multi-Beam Satellite Antenna Boresight Pointing Using Land-Water Crossings, for the Aquarius/SAC-D Mission.
Creator: Clymer, Bradley, Jones, W Linwood, Mikhael, Wasfy, Flitsiyan, Elena, University of Central Florida
Abstract / Description: This research concerns the CONAE Microwave Radiometer (MWR), on board the Aquarius/SAC-D platform. MWR's main purpose is to provide measurements that are simultaneous and spatially collocated with those of NASA's Aquarius radiometer/scatterometer. For this reason, knowledge of the MWR antenna beam footprint geolocation is crucial to mission success.In particular, this thesis addresses an on-orbit validation of the MWR antenna beam pointing, using calculated MWR instantaneous field of view ...
Show moreThis research concerns the CONAE Microwave Radiometer (MWR), on board the Aquarius/SAC-D platform. MWR's main purpose is to provide measurements that are simultaneous and spatially collocated with those of NASA's Aquarius radiometer/scatterometer. For this reason, knowledge of the MWR antenna beam footprint geolocation is crucial to mission success.In particular, this thesis addresses an on-orbit validation of the MWR antenna beam pointing, using calculated MWR instantaneous field of view (IFOV) centers, provided in the CONAE L-1B science data product. This procedure compares L-1B MWR IFOV centers at land/water crossings against high-resolution coastline maps. MWR IFOV locations versus time are computed from knowledge of the satellite's instantaneous location relative to an earth-centric coordinate system (provided by on-board GPS receivers), and a priori measurements of antenna gain patterns and mounting geometry.Previous conical scanning microwave radiometer missions (e.g., SSM/I) have utilized observation of rapid change in brightness temperatures (T_B) to estimate the location of land/water boundaries, and subsequently to determine the antenna beam-pointing accuracy. In this thesis, results of an algorithm to quantify the geolocation error of MWR beam center are presented, based upon two-dimensional convolution between each beam's gain pattern and land-water transition. The analysis procedures have been applied to on-orbit datasets that represent land-water boundaries bearing specific desirable criteria, which are also detailed herein. The goal of this research is to gain a better understanding of satellite radiometer beam-pointing error and thereby to improve the geolocation accuracy for MWR science data products.
Show less
Date Issued: 2015
Identifier: CFE0005591, ucf:50269
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005591

Title: DEVELOPMENT OF AN OCEANIC RAIN ACCUMULATION PRODUCT IN SUPPORT OF SEA SURFACE SALINITY MEASUREMENTS FROM AQUARIUS/SAC-D.
Creator: Aslebagh, Shadi, Jones, W, Wahid, Parveen, Junek, William, University of Central Florida
Abstract / Description: Aquarius/SAC-D is a joint mission by National Aeronautics and Space Administration (NASA) and the Comision Nacional de Actividades Espaciales (CONAE), Argentine Space Agency. The satellite was launched in June 2011 and the prime remote sensing instrument is also named Aquarius (AQ). The main objective of this science program is to provide Sea Surface Salinity (SSS) maps of the global oceans every 7 days for understanding the Earth's hydrologic cycle and for assessing long-term global climate...
Show moreAquarius/SAC-D is a joint mission by National Aeronautics and Space Administration (NASA) and the Comision Nacional de Actividades Espaciales (CONAE), Argentine Space Agency. The satellite was launched in June 2011 and the prime remote sensing instrument is also named Aquarius (AQ). The main objective of this science program is to provide Sea Surface Salinity (SSS) maps of the global oceans every 7 days for understanding the Earth's hydrologic cycle and for assessing long-term global climate change.The Aquarius instrument was built jointly by NASA's Goddard Space Flight Center and the Jet Propulsion Laboratory. It is an active/passive L-band remote sensor that measures ocean brightness temperature (Tb) and radar backscatter, and these quantities are used to infer sea surface salinity.Other environmental parameters (e.g., sea surface temperature, wind speed and rain) also affect the microwave emitted radiance or brightness temperature. The SSS geophysical retrieval algorithm considers all these environmental parameters and makes the Tb corrections before retrieving SSS. Instantaneous rainfall can cause increase roughness that raises the ocean surface Tb. Further short term rain accumulation can produce a fresh water lens that floats on the ocean surface and dilutes the surface salinity.This thesis presents results of a study to develop an oceanic rain accumulation (RA) product that may be valuable to remote sensing engineers and algorithm developers and Aquarius scientists. The use of this RA product, along with in situ ocean salinity measurements from buoys, may be used to mitigate the effects of rain on the SSS retrieval.
Show less
Date Issued: 2013
Identifier: CFE0004647, ucf:49906
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004647

Title: An Emissive Antenna Correction for The Tropical Rainfall Measuring Mission Microwave Imager (TMI).
Creator: Alquaied, Faisal, Jones, W Linwood, Mikhael, Wasfy, Wei, Lei, Zec, Josko, Wilheit, Thomas, University of Central Florida
Abstract / Description: This dissertation deals with the radiometric calibration of a satellite microwave radiometer known as the TRMM Microwave Imager (TMI), which operated on NASA's Tropical Rainfall Measuring Mission (TRMM). This multi-frequency, conical-scanning, passive microwave, remote sensor measures the earth's blackbody emissions (brightness temperature, Tb) from a low earth orbit and covers the tropics ((&)#177;35(&)deg; latitude). The original scientific objective for TRMM's 3-year mission was to measure...
Show moreThis dissertation deals with the radiometric calibration of a satellite microwave radiometer known as the TRMM Microwave Imager (TMI), which operated on NASA's Tropical Rainfall Measuring Mission (TRMM). This multi-frequency, conical-scanning, passive microwave, remote sensor measures the earth's blackbody emissions (brightness temperature, Tb) from a low earth orbit and covers the tropics ((&)#177;35(&)deg; latitude). The original scientific objective for TRMM's 3-year mission was to measure the statistics of rainfall in the tropics. However, the mission was quite successful, and TRMM was extended for greater than 17 years to provide a long-term satellite rain measurements, which has contributed significantly to the study of global climate change.A significant part of the extended TRMM mission was the establishment of a constellation of satellite radiometer that provide frequent global rainfall measurements that enable severe storm warnings for operational hazard forecast by the international weather community. TRMM played a key role by serving as the radiometric calibration standard for the TRMM constellation microwave radiometers.The objective of this dissertation is to improve the radiometric calibration of TMI and to provide to NASA a new robust, physics-based algorithm for the legacy data processing of the TRMM brightness temperature data product, which will be called TMI 1B11 V8. Moreover, the results of this new procedure have been validated using the double difference techniques with the Global Precipitation Mission Microwave Imager (GMI), which is the replacement satellite mission to TRMM.
Show less
Date Issued: 2017
Identifier: CFE0006711, ucf:51900
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006711

Title: Method for Real-Time Signal Selection for Passive Coherent Location Systems.
Creator: Johnson, Nicholas, Jones, W Linwood, Gong, Xun, Mikhael, Wasfy, Rockway, John, Lichtenberg, Christopher, University of Central Florida
Abstract / Description: Passive coherent location (PCL) systems use signals of opportunity to perform traditional radar detection, targeting, and tracking functions. Traditionally these signals include FM radio, digital TV, GSM, and GPS because of their availability in most urban environments. A benefit of having an abundance of signals is the ability to choose which of those best meet the desired system intentions. For example, one may want to choose a digital TV signal over an FM radio signal due to its range...
Show morePassive coherent location (PCL) systems use signals of opportunity to perform traditional radar detection, targeting, and tracking functions. Traditionally these signals include FM radio, digital TV, GSM, and GPS because of their availability in most urban environments. A benefit of having an abundance of signals is the ability to choose which of those best meet the desired system intentions. For example, one may want to choose a digital TV signal over an FM radio signal due to its range resolution characteristics. This work presents a novel algorithm for characterizing commercial signals for use in a PCL system. By analyzing each signal's ambiguity function in terms of amplitude, transmitter geometry, range and Doppler resolution, and sidelobe levels, a comparative evaluation can be made to decide which signals are best suited for an intended radar function. In addition, this research shows that multiple signals can be combined in the detection process to increase the probability of detection over that of a single signal. Finally, this research investigates the geometric considerations for PCL systems in terms of bistatic radar geometry. The results show zones of linear and non-linear relationships between time delay, range, and Doppler frequency.
Show less
Date Issued: 2017
Identifier: CFE0007123, ucf:51964
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007123

Title: Customizable Antenna Array Using Reconfigurable Antenna Elements.
Creator: Shirazi, Mahmoud, Gong, Xun, Wahid, Parveen, Jones, W Linwood, Abdolvand, Reza, Kuebler, Stephen, University of Central Florida
Abstract / Description: A shared-aperture reconfigurable slot-ring antenna array switching between different frequency bands and polarizations is presented for phased array applications. PIN diode switches are incorporated into the slots of the antenna to change the state of the reconfigurable slot-ring antenna array. Each frequency band has its own feeding lines which allows for the use of high-performance narrow-band transmit/receive (T/R) modules instead of ultra wideband (UWB) T/R modules. Furthermore, the...
Show moreA shared-aperture reconfigurable slot-ring antenna array switching between different frequency bands and polarizations is presented for phased array applications. PIN diode switches are incorporated into the slots of the antenna to change the state of the reconfigurable slot-ring antenna array. Each frequency band has its own feeding lines which allows for the use of high-performance narrow-band transmit/receive (T/R) modules instead of ultra wideband (UWB) T/R modules. Furthermore, the spacing between the elements in each frequency band is less than half free-space wavelength (?0) over the frequency band of operation which enables grating-lobe-free beam scanning. This is the first shared-aperture reconfigurable dual-polarized antenna with separate feeding for each band which is scalable to a larger array with element spacing of less than 0.5?0 in all frequency bands of operation.First, a switchable-band reconfigurable antenna array switching between L and C bands is presented. This antenna operates at 1.76/5.71 GHz with a fractional bandwidth (FBW) of 8.6%/11.5%, realized gain of 0.1/4.2 dBi and radiation efficiency of 66.6%/80.7% in the L-/C- band operating states, respectively. Second, a wideband version of the reconfigurable antenna element using fractal geometries is presented. This dual-polarized antenna element is switching between S and C bands with wide bandwidth in each operating state. In the S-/C-band operating state, this antenna shows 69.1%/58.3% FBW with a maximum realized gain of 2.4/3.1 dBi. Third, the wideband antenna element is extended to an antenna array. The reconfigurable dual-polarized antenna array with vertical coaxial feeding switches between S- and C-band states with full-band coverage. A 2(&)#215;2 S-band antenna array can be reconfigured to a 4(&)#215;4 C-band antenna array by activating/deactivating PIN diode switches. This antenna array shows 64.3%/66.7% FBW with 8.4/14.3 dBi maximum realized gain in the S-/C-band operating states, respectively. Finally, a reconfigurable antenna element covering three adjacent frequency bands is presented. The FBW of this tri-band antenna element is 75%/63%/26% in the S/C/X band state.
Show less
Date Issued: 2018
Identifier: CFE0007373, ucf:52092
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007373

Title: The Contribution of Adult Attachment Style on the Experience of Posttraumatic Growth Among Adult Survivors of Childhood Sexual Abuse.
Creator: Nelson, Kristina, Hagedorn, W. Bryce, Lambie, Glenn, Jones, Dayle, Xu, Lihua, Foster, Jennifer, University of Central Florida
Abstract / Description: The purpose of this research study was to investigate the directional relationship between adults' attachment styles and perceived impact of childhood sexual abuse (CSA) with their experience of posttraumatic growth. This investigation tested the theoretical model that adults' (N = 292) attachment styles as measured by the Experiences in Close Relationships-Short Form ([ECR-S] Wei et al., 2007) and impact of childhood sexual abuse as measured by the Impact of Event Scale-revised ([IES-R]...
Show moreThe purpose of this research study was to investigate the directional relationship between adults' attachment styles and perceived impact of childhood sexual abuse (CSA) with their experience of posttraumatic growth. This investigation tested the theoretical model that adults' (N = 292) attachment styles as measured by the Experiences in Close Relationships-Short Form ([ECR-S] Wei et al., 2007) and impact of childhood sexual abuse as measured by the Impact of Event Scale-revised ([IES-R] Weiss (&) Marmar, 1997) contributed to their experience of posttraumatic growth as measured by the Posttraumatic Growth Inventory ([PTGI] Tedeschi (&) Calhoun, 1996). Specifically, this investigation tested the hypothesized directional relationship that adult survivors of CSA scoring in the insecure attachment range (i.e., avoidant or anxious) with higher levels of trauma would have lower levels of posttraumatic growth. In addition, this investigation examined the differences in relationship between adults' attachment styles, perceived impact of CSA, and posttraumatic growth based on their reported demographic information (e.g., age, race, and gender). The results of the structural equation model (SEM) analyses identified that trauma experienced by adult survivors of CSA contributed to 39% of the variance in the attachment style (p (<) .000; standardized coefficient = .63), and the mediating effect of attachment style contributed to 8% of the variance in the presence of PTG (p (<) .05; standardized coefficient -.31), while trauma showed to have no significant influence on the presence of PTG in this sample (p = .756). Implications of the findings from the study include insight (a) for counselors to better understand the experiences of adult survivors of CSA and areas to address in treatment; (b) for counselor educators to better prepare future counselors to work with adult survivors of CSA; and (c) insight into the instrument development of the ECR-S, IES-R, and PTGI.
Show less
Date Issued: 2016
Identifier: CFE0006696, ucf:51919
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006696

Remote Sensing (6)	+ -
Calibration (5)	+ -
HIRAD (4)	+ -
WindSat (4)	+ -
Aquarius (3)	+ -

Microwave Remote Sensing (3)	+ -
SFMR (3)	+ -
TMI (3)	+ -
brightness temperature (3)	+ -
AMSR (2)	+ -
Antennas (2)	+ -
Aquarius/SAC-D (2)	+ -
Face Recognition (2)	+ -
Hurricane Observation (2)	+ -
MWR (2)	+ -
Microwave Radiometer (2)	+ -
Radiometry (2)	+ -
Reconfigurable antennas (2)	+ -
Satellite Remote Sensing (2)	+ -
TRMM (2)	+ -
radiometer (2)	+ -
remote sensing (2)	+ -
Activities of Daily Living (1)	+ -
Along-scan bias (1)	+ -
Arrays (1)	+ -
BST (1)	+ -
Beam steering (1)	+ -
C-band (1)	+ -
CMOS (1)	+ -
CONOE Microwave Radiometer (1)	+ -

University of Central Florida (38)	+ -
Jones, W Linwood (19)	+ -
Mikhael, Wasfy (17)	+ -
Wahid, Parveen (15)	+ -
Gong, Xun (9)	+ -

Jones, W (9)	+ -
Jones, W. Linwood (8)	+ -
Junek, William (5)	+ -
Wei, Lei (5)	+ -
Wilheit, Thomas (5)	+ -
Atia, George (3)	+ -
Zec, Josko (3)	+ -
Flitsiyan, Elena (2)	+ -
Georgiopoulos, Michael (2)	+ -
Hejazin, Yazan (2)	+ -
Kuebler, Stephen (2)	+ -
Piepmeier, Jeffrey (2)	+ -
Wu, Thomas (2)	+ -
Wu, Xinzhang (2)	+ -
Abdolvand, Reza (1)	+ -
Al Obaidi, Taif (1)	+ -
Alasgah, Abdusalam (1)	+ -
Aldhahab, Ahmed (1)	+ -
Alquaied, Faisal (1)	+ -
Alsweiss, Suleiman (1)	+ -
Amarin, Ruba (1)	+ -
Asher, William (1)	+ -
Aslebagh, Shadi (1)	+ -
Bates, Lakesha (1)	+ -
Biswas, Sayak (1)	+ -

Search In

Pages

Pages

Sort Results By:

Narrow results by:

Topical Subject

Collection

Type of Resource

Language

Creator

Format

Owner