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Showing 1 to 18 of 18 for “"scatterometry"”.
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Wind Scatterometry with Improved Ambiguity Selection and Rain Modeling
Although generally accurate, the quality of SeaWinds on QuikSCAT scatterometer ocean vector winds is compromised by certain natural phenomena and retrieval algorithm limitations. This dissertation addresses three main contributers to scatterometer estimate error: poor ambiguity selection, estimate …
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Observation and Tracking of Tropical Cyclones Using Resolution Enhanced Scatterometry
The QuikSCAT scatterometer provides global daily coverage of oceanic near-surface vector winds. Recently, algorithms have been developed to enhance the spatial resolution of QuikSCAT winds from 25~km to 2.5~km posting. These ultra-high resolution winds are used, in comparison with standard L2B data …
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Accurate characterization of nanophotonic grating structures
… across grating regions. The system uses scatterometry in Littrow configuration and captures both the reflected zeroth and first order diffracted light. The second system determines the overall quality of a waveguide by measuring the resolution of the device using a Modulation Transfer …
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Hurricane Wind Retrieval Algorithm Development For An Airborne Conical Scanning Scatterometer
… obtained using active microwave remote sensing (scatterometry) techniques. With the increase in the number of severe hurricanes making landfall in the United States, there is increased emphasis on operational monitoring of hurricane winds from aircraft. This thesis presents a data processing …
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Satellite Scatterometers: Calibration Using a Ground Station and Statistical Measurement Theory
… data on a daily basis. Increased interest in scatterometry mandates improved design and calibration of these instruments. This dissertation presents new techniques for scatterometer calibration and addresses issues related to the design of future instruments and applications. First, the use of …
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Observational studies of scatterometer ocean vector winds in the presence of dynamic air-sea interactions
… modified by wind speed and direction. As scatterometry has evolved in recent decades, highly calibrated geophysical model functions have been designed to transform this received backscatter into vector winds. Because these products are used in so many applications, it is crucial to …
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An Ocean Surface Wind Vector Model Function For A Spaceborne Microwave Radiometer And Its Application
… 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 …
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Comparison study of SEASAT scatterometer and conventional wind fields
… function for ocean circulation models. Microwave scatterometry, as a means of remotely sensing surface wind information, developed in response to this requirement for a surface wind field with global coverage and improved spatial and temporal resolution. This development led to the 1978 deployment …
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Tropical oceanic mesoscale cold pools in observations and models
… winds. Since the field of view and underlying scatterometry principles of both the scatterometers were similar, ASCAT GF methodology was effectively replicated on RapidScat ocean vector winds for the two-year period to identify diurnally-resolved cold pool properties. This similarity also …
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Azimuth Modulation of the Radar Backscatter at Near-Normal Incidence
<p>Radar observations of the ocean surface are becoming increasingly important. Common applications are wind retrieval and global weather forecasting and characterization. Because of the common use of ocean radar measurements, it is important to understand the sensitivity of the backscatter to both …
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A Wind and Rain Backscatter Model Derived from AMSR and SeaWinds Data
The SeaWinds scatterometers aboard the QuikSCAT and ADEOS II satellites were originally designed to measure wind vectors over the ocean by exploiting the relationship between wind-induced surface roughening and the normalized radar backscatter cross-section. Recently, an algorithm for …
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A Methodology for the Design of Spaceborne Pencil-Beam Scatterometer Systems
<p>Spaceborne scatterometer instruments are important tools for the remote sensing of the Earth's environment. In addition to the primary goal of measuring ocean winds, data from scatterometers have proven useful in the study of a variety of land and cryopshere processes as well. Several satellites …
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Calibration of and Attitude Error Estimation for a Spaceborne Scatterometer using Measurements Over Land
<p>The NASA Scatterometer (NSCAT) was launched August 20, 1996 aboard the National Space Development Agency of Japan's Advanced Earth Observing Spacecraft (ADEOS). NSCAT's primary mission was to measure radar backscatter over the world's oceans. These measurements are used to generate estimates of …
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High Resolution Wind Retrieval for SeaWinds on QuikSCAT
<p>An algorithm has been developed that enables improved the resolution wind estimates from SeaWinds data. This thesis presents the development of three key portions of the high resolution wind retrieval algorithm: Compositing individual σ-0 measurements and Kp, Retrieved wind bias correction, and …
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An Implementation of Field-Wise Wind Retrieval for Seawinds on QuikSCAT
<p>Field-wise wind estimation (also known as model-based wind estimation) is a sophisticated technique to derive wind estimates from radar backscatter measurements. In contrast to the more traditional method known as point-wise wind retrieval, field-wise techniques estimate wind field model …
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Uncertainties in Oceanic Microwave Remote Sensing: The Radar Footprint, the Wind-Backscatter Relationship, and the Measurement Probability Density Function
<p>Oceanic microwave remote sensing provides the data necessary for the estimation of significant geophysical parameters such as the near-surface vector wind. To obtain accurate estimates, a precise understanding of the measurements is critical. This work clarifies and quantifies specific …
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A Field-Wise Retrieval Algorithm for SeaWinds
<p>In the spring of 1999 NASA will launch the scatterometer SeaWinds, beginning a 3 year mission to measure the ocean winds. SeaWinds is different from previous spaceborne scatterometers in that it employs a rotating pencil-beam antenna as opposed to fixed fan-beam antennas. The scanning beam …
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Multisensor Microwave Remote Sensing in the Cryosphere
<p>Because the earth's cryosphere influences global weather patterns and climate, the scientific community has had great interest in monitoring this important region. Microwave remote sensing has proven to be a useful tool in estimating sea and glacial ice surface characteristics with both …