Mr. Steven D. Harrah Profile

Steven D. Harrah

at NASA Langley Research Ctr

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Author

Publications (5)

Proceedings Article | 27 May 2022 Presentation + Paper

Development of polarimetric radar product and initial application for airborne HIWC detection

Yunish Shrestha, Yan Rockee Zhang, Jakob Fusselman, Greg McFarquhar, WIlliam Blake, Steven Harrah

Proceedings Volume 12108, 1210806 (2022) https://doi.org/10.1117/12.2618447

KEYWORDS: Radar, Monte Carlo methods, Reflectivity, Data modeling, Particles, Scattering, Autoregressive models, Antennas, Sensors, Polarimetry

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Proceedings Article | 12 April 2021 Presentation + Paper

Development of simulation and evaluation for high ice water content (HIWC) hazard detection using airborne radar

Yunish Shrestha, Yan (Rockee) Zhang, Greg McFarquhar, William Blake, Steven Harrah

Proceedings Volume 11742, 1174211 (2021) https://doi.org/10.1117/12.2586347

KEYWORDS: Radar, 3D modeling, Particles, Data modeling, Clouds, Standards development, Systems modeling, Space operations, Sensors, Safety

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High Ice Water Content (HIWC) is an atmospheric condition at high altitude that may lead to failure of jet engines. As a potential threat to aviation safety and space launch operation, it has received significant attentions from cross-disciplinary communities. Detecting HIWC conditions with airborne radar is essential to the safe monitoring of this type of hazard, however it has unique and significant challenges. For example, in general, small ice particles and clusters of ice particles do not register strong radar reflectivity, which is a challenge to the sensitivities and resolutions of small aperture airborne radars. Second, it is difficult to discriminate HIWC from other atmosphere conditions, such as general precipitations, and evaluate the threat level (in quantity of Ice Water Content, or IWC) with remote sensing only. In this study, we developed a novel simulation-based approach, which uses the in-situ probe collected HIWC cloud probe data during a series of flight test campaigns, as well as the microphysical particle models retrieved from these data as the basis of simulations. Then, we combine and reconcile these models with the ground-radar measurements, which leads to a three-dimensional truth gird. Using this truth field, we developed a single-cell-Monte-Carlo (SCMC) simulation implementation, which creates and generates airborne weather radar signatures and moments for each individual resolution cell. The simulation has incorporated (1) An initial framework of airborne radar system and sensor modeling, (2) Modeling of ground clutters and effect of antenna patterns. The simulation tool has significant applications in the areas of (1) Guidance of designing and development of next generation airborne hazard sensing and avoidance radars. (2) Support industry standard making and performance evaluations such as FAA, and (3) Support scientific studies on airborne radar signatures and techniques for further understanding of hazardous atmosphere conditions for aviation.

Proceedings Article | 18 October 2019 Presentation

Potential satellite mission on atmospheric dynamics for severe weather forecasts (Conference Presentation)

Bing Lin, Qilong Min, Steven Harrah, Yongxiang Hu, Roland Lawrence

Proceedings Volume 11151, 111510J (2019) https://doi.org/10.1117/12.2531710

KEYWORDS: Satellites, Meteorological satellites, Remote sensing, Radar, Oxygen, Absorption, Sensing systems, Environmental sensing, Sensors, Atmospheric sensing

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Surface air pressure is the most important atmospheric variable for atmospheric dynamics. It is regularly measured by in-situ meteorological sensors, and there are no operational capabilities that could remotely sense the pressure over the globe. The poor spatiotemporal coverage of this dynamically crucial variable is a significant observational gap in weather predictions. To improve forecasts of severe weather conditions, especially the intensity and track of tropical storms, large spatial coverage and frequent sampling of surface barometry are critically needed for numerical weather forecast models. Recent development in remote sensing techniques provides a great hope of atmospheric barometry in large spatiotemporal scales. Currently, NASA Langley Research Center tries to use the concept of Differential-absorption Barometric Radar (DiBAR) working at the 50-56 GHz O2 absorption bands to fill the observational gap. The numerical simulation shows that with this DiBAR remote sensing system, the uncertainty in instantaneous radar surface air pressure estimates can be as low as ~1 mb. Prototype instrumentation and its related laboratory, ground and airborne experiments indicate that satellite DiBAR remote sensing systems will obtain needed air pressure observations and meet or exceed the science requirements for surface air pressure fields. Observational system simulation experiments (OSSEs) for space DiBAR performance based on the existing DiBAR technology and capability show substantial improvements in tropical storm predictions, not only for the typhoon track and position but also for the typhoon intensity. Satellite DiBAR measurements will provide an unprecedented level of the prediction and knowledge on global extreme weather conditions. A space multi-frequency differential oxygen absorption radar system will fill the gap in the global observations of atmospheric air pressure, increase our knowledge in the dynamics, and significantly improve weather, especially severe weather such as typhoon and hurricane, predictions. Advanced tropical storm forecasts are expected with the studied capability. The development of the DiBAR system and associated OSSE results will be presented.

Proceedings Article | 25 May 2005 Paper

Real-time enhanced vision system

Glenn Hines, Zia-ur Rahman, Daniel Jobson, Glenn Woodell, Steven Harrah

Proceedings Volume 5802, (2005) https://doi.org/10.1117/12.603656

KEYWORDS: Digital signal processing, Cameras, Image processing, Signal processing, Short wave infrared radiation, Visibility, Image enhancement, Sensors, Long wavelength infrared, Video

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Proceedings Article | 28 August 2001 Paper

Multispectral uncooled infrared enhanced-vision system for flight test

Carlo Tiana, Richard Kerr, Steven Harrah

Proceedings Volume 4363, (2001) https://doi.org/10.1117/12.438026

KEYWORDS: Sensors, Infrared sensors, Heads up displays, Safety, Infrared radiation, Infrared imaging, Vanadium, Imaging systems, Aerodynamics, Image sensors

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