Engineering topics

Steven Harrah

Publications and source records attributed to Steven Harrah.

7 records

NASA NTRS2024

Observing System Simulation Experiments Exploring Potential Spaceborne Deployment Options for a Differential Absorption Radar Measuring Marine Surface Pressures

A new technology for remote measurements of marine surface pressure has been proposed, employing a V-band differential absorption radar and a radiometric temperature sounder to calculate the total column atmospheric mass. Observing System Simulation Experiments (OSSEs) are performed to evaluate the potential impact of Spaceborne Marine Surface Pressure (SMSP) on Numerical Weather Prediction. These experiments build on prior efforts (Privé, McLinden, et al., 2023, https://doi.org/10.16993/tellusa.3254), but with an updated version of the OSSE framework and with more sophisticated simulation of the SMSP observations and a longer experiment period. Several different instrument configurations are compared, including both scanning and non-scanning orbits. SMSP impacts are calculated for analysis quality and forecast skill, and a forecast sensitivity observation impact tool is employed to place SMSP observations in context with the global observing network. The effects of rain contamination on observation quality are explored. Different magnitudes of simulated SMSP observation error are tested in the context of data assimilation to show the range of potential behaviors. Overall, SMSP observations are found to be most beneficial in the southern hemisphere extratropics, with statistically significant forecast improvements for the first 72 hr of the forecast. A constellation of four non-scanning SMSP satellites is found to outperform a single scanning instrument with a 250 km wide swath.

N C Prive↗

NASA NTRS2022

NASA Analysis of Alternatives Study for Icing Research

In 2020, NASA’s Aeronautics Research Mission Directorate commissioned a study of the icing research area to provide a broad and comprehensive assessment of priority needs for NASA and enduring needs for the aviation community. Priority needs were those that supported four key focus areas for NASA Aeronautics—Transonic Truss-Braced Wing, Electrified Aircraft Propulsion, Small-Core Turbine Engine, and High-Rate Composite Manufacturing—as well as other priority areas, such as Advanced Air Mobility, Certification by Analysis, and Commercial Supersonic Technology. Enduring needs were the additional long-term capabilities and expertise identified by the aviation community as being critical for NASA to provide. This study is called an Analysis of Alternatives (AoA) because a large number of icing research needs were identified and analyzed to determine the highest priorities for NASA key focus areas and those that will endure into the future. This report offers a detailed description and results of the AoA study for icing research.

Aircraft Icing, Aircraft Icing, Rotorcraft Icing, ↗

NASA NTRS2021

Comparisons of Cloud In-Situ Microphysical Properties of Deep Convective Clouds to Appendix D/P using Data from the HAIC-HIWC and HIWC-RADAR I Flight Campaigns

In-situ cloud data from three international flight campaigns are compared to the Federal Aviation Administration Title 14 Code of Federal Regulations Part 33 Appendix D mixed-phase/glaciated environmental envelope, and the corresponding identical European Aviation Safety Agency CS-25 Appendix P envelope. The appendices consist of a temperature-altitude envelope, a 99th percentile total water content envelope at the 17.4 Nm distance scale, a distance factor for estimation at other distance scales, ice crystal median mass diameter, and recommended liquid water content levels in mixed-phase icing conditions. The data were collected during 54 flights out of one subtropical and two tropical locations, with 472 runs from about 17,000’ to 39,000’ in approximately 115 clouds. The campaigns provide about 29,600 Nm of in situ data in deep convection over four targeted temperature intervals: -10, -30, -40, and -50, all ± 5 C. The dataset is a modern and unique documentation of the ice crystal icing environment, and results described in this article will contribute to regulatory and industry assessment of Appendices D and P.

Ice Crystal Icing↗

NASA NTRS2020

High Ice Water Content in Tropical Cyclones during NASA/FAA Radar Flight Campaigns with Comparison to Numerical Simulations

Results from two recent flight campaigns into High Ice Water Content (HIWC) are summarized. HIWC was detected with airborne radar and measured via microphysical probes mounted on NASA’s DC-8. Results from the campaign demonstrate detectability of HIWC using airborne radar. In the cases examined, tropical storms are more proficient at producing large areas of HIWC than hurricanes. Three-dimensional, numerical simulations of tropical cyclones encountered during the campaign are also presented and are compared to measurements in order to understand conditions associated with HIWC. Within Hurricane Lane (2018), the highest ice water contents were found in regenerating thermal plumes located in the eye wall and in feeder bands. Within Tropical Storm Danny (2015), large areas of ice water content greater than 1 g m-3 were fed by broad-areas of convection occurring downwind from the center of circulation.

Aviation hazards↗

NASA NTRS2020

Airborne Weather Radar Observations & Analysis Results from the 2014/2015 HAIC Flight Campaigns

This document presents a summary of the airborne weather radar observations made during joint EU/US flight campaigns to study High Altitude Ice Crystal (HAIC) atmospheric conditions. These flight campaigns were conducted near Darwin, Australia and Cayenne, French Guiana in 2014 and 2015, respectively. A variety of analyses were conducted resulting in statistical descriptions of the radar reflectivities of HAIC encountered during storm penetrations. These results are presented along with a set of visualization tools that aided flight operations and post-flight assessments. A summary of HAIC radar reflectivities observed during these flight campaigns corroborates reports by commercial pilots during HAIC encounters.

Radar↗

NASA NTRSDate not supplied

High Ice Water Content in Tropical Cyclones During NASA/FAA Radar Flight Campaigns with Comparison to Numerical Simulations

Results from two recent flight campaigns into High Ice Water Content (HIWC) are summarized. HIWC was detected with airborne radar and measured via microphysical probes mounted on NASA’s DC-8. Results from the campaign demonstrate detectability of HIWC using airborne radar. In the cases examined, tropical storms are more proficient at producing large areas of HIWC than hurricanes. Three-dimensional, numerical simulations of tropical cyclones encountered during the campaign are also presented and are compared to measurements in order to understand conditions associated with HIWC. Within Hurricane Lane (2018), the highest ice water contents were found in regenerating thermal plumes located in the eye wall and in feeder bands. Within Tropical Storm Danny (2015), large areas of ice water content greater than 1 g/cu. m were fed by broad-areas of convection occurring downshear from the center of circulation.

Fred H. Proctor↗

NASA NTRSDate not supplied

Status of the Microwave Barometric Radar and Sounder (MBARS)

Atmospheric surface pressure and pressure profiles are essential variables in weather modeling and forecasting. Pressure gradients generate atmospheric motion and are essential to the air-sea heat exchange feedbacks within the planetary boundary layer (PBL) that lead to convective storms and heavy precipitation. Despite the importance of pressure and pressure gradients on meso-, synoptic-, and global-scale weather patterns, current technology relies almost entirely on buoy measurements over the majority of the ocean. These measurements are too sparse to capture pressure gradients of even many synoptic scale events, and leave models starved of information. NASA/Goddard Space Flight Center (GSFC), NASA/Langley Research Center (LaRC), and Tomorrow.io have begun development of the Microwave Barometric Radar and Sounder (MBARS), an airborne sensor to retrieve surface air pressure and vertical pressure profiles, especially over oceans. MBARS is a new combined active/passive microwave instrument in the O2 absorption V-band (64-70 GHz) funded by the NASA Earth Science Technology Office (ESTO) Instrument Incubator Program (IIP). This instrument consists of an innovative scanning multi-channel differential absorption radar (DAR) to provide an estimation of total atmospheric column oxygen content and thus the surface dry air pressure. MBARS also will provide hyperspectral radiometric temperature profiling to enables vertical pressure profiles using the hypsometric relationship between pressure and temperature. A co-located microwave radiometer will provide the integrated water vapor mass contribution to atmospheric pressure. This presentation will summarize the project, retrieval concept, and engineering status of the MBARS project.

Radar, Radiometer↗