Hurricane Imaging Radiometer (HIRAD) Wind Speed Retrievals and Validation Using Dropsondes

Surface wind speed retrievals have been generated and evaluated using Hurricane Imaging Radiometer (HIRAD) measurements from flights over Hurricane Joaquin, Hurricane Patricia, Hurricane Marty, and the remnants of Tropical Storm Erika, all in 2015. Procedures are described here for producing maps of brightness temperature, which are subsequently used for retrievals of surface wind speed and rain rate across a approx.50 km wide swath for each flight leg. An iterative retrieval approach has been developed to take advantage of HIRAD's measurement characteristics. Validation of the wind speed retrievals has been conducted, using 636 dropsondes released from the same WB-57 high altitude aircraft carrying HIRAD during the Tropical Cyclone Intensity (TCI) experiment. The HIRAD wind speed retrievals exhibit very small bias relative to the dropsondes, for winds tropical storm strength (17.5 m/s) or greater. HIRAD has reduced sensitivity to winds weaker than tropical storm strength, and a small positive bias (approx.2 m/s) there. Two flights with predominantly weak winds according to the dropsondes have abnormally large errors from HIRAD, and large positive biases. From the other flights, root mean square errors are 4.1 m/s (33%) for winds below tropical storm strength, 5.6 m/s (25%) for tropical storm strength winds, and 6.3 m/s (16%) for hurricane strength winds. Mean absolute errors for those categories are 3.2 m/s (25%), 4.3 m/s (19%), and 4.8 m/s (12%), with bias near zero for tropical storm and hurricane strength winds

The Proof of Concept of The Hurricane Imaging Radiometer: Hurricane Wind Speed and Rain Rate Retrievals

This dissertation presents the proof of concept for the Hurricane Imaging Radiometer (HIRAD), where remote sensing retrievals of the 2-dimensional wind and rain fields for several hurricanes are validated with independent measurements. A significant contribution of this dissertation is the development of a novel statistical calibration technique, whereby the HIRAD instrument is radiometrically calibrated, using modeled brightness temperatures (Tb) generated using a priori hurricane wind and rain fields that are statistically representative of the actual hurricane conditions at the time of the HIRAD brightness temperature measurements. For this calibration technique, the probability distribution function of the measured HIRAD Tb\u27s is matched to the modeled Tb distribution. After applying this Tb calibration, hurricane wind speeds and rain rates are retrieved for six hurricane surveillance flights between 2013-2015. These HIRAD results are compared with available, statistically independent, surface measurements from in-situ GPS dropwindsondes and remote sensing: Stepped Frequency Microwave Radiometer (SFMR), and the High-Altitude Imaging Wind and Rain Aerial Profiler (HIWRAP). Since there is good agreement in the intercomparisons, it is concluded that the HIRAD hurricane measurement technique performs as intended, after the corresponding Tb images are properly calibrated. Furthermore, based upon the above comparisons, it is concluded that the retrieved HIRAD 2-dimensional wind field improves upon the a priori calibration source, regardless of quality of this model used in the calibration. This shows that HIRAD is not simply replicating results of the calibration source, but rather, it adds useful information

Earth resources: A continuing bibliography with indexes (issue 61)

This bibliography lists 606 reports, articles, and other documents introduced into the NASA scientific and technical information system between January 1 and March 31, 1989. Emphasis is placed on the use of remote sensing and geophysical instrumentation in spacecraft and aircraft to survey and inventory natural resources and urban areas. Subject matter is grouped according to agriculture and forestry, environmental changes and cultural resources, geodesy and cartography, geology and mineral resources, oceanography and marine resources, hydrology and water management, data processing and distribution systems, and instrumentation and sensors, and economic analysis

J Atmos Ocean Technol

Surface wind speed retrievals have been generated and evaluated using Hurricane Imaging Radiometer (HIRAD) measurements from flights over Hurricane Joaquin, Hurricane Patricia, Hurricane Marty, and the remnants of Tropical Storm Erika, all in 2015. Procedures are described here for producing maps of brightness temperature, which are subsequently used for retrievals of surface wind speed and rain rate across a ~50 km wide swath for each flight leg. An iterative retrieval approach has been developed to take advantage of HIRAD's measurement characteristics. Validation of the wind speed retrievals has been conducted, using 636 dropsondes released from the same WB-57 high altitude aircraft carrying HIRAD during the Tropical Cyclone Intensity (TCI) experiment. The HIRAD wind speed retrievals exhibit very small bias relative to the dropsondes, for winds tropical storm strength (17.5 m s|) or greater. HIRAD has reduced sensitivity to winds weaker than tropical storm strength, and a small positive bias (~2 m s|) there. Two flights with predominantly weak winds according to the dropsondes have abnormally large errors from HIRAD, and large positive biases. From the other flights, root mean square differences between HIRAD and the dropsonde winds are 4.1 m s| (33%) for winds below tropical storm strength, 5.6 m s| (25%) for tropical storm strength winds, and 6.3 m s| (16%) for hurricane strength winds. Mean absolute differences for those categories are 3.2 m s| (25%), 4.3 m s| (19%), and 4.8 m s| (12%), with bias near zero for tropical storm and hurricane strength winds.20172018-08-01T00:00:00ZU01 IP000056/IP/NCIRD CDC HHS/United States28919665PMC5597242663

Earth resources: A continuing bibliography with indexes (issue 51)

This bibliography lists 382 reports, articles and other documents introduced into the NASA scientific and technical information system between July 1 and September 30, 1986. Emphasis is placed on the use of remote sensing and geophysical instrumentation in spacecraft and aircraft to survey and inventory natural resources and urban areas. Subject matter is grouped according to agriculture and forestry, environmental changes and cultural resources, geodesy and cartography, geology and mineral resources, hydrology and water management, data processing and distribution systems, instrumentation and sensors, and economic analysis

Hurricane Imaging Radiometer (HIRAD) Tropical Rainfall Retrievals

The Hurricane Imaging Radiometer (HIRAD) is an airborne passive microwave remote sensor, developed to measure wind speed and rain rate in hurricanes. This dissertation concerns the development of a signal processing algorithm to infer tropical rainfall from HIRAD radiance (brightness temperature, Tb) measurements. The basis of the rain rate retrieval algorithm is an improved forward microwave radiative transfer model (RTM) that incorporates the HIRAD multi-antenna-beam geometry, and uses semi-empirical coefficients derived from an airborne experiment that occurred in the Gulf of Mexico off Tampa Bay in 2013. During this flight, HIRAD observed a squall line of thunderstorms simultaneously with an airborne meteorological radar (High Altitude Wind and Rain Profiler, HIWRAP), located on the same airplane. Also, ground based NEXRAD radars from the National Weather Service (located at Tampa and Tallahassee) provided high resolution simultaneous rain rate measurements. Using NEXRAD rainfall as the surface truth input to the HIRAD RTM, empirical rain microwave absorption coefficients were tuned to match the measured brightness temperatures. Also, the collocated HIWRAP radar reflectivity (dBZ) measurements were cross correlated with NEXRAD to derive the empirical HIWRAP radar reflectivity to rain rate relationship. Finally, the HIRAD measured Tbs were input to the HIRAD rain retrieval algorithm to derive estimates of rain rate, which were validated using the independent HIWRAP measurements of rain rate

NASA oceanic processes program: Status report, fiscal year 1980

Goals, philosophy, and objectives of NASA's Oceanic Processes Program are presented as well as detailed information on flight projects, sensor developments, future prospects, individual investigator tasks, and recent publications. A special feature is a group of brief descriptions prepared by leaders in the oceanographic community of how remote sensing might impact various areas of oceanography during the coming decade

Laboratory for Atmospheres Instrument Systems Report

Studies of the atmospheres of our solar system's planets including our own require a comprehensive set of observations, relying on instruments on spacecraft, aircraft, balloons, and on the surface. These instrument systems perform one or both of the following: 1) provide information leading to a basic understanding of the relationship between atmospheric systems and processes, and 2) serve as calibration references for satellite instrument validation. Laboratory personnel define requirements, conceive concepts, and develop instrument systems for spaceflight missions, and for balloon, aircraft, and ground-based observations. Balloon and airborne platforms facilitate regional measurements of precipitation, cloud systems, and ozone from high-altitude vantage points, but still within the atmosphere. Such platforms serve as stepping-stones in the development of space instruments. Satellites provide nearly global coverage of the Earth with spatial resolutions and repetition rates that vary from system to system. The products of atmospheric remote sensing are invaluable for research associated with water vapor, ozone, trace gases, aerosol particles, clouds, precipitation, and the radiative and dynamic processes that affect the climate of the Earth. These parameters also provide the basic information needed to develop models of global atmospheric processes and weather and climate prediction. Laboratory scientists also participate in the design of data processing algorithms, calibration techniques, and the data processing systems

Earth resources: A continuing bibliography with indexes (issue 55)

This bibliography lists 368 reports, articles and other documents introduced into the NASA scientific and technical information system between July 1 and September 30, 1987. Emphasis is placed on the use of remote sensing and geographical instrumentation in spacecraft and aircraft to survey and inventory natural resources and urban areas. Subject matter is grouped according to agriculture and forestry, environmental changes and cultural resources, geodesy and cartography, geology and mineral resources, hydrology and water management, data processing and distribution systems, instrumentation and sensors, and economic analysis