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  • 1
    Publication Date: 2019-07-19
    Description: The Hurricane Imaging Radiometer (HIRAD) is an experimental C-band passive microwave radiometer designed to map the horizontal structure of surface wind speed fields in hurricanes. New data processing and customized retrieval approaches were developed after the 2015 Tropical Cyclone Intensity (TCI) experiment, which featured flights over Hurricanes Patricia, Joaquin, Marty, and the remnants of Tropical Storm Erika. These new approaches produced maps of surface wind speed that looked more realistic than those from previous campaigns. Dropsondes from the High Definition Sounding System (HDSS) that was flown with HIRAD on a WB-57 high altitude aircraft in TCI were used to assess the quality of the HIRAD wind speed retrievals. The root mean square difference between HIRAD-retrieved surface wind speeds and dropsonde-estimated surface wind speeds was 6.0 meters per second. The largest differences between HIRAD and dropsonde winds were from data points where storm motion during dropsonde descent compromised the validity of the comparisons. Accounting for this and for uncertainty in the dropsonde measurements themselves, we estimate the root mean square error for the HIRAD retrievals as around 4.7 meters per second. Prior to the 2015 TCI experiment, HIRAD had previously flown on the WB-57 for missions across Hurricanes Gonzalo (2014), Earl (2010), and Karl (2010). Configuration of the instrument was not identical to the 2015 flights, but the methods devised after the 2015 flights may be applied to that previous data in an attempt to improve retrievals from those cases.
    Keywords: Meteorology and Climatology
    Type: MSFC-E-DAA-TN48243 , Conference on Hurricanes and Tropical Meteorology; Apr 16, 2018 - Apr 20, 2018; Ponte Vedra, FL; United States
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  • 2
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Meteorology and Climatology
    Type: MSFC-E-DAA-TN21161 , Interdepartmental Hurricane Conference; Mar 02, 2015 - Mar 05, 2015; Jacksonville, FL; United States
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  • 3
    Publication Date: 2019-07-13
    Description: The NASA Hurricane and Severe Storm Sentinel (HS3) mission is an aircraft field measurements program using NASA's unmanned Global Hawk aircraft system for remote sensing and in situ observations of Atlantic and Caribbean Sea hurricanes. One of the principal microwave instruments is the Hurricane Imaging Radiometer (HIRAD), which measures surface wind speeds and rain rates. For validation of the HIRAD wind speed measurement in hurricanes, there exists a comprehensive set of comparisons with the Stepped Frequency Microwave Radiometer (SFMR) with in situ GPS dropwindsondes [1]. However, for rain rate measurements, there are only indirect correlations with rain imagery from other HS3 remote sensors (e.g., the dual-frequency Ka- & Ku-band doppler radar, HIWRAP), which is only qualitative in nature. However, this paper presents results from an unplanned rain rate measurement validation opportunity that occurred in 2013, when HIRAD flew over an intense tropical squall line that was simultaneously observed by the Tampa NEXRAD meteorological radar (Fig. 1). During this experiment, Global Hawk flying at an altitude of 18 km made 3 passes over the rapidly propagating thunderstorm, while the TAMPA NEXRAD perform volume scans on a 5-minute interval. Using the well-documented NEXRAD Z-R relationship, 2D images of rain rate (mm/hr) were obtained at two altitudes (3 km & 6 km), which serve as surface truth for the HIRAD rain rate retrievals. A preliminary comparison of HIRAD rain rate retrievals (image) for the first pass and the corresponding closest NEXRAD rain image is presented in Fig. 2 & 3. This paper describes the HIRAD instrument, which 1D synthetic-aperture thinned array radiometer (STAR) developed by NASA Marshall Space Flight Center [2]. The rain rate retrieval algorithm, developed by Amarin et al. [3], is based on the maximum likelihood estimation (MLE) technique, which compares the observed Tb's at the HIRAD operating frequencies of 4, 5, 6 and 6.6 GHz with corresponding theoretical Tb values from a forward radiative transfer model (RTM). The optimum solution is the integrated rain rate that minimizes the difference between RTM and observed values. Because the excess Tb from rain comes from the direct upwelling and the indirect reflected downwelling paths through the atmosphere, there are several assumptions made for the 2D rain distribution in the antenna incident plane (crosstrack to flight direction). The opportunity to knowing 2D rain surface truth from NEXRAD at two different altitudes will enable a comprehensive evaluation to be preformed and reported in this paper.
    Keywords: Meteorology and Climatology
    Type: MSFC-E-DAA-TN20510 , IGARSS 2015; Jul 26, 2015 - Jul 31, 2015; Milan; Italy
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  • 4
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Meteorology and Climatology
    Type: MSFC-E-DAA-TN54620 , Conference on Hurricanes and Tropical Meteorology; Apr 16, 2018 - Apr 20, 2018; Ponte Vedra, FL; United States
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  • 5
    Publication Date: 2019-08-13
    Description: No abstract available
    Keywords: Meteorology and Climatology
    Type: MSFC-E-DAA-TN22662 , HS3 / HSRP Science Team Meeting; May 06, 2015; Mountain View, CA; United States
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  • 6
    Publication Date: 2019-07-13
    Description: Purpose of this talk is to give an overview of the HIRAD "catalog" of data available for analysis.
    Keywords: Meteorology and Climatology
    Type: MSFC-E-DAA-TN33174 , Workshop on "Integrating Satellite Observations and Airborne Data with Model Forecast to Understand Hurricane Processes and Evaluate Models"; Jun 21, 2016 - Jun 23, 2016; Pasadena, CA; United States
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  • 7
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Meteorology and Climatology
    Type: MSFC-E-DAA-TN36496 , TCI Science Team Meeting; Oct 18, 2016 - Oct 19, 2016; Boulder, CO; United States
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  • 8
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Meteorology and Climatology
    Type: MSFC-E-DAA-TN31538 , Conference on Hurricanes and Tropical Meteorology; Apr 17, 2016 - Apr 22, 2016; San Juan, PR; United States
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  • 9
    Publication Date: 2019-07-13
    Description: On board of the NASA's Global Hawk (AV1) aircraft there are two microwave, namely: the passive microwave Hurricane Imaging Radiometer (HIRAD), and the active microwave High-altitude Imaging Wind and Rain Airborne Profiler (HIWRAP). This paper presents results from an unplanned rain rate measurement validation opportunity that occurred in 2013, when the Global Hawk aircraft flew over an intense tropical squall-line that was simultaneously observed, by the Tampa NEXRAD meteorological radar. During this experiment, Global Hawk flying at an altitude of 18 km made 3 passes over the rapidly propagating thunderstorm, while the TAMPA NEXRAD perform volume scans on a 5-minute interval. NEXRAD 2D images of rain rate (mm/hr) were obtained at two altitudes (3 km & 6 km), which serve as surface truth for the HIRAD rain rate retrievals. In this paper, results are presented of the three-way inter-comparison of HIRAD Tb, HIWRAP dbZ and NEXRAD rain rate imagery.
    Keywords: Meteorology and Climatology
    Type: MSFC-E-DAA-TN25106 , IGARSS 2015; Jul 26, 2015 - Jul 31, 2015; Milan; Italy
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  • 10
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Meteorology and Climatology
    Type: MSFC-E-DAA-TN28924 , Conference on Integrated Observing and Assimilation Systems for Atmosphere, Oceans, and Land Surface (IOAS-AOLS); Jan 10, 2016 - Jan 14, 2016; New Orleans, LA; United States
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