An Assessment of CYGNSS Normalized Bistatic Radar Cross Section Calibration
| Autor: | Faozi Said, Paul Chang, Seubson Soisuvarn, Zorana Jelenak |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Physics
Atmospheric Science 010504 meteorology & atmospheric sciences business.industry 0211 other engineering and technologies Sigma Ranging 02 engineering and technology Effective radiated power 01 natural sciences Noise floor Standard deviation Bin Computational physics Calibration Global Positioning System Computers in Earth Sciences business 021101 geological & geomatics engineering 0105 earth and related environmental sciences |
| Zdroj: | IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing. 12:50-65 |
| ISSN: | 2151-1535 1939-1404 |
| Popis: | A cyclone global navigation satellite system (CYGNSS) $\sigma _o$ calibration analysis is presented using version 2.0 of the Level 1 dataset available on PO.DAAC. Three separate analyzes are conducted, namely, an examination of the specular bin location (in delay) and $\sigma _o$ relationship, an investigation of the impact of recently improved characterizations of the GPS effective isotropically radiated power on CYGNSS $\sigma _o$ , and an intersatellite $\sigma _o$ calibration analysis. We first noted a correlation between the specular delay bin location and $\sigma _o$ , where an increase in the specular delay bin resulted in an increase in $\sigma _o$ regardless of the wind speed level; a specular delay bin location ranging from 4.75 to 5.00 and from 7.00 to 7.25 resulted in a 14.74 and 17.72 dB median $\sigma _o$ , respectively. Noticeable improvements in the median $\sigma _o$ were present in the version 2.0 dataset, when separating the data by GPS block type: for blocks IIR, IIF, and IIR-M, median $\sigma _o$ were 15.39, 15.42, and 15.10 dB, respectively (compared to 19.38, 20.53, and 21.38 dB in version 1.1). Finally, an unexpected correlation between the instrument noise floor and $\sigma _o$ was observed for all eight observatories while conducting the intersatellite $\sigma _o$ calibration analysis. Approximately 0–1 dB absolute $\sigma _o$ difference biases (with up to $\sim$ 1 dB standard deviation) between spacecrafts were observed. A report of this analysis was presented to CYGNSS scientists and engineers, who eventually found an issue with the D/A DDM scaling algorithm. We expect better statistical performances in future releases of the data. |
| Databáze: | OpenAIRE |
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