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Earth, Planets and Space
Fig. 5 | Earth, Planets and Space

Fig. 5

From: The ionospheric condition and GPS positioning performance during the 2013 tropical cyclone Usagi event in the Hong Kong region

Fig. 5

Time series of X-ray (a), solar X-ray flare count (b), and electron flux (c) during the period from 13 September to 11 October 2013, which were measured by the GOES 15 geostationary satellite. Solar X-ray flux (https://satdat.ngdc.noaa.gov/sem/goes/data/avg/2013/09/goes15/netcdf/) was measured at the wavelength of 0.1–0.8 nm. Solar X-ray flare counts (https://hesperia.gsfc.nasa.gov/goes/goes_event_listings/) are classified into 3 categories (C, M, and X classes of these flares). Electron flux (https://satdat.ngdc.noaa.gov/sem/goes/data/avg/2013/09/goes15/netcdf/) was measured at electron channels of E2 (> 2 meV). The life cycle of the Usagi was from 16 to 24 September 2013, as represented by the gray background area between two vertical red dashed lines. The vertical red solid line denotes the TC’s landfall near Hong Kong on 22 September 2013

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