edu.ucar.opensky::articles:24670 UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact 2025-12-24T23:07:07.897871 ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data ISO 19115-2:2009(E) https://n2t.org/ark:/85065/d7wd441z https://doi.org/10.5065/D6RX99HX https Related Service #1 Cheyenne: SGI ICE XA Cluster https://doi.org/10.5281/zenodo.1256921 https Related Software #1 drsteve/PyForecastTools: Version 1.1.1 The role of flare-driven ionospheric electron density changes on the doppler flash observed by SuperDARN HF radars 2021-08-01T00:00:00Z publication https://n2t.org/ark:/85065/d7wd441z https://doi.org/10.1029/2021JA029300 Chakraborty, S. author Qian, Liying author Ruohoniemi, J. M. author Baker, J. B. H. author McInerney, Joseph author Nishitani, N. author UCAR/NCAR - Library publisher Trans-ionospheric high frequency (HF: 3-30 MHz) signals experience strong attenuation following a solar flare-driven sudden ionospheric disturbance (SID). Solar flare-driven HF absorption, referred to as short-wave fadeout, is a well-known impact of SIDs, but the initial Doppler frequency shift phenomena, also known as "Doppler flash" in the traveling radio wave is not well understood. This study seeks to advance our understanding of the initial impacts of solar flare-driven SID using a physics-based whole atmosphere model for a specific solar flare event. First, we demonstrate that the Doppler flash phenomenon observed by Super Dual Auroral Radar Network (SuperDARN) radars can be successfully reproduced using first-principles based modeling. The output from the simulation is validated against SuperDARN line-of-sight Doppler velocity measurements. We then examine which region of the ionosphere, D, E, or F, makes the largest contribution to the Doppler flash. We also consider the relative contribution of change in refractive index through the ionospheric layers versus lowered reflection height. We find: (a) the model is able to reproduce radar observations with an root-median-squared-error and a mean percentage error (delta) of 3.72 m/s and 0.67%, respectively; (b) the F-region is the most significant contributor to the total Doppler flash (similar to 48%), 30% of which is contributed by the change in F-region's refractive index, while the other similar to 18% is due to change in ray reflection height. Our analysis shows lowering of the F-region's ray reflection point is a secondary driver compared to the change in refractive index. UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact PDF Text theme Resource Type 2016-01-01T00:00:00Z publication Copyright 2021 American Geophysical Union. None eng geoscientificInformation