1. 1 Space Environment Corporation Investigation and Development of Data-Driven D-Region Model for HF Systems Impacts D. Rice Space Environment Corp., Providence, Utah R. D. Hunsucker RP Consultants, Klamath Falls, Oregon J. Eccles Space Environment Corp., Providence, Utah J. J. Sojka Space Environment Corp., Providence, Utah NASA - Living With A Star (from material presented at Spring AGU/Montreal)

2. 2 Space Environment Corporation Investigation and Development of Data-Driven D-Region Model for HF Systems Impacts Space Environment Corporation Vince Eccles Bob Hunsucker Don Rice Jan Sojka Developing a Data-Driven D-Region model for real-time HF absorption calculations with validation obtained from a low-cost HF-link monitoring network. NASA satellite data streams and HF monitoring experiment are used to determine D-Region specification during solar x-ray flares, particle events, winter absorption anomaly, sporadic E HF Link Monitoring (www.spacenv.com/~rice/hidive)

3. 3 Space Environment Corporation HF Propagation and Absorption Modeling The Data-Driven D-Region is combined with E and F Region model ionosphere (IRI, and others) to provide background for ray-tracing and absorption calculations. Results compared with HF-link Monitoring Experiments. F-Region E-Region D-Region

4. 4 Space Environment Corporation Modeling and Monitoring D-Region Weather Large space weather events are evident in 2003 data and model of 5000 kHz HF propagation characteristics Low frequency propagation at night due to daytime absorption. Most notably the “Halloween Storm” in October-November Nighttime variations in HF propagation cutoffs. Daytime absorption increases during winter anomaly events are easily identified. (Improvements of NO model density needed.) UT (hour) Day of 2003 Model Signal@KF Measured Signal@KF Model Signal@KF

5. 5 Space Environment Corporation Modeling and Monitoring E&F-Region Weather Space weather observed in 10000 kHz HF propagation characteristics. High frequency propagation during daytime only (generally) Solar rotation variation influence on ionosphere ionization rates. Sporadic E layer provides for low angle HF propagation during nighttime…not modeled. Diurnal and seasonal trends captured. UT (hour) Day of 2003 Measured Signal@KF Model Signal@KF