HR: 1330h
AN: SH42A-0492    [PDF]
TI: Midlatitude D-Region Absorption Studies in the Space Weather Context - Observational Results
AU: Hunsucker, R
EM: Rdhrpc1@aol.com
AF: RP Consultants, 7917 Gearhart, Klamath Falls, OR 97601
AU: Sojka, J
EM: jan.sojka@spacenv.com
AF: Space Environment Corp., 221 N.Spring Creek Parkway, Suite A, Providence, UT 84332
AU: * Eccles, V
AF: RP Consultants, 7917 Gearhart, Klamath Falls, OR 97601
AB: Simultaneous continuous measurements of NOAA/GOES 8/10/12 solar x-ray flux and calibrated HF signal strength were initiated in December 2002 to provide validation data for a "Data Driven D-region (DDDR)" ionospheric model. One-minute signal strength averages of standard time-frequency stations WWV and WWVH over the range of 2.5 to 20.0 MHz and 5-minute averages of 1.0 to 8.0 nm solar x-ray flux have been studied for 35 solar flares ranging from Class C to Class X from March through August 2003 during the descending phase of solar cycle 23. Digital filtering of the received signals allows the individual transmissions to be positively identified, providing quantitative calibration of received signal and noise parameters. The monitoring stations are located at Providence, Utah and Klamath Falls, Oregon. An ionosonde and magnetometer at Bear Lake Observatory in Utah provide data about ionospheric conditions near the WWV to Klamath Falls path midpoint.Continuous monitoring at these stations is planned through August 2005. Not surprisingly, there appears to be a close association between the magnitude of the solar x-ray flares and HF signal attenuation on the midlatitude path from Fort Collins, Colorado (WWV) to both Providence and to Klamath Falls. On the 1400 km WWV to Klamath Falls path, effects are most closely related to daytime 10 and 15 MHz signal absorption. Relationships between x-ray flux, signal absorption, time of day and geomagnetic activity levels for the cases studied is presented.It is proposed that this type of HF signal monitoring can provide an inexpensive, passive, near-real-time data stream for assimilation into the DDDR model and possibly for HF propagation forecasting/nowcasting programs as well. Potential extensions to the monitoring program which could extend its usefulness beyond the American sector wil also be discussed.
DE: 2409 Current systems (2708)
DE: 2487 Wave propagation (6934)
DE: 7519 Flares
DE: 7823 Ionization processes
SC: SPA - Solar and Heliospheric Physics [SH]
MN: 2003 Fall Meeting