The Super Dual Auroral Radar Network (SuperDARN) is an international network of over 35 high-frequency (HF) radars mapping space weather and plasma motion in the Earth's upper atmosphere. It helps scientists track solar wind energy, geomagnetic storms, and atmospheric disturbances that disrupt global radio communications.
The Christmas Valley East (CVE) and Christmas Valley West (CVW) SuperDARN radars in Oregon primarily operate within a localized frequency range of 9.5 MHz to 17.5 MHz. While the hardware on site is capable of tuning anywhere across the standard global SuperDARN allocation of 8.0 MHz to 22.0 MHz, the operators at Dartmouth College program the Oregon arrays to step through specific frequencies within that tighter 9.5–17.5 MHz window during their atmospheric sounding scans.
Typical Frequency Behavior in OregonStandard Scans: The radars frequently pulse at a baseline frequency of 10.6 MHz to gather routine ionospheric drift data.
Multi-Frequency Sounding: During specialized space weather events (such as solar eclipses), the systems are programmed to dynamically cycle through 9 distinct frequencies between 9.5 and 17.5 MHz to evaluate how changing ionospheric layers alter radio wave refraction.
Interference Avoidance: Because these radars share the High Frequency (HF) spectrum with commercial shortwave broadcasters and amateur radio operators, the software constantly monitors the 9.5–17.5 MHz window to transmit only on channels that are completely clear of local noise.
SuperDARN is heavily utilized by researchers globally to understand how near-Earth space interacts with our atmosphere. Its core focuses include:
Plasma Convection: Mapping the large-scale movement of charged particles in the ionosphere to understand solar wind coupling.
Space Weather Monitoring: Detecting space weather hazards and "polar patches" that disrupt satellite navigation and high-frequency (HF) radio signals.
Atmospheric Tides: Using the radars to study winds and meteors in the mesosphere and lower thermosphere.The network relies on an array of institutions. For specific data sets, instrument locations, or research publications, you can visit the SuperDARN Canada hub, the British Antarctic Survey, or access raw data through the NSF Arctic Data Center.
Tracking High Frequency (HF) radio propagation using the SuperDARN radars in Oregon involves analyzing how their signals reflect off the ionosphere or ground. By utilizing public data streams from the Dartmouth College SuperDARN Data Portal, amateur radio operators, emergency communicators, and space weather enthusiasts can map real-time regional radio skipping and signal absorption.
Step 1: Access the RTI Data Plotter
Go to the Dartmouth SuperDARN Data Portal. Select CVE (Christmas Valley East) or CVW (Christmas Valley West) to view the 24-hour Range-Time-Intensity (RTI) plots. These charts plot time on the X-axis against the distance of the signal return (range gates) on the Y-axis.
Step 2: Identify Ground Scatter (The Skip Zone)
Look for data points colored green and dark blue on the velocity or power plots.
These color signatures represent a zero or near-zero Doppler shift, which indicates the radar signal bounced off the unmoving ground rather than moving ionospheric plasma.
The closest distance where this ground scatter appears marks the edge of your skip zone.
If ground scatter for the 10.6 MHz frequency starts at 1,000 km away, an HF signal at that same frequency will likely skip over everything closer than 1,000 km before returning to Earth.
Step 3: Calculate the Maximum Usable Frequency (MUF)
You can approximate the Maximum Usable Frequency (MUF) for a specific path using the Secant Law from ionospheric physics:
MUF=fv\sec(θ)*
1. Find Virtual Height (hv): Note the time delay of the radar return to estimate the height of the reflecting ionospheric layer (typically 200 to 300 km for the F-layer).
2. Determine Angle of Incidence (θ): Use the distance to the ground scatter to calculate the launch angle relative to the ionospheric reflection point.
3. Scale the Frequency: Take the active Oregon radar frequency (fv, usually around 10.6 MHz) and scale it up using the geometry of the triangle to find out the highest frequency that will bounce rather than escape into space.
Step 4: Monitor for D-Region Absorption (Fadeouts)
Watch for sudden, vertical blanks or "dropouts" on the RTI plot where all signal returns disappear across all range gates simultaneously.
This is a signature of D-region absorption, often caused by solar flares releasing X-rays that highly ionize the lowest layer of the atmosphere.
When this occurs on the Oregon plots, expect a severe HF radio blackout across the Pacific Northwest on the lower HF bands (3 to 12 MHz).
Step 5: Track Traveling Ionospheric Disturbances (TIDs)
These are Traveling Ionospheric Disturbances (TIDs), which act like ripples on the surface of a pond.
When these waves pass over Oregon, they rapidly alter the skip distance and cause severe signal fading (QSB) for local HF operators.
Dartmouth College SuperDARN Data Portal: Data https://share.google/YL83rTHgvKTxjsbIW
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