Ionospheric-magnetospheric VLF Wave Propagation: RPI/IMAGE-HAARP Correlative StudyV. Paznukhov, B. Reinisch, G. Sales, P. Song, G. KhmyrovCenter for Atmospheric ResearchUniversity of Massachusetts Lowell

P. KosseyAir Force Research Laboratory

ObjectivesUse RPI/IMAGE to monitor the global network of VLF transmitters.Study the power and effective spatial scales of the propagating whistler waves in magnetosphere.Assess the effects of the waves to the radiation belt particles.

Radiation belt energetic electron lifetimes(after Abel and Thorne, 1998)C: coulombH: hissW: lightning whistlerVLF: ground transmittersL-shellPrecipitation lifetime (days)

VL3-13.0GBR-16.0JXN-16.4VTX3-18.2HWU-18.3, 20.9, 21.7GQD-19.6NWC-19.8ICV-20.273SA-20.6JJI-22.2DHO-23.4NAA-24.0NLK-24.8PWB-25.0NML-25.2TBB-26.7Worldwide Map of Active VLF StationsHAARP

203040506070210240270300330Maine, NAA 24.0 kHz (44.5 N, 291 E)Seattle, NLK 24.8 kHz (48.0 N, 238 E)year 20010424 UT0600 UT0438 UTMarch 261600 UT1544 UT1400 UTIMAGE Magnetic Field FootprintsApril 40056 UT0034 UT2300 UTFebruary 14/15 NLKNAAGEO Longitude, degGEO Latitude, deg

Seattle, NLK 24.8Example of dynamic spectrum

Seattle, NLK 24.8Example of dynamic spectrum

Maine, NAA 24.0Example of dynamic spectrum

Observations of ground based VLF stationsNLK 24.8 kHzNAA 24 kHz

24.8 kHz (NLK station) and 27.4 kHz (noise) signal comparison NLK 24.8 kHz27.4 kHz

24.0 kHz (NAA station) and 27.4 kHz (noise) signal comparison NAA 24.0 kHz27.4 kHz

Observations of NLK stationNLK 24.8 kHzNLK 24.8 kHz

Observations of NAA stationNAA 24.0 kHzNAA 24.0 kHz

Observations of NAA stationNAA 24.0 kHzNAA 24.0 kHz

Spring 2001 Campaign: March 18 to April 7, 2001. HAARP was transmitting amplitude modulated HF signals in order to produce VLF plasma waves using the so-called Polar Electrojet Antenna.

RPI was set to receive the HAARP transmissions in both fixed frequencies and dynamic spectra.

HAARP heater transmitted 3.2 MHz signal modulated with 13 kHz sine wave.

During the experiments, the modulation frequency was alternatingly switched on and off in order for RPI to distinguish HAARP signals from background noise.HAARP-RPI Transmission Experiment

Geomagnetic Environment of HAARP-RPI Experiments 2001

HAARP Spring 2001 CampaignProgram 23dayside pathnightside path03/24HAARPHAARPHAARP

March 24, 2001 Dynamic Spectra measurementsAmplitude, nV/m

March 24, 2001 fixed frequency measurementsAmplitude, dB

Summary Whistler-mode radio waves originated from two ground-based VLF transmitters were detected by the RPI instrument.

Observed signal-to-noise ratio was of the order of 20 dB.

The observed VLF signal region was smaller during the dayside measurements than during the nightside ones.

In the HAARP-RPI experiments, fixed frequency measurements showed ambiguous signals. indication was found in the dynamic spectra mode of observation during a geomagnetically quiet period. evidence for the timing was ambiguous.

ObjectiveUsing the available global network of VLF transmitters, we monitor the occurrence of whistler-mode signals received with the RPI instrument onboard of IMAGE satellite.

The receiving mode is the DYNAMIC SPECTRA sweeping over the frequency band from 3kHz to 1MHz every 3 or 4 minutes. In the VLF band the frequency resolution is ~ 400 Hz.

Expected bandwidth of the VLF signals is of the order of a few hundred hertz.

Identified 21 stations from 13 kHz to 27 kHz with L-shells ranging from 1.11 to 5.24. Ten of these stations have high radiated power: 200 kW to 1 MW.

Radiation belt energetic electron lifetimes(after Abel and Thorne, 1998)

HAARP Spring 2001 CampaignProgram 49dayside pathnightside path