Wave Injection at Low Latitudes

Mark Golkowski

Remediation of Enhanced Radiation Belts Workshop

Lake Arrowhead, CA

March 3-6, 2007

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Adelaide, Australia

~500 kW ? Navigation transmitter in Komsomolsk na Amur in Russian far east (400 msec pulses) at L = 2

Conjugate point in southern Australia

Stanford University receiver since January 2007

Explore and quantify wave-growth

Stanford Scientists Kangaroos

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Russian Alpha Transmitters

3.6 second pattern (six 0.6s segments) 400ms pulses, 200ms off between pulses Three sites alternate among 3 frequencies

14.88 kHz

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Historical Background

Triggered emissions have been observed from other mid-latitude transmitters: NAA (L=2) 14.5 kHz, 200 msec pulses

Whistler-mode Komsomolsk Alpha pulses have been studied by Tanaka et al. 1987 in the context of whistler propagation characteristics

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Example 1-Hop

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2

1A

Becc

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Temporal (non-linear) Growth

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Example Growth

~7-8 dB total

~70-80 dB/sec

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Example Growth

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Example Detection

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10-Day Statistics (1-10 April)

Count of 1-hop observations in synoptic (1min/5min) recordings

10 days during and after a geomagnetic disturbance

1-Hop observations show qualitative relationship to geomagnetic activity

Need more data to quantify relationship

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Diurnal patterns

Day DayNight Day DayNight

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Average Daily Variations

Sunrise

Sunset

Tanaka et al. 1987 Stanford 2008

Diurnal variation shows maxima after sunset and sunrise

Tanaka et al. 1987: diurnal variation is same for whistlers and is a propagation effect (duct formation, coupling in/out of duct)

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Summary

1-Hop echoes regularly observed from Komsomolsk Alpha transmitter

Echoes exhibit temporal growth of ~70-80 dB/sec Propagation delays of 460 msec – 540msec

equatorial electron concentrations of 4000-5000 cm-3 at L = 2

Triggered of frequency emmisions not observed yet, except perhaps on DEMETER satellite

Diurnal variations likely result from propagation/ducting effects

Future Work: statistically quantify effect of geomagnetic conditions on wave growth