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September 25 1998 Magnetic Storm

Irkutsk/Millstone Observations of Coherent Backscatter

Experiment Overview

Diagnostic Data

Millstone Hill Data

ISTP Irkutsk Radar Data

John Foster's Homepage

October 98 (WLS) Campaign

April 98 (WLS98) Campaign

Storm Analysis: Hot News

Strong coherent backscatter from E-region heights was observed in low-elevation sidelobes by the Irkutsk ISR associated with the storm intensification at ~08:30 UT on Sept. 25, 1998.
Intense electric fields and sunward plasma convection associated with a storm-induced SAID event were observed by DMSP overflights in the region immediately poleward of the ISTP radar site
Three consecutive passes with the DMSP F-14 VIS imager monitored the extent of aurtoral precipitation over Siberia
Variation of backscattered coherent power versus range observed at Irkutsk is attributed to the variation of magnetic aspect angle sensitivity (theoretical) across the region. Nearly perfect comparison of theoretical aspect sensitivity profile with observed power profile CONFIRMS the -15 dB/deg aspect angle dependence for small aspect angles (< 3 deg) reported by Foster et al from Millstone Hill observations.

Analysis of Irkutsk coherent backscatter by Don Moorcroft

September 98 Storm: Overview

Storm onset took place during the MLTCS World Day radar operations. Strong coherent backscatter from E-region heights was observed in low-elevation sidelobes by the Irkutsk ISR associated with the storm intensification at ~08:30 UT on Sept. 25, 1998. Sidelobe coherent echoes wer observed from Millstone Hill beginning at the same time.

ISTP/Irkutsk Radar is situated at 52N latitude, 104 E longitude
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ISTP Irkutsk Radar Data

Data and plots provided by Oleg Berngardt, Boris Shpynev, and Alexander Potekhin

Irkutsk Radar Power vs altitude/range. Effects of Faraday rotation evident in F-region returns.
Variation of aspect angle sensitivity (theoretical) versus range North from the ISTP radar site
Variation of backscattered power (observed) shows all major features of aspect-sensitivity dependence
Variation of aspect angle at fixed range versus azimuth [black=550 km; red=830 km; magenta = 400 km]
Variation of aspect vs AZ and Range (absolute value of aspect over range [0,3] deg.
Variation of aspect vs AZ and EL (absolute value of aspect over range [0,12] deg.

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Millstone Radar Oct98 Observations

Zenith Antenna: Altitude variation of ionospheric parameters above Millstone Hill Sept 25, 1998 storm onset.
Zenith Antenna: 06-07 UT evidence of preciitation at F-region heights with dropout of spepctral fitting.
Postion Scans: log10 Density [10,12] (m-3)
Postion Scans: LOS Velocity [-1000,1000] (m/s)
Position-Mode data: @ 4 deg AzimuthT shows coherent returns in lowest gates after 02 UT and again after 08:30 UT.
Position-Mode data: @ 319 deg AzimuthT

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Diagnostic Data: September 1998 Experiment

Northern Hemisphere DMSP data provided by Fred Rich

Northern Hemisphere DMSP F11 and F13 passes

Southern Hemisphere DMSP data

POLAR UVI: auroral images over Siberia 11:12 UT - 13:20 UT.
DMSP F14 VIS images over Asian sector
DMSP F12 VIS images North of Lake Baikal
DMSP Pass: F11 @ 0908-0935 UT
DMSP Pass: F11 @ 1050-1108 UT
DMSP Pass: F13 @ 0924-0951 UT
DMSP Pass: F13 @ 1106-1133 UT
DMSP Drift meter: F11 @ 0912 UT near 136 E longitude
DMSP Drift meter: F11 @ 1054 UT near 113 E longitude
DMSP Drift meter: F13 @ 0926 UT near 112 E longitude
DMSP Drift meter: F13 @ 1110 UT near 86 E longitude
Magnetogram: Leirvogur 64N 338E 72 mlat
Magnetogram: Memambetsu 44N 133E 35 mlat
Provisional AE Index: 09/25/98

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September 25, 1998 Disturbance

Sep 25 98: Strong disturbance with Kp=9 occurs in response to solar disturbance during recurrent-activity interval one month prior to planned campaign.
Sep 25 98: Global auroral activity follows onset near 02 UT.
Sep 25 98: Millstone Local density and electron temperature indicate the rapid formation of a deep ionospheric trough at the latitude of intense convection > 1500 m/s.
Sep 25 98: Solar Wind Disturbance is associated with a dropout of ACE SW plasma detector (comparison with WIND observations indicates dropout at the time of high-speed stream arrival).
Sep 25 98: IMF disturbance included increase in |B| and fluctuating Bz.
Interplanetary data from ACE for recent MLTCS experiment Return to top

http://www.haystack.edu/~jcf/sep98.htm -- Revised: April 12, 1999.jcf@haystack.mit.edu