T. Ogawa1, T. Adachi2, and N. Nishitani3

1) NICT, Japan 2) Stanford Univ., USA 3) STE Lab., Nagoya Univ., Japan

Medium-Scale Traveling Ionospheric Disturbances Simultaneously Observed With the SuperDARN

Hokkaido Radar and FORMOSAT/ISUAL

SuperDARN Workshop 2011 Hanover, US 30 May – 3 June 2010

・ SuperDARN Hokkaido HF Radar Imaging of horizontal two-dimensional MSTID structures over the Sea of Okhotsk from the north of Hokkaido to Kamchatka

・ FORMSAT-2 / ISUAL 630-nm Limb Imager Imaging of two-dimensional 630-nm airglow structures in the vertical along satellite path

・ Using the ISUAL imager and ground-based all-sky imager at Darwin, Adachi et al. (2011) first clarified three-dimensional 630-nm airglow structures.

・ In this presentation, we use the Hokkaido radar, ISUAL limb imager, and GPS-TEC data to investigate propagation and three-dimensional structure of MSTID.

ISUAL (Imager for Sprites :Upper Atmospheric

Lightning)

FORMOSAT-2

ISUAL 630-nmLimb Imager

SuperDARN Hokkaido Radar

GEONET Providing GPS-TEC DataOver Japan

~1,200 Rxs

Rikubetsu (43.53oN, 143.61oE; geomag. 36.46oN)

ISUAL 630-nmLimb Imager(h ~ 900 km)

MSTID

～5000 km

～6000 km

Long-Distance Propagation of Nighttime MSTID（ HF Radar + GPS + 630-nm Imager ）

Long-Distance Propagation of Nighttime MSTID（ HF Radar + GPS + 630-nm Imager ）

(Ogawa et al., 2009)

Winter Night Summer Night

Range Res. = 45 km, Time Res. = 1 min20 December 2006

1520 UT

GPS-TEC Map at 1520 UT

1520 UT

1456 UT

Kp = 4-, 4-Dst = -26

(disturbed)

HF FOV

Satellite Track

1522:29

1456:49

Limb Obs.

20 Dec2006

B0

B15

1522 UT

Range Res. = 45 kmTime Res. = 1 min

10.8 MHz

1516 UT 1519 UT 1522 UT

20 December 2006

MSTID observed with radar and GEONET Velocity : ~90 m/s toward SW Period ： ~50 min Wavelengths ： ~270 - 500 km

B8

Echo Power

Doppler Velocity

Beam 8

630-nmDeviation

N-S wavelengthsof ~100 - 500 km

Range Res. = 15 km, Time Res. = 1 min29 December 2008

1325 UT

GPS-TEC Map at 1325 UT

Kp = 0, 0+(very quiet)

1325 UTFaint MSTID

1304 UT1332 UT

HF FOV

1332:35

1304:34

B0

B15

29 Dec2008

Satellite Track

Limb Obs.

Range Res. = 15 km, Time Res. = 1 min

10.8 MHz

1322 UT 1325 UT 1329 UT29 December 2008

1332 UT

MSTID structures are unclear compared withthose on 20 and 21 December 2006 Wavelength : ~500 km

B5

Echo Power

Doppler Velocity

Beam 5

N-S wavelengthof ~ 500 km

Small-scalestructures withwavelengths ofa few tens to100 km

Echoes return fromstrong horizontalgradients of Ne?

Winter Nighttime MSTID

(Ogawa et al., 2009)

Strong radar echoes tend to have negativeDoppler velocities ?

MSTID

SW

E

N

Limb-view Obs.

FO

RM

OS

AT

-2 /

ISU

AL Limb-view Obs.

The ISUAL imager cannot always clarify discrete MSTID structures when its field-of-view is not aligned with phase fronts of MSTID, in particular, in the case of 29 Dec. 2008

Latitude

Alti

tude

MSTID

630-nm (Ne) Vertical StructureSeen by ISUAL

・ On 20 and 21 December 2006 (geomagnetically disturbed days), the Hokkaido HF radar detected southwestward-propagating MSTID with phase velocities of ~80-90 m/s, a period of ~50 min, and wavelengths of ~200-500 km. The ISUAL limb imager simultaneously observed airglow structures along N-S with horizontal wavelengths of ~100-500 km that were also seen in the radar data, though the imager FOVs were ~ 1000 km (or more) west of the radar FOV.

・ On 29 December 2008 (geomagnetically quiet day), the imager FOVs were within the

radar FOV. Though MSTID signatures were rather faint, MSTID with a wavelength of ~500 km were observed with both the radar and imager. Both instruments also detected small-scale structures with wavelengths of a few tens to 100 km embedded within MSTID. Strong radar echoes tend to have negative Doppler velocities.

・ Thus, MSTID signatures observed with the radar seem to correspond to those detected with the ISUAL imager, though the imager cannot always clarify discrete MSTID structures when its FOV is not aligned with phase fronts of MSTID.

・ More simultaneous observations are required to investigate spatial relationship between radar (radio wave) and imager (optical) MSTID, and to know those between Ne irregularities and 630-nm airglow structures.

Summary