K. Fujiki, H. Ito, M. Tokumaru

Solar-Terrestrial Environment Laboratory (STELab),

Nagoya University.

SOLAR WIND FORECAST BY USING INTERPLANETARY SCINTILLATION

OBSERVATIONS

Given by M. M. Bisi

Center for Astrophysics and Space Sciences, University of California, San Diego.

Earth

IPS LOS

Real-time tomography analysisReal-time tomography analysis

Lines of sight fulfill interplanetary space inside 1 AU by observing IPS sources over one solar rotation (left panel).

•Forecast on Oct 7, 2005.Forecast on Oct 7, 2005.

ACE

Forecast

Forecast

• Quantitative verification of IPS forecast.Quantitative verification of IPS forecast.

• Forecast Error: Forecast Error:

IPS forecasts on July-October, 2005 are IPS forecasts on July-October, 2005 are compared with ACE data.compared with ACE data.

• Cause of the error;Cause of the error;

CME;CME;

Sunspot number;Sunspot number;

Number of LOS;Number of LOS;

etc…etc…

ObjectiveObjective

Method

LOS obtained in Oct 7 mapped on 1AULOS obtained in Oct 7 mapped on 1AU

Earth position

Forecastable

Forecastable periodForecastable period

Forecastable period7.2 days

• Differences between IPS forecast and ACE Differences between IPS forecast and ACE data.data.

100km/s

|VIPS-VACE|~87.7km/s

Daily variation of Averaged difference between IPS and ACEAveraged difference between IPS and ACE

Daily variation of correlation coefficient between IPS Forecast and ACE

Orange ： high correlation and small difference.

Blue ： Low correlation and large difference.

Number of LOS during 3 days past.

Number of LOS at forecast date

Number of LOS is small.Number of LOS is small.

IPS Forecast Error and Number of LOS

Forecast error does not depend on solar transient activity.

Number of CMEs and sunspots during

3 days past.

IPS Forecast Error and Transient activities

• Verifications of IPS solar wind forecast are carried Verifications of IPS solar wind forecast are carried out by using IPS and ACE data obtained from July out by using IPS and ACE data obtained from July through October 2005 (near solar minimum).through October 2005 (near solar minimum).

• Forecastable period:Forecastable period:7days (avg.), 13days(max).7days (avg.), 13days(max).

• Good accuracy period:Good accuracy period: ~6days (|V~6days (|VIPSIPS-V-VACEACE|<100km/s).|<100km/s).

• Stable condition of IPS observations is essentially Stable condition of IPS observations is essentially important to forecast solar wind with good important to forecast solar wind with good accuracy.accuracy.

SummarySummary