17:15 〜 18:30
[PEM10-P08] Calculation of solar surface flow using a magnetic element tracking module
キーワード：太陽、黒点、磁場
Solar flares have major impacts on the geospace electromagnetic environment. Flares are now believed to occur in conjunction with sunspot’s activities. The number of sunspots increases and decreases periodically in about eleven years. For the long-term space weather forecast, it is important to predict the sunspot number for the next solar cycle. Recently, it has been suggested that the polar magnetic field during the cycle minimum is one of the good precursors for the solar activity of the next cycle. The surface flux transport (SFT) model has been used to predict the polar magnetic field prior to the cycle minimum. While the SFT model requires several parameters, such as meridional flow, differential rotation, and turbulent diffusion, these parameters are not fully understood, especially on their temporal variation and the behavior in the polar region.
In this study, we focused on two typical solar surface flows, differential rotation and meridional circulation, which are the parameters of the SFT model. We apply a magnetic element tracking (MET) module on the SDO/HMI magnetogram to estimate the solar surface velocities. The polar region is difficult to be observed in the low resolution HMI data. We use the high resolution Hinode/SOT magnetogram to measure the surface motion in the polar region. The alignment of the SOT data was performed in comparison with the HMI data. Because the HMI data is available since 2010, we calculated solar surface flows for the entire period of solar cycle 24. As a result, we obtained the latitudinal profile and time variation of the meridional flow and differential rotation rate. We find that the differential rotation/meridional flow is faster/slower at the latitude where the sunspots frequently emerge, respectively[YM1] . From the Hinode/SOT data, we calculated solar surface flow in the polar region with higher spatio-temporal resolution than ever before.
In this study, we focused on two typical solar surface flows, differential rotation and meridional circulation, which are the parameters of the SFT model. We apply a magnetic element tracking (MET) module on the SDO/HMI magnetogram to estimate the solar surface velocities. The polar region is difficult to be observed in the low resolution HMI data. We use the high resolution Hinode/SOT magnetogram to measure the surface motion in the polar region. The alignment of the SOT data was performed in comparison with the HMI data. Because the HMI data is available since 2010, we calculated solar surface flows for the entire period of solar cycle 24. As a result, we obtained the latitudinal profile and time variation of the meridional flow and differential rotation rate. We find that the differential rotation/meridional flow is faster/slower at the latitude where the sunspots frequently emerge, respectively[YM1] . From the Hinode/SOT data, we calculated solar surface flow in the polar region with higher spatio-temporal resolution than ever before.