Which Component of Solar Magnetic Field Drives the Evolution of Interplanetary Magnetic Field over Solar Cycle?

The solar magnetic structure changes over the solar cycle. It has a dipole structure during solar minimum, where the open flux extends mainly from the polar regions into the interplanetary space. During maximum, a complex structure is formed with low-latitude active regions and weakened polar fields, resulting in spread open field regions. However, the components of the solar magnetic field that is responsible for long-term variations in the interplanetary magnetic field (IMF) are not clear, and the IMF strength estimated based on the solar magnetic field is known to be underestimated by a factor of 3 to 4 against the actual in-situ observations (the open flux problem). To this end, we decomposed the coronal magnetic field into the components of the spherical harmonic function of degree and order $(\ell, m)$ using the potential field source surface model with synoptic maps from SDO/HMI for 2010 to 2021. As a result, we found that the IMF rapidly increased in December 2014 (seven months after the solar maximum), which coincided with the increase in the equatorial dipole, $(\ell, m)=(1, \pm1)$, corresponding to the diffusion of active regions toward the poles and in the longitudinal direction. The IMF gradually decreased until December 2019 (solar minimum) and its variation corresponded to that of the non-dipole component $\ell\geq2$. Our results suggest that the understanding of the open flux problem may be improved by focusing on the equatorial dipole and the non-dipole component and that the influence of the polar magnetic field is less significant.Comment: 19 pages, 9 figures, accepted for publication in Ap

Reconstruction method of local density fluctuation for heavy ion beam probe measurements

Heavy ion beam probe (HIBP) is an excellent diagnostic to measure the density and potential fluctuations simultaneously in magnetically confined plasmas. However, it has been well known that the density fluctuation measured with the HIBP is not local but contains the fluctuations along the beam orbits. In this article, a method is proposed to evaluate local density fluctuation in the HIBP measurements by removing the well-known path integral effects. The reconstructed density fluctuation amplitude and power spectrum are shown, for example, by applying the proposed method on the density fluctuation measurement data obtained in a toroidal helical plasma, Compact Helical System

Simultaneous measurements of density and potential fluctuation with heavy ion beam probe in the Compact Helical System

Density and potential fluctuations are simultaneously measured, using a heavy ion beam probe, in electron cyclotron resonance heated plasmas of the Compact Helical System. The spectra of density and potential fluctuations are presented with radial profiles of these fluctuation amplitudes. Local density fluctuations are evaluated by removing the path integral effect under the simplest assumption that the correlation length of the fluctuations is infinitesimally short

Genetic Factors Associated with Heading Responses Revealed by Field Evaluation of 274 Barley Accessions for 20 Seasons

Heading time is a key trait in cereals affecting the maturation period for optimal grain filling before harvest. Here, we aimed to understand the factors controlling heading time in barley (Hordeum vulgare). We characterized a set of 274 barley accessions collected worldwide by planting them for 20 seasons under different environmental conditions at the same location in Kurashiki, Japan. We examined interactions among accessions, known genetic factors, and an environmental factor to determine the factors controlling heading response. Locally adapted accessions have been selected for genetic factors that stabilize heading responses appropriate for barley cultivation, and these accessions show stable heading responses even under varying environmental conditions. We identified vernalization requirement and PPD-H1 haplotype as major stabilizing mechanisms of the heading response for regional adaptation in Kurashiki

Measurement of 3-D Mode Structure of the Edge Harmonic Oscillations in CHS using Beam Emission Spectroscopy

The 3-D spatial structure - radial locality and poloidal/toroidal mode numbers - of the magnetohydrodynamic fluctuation called “edge harmonic oscillation (EHO)” in the compact helical system (CHS) was investigated using beam emission spectroscopy (BES) as the diagnostic method of the local density fluctuations and the magnetic probe array. We found two groups of harmonic oscillations in CHS, one with a frequency of 4.0 kHz and a harmonic located in the edge region of the normalized minor radius ρ = 0.95 near the rotational transform ι = 1 surface, and the other with a frequency of 3.5 kHz and a harmonic located in the core region ρ = 0.53 near the ι = 0.5 surface. The magnetic probe signals showed that the poloidal/toroidal mode numbers of the edge mode and the core mode were -1/1 and -2/1, respectively. They were consistent with the rotational transform of the magnetic field at the locations of those modes