Caption: Magnetic field on the solar surface and the initial brightening of largest solar flare (GOES class X9.3) in the solar cycle 24 in NOAA Active Region (AR) 12673 on Sep. 6, 2017. They were observed by HMI and AIA onboard the NASA’s Solar Dynamics Observatory (SDO) satellite. A: Magnetic field on the solar surface before the onset of the large flare at 11:45 UT on the day. White and black indicates the intensity of magnetic field along the line of sight out of and toward the plane. B: The zoom-in view of vertical magnetic field in AR 12673. A white circle indicates the location where a large flare was predicted by this study. Black contour shows the magnetic polarity inversion (PIL). C: Bright flare ribbon observed by SDO/AIA1600Å at 11:52 UT. B and C are reformatted based on Fig.3 of this research paper by Kusano et al. (2020) published in Science.

Using the X-ray images taken with the Yohkoh satellite launched in 1991 and operated until 2001, the US Yohkoh team produced an impressive poster showing the variations of the solar corona seen in X-rays (a). The corresponding maps of the magnetic field distribution was produced by the US National Solar Observatory (NSO) using data from the magnetograph at Kitt Peak, Arizona (b). The Solar-Terrestrial Environment Laboratory (STEL, the predecessor of ISEE), Nagoya University, created velocity distribution maps of the solar wind (c).

(a) X-rays

(b) Magnetic field

(c) Solar wind

For the period of 2009-2019 (the 24th Solar Cycle), including the five years of PSTEP, we have produced a new poster with the same design. The X-ray data are from Hinode instead of Yohkoh, and the solar wind data are from the Institute for Space-Earth Environmental Research (ISEE), Nagoya University, as before. The magnetic field and white light data are from National Astronomical Observatory of Japan, at Mitaka, Tokyo. The radio images are by the Nobeyama RadioHeliograph, Nobeyama Solar Radio Observatory of the National Astronomical Observatory of Japan (currently operated by an international consortium led by Nagoya University), and the Hα images are from Hida Observatory, Kyoto University. Please note that all data are made in Japan, including those from international joint projects led by Japan such as Hinode.

Solar Cycle 2009-2019 POSTER Downroad here

Details on data sources

Takashi Sakurai (NAOJ), PSTEP A04 Team

 Explosive phenomena in the solar corona such as solar flares and coronal mass ejections are considered to be processes to liberate free magnetic energy in the corona. In order to clarify and predict these phenomena, information on the three-dimensional distribution of the magnetic field in the corona is required. High-accuracy and high-resolution data of the magnetic field, however, cannot be directly measured except for the vector magnetic field on the photosphere. Thus, various methods for coronal magnetic field reconstruction from the photospheric magnetic field have be investigated.

 Since the plasma pressure is much lower than the magnetic pressure in the corona, we expect that the coronal magnetic field can be approximated by a force-free magnetic field where the Lorentz force is zero. Accordingly, attention has been focused mainly on the development of numerical extrapolation techniques of the force-free field. The photospheric magnetic field, however, is not force-free in general because the effect of the plasma pressure is not negligible compared to that of the magnetic pressure at the photosphere. In addition, the chromospheric magnetic field is affected by gravity too. In this study, we proposed a novel magnetohydrodynamic relaxation method which extrapolates the non-force-free magnetic field in the solar atmosphere including the corona and chromosphere from the photospheric magnetic field. The present method reconstruct a magnetohydrostatic equilibrium magnetic field without using the photospheric density and pressure data which is difficult to measure accurately in particular. A robust numerical solver for the method was developed at the same time.

Let us show the results of preliminary numerical experiments. At the bottom boundary of the model, a force-free magnetic field was imposed in the central region, while the magnetic field in other regions was set to zero. Thus, the central and peripheral regions correspond to active and quiet regions, respectively. The Lorentz force is not zero at interfaces between the active and quiet regions because the magnetic field is discontinuous at the interfaces. The three-dimensional magnetic field was reconstructed using the proposed method as a force-free or non-force-free magnetic field model under this condition. In the force-free field model, artificial lateral expansion of the magnetic field was observed (Figure 1). On the other hand, in the non-force-free field model, the height of the magnetic loop changed depending on the scale height H and thickness Z of the chromosphere (Figures 2 and 3).

Note, by the way, that the numerical experiments are simple but numerically troublesome since the magnetic field at the bottom is discontinuous. We also expect that our numerical solver can be alternative to existing solvers for extrapolating the force-free field.

 Miyoshi, T., Kusano, K., and Inoue, S. (2020), A magnetohydrodynamic relaxation method for non-force-free magnetic field in magnetohydrostatic equilibrium, The Astrophysical Journal Supplement Series, 247:6

DOI: 10.3847/1538-4365/ab64f2
https://iopscience.iop.org/article/10.3847/1538-4365/ab64f2

 
Figure 1:Distribution of the magnetic field for the force-free model. The lines represent the magnetic field lines. The color indicates the out-of-plane magnetic field.

Figure 2:Same as Figure 1, but for the non-force-free model, H≈ 3 > Z ≈ 1.

Figure 3:Same as Figure 1, but for the non-force-free model, H≈ 3 < Z ≈ 4.

LINK: 2020 George Ellery Hale Prize Winner – Kazunari Shibata (AAS/SPD)
URL: https://spd.aas.org/node/71

LINK
The 1st Fumiko Yonezawa Memorial Prize of the Physical Society of Japan
URL: https://www.jps.or.jp/activities/awards/yonezawa/yonezawa1-2020.php

http://www.pstep.jp/news/20200127.html

Project for Solar-Terrestrial Environment Prediction (PSTEP) launched in 2015 in order to improve the synergy between the basic research of solar-terrestrial environment and the forecast operation of space weather and space climate is closing on March 2020. The International Symposium PSTEP-4 and the 2nd ISEE Symposium will be organized to summarize the results of PSTEP and to promote the international research of solar-terrestrial environment prediction. The symposium will consist of invited talks and contributed (oral and poster) presentations for the following topics:

– Operational forecast of space weather
– Prediction of geo-space dynamics
– Prediction of solar storms
– Prediction of the solar cycle and the solar influence on climate

We welcome the participation and presentation of everyone who is interested in any fields related to PSTEP.

Date: January 28 (Tuesday) to 30 (Thursday), 2020

Agenda: Oral Session & Poster Session

Abstracts: https://nuss.nagoya-u.ac.jp/s/zLNDysqj45EtoAS

Shared Folder: https://nuss.nagoya-u.ac.jp/s/RQ5pkmZZtwRaPPo

Instructions for oral presentations:
All speakers are requested to bring their own PC for presentation. The projector is connected to computers via a D-sub 15-pin plug. The aspect ratio of projector screen is 16:9. We recommend checking the connection to the projector before your session starts.

Instructions for poster presentations:
You can display your poster during all three days of the symposium although poster sessions are allocated on January 28 (day 1) and 30 (day 3). The poster size should be smaller than A0 size of 841 mm (width) x 1189 mm (height).

Venue: Sakata Hirata Hall in Nagoya University, Nagoya, Japan

Access to Nagoya University Higashiyama Campus:
http://en.nagoya-u.ac.jp/access/

MAP of Higashiyama Campus:
http://en.nagoya-u.ac.jp/map/

Banquet:
Date & Time: January 29 (Wed) 2020, 19:00-21:00,
Place: AMANDAN TERRACE
https://produce.novarese.jp/amandan-terrace/

PSTEP Special Issue of Earth, Planets and Space (EPS):
Deadline for submissions: April 30, 2020
Expected publication date: December 2020
https://earth-planets-space.springeropen.com/pstep

Science organizing committee:
Kanya Kusano, Mamoru Ishii, Kiyoshi Ichimoto, Yoshizumi Miyoshi, Shigeo Yoden

Local Organizing committee:
Kanya Kusano, Shinsuke Imada, Yoshizumi Miyoshi, Kazuo Shiokawa, Haruhisa Iijima, Yuichi Otsuka, Takafumi Kaneko, Yumi Bamba, Satoshi Inoue, Sung-Hong Park

1st announcement of PSTEP-4:
http://www.pstep.jp/information_en/20191015-2.html
2st announcement of PSTEP-4:
http://www.pstep.jp/news_en/20200114-3.html

Prior symposiums:
-PSTEP-1
http://www.pstep.jp/information/2nd-circular-1st-pstep-international-symposium.html
-PSTEP-2
http://www.pstep.jp/information/20170314.html
-PSTEP-3
http://www.pstep.jp/information/20180226.html

Organizer/Host:
– Project for Solar-Terrestrial Environmental Prediction (PSTEP)
– Institute for Space-Earth Environmental Research (ISEE), Nagoya University

Contact:
isee@pstep.jp

Solar eruptive phenomena, such as flares and coronal mass ejections (CMEs), generate high-energy particles called solar energetic particles. Severe SEP events sometimes cause satellite anomalies and radiation exposure to humans in space. Understanding and forecasting SEPs is an important issue in space weather. We investigated SEPs in the Coordinated Data Analysis Workshop for SEPs organized by PSTEP on 2017 (PSTEP-SEP-CDAW https://sites.google.com/view/pstep-cdaw/home?authuser=0″ ).
We investigated the relationship between the spectral structures of type II solar radio bursts in the hectometric and kilometric wavelength ranges and the peak flux of SEPs. To examine the statistical relationship between type II bursts and SEPs, we selected 26 CME events with similar characteristics (e.g., initial speed, angular width, and location) observed by the Large Angle and Spectrometric Coronagraph (LASCO), regardless of the characteristics of the corresponding type II bursts and the SEP flux. Then, we compared associated type II bursts observed by the Radio and Plasma Wave Experiment (WAVES) onboard the Wind spacecraft and the SEP flux observed by the Geostationary Operational Environmental Satellite (GOES) orbiting around the Earth. We found that the bandwidth of the hectometric type II bursts and the peak flux of the SEPs has a positive correlation (with a correlation coefficient of 0.64). This result supports the idea that the nonthermal electrons of type II bursts and the nonthermal ions of SEPs are generated by the same shock and suggests that more SEPs may be generated for a wider or stronger CME shock with a longer duration. Our result also suggests that considering the spectral structures of type II bursts can improve the forecasting accuracy for the peak flux of gradual SEPs.

Reference
Kazumasa Iwai, Seiji Yashiro, Nariaki V. Nitta, and Yûki Kubo
“Spectral Structures of Type II Solar Radio Bursts and Solar Energetic Particles”
The Astrophysical Journal, 888:50
https://doi.org/10.3847/1538-4357/ab57ff

Figure 1: Radio dynamic spectra of type II bursts observed on 2006 December 13.

Figure 2: Scatter plots of the peak flux of SEPs and the bandwidth of hectometric type II bursts.

Project for Solar-Terrestrial Environment Prediction (PSTEP) launched in 2015 in order to improve the synergy between the basic research of solar-terrestrial environment and the forecast operation of space weather and space climate is closing on March 2020. The International Symposium PSTEP-4 and the 2nd ISEE Symposium will be organized to summarize the results of PSTEP and to promote the international research of solar-terrestrial environment prediction. The symposium will consist of invited talks and contributed (oral and poster) presentations for the following topics:

– Operational forecast of space weather
– Prediction of geo-space dynamics
– Prediction of solar storms
– Prediction of the solar cycle and the solar influence on climate

We welcome the participation and presentation of everyone who is interested in any fields related to PSTEP.

Date: January 28 (Tuesday) to 30 (Thursday), 2020

Agenda: Oral Session & Poster Session

Venue: Sakata Hirata Hall in Nagoya University, Nagoya, Japan

Access to Nagoya University Higashiyama Campus:
http://en.nagoya-u.ac.jp/access/

MAP of Higashiyama Campus:
http://en.nagoya-u.ac.jp/map/

Instructions for poster presentations:
You can display your poster during all three days of the symposium although poster sessions are allocated on January 28 (day 1) and 30 (day 3). The poster size should be smaller than A0 size of 841 mm (width) x 1189 mm (height).

Instructions for oral presentations:
All speakers are requested to bring their own PC for presentation. The projector is connected to computers via a D-sub 15-pin plug. The aspect ratio of projector screen is 16:9. We recommend checking the connection to the projector before your session starts.

Contact:
isee@pstep.jp

Science organizing committee:
Kanya Kusano, Mamoru Ishii, Kiyoshi Ichimoto, Yoshizumi Miyoshi, Shigeo Yoden

Local Organizing committee:
Kanya Kusano, Shinsuke Imada, Yoshizumi Miyoshi, Kazuo Shiokawa, Haruhisa Iijima, Yuichi Otsuka, Takafumi Kaneko, Yumi Bamba, Satoshi Inoue, Sung-Hong Park

1st announcement of PSTEP-4:
http://www.pstep.jp/information_en/20191015-2.html

Prior symposiums:
-PSTEP-1
http://www.pstep.jp/information/2nd-circular-1st-pstep-international-symposium.html
-PSTEP-2
http://www.pstep.jp/information/20170314.html
-PSTEP-3
http://www.pstep.jp/information/20180226.html

Organizer/Host:
– Project for Solar-Terrestrial Environmental Prediction (PSTEP)
– Institute for Space-Earth Environmental Research (ISEE), Nagoya University

Strong solar flares, which sometimes cause geomagnetic storms and aurorae, are known to emanate from complex-shaped sunspot regions. However, because the solar interior is inaccessible with optical observations, it has been unclear how subsurface magnetic flux emerges to the surface and produces such flare-productive sunspots. Although a multitude of numerical simulations that mimic the flux emergence from the interior have been conducted, most of them are highly idealized models in which the flux is arbitrarily endowed with complexity or forcibly injected into the computational domain. In this study, by utilizing state-of-the-art numerical code R2D2, we succeeded in the first-ever modeling of the convection-driven flux emergence and the resultant spontaneous generation of flare-productive sunspots.

One of the characteristics of R2D2 is that it can simultaneously solve a wide spectrum of thermal convection from the granular cells of 1000 km in size and 10 minutes in lifetime that reside in the solar surface to the 100,000 km-sized, one-month-life cells in the deep convection zone in a single computational domain. Here we study the process that a magnetic flux placed in the solar interior is elevated by this realistic thermal convection. As a result, large-scale convective upflows raise the flux to the surface at two sections and strongly-packed sunspots called the “delta-spots” are eventually generated (Figures 1 and 2). Delta-spots may produce great flares of X10 class or higher. The present simulation suggests that the generation of delta-spots, and therefore the resultant flare eruptions, are a stochastically determined process that depends on the interaction between magnetic flux and background turbulent convection within the solar interior.

Figure 1: Generation of flare-productive sunspots. From left to right, the emergent intensity, magnetic field strength (white and black indicate positive and negative polarities, respectively), and field strength on the vertical cross-section at the times of 32 hours and 42 hours. The positive and negative sunspots collide against each other and create “delta-spots”, in which umbrae of both polarities are surrounded by a common penumbra.

Figure 2: Strongly twisted magnetic field lines are created in the atmosphere above the delta-spots. This structure is called a magnetic flux rope, which is ejected into the interplanetary space once a flare eruption occurs.

S. Toriumi and H. Hotta, “Spontaneous Generation of δ-sunspots in Convective Magnetohydrodynamic Simulation of Magnetic Flux Emergence”, The Astrophysical Journal Letters, 886, L1, 2019
https://iopscience.iop.org/article/10.3847/2041-8213/ab55e7
Also refer to PSTEP Science Nugget No.19 for the R2D2 code and Science Nugget No.4 for the delta-sunspots.