Session 13 - Critical challenges and recent advances in the reliable forecast of solar activity and extreme space weather events

Elena Popova, Michael Balikhin (University of Sheffield, UK)
Friday 9/11, 09:00-10:30
MTC 01.03

Significant progress in the development of various tools to forecast the space weather parameters in the near geospace resulted from FP6, FP7, HORIZON2020 and other international/national programmes. The advance in our understanding of dynamical processes, in the near geospace based on about 60 years of in situ observations by vast number of spacecraft missions. However, one of the critical unsolved problems is the forecast of extreme space weather events with a short transit time from the Sun to L1. Prediction of such extreme events with necessary advanced time requires the forecast of solar activity. While powerful techniques that involve machine learning and systems science methodologies are indispensable in the development of accurate forecasting tools, the advance of our physical understanding about processes that occur at the Sun is also critical to develop the reliable forecast in particular for very rare extreme events. One of the great challenges is that while plentiful of remote observations of the solar processes are available, this is not the case for situ measurements that were so vital for the development of our understanding of how the magnetosphere works.

The current session is devoted to the review of recent advances in the forecasting of solar activity and understanding of dynamical processes at the Sun and to the discussion of key unsolved problems in both data based and first principles based approaches to study our nearest star, that should be resolved in order to develop the reliable forecast of extreme events.

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Talks : Time schedule

Friday November 9, 09:00 - 10:30, MTC 01.03

09:00	The Great August 1972 Heliospheric Disturbance—What We Know Now	Knipp, D et al.	Invited Oral
	Delores Knipp[1], Brian Fraser[2], Margaret Shea[3], Don Smart[4]
	[1] University of Colorado, [2] University of Newcastle, [3] Retired, [4] Retired
	The Great August 1972 Heliospheric Disturbance—What We Know Now The solar events of early August 1972 were record-breaking for almost every type of heliospheric disturbance, except, for the Disturbance Storm Time (Dst) index. The Sun-Earth transit time of the 4 August Coronal Mass Ejection (CME) was less than 15 hours. The shock-driving CME pushed the magnetosphere to within 5 RE. Rapid ground magnetic perturbations rivaled those of the modern era. I will review the solar and geophysical records of this event and explain why this storm was far more “Carrington-like” than most modern researchers recognize, despite its apparently lack-luster magnetospheric disturbance index. The events of early September 2017 provide a gentler analogue case that allows us to extract lessons learned from a milder set of heliospheric disturbances in a well-instrumented epoch.
09:15	Towards Improved Operational Space Weather Forecasts – challenges in modelling and observations	Jackson, D et al.	Invited Oral
	David Jackson
	Met Office, UK
	A strategic research goal at the Met Office is to develop operational space weather forecasts based on a coupled Sun to Earth modelling system. The models would ideally be physics-based, be constrained by data assimilation and undergo regular verification. In reality, we are still far away from this goal: a coupled system has not yet been implemented, data assimilation systems only exist for parts of the Sun to Earth domain, and a lack of understanding of physical processes mean that the use of empirical models in preference to physics-based models remains commonplace. In this presentation, the gaps in this ideal future Sun to Earth system are analysed. As well as producing a list of scientific and technical challenges that will need to be met, I will give examples of ways in which the Met Office is beginning to address the problems. Examples will include a data assimilation system for the heliosphere and the development of a whole atmosphere model which will enable coupling between the ionosphere, the thermosphere and the lower atmosphere. The operational models also need to be constrained by assimilation of observations in order to ensure the model initial conditions (and thus their forecasts) are as accurate as possible. However, many parts of the space weather domain are poorly observed. The World Meteorological Organization (WMO) has identified requirements for operational space weather observations and has also analysed the gaps in the existing network. This can be applied to ensure the observation network develops in a methodical way. This approach has helped guide the design for new operational solar / heliosphere missions to L5 and L1, for which there is now an extremely strong and urgent case. I will also indicate how the WMO requirements can be used in the design of a new observation network for the thermosphere.
09:30	Forecasting Extreme Space Weather in Earth’s Magnetosphere: Challenges and Opportunities	Singer, H et al.	Invited Oral
	Howard J. Singer[1], Michele Cash[1], Christopher Balch[1], Rob Steenburgh[1], George Millward[2], Eric Adamson[2], Gabor Toth[3], Daniel Welling[3]
	[1] NOAA Space Weather Prediction Center, [2] University of Colorado, Cooperative Institute for Research in Environmental Sciences (CIRES), [3] University of Michigan, Climate and Space Sciences and Engineering
	The effects of extreme space weather on technology have been documented on numerous occasions, ever since the well-known Carrington event in 1859. More recently, studies have been carried out to consider the societal and economic impact of such events. The results of these studies as expressed, for example, in the U.S. National Space Weather Strategy and Action Plans, demonstrate the need for improved forecasts of extreme space weather. In response to these needs, the National Oceanic and Atmospheric Administration (NOAA), in coordination and partnership with scientists, other agencies, the commercial sector and the international community, has invested in new capabilities to predict severe space weather conditions. In this presentation, we will describe ongoing work at NOAA’s Space Weather Prediction Center for utilizing new observations and models to better forecast space weather conditions. We will focus on the recent large-scale numerical models that have been transitioned into operations, including the Wang-Sheeley-Arge-Enlil cone model for predicting the background solar wind and coronal mass ejection (CME) arrival and on the University of Michigan’s Geospace model for predicting regional geomagnetic activity and other disturbances in near-Earth space and on the ground. While the Geospace model is driven by solar wind conditions measured at L1, upstream of Earth, we will discuss the challenges and opportunities for providing longer lead time predictions by utilizing solar observations, and models with input starting at the sun. Finally, we will describe new opportunities and capabilities that are envisioned for the more effective transfer of models and data into operational use.
09:45	UNIVERSAT-SOCRATES project and complementary cubsat missions for monitoring of space hazards	Svertilov, S et al.	Oral
	M. Panasyuk[1,2], A. Iudin[1], V. Kalegaev[1], P. Klimov[1], S. Svertilov[1,2], O. Ploc[3], G. Reitz[3], I. Ambrožová[3], M. Kákona[3], I. Kolmašová[3], P. Kovář[3], V. Bogomolov[1,2], V. Osedlo[1], V. Petrov[1], M. Podzolko[1], E. Popova[1,4], I.V. Yashin[1], M. Bartelemy[5], T. Sequies[5], E. Roland[5]
	[1] Moscow State University, Skobeltsyn Institute of Nuclear Physics, Moscow, Russia, [2] Moscow State University, Physical Department, Moscow, Russia, [3]Nuclear Physics Institute of the CAS, Department of Radiation Dosimetry, Praha, Czech Republic, [4] The Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences, Moscow, Russia, [5] University Grenoble Alpes, Grenoble, France.
	D. V. Skobeltsyn Institute of Nuclear Physics of M. V. Lomonosov Moscow State University (SINP MSU) is developing the new project “UNIVERSAT-Socrat” intended for monitoring of space factors being a threats space missions: ionizing space radiation, electromagnetic transient luminous events in the atmosphere, asteroids and space debris, and powerful gamma ray bursts in space. A system of small satellites will be launched into specially selected orbits crossing the wide range of magnetic drift shells at different altitudes. The primary scope for the project is the operational monitoring of near-Earth’s radiation environment: fluxes of electrons and protons of Earth’s radiation belts and energetic particles of solar galactic origin. Detection of ionizing radiation generated by an atmospheric discharge or electromagnetic transient luminous events produced by a secondary energetic particle is a further important task of this project related to particle fluxes dynamics; strong variations of the fluxes are observed. The energetic particles are responsible for an enhanced radiation exposure, ionization effects, internal charging, single event effects and other hazards that can prevent human activity in spacecraft altitudes as well as in the upper and lower atmosphere and on-ground. These space factors also represent a significant health risk for manned spacecraft crew and passengers onboard aircraft. Data on energetic particle fluxes measured on-board satellites from UNIVERSAT-Socrat constellation will be evaluated together with the Research Center of Cosmic Rays and Radiation Events in the Atmosphere (CRREAT project developed by the Nuclear Physics Institute of the CAS, Institute of Atmospheric Physics of the CAS and the Faculty of Electrical Engineering of the Czech Technical University in Prague) in order to study the relation between atmospheric phenomena and ionizing radiation. The studies may contribute to the question whether the ionizing radiation generated by an atmospheric discharge or lightning generation can be triggered by a secondary cosmic particle shower. Joint activity in terms of UNIVERSAT-Socrat and CRREAT projects can address so far unanswered questions of detection and dosimetry of ionizing radiation both of cosmic and terrestrial origin and will contribute to the improvement of space weather models, air transport safety measures and global navigation systems reliability.
10:00	The development of a real time Dst Index forecast model	Boynton, R et al.	Oral
	Richard Boynton[1], Hua-Liang Wei[1], Simon Walker[1]
	[1] ACSE, University of Sheffield
	A set of data based models are trialed to develop a real time model of the Dst index. The methodologies used to deduce these models are based on Nonlinear AutoRegressive Moving Average eXogenous (NARMAX). These methods automatically deduce reliable and accurate forecast models of complex dynamical systems with unknown physics. NARMAX models are built up term by term in a way that reveals the contribution of each input parameter, which makes the models physically interpretable as apposed to Neural Networks, where the input terms are linked to the output through a maze of neurons. This is an essential advantage, as we require not only an accurate forecast model but also seek to understand the physics behind the model. Three algorithms are employed to deduce the Dst index models using the same inputs and training data and the performance results are compared. A model is then selected and implemented in real time to provide online forecasts.
10:15	Solar cycle prediction and phase synchronization of solar dynamo	Shapoval, A et al.	Oral
	Alexander Shapoval[1], Elena Blanter[2,1], Jean-Louis Le Mouël[3], Mikhail Shnirman[2,1], Vincent Courtillot[3]
	[1]National Research University Higher School of Economics, [2]Institute of Earthquake Prediction Theory Russian Academy of Sciences, [3]Institute de Physique du Globe, Paris
	Prediction of solar activity is an essential part of the Space Weather forecast. Comparisons of the predictions of the Solar Cycle 24 show that the best quality is given by the forecast based on the polar field (Pesnell, 2016). Geomagnetic precursors are found to be most reliable for the solar cycle 22 (Layden et al, 1991). Recent models provide an explanation of the forecasting success of the geomagnetic and polar field precursors in the solar dynamo. We consider the evolution of phase synchronization between the solar activity and the polar magnetic field as the origin of successful prediction and eventual fails of solar activity forecasts. We successfully apply the Kuramoto model of nonlinear coupled oscillators to the description of the phase synchronization between the sunspot activity and the polar field in two solar hemispheres. We find that the evolution of phase synchronization of the solar field corresponds to a weakly coupled oscillatory system, which explains spontaneous breaks of synchronization and irregular solar cycles. The irregularity of solar cycle 20 is related to a phase catastrophe in the polar field evolution, which leads to the anomalous phase de-synchronization between the solar activity and the polar field also reflected in geomagnetic indices. Solving an inverse problem in the Kuramoto model, we are able to reconstruct the evolution of the meridional flow rotation speed. We show that the beginning of the atypical solar cycle 24 is related to a significant fall of the meridional flow speed. The meridional circulation is closely related to the polar field generation and therefore is better reflected by the polar field precursors. We consider the hemispheric asymmetry of the reconstructed meridional flow speed and find two changes of the leading hemisphere: in the 1920s and in the 1950s. The last change corresponds to the solar cycle 19 and may be the origin of the increased variability of the solar activity forecasts and fail of certain precursors. The change in the North-South asymmetry of the meridional circulation speed recorded in 1950 precedes the phase catastrophe of solar cycle 20, thus supporting the significance of the hemispheric asymmetry for the long-term prediction of solar activity. We suggest that studies of the phase synchronization between solar indices have a strong potential for the understanding of solar dynamo and space weather forecasting. E. Blanter, A. Shapoval, and M. Shnirman acknowledge the support of the Russian Science Foundation through project No 17-11-01052.

Posters

1	Predicting the Where and the How Big of Solar Flares	Leka, K et al.	p-Poster
	KD Leka[1, 2], G Barnes[1], S Gilchrist[1]
	[1] NWRA, [2] Nagoya University / ISEE
	The approach to predicting solar flares generally characterizes global properties of a solar active region, for example the total magnetic flux or the total length of a sheared magnetic neutral line, and compares new data (from which to make a prediction) to similar observations of active regions and their associated propensity for flare production. We take here a different approach, examining solar active regions in the context of their energy storage capacity. Specifically, we characterize not the region as a whole, but summarize the energy-release prospects of different sub-regions, using a sub-area analysis of the photospheric boundary, non-linear force-free modeling of particular current systems, and the "Minimum Current Corona" model. We present here early results from this approach whose objective is to understand the different pathways available for regions to release stored energy, thus eventually providing better estimates of the "where" (what sub-areas are storing how much energy) and the "how big" (how much energy is stored, and how much is available for release) of solar flares -- the latter being relevant to predicting the possibility of large vs. extreme events.
2	Inferring longitudinal magnetic flux distributions from EUV images	Ireland, J et al.	p-Poster
	Jack Ireland[1], Laura Boucheron[2], R. T. James McAteer[2]
	[1] ADNET Systems, Inc. / NASA GSFC, [2] New Mexico State University, NM, USA.
	The photospheric magnetic flux of the far side of the Sun is vital in understanding the global connectivity of the Sun’s magnetic field. Unfortunately, there are no magnetographs that image the far side of the Sun. Presence and size estimates of active regions on the far side can be inferred from helioseismological observations on the near side of the disk. However, the magnetic structure, crucial to understanding the overall global magnetic field, is not well understood from these estimates. Although we do not have magnetographs imaging the far side of the Sun, the STEREO mission does have EUV imagers that image structures that arise from the underlying magnetic flux that penetrates the photosphere. It is well known that the total EUV flux is correlated to the total line-of-sight magnetic flux in active regions. Thus, total line-of-sight magnetic flux can be estimated from total EUV flux, but the magnetic flux distribution cannot. The recent development of fully convolutional neural networks (FCNN) has made it possible to output images (multi-dimensional output) rather than simple classification labels (scalar or vector output) from input images. This introduces the possibility of mapping between simultaneously observed images in different modalities, such as magnetograms and EUV emission. We present some exploratory work testing the feasibility of this approach to determining longitudinal magnetic flux distributions from EUV emission through training a FCNN on AIA data. We also discuss various systematic effects in the data that must be considered in order to provide a consistent and usable training data set. The extension of this study to using STEREO farside EUV images to infer farside magnetic field distribution is also discussed.
3	Radiation Monitoring and Space Weather Research in Russian – Azerbaijan Small Satellite Project.	Popova, E et al.	p-Poster
	M.I. Panasyuk[1], P. Abdullaev[2], G. Agaev[2], V.V. Bogomolov[1], A.F.Iyudin[1], R. Gasanov[2], V.V. Kalegaev[1], S.V. Krasnopeev[3], T. Mamedzade[4], V.I. Osedlo[1], A.P. Papkov[3], V.L. Petrov[1], M.V. Podzolko[1], E.P. Popova[1,5], A. Proskuryakov[2], R. Rustamov[4], A.S. ogly Samedov[2], H. Seyidov[2], S.I. Svertilov[1], I.V. Yashin[1]
	[1] M.V. Lomonosov Moscow State University, Moscow , Russia [2] Azerbaijan National Aviation Academy, Baku, Azerbaijan [3]Air and Space Technique Research Laboratory, Kaluga, Russia [4] Azercosmos, Baku, Azerbaijan [5] The Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences, Moscow, Russia
	Small satellites are very appropriate for study different physical phenomena, which can be dangerous for spacecraft technique and biological objects. The transient electromagnetic events, such as Terrestrial Gamma Ray Flashes (TGF), Transient Luminous Events (TLE) and cosmic Gamma Ray Bursts (GRB) as well as magnetosphere electron flux dynamics are very important factors of natural hazards in the near-Earth space. These phenomena will be observed during the space experiment with number of instruments on board small satellite elaborated together by M,V, Lomonosov State University and Azerbaijan National Aviation Academy. The solar-synchronous orbit with relatively low altitude (50-800 km) provides the favourable conditions for the study of space radiation in different areas of the near-Erath space including as trapped radiation as electron precipitation from the radiation belts. It will be presented the development of conceptual scientific and functional bases of the small satellite experiment for study of the medium-term and long-term dynamics of the spatial distribution of the energetic charged particle fluxes in a large areas of the Earth's radiation belts for space weather forecast. This goal involves the elaboration of a general scientific concept of satellite experiment, determination of optimal orbits and orientation of spacecraft, determination of parameters and technical appearance of measuring instruments (spectrometers of energetic protons and electrons), requirements for satellite platform, orientation system, data transmission, ground data processing center, mathematical modeling of the experiment. The measurement data, which are planned to be obtained during this experiment, will be subsequently used for the following scientific and applied tasks: - studying the processes of acceleration and loss of trapped and quasi-trapped energetic charged particles in the Earth's magnetosphere; - validation of existing and development of new dynamic models of Earth's radiation belts; - support and ensure the safety of the functioning of space vehicles.
4	Regular and stochastic constituents of solar magnetic activity: theory and observations.	Popova, E et al.	p-Poster
	Elena Popova
	The Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences, Moscow, Russia, M.V. Lomonosov Moscow State University, Moscow , Russia
	Solar magnetic activity is associated with the generation of strong magnetic fields in the solar convective zone and has complicated structure. The most famous cycle is the nearly periodic 11-year change in number of sunspots and changes in the levels of solar radiation and ejection of solar material. Sunspots numbers over the past 11,400 years have been reconstructed using Carbon-14-based dendroclimatology. On the basis of this and other data, it was found that there are a large number of cycles with characteristic time scales of 2, 22, 87, 210, 2300 and 6000 years. the key word to describe it would be variability, almost randomness. In this paper we model the variety of periods of solar magnetic activity with the help of dynamic systems based on the nonlinear alpha-omega dynamo.
5	Experiment on GRB and TGF Study in Russian – Azerbaijan Small Satellite Project.	Popova, E et al.	p-Poster
	M.I. Panasyuk[1], P. Abdullaev[2], G. Agaev[2], V.V. Bogomolov[1], A.F. Iyudin[1], R. Gasanov[2], V.V. Kalegaev[1], S.V. Krasnopeev[3], T. Mamedzade[4], V.I. Osedlo[1], A.P. Papkov[3], V.L. Petrov[1], M.V. Podzolko[1], E.P. Popova[1,5], A. Proskuryakov[2], R. Rustamov[4], A.S. ogly Samedov[2], H. Seyidov[2], S.I. Svertilov[1], I.V. Yashin[1]
	[1] M.V. Lomonosov Moscow State University, Moscow , Russia [2] Azerbaijan National Aviation Academy, Baku, Azerbaijan [3]Air and Space Technique Research Laboratory, Kaluga, Russia [4] Azercosmos, Baku, Azerbaijan [5] The Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences, Moscow, Russia
	Small satellites are very appropriate for study different physical phenomena, which can be dangerous for spacecraft technique and biological objects. The transient electromagnetic events, such as Terrestrial Gamma Ray Flashes (TGF), Transient Luminous Events (TLE) and cosmic Gamma Ray Bursts (GRB) as well as magnetosphere electron flux dynamics are very important factors of natural hazards in the near-Earth space. These phenomena will be observed during the space experiment with number of instruments on board small satellite elaborated together by M.V. Lomonosov State University and Azerbaijan National Aviation Academy. The solar-synchronous orbit with relatively low altitude (50-800 km) provides the favourable conditions for the study of different burst phenomena, such as Terrestrial Gamma Ray Flashes (TGRFs) from different areas of the Earth Atmosphere including near equatorial and polar regions as well as and cosmic Gamma Ray Bursts (GRBs). Study of GRBs and TGRFs still remains very important despite a lot of data obtained about such phenomena in recent time. The main reason is the absence of sufficiently complete theoretical understating of physical nature of high energy processes in the Earth atmosphere as well as the complete model of GRB. As it seems, the complex observations in different electromagnetic wave bands with good accuracy of event source localization are necessary. Advanced instruments for observations of TGRFs as well as for monitoring of GRBs with are presented.
6	Planetary triggering and statistical forecasting of extreme events	Petrakou, E et al.	p-Poster
	Eleni Petrakou
	independent
	In a recent work[*] a model was demonstrated for forecasting the solar cycle evolution in terms of flares, based on the apparent coupling between an internal component and the relative motion of planets Jupiter and Saturn. Here we present both that long-timescale model and its extension to short-timescales, i.e. the forecasting of dates of extreme events. More specifically, associations are presented between the motion of inner and outer planets and a number of solar observables, and the extraction of statistical rules that seem fit for prediction of strong events is demonstrated. This apparent triggering of solar activity could be used to compliment the space weather modeling chain. Moreover, some possible mechanisms are touched upon, as further expansion of the study is expected to result in first-principles prediction. [*] https://www.sciencedirect.com/science/article/pii/S136468261830004X
7	Studying stealth CMEs using advanced imaging analysis techniques	O'kane, J et al.	p-Poster
	Jennifer O’Kane[1], Lucie Green[2], David Long[3]
	[1]Mullard Space Science Laboratory, UCL,[2]Mullard Space Science Laboratory, UCL,[3]Mullard Space Science Laboratory, UCL
	Stealth coronal mass ejections (CMEs) are eruptions from the Sun that have no obvious low coronal signature. These CMEs are characteristically slower events, but can still be geoeffective and affect the space weather at Earth. Therefore understanding the science underpinning these eruptions will greatly improve our ability to detect and, eventually, predict them. We present a study of several stealth CMEs analysed using new advanced techniques that reveal their faint signatures in observations from the EUV imagers onboard the SDO and STEREO spacecraft. The different viewpoints of the events given by these spacecraft provide the opportunity to study the eruption from above and the side contemporaneously. For each event, we combined the AIA observations with potential field modelling to reveal the coronal structure that erupted and measured the kinematics of the eruption. We discuss the physical processes that occurred in the time leading up to the onset of each CME and comment on whether these eruptions are the low-energy and velocity tail of the distribution of CME events or whether they are a distinct phenomenon.
8	Statistical approaches for the forecast of the F10.7 index	Podladchikova, E et al.	p-Poster
	Olena Podladchikova, Christophe Marque and SIDC forecasting team
	Royal Observatory of Belgium
	Solar radio flux measurements at 10.7 cm provide a reliable monitoring dataset of the solar activity over the past six solar cycles. The radiation at 10.7 cm is coming from the upper chromospheric/low coronal layers of the Sun, and it is correlated with white light, sunspot number and UV radiation which impacts terrestrial atmospheric layers from the ionosphere till the stratosphere. The statistically analysis of F10.7 index data set is very robust due to the nature of the ground based measurements which are practically unaffected by the weather conditions. Slow modulations of highly non-stationary F10.7 index data series have strong impact on the terrestrial climate, while fast changes - related to energetic solar events - have immediate impact on high frequency communications and on the satellite drag effect, which is significant for small size satellites. In this work, we discuss and update 3 different approaches for the forecast of F10.7 index: 1. SASFF (Self-Adjusted Solar Flux Forecasting) algorithm: the radioflux is described by a non-stationary random walk model with variable drift and the forecast is performed using an adaptive Kalman Filter. 2. Random walk model with and unknown drift and also unknown variance.  The choice of the random walk model is justified by a very weak autocorrelation of the radioflux increment. Uncertainty of the model parameters (drift, variance) is evaluated dynamically and applied for the next forecasting step. 3. Linear regression which considers dependences of the F10.7 index to other solar indices (e.g sunspot number). Considering the fact that constant coefficients cannot reflect non-stationary radioflux behaviour, we correct the regression coefficients during observations using an adaptive Kalman Filter technique.