The study on The active sun and its effects on space and Earth climate
has been financed by the Italian MIUR through a PRIN grant for the period 2013-2016, and will address some of the main issues concerning the nature of the variability of solar activity, including the effects on Space Weather and Earth’s climate through the analysis of data obtained from ground-based and space observatories, through the construction of theoretical models, and through direct numerical simulations of the basic physical processes.
The team is composed by researchers from six institutions, all involved in the study of complex heliospheric physical processes, starting from those occurring at the base of the convective region of the Sun up to the corona, as well as in the study of the solar wind and its interaction with the Earth’s magnetosphere. Moreover, the fluctuations of the dynamical conditions and magnetic properties of the Sun and heliosphere at all the spatial and temporal scales modulate the solar activity giving rise to impulsive processes (flares, coronal mass ejections, solar energetic particles) that have an effect on Space Weather, on the magnetosphere and Earth’s climate. The general objective of the project is to achieve a significant improvement in the global knowledge of the complex Sun-Earth system, which allows to connect different solar, heliospheric and magnetospheric processes. To this purpose, the expertise and collaboration within the team on data analysis, experimental aspects, modelling and numerical simulations will result of fundamental importance.
KEY SCIENTIFIC GOALS FOR THE PROJECT:
a) to provide a unified framework in which the techniques of observation of photospheric, chromospheric and coronal magnetic fields allow the investigation of the spatio-temporal properties of these highly dynamic environments as well as of the building blocks of active regions. To this aim, we plan to exploit the spectro-polarimetric available dataset (Hinode, SDO, COMP@MAUNA LOA) and planned observations (IBIS-ROSA-FIRS @ DST, CLASP@JAXA), focusing on the innovative techniques that allow, for the first time, to observe these processes at spatial and temporal scales precluded until a few years ago.
b) to use the results of these new observations as input for modeling processes that occur on the surface of the Sun, related to the variation of the total and spectral solar irradiance and acceleration processes of the solar wind, to the evolution of the active regions and to the generation of explosive processes such as the sudden release of coronal mass, flares and solar energetic particles.
c) to study the transport of particles, plasmas and magnetic field through the heliosphere and their interaction with the magnetosphere of the Earth; to estimate theinput parameters necessary for the development of models for the magnetospheric response to the perturbations, produced on the Sun and by the solar wind, which might affect space and ground-based infrastructures; to investigate the Earth’s climate response potentially induced by changes in spectral solar irradiance and energetic particle flux.
In particular, the main scientific objectives are:
1. Estimate the parameters describing the structure of solar magnetic field and its connection with the solar dynamo and photospheric plasma motion. Characterize the topological complexity of magnetic field structures and pattern in the solar atmosphere and investigate the role of the topology in the dynamics of the emerging structures propagating into the heliosphere.
The spatio-temporal dynamics of generation of the magnetic field, through the dynamo effect in the convective region, induce fluctuations in the magnetic configurations of the active regions in the different layers of the solar atmosphere. The analysis of high resolution magnetograms acquired by ground based and space observatory will provide new insights in the several questions concerning how active regions form and evolve. The role of the magnetic torsion and magnetic helicity variations in the triggering of impulsive events in the solar atmosphere and the role played by the moving magnetic features in the process of decay and diffusion of magnetic fields will be also studied. The results will be compared with the most recent models to identify the most appropriate one for an effective description of the evolutionary stages of active regions.
2. Estimate of diffusion coefficients and determination of the photospheric convective regime. The photospheric convective overshooting is the basis of dynamic processes that determine the emergence and diffusion of solar magnetic field elements. We plan to study specific regions of the solar photosphere in order to evaluate the diffusion coefficients and the associated convective regimes. This information will allow us to better define the dynamics of plasma flows responsible for advection of magnetic elements and the energy budget associated with the photospheric turbulent motion responsible for the triggering of high frequency Magnetohydrodynamic waves.
3. Determination of the role of fluctuations in the heating of interplanetary turbulent plasma. The collisionless plasma in the interplanetary space is anomalously heated with respect to the simple adiabatic expansion. We will study the dynamics of the magnetic and electric fluctuations on small scales through analysis of satellite data and numerical simulations to determine the physical mechanisms that replace the usual dissipative processes in the solar wind plasma, and regulate the heating. Turbulent fluctuations at larger scales are also responsible for the modulation of the flux of energetic particles from the Sun through diffusion processes. A special data analysis will be devoted to better define the flux of these particles at the Earth’s orbit.
4. Determination of magnetospheric currents, concentration and composition of the plasmasphere, ULF waves during active magnetospheric conditions. The determination of the magnetospheric and ionospheric current systems associated with major perturbations allows to quantify basic aspects of magnetospheric dynamics and to test the performance of model representations of the magnetospheric field under unsteady conditions. Magnetospheric and ionospheric currents will be determined comparing magnetic field observations at geostationary orbit and those of the global network of digital geomagnetic observatories (INTERMAGNET) with model representations of the magnetospheric field. During geomagnetic storms, the plasmasphere is highly dynamic in its size, shape and plasma content/composition and its changes can have important influences on the acceleration, loss and transport processes of energetic particles in the radiation belts and then on the space technological systems. Our objective is to get a large scale picture of the time evolution of the concentration and composition of the plasma populating the Earth’s plasmasphere and of the ionosphere-plasmasphere coupling during geomagnetic storms through a coordinated analysis of measurements from ground-based ULF/VLF networks, ionospheric sounding stations and satellites. The combined use of multi-point measurements of unprecedented size should improve our current knowledge of the large scale dynamic processes which develop in the magnetosphere during perturbed conditions. A further important objective will be the understanding of a possible influence on the Earth’s atmosphere of the geomagnetic activity, due to the interaction between magnetosphere and solar wind structures, as well as to identify the degree of correlation between short and long term variations of the ULF waves activity in the Antarctic region and atmospheric parameters.
5. Estimate of input parameters in models of Space Weather and climate of space and Earth. The total and spectral solar irradiance are key parameters for the models climate on Earth and space. While accurate modeling of the measured variability helps improving the current knowledge on the mechanisms responsible for solar irradiance variations, precise prediction of future solar irradiance is important for the assessment of future climate changes. In this framework, we will explore the feasibility to use stochastic processes in predicting the solar irradiance variations. The performances of the system will be tested for different periods of the time-scale predictability, from short to medium terms. Results will be used in climate models and numerical simulations.
6. Development of a common pipeline of spectro-polarimetric analysis.
Through collaborations with the team we want to standardize the different spectro-polarimetric inversion softwares, locally developed up to now, and used in order to optimize the timing calibration of the magnetograms obtained from both ground-based and space-based instruments. The various codes will be standardized and documented by a specific Working Group to collect material for a Remote Web-based infrastructure.