scholarly journals Possible Advantages of a Twin Spacecraft Heliospheric Mission at the Sun-Earth Lagrangian Points L4 and L5

2021 ◽  
Vol 8 ◽  
Author(s):  
A. Bemporad
Keyword(s):  
Remote Sensing ◽  
Magnetic Fields ◽  
Vantage Point ◽  
The Sun ◽  
Missing Information ◽  
Lagrangian Points ◽  
The Earth ◽  
Coronal Magnetic Fields ◽  
Solar Disturbances

After the launch of STEREO twin spacecraft, and most recently of Solar Orbiter and Parker Solar Probe spacecraft, the next mission that will explore Sun-Earth interactions and how the Sun modulates the Heliosphere will be the “Lagrange” mission, which will consist of two satellites placed in orbit around L1 and L5 Sun-Earth Lagrangian points. Despite the significant novelties that will be provided by such a double vantage point, there will be also missing information, that are briefly discussed here. For future heliospheric missions, an alternative advantageous approach that has not been considered so far would be to place two twin spacecraft not in L1 and L5, but in L4 and L5 Lagrangian points. If these two spacecraft will be equipped with in situ instruments, and also remote sensing instruments measuring not only photospheric but also coronal magnetic fields, significant advancing will be possible. In particular, data provided by such a twin mission will allow to follow the evolution of magnetic fields from inside the Sun (with stereoscopic helioseismology), to its surface (with classical photospheric magnetometers), and its atmosphere (with spectro-polarimeters); this will provide a tremendous improvement in our physical understanding of solar activity. Moreover, the L4-L5 twin satellites will take different interesting configurations, such as relative quadrature, and quasi-quadrature with the Earth, providing a baseline for monitoring the Sun-to-Earth propagation of solar disturbances.

Variations of the magnetic fields of the sun and the earth in 7?50 day periods

Solar Physics ◽  
1994 ◽  
Vol 152 (1) ◽  
pp. 291-296 ◽  
Author(s):  
V. P. Bobova ◽  
N. N. Stepanian
Keyword(s):  
Magnetic Fields ◽  
The Sun ◽  
The Earth

The Solaris Solar Polar Mission

2020 ◽  
Author(s):  
Donald M. Hassler ◽  
Jeff Newmark ◽  
Sarah Gibson ◽  
Louise Harra ◽  
Thierry Appourchaux ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Solar Physics ◽  
Polar View ◽  
Ecliptic Plane ◽  
Vantage Point ◽  
Mission Design ◽  
Future Research ◽  
The Sun ◽  
Gravity Assist ◽  
Solar Observations

<p>The solar poles are one of the last unexplored regions of the solar system. Although Ulysses flew over the poles in the 1990s, it did not have remote sensing instruments onboard to probe the Sun’s polar magnetic field or surface/sub-surface flows.</p><p>We will discuss Solaris, a proposed Solar Polar MIDEX mission to revolutionize our understanding of the Sun by addressing fundamental questions that can only be answered from a polar vantage point. Solaris uses a Jupiter gravity assist to escape the ecliptic plane and fly over both poles of the Sun to >75 deg. inclination, obtaining the first high-latitude, multi-month-long, continuous remote-sensing solar observations. Solaris will address key outstanding, breakthrough problems in solar physics and fill holes in our scientific understanding that will not be addressed by current missions.</p><p>With focused science and a simple, elegant mission design, Solaris will also provide enabling observations for space weather research (e.g. polar view of CMEs), and stimulate future research through new unanticipated discoveries.</p>

Periodic imbalances of kinetic and magnetic energies in rotating magnetohydrodynamic turbulent flows

2020 ◽  
Author(s):  
Rustem Sirazov ◽  
Arakel Petrosyan
Keyword(s):  
Magnetic Fields ◽  
Temporal Dynamics ◽  
Wave Packets ◽  
Homogeneous Turbulence ◽  
Initial Time ◽  
The Sun ◽  
Magnetohydrodynamic Turbulence ◽  
The Earth ◽  
Magnetohydrodynamic Flows ◽  
N Wave

<p>A significant number of observed flows in geophysics, astrophysics, and laboratory experiments are in a state of magnetohydrodynamic turbulence. Among them are flows in the Earth’s outer core, in plasma shells of Earth, planets, and satellites of the solar system with strong magnetic fields, as well as flows in the Sun, stars, and astrophysical disks. Despite significant advances in the study of turbulence under the conditions typical of thermonuclear fusion devices, studies of the fundamental properties of homogeneous turbulence in rotating magnetohydrodynamic flows are still fragmentary and mainly concern turbulence in astrophysical disks, the solar tachocline and convective region of the Sun, and two-dimensional magnetohydrodynamic flows on the β-plane. Only in a few exceptional works were the properties of magnetohydrodynamic turbulence studied by simple analytical methods using Fourier series for similarity parameters, characteristic of the Earth’s core.</p><p>The aim of this work is to study the influence of the interaction of Alfvén wave packets on the dynamics of homogeneous turbulence. The method of calculation o magnetohydrodynamic turbulence we developed allows numerical simulation at large characteristic times and large external magnetic fields. The proposed method of setting the initial conditions for the velocity field makes it possible to satisfy the divergence-free, homogeneity, and turbulence isotropy conditions, as well as to set an arbitrary spectral distribution of the energy at the initial time without additional calculations. Numerical experiments demonstrate a nontrivial behavior of turbulent kinetic and magnetic energies. It is shown that periodic imbalance in energies occurs in the system in the form of conversion of kinetic energy into magnetic energy and vice versa. The analysis of the results shows that the detected nontrivial temporal dynamics of turbulence is caused by the periodic collisions of Alfvén wave packets.</p><p>This work was supported by the Russian Foundation for Basic Research (project no. 19-02-00016).</p>

scholarly journals Comparison of the aerosol optical properties and size distribution retrieved by Sun photometer with in-situ measurements at mid-latitude

2016 ◽  
Author(s):  
Aurélien Chauvigné ◽  
Karine Sellegri ◽  
Maxime Hervo ◽  
Nadège Montoux ◽  
Patrick Freville ◽  
...  
Keyword(s):  
Remote Sensing ◽  
In Situ Measurements ◽  
The Sun ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Near Surface ◽  
Atmospheric Column ◽  
Fine Mode ◽  
Sun Photometer

Abstract. Aerosols influence the Earth radiative budget through scattering and absorption of solar radiation. Several methods are used to investigate aerosol properties and thus quantify their direct and indirect impacts on climate. At the Puy de Dôme station, continuous high altitude near surface in-situ measurements and low altitude ground-based remote sensing atmospheric column measurements give the opportunity to compare the aerosol extinction measured with both methods over a one year period. To our knowledge, it is the first time that such a comparison is realized with continuous measurements of a high altitude site during a long term period. This comparison addresses to which extend near surface in-situ measurements are representative of the whole atmospheric column, the aerosol Mixing Layer (ML), or the Free Troposphere (FT). In particular, the impact of multi aerosol layers events detected using LIDAR backscatter profiles is analysed. A good correlation between in-situ aerosol extinction coefficient and Aerosol Optical Depth (AOD) measured by the Aerosol Robotic Network (AERONET) Sun photometer is observed with a correlation coefficient around 0.80, indicating that the in-situ measurements station is representative of the overall atmospheric column. After filtering for multilayer cases and correcting for each layer optical contribution (ML and FT), the atmospheric structure seems to be the main factor influencing the comparison between the two measurement techniques. When the site lies in the ML, the in-situ extinction represents 45 % of the Sun photometer ML extinction while when the site lies within the FT, the in-situ extinction is more than two times higher than the FT Sun photometer extinction. Remote sensing retrievals of the aerosol particle size distributions (PSD) from the Sun photometer observations are then compared to the near surface in-situ measurements, at dry and at ambient relative humidities. When in-situ measurements are considered at dry state, the in-situ fine mode diameters are 44 % higher than the Sun photometer-retrieved diameters and in-situ volume concentrations are 20 % lower than of the Sun photometer-retrieved fine mode concentration. Using a parametrised hygroscopic growth factor applied to aerosol diameters, the difference between in-situ and retrieved diameters grows larger. Coarse mode in-situ diameter and concentrations show a good correlation with retrieved particle size distributions from remote sensing.

scholarly journals Is There an Oblique Magnetic Rotator Inside the Sun?

1983 ◽  
Vol 66 ◽  
pp. 235-235
Author(s):  
G.R. Isaak
Keyword(s):  
Magnetic Fields ◽  
Convection Zone ◽  
Detailed Account ◽  
The Sun ◽  
Magnetic Perturbation ◽  
The Earth ◽  
Solar Oblateness

AbstractThe size of the rotational splitting recently observed (Claverie et al., 1981) is correlated with the 12.2d variation in the measurements of solar oblateness observed by Dicke (1976) and implies a convection zone of depth of 0.1 Rʘ. The near equality of amplitudes of global velocity oscillations (Claverie et al, 1981) of the various m components of the l = 1 and l = 2 modes as seen from the Earth viewing the Sun nearly along the equator is unexpected for pure rotational splitting. It is suggested that a magnetic perturbation is present and an oblique asymmetric magnetic rotator with magnetic fields of a few million gauss is responsible. A more detailed account was submitted to Nature.

Role of Satellite Technology in Oceanic Study

2018 ◽  
pp. 80-103
Author(s):  
Thomas Mathew
Keyword(s):  
Remote Sensing ◽  
Electromagnetic Radiation ◽  
Crucial Role ◽  
Near Infrared ◽  
Thermal Infrared ◽  
Microwave Region ◽  
Satellite Technology ◽  
The Earth

The three-fourth surface of the earth is covered with ocean. The study of the ocean is important for sustainable overall development of a nation and world at large in view of it being rich in resources and playing a crucial role in the climate of the region and changes associated with it. The space-based observations assume significance, as it provides synoptic and repetitive coverage of the ocean in contrast to the sparse and isolated in-situ buoy or ship observations. The remote sensing of the ocean with the help of satellite or satellite oceanography has many other applications also. The electromagnetic radiation in the visible, near infrared, thermal infrared, and microwave regions are used by the sensors on-board space platforms to measure the diverse physical, biological, and geological parameters of the ocean. Amongst the various electromagnetic regions, the microwave region plays an important role in the study of the ocean.

scholarly journals Comparison of the aerosol optical properties and size distribution retrieved by sun photometer with in situ measurements at midlatitude

2016 ◽  
Vol 9 (9) ◽  
pp. 4569-4585 ◽  
Author(s):  
Aurélien Chauvigné ◽  
Karine Sellegri ◽  
Maxime Hervo ◽  
Nadège Montoux ◽  
Patrick Freville ◽  
...  
Keyword(s):  
Remote Sensing ◽  
High Altitude ◽  
In Situ Measurements ◽  
Aerosol Extinction ◽  
The Sun ◽  
Near Surface ◽  
Atmospheric Column ◽  
Fine Mode ◽  
Sun Photometer

Abstract. Aerosols influence the Earth radiative budget through scattering and absorption of solar radiation. Several methods are used to investigate aerosol properties and thus quantify their direct and indirect impacts on climate. At the Puy de Dôme station, continuous high-altitude near-surface in situ measurements and low-altitude ground-based remote sensing atmospheric column measurements give the opportunity to compare the aerosol extinction measured with both methods over a 1-year period. To our knowledge, it is the first time that such a comparison is realised with continuous measurements of a high-altitude site during a long-term period. This comparison addresses to which extent near-surface in situ measurements are representative of the whole atmospheric column, the aerosol mixing layer (ML) or the free troposphere (FT). In particular, the impact of multi-aerosol layers events detected using lidar backscatter profiles is analysed. A good correlation between in situ aerosol extinction coefficient and aerosol optical depth (AOD) measured by the Aerosol Robotic Network (AERONET) sun photometer is observed with a correlation coefficient around 0.80, indicating that the in situ measurements station is representative of the overall atmospheric column. After filtering for multilayer cases and correcting for each layer optical contribution (ML and FT), the atmospheric structure seems to be the main factor influencing the comparison between the two measurement techniques. When the site lies in the ML, the in situ extinction represents 45 % of the sun photometer ML extinction while when the site lies within the FT, the in situ extinction is more than 2 times higher than the FT sun photometer extinction. Moreover, the assumption of a decreasing linear vertical aerosol profile in the whole atmosphere has been tested, significantly improving the instrumental agreement. Remote sensing retrievals of the aerosol particle size distributions (PSDs) from the sun photometer observations are then compared to the near-surface in situ measurements, at dry and at ambient relative humidities. When in situ measurements are considered at dry state, the in situ fine mode diameters are 44 % higher than the sun-photometer-retrieved diameters and in situ volume concentrations are 20 % lower than those of the sun-photometer-retrieved fine mode concentration. Using a parameterised hygroscopic growth factor applied to aerosol diameters, the difference between in situ and retrieved diameters grows larger. Coarse mode in situ diameters and concentrations show a good correlation with retrieved PSDs from remote sensing.

The magnetic Sun

2008 ◽  
Vol 366 (1871) ◽  
pp. 1735-1748 ◽  
Author(s):  
Richard A Harrison
Keyword(s):  
Magnetic Fields ◽  
Stellar Atmospheres ◽  
Magnetic Star ◽  
The Sun ◽  
Basic Principles ◽  
Fundamental Nature ◽  
James Clerk Maxwell ◽  
The Earth ◽  
Basic Equations ◽  
The Way

The nature of our star, the Sun, is dominated by its complex and variable magnetic fields. It is the purpose of this paper to review the fundamental nature of our magnetic Sun by outlining the most basic principles behind the way the Sun works and how its fields are generated, and to examine not only the historical observations of our magnetic star, but, in particular, to study the wonderful observations of the Sun being made from space today. However, lying behind all of this are the most basic equations derived by James Clerk Maxwell, describing how the magnetic fields and plasmas of our Sun's atmosphere, and indeed of all stellar atmospheres, work and how they influence the Earth.

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