Progress Toward Implementation of the 2013 Decadal Survey for Solar and Space Physics A Midterm Assessment (2020) / Chapter Skim
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2 Science Discoveries and Technical Advances
2 Science Discoveries and Technical Advances
Pages 34-48
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From page 34... ...
, NASA's first scientific payload hosted on a commercial spacecraft. The twin Van Allen Probes were launched in August 2012, just before the decadal survey was published, and recently completed their mission to unlock the secrets of particle acceleration in Earth's Van Allen radiation belts.
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From page 35... ...
In the local interstellar medium, these shocks produce disturbances that were observed by Voyager 1 many astronomical units beyond the heliopause. Finally, the neutral solar wind is unimpeded by the heliopause and propagates into interstellar space where it interacts with the interstellar medium and is likely the primary source of the "ribbon" seen by NASA's Interstellar Boundary Explorer (IBEX)
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From page 36... ...
The multitude of perspectives and measurements are increasingly combined in system-wide numerical models, while machine learning is used with rapidly increasing frequency and skill to sift through the growing volumes of data. Learning about solar and space physics is also helped by the Sun itself: the unusually weak recent solar cycle gives us a better view of background processes that were until now generally masked by strong solar variability.
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From page 37... ...
the ion-neutral couplings that occur in settings as different as the solar chromosphere, Earth's ionosphere, and the interaction of the solar wind with the partially ionized interstellar medium. The importance of space weather continues to grow as illustrated by the recent development of the National Space Weather Strategy and Action Plan.
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From page 38... ...
. Among its primary findings are the need to investigate magnetic configurations and their potential instabilities in both the solar atmosphere and geospace; only advances in that area can lead to reliable, actionable space weather forecasts out to beyond the half day to one day required by, among others, the electric power providers, GNSS users in -- for example, drilling and mining, airlines operating high-latitude flights, delicate spacecraft operations on orbit or during launch, and crewed spaceflight activities in low-Earth orbit, on the Moon, or beyond.
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From page 39... ...
Citizen science is of growing importance in many areas of science, including solar and space physics. For this historic event, in situ data directly measured by low Earth orbiting satellites during the eclipse period was also available and is being studied.
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From page 40... ...
• Close to the Sun, the Parker Solar Probe has set the record for closest approach to the Sun; its ongoing mission is to sample solar coronal particles and the solar electromagnetic field to understand coronal heating, solar wind acceleration, and the formation and transport of solar energetic particles. • Far from the Sun, measurements by the Voyager spacecraft (that exited the heliosphere in 2012 and 2018, respectively) , combined with Interstellar Boundary Explorer (IBEX)
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From page 41... ...
However, the rise of bundles of magnetic field to the solar surface was found to be much slower than expected from some models (Birch et al., 2016) , meaning more theoretical work is needed to better understand how flux tubes rise through the surrounding gas. 2.3 SOLAR WIND-MAGNETOSPHERE INTERACTIONS Solar extreme ultraviolet radiation and the solar wind, including transients related to stream structure and coronal mass ejections, impinge on Earth's protective magnetic shield, producing a variety of conditions in Earth's space environment.
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From page 42... ...
• Space-weather conditions at Mars were studied with particular emphasis on the solar wind coupled to that planet's atmosphere with its weak, local magnetism. Selected discoveries discussed in detail in Appendix E for the four SWMI science challenges include understanding magnetic reconnection in the magnetosphere; energetic particle processes; coupling between the magnetosphere, ionosphere, and thermosphere; and different magnetospheric systems (e.g., other planets)
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From page 43... ...
to reveal the dynamics effects from solar variability, the cooling influence of anthropogenic methane and carbon dioxide, and even the top-down coupling of atmospheric changes resulting from the long-term change of the terrestrial magnetic field, of which the shift of the magnetic poles is one consequence. Selected discoveries are discussed in detail in Appendix E for the four AIMI science challenges, including understanding how the ionosphere-thermosphere system responds to magnetosphere forcing, plasmaneutral coupling processes, lower-atmosphere forcing effects in the ionosphere-thermosphere, and the causes for long-term changes in the AIM system.
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From page 44... ...
Some highlights include the following: • Ultra-high-resolution magneto-hydrodynamic (MHD) simulations of Earth's magnetosphere have been pushed to the limits of the physics that MHD can capture, revealing highly structured features in dipolarization fronts. • A new generation of whole-Earth atmosphere models now span from Earth's surface to the upper thermosphere and ionosphere and can capture the atmospheric driving of space weather effects.
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From page 45... ...
now span the altitude range from Earth's surface to the upper thermosphere with an interactive ionosphere and electric wind dynamo to connect tropospheric weather with space weather at resolutions capable of resolving mesoscale processes. While the simulations are more detailed than what can be currently observed, that does not mean the simulations are correctly emulating the observed physical processes.
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From page 46... ...
and solar wind (e.g., Camporeale et al., 2017) . One especially useful class of techniques, called machine learning and data mining, unearth patterns and behaviors in data sets that are difficult to discover via simple statistical relationships or by eye in a way that is scalable and reproducible (Ivezic et al., 2014; LeCun et al., 2015)
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From page 47... ...
2015. Solar flare prediction using SDO/HMI vector magnetic field data with a machine-learning algorithm.
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From page 48... ...
Journal of Geophysical Research: Space Physics 122:6882.
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