National Aeronautics and Space Administration

Living With A Star

Targeted Research and Technology

Preconditioning of the interplanetary medium as responsible for large intense SEP events: Radial and longitudinal effects

ROSES ID: NNH10ZDA001N      Selection Year: 2011      

Program Element: Focused Science Topic

Principal Investigator: David Lario

Affiliation(s): Applied Physics Laboratory

Project Member(s):
Decker, Robert B. Co-I Johns Hopkins Univ. Applied Physics Lab.
Agueda, Neus Collaborator University of Barcelona
Ho, George C Collaborator Johns Hopkins University Applied Physics Laboratory

Summary:

We propose to study the factors that control both the highly variable intensity of solar energetic particle (SEP) events and the evolution of the SEP events as observed in the inner heliosphere. In particular, we will investigate both observationally and numerically how the preconditioning of the interplanetary (IP) medium determines the particle intensities observed at different locations in the inner heliosphere, paying special attention to those events that lead to the highest particle intensities and fluences observed throughout a solar cycle and those events that have been and will be observed from multiple heliospheric locations at radial distances R<=1 AU.



Solar Cycle 23 has offered us several SEP events with particle intensities above the previously determined streaming limit. Arguments to explain intensities exceeding the streaming limit invoke IP conditions that inhibit the amplification of waves able to scatter energetic particles and/or the presence of IP structures able to confine and/or mirror energetic particles. Therefore, the preconditioning of the IP medium clearly determines the intensity of these events.



Studies of the longitudinal and radial dependence of SEP intensities are required to correctly interpret multi-spacecraft observations. Solar Cycle 24 will provide us with SEP events observed by spacecraft widely separated in longitude at ~1 AU from the Sun (i.e. STEREO and near-Earth spacecraft) and by spacecraft located closer to the Sun (i.e., MESSENGER). The conditions of the IP medium sampled by SEPs arriving at each spacecraft may be different and hence that the characteristic of the same SEP event may differ from one spacecraft to another. The preconditioning of the IP medium leads to radial gradients that diverge from power laws usually inferred either from average statistical samples of events based on Helios and near-Earth observations or from uniform transport simulations.



We propose to combine multi-spacecraft observations with modeling based on two well-tested particle transport codes to (1) examine how the preconditioned IP medium determines the characteristics of the SEP events observed at different heliospheric locations; (2) model the effect that solar wind disturbances have on the transport of SEPs, and (3) determine the radial and longitudinal gradients of both SEP intensities and periods of elevated particle intensities at inner heliospheric locations where spacecraft such as Solar Orbiter and Solar Probe Plus will travel.



The proposed work includes (1) an observational element that involves focused analyses of plasma, magnetic field, and energetic particle data from spacecraft such as ACE, STEREO, GOES, IMP-8, Helios and MESSENGER; and (2) a theoretical element that involves modifying and expanding existing energetic particle transport models to include field configurations and transport conditions representative of those wherein SEP events develop.



The proposed research has a direct impact on the prediction of the highest SEP intensities that can be observed near-Earth and/or at any heliocentric distance <1 AU, with clear implications for particle instruments and spacecraft components on board spacecraft traveling close to the Sun. The proposed study will allow us to (1) understand the role that the preconditioning of the IP medium plays in the observation of SEP events at different heliospheric locations, and (2) modify the current models of SEP events to incorporate specific boundary and transport conditions.

Publications:

Performance YearReferenceInvestigation TypeActions
1Agueda N.; Lario D.; Ontiveros V.; Kilpua E.; Sanahuja B.; V...
Data Model Comparison
2Agueda N.; Vainio R.; Dalla S.; Lario D.; Sanahuja B.; (2013...
Data Model Comparison
2Lario D.; Ho G. C.; Roelof E. C.; Anderson B. J.; Korth H.; ...
Data Analysis
2Lario D.; Aran A.; Gomez-Herrero R.; Dresing N.; Heber B.; H...
Data Analysis
2Lario D.; Ho G. C.; Roelof E. C.; Decker R. B.; Anderson B. ...
Data Analysis
3Lario D.; Karelitz A.; (2014). Influence of interplanetary c...
Data Analysis
3Lario D.; Roelof E. C.; Decker R. B.; (2014). Longitudinal D...
Other Investigations
4Lario D.; Raouafi N. E.; Kwon R.-Y.; Zhang J.; Gomez-Herrero...
Data Analysis
4Gomez-Herrero R.; Dresing N.; Klassen A.; Heber B.; Lario D....
Data Analysis
4Lario D.; Decker R. B.; Roelof E. C.; Vinas A.-F.; (2015). E...
Data Analysis
4Lario D.; Decker R. B.; Roelof E. C.; Vinas A.-F.; (2015). E...
Data Analysis
5Riley P.; Caplan R. M.; Giacalone J.; Lario D.; Liu Y.; (201...
Data Analysis
5Lario D.; Kwon R.-Y.; Vourlidas A.; Raouafi N. E.; Haggerty ...
Data Analysis
5Agueda N.; Lario D.; (2016). Release History and Transport P...
Data Model Comparison
5Gomez-Herrero R.; Dresing N.; Klassen A.; Heber B.; Temmer M...
Data Analysis

Presentations:

Performance YearReferenceActions
1Lario, D.; Ho, G. C.; Roelof, E. C.; (2011), Multi-po...
1Decker, R. B.; Lario, D.; (2011), SEP Events at Distan...
1Lario, D.; Roelof, E. C.; Ho, G. C.; (2012), Multi-spacecraf...
1Lario, D.; Aran, A.; Decker, R. B.; Ho, G. C.; (201...

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