Continuous, high quality observations of relativistic electron intensity by the van allen probes (VAP) scanning the full range of the radiation belts near the equatorial plane reveal that the entire…

This federal contract award, valued at $447,319.66, was granted to the University of California, Los Angeles (UCLA) by the National Aeronautics and Space Administration (NASA) to conduct research into relativistic electron enhancements in the Earth's outer radiation belt. The award, with a completion date of February 7, 2024, aims to investigate the primary parameters that influence the position, extent, and intensity of these electron enhancements, and how they vary with electron energy. The research will leverage data from the Van Allen Probes mission to understand the relationship between solar wind conditions, geomagnetic activity, and radiation belt dynamics - a key objective of the Van Allen Probes mission. This study directly supports NASA's goals to determine the dynamics and coupling of the Earth's magnetosphere, ionosphere, and atmosphere in response to solar and terrestrial inputs. The contract does not have a set-aside designation.

Continuous, high quality observations of relativistic electron intensity by the van allen probes (VAP) scanning the full range of the radiation belts near the equatorial plane reveal that the entire outer-belt often does not respond coherently to external forcing, and that solar wind and geomagnetic conditions can drive the outer-radiation belts into very different states, for which radial regions of enhancements and intensities of enhancements can be significantly different. Motivated by this important feature of the radiation belt that has not been comprehensively investigated before, the central objective of this proposal is to acquire a complete view of how relativistic electron enhancements in the entire outer radiation belt modulate with solar and magnetosphere conditions through determination of the primary parameters that control when, where, and how much relativistic electron enhancements occur in the radiation belts. They will primarily address the following questions: Q1. What are the primary parameters that determine radial position of maximum electron enhancement and radial extent of enhancement? Q2. What are the primary parameters that determine level of electron enhancement? Q3. How do the identified enhancement properties vary with electron energy? Q4. What are the average solar wind conditions for certain level of enhancement as function of electron energy and l? For outer-belt relativistic electron intensity over the full range of l, they will primarily analyze spin-averaged, differential electron data collected by the rept and mageis instruments onboard the VAP, along with electron flux at GEO by goes spacecraft. They will visually assemble well-defined electron enhancement events of any level for energies of ~0.5MEV to ~6.3MEV. First for one selected energy, they will derive functional relationship between radial position of maximum enhancement with dstmin. They will also determine how radial extent of enhancement as well as maximum enhancement are statistically related to AE, quantities derived from AE, such as SUM of AE and total time of AE being larger than a certain level during flux increase, and various solar wind parameters including IMF ULF power. They will examine correlations for timings and intensities between AE and seed electron flux (10S-100S KEV) and determine statistical relationship between electron flux and AE (or AE summed over the time of flux increase). They will then conduct the same analysis for all other energies and determine how all the statistical relationships, for different energies, between enhancement properties and AE (and the parameters derived from AE), IMF ULF power, seed electron intensity vary with energy. By superposed epoch analysis, they will determine average solar wind conditions necessary for a certain level of enhancement as a function of energy and l. The knowledge acquired in this project will give critical information on physical processes for enhancement and greatly contribute to prediction capability of large enhancement events. The proposed work will investigate how relativistic electron enhancements over the entire outer-belt modulate with solar wind and magnetosphere conditions, including magnetic storms and substorms. This investigation thus directly addresses one of VAP s mission goals, understand how the radiation belts change in the context of geomagnetic storms. Radiation belt electron dynamics are primarily driven by the solar wind. Determination of the relationship of solar wind conditions and geomagnetic activity, which is in turn driven by the solar wind, with relativistic electron enhancements will advance our understanding of how radiation belt electrons respond to solar wind variations. Therefore, this proposed study is directly relevant to decadal survey goals: determine the dynamics and coupling of earth s magnetosphere, ionosphere, and atmosphere and their response to solar and terrestrial inputs .