skip to main content


Search for: All records

Creators/Authors contains: "Crew, A."

Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher. Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?

Some links on this page may take you to non-federal websites. Their policies may differ from this site.

  1. Abstract

    We used the Solar Anomalous and Magnetospheric Particle Explorer to identify and quantify the duration of relativistic,MeV, electron microbursts. A typical relativistic microburst has amillisecond (ms) duration, and the interquartile range of the duration distribution is 70–140 ms. We investigated trends in the microburst duration as a function of geomagnetic activity, L‐shell, and magnetic local time (MLT). The clearest trend is in MLT: the median microburst duration doubles from 75 milliseconds at midnight to 140 milliseconds noon MLT. This trend is similar to the whistler mode chorus rising tone element duration trend, suggesting a possible relationship.

     
    more » « less
  2. Abstract

    This study considers the impact of electron precipitation from Earth's radiation belts on atmospheric composition using observations from the NASA Van Allen Probes and NSF Focused Investigations of Relativistic Electron Burst Intensity, Range, and Dynamics (FIREBIRD II) CubeSats. Ratios of electron flux between the Van Allen Probes (in near‐equatorial orbit in the radiation belts) and FIREBIRD II (in polar low Earth orbit) during spacecraft conjunctions (2015–2017) allow an estimate of precipitation into the atmosphere. Total Radiation Belt Electron Content, calculated from Van Allen Probes RBSP‐ECT MagEIS data, identifies a sustained 10‐day electron loss event in March 2013 that serves as an initial case study. Atmospheric ionization profiles, calculated by integrating monoenergetic ionization rates across the precipitating electron flux spectrum, provide input to the NCAR Whole Atmosphere Community Climate Model in order to quantify enhancements of atmospheric HOxand NOxand subsequent destruction of O3in the middle atmosphere. Results suggest that current APEEP parameterizations of radiation belt electrons used in Coupled Model Intercomparison Project may underestimate the duration of events as well as higher energy electron contributions to atmospheric ionization and modeled NOxconcentrations in the mesosphere and upper stratosphere.

     
    more » « less