The IDV Index: Its Derivation and Use in Inferring Long-Term Variations of the Interplanetary Magnetic Field Strength

Abstract

On the basis of a consideration of Bartels' historical u index of geomagnetic activity, we devise an equivalent index that we refer to as the interdiurnal variability (IDV). The IDV index has the interesting and useful property of being highly correlated with the strength of the interplanetary magnetic field (B; R2 = 0.75) and essentially unaffected by the solar wind speed (V; R = 0.01) as measured by spacecraft. This enables us to obtain the variation of B from 1872 to the present, providing an independent check on previously reported results for the evolution of this parameter. We find that solar cycle average B increased by approximately 25% from the 1900s to the 1950s and has been lower since. If predictions for a small solar cycle 24 bear out, solar cycle average B will return to levels of 100 years ago during the coming cycle(s).

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Document Details

Document Type
Technical Report
Publication Date
Dec 13, 2005
Accession Number
ADA452567

Entities

People

  • Edward W. Cliver
  • Leif Svalgaard

Organizations

  • Air Force Research Laboratory

Tags

Communities of Interest

  • Energy and Power Technologies
  • Space

DTIC Thesaurus Topics

  • Air Force
  • Air Force Research Laboratories
  • Cross Correlation
  • Cycles
  • Data Sets
  • Latitude
  • Magnetic Fields
  • Military Research
  • Observatories
  • Personal Information Managers
  • Solar Activity
  • Solar Cycle
  • Solar Wind
  • Spacecraft
  • Square Roots
  • Sunspots
  • Vehicles

Readers

  • Allergy and Immunology.
  • Space/Atmospheric Physics.
  • Systems Analysis and Design

Technology Areas

  • AI & ML
  • AI & ML - Bayesian Inference
  • Space