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SPIDR Online Data Access & Plots
US Total Electron Content

Introduction

Vertical Soundings (Ionograms) 

History

Definition of Structure

Dynasonde

Catalog of Characteristics

Ionospheric Related Models

Ionospheric Indices (defined)

Scintillation Predictions

HF Radio Interest


Click here for a demo of the
diurnal variation in the ionosphere


Forecasting Ionospheric Real-time Scintillation (FIRST) Tool


By monitoring the height rise of the equatorial ionospheric F layer near dusk, an evening equatorial scintillation forecast is possible. Previous studies established a relationship between the Pre-Reversal Enhancement (PRE) vertical ExB drift and the scintillation S4 index. The FIRST technique extends this understanding by establishing a relationship between the readily available ionosonde produced h'F characteristic and ExB drift. h'F is defined as the minimum height of the ionospheric F layer Ordinary mode trace. With this new relationship in hand, an evening forecast is made possible. NGDC's Mirrion ionosonde measurement processing system provides real time data to support FIRST. At present, FIRST includes a forecast for the regions near Jicamarca and Kwajalein. Other longitudes are presently under pursuit. The FIRST technique is most directly related to scintillation in the VHF band.

The technique employed represents an active area of research and might be utilized to enhance the usual suite of forecaster tools.

Future work will include:
  • Create full documention of FIRST for public consumption
  • Qualify the use of these forecasts. Many different mechanisms can contribute to ionospheric scintillation. It is difficult, especially during low solar activity to differentiate between these mechanisms.
  • Investigate whether there are known causal relationships between VHF scintillation and GPS scintillation to extend FIRST to the navigational user.
  • Submit the FIRST paper for publication to the Space Weather journal
  • Make past FIRST forecasts and THMS4 values publicly available
  • Acquire additional, real-time, equatorial h’F values at other longitudes, e.g. Brazilian, Indian and African sectors
  • Theoretically examine, the R-T growth rates and threshold h’F (1930 LT) values as a function of solar cycle activity by incorporating a suite of first-principle models of the ambient ionosphere (PBMOD) developed at the Air Force Research Lab (AFRL)

Past forecasts are available here.