D-Region Absorption Prediction Product Archive

D-RAP image

The D-Region Absorption Prediction (D-RAP), Release 2 Product , produced by the Space Weather Prediction Center (SWPC), provides a suite of graphic and text information about global High Frequency(HF) radio propagation conditions relating of the ionosphere's D-region. The D-Region of the ionosphere is critically important to the propagation of HF radio signals. The lowest available frequency for HF users is directly related to the electon density in the D-Region. Due to space weather effects, the electron density can vary dramatically over time scales as short as a few minutes. The D-RAP Model uses empirically determined relationships to compute HF absorption and the highest affected HF frequencies directly from space weather input parameters.

The D-RAP2 Product Description Document (PDD), the Space Weather Journal article - Ionospheric Radio Wave Absorption and the D-RAP Technical Documentation provide additional information pertaining to the operational D-RAP product, the Ionospheric D-Region and the impacts of X-ray and Proton flux on HF communication

The D-Region Absorption Prediction Product is provided by SWPC as part of its mandate to provide real-time monitoring and forecasting of solar and geophysical events. NCEI is the National Archive for the D-RAP model outputs.

Model Inputs:
The D-RAP model uses GOES X-ray flux, GOES proton flux , estimated planetary geomagnetic activity index (Kp) , and monthly L-values derived from the IGRF main field geomagnetic model as inputs.

Product Outputs:
  1. A global map of the highest HF frequencies affected by a 1 dB attenuation, estimated recovery time - PNG graphics file
  2. A north pole map of the highest frequencies affected by a 10dB attenuation, estimated recovery time - PNG graphics file
  3. A south pole map of the highest frequencies affected by a 10dB attenuation, estimated recovery time - PNG graphics file
  4. ASCII tabular values of total absorption at 10 MHz - text file

The D-Region Absorption Prediction Product - Release 2, became an official NWS product on November 18th, 2009. For more information on D-RAP or to comment on the D-RAP product, please visit the SWPC real-time D-RAP2 Web Site.

D-Region Major Event Animations

Major X-level X-ray Events since 2000 Smaller M-level X-ray Events

Bastille Day-Jul 14, 2000

Apr 06, 2001

Oct 28, 2003

Nov 04, 2003

Oct 05, 2002

Nov 18, 2002

Apr 02, 2001

Oct 31, 2002

Oct 29, 2003

Jul 16, 2004

Dec 20, 2002

Jan 07, 2003