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Space Weather Forecasting

predicting the space environment for research and application

Space weather is the consequence of the ever-changing output of the sun in energetic particles and electromagnetic radiation which impacts the near-Earth space environment and can affect human activities.  Because of these effects we would like to be able to make predictions of when strong impacts might happen, so that system operators can make preparations to minimize damage.

The process of making these space-weather forecasts is much like the process of forecasting terrestrial weather:  We first attempt to determine the current state of the space environment as accurately as possible using observations and measurements.  Then the equations that describe how the plasma environment of the near-Earth space evolves and how it responds to stimuli are used to advance this state to make a prognosis of the state in the future.

One example of this kind of forecast deals with the occurrence of plasma irregularities in the ionosphere that can interfere with radio propagation and affect communication and navigation (GPS) systems. This interference occurs when naturally occurring waves in the ionosphere become large in amplitude and the ionosphere becomes turbulent, generally as the result of the nonlinear evolution of plasma instabilities. 

Figure 1: Low density structures of fast moving plasma.

To forecast the development of this turbulence, the conditions within the Earth’s magnetosphere/ionosphere/thermosphere system are examined for susceptibility to the occurrence of these instabilities, which are then tracked by predicting the development of structure in the plasma density when they occur.  When low-density structures of fast-moving plasma like the plume in  Figure 1 occur, they generally are full of the irregularities that lead to radio scintillation. 

Figure 2: Radio scintillation prediction overlay

From this structure, predictions of the strength of radio scintillation can be made, as shown overlaid on the map of the Americas in Figure 2.

The final stage of the forecasting process is validating the predictions by comparing them with subsequent observations made in the forecast time interval (see Figure 3: the red curves are the observations of scintillation strength as a function of time, the blue curves are the model predictions; each panel represents a different station in South America):

Figure 3: Model Predictions for South America.

Such a model has been developed by ISR personnel to be used to help understand the phenomena of ionospheric irregularities (to deal with some of the fundamental problems of space plasma physics) and improve our techniques for forecasting space weather (to provide a practical application).  It is currently running and being used at sites making space-weather predictions for commercial aviation, for Air Force satellites, and can be publically viewed at the NASA webpage:

Publications:

Retterer, J. M. (2005), "Physics-based forecasts of equatorial radio scintillation for C/NOFS", Space Weather, 3, S12C03.

Retterer, J. M. et al. (2005), "Assimilative modeling of the equatorial ionosphere for scintillation forecasting: Modeling with vertical drifts", J. Geophys. Res., 110, A11307.

Kelley, M. C. and J. M. Retterer (2008) “First successful prediction of a convective equatorial ionospheric storm using solar wind parameters”, Space Weather, 6, S08003, DOI.

Retterer, J. M. and L. C. Gentile (2009)  “Modeling the climatology of equatorial plasma bubbles observed by DMSP”, Radio Sci., 44, RS0A31, DOI.

Retterer, J. M. (2010) “Forecasting Low-Latitude Radio Scintillation with 3-D Ionospheric Plume Models: I. Plume Model”, J. Geophys. Res., DOI.

Retterer, J. M.(2010)  “Forecasting Low-Latitude Radio Scintillation with 3-D Ionospheric Plume Models: II. Scintillation Calculation”, J. Geophys. Res., DOI.

Retterer, J. M. et al. (2010)  “Modeling the low-latitude ionospheric electron density and plasma turbulence in the November 2004 storm period”, J. Atmos. Solar-Terr. Phys., DOI.

Su, Y.-J., J. M. Retterer, et al. (2009) "Assimilative modeling of equatorial plasma depletions observed by C/NOFS", Geophys. Res. Lett., 36, L00C02, DOI.

Kelley M. C., J. J. Makela, O. de La Beaujardière, and J. Retterer (2011) "Convective Ionospheric Storms: a Review”, Rev. Geophys., DOI.

Point of Contact for this project is John Retterer.