Heliospheric Weather Expert Service Centre - Product Browser

H101a - Solar wind model for Earth [WSA-Enlil (-2d < T < +5d)

The H101a Solar Wind Forecast is based on the well known WSA-Enlil model combination.

The data provided on the web page includes i) the Enlil model movie, ii) the cone files input into model and iii) a forecaster commentary on the expected outcome.

In the movie image, as shown on the web page, the Sun is represented as a yellow dot, the Earth by a green dot, and the STEREO spacecraft by the red and blue dots.  The top row represents the WSA-Enlil predicted solar wind density and the bottom row the predicted solar wind velocity.  On the left is a pinwheel plot of the ecliptic plane, showing all of the solar wind structures that are likely to encounter Earth or which have recently encountered Earth, in what is effectively an 'overhead' view.   In the middle are meridional slices that go through the Earth, showing the solar wind structures that will encounter Earth from a 'side' view.  On the right, the predicted density and velocity values for the location of Earth and the two STEREO spacecraft are plotted.

The CME characteristics that are used as input to the Enlil MHD simulation are generated by experienced MO forecasters analysing SOHO/LASCO images using a number of tools such as the SWPC CME Analysi Tools (CAT) and other supporting information.

The forecaster guidance is provided by the MO space weather forecast desk which is staffed 24x7 by professional forecasters who base their assessment based on all information available at the time. This signficicantly reduces the chance of false alerts that are raised by automated systems that do not have a forecaster in the loop.

Caveats:

• Please note that because the different parts of the product are loaded asynchronously into the archive it is possible that not all elements (plot, CME, forecaster guidance) will be available for the latest days until several days later. Please always use the Expert Group page (link provided) for access to the latest information.
  
  
• The uncertainty in the arrival time of a particular solar wind transient is dependent on a large number of factors including the underlying critical data used to drive the WSA part of the model (GONG magnetogram) and to determine the CME characteristics (SOHO/LASCO coronagraphs) which together form the starting boundary conditions for the Enlil MHD model. The typical uncertainty in arrival time is of the order of 12 hours. Please review the forecaster guidance since this provides an expert assessment based on all the available inputs at the time. For post-event analysis see the monthly product assessment reports

• While the STEREO spacecraft are shown, this ecliptic slice does not normally pass through these satellites, though it is typically fairly close. STEREO-B is not currently returning instrument data but STEREO-A is working well and is an important dip-stick for assessing forecasts on the far side of the Sun where accuracy is expected to be lower due to reliability of the critical data.