The Solar Wind Transit Time product provides real-time graphical displays of solar wind parameters as observed at L1, with the bottom plot indicating the estimated transit time for the observed solar wind parcel to travel from L1 to Earth. The predicted time to Earth is determined by computing interplanetary magnetic field (IMF) tilt angles using a variation of the minimum variance technique, where the average magnetic field along the phase front normal (PFN) vector is equal to zero.
This product aims to improve arrival time predictions, including improvements to the predicted onset timing of geomagnetic storm warnings and improvements to the inputs driving geospace models.
This product is based on the minimum variance method described by Weimer and King  to define the tilt angles of interplanetary magnetic field (IMF) phase fronts in order to obtain more accurate arrival times for space weather events. This method is a combination of the cross-product technique and minimum variance analysis (MVA), with the constraint that the average magnetic field along the minimum variance direction is zero. Both methods must be in near agreement for the computed IMF tilt angles to be used in the determination of the expected transit time from L1 to Earth. If a valid tilt angle is not obtained, then a standard flat plane propagation method is used to compute the transit time.
This product uses 1-second averaged magnetometer data and 1-minute averaged plasma data and is updated every 5 minutes.
New and experimental product.