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Heliospheric Weather Expert Service Centre - Product Browser |
The Sun continuously emits a solar wind outflow with an average speed of about 400-500 km/s. From coronal holes, which are regions of open magnetic field on the Sun, a higher than average solar wind flow is emanated, having speeds of the order of greater than 500 km/s up to roughly 800 km/s. The solar wind of increased speed, may have space weather effects, and may influence the performance and reliability of space-borne and ground-based technological systems.
Based on a relation between EUV observations of the area of coronal holes on the Sun and the solar wind speed as measured at 1AU, the empirical solar wind speed forecast model (ESWF) was developed (see Vrsnak, Temmer, and Veronig, 2007; Rotter et al., 2012; Reiss et al., 2016) and revised (Milosic et al., 2022) with improved acccuracy and a newly developed Dst index forecast. The service, based on this model, is automatized and provides on an hourly basis solar wind speed forecasts with a lead-time of about 4 days.
The Empirical Solar Wind Forecast version 3.2 (ESWFv3.2) uses coronal hole (CH) areas extracted from SDO/AIA EUV images (left) as a basis to predict the solar wind speed at Earth (right top panel) and the Dst index (right bottom panel), both with an average time lag of approximately four days (magenta shaded area). The forecasted solar wind speed profile is compared to ACE/DSCOVR real-time in-situ measurements and the Dst index with quicklook Kyoto Dst data (dashed profile) as well as with the final Dst data (solid line). ESWFv3.2 covers a dynamic thresholding for CH extraction, the co-latitude information for the center of mass of the extracted CH, a newly developed algorithm for better simulating the compression region between slow and fast solar wind (PILE algorithm), and the Dst index forecast based on the CH underlying magnetic field from SDO/HMI data. A more detailed product description and references can be found here on main product page here.
The currently supplied data file (accessed from the link next to the time above each plot) provides approximately the last months worth of data with each new SDO image (approximately every hour) adding and additional record to the end and pruning the first record from the start.
The file is in fixed format ASCII with an initial header record describing each of the columns
| Parameter | Description |
|---|---|
| SDO_YEAR | The four digit year corresponding to the date when the SDO image was taken |
| SDO_DOY | The decimal day of year when the SDO image was taken |
| SDO_DATE | The date of the SDO image represented in ISO8601 calendar date format |
| SDO_RATIO_7.5 | The ratio of coronal hole in the 7.5 degree meridional cut |
| V_YEAR | The four digit year corresponding to the date for which the forecast speed corresponds |
| V_DOY | The decimal day of year when forecast speed correspond |
| V_DATE | The date for the forecast speed represented in ISO8601 calendar date format |
| V (km/s) | The forecast speed |
| B_YEAR | The four digit year corresponding to the date for which the forecast magnetic field corresponds |
| B_DOY | The decimal day of year when forecast magnetic field correspond |
| B_DATE | The date for the forecast magnetic field represented in ISO8601 calendar date format |
| B (nT) | The forecast magnetic field The empirical relation for forecasting B is currently unreliable and these values should not be used] |