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NOAO Newsletter - National Solar Observatory - December 1997 - Number 52


New Synoptic Solar Maps from NSO

Just as global maps of weather on the Earth allow forecasters and researchers to understand and predict terrestrial weather, similar synoptic maps of solar activity have been constructed and used since 1915. In recent years, digital maps of the whole-Sun distribution of magnetic flux have been used as boundary conditions for numerical models of space weather. Such maps have been constructed from observations made with the Vacuum Telescope on Kitt Peak since 1975 and have been a popular data product used in many investigations.

The old maps suffer from several minor problems. In a project partly funded by the Office of Naval Research, the software used to make the maps is being rewritten to correct these problems and to add some new products. The first results are superior to those from the old processing, and the new products show several intriguing new aspects of solar activity.

As part of this project, a new web page is now on-line and presents the most current synoptic maps in three projections (latitude, sine latitude, and polar), and at several levels of reduction. The web page also allows access to an archive of past maps in the various formats and reduction levels. Perhaps the most concentrated map is one which shows the location of active regions, large-scale areas of magnetic flux polarity, and an estimate of coronal hole boundaries. The web page is accessible from the NSO/KP home page via the most recent solar images link.

As time permits, the archive of maps made will be replaced using the old processing with newly processed versions of the old data. A near-term goal is to produce maps of solar magnetic flux that account for differential rotation and evolution of solar activity on a near real-time basis for use in numerical modeling of transient solar activity such as coronal mass ejections. This involves gaining a better understanding of how magnetic flux evolves on the solar surface---a daunting research task.

Jack Harvey, John Worden


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