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Forecasts of solar and geomagnetic activityForecasts of solar and geomagnetic activity are critical since these quantities are such important inputs to the thermospheric density models. At this time in the history of solar science there is no way to make such a forecast from first principles. Physical theory applied to the Sun is developing rapidly, but is still primitive. Techniques used for forecasting depend upon the observations over about 130 years, which is only twelve solar cycles. It has been noted that even-numbered cycles systematically tend to be smaller than the odd-numbered ones by about 20 percent. Another observation is that for the last 12 cycle pairs, an even-numbered sunspot cycle looks rather like the next odd-numbered cycle, but with the top cut off. These observations are examples of approximate periodicities that forecasters try to use to achieve some insight into the nature of an upcoming cycle. Another new and useful forecasting aid is a correlation that has been noted between geomagnetic indices and the size of the next solar cycle. Some best estimates are given concerning both activities.
Document ID
19870011244
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Joselyn, Joann (National Oceanic and Atmospheric Administration Boulder, CO, United States)
Date Acquired
September 5, 2013
Publication Date
February 1, 1987
Publication Information
Publication: NASA. Marshall Space Flight Center Upper and Middle Atmospheric Density Modeling Requirements for Spacecraft Design and Operations
Subject Category
Solar Physics
Accession Number
87N20677
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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