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The Precession Index, A Nonlinear Energy Balance Model, And Seversmith PsychrotermsAn important component of Milankovitch's astronomical theory of climate change is the precession index. The precession index, along with the Earth's tilt and orbital eccentricity, are believed to be the major controlling factors of climate change in the last few million years. The precession index is e sin omega(sub s) where e is the Earth's orbital eccentricity and omega(sub s) measures how close the Sun is to the Earth at midsummer. When omega(sub s) = 90deg the Sun is close to the Earth during northern summer, and at 270deg it is far from the Earth during northern summer. The precession index varies with time, because both the eccentricity e and the parameter omega(sub s) are constantly changing due to disturbances in the Earth's orbit by other planets, and due to the precession of the Earth, The change is largely periodic, with a period of about 23,000 years.
Document ID
Document Type
Preprint (Draft being sent to journal)
Rubincam, David Parry
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
September 7, 2013
Publication Date
January 1, 2004
Subject Category
Distribution Limits
Work of the US Gov. Public Use Permitted.
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