Science Seminars

3/3/2016 – Tom Woods; Jack Eddy’s Study of the Maunder Minimum Inspires a Long Series of Satellite-Based Solar Irradiance Measurements: LASP and HAO solar irradiance projects between 1970 and 2010

Speaker: Tom Woods (LASP)
Date: Tuesday, Mar 03, 2020
Time: 4:00 PM
Location: SPSC W120

Seminar Abstract:

What if Jack Eddy hadn’t rediscovered the work by Gustav Spörer and Edward W. Maunder about the period of few sunspots in the 17th century? Would there be much interest today in understanding the solar “constant”, or would there be robust observational programs in measuring the solar irradiance and its variability and studies about Sun-Climate? Jack’s thorough analysis of the sunspot record led him to identifying two periods of low solar activity that he named the Maunder Minimum between 1645 and 1745 and the Spörer Minimum between 1460 and 1550. He published those results in a landmark paper titled “The Maunder Minimum”, and he also raised the questions about the possible solar influence on Earth’s Little Ice during those times [Eddy, Science, 192, 1189, 1976]. His research inspired many studies of the Maunder Minimum and has been an inspiration to accurately observe the solar irradiance variability. While ground-based measurements of the solar “constant” go back to the 1830s, observations of true solar variability became possible only with space-based measurements that began in 1978. The discovery of the Antarctica ozone hole in the mid 1980s was another key factor during that era for motivating accurate and continuous observations of the solar ultraviolet irradiance. The total solar irradiance (TSI) and solar spectral irradiance (SSI) observations from satellites will be presented along with a few highlights about the solar variability during the past four decades. The most recent cycle, Solar Cycle 24, has much lower solar variability than the other space-era solar cycles, and there is a petition underway to name this new low solar activity period as the Eddy Minimum.