Monday, March 1, 2010

End of the solar minimum

February 2010 was the first month in three years in which the Sun has sunspots every day of the month. This is a sign of the end of an unusually long and deep "solar minimum" -- which is the term for the lower portion of a regular eleven-year cycle of sunspots. In 2009, there were 260(!) days without sunspots. Nevertheless, 2009 was tied for the second-warmest year in the instrument record.

The influence of solar variability on the climate is modest -- the sun's intensity varies by a maximum of about 1 W/m^2. But in the short term, especially given the likely persistence of an El Nino through Spring, the upswing in solar radiance may contribute to record-breaking warmth. January and February 2010 were the hottest and second-hottest months in the satellite record, respectively -- which likely makes them among the hottest in the last 1,200 years.

No comments:

Post a Comment