Thursday, 08 Aug 2013, 1:45 PM: The sun is the main driver of all weather and climate on Earth and it remains rather quiet in recent days despite the fact that something big is about to happen as we approach the expected solar maximum for this particular solar cycle. Indeed, according to recent measurements from NASA observatories, the sun’s vast magnetic field is about to flip with the sun’s north pole going from negative to positive and the south pole reversing from positive to negative. It looks like we may be about 3 or 4 months away from a complete magnetic field reversal on the sun which happens regularly at the peak of each solar cycle approximately every 11 years or so. The complete reversal will mark the midpoint of solar cycle 24 with half of the solar max period behind us and half yet to come. The typical process involved on the sun during this transition period first involves a weakening of the sun’s polar magnetic fields, then they go to zero, and then they emerge again with the opposite polarity – all a regular part of the solar cycle. While these transitions can stir up stormy space weather around our planet and cosmic rays can be affected, there is typically not a serious impact here on Earth from these solar magnetic field reversals.
Solar cycle 24 is now well over four years old and it continues to “underwhelm” and be on a pace that would make it the smallest sunspot cycle since Cycle 14 which peaked in February 1906. There is a growing feeling that, based on the recent inactivity, the peak may have already happened during the latter part of 2011. Another theory suggests that there may be a “double-peak” solar maximum for this cycle which would mean there could be a sharp spike in sunspot activity still to come later this year or in 2014.
Solar cycle 24 began after an unusually deep solar minimum that lasted from 2007 to 2009 which included more spotless days on the sun compared to any minimum in almost a century. While a weaker solar cycle does not rule out the threat for strong solar storms, it does suggest that they will occur less often than during the stronger and more active cycles. The increasingly likely outcome for a weak solar cycle continues the recent downward trend in sunspot cycle strength that began over twenty years ago with solar cycle 22. In addition, there are some solar scientists who are already predicting that the next cycle, 25, will be even weaker than this current one. According to some research studies, weak solar cycles with extended lengths may actually have a downward effect on global temperatures in the medium and longer range. Weak solar cycles tend to last longer than the strong ones. There have been historical periods with minimal sunspot activity that lasted for several decades such as from the mid 1600’s to the early 1700’s when the so-called “Maunder Minimum” occurred and this period was quite cold globally.
In addition to the cycles on the sun, of critical importance to weather and climate on Earth are our oceanic cycles. An interesting aspect to this apparent weakening solar cycle trend is that it looks like it will coincide with a cold phase of the northern Pacific – the largest ocean on Earth. The sea surface temperature anomalies in the northern Pacific Ocean are tracked through an index called the Pacific Decadal Oscillation (PDO). The PDO slipped into a negative (cold) phase a few years ago and these oceanic cycles can last for two or three decades. Global temperature anomalies have indeed trended downward over the past few years seemingly right after the PDO flipped to a negative (cold) phase. We’ll continue to periodically report on the latest solar activity here at “thesiweather.com” as well as the all-important oceanic cycles to monitor any important changes that may unfold.
A detailed video discussion on this is available here