Sunday, March 22, 2015

Sunspot Numbers Plummeting, Stratosphere Warming

The number of sunspots has been anomalously low as of late, the lowest trend since roughly July 2014.

The above image shows sunspot numbers from NOAA over the past many months. Higher sunspot numbers (red) indicate that the sun is more active than usual. In the last couple of months, the number of sunspots has been dropping steadily from average values earlier in the year into 2014, interestingly enough in the midst of the strongest solar storm unleashed on the Earth in this solar cycle, per some reports.

What does this mean for our weather? The influence of the sun on our weather is still somewhat murky, but one big derivation we can make is that the stratosphere tends to cool down when the sun is active, and warm when the sun is quieter.

We are already seeing the stratosphere warm up, with more warming expecting in the future. The panels above show observed temperature values at different parts of the stratosphere in color, with the forecasted values in dashed lines. Notice how the ECMWF model expects the 10hPa level (top panel) to heat up notably, with a similar story in the 30hPa level (2nd panel from top). Although this warming won't be sustained, it's quite possible we see additional warming as the stratosphere exits its winter phase and enters its summer phase.

To summarize:

- Sunspot numbers have been steadily decreasing in the last few months, as we begin to end the current solar cycle.
- Stratospheric temperatures are responding by warming up, signaling and end to the winter phase.



Anonymous said...

Don't reduced sun spots eventually lead to global cooling if sustained for a prolonged period of time?

Anonymous said...

I'm curious about apparent minor equitorial warm at 10hPa, been going on for over two months. Is that normal?

Mike B said...

Looking at historical data there seems to be a correlation between increased sunspots/solar activity and decreased precipitation in Calif. Could the increased sunspot activity lead to the strengthening of the subtropical high pressure zones around the world? For example, causing or contributing to the drought in California?