- Highest mean Nov-Mar 1000-500 mb thickness (5233 m vs 5218 m in 1980-1981). Thickness is an excellent measure of integrated heat content, which means that the lower half of the atmosphere above Fairbanks indisputably saw its warmest winter on record (since 1948).
- Highest mean Nov-Mar temperature at 850 mb, 700 mb, and 500 mb. At the surface it was the 6th warmest winter on record.
- Highest mean Nov-Mar 500 mb height (pressure aloft). Last winter (2013-2014) now stands in second place. Interestingly 2011-2012 saw the lowest mean 500 mb height on record.
It's interesting to note that more than 31% of soundings reported above-freezing temperatures somewhere in the column from November through March. This is more than twice the 1981-2010 normal of 14.8%, and is very close to the 1980-1981 record. It's remarkable to consider that above-freezing air can persist in the atmosphere above Fairbanks for almost one-third of the winter.
It's interesting to note that more than 31% of soundings reported above-freezing temperatures somewhere in the column from November through March. This is more than twice the 1981-2010 normal of 14.8%, and is very close to the 1980-1981 record. It's remarkable to consider that above-freezing air can persist in the atmosphere above Fairbanks for almost one-third of the winter.
Here's a time-height cross-section of the lower tropospheric temperature anomalies.
We've had a mild winter in Fairbanks. Is it as simple as having warmth aloft, or as noted, "thickness"? Are clouds a function of warmth aloft? It would seem they also play a role in determining temperatures at the surface. I'm trying to understand the important drivers of temperatures at the surface.
ReplyDeleteGary
Gary, I'll post some figures on cloud cover tomorrow. I think you'll find the results interesting.
DeleteThat first graph is remarkable. A statistician would be baffled, I think. As for forcings, according to the good folks at University of Washington, the December, January, and February PDO readings have ALL been the highest ever recorded in 115 years: http://research.jisao.washington.edu/pdo/PDO.latest
ReplyDeleteAndy, yes indeed - extremely positive PDO, although I've calculated the PDO with different SST data and different climatology, and it makes a difference... this winter may or may not have been a record depending on these choices.
DeleteI'd be curious for more comment on the thickness chart - exactly what is it that you see as statistically unusual? The sudden break of apparent decadal-scale trends in 1976 and 2013-2014?