For several months I've been meaning to create a climatology of upper-air temperatures for Alaska observing stations at various heights above the ground. The goal here is to visualize the evolution of temperature anomalies in a time-height cross-section, similar to the plot I showed
here, but for departure from normal as well as just temperature. Well, I finally got around to it, and the results are posted below for Fairbanks and Barrow since June 1.
There was a good deal of cool air around in June at both locations, with temperatures struggling to get much above freezing over Barrow until mid-June; but it's been quite warm lately, with freezing levels recently poking above 10,000 feet at Barrow. Chilly Arctic air has just returned to the North Slope, however: Barrow reported freezing drizzle and 0.05" of ice accumulation overnight last night.
Why does Barrow have so much cold air between 100' and 600' - especially for how warm the air is above? If it is arctic air trying to slip in why is the surface so much warmer?
ReplyDeleteEric, thanks for the question. I've added a panel on the right side of each plot showing the time-mean, so I think this clarifies the point you are making: the low-level air has been unusually cold while it's been a tad above normal above about 700m. But I would not say the surface has been much warmer: the mean surface temperature at PABR over the same period was 2.0F or 1.1C below normal.
DeleteI don't have an answer right now for where the low-level chill is coming from, other than the obvious idea that an Arctic air mass has prevailed. I do know that 2m temperatures were below normal over most of the Arctic Ocean in June, but I haven't looked at temperatures aloft.
On the North Slope cold air flowing over sea and ice is the source of cool surface temperatures and higher humidity during open water periods. If the wind is from inland it's relatively warmer and dryer up there in my experience.
DeleteHint: Don't stand in one place too long despite a breeze. Mosquitoes hover in turbulent air downwind and will endeavor to eventually approach and land. It's best to find a person close in that flow direction and let them feed on them .
Gary
Great time series graphics Richard. Makes for a very helpful visualization.
ReplyDelete