Hotter in Hobart? It all depends…
OK, under the https://chiefio.wordpress.com/2010/04/05/ascension-decending/ thread we had a comment about the trend being toward colder in Tasmania, followed by dropping a whole bunch of stations. (see the comment by Keith Hill ) and that got me wondering…
So I whacked together a version of the dT/dt code that let me put in ‘latitude limits’ in addition to country codes, and sure enough, we had stations dropping from about 30 in 1971 to 3 in 2004 (and some of them were on other islands than Tasmania…)
What to do? There were loads of “splice” artifacts in the combined graphs. There were “issues” that looked like they would take a long time to sort out. So I focused in on “Hobart” (and found out there were 2 “Hobarts”… so more “splice” artifacts. OK, I chose to just look very closely at “Hobart Airport”. The record had an early start date and continued to the present. What could “go wrong”?
Hobart Airport Anomalies Graph
Wait a moment… Keith said things were dropping and this is a clearly rising trend at the “Survivor”.
But it looks “wrong”… It has a spectacular bullseye near the start, then in the late 1990s to 2000 the almost complete lack of “negative going monthly excursions”. Not a bit of “cold” from 1998 to 2001 (or so)? Just what is going one here?
Ah, a partial answer, that “bullseye” is where we jump from 1854 to 1958. There is a Century missing. Wonder where it went?
So I’ve made a graph putting a ‘break” at that point. 1958 the anomalies are ‘all zero” (the heart of the bullseye) and 1959 only starts in June, so I’ve put the break in the graph at the 1959 / 1960 transition where we get our first year of data.
Gee, we were dropping like a rock, and suddenly lost a Century of data. Wonder why?
Then we pick up again rising out of the cold 1960 – 1970 era, but even then with a fairly flat trend line. There were a couple of volcano events then, and we recovered. OK. But also of interest is that “Dip” in 1997 – 1999. Wasn’t that “The Hottest Year Ever”? Is this, perhaps, evidence of a “Polar Oscillator” with the North being very hot when the South is very cold? We saw some evidence for this in the southern ocean discussion under the Ascension Descending thread. But this is a just spectacular droop. Probably a very interesting “Dig Here!” for a general understanding of how our global weather works.
But even that Blue Segment looks “wrong”. It’s trucking along doing a -1 C to Zero oscillator thing… just happy as can be and steady right up to that “droop”, then it simply loses it’s bottom.
The tops stay at Zero Anomaly, but the bottoms just fade away. Is there NO volatility AT ALL in Tasmania today? Golly, must be the easiest job ever for a weather man…
But we’ve seen this before. In France. When they went to 92% airports… And this is an airport. Could the same tool that helped us there, help us here? Looking directly at the actual temperatures?
Hobart, The Real Deal
OK, no interpolations, fill-ins, anomalies, nothing. Just the monthly temperature data, plotted.
Now that is one very interesting graph.
Stare at it for a while. Notice anything?
Like the narrowing of the width in the present?
Like the rising winter temperatures, but the falling summer temperatures?
The “hot pink” line is the annual average and it has a slight tilt upwards, but only because the DROP in December and January (summer) is not as large as the rise in winter ( May, June, July, August).
We saw very early on that “Global Warming” was not active in summer, but here it is “negatively active” in summer… and “neutral” in the swing months like November and March.
Inland a ways from Hobart, but also an airport. Where Hobart is the largest city in Tasmania, Launceston is the second largest. What does it look like?
(You can click on the graph to get a much larger version)
Oddly, the winters are “dead flat” while the summers have a slight rise to them. But a look in the wiki article for Launceston says that it has loads of winter fog. Airports don’t run much in the fog. Nor do they solar heat then. From the article:
Winter, for Launceston, is also the season with the least amount of wind. Because of this and the topographical affect of the Tamar Valley, Launceston winters are renowned for foggy mornings, with Launceston Airport the most fog-bound commercial airport in Australia.
So when the airport doesn’t run much, nothing changes.
But wait, there’s more… At the top of the graph the Dec an Mar lines (blue and yellow) are almost on top of each other and also on top of the ‘guide line’ at 15 C. Toward the bottom, the Oct and Sept trend lines are both slightly dropping (orange and deep blue). The “swing months” are not warming and in some cases slightly cooling.
Now, lets go back to those “warming” summer months at the top (Jan / black, Feb / red). Notice that the “rise” looks to largely happen in the early years? From 1939 to 1960. The transition from grass strips to tarmac and pavement. The growth of the Jet Age. Since then, the “tops and bottoms” have run more or less about 19 C and 15 C. There might be a trivial rise to it (about like the Sept drop) but the bulk of the “rise” is long gone.
So we’re left with “nothing much happening” after the Commercial Expansion is over. And with a bit of solar heated runway and tarmac parking areas, and maybe some terminal growth UHI; but a place that does not get warmer when the planes are grounded and fog blocks the sun.
Many local site issues, not a scrap of “climate change”. IMHO, that’s the story across the globe. And “homogenizing” it all together will not turn local site issues into climate issues.
It looks to me like we have a falling trend in Hobart, but that at the airport the Airport Heat Island can overcome it, especially during winter. I would speculate that summers are not as sunny in Hobart as they are in the south of France, as we ware lacking the “lift’ of the summer months that we saw there. Or just as likely (perhaps more so as the Wiki says Hobart is very sunny in summer), the single Hobart station has not moved, where in France we were seeing a combined focus on more airport percentage AND a concentration more southward, to more sunny places. So Hobart Airport may well be warming a bit in the summer sun, but no more than it was in 1970 so nothing changes.
In any case: I see no possible way for CO2 to warm the winters AND cool the summers. I see an easy way for a mild cooling trend to be swamped in winter by all the energy used at an Airport. Especially if the thermometer is near any heated buildings. Worse, I’d like to know how “global warming” makes winters warmer in Hobart, but summers warmer in Launceston. Nice “trick” that.
Global warming in Hobart? Humbug!