OK, in a couple of prior postings we’d looked at some local airport and non-airport areas to see if airports were warmer. That was on a modestly sunny day in late summer / early fall ( October 2nd).
Then, we did, in fact, find airports were warmer. We also discovered that the ASOS automated airport temperature reporting gismos round temperatures UP in whole degrees of C so the ASOS tends to have a ‘jumpy’ graph that is typically higher than the “airport” at the same place (which looks to be a rounded degrees F data feed).
But this left open the question of “Why?”.
Was it the jets taking off?
The ground traffic and cars?
The tarmac and lack of ground cover?
Well, today in Silicon Valley it’s a wonderful mid-fall heavy overcast / high fog or low cloud kind of day with nearly zero wind. Exactly ZERO solar heating as of 8 am. But a load of airplanes will have taken off from the airport… A nice time to do a “Tarmac vs Jet Exhaust” examination.
So I’ve taken a look at our target sites.
Palo Alto Airport
Moffett Field Airport
San Jose International Airport
Reid Hillview Airport
and some nearby areas.
The “punch line” is that everything is more or less about 48 F. The one exception is Reid Hillview which is at 45 F. Odd that. But it is over near the western hills and on cold days we get colder air sinking down those hills that could easily be giving them a slower start to the daily warming.
Santa Clara is 48.9 F and is in a location near cars. San Jose Airport is 48 F and MKSJC (the ASOS at SJC) is 48 F. Palo Alto is 48 F and Moffet is 49 F (but given that Santa Clara is 48.9 F that looks like it’s inside the rounding jitter). A quick scan of the entire list of nearby stations shows them ranging mostly from about 47.x F to 51 F (tossing the highest and lowest couple as outliers). So it looks to me like we’ve got pretty much 49 F +/- 1.x F over the entire south bay, and it’s not significantly higher at the airports than it is anywhere else under still air and heavy overcast. (Remember that this whole area is just one giant Urban Heat Island in a bowl of mountains… so that the whole heat island is about the same is not surprising).
But what about the prior readings? They showed excess heat?
Well, that was on a day with sunshine…
So my conclusion is a pretty simple one: A few thousand feet on a side rectangle of black tarmac and concrete gets hotter in the sun than does a tree lined sub-urban neighborhood with lawns and sprinklers. It’s all about Tarmac vs Trees and the tendency of plants to thermo-regulate via transpiration. In short, it’s the Hydrological Cycle vs Tarmac Desert.
I’ll be keeping an eye on this as the day unfolds. Watching for morning commute impacts near Santa Clara. If we get some significant change of sunshine it will be interesting to see if there is ‘separation’ of the stations. But for now it’s pretty clear that we have a modestly uniform UHI in The Bowl, but when the sun shines, the black dry parts get hotter than the green damp ones.
Want to cure “Global Warming”? Move the thermometer from the airport to the city park…
Santa Clara. Away from the airport, but not so far for it to have different weather. And well inside the San Franciso Bay Area mountain ringed Urban Heat Island Bowl…
This is is a link to the Wunderground page for that site. The “history” button lets you get these graphs.
Next we have SJC. That is the airport proper at San Jose International:
This is is a link to the Wunderground page for that site. The “history” button lets you get these graphs.
Finally, we have the ASOS station.
This is is a link to the Wunderground page for that site.
A Chart of Temperatures Of The Moment
Between when I wrote the top part, and this moment, the ASOS has jumped from 48 F to 50 F, so one supposes that it ticked over a C boundary on the rounding…
ASOS_HFM SAN JOSE, CA, Santa Clara, CA 50.0 °F / 10 °C 43 °F / 6 °C 81% North at 0.0 mph / 0 km/h
30.15 in / 1020.9 hPa 0.00 in / 0 mm / hr 48 °F / 9 °C 55 ft 22 min 0 sec ago MADIS Website
APRSWXNET Santa Clara CA , Santa Clara, CA 47.0 °F / 8 °C 44 °F / 7 °C 90% ENE at 0.0 mph / 0 km/h
30.14 in / 1020.5 hPa 0.00 in / 0 mm / hr 47 °F / 8 °C 116 ft 7 min 24 sec ago MADIS Website
Santa Clara, CA 49.3 °F / 9 °C 46 °F / 8 °C 89% North at 0.0 mph / 0 km/h
30.10 in / 1019.2 hPa 0.00 in / 0 mm / hr 48 °F / 9 °C 12 ft 3 sec ago Rapid Fire
0.5 mi E of Homestead and Lawrence, Santa Clara, CA 50.2 °F / 10 °C 41 °F / 5 °C 70% North at 0.0 mph / 0.0 km/h / 0.0 m/s
30.00 in / 1015.8 hPa 0.00 in / 0 mm / hr 49 °F / 10 °C 140 ft 31 sec ago Normal Website
APRSWXNET Santa Clara CA , Santa Clara, CA 50.0 °F / 10 °C 46 °F / 8 °C 86% North at 0.0 mph / 0 km/h
30.12 in / 1019.9 hPa 0.00 in / 0 mm / hr – 137 ft 7 min 18 sec ago MADIS Website
Santa Clara – Lawrence & Monroe, Santa Clara, CA 49.6 °F / 9 °C 46 °F / 8 °C 88% NNW at 0.0 mph / 0 km/h
30.17 in / 1021.6 hPa 0.00 in / 0 mm / hr 49 °F / 10 °C 88 ft 1 sec ago Rapid Fire
Wooding and Spruance, San Jose, CA 48.7 °F / 9 °C 48 °F / 9 °C 98% WNW at 0.0 mph / 0.0 km/h / 0.0 m/s
29.83 in / 1010.0 hPa 0.00 in / 0 mm / hr 48 °F / 9 °C 0 ft 0 sec ago Rapid Fire
Starbush, Sunnyvale, CA 51.1 °F / 10 °C 38 °F / 3 °C 61% – at –
– – / hr – 75 ft 3 min 29 sec ago Normal
Birdland-Raynor, Sunnyvale, CA 49.1 °F / 9 °C 44 °F / 7 °C 82% NNE at 0.0 mph / 0.0 km/h / 0.0 m/s
30.11 in / 1019.5 hPa 0.00 in / 0 mm / hr 49 °F / 9 °C 180 ft 5 sec ago Rapid Fire
Saratoga Ave./Doyle Rd., San Jose, CA 49.7 °F / 9 °C 44 °F / 6 °C 80% North at 0.0 mph / 0.0 km/h / 0.0 m/s
30.14 in / 1020.5 hPa 0.00 in / 0 mm / hr 50 °F / 10 °C 190 ft 4 min 37 sec ago Normal
El Camino/Wolfe, Sunnyvale, CA 52.7 °F / 11.5 °C 45 °F / 7 °C 75% NE at 0.0 mph / 0.0 km/h / 0.0 m/s
29.94 in / 1013.8 hPa 0.00 in / 0 mm / hr – 90 ft 1 min 6 sec ago Normal Website
near eBay Headquarters, Campbell, CA 48.2 °F / 9 °C 47 °F / 8 °C 98% NNW at 0.0 mph / 0.0 km/h / 0.0 m/s
29.88 in / 1011.7 hPa 0.00 in / 0 mm / hr 48 °F / 9 °C 165 ft 3 sec ago Rapid Fire Website
Strawberry Gardens, Sunnyvale, CA 49.5 °F / 9 °C 44 °F / 7 °C 82% SSE at 0.0 mph / 0.0 km/h / 0.0 m/s
30.08 in / 1018.5 hPa 0.00 in / 0 mm / hr 49 °F / 10 °C 95 ft 5 min 37 sec ago Normal
Campbell Ave. and Foote St., Campbell, CA 50.0 °F / 10 °C 47 °F / 9 °C 90% North at 0.0 mph / 0 km/h
29.94 in / 1013.8 hPa 0.00 in / 0 mm / hr 50 °F / 10 °C 30 ft 0 sec ago Rapid Fire
Sunnyvale – Jasmine, Sunnyvale, CA 50.0 °F / 10 °C – 87% North at 0.0 mph / 0.0 km/h / 0.0 m/s
30.19 in / 1022.2 hPa 0.00 in / 0 mm / hr 50 °F / 10 °C 70 ft 3 min 47 sec ago Normal
Third and Campbell, Campbell, CA 49.1 °F / 9 °C 47 °F / 8 °C 93% SSW at 0.0 mph / 0.0 km/h / 0.0 m/s
0.00 in / 0.0 hPa 0.00 in / 0 mm / hr 49 °F / 9 °C 197 ft 1 sec ago Normal
APRSWXNET Sunnyvale CA , Sunnyvale, CA 50.0 °F / 10 °C 44 °F / 7 °C 80% NE at 0.0 mph / 0 km/h
30.17 in / 1021.6 hPa 0.00 in / 0 mm / hr – 127 ft 7 min 49 sec ago MADIS Website
Berryessa, San Jose, CA 48.0 °F / 8 °C 45 °F / 7 °C 92% South at 0.0 mph / 0.0 km/h / 0.0 m/s
30.13 in / 1020.2 hPa 0.00 in / 0 mm / hr 47 °F / 8 °C 131 ft 2 sec ago Normal Website
Comstock Ln and Park Wilshire Cr, San Jose, CA 47.3 °F / 8 °C 47 °F / 8 °C 98% ENE at 0.0 mph / 0.0 km/h / 0.0 m/s
30.06 in / 1017.8 hPa 0.00 in / 0 mm / hr 47 °F / 8 °C 188 ft 14 min 14 sec ago Normal
Purdue Drive, Saratoga, CA 48.9 °F / 9 °C 44 °F / 7 °C 86% West at 0.0 mph / 0.0 km/h / 0.0 m/s
30.12 in / 1019.9 hPa 0.00 in / 0 mm / hr 48 °F / 9 °C 242 ft 2 sec ago Rapid Fire
Near Saratoga and Cox, Saratoga, CA 52.2 °F / 11 °C 44 °F / 7 °C 79% SSE at 0.0 mph / 0.0 km/h / 0.0 m/s
30.14 in / 1020.5 hPa 0.00 in / 0 mm / hr – 165 ft 1 min 2 sec ago Normal
Near Westmont HS, San Jose, CA 49.0 °F / 9 °C 43 °F / 6 °C 83% WSW at 0.0 mph / 0 km/h
30.16 in / 1021.2 hPa – / hr 48 °F / 9 °C 260 ft 6 min 35 sec ago Normal
Homestead/Kennewick, Sunnyvale, CA 48.6 °F / 9 °C 46 °F / 8 °C 92% ENE at 0.0 mph / 0 km/h
30.24 in / 1023.9 hPa 0.00 in / 0 mm / hr 48 °F / 9 °C 225 ft 2 sec ago Rapid Fire
Rooftop – Larchmont Ave, Saratoga, CA 48.0 °F / 8 °C 44 °F / 7 °C 88% North at 2.0 mph / 3 km/h
29.78 in / 1008.4 hPa 0.00 in / 0 mm / hr 48 °F / 9 °C 301 ft 12 sec ago Normal
Graphs for Moffett, Palo Alto, and related
Well, as I type this, Palo Alto looks pretty grim. Like someone just turned the equipment on at 7 am when they showed up for work…
Moffett is a bit better and right next door.
Interesting to me that the “nearby” automated non-ASOS also is a bit ‘jumpy’ in the graph. More ’rounding up’ issues to find? Hmmm?…
I could not resist adding KCASUNNY4 just because of the name… Strawberry Gardens:
Then, a bit more up in the hills and a rich area with lots of lawn and trees, Los Altos:
Not enough to make a definitive “call” on a conclusion, but where this points me is to the idea that we have a few things interacting.
1) It’s the Tarmac. Sure, some planes taking off can add a touch more heat for a moment. If it happens at just the right time in just the right place for the wind to take it to the thermometer, might even add a touch for a day. Worth further study… BUT, the “big lump” is the acres of tarmac that don’t go away, even when planes do not fly. So AGW True Believers hollering about how few daily takeoffs and landings there are in the New Zealand airports have missed the point…
Furthermore, to the extent Svensmark is right, decreased cloud cover from cosmic rays during “warm times” will have an amplified impact at Airport Thermometers. Right at the time we moved most of the thermometers to Airports. (Can you say “crappy instrumentation decisions?… I knew you could…)
2) It’s the Vegetation. To the extent that we’ve gone to other recording sites and put them over gravel, stone, cement, tarmac, asphalt, bare dirt; and cut back the bushes, shrubs, trees, etc. what we’re finding is that those surfaces have ‘warmed’ relative to the natural flora that was there in 1800… Basically, ‘grooming’ the recording stations landscape is an error term. Having it near a paved access road is also an error term. Yet that is what we do to make things “neat”.
3) And it’s the sunshine interacting with those two things. See Svensmark…
4) The “new” equipment does ‘odd things’ to the graphs with step functions, rounding up, all sorts of “minor” oddities. Even in equipment other than the ASOS (see the APRS WX graph…) Since we’re supposed to panic over 1/100 C, how about we use the equipment that reports a smooth temperature graph without that rounding induced step function? It also means we need to audit exactly what equipment is used in each location, and how that has changed over time, and characterize the impact that the shift to automation has had on the end result. You simply can NOT change the thermometer that much in a calorimeter and not have something bad happen to your results. Go ask a chemist…
5) It is also pretty clear to me that anyone attempting to measure the ‘Airport Heat Island’ at their nearby airport simply MUST take into consideration the amount of sunshine they get. Testing at Phoenix will give a far different result than testing at London in the fog. Any study that found “no difference” and did not report the degree of sunshine during the test is in need of an overhaul. Still air and sun ought to give the strongest AHI while moving air and no sun ought to give the least (and rain / snow will likely dampen it as well ;-). Find a place where those conditions both happen and you can characterize the magnitude of the impact.
Bottom Line: Airports are a lousy place to measure “climate change” and will give “bogus high” temperatures AND “bogus high” trends over time. Yet that is where we now measure over 90% of our temperatures.
[Sidebar On Trends: The reason you will get bogus high TRENDS is two fold. The first, and simplest, is that airports grow over time. SJC was a grass field not all that long ago, in climate terms. It was a small ‘prop plane’ place in the 1960s and added some modest commercial traffic in the ’70s. But now it’s a giant wall to wall tarmac place with 2 international terminals. That is a common history for most airports.
The second is more subtle. You will find the AGW apologists constantly waving about “The Anomaly” as a talisman. And it is somewhat true that if you did anomalies as a single instrument compared only to itself (as it ought to be) you would remove a lot of error and bias. BUT (and it’s a very very big “But”…) that is not what they do.
First off, they change the hardware. So we now have automated things that do something different from what an old Liquid In Glass thermometer in a Stevenson screen did. An ‘anomaly’ between them is part temperature change and part instrument change. Oops… is that another Error Term I see? Yes, it is…
Then there are changes in process over time as well, so the temperatures “now” are differently handled from those “then”, so now you have a “Handling Charge” in your Error Terms as well.
Finally, they do “grid / box” anomalies in codes like GIStemp. Not “instrument to itself” anomalies. This is like comparing my 1967 VW to my present Mercedes and saying cars are going much faster now. An average of 4 thermometers in cow fields in 1850 in Santa Clara is simply NOT the same as an average of the thermometers at Moffett and SJC today. Making an “anomaly” out of those two averages simply tries to hide the stupidity of ignoring that they are measuring quite different places with quite different instruments and methods. Sweeping your Error Terms under the “grid / box” anomaly rug does not make them go away… ]