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Was the Anchorage all-time temperature record aided by airport growth?

It sure seems that way. Yesterday, NWS Anchorage trumpeted these headlines:

Here is the official report. Interesting that they say here the old record was 77 in 1999 rather than 89 in 1969 in their tweets. Which is it?

Source: https://w2.weather.gov/climate/getclimate.php?wfo=pafc

The stage was set by a weather event: a large high-pressure dome centered squarely over Anchorage:

Upper-level high pressure is very strong and anchored over southern Alaska. Model output. (TropicalTidbits.com)

Despite what climate alarmists say, it was a weather event, not a climate event.

But did the location of the temperature reading have anything to do with the new “all-time” record high in Anchorage? Quite possibly.

First, there were other records set in the area, and all of them were smack-dab under the center of that high pressure dome. It is a well-known meteorological fact that sinking air heats up:

Note that those other records are all at airport locations.

Here’s the location of the ASOS (Aviation weather station) that made the Anchorage record in Google Earth. Note the black streaks on the runway just south, that’s where the majority of planes land and put on reverse thrust and take off. Winds coming from the south will push hot jet exhaust towards the ASOS temperature sensor.

The yellow marker is the location of the ASOS weather station via Google Earth:

Click to enlarge. Source: https://www.google.com/maps/@61.168541,-150.0165294,3320m/data=!3m1!1e3

NW winds will be warming downslope winds from Mt. Sustina (Foehn winds). Yesterday the prevailing winds were WEST at the time of the records, but NW either side of that hour. Winds from N, NW, W, SW, and S will all transport heat from the taxiway and runway asphalt towards the temperature sensor.

Closeup view:

Source: https://www.google.com/maps/@61.16908,-150.0275,245m/data=!3m1!1e3

This image from Bing Maps via Digital Globe shows that there is construction going at the airport for that runway. Note all the construction equipment parked around the ASOS station (circled in red):

Source: https://www.bing.com/maps?cp=61.16908018593092~-150.02875101566315&sty=r&lvl=18&FORM=MBEDLD

One wonders if the construction equipment might have been adding to the temperature record, like our famous Scottish Ice Cream Truck added to an “all-time” temperature record.

Here is the hourly data from July 4th:

Source: https://w1.weather.gov/data/obhistory/PANC.html

The Government Hill station in Anchorage , about 5.6 miles away to the NE, only hit 79 about the same time on July 4th

Source: https://www.wunderground.com/dashboard/pws/KAKANCHO105/graph/2019-07-4/2019-07-4/daily

In 1969, the airport station was not sandwiched between two ashpalt heatsinks and the ASOS didn’t exist. The ASOS system didn’t come into use until the 1990s.

I think the location at the airport could have easily added a couple of degrees to the record. Same for the other airport locations of Kenai, Palmer, and King Salmon.

Airport history, note the growth:

http://www.dot.state.ak.us/anc/about/history.shtml

It sure looked a lot different before 1970. Small tower, and only one runway, as this historical photo from the FAA shows, looking west:

Note the airport today – a lot of asphalt and concrete:

And in 1964, according to NOAA’s HOMR database, the station was moved about a mile west, probably from the tower location. Back then most small airport towers had the temperature sensor on the tower so they could computer and report the very important density altitude information.

Source: https://www.ncdc.noaa.gov/homr/#ncdcstnid=20022040&tab=LOCATIONS

This was probably due to the airport reconstruction due to the great Alaska Earthquake. Maybe the Earthquake had a hand in the 1969 record due to the location change and the construction.

In my view, the Anchorage airport is a false record, aided and abetted by the location of the thermometer, and a terrible place to measure for climatic records. In my view, this record reflects the growth of the airport, not climate change.

Don’t believe me? Read this recently released peer-reviewed paper which says thing like “openness” due to obstructions contribute as much as 1 degree C: (h/t to Dr. Roger Pielke Sr.)

Microscale Warming due to Poor Ventilation at Surface Observation Stations

Abstract

Screen-level air temperature measurements at surface observation stations are influenced by local-site-scale factors. These local influences may affect global-scale climate change studies. This study investigated the influence of surface obstacles on air temperature measurements at the screen level at climate observation stations in Japan. Screen-level air temperature was measured simultaneously at two neighboring sites (<100 m apart) that differed in terms of their openness. Daytime air temperature was 0°–1°C higher at the narrower site, and theoretical analysis revealed that this warming was caused by poor ventilation. At night, poor ventilation at the narrower site caused the air temperature to be 0°–0.2°C lower, which was demonstrated experimentally and by theoretical analysis. The range of temperature changes due to site narrowing shown in this study is not negligible in climate change studies. Guidelines for site maintenance and metadata recoding were consequently proposed in terms of site openness.

https://journals.ametsoc.org/doi/abs/10.1175/JTECH-D-18-0176.1

It makes me wonder if that construction machinery (see above in the Bing Maps photo) was still parked around the ASOS for the July 4th holiday.

via Watts Up With That?

https://ift.tt/2LBrvzr

July 5, 2019 at 12:26PM

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