WUWT readers may recall last summer when the ASOS weather station at the Honolulu Airport malfunctioned, giving a whole series of shonky readings that resulted in a string of new record high temperatures being set. What was even worse, is that NOAA, knowing the records were based on faulty equipment, let them stand anyway even when a nearby NOAA station demonstrated the records were false.
WUWT reader “Geo” alerted me to the issue at DCA in “tips and notes”, and I made some immediate screencaps of the data which I have below. The DCA ASOS station at Washington National/Reagan Airport is part of the COOP A network which makes climate observations. First, a look at the station itself.
By siting standards, it at first glance appears to be well sited, being over 100 meters from the nearest runway, in the grass, and on the bayside riverside:
But on closer inspection it appears to be sited over asphalt:
From the ground, NOAA has this photo and more:
Here’s the hourly data in question, note the big jump at midnight and the 87.1F recorded at the 6 hour preceding mark. What’s odd about it is that its a big jump compared to the readings in the hour before and after, plus it occurred during thunderstorms and light rain. It seems unlikely.
Nearby Andrews AFB, just a few miles away, doesn’t show a similar jump in readings. It shows 64F and light rain at midnight, and a 6 hour max of 73F.
The high 87.1F reading at DCA made it into the official climatological report for Friday May 28th, which places it at 12:25AM, in the middle of rain and thunderstorms. It seems pretty clear that the reading is erroneous.
I recorded all the screen caps above last Friday, May 28th. I figured I’d wait to see if the NWS staff caught this and corrected it.
Sure enough, they did:
That’s the right way to do it. But is the 76F reading at 127AM valid? With a malfunctioning sensor, who knows for sure?
Now the question is: why does one NWS office fix an obviously faulty ASOS reading in the climate record while another ignores it and leaves it as a new record? Are there not standards for handling such things organization wide?
Another question is: how many events like this go undetected due to a lesser, non obvious magnitude, and remain in the climatic record?
And yet, there has been a large migration of GHCN to airport systems both in the US and globally.
At ICCC4, Apollo 17 astronaut and geologist Harrison Schmitt came up to me after my talk to tell me that I was “spot on” with criticizing the use of airport sensors for climate, because they were designed for a different mission. It was a proud moment for me, having watched this man walk the moon as a boy in high school. He said to me (and I’m going on recollection):
“The only purpose of the ASOS system is to measure the runway conditions for flight safety. I’ve seen runway temperatures vary as much as ten degrees from other airport locations. These shouldn’t be used for climate.”
The data at Reno, NV airport, showed not just siting differences, but a UHI factor also.
I agree with Dr. Schmitt’s assertion, and given that ASOS continues to produce faulty data, perhaps it is time to look at ASOS data issues on a broader scale.