How can two stations less than 1/2 mile apart be so different? How can one set a new record and best it by two degrees while the other doesn’t?
I was intrigued by this Record Event Report out of Las Vegas today because of the mercury reading, specifically in the “town” of Mercury:
Hmm, smashing. 113°F seemed high to me, since I was monitoring the state of the art NOAA Climate Reference Network Station in Mercury, NV earlier in the day I was surprised to see that value. I looked up the Mercury Desert Rock airport, and sure enough, there was 113°F. But, there was also another value.
Upon checking the data from the nearby Climate Reference Network station, I discovered that the highest temperature recorded there was only 110°F
The CRN monthly report says 111°F, so the high must have been very brief to not be captured in the 5 minute CRN data above.
When I say it is a nearby station, I really mean it. It is only 2164 feet (0.41 mile) away as I demonstrate on this Google Earth image:
I double checked the image by zooming in to be sure both stations are actually there, and they are. The signature of the ASOS aviation weather station is clearly visible as is the signature of the CRN station.
So what do we have here?
- Two stations separated by 2164 feet, both are “official” stations operated by NOAA.
- One station, the KDRA ASOS is designated for aviation purposes, but used for daily climate records. It has a single sensor, with a known history of problems. It is also near a big chunk of asphalt tarmac with an albedo different from the rest of the desert floor.
- The other station, the MRYN2 CRN is a Climate Reference network station, has state of the art sensors, including triple redundant temperature sensors, with automatic quality control, is placed specifically to be away from influences such as asphalt tarmac, and is surrounded by albedo matching the desert floor.
- The elevations are nearly identical with the airport ASOS station at 3238 feet and the CRN station at 3295 feet. That difference of 57 feet won’t amount to any appreciable delta in temperature due to the lapse rate.
- The temperature difference at the time the ‘record temperature” of 113°F is recorded at KDRA is two degrees. The CRN station is at 111°F.
So which one is the real temperature? I suppose it is a case of which one gets used for the “official” official reading, in which case is the warmer KDRA ASOS station.
The nearby CRN station does call the KDRA station data into question, but the horse has already left the barn now that NWS has released the numbers to the media. I will lodge a request with NWS Las Vegas to have them look at Mercury ASOS system though in case it is on the fritz as so many often do.
Oddly, after spending millions of dollars on the Climate Reference Network, the old COOP and ASOS network still gets used for high and low climate records.
Preserved data: (PDF files)