When is a USHCN airport station not at the airport?

In his early 60’s schtick “Hippy Dippy Weatherman” comic George Carlin used to say “Why do they always give the temperature at the airport? Nobody lives there!”

In the case of the airport weather station in Susanville, CA, he’d be right. Here’s the airport station:

Only one problem. Even though NCDC’s metadatabase and GISS both label this Station as “Susanville Airport”…

…the station at the airport above is not the USHCN station. This is something we discovered in quality control for our recent paper.The first clue? The lat/lon of 40.4167, -120.6631 isn’t anywhere near the airport, but at the Lassen County Courthouse downtown. WUWT?

What’s even more odd is that the alternate name is “Susanville 2SW”. This generally means the station is two miles southwest of the U.S. Post office in the center of town, an old locator method employed by NCDC for a very long time. But that isn’t anywhere close either. This weekend I figured out the puzzle with a road trip. 

In the NCDC metadatabase equipment list, they show that the station is MMTS based, and not using airport equipment:

But they show this station as having an airport identifier:

I did my preliminary work to locate the actual station using the lat/lon and the location cues which said “Sheriff’s office” so this courthouse location made sense:

So I programmed my GPS, I set off last Saturday afternoon, fully expecting to find the USHCN station there. Boy was I wrong.

After about a half hour of searching, I couldn’t find any evidence of the equipment. I even went up the hill behind the courthouse to get a vantage point so I could look at the roof with binoculars to see if the MMTS and rain gauge were on the roof. No luck.

There were no Sheriff cars parked at the substation behind the courthouse, but that isn’t unusual for a weekend and many deputies take the cars home. So I was stumped. I decided to head back to the airport for a look just in case it was maybe near the flight services office building. No luck there.

Thank goodness for free WiFi. I decided to try some searching at the local McDonald’s which offers free WiFi.

Searches for the NCDC B91 forms were no help either. Two stations showed, one current (the one I was seeking) and one that was closed:

And the B91 report simply said “Sheriff’s Dept”:

Susanville CA B91 Feb 2011 (PDF)

Great. I was stumped. Had the station recently closed maybe? There was no indication as such in any of the NCDC metadata, it all said “current”. There were no recent lat/lon changes either.

However there was one clue in the description. While both the old and new descriptions fit the courthouse location indicated by the most current lat/lon, and the courthouse is in fact near the northwest edge of the city, something didn’t seem quite the same in the two descriptions:

So I decided I’ll go back to basics, and simply Google “Lassen County Sheriff’s Department”. This is what came up:

Hmmm. Clicking on the GE marker led me to wholly different place about a mile northeast of the courthouse. I reprogrammed my GPS and set off for the new location.

Eureka, I found it:

Note the a/c heat exchanger and the backup generator. But of even greater concern was all the standing water in the ditch full of cattails near the MMTS. Note the lush lawn:

Susanville is generally considered “arid”, and almost desert. When you look at the location NOAA has a rule in the observing handbook that we cited in our recent paper:

Fall, S., A. Watts, J. Nielsen-Gammon, E. Jones, D. Niyogi, J. Christy, and R.A. Pielke Sr., 2011: Analysis of the impacts of station exposure on the U.S. Historical Climatology Network temperatures and temperature trends. J. Geophys. Res., 116, D14120, doi:10.1029/2010JD015146.Copyright (2011) American Geophysical Union.

National Weather Service Observing Handbook No. 2 [National Weather Service (NWS), 1989, p. 46], which states that “The equipment site should be fairly level, sodded, and free from obstructions (exhibit 5.1). It should be typical of the principal natural agricultural soils and conditions of the area…

Hmmm, from the air, it doesn’t look that typical or representative to me:

Big patch of green and parking lot in the middle of an arid landscape.

And compared to the original airport location shown in the photo at top? Lawns versus dry scrub. Big change.

After doing all my photos and GPS reading, I wrote my report yesterday. Here’s the results. The station has been moved a fair amount, and the metadata and NCDC’s metadatabase does not reflect the most recent move. The lat/lon published there is from the second location. Here’s the location chronology mapped on Google Earth:

Here’s my report, and the explanation for how the station ceased to be located at the airport. The difference was the equipment, AWOS versus ASOS:

Site Survey

Susanville, CA USHCN COOP NUMBER: 048702

Location at Sheriff’s office at north edge of town, near the jail. 1415 Sheriff Cady Lane, Susanville, CA 96130

Survey By: Anthony Watts 08/13/11 at 2:30PM

USHCN Reported Coordinates of Site: Susanville AP (40.4167, -120.6631, 4184feet 1263m)

Measured GPS Coordinates of site: Lat./Long. 40.425298, -120.649119 Elevation 4211 feet 1283m

Site description and known history:

The MMTS sensor and rain gauge are located southwest (~30 feet) of the main Sheriff’s office building on an irrigated lawn. The MMTS temperature sensor is within 5 feet of a drainage ditch that has a significant stand of cattails in the summer, indicating year round water, likely runoff from lawn irrigation. A large asphalt parking lot and administrative building is approximately 70 feet to the west of the sensor. Another concrete walkway and parking lot is approximately 100 feet east of the sensor. An asphalt roadway is approximately 80 feet to the south of the sensor.

Curator Notes:

The current site manager is the Lassen County Sheriff’s office. The sensors were changed from CRS/LIG thermometers on October 24th 1996 to MMTS when the station was moved to the Sheriff’s office near the courthouse. The station was moved to this location because the Susanville airport weather observation system was upgraded by the FAA to an AWOS system, which is not as full featured as ASOS and does not report to the NOAA weather wire for regular surface observations as ASOS equipment does.

On March 15^th 2004, the station was moved to the new Sheriff’s office north of town near the jail.

See Google Earth Map of all three locations.

Site Survey Notes:

1. The lawn was well watered and well trimmed. This indicates a possibility of induced moist enthalpy bias in Tmin which is sensitive to increased nighttime humidity

2. Standing water observed in the nearby drainage ditch with cattails, downslope from sensor, indicating excess water drainage is likely.

3. A/C heat exchanger observed operating at SW corner of building ~30 feet away.

4. Name of station remains as “Susanville Airport” in NCDC database even though the USHCN station has not been located there since 1996.

I don’t blame volunteer Russ Steele for the misidentification of the station in his initial survey. Back then, metadata was even worse than it is now, and all indications then (and now from the name) is that the station was at the airport. A simple administrative decision by the FAA to deploy AWOS instead of a full ASOS station resulted in this entire USHCN station move debacle.

The difference is summed up here, red highlight mine:

The Automated Weather Observing System (AWOS) units are operated and controlled by the Federal Aviation Administration (FAA) in the United States, as well as by state and local governments and some private agencies; the American National Weather Service (NWS) and Department of Defense (DOD) play no role in their operation or deployment.

These systems are among the oldest automated weather stations and predate ASOS. They generally report at 20-minute intervals and do not report special observations for rapidly changing weather conditions. There are several varieties of AWOS depending upon the sensor systems which are installed; the most common type is the AWOS-III, which observes temperature and dewpoint in degrees Celsius, wind speed and direction in knots, visibility, cloud coverage and ceiling up to twelve thousand feet, and altimeter setting. Recently, additional sensors which have become available for AWOS systems include present weather, freezing rain, and thunderstorm (lightning).

The Automated Surface Observing System (ASOS) units are operated and controlled cooperatively in the United States by the NWS, FAA and DOD. After many years of research and development, the deployment of ASOS units began in 1991 and was completed in 2004.

These systems generally report at hourly intervals, but also report special observations if weather conditions change rapidly and cross aviation operation thresholds. They generally report all the parameters of the AWOS-III, while also having the additional capabilities of reporting temperature and dewpoint in degrees Fahrenheit, present weather, icing, lightning, sea level pressure and precipitation accumulation.

Besides serving aviation needs, ASOS serves as a primary climatological observing network in the United States, making up the first-order network of climate stations. Because of this, not every ASOS is located at an airport; for example, one of these units is located at Central Park in New York City and another is located on Cabbage Hill near Pendleton, Oregon, for the sole purpose of providing climatological observations.

Mystery solved, and the surfacestations.org database has been properly updated with the correct station metadata and photos.

The temperatures between 2007 and 2011 at GISS, well that’s another mystery:

2007:

2011: