NOAA has put together a new series of surface stations called the
Reference Network (CRN) As a specialist in the technology of meteorology, I
like this program a lot. It takes great care to place emphasis on accuracy,
repeatability, linearity. and calibration of instruments. The best feature, as
far as I’m concerned is the use of three simultaneous aspirated and calibrated
air temperature probes, so that there is redundancy. And if one sensor starts
drifting it will show up against the data from the other two. Dr. Tom Karl from NCDC
deserves credit for bringing this project to implementation.
While this new instrumentation will ensure far more accurate in situ
measurements in the future, it will do little to help the disarray seen in the
surface temperature record of the past.
Here is the manual for it:
CRN Series December 10, 2002
X030 DCN 06
I want to bring attention to the way in which they rate weather station
locations, because it is very germane to the argument that some of the existing
USHCN and COOP stations have micro-site issues. As far as I know, no database
exists of the ratings below applied to the existing network of weather stations.
From the USHCRN manual:
The USCRN will use the classification scheme below to document the
"meteorological measurements representativity" at each site.
This scheme, described by Michel Leroy (1998), is being used by Meteo-France
to classify their network of approximately 550 stations. The classification
ranges from 1 to 5 for each measured parameter. The errors for the different
classes are estimated values.
- Class 1 – Flat and horizontal ground surrounded by a clear
surface with a slope below 1/3 (<19deg). Grass/low vegetation ground cover <10 centimeters high. Sensors
located at least 100 meters from artificial heating or reflecting surfaces, such as
buildings, concrete surfaces, and parking lots. Far from large bodies of water, except if it is
representative of the area, and then located at least 100 meters away. No shading when the sun
elevation >3 degrees.
- Class 2 – Same as Class 1 with the following differences.
Surrounding Vegetation <25 centimeters. Artificial heating sources within 30m. No shading for a sun elevation >5deg.
- Class 3 (error 1C) – Same as Class 2, except no artificial heating sources within 10 meters.
- Class 4 (error >= 2C) – Artificial heating sources <10 meters.
- Class 5 (error >= 5C) – Temperature sensor located next to/above
an artificial heating source, such a building, roof top, parking lot, or concrete surface."
One of the goals of the
www.surfacestations.org project, will be to apply this site classification
standard set forth by NOAA for the USCRN to the existing network of surface
stations so that the problems associated with some sites can be quantified, and
the good sites can be clearly defined as well. This will help scientists whom
use the surface temperature data do more accurate analyses.