Early in the project, one of the criticisms heard against the surfacestations.org effort was that there had been “cherry picking” going on in the selections of stations to survey, and that the project wasn’t reaching a wide area. In this first map of it’s kind, one can clearly see the how the quality distribution of the 460 out of 1221 stations surveyed so far looks and that those claims weren’t valid. The results clearly show that the majority of USHCN stations surveyed so far have compromised measurement environments. The question then is this; have these mircosite biases been adequately accounted for in the surface temperature record?
As you can see below, there appears to be some clustering near population areas, and some east coast/west coast volume bias. There are sparse areas in the midwest that I hope can be surveyed soon. But, there is a nationwide distribution. The thing that really stands out though is that there are few sites that are CRN1/2 and many more that are CRN 3/4/5. This speaks to the concerns that our measurement network is broadly affected by microsite biases and urbanization encroachment.
Here is how this map came about; there was a suggestion made in comments by Henry, suggesting that a map showing distribution of the CRN rating would be useful. I agreed, but lamented that I’m overloaded with work at the moment. The beauty though of this project is it’s capable volunteers.
Volunteer Gary Boden came to the rescue, and provided the map below as a function of the Excel spreadsheet tracking the ratings that I’ve made publicly available for some time now. You can download my data set in Excel format at www.surfacestations.org See his plot below:
Click picture for a larger image
Here is the same data presented in Pie Chart Form:
For reference, as originally defined in the NOAA Climate Reference Network Handbook, here are the site quality rating descriptions:
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. No 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 as a building, roof top, parking lot, or concrete surface.
Given that the generally agreed upon rise in surface temperature over the last century is approximately 0.8 degrees Centigrade, and seeing that the majority of climate monitoring stations have errors that are nearly equal to or larger than that value, the microsite bias errors are a cause for concern.
We need more stations surveyed; this upcoming Christmas travel season would be a perfect opportunity to help us fill in the midwest. If you’d like to volunteer and survey a station or two, visit www.surfacestations.org and sign up.