A theme in many recent posts has been whether the USHCN and NASA adjustments are successful in achieving their goals.
On a number of occasions, we’ve observed that the USHCN station history (SHAP) adjustment appears to be an odd statistical procedure and can be objectively seen to be unsuccessful in picking up recorded station moves. This issue was re-visited in connection with Lampasas TX, where a 2000 move to a non-compliant location was not identified and corrected for by the USHCN adjustment algorithm. In a post on Lampasas, I observed that the SHAP/FILNET algorithm seemed to have the effect of blending stations, in the following terms (though similar observations have been made on other occasions):
My impression of the impact of the SHAP/Filnet adjustments is that, whatever their stated intention, they end up merely creating a blend of good and bad sites, diluting the “good” sites with lower quality information from sites that are “bad” in some (objective) sense. When this version gets passed to Hansen, even his “unlit” sites no longer reflect original information, but are “adjusted” versions of unlit sites, in which it looks to me like there is blending from the very sites which are supposed to be excluded in the calculation.
Atmoz has now analyzed an arbitrary USHCN site (Saguache), mentioning Watts Up (but not CA), concluding:
In this post, I examined one surface station record to determine the effects of microsite bias. In doing so, I found that the SHAP adjustment as applied by NOAA does not account for all the station moves in the station history. A simple and tractable correction method is outlined in this case study which uses regional anomalies to correct stations for local effects.
This is the third occasion [Lampasas, TX; Miami, AZ] where SHAP corrections have been documented to not fully account for station moves. Furthermore, this analysis was done on a random station in the USHCN; it was not cherry-picked to prove a point. This suggests the SHAP algorithm does not correct for all microsite issues related to station moves. People using the SHAP-corrected data should be aware that not all microsite biases have been removed, and they should attempt to account for these issues themselves.
At this point, I’ve not evaluated whether Atmoz’ proposed method is more successful than the USHCN method. However, it’s nice that a third party has confirmed that the USCHN adjustment algorithm has failed to identify station moves – a point made here and at Watt’s Up, occasioning some unwarranted derision elsewhere.