Part I and II of this series of weblogs (see and see), discussed the serious limited value of the use of a global average surface temperature anomaly to diagnose the global radiative imbalance (i.e., global climate heat system changes), and of a warm bias in the diagnosis of a global average surface temperature trend when the minimum temperatures are used in its construction.
In Part III, we discuss yet another serious issue that we raised in our paper
Pielke Sr., R.A., C. Davey, D. Niyogi, S. Fall, J. Steinweg-Woods, K. Hubbard, X. Lin, M. Cai, Y.-K. Lim, H. Li, J. Nielsen-Gammon, K. Gallo, R. Hale, R. Mahmood, S. Foster, R.T. McNider, and P. Blanken, 2007: Unresolved issues with the assessment of multi-decadal global land surface temperature trends. J. Geophys. Res., 112, D24S08, doi:10.1029/2006JD008229,
where we report,
Major problems with the microclimate exposure of a subset of surface Historical Climate Network (HCN) sites have been photographed Easterling et al. 1996; Davey and Pielke 2005]. The temperature instruments that are used in the HCN are often sited close to buildings, under trees, and near other local influences on the microclimate. These microclimate influences also change over time.”
The issue of the spatial and temporal representation of the temperature data that is collected is so fundamental that it is a scandal for any climate assessment that constructs a global average surface temperature to ignore this issue.
Anthony Watts has, therefore, provided us a critically important study to document these surface temperature measurement sites, since the US government agency tasked with this responsibility (the National Climate Data Center; NCDC) has refused to provide this photographic documentation, despite information that they actually have accomplished this task (the implication is that they are too embarrassed to show them to the public).
The extensive photographic library already completed under the direction of Anthony Watts with his volunteers can be accessed at “Weather Stations”. This a rich source of information, and I urge readers of Climate Science to access his website.
Two further excellent examples of further analysis of the issue of poor station exposure can be read at
Mahmood, Rezaul , Stuart A. Foster, and David Logan, 2006: The Geoprofile metadata, exposure of instruments, and measurement bias in climatic record revisited International Journal of Climatology
and
Brooks, Ashley Victoria. M.S., Purdue University, May, 2007. Assessment of the Spatiotemporal Impacts of Land Use Land Cover Change on the Historical Climate Network Temperature Trends in Indiana. Major Professors: Dev Niyogi and Michael Baldwin.
The message from these analyses is that the use of the surface temperature record from such observation sites to construct regional-, zonal- and global- averages introduces a bias (which is expected to be a significant warm bias) of an unknown magnitude. That this issue has not been questioned in the climate assessments nor by most of the media reports of the assessments is a scandal.
The conclusions we have reached with respect to the poor siting of the surface temperature measurement sites, for use in multi-decadal trend assessments, include:
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the poorly sited locations can not be “corrected” by using nearby better sited locations in order to provide added sources of independent data; see Pielke Sr., R.A. J. Nielsen-Gammon, C. Davey, J. Angel, O. Bliss, N. Doesken, M. Cai., S. Fall, D. Niyogi, K. Gallo, R. Hale, K.G. Hubbard, X. Lin, H. Li, and S. Raman, 2007: Documentation of uncertainties and biases associated with surface temperature measurement sites for climate change assessment. Bull. Amer. Meteor. Soc., 88:6, 913-928., where we concluded that“The use of temperature data from poorly sited stations can lead to a false sense of confidence in the robustness of multidecadal surface air temperature trend assessments”.
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The serious problem with poor sited surface temperature stations is a worldwide problem, based on our sampling so far (e.g., see for Mongolia and see for a range of locations around the globe).
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The World Meteorological Organization and the National Climate Date Center have been derelict in obtaining photographic documentation of these observing sites.
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Readers of Climate Science are encouraged to photograph the surface temperature sites in their country of residence, that are used to construct the land based contribution to the global average surface temperature anomalies, and send to Anthony Watts in be included in his very important (and essential) archiving of this information (his website for this is Watts Up With That and at Anthony Watt’s Searchable Online Data Base ).