The Hockey Schtick:
A paper published today in Theoretical and Applied Climatology finds that the data homogenization techniques commonly used to adjust temperature records for moving stations and the urban heat island effect [UHI] can result in a “significant” exaggeration of warming trends in the homogenized record.
According to the authors, “Our analysis shows that “data homogenization for [temperature] stations moved from downtowns to suburbs can lead to a significant overestimate of rising trends of surface air temperature.”
The paper corroborates the prior work of Anthony Watts, Joseph D’Aleo, et al, finding leading meteorological institutions in the USA and around the world have so systematically tampered with instrumental temperature data that it cannot be safely said that there has been any significant net “global warming” in the 20th century.
Theoretical and Applied Climatology February 2014, Volume 115, Issue 3-4, pp 365-373,
Effect of data homogenization on estimate of temperature trend: a case of Huairou station in Beijing Municipality
Daily minimum temperature (Tmin) and maximum temperature (Tmax) data of Huairou station in Beijing from 1960 to 2008 are examined and adjusted for inhomogeneities by applying the data of two nearby reference stations. Urban effects on the linear trends of the original and adjusted temperature series are estimated and compared. Results show that relocations of station cause obvious discontinuities in the data series, and one of the discontinuities for Tmin are highly significant when the station was moved from downtown to suburb in 1996. The daily Tmin and Tmax data are adjusted for the inhomogeneities. The mean annual Tmin and Tmax at Huairou station drop by 1.377°C and 0.271°C respectively after homogenization. The adjustments for Tmin are larger than those for Tmax, especially in winter, and the seasonal differences of the adjustments are generally more obvious for Tmin than for Tmax. Urban effects on annual mean Tmin and Tmax trends are −0.004°C/10 year and −0.035°C/10 year respectively for the original data, but they increase to 0.388°C/10 year and 0.096°C/10 year respectively for the adjusted data. The increase is more significant for the annual mean Tmin series. Urban contributions to the overall trends of annual mean Tmin and Tmax reach 100% and 28.8% respectively for the adjusted data. Our analysis shows that data homogenization for the stations moved from downtowns to suburbs can lead to a significant overestimate of rising trends of surface air temperature, and this necessitates a careful evaluation and adjustment for urban biases before the data are applied in analyses of local and regional climate change
Temperature sensors were purposefully put near heat sources.
Not always, Smorg.
In some cases a temperature data collection station was put in a perfectly proper spot…..only to have heat sources built up around it over months and years.
Decades ago I used to see one in a field.
About 20 years ago the field was paved with asphalt.
The station was kept despite the heat rising from the black top.
After the parking spaces were painted on, a freshly-parked car or truck would sit right next to the data collector, it’s still-hot engine causing another rise in it’s temps.
When I left CA, that data station was still there.
There’s a part of undeveloped land not too far from it where it could have been moved, but it never was.
@Nanny G: #2
There are always exceptions, but there are also pictures of weather stations put in open areas, but a very wide sidewalk was put up to it, even though the stations aren’t checked very often, and a narrow sidewalk would have worked OK. I don’t know how often they are checked, but when they are, you would think that the person checking them would report the added construction around them, especially the ones that are near air conditioners or other hear sources. Some are even on top of businesses, the hottest part of the building.