New paper finds some Antarctic temperature measurements show false warming of up to 10°C (18°F)

A paper published today in the Journal of Atmospheric and Oceanic Technology finds that temperature measurements on the Antarctic plateau "are shown to be significantly warm biased by solar radiation," resulting in temperature measurements up to 10°C (18°F) warmer than actual temperatures. The authors find that the summer Sun heats the housing for the electronic thermometers causing the warming bias during summer, which is also exacerbated by low wind conditions. Surface temperature measurements are particularly important at the poles, because satellite measurements of temperature do not include data poleward of 82.5° North and 70° South and the only available measurements in these areas are from surface temperature stations. Considering the tiny change in global temperature over the past 161 years of only 0.7°C, this newly-discovered large warming bias of up to 10°C calls into question data from areas critical to the AGW debate.

Journal of Atmospheric and Oceanic Technology 2011 ; e-View

Atmospheric temperature measurements biases on the Antarctic plateau

Christophe Genthon¹, Delphine Six, Vincent Favier

Laboratoire de Glaciologie et Géophysique de l'Environnement, CNRS/UJF, Saint Martin, d'Hères, France

Matthew Lazzara, Linda Keller

Antarctic Meteorological Research Center, University of Wisconsin-Madison, Madison, USA

Abstract

Observations of atmospheric temperature made on the Antarctic plateau with thermistors housed in naturally (wind) ventilated radiation shields are shown to be significantly warm biased by solar radiation. High incoming solar flux and high surface albedo result in radiation biases in Gill (multiplate) styled shields that can occasionally exceed 10°C in summer in case of low wind speed. Although stronger and more frequent when incoming solar radiation is high, biases exceeding 8°C are found even when solar is less than 200 Wm⁻². Comparing with sonic thermometers, which are not affected by radiation but which are too complex to be routinely used for mean temperature monitoring, commercially available aspirated shields are shown to efficiently protect thermistor measurements from solar radiation biases. Most of the available in situ reports of atmospheric temperature on the Antarctic plateau are from automatic weather stations that use passive shields and are thus likely warm biased in the summer. In spite of low power consumption, deploying aspirated shields at remote locations in such a difficult environment may be a challenge. Bias correction formulae are not easily derived and are obviously shield dependent. On the other hand, because of a strong dependence of bias to wind speed, filtering out temperature reports for wind speed less than a given threshold (about 4–6 ms⁻¹ for the shields tested here) may be an efficient way to quality control the data, albeit at the cost of significant data loss and records biased towards high wind speed cases.