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The TGS 2600 was the first low-cost solid-state sensor that shows a response to ambient levels of CH4 (e.g., range ≈1.8 –2.7 µmolmol-1). Here we present an empirical function to correct the TGS 2600 signal for temperature and (absolute) humidity effects and address the long-term reliability of two identical sensors deployed from 2012 to 2018. We assess the performance of the sensors at 30 min resolution and aggregated to weekly medians. Over the entire period the agreement between TGS-derived and reference CH4 mole fractions measured by a high-precision Los Gatos Research instrument was R2=0.42 , with better results during summer (R2=0.65 in summer 2012). Using absolute instead of relative humidity for the correction of the TGS 2600 sensor signals reduced the typical deviation from the reference to less than ±0.1 µmolmol-1 over the full range of temperatures from -41 to 27 ∘C. At weekly resolution the two sensors showed a downward drift of signal voltages indicating that after 10–13 years a TGS 2600 may have reached its end of life. While the true trend in CH4 mole fractions measured by the high-quality reference instrument was 10.1 nmolmol-1yr-1 (2012–2018), part of the downward trend in sensor signal (ca. 40 %–60 %) may be due to the increase in CH4 mole fraction because the sensor voltage decreases with increasing CH4 mole fraction. Weekly median diel cycles tend to agree surprisingly well between the TGS 2600 and reference measurements during the snow-free season, but in winter the agreement is lower. We suggest developing separate functions for deducing CH4 mole fractions from TGS 2600 measurements under cold and warm conditions. We conclude that the TGS 2600 sensor can provide data of research-grade quality if it is adequately calibrated and placed in a suitable environment where cross-sensitivities to gases other than CH4 are of no concern. [ABSTRACT FROM AUTHOR]

The TGS 2600 was the first low-cost solid state sensor that shows a weak response to ambient levels of CH4 (e.g., range ≈1.8-2.7 ppm). Here we present an empirical function to correct the TGS 2600 signal for temperature and (absolute) humidity effects and address the long-term reliability of two identical sensors deployed from 2012 to 2018. We assess the performance of the sensors at 30-minute resolution and aggregated to weekly medians. Over the entire period the agreement between TGS-derived and reference CH4 concentrations measured by a high-precision Los Gatos Research instrument was R2 = 0.42, with better results during summer (R2 = 0.65 in summer 2012). Using absolute instead of relative humidity for the correction of the TGS 2600 sensor signals reduced the typical deviation from the reference to less than ±0.1 ppm over the full range of temperatures from −41 °C to 27 °C. At weekly resolution the two sensors showed a downward drift of signal voltages indicating that after 10-13 years a TGS 2600 may have reached its end of life. While the true trend in CH4 concentrations measured by the high-quality reference instrument was 10.1 ppb yr−1 (2012-2018), part of the downward trend in sensor signal (ca. 40-60%) may be due to the increase in CH4 concentration, because the sensor voltage decreases with increasing CH4 concentration. Weekly median diel cycles tend to agree surprisingly well between the TGS 2600 and reference measurements during the snow-free season, but in winter the agreement is lower. We suggest developing separate functions for deducing CH4 concentrations from TGS 2600 measurements under cold and warm conditions. We conclude that the TGS 2600 sensor can provide data of research-grade quality if it is adequately calibrated and placed in a suitable environment where cross-sensitivities to gases other than CH4 is of no concern. [ABSTRACT FROM AUTHOR]

The article presents a study which investigates the performance of a low-cost methane (CH4) sensor in measuring the ambient air concentrations in the low arctic in Toolik Lake, Alaska. The study uses the Taguchi Gas Sensor (TGS) 2600 to detect the air contaminants, such as those typical for cigarette smoke. Results show that a high sensitivity for relative humidity and temperature similar to that expected from the specifications was revealed by TGS 2600.

Biome differences in surface energy balance strongly affect climate. However, arctic vegetation is considered sufficiently uniform that only a single arctic land surface type is generally used in climate models. Field measurements in northern Alaska show large differences among arctic ecosystem types in summer energy absorption and partitioning. Simulations with the Arctic Regional Climate System Model demonstrate that these variations in land surface parameters and ecological processes cause variation in surface fluxes that is sufficiently large to affect the regional climate. Plausible changes in arctic vegetation in response to high-latitude warming would feed back positively to local summer warming. This local warming could extend into the boreal zone. Climate feedbacks that operate during the growing season are particularly likely to impact vegetation and ecosystem properties. These field and model results suggest that vegetation changes within a biome could be climatically important and warrant consideration in regional climate modeling. [ABSTRACT FROM AUTHOR]

Presents research which showed that rapid changes to ecosystem processes will be superimposed upon and modulated by differences in substrate pH. Studies of trace-gas flux in the Arctic; Factors in land-atmosphere exchange; Soil pH boundary along the Arctic Foothills, Alaska, separating ecosystems; Traits of non-acidic tundra.