| Summary: | This study compares the CH 4 fluxes from two arctic wetland sites of different annual temperatures during 2004 to 2006. The PEATLAND-VU model was used to simulate the emissions. The CH 4 module of PEATLAND-VU is based on the Walter-Heimann model. The first site is located in northeast Siberia, Indigirka lowlands, Kytalyk reserve (70° N, 147° E) in a continuous permafrost region with mean annual temperatures of −14.3°C. The other site is Stordalen mire in the eastern part of Lake Torneträsk (68° N, 19° E) ten kilometres east of Abisko, northern Sweden. It is located in a discontinuous permafrost region. Stordalen has a sub arctic climate with a mean annual temperature of −0.7°C. Model input consisted of observed temperature, precipitation and snow cover data. In all cases, modelled CH 4 emissions show a direct correlation between variations in water table and soil temperature variations. The differences in CH 4 emissions between the two sites are caused by different climate, hydrology, soil physical properties, vegetation type and NPP. For Kytalyk the simulated CH 4 fluxes show similar trends during the growing season, having average values for 2004 to 2006 between 1.29–2.09 mg CH 4 m −2 hr −1 . At Stordalen the simulated fluxes show a slightly lower average value for the same years (3.52 mg CH 4 m −2 hr −1 ) than the observed 4.7 mg CH 4 m −2 hr −1 . The effect of the longer growing season at Stordalen is simulated correctly. Our study shows that modelling of arctic CH 4 fluxes is improved by adding a relatively simple hydrological model that simulates the water table position from generic weather data. Our results support the generalization in literature that CH 4 fluxes in northern wetland are regulated more tightly by water table than temperature. Furthermore, parameter uncertainty at site level in wetland CH 4 process models is an important factor in large scale modelling of CH 4 fluxes.
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