Abstract
The northern wetland methane emission estimates have large uncertainties. Inversion models are a qualified method to estimate the methane fluxes and emissions in northern latitudes but when atmospheric observations are sparse, the models are only as good as their a priori estimates. Thus, improving a priori estimates is a competent way to reduce uncertainties and enhance emission estimates in the sparsely sampled regions. Here, we use a novel way to integrate remote sensing soil freeze/thaw (F/T) status from SMOS satellite to better capture the seasonality of methane emissions in the northern high latitude. The SMOS F/T data provide daily information of soil freezing state in the northern latitudes, and in this study, the data is used to define the cold season in the high latitudes and, thus, improve our knowledge of the seasonal cycle of biospheric methane fluxes. The SMOS F/T data is implemented to LPX-Bern DYPTOP model estimates and the modified fluxes are used as a biospheric a priori in the inversion model CarbonTracker Europe-CH4. The implementation of the SMOS F/T soil state is shown to be beneficial in improving the inversion model’s cold season biospheric flux estimates. Our results show that cold season biospheric CH4 emissions in northern high latitudes are approximately 0.60 Tg lower than previously estimated, which corresponds to 17% reduction in the cold season biospheric emissions. This reduction is partly compensated by increased anthropogenic emissions in the same area (0.23 Tg), and the results also indicates that the anthropogenic emissions could have even larger contribution in cold season than estimated here.
Highlights
In the northern high latitudes (NHL), there are vast wetland areas where over a quarter of the total soil carbon is stored [1,2]
The soil thawing happens almost reversely starting from the USA and the southern border of Eurasia around the New Year and occurring the latest in northeast
The shortest wintertime length is a couple of days and the longest wintertime lengths are over 220 days
Summary
In the northern high latitudes (NHL), there are vast wetland areas where over a quarter of the total soil carbon is stored [1,2]. In addition to storing a large amount of carbon, these wetlands are a large source of methane (CH4 ), which is the second most important anthropogenic greenhouse gas in terms of the radiative forcing [3]. The magnitude and seasonal cycle of NHL wetlands’ methane emissions are, highly uncertain [4,5], and climate change will likely affect ecosystem dynamics in the NHL wetlands, which could increase the methane emissions [6]. A well-known characteristic of NHL wetland methane emissions is their strong seasonal cycle. Methane fluxes are high when soil is moist and warm. The methane fluxes start to decrease when soil temperature decreases, and Remote Sens.
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call