Reconciliation of top-down and bottom-up CO2 fluxes in Siberian larch forest

Kumiko Takata, Prabir K. Patra, Ayumi Kotani, Junko Mori, Dmitry Belikov, Kazuhito Ichii, Tazu Saeki, Takeshi Ohta, Kazuyuki Saito, Masahito Ueyama, Akihiko Ito, Shamil Maksyutov, Shin Miyazaki, Eleanor J. Burke, Alexander Ganshin, Yoshihiro Iijima, Takeshi Ise, Hirokazu Machiya, Trofim C. Maximov, Yosuke NiwaRyo'Ta O'Ishi, Hotaek Park, Takahiro Sasai, Hisashi Sato, Shunsuke Tei, Ruslan Zhuravlev, Toshinobu Machida, Atsuko Sugimoto, Shuji Aoki

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


Carbon dioxide (CO2) fluxes by different methods vary largely at global, regional and local scales. The net CO2 fluxes by three bottom-up methods (tower observation (TWR), biogeochemical models (GTM), and a data-driven model (SVR)), and an ensemble of atmospheric inversions (top-down method, INV) are compared in Yakutsk, Siberia for 2004-2013. The region is characterized by highly homogeneous larch forest on a flat terrain. The ecosystem around Yakutsk shows a net sink of CO2 by all the methods (means during 2004-2007 were 10.9 g C m-2 month-1 by TWR, 4.28 g C m-2 month-1 by GTM, 5.62 g C m-2 month-1 and 0.863 g C m-2 month-1 by SVR at two different scales, and 4.89 g C m-2 month-1 by INV). Absorption in summer (June-August) was smaller by three bottom-up methods (ranged from 88.1 to 191.8 g C m-2 month-1) than the top-down method (223.6 g C m-2 month-1). Thus the peak-to-trough amplitude of the seasonal cycle is greater for the inverse models than bottom-up methods. The monthly-mean seasonal cycles agree among the four methods within the range of inter-model variations. The interannual variability estimated by an ensemble of inverse models and a site-scale data-driven model (the max-min range was 35.8 g C m-2 month-1and 34.2 g C m-2 month-1) is more similar to that of the tower observation (42.4 g C m-2 month-1) than those by the biogeochemical models and the large-scale data-driven model (9.5 g C m-2 month-1 and 1.45 g C m-2 month-1). The inverse models and tower observations captured a reduction in CO2 uptake after 2008 due to unusual waterlogging.

Original languageEnglish
Article number125012
JournalEnvironmental Research Letters
Issue number12
Publication statusPublished - 2017 Dec 15


  • Siberian larch forest
  • interannual variation
  • multi method comparison
  • net CO flux
  • seasonal cycle

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Environmental Science(all)
  • Public Health, Environmental and Occupational Health


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