Contrasting Regional Carbon Cycle Responses to Seasonal Climate Anomalies Across the East-West Divide of Temperate North America

B Byrne; J Liu; A A Bloom; K W Bowman; Z Butterfield; J Joiner; T F Keenan; G Keppel-Aleks; N C Parazoo; Y Yin

doi:10.1029/2020GB006598

Contrasting Regional Carbon Cycle Responses to Seasonal Climate Anomalies Across the East-West Divide of Temperate North America

Global Biogeochem Cycles. 2020 Nov;34(11):e2020GB006598. doi: 10.1029/2020GB006598. Epub 2020 Nov 13.

Authors

B Byrne¹, J Liu^{1

2}, A A Bloom¹, K W Bowman^{1

3}, Z Butterfield⁴, J Joiner⁵, T F Keenan^{6

7}, G Keppel-Aleks⁴, N C Parazoo¹, Y Yin²

Affiliations

¹ Jet Propulsion Laboratory California Institute of Technology Pasadena CA USA.
² Division of Geological and Planetary Sciences California Institute of Technology Pasadena CA USA.
³ Joint Institute for Regional Earth System Science and Engineering University of California Los Angeles USA.
⁴ Department of Climate and Space Sciences and Engineering University of Michigan Ann Arbor MI USA.
⁵ Laboratory of Atmospheric Chemistry and Dynamics NASA Goddard Space Flight Center Greenbelt MD USA.
⁶ Earth and Environmental Sciences Area Lawrence Berkeley National Laboratory Berkeley CA USA.
⁷ Department of Environmental Science, Policy and Management University of California Berkeley CA USA.

Abstract

Across temperate North America, interannual variability (IAV) in gross primary production (GPP) and net ecosystem exchange (NEE) and their relationship with environmental drivers are poorly understood. Here, we examine IAV in GPP and NEE and their relationship to environmental drivers using two state-of-the-science flux products: NEE constrained by surface and space-based atmospheric CO₂ measurements over 2010-2015 and satellite up-scaled GPP from FluxSat over 2001-2017. We show that the arid western half of temperate North America provides a larger contribution to IAV in GPP (104% of east) and NEE (127% of east) than the eastern half, in spite of smaller magnitude of annual mean GPP and NEE. This occurs because anomalies in western ecosystems are temporally coherent across the growing season leading to an amplification of GPP and NEE. In contrast, IAV in GPP and NEE in eastern ecosystems is dominated by seasonal compensation effects, associated with opposite responses to temperature anomalies in spring and summer. Terrestrial biosphere models in the MsTMIP ensemble generally capture these differences between eastern and western temperate North America, although there is considerable spread between models.

Keywords: North America; carbon cycle; gross primary production; interannual variability; net ecosystem exchange; terrestrial biosphere model.