Open AccessA model‐data intercomparison of CO 2 exchange across North America: Results from the North American Carbon Program site synthesis
Author(s) -
Schwalm Christopher R.,
Williams Christopher A.,
Schaefer Kevin,
Anderson Ryan,
Arain M. Altaf,
Baker Ian,
Barr Alan,
Black T. Andrew,
Chen Guangsheng,
Chen Jing Ming,
Ciais Philippe,
Davis Kenneth J.,
Desai Ankur,
Dietze Michael,
Dragoni Danilo,
Fischer Marc L.,
Flanagan Lawrence B.,
Grant Robert,
Gu Lianhong,
Hollinger David,
Izaurralde R. César,
Kucharik Chris,
Lafleur Peter,
Law Beverly E.,
Li Longhui,
Li Zhengpeng,
Liu Shuguang,
Lokupitiya Erandathie,
Luo Yiqi,
Ma Siyan,
Margolis Hank,
Matamala Roser,
McCaughey Harry,
Monson Russell K.,
Oechel Walter C.,
Peng Changhui,
Poulter Benjamin,
Price David T.,
Riciutto Dan M.,
Riley William,
Sahoo Alok Kumar,
Sprintsin Michael,
Sun Jianfeng,
Tian Hanqin,
Tonitto Christina,
Verbeeck Hans,
Verma Shashi B.
Publication year - 2010
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2009jg001229
Subject(s) - biome , environmental science , eddy covariance , biosphere model , temperate deciduous forest , biosphere , climatology , evergreen , atmospheric sciences , carbon cycle , temperate forest , deciduous , temperate rainforest , seasonality , terrestrial ecosystem , ecosystem model , vegetation (pathology) , ecosystem , ecology , medicine , pathology , biology , geology
Our current understanding of terrestrial carbon processes is represented in various models used to integrate and scale measurements of CO 2 exchange from remote sensing and other spatiotemporal data. Yet assessments are rarely conducted to determine how well models simulate carbon processes across vegetation types and environmental conditions. Using standardized data from the North American Carbon Program we compare observed and simulated monthly CO 2 exchange from 44 eddy covariance flux towers in North America and 22 terrestrial biosphere models. The analysis period spans ∼220 site‐years, 10 biomes, and includes two large‐scale drought events, providing a natural experiment to evaluate model skill as a function of drought and seasonality. We evaluate models' ability to simulate the seasonal cycle of CO 2 exchange using multiple model skill metrics and analyze links between model characteristics, site history, and model skill. Overall model performance was poor; the difference between observations and simulations was ∼10 times observational uncertainty, with forested ecosystems better predicted than nonforested. Model‐data agreement was highest in summer and in temperate evergreen forests. In contrast, model performance declined in spring and fall, especially in ecosystems with large deciduous components, and in dry periods during the growing season. Models used across multiple biomes and sites, the mean model ensemble, and a model using assimilated parameter values showed high consistency with observations. Models with the highest skill across all biomes all used prescribed canopy phenology, calculated NEE as the difference between GPP and ecosystem respiration, and did not use a daily time step.