“…Bayesian synthesis (Enting, 2002), four dimensional variational data assimilation methods (4DVar; 10 Chevallier et al, 2009a10 Chevallier et al, , 2009b10 Chevallier et al, , 2010Kou et al, 2017), and Ensemble Kalman Filter (EnKF; Peters et al, 2005Peters et al, , 2007Peters et al, , 2010Feng et al, 2009Feng et al, , 2016Kang et al, 2011Kang et al, , 2012Peylin et al, 2013;Kim et al, 2014aKim et al, , 2014bKim et al, , 2017Kim et al, , 2018aKim et al, , 2018b have been implemented and utilized to conduct inverse modeling. By comparing 13 inverse modeling systems, Peylin et al (2013) showed that simulation results were similar to each other for regions with many observations, but dissimilar for regions with sparse observation 15 coverage (e.g.…”