Table 1.

Global total CO₂ fluxes used in the 3 ACTM simulations (column 2–6), and estimated flux corrections (column 7–10) for different time windows given in column 1 (Units: PgC). Note here that these values are not strictly mass balanced as the XCO₂ differences are weighted by area of the 3 latitude bands, without knowing whether the mismatches at high latitudes in particular extend to the poles on either side.

Time window	A priori CO2 fluxes used for ACTM simulations					Patra et al.# (2005b)	CO2 flux corrections from OCO-2 – ACTM differences$
	FFC	CYC64	IAV84	IAV84 + GFAS	GFAS		CYC64	IAV84	IAV84 + GFAS
Oct 2014–Sep 2015	9.93	−2.86	−6.24	−4.27	1.97	2.67–2.73	−0.1–0.23	1.17–2.04	0.41–0.71
Oct 2015–Sep 2016	10.12	−2.86	−6.24	−5.57	0.67		−0.75–1.10	1.00–1.16	0.53–0.67
Jul 2015–Jun 2016 (main El Niño period)	10.08	−2.86	−6.24	−4.77	1.46		−0.18–0.29	1.50–2.18	0.77–1.09

^#Range estimated from two different fits, with (Flux anomaly = 0.3539 + 1.4935 × MEI amplitude change) or without (=−1.0756 + 2.4579 × MEI amplitude change) the La Niña years.

^$Range of estimation using two different approximations on area coverage (lower: latitudes covered by measurements; higher: global; refer to the main text for details).