concentration field and monthly variation of the CO
flux by NICAM-TM. (a) Mean CO2 concentration field at 250 hPa for June 2007, as simulated by NICAM-TM, and the locations of the CONTRAIL measurements for 2007 (white dots). (b) Monthly variation of the CO2 flux averaged for 2006 to 2008, estimated by the inversion analysis of Niwa et al. () (this figure is slightly modified from Figure 5d in Niwa et al. ). The blue and red lines are the CO2 fluxes (positive values indicate sources and negative values indicate sinks) estimated by only using surface data and by using both surface and CONTRAIL data, respectively, and the colored shades and error bars denote the range of the estimated flux uncertainty and standard deviation for 2006 to 2008, respectively.