Advantages of the synergy between limb and nadir observations: 2D data fusion of CAIRT, IASI-NG and Sentinel 5 simulated data

The Changing-Atmosphere Infra-Red Tomography Explorer (CAIRT) is one of the four candidates for ESA's Earth Explorer 11. By exploiting its imaging capabilities, CAIRT can sound the atmosphere simultaneously from the middle troposphere to the lower thermosphere at high spectral resolution and with unprecedented horizontal and vertical resolution. Flying in loose formation with MetOp-SG mission allows to combine spatially resolved limb observations with horizontally resolved nadir measurements of IASI-NG and Sentinel-5 nadir spectrometers to extend limb observations down to the surface. We have evaluated further possible advantages coming from the exploitation of the synergy between limb and nadir imaging observations for Ozone in 2D, i.e. with the analysis performed both in the vertical direction and in the along track direction. The synergistic products are characterised on one hand by a better quality in the troposphere than the one of nadir only measurements, thanks to the limb measurement knowledge on the vertically resolved stratosphere, on the other hand also by a better quality in the Upper Troposphere - Lower Stratosphere than the one of limb observations only, thanks to the nadir measurements knowledge on the horizontal variability of the atmosphere in the troposphere. We will show results obtained with the rigorous approach of 2D complete data fusion for realistic simulations of CAIRT, IASI-NG and Sentinel 5 observations.