Ozone instantaneous longwave radiative effect from IASI and TES observations

Ozone is one of the most important greenhouse gases in terms of radiative forcing as a result of increases in its precursor emissions since pre-industrial times. Until recently, the ozone radiative forcing calculations were entirely model based, exhibiting high uncertainties and a large spread in model values, as shown in the IPCC AR5. Satellite sounders operating in the infrared now offer the possibility to infer directly the longwave radiative effect (LWRE) of ozone in the 9.6 μm band, with respect to its vertical distribution, allowing to better constrain model estimates of the ozone radiative forcing and its future predictions. In this presentation we calculate the ozone LWRE by exploiting the measurements of IASI/MetOp-A. We briefly describe a new method for calculating the ozone LWRE and the flux sensitivity with respect to the ozone profile, known as instantaneous radiative kernel (IRK), and we demonstrate that it is more accurate than previous existing methods by up to 30%. We also show a first comparison with similar quantities derived from measurements of TES/Aura and report a very good agreement overall. Finally, we present the application of such calculation, made at unprecedented resolution and sampling with IASI, in climate models and the ability of assessing the biases of the latter in terms of radiative effect.