Evaluation of the Capability of ExoMars-TGO NOMAD Infrared Nadir Channel for Water Ice Clouds Detection on Mars

As part of the payload 2016 ExoMars Trace Gas Orbiter (TGO) mission, Nadir and Occultation for MArs Discovery (NOMAD) suite instrument has been observing Martian atmosphere since March 2018. NOMAD is mainly dedicated to study trace atmospheric species taking advantage a high-spectral resolution. We demonstrate that when in nadir mode, i.e., line-of-sight points centre Mars, it can be also exploited detect ice. In this we present method based on investigation observations infrared channel, acquired during Mars Years 34 35 (March 2018 February 2021). take strong water ice absorption band at 2.7 µm by selecting diffraction orders 167, 168, 169. derive Frost Clouds Index (FCI), which good proxy mapping, obtain latitudinal-seasonal maps clouds. FCI sensitive Polar Hood Nevertheless, detections Aphelion Cloud Belt (ACB) are limited. This consistent with previous showing different physical properties between two main structures making ACB less detectable infrared. hence channel sensitivity limit detection these