10 years of measurements from AIRS by using cloud state classification as derived from MODIS

Hyper spectral measurements from Infrared Sounders may be a good resource to detect atmospheric variations. However, it is difficult to classify the state of the clouds in the field of view of such instruments without additional information. Imagers on the same platform can help to classify these cloud states and cluster the radiative information accordingly. The Atmospheric InfraRed Sounder (AIRS) and the MODerate Resolution Imaging Spectroradiometer (MODIS) are both collocated on the same satellite platform Aqua. This enables us to use information from MODIS to determine type and variability of clouds within the field of view of AIRS. Both instruments are in orbit since 2003 and enable us to look on 10 years of combined observations.

We present an analysis of 10 years of AIRS and MODIS data with respect to classifications of simple cloud types and clear sky. We looked on variations of radiances (AIRS, Level 1), temperature and water vapor (AIRS, Level 2) and variation of cloud properties (MODIS Level 2) from 2003 to 2012. The first step was to look on global variations (between 65 N and 65 S) from year to year and identity regions with strong variability. This was done for mean values, but also for statistics of sampled data on a 10x10 degree grid around the globe. Regions with high variations are analyzed in more detail by looking on small-scale variations during the 10-year period. We look on correlation with weather indices and also trends with respect to long-term changes.