Sensitivity of the Mipas on Envisat to the Detection of Polar Stratospheric Clouds and Their Composition

The MIPAS instrument has provided unprecedented information on the distribution and composition of polar stratospheric clouds. Both the spectral information in the measured data and its views of the poles are central to these advances. In this paper, the detection of polar stratospheric cloud particles is discussed and a threshold value of five for a defined MIPAS cloud index is shown to be suitable for PSC particles. Results are validated against observations from ground-based lidar and also the SAGE III and POAM III satellite instruments. A similar exercise is performed for a NAT spectral feature at 820 cm-1 where a threshold value for a defined NAT index of 0.1 is employed, allowing maps of PSC composition. These reveal very different NAT existence regimes between the two hemispheres in 2002/2003.