Antarctic polar stratospheric cloud composition as observed by ACE, CALIPSO and MIPAS

The composition of polar stratospheric clouds (PSCs) in the Antarctic is measured by infrared absorption spectroscopy by the Atmospheric Chemistry Experiment (ACE) satellite and compared to lidar (CALIPSO) and emission spectroscopy (MIPAS) results. ACE observations are compared first to CALIPSO for the period 2006-2020, then to MIPAS for the period 2005-2011, and then a set of triple coincidences is studied. In both CALIPSO-ACE and MIPAS-ACE comparisons, nitric acid trihydrate (NAT) detections are in excellent agreement (∼80% of coincident compositions is found). Supercooled ternary solution (STS) detections are in good agreement for CALIPSO-ACE (∼60%) but in poor agreement for MIPAS-ACE (39%). This contrasts with ice detections, in poor agreement for CALIPSO-ACE (∼30%) and in better agreement for MIPAS-ACE (45%). Triple coincidences show that ACE STS detections are more reliable than MIPAS STS detections. ACE observations compared to homogeneous CALIPSO PSCs show that for 11 observations, CALIPSO is observing supercooled nitric acid (SNA) clouds rather than STS clouds.