Tropical upper-tropospheric ozone variability as observed by the Aura Microwave Limb Sounder

We present a survey of nearly five years of upper tropospheric ozone (O3) observations from the Microwave Limb Sounder (MLS) on NASA's Aura spacecraft. Seasonal and interannual variability in different tropical regions will be quantified and contrasted. Relationships with concurrent MLS observations of upper tropospheric carbon monoxide (CO, indicating polluted air) and cloud ice (a marker of convective activity) will be discussed. MLS O3 and CO observations in 'clear sky' and 'cloudy' conditions show significant differences in many regions and seasons, reflecting differences between freshly lofted and background upper tropospheric air. MLS observations are compared to selected calculations from established chemical transport models.