The quasi-biennial oscillation (QBO), El Niño Southern Oscillation (ENSO), and upwelling in the tropical branch of the Brewer-Dobson circulation (BDC) impact tropical tropopause layer (TTL, 14–19 km) temperature (T) and relative humidity (RH), and thus it is likely that they also affect the TTL cloud distribution. Satellite data reveal extreme interannual variability in the zonal-mean TTL cloud occurrence frequency (CF) in the deep tropics (10°S–10°N). This zonal-mean interannual variability is related to the QBO and BDC, with a relatively minor role for ENSO. However, over the whole tropics (30°S–30°N), the dominant mode of variability in the longitudinally resolved CF field is an ENSO-related dipole pattern of positive and negative anomalies centered over the Pacific that mimics the RH/T fields. The ENSO effects largely cancel in the zonal mean, although El Niño is weakly associated with enhanced zonal-mean cloudiness in the uppermost TTL over the short satellite record.
If you can't find a tool you're looking for, please click the link at the top of the page to go "Back to old version". We'll be adding more features regularly and your feedback is important to us, so please let us know if you have comments or ideas for improvement.