QBO and ENSO variability in temperature and ozone from SHADOZ, 1998–2005

Abstract

Temperature and ozone profiles from SHADOZ (1998–2005) radiosonde and ozonesonde profiles are analyzed. Data from four representative stations are used to investigate regional differences as well as QBO and ENSO influences on vertically fine structure. Principal components of the ozone profile time series at Kuala Lumpur (101°E, 3°N) are adopted as a stratospheric QBO index to study tropospheric temperature and ozone signatures associated with the QBO. A downward propagating QBO ozone signal extends to the mid-troposphere where the phase analysis of the temperature anomalies implies that the driving force is a zonal mean overturning circulation associated with thermal wind adjustment. The maximum tropospheric ozone anomalies associated with the QBO are ≈8 ppbv, about 10–20% that of typical tropical tropospheric ozone values, and differ in phase at the four sites. Temperature and ozone fields, linearly regressed against the QBO index, suggest that dynamical processes, including horizontal transport, play an important role in the observed tropospheric ozone anomalies. Temperature profiles, regressed against the Southern Oscillation Index (SOI), reveal anomalously cool, but also wavy lower stratospheric temperature anomalies over Kuala Lumpur and Nairobi (37°E, 1°S). Tropospheric ozone profiles associated with the SOI show a statistically significant signal that is consistent with anomalous vertical motions that are known to occur during ENSO, but also exhibit fluctuations at a 40–50 day time scale.