Variability of Stratospheric Reactive Nitrogen and Ozone Related to the QBO

Abstract

The stratospheric quasi‐biennial oscillation (QBO) dominates interannual variability of dynamical variables and trace constituents in the tropical stratosphere and provides a natural experiment to test circulation‐chemistry interactions. This work quantifies the relationships among ozone (O3), reactive nitrogen (NOy), and source gas N2O, and their links to the QBO, based on satellite constituent measurements and meteorological data spanning 2005–2014 (over four QBO cycles). Data include O3, HNO3, and N2O from the Aura Microwave Limb Sounder and an NOx proxy derived from Optical Spectrograph and Infrared Imager System NO2 measurements combined with a photochemical box model (= NOx*). Results are compared to simulations from the Whole Atmosphere Community Climate Model, version 4 incorporating a QBO circulation nudged to assimilated winds. Cross correlations and composites with respect to the QBO phase show coherent 180° out‐of‐phase relationships between NOy and N2O throughout the stratosphere, with the NOx/HNO3 ratio increasing with altitude. The anomalies in NOy species propagate coherently downward with the QBO. Ozone is anticorrelated with reactive nitrogen in the middle stratosphere above ~28 km due to NOx control of ozone catalytic loss cycles. Quantitative comparisons of nitrogen partitioning and O3 sensitivity to NOx show good overall agreement between satellite observations and model results (suggesting closure of the NOy budget), although the model results show larger (up to ~20%) N2O, NOx, and O3 variations near ~35 km compared to observations. These analyses serve to assess the consistency of diverse satellite‐based data sets and also to evaluate nitrogen partitioning and NOx‐dependent ozone chemistry in the global model.

Trends and Variability in Stratospheric NOx Derived From Merged SAGE II and OSIRIS Satellite Observations

“…The top panel of Figure shows that the QBO is clear in both data sets near 30 km in the tropics, with consistent phase and amplitude between the model and observations. This is consistent with previous results from Park et al (). Both WACCM and SAGE II‐OSIRIS also show similar variations outside of the tropics, as can be seen in the bottom two panels of Figure .…”

“…We applied a standard linear regression model to the merged data in order to quantify NO x variability tied to the QBO, linear trends, and volcanic aerosol. The QBO coefficients (not shown) have similar structure and values to those derived by Park et al () using OSIRIS and WACCM NO x from 2005 to 2014, with good agreement between observational and model results. The novel information here regards the long‐term trends and volcanic aerosol fits in the regressions.…”

“…The source of the very high OSIRIS anomaly from 2002 to 2005 is the early local solar time of the measurements relative to the rest of the data (see Figure ). Above 25 km the magnitude of the WACCM anomaly is greater than the OSIRIS anomaly, which was also observed by Park et al (). The missing SAGE II data at the lower altitudes from 1991 to 1993 are due to an inability to retrieve NO 2 following large aerosol injections from volcanic eruptions.…”

“…The variability in NO x from the Optical Spectrograph and InfraRed Imager System (OSIRIS, Llewellyn et al, 2004) was first studied by Park et al (2017). They used OSIRIS NO 2 from 2005 to 2014 in conjunction with N 2 O, HNO 3 , and O 3 from the microwave limb sounder (Aura/MLS, Waters et al, 2006) to examine variations in NO y associated with the quasi-biennial oscillation (QBO).…”

Partitioning of Ozone Loss Pathways in the Ozone Quasi-biennial Oscillation Simulated by a Chemistry-Climate Model

“…Detailed vertical and temporal structures of the QBO in O3 and NO2 were revealed through Stratospheric Aerosol and Gas Experiment (SAGE) II data by Zawodny and McCormick (1991), Hasebe (1994), and Chipperfield et al (1994), and through Global Ozone Monitoring by Occultation of Stars (GOMOS) data by Hauchecorne et al (2010) and Liu et al (2011). Also Park et al (2017) showed the detailed structures of the QBO in O3, NOx, N2O, and HNO3 by analyzing Optical Spectrograph and Infrared Imager System (OSIRIS) data. These studies demonstrated that, different from zonal-wind, temperature, and NO2, the ozone QBO has a distinctly sharp phase change (transition) at around 28km, where the transition occurs between dynamical control below and photochemical control above.…”