Comparison of ozone profiles from DIAL, MLS, and chemical transport model simulations over Río Gallegos, Argentina, during the spring Antarctic vortex breakup, 2009

Abstract

Abstract. This study evaluates the agreement between ozone profiles derived from the ground-based differential absorption lidar (DIAL), satellite-borne Aura Microwave Limb Sounder (MLS), and 3-D chemical transport model (CTM) simulations such as the Model for Interdisciplinary Research on Climate (MIROC-CTM) over the Atmospheric Observatory of Southern Patagonia (Observatorio Atmosférico de la Patagonia Austral, OAPA; 51.6 • S, 69.3 • W) in Río Gallegos, Argentina, from September to November 2009. In this austral spring, measurements were performed in the vicinity of the polar vortex and inside it on some occasions; they revealed the variability in the potential vorticity (PV) of measured air masses. Comparisons between DIAL and MLS were performed between 6 and 100 hPa with 500 km and 24 h coincidence criteria. The results show a good agreement between DIAL and MLS with mean differences of ±0.1 ppmv (MLS − DIAL, n = 180) between 6 and 56 hPa. MIROC-CTM also agrees with DIAL, with mean differences of ±0.3 ppmv (MIROC-CTM − DIAL, n = 23) between 10 and 56 hPa. Both comparisons provide mean differences of 0.5 ppmv (MLS) to 0.8-0.9 ppmv (MIROC-CTM) at the 83-100 hPa levels. DIAL tends to underestimate ozone values at this lower altitude region. Between 6 and 8 hPa, the MIROC-CTM ozone value is 0.4-0.6 ppmv (5-8 %) smaller than those from DIAL. Applying the scaled PV (sPV) criterion for matching pairs in the DIAL-MLS comparison, the variability in the difference decreases 21-47 % between 10 and 56 hPa. However, the mean differences are small for all pressure levels, except 6 hPa. Because ground measurement sites in the Southern Hemisphere (SH) are very sparse at mid-to high latitudes, i.e., 35-60 • S, the OAPA site is important for evaluating the bias and long-term stability of satellite instruments. The good performance of this DIAL system will be useful for such purposes in the future.

Analysis of the Ozone Reduction Event Over the Southern Tip of South America in November 2009

“…At Rio Gallegos (51.5°S, 69.3°W) in the southern tip of South America, lidar measurements of the ozone profile were taken in spring 2009 (Wolfram et al, ), and a comparison among the lidar observations, the satellite observations by the Microwave Limb Sounder, and a nudged chemistry‐climate model simulation from September to November was performed (Sugita et al, ). These observations and the model simulation demonstrated changes in the vertical profile of the ozone during the low‐ozone event in November 2009.…”

Reconstructing the ozone concentration profile using machine learning methods

“…Laser methods of atmospheric sensing make it possible to determine such physical characteristics of the atmosphere as pressure, temperature and to measure concentrations of gas impurities in a wide range of altitudes (0-100 km) [1][2][3][4]. At present, the main tools of such sensing are laser locators (lidars).…”

Analysis of a southern sub-polar short-term ozone variation event using a millimetre-wave radiometer

“…Recent partial column ozone analysis from satellite ozone composites indicates a decadal increase in the upper stratosphere that is statistically significant (WMO, 2014;Harris et al, 2015;Steinbrecht et al, 2017;Ball et al, 2017Ball et al, , 2018Frith et al, 2017), attributed in part to the decline of the ODS. On the other hand, an unexpected decrease in the partial column ozone in the lower stratosphere has been suggested, although with a low level of confidence (Nair et al, 2015;Vigouroux et al, 2015;Ball et al, 2018). A globalscale study (between 60 • N and 60 • S) confirmed a significant decrease in partial column ozone in the lower stratosphere at tropical latitudes with a high level of significance, accounting for a continued and uninterrupted decline of the order of ∼ 2.2 DU between 1998 and 2016 (Ball et al, 2018).…”