Temporal Variation of Stratospheric Ozone Observed at the Southern Tip of South America during Austral Spring

HIROFUMI OHYAMA; AKIRA MIZUNO; TOMOO NAGAHAMA; JACOBO SALVADOR, ELIAN WOLFRAM, FÉLIX ZAMORANO

Kobe

Conferencia; The 13 th Atmospheric Sciences and Application to Air Quality (ASAAQ13); 2015

Meteorological Society of Japan, National Institute for Environmental Studies, and RIKEN Advanced Institute for Computational Science et al.,

During austral spring, polar vortex often passes over the Patagonia area (south parts of Argentina and Chili). In addition, during austral late spring when the polar vortex breaks down, airmass with low ozone occasionally stays around the Patagonia area (de Laat et al., 2010), which results in an exposure of harmful ultraviolet (UV) radiation for a relatively long time. In order to monitor variations of the UV radiation and ozone (O3) amounts with a time scale of a few hours, we have performed synthetic observations at the Patagonia area with an UV radiometer, a millimeter-wave spectroscopic radiometer (MWR), a differential absorption lidar (DIAL), and an ozonesonde. The MWR, which was installed at Río Gallegos (51.6S, 69.3W), Argentina, has recorded an emission spectrum around 110 GHz owing to rotational transition of the atmospheric O3 molecules. The O3 profiles that have sensitivity between 20 and 70 km are retrieved from the spectra with an integration time of 1 h by the optimal estimation scheme (Ohyama et al., 2015). In October and November 2014, we performed coincident observations with the three instruments (MWR, DIAL, and sonde), and compared the O3 profiles derived from the respective instruments. We found that the O3 profiles are in agreement within 10-20% for one another. Figure 1a shows time series of O3 mixing ratio at 30 km altitude observed with the MWR during the intercomparison campaign. Decreases of O3 mixing ratio can be seen during the periods indicated by arrows. The temporal variations of O3 mixing ratios are then compared with potential vorticity and equivalent latitude (EqL), which are calculated from MERRA reanalysis data. Figure 1b shows time series of equivalent latitude at Río Gallegos and at edge of polar vortex on a potential temperature of 800 K. The temporal variation of O3 is quite similar to that of the EqL. We will discuss in detail the causes of the O3 variations at each altitude.