Relationship Between Surface Ozone over South African Highveld and El Nino - Southern Oscillation
Open Access
Author:
Balashov, Nikolay Victor
Graduate Program:
Meteorology
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
November 07, 2012
Committee Members:
Anne Mee Thompson, Thesis Advisor/Co-Advisor
Keywords:
Ozone ENSO Southern Oscillation South Africa Highveld El Nino meteorology trend
Abstract:
Surface ozone variability due to El-Niño Southern Oscillation (ENSO) during 1990-2007 is examined at the Highveld – a heavily populated region in South Africa with numerous industrial facilities. The meteorological perturbations of the region are significantly affected by the variability in the sea surface temperature (SST) anomalies of the tropical eastern Pacific Ocean (ENSO). Surface ozone is sensitive to the meteorological conditions such as clouds because its production depends on the solar radiation to photolyse NO2. We use generalized linear regression model to establish any linear relationship that may exist between the Highveld ozone, measured at 5 ESKOM air quality monitoring stations, and ENSO. Our results find that 4 out of 5 stations are sensitive to the ENSO in the January-July period where El Niño with dry and warm anomalies acts to amplify the ozone, while La Niña with wet and cool anomalies act to reduce the ozone. The most consistent enhancement at these 4 stations is 4-6 ppbv in February-April period of 1998. The most consistent reduction is -3-5 ppbv in January-May of 1999 and 2000. In addition over the study period of 18 years three stations display negative ozone trend and two stations show no significant change in ozone.
