The meteorological environment of the tropospheric ozone maximum over the tropical South Atlantic

• Main Authors: T. N. Krishnamurti, H. E. Fuelberg, M. C. Sinha, D. Oosterhof, N. K. Bensman, V. B. Kumar
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1993
• Subjects: South Atlantic Ocean
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.666.1959; http://fuelberg.met.fsu.edu/publications/krishnamurti-fuelberg-1993.pdf

Atmospheric flow patterns are examined over the South Atlantic Ocean where a maximum of tropospheric ozone has been observed just west of southern Africa. We investigate the flow climatology during October and perform a case study for 6 days during October 1989. Analyses from the European Center for Medium-Range Weather Forecasting are employed, and a high-resolution global spectral model is used to prepare forecasts during the period. Horizontal and vertical motions are examined and used to prepare three-dimensional backward trajectories from the region of greatest ozone. An initially zonally symmetric distribution of ozone is treated as a passive tracer and advected by three-dimensional flows forecast by the global model. Results from the passive tracer simulation indicate that three-dimensional advection alone can produce a maximum of tropospheric ozone in the observed location. In addition, the trajectories suggest that by-products of biomass burning could be transported to the area of maximum ozone. Low-level flow from commonly observed regions of burning in Africa streams westward to the area of interest. Over Brazil, if the burning by-products are carried into the upper troposphere by convective process, they then could be transported eastward to the ozone feature in approximately 5 days. There is considerable subsidence over the tropical southern Atlantic, such that stratospheric influences also are a factor in producing the ozone maximum. Both planetary-scale and transient synoptic-scale circulation features play major roles in the various transport processes that influence the region. In summary, the observed tropospheric ozone maximum appears to be caused by a complex set of horizontal and vertical advections, transport from regions of biomass burning, and stratospheric influences. 1.