Influence of AAM-LOD on the lower stratospheric Ozone transport over Lagos--Nigeria


Abstract: An investigation of the relationship between Atmospheric Angular Momentum (AAM) via Length of Day (LOD) and the variability of Ozone (O_3) in the tropics with much emphasis on Lagos-Nigeria, using the global zonal wind data spanning 1997 to 2005 has been carried out. The mean O_3 concentration, O_3 temporal oscillation period, its average temporal amplitude of oscillation and its average maximum daily variation have been determined to be 273.6 \pm 0.04 DU, 5 days, 7.81 Du and 48.8 Du, respectively. The average monthly maximum and minimum O_3 concentrations were found to be 287.8 Du occurring between July and August; and 192.73 Du occurring between December and March respectively. These variations also follow the trend of the zonal wind speeds obtained for Nigeria between the periods under investigation. It was observed that the zonal wind speed has its peak in July and August with a decline from October to March. Consequently, the LOD and AAM vary in similar manner in the study area within the period under investigation. This observed behavior of the LOD and AAM and hence, the variation in the Ozone within the tropics, could be attributed to the effects of the extra-tropical suction pump (ETSP) action which causes the O_3 transport from the tropical stratosphere to the mid latitude region.

Keywords: AAM, LOD, zonal wind, Ozone, Dynamical process, tropics, stratosphere

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