SEPTEMBER 2001: El Nino effect on tropospheric ozone

Shown is the effect of El Niño on tropical tropospheric ozone columns calculated from tropospheric ozone columns for October 1997 minus those for October 1996. The top panel shows the effect determined from the Total Ozone Mapping Spectrometer (TOMS) instrument using the convective cloud differential method. The bottom panel shows the effect calculated with the GEOS-CHEM model. The high degree of consistency between the two (and with ozonesondes as further described in [Chandra et al., 2001]) suggests that the GEOS-CHEM model provides a useful tool to separate the influence of dynamics and biomass burning on tropical tropospheric ozone. We find that about half of the El Niño induced ozone enhancement over Oceania arises from dynamics and half from biomass burning. For more details, please see the recently accepted paper [Chandra et al., 2001].