Effects of the 2006 El Niño on tropospheric ozone and carbon monoxide: implications for dynamics and biomass burning
We have studied the effects of the 2006 El Ni no on tropospheric O3 and CO at tropical and sub-tropical latitudes measured from the OMI and MLS instruments on the Aura satellite. The 2006 El Ni no-induced drought caused forest fires (largely set to clear land) to burn out of control dur- ing October and November in the Indonesian region. The effects of these fires are clearly seen in the enhancement of CO concentration measured from the MLS instrument. We have used a global model of atmospheric chemistry and transport (GMI CTM) to quantify the relative importance of biomass burning and large scale transport in producing ob- served changes in tropospheric O3 and CO. The model re- sults show that during October and November biomass burn- ing and meteorological changes contributed almost equally to the observed increase in tropospheric O3 in the Indone- sian region. The biomass component was 46DU but it was limited to the Indonesian region where the fires weremost in- tense. The dynamical component was 48DU but it covered a much larger area in the Indian Ocean extending from South East Asia in the north to western Australia in the south. By December 2006, the effect of biomass burning was reduced to zero and the observed changes in tropospheric O3 were mostly due to dynamical effects. The model results show an increase of 23% in the global burden of tropospheric ozone. In comparison, the global burden ofCOincreased by 812%.