HR: 09:40h
AN: AE21A-09    [Abstracts]
TI: Satellite Detection of Lightning NO$_2$ and Implications for Lightning Parameterizations
AU: * Boersma, F
EM: boersma@knmi.nl
AU: Eskes, H
EM: eskes@knmi.nl
AU: Meijer, E
EM: meijere@knmi.nl
AB: Nitrogen oxides (NO$_x$ = NO + NO$_2$) from lightning flashes contribute to the formation of ozone in the upper troposphere, and have a strong effect on the oxidizing capacity of the atmosphere. However, recent estimates of annual global lightning NO$_x$ emissions range by one order of magnitude, and this makes it difficult for chemistry-transport models to properly quantify the impact of lightning NO$_x$ on ozone and OH. The uncertainties mostly result from modelling NO$_x$ from lightning in a "bottom-up" way, requiring important assumptions on certain lightning characteristics with limited observational constraints. Here we provide evidence that retrievals of tropospheric NO$_2$ from the Global Ozone Monitoring Experiment (GOME) contain spatially and temporally resolved information on tropical tropospheric distributions of lightning NO$_x$. From comparing modeled lightning, and observed total NO$_2$, we find that the production of lightning NO$_x$ over tropical oceans is significantly overestimated in parameterizations relating convective rainfall, or cloud top heights, to lightning flash frequencies. From a simple, first-order correction for the regionally different oceanic overestimations, it follows that global lightning NO$_x$ emissions amount to ~4.1 Tg [N] for 1997.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0322 Constituent sources and sinks
DE: 0368 Troposphere--constituent transport and chemistry
DE: 0933 Remote sensing
SC: Atmospheric and Space Electricity [AE]
MN: 2004 AGU Fall Meeting