Linking tropical cyclones in the ArabianSea and nitrous oxide distribution

Nitrous oxide being a biogenic gas that has both natural andanthropogenical sources, large uncertainties still persist in identifying its individual source strengths. In this article, focus is on the observed fluctuations in tropospheric concentration of N2O and its implications for the source strength of atmospheric N2O. It is well known that the anthropogenic sources are smoothly varying over the past years contributing to sustained tropospheric growth rates,whereas the natural sources can vary due to infrequent severe weather changes.

An attempt has been made to estimate the influence of cyclones in the Arabian Sea on the surface distribution of nitrous oxide (N2O) in the southern hemisphere. Reanalysed wind speeds during a cyclonic event are used to calculate N2O fluxes from the Arabian Sea. It is found that net emission of N2O from the Arabian Sea in a span of about 6 cyclonic days can contribute atleast 0.3% of its global oceanic sourcesand 2.5% from this particular oceanic region per annum. A simple parametric model is used for simulating the N2O abundance based on the observed cyclone frequency in the Arabian Sea. We have also employed a resampling echnique to show that the fluctuations in the N2O concentration in the southern hemisphere are closely linked with tropical cyclones in the Arabian Sea. Our time-lagged model leads us to propose a cause-and-effect relationship between the two.