UPWELLING INTO THE LOWER STRATOSPHERE & TROPICAL WAVE BREAKING: EVIDENCE FROM CHEMICAL TRACERS

Abstract

We use 2005 - 2010 measurements from the Microwave Limb Sounder (MLS) instrument to calculate the deseasonalized anomalies of tropical mean water vapor (H2O), carbon monoxide (CO), and nitrous oxide (N2O) on the 68 hPa surface. We then calculate the spatial maps of the coherence between the tropical mean tracer measurements and reanalysis temperature on the 100 hPa surface, in both the subseasonal and multiyear time windows. In the multiyear time window, the spatial pattern of the coherence, and the time lags, indicate that fluctuations in 100 hPa temperature affect 68 hPa H2O through changes in dehydration efficiency. In the subseasonal time window, the coherence between 100 hPa temperature and 68 hPa H2O is mediated through changes in upwelling driven by the dissipation of tropical Rossby waves. On subseasonal timescales, the 68 hPa anomalies in tropical mean CO are strongly coherent with the Madden Julian Oscillation (MJO).