It has been suggested that the tropical tropopause layer (TTL) may be affected by mixing from shear-flow instability in connection with Kelvin waves. It is shown that the revised Louis-scheme (used in operational analyses and ERA-40 and ERA-Interim of ECMWF) strongly responds to Kelvin wave perturbations, and average mixing is maximized where Kelvin wave amplitudes are largest (Indian ocean/Maritime continent). Conversely, the Monin-Obukhov scheme predicts fewer, but more intense mixing events that maximize further East. For the TTL, the mixing predicted by the two schemes is similar and small, but locally the models predict shear-flow mixing sufficient to yield net diabatic descent over the aforementioned regions. The data analyzed here remains inconclusive about which scheme captures reality better, rendering the role of Kelvin waves for shear-flow instability uncertain. The mixing schemes' sensitivity to Kelvin waves has implications for the dissipation of Kelvin waves in models and analyzed meteorological data.
All Science Journal Classification (ASJC) codes
- General Earth and Planetary Sciences