Local identification of equatorial mixed Rossby–gravity waves

Abstract We propose a local identification method for mixed Rossby–gravity (MRG) waves, which include both eastward mixed Rossby–gravity (EMRG) waves, also known as eastward inertia–gravity (EIG1) waves, and westward mixed Rossby–gravity (WMRG) waves. The method identifies MRG waves at specific longitudes using only a pair of EMRG and WMRG meridional structures. A criterion is proposed to estimate WMRG wave dominance within the identified MRG wave field. Propagation of WMRG waves can then be studied at specific longitudes. The method has the main advantages of (1) identifying MRG waves in data from a single longitude and pressure level without need for global data and (2) requiring very low computational cost to apply. Finally, it is found that MRG waves alone explain more than 90% of the variance of the latitudinal average of the equatorial meridional wind at 850 hPa and more than 95% at 200 hPa.