The impact of Mixed Rossby-Gravity waves on the interannual variation of tropical cyclones over western North Pacific

Abstract:

The wave transformation of mixed-Rossy gravity (MRG) waves into Tropical Depression (TD) type has been suggested to be related to Tropical cyclone (TC) genesis in the western Pacific (Dickinson and Monlinari 2002, Zhou and Wang 2007). It was also discussed that the transformation is made possible by the zonal confluence where the monsoon westerlies meet the trade wind easterlies (Kuo et al 2001 and Aiyyer and Molinari 2001).

In this study, a new algorithm is developed to track MRG waves in both space and time in reanalysis data, based on a method proposed by Yang et al (2003), so that the recorded MRG waves can be used to study their relationships with TC genesis. Our results of the inter-annual variations of MRG waves show that TC genesis is sensitive to MRG waves activity in a certain region. Results also show that occurrences of MRG waves have different degrees of impact on TC genesis in different months.