Techniques for the Identification and Modification of Simulated Tropical Waves

The accurate representation of atmospheric waves in the tropics is a key operational challenge, in part because these systems have significant impacts. Easterly waves (EWs) provide essential rainfall, trigger localized flooding events, and are often the seeds for tropical cyclone (TC) formation. Meanwhile, convectively coupled equatorial waves (CCEWs) modify rainfall around the world and are also associated with extreme weather events. In this talk, we discuss several tools for the identification and quantification of these features in reanalysis and numerical model simulations.

First, we review methods for tracking and quantifying EW characteristics. A few of these EW trackers, such as the Lawton et al. (2022) QTrack python module, have publicly available code. The strengths and weaknesses of various EW trackers are compared, and we present several examples of their use. Focus is placed on the applications of these methods to real-time forecasting.

Next, we discuss the identification and modification of CCEWs in numerical models. We present several tools for the tracking and quantification of CCEWs in numerical simulations, especially their convective coupling. This includes a modification method recently published by Lawton et al. (2024). Focus is placed on identifying the predictability and forecast skill of individually tracked CCEWs.

Ultimately, it is demonstrated that these tropical wave diagnostic tools can provide essential insights into numerical model performance. Identifying areas in which these models perform poorly is important for guiding improvements to these systems, which could eventually lead to improvements in weather forecasts.