GNSS observations of deep convective time scales in the Amazon

In the tropics, understanding the shallow‐to‐deep transition and organization of convection on the mesoscale is made difficult due the paucity of long‐term high spatial/temporal resolution data. In this paper, data from the world's first long‐term equatorial Global Navigational Satellite System meteorological station in Manaus (Central Amazon) is used to create a new metric, a water vapor convergence time scale, to characterize the temporal evolution of deep convection over a tropical continental region. From 3.5 years of data, 320 convective events were analyzed using a compositing analysis. Results reveal two characteristic time scales of water vapor convergence; an 8 h time scale of weak convergence and 4 h timescale of intense water vapor convergence associated with the shallow‐to‐deep convection transition. The 4 h shallow‐to‐deep transition time scale is particularly robust, regardless of convective intensity, seasonality, or nocturnal versus daytime convection. This new result provides a useful metric for both high resolution and global climate models to replicate.