Distributions and Characteristics of Overshooting Tops

Overshooting tops (OTs) form when strong updrafts overshoot their level of neutral buoyancy and cross the tropopause. Convective storms with OTs are often associated with severe weather and provide a pathway for stratosphere-troposphere exchange. Many regions around the globe are known hotspots for deep convection, but the global spatial and temporal distributions of OTs are not well understood. Previous attempts have been made to create climatologies using older geostationary satellite data. However, the temporal resolution of such observations (30 minutes) far exceeds the established lifetime of typical OTs (<15 minutes), thus severely under-sampling the frequency of these features. The goal of this study is to create a high-temporal resolution, near-global satellite-based OT database. This database is used to develop an OT climatology and derive associated OT characteristics, such as minimum bright temperature magnitudes, OT area, and the number of OTs within each associated cloud anvil region. As such, this work aims not only to characterize when and where OTs occur, but also how OT characteristics vary as a function of region, environment, and the diurnal cycle.

To address this goal, overshooting convective features identified across 7 years of 10-15 minute geostationary satellite data (GOES-R series, Himawari 8/9, and Meteosat 8/9) are tracked in space and time with the Tracking and Object-Based Analysis of Clouds (tobac) algorithm. By leveraging tobac’s segmentation tool and a modified version of the infrared window (IRW)-texture method, climatologies of OT characteristics are built for six key regions: North America, South America, Europe, Africa, the Maritime Continent, and Australia. This database contains novel information of overshooting tops and their associated cloud anvils.

In this presentation, the regional climatologies will be presented; each of which reveals important information about the spatial, diurnal, and seasonal variability of overshooting convection.