Application of the Turbulent Vortex Dynamo Theory for Early Diagnostics of the Tropical Cyclone Genesis

Abstract

The climate change is becoming more and more obvious, which leads to an increase in the number of intense atmospheric vortices (tropical and quasi-tropical cyclones, polar hurricanes, tornadoes) and an expansion of the geographical and seasonal limits of their occurrence. A recent example was the quasi-tropical cyclone in the Black Sea on August 11–16, 2021. Under these conditions, the accurate diagnosis of cyclogenesis is extremely important and, based on it, the forecast of further evolution and the trajectory of the forming vortex. The main source of energy for tropical, quasi-tropical and polar hurricanes is thermal convection caused by significant temperature differences between the atmospheric layer and the underlying water surface. This allows us to propose a unified approach for the diagnosis of cyclogenesis in all three cases.For the first time, an original approach is proposed for determining the exact time of the onset of tropical cyclogenesis. This approach includes a combined analysis of satellite images of cloudiness and the corresponding data of cloud-resolving numerical modeling for the region of developing vortex disturbance. The theoretical basis is the fundamental hypothesis of a turbulent vortex dynamo. The theory provides quantitative criteria that determine the excitation of large-scale vortex instability in the atmosphere. Atmospheric numerical modeling makes it possible to accurately determine the moment of time at which the necessary conditions for the onset of instability are realized. This moment is interpreted as the beginning of cyclogenesis. The specific configurations of vortical cloud convection found in the work, which correspond to the initial stage of cyclogenesis, can be used in operational meteorological diagnostics when analyzing satellite images of cloudiness. The approach is illustrated by the example of diagnostics of tropical cyclogenesis.