Vertical Coupling of Gusts in the Lower Boundary Layer During Super Typhoons and Squall Lines

Identifying the coupling relationships between gusts at different altitudes of weather systems over land is essential to recognize the inherent energy transfer patterns of different types of windy weather systems and design civil structures and infrastructures. Using the time-lagged convergent cross-mapping (LCCM) and data obtained from the 356-m-high Shenzhen Meteorological Gradient Tower, we present an observational study of the gusts and momentum flux of two super typhoons (STs) and two squall lines (SLs). Compared to STs, the gusts in SLs are characterized by high amplitude bursts and first occur near the surface. Bivariate toy models and observational data showed that LCCM reliably identifies coupling relationships in the nonlinear system. Subsequently, we systematically demonstrated that LCCM can identify long-distance interactions of multilevel gusts in different types of gale weather systems. Finally, the downward transportation of energy in ST was verified from the perspective of wind structure and turbulent vertical flux. The upper-level STs gusts varied ahead of the lower-level gusts, whereas the SLs showed the opposite result, which is consistent with the coupling relationship obtained by the LCCM method. The results of the study are expected to enhance the understanding of the characteristics of multilevel energy transfer of TC and SL boundary layers over land, provide useful information for validating numerical weather prediction models of damaging weather systems, and facilitate gale hazard prevention in coastal regions.