Quantifying Surface Energy Fluxes in the Vicinity of Inland-Tracking Tropical Cyclones

Abstract

Tropical cyclones (TCs) typically weaken or transition to extratropical cyclones after making landfall. However, there are cases of TCs maintaining warm-core structures and intensifying inland unexpectedly, referred to as TC maintenance or intensification events (TCMIs). It has been proposed that wet soils create an atmosphere conducive to TC maintenance by enhancing surface latent heat flux (LHF). In this study, “HYDRUS-1D” is used to simulate the surface energy balance in intensification regions leading up to four different TCMIs. Specifically, the 2-week magnitudes and trends of soil temperature, sensible heat flux (SHF), and LHF are analyzed and compared across regions. While TCMIs are most common over northern Australia, theoretically linked to large fluxes from hot sands, the results revealed that SHF and LHF are equally large over the south-central United States. Modern-Era Retrospective Analysis for Research and Applications (MERRA) 3-hourly LHF data were obtained for the same HYDRUS study regions as well as nearby ocean regions along the TC path 3 days prior (prestorm) to the TC appearance. Results indicate that the simulated prestorm mean LHF is similar in magnitude to that obtained from MERRA, with slightly lower values overall. The modeled 3-day mean fluxes over land are less than those found over the ocean; however, the maximum LHF over the 3-day period is greater over land (HYDRUS) than over the ocean (MERRA) for three of four cases. It is concluded that LHF inland can achieve similar magnitudes to that over the ocean during the daytime and should be pursued as a potential energy source for inland TCs.

Evacuee Perception of Geophysical Hazards for Hurricane Irma

“…The small samples collected for Hurricanes Harvey and Isaac also showed positive mean PMWS 2 APG, albeit a slightly smaller range than Irma. The vast majority of storms weaken soon after landfall, unless latent heat energy is available over land (Andersen et al 2013). These positive PMWS 2 APG results suggest that misperception of wind speeds after landfall is possibly widespread and common for hurricane evacuees, but such a conclusion could only be reached through a larger sample size from several landfalling hurricanes.…”

The Surface Energy Balance at Panda 1 Station, Princess Elizabeth Land: A Typical Katabatic Wind Region in East Antarctica

“…The surface mass and energy balance of the Antarctic ice sheet is also sensitive to small changes in meteorology and topography (Huybrechts, 1990;Marsiat & Bamber, 1997;Gallée et al, 2001;Sun et al, 2018). Extratropical cyclones have a great impact on the Antarctic SEB, particularly when they are land-tracking (Andersen et al, 2013;Rinke et al, 2017;Woods et al, 2013;Xie et al, 2002). Polar cyclones in this sector of East Antarctica develop mostly in the southern Indian Ocean to the northwest of Prydz Bay, with more cyclones in winter than in summer (Simmonds & Keay, 2000;Qin et al, 2017).…”

The Hurricane Harvey (2017) Texas Rainstorm: Synoptic Analysis and Sensitivity to Soil Moisture

“…This result suggests that perhaps Harvey's environment after landfall was still influenced by the nearby ocean which lessened the importance of the underlying soil moisture condition. In the context of the brown ocean effect's influence on tropical cyclone maintenance inland, Andersen et al (2013) defined inland tropical cyclones as systems at least 350 km from the nearest coastline. Harvey remained within 350 km of the coastline, with the eastern part of its circulation remaining over the Gulf of Mexico.…”

“…This result is consistent with Zhang et al (2017) who showed that forecasts of intensification using the Hurricane Weather Research and Forecasting (HWRF) Model are improved when using a planetary boundary layer (PBL) parameterization that allows for a shallower PBL with stronger lowlevel inflow and convergence. Recent efforts to study the intensity evolution of tropical systems after landfall has led to the development of the ''brown ocean'' concept, where rainfall produces anomalously moist soil conditions and enhanced surface latent heat fluxes (e.g., Andersen and Shepherd 2017).…”