Stratified coastal ocean interactions with tropical cyclones

Abstract

Hurricane-intensity forecast improvements currently lag the progress achieved for hurricane tracks. Integrated ocean observations and simulations during hurricane Irene (2011) reveal that the wind-forced two-layer circulation of the stratified coastal ocean, and resultant shear-induced mixing, led to significant and rapid ahead-of-eye-centre cooling (at least 6 °C and up to 11 °C) over a wide swath of the continental shelf. Atmospheric simulations establish this cooling as the missing contribution required to reproduce Irene's accelerated intensity reduction. Historical buoys from 1985 to 2015 show that ahead-of-eye-centre cooling occurred beneath all 11 tropical cyclones that traversed the Mid-Atlantic Bight continental shelf during stratified summer conditions. A Yellow Sea buoy similarly revealed significant and rapid ahead-of-eye-centre cooling during Typhoon Muifa (2011). These findings establish that including realistic coastal baroclinic processes in forecasts of storm intensity and impacts will be increasingly critical to mid-latitude population centres as sea levels rise and tropical cyclone maximum intensities migrate poleward.

Rapid shelf‐wide cooling response of a stratified coastal ocean to hurricanes

“…Techniques empirically derived for the MAB to remove bright cloud covered pixels and retain darker ocean pixels were used to decloud AVHRR data but preserve the rapid TC cooling signal, following Glenn et al . [].…”

“…It is also critical to understand the spatial—cross‐shelf and along‐shelf, shallow and deep water—variability of the cooling processes, for a wider range of storms including Irene. Previous studies focused on these processes at the underwater glider location and not elsewhere on the MAB continental shelf [i.e., Glenn et al ., ]. These research gaps will guide this paper's work.…”

“…The number of studies in the literature investigating shallow, coastal ocean TC responses, indeed, pales in comparison to the number examining deep, open ocean TC responses [ Seroka et al ., ]. Further, the differences between the deep, open ocean processes and the coastal processes are stark due to the influence of the bottom boundary layer and coastal wall in shallow water [ Glenn et al ., ; Seroka et al ., ]. It is critical to close this gap, with the goal of improving the simulation of coastal ocean physics in coupled TC intensity models [e.g., Zambon et al ., ; Warner et al ., ].…”

Autonomous and Lagrangian Ocean Observations for Atlantic Tropical Cyclone Studies and Forecasts

“…Under appropriate atmospheric conditions, TC intensification and weakening have been linked to ocean properties, such as upper-ocean heat content (Mainelli et al, 2008) and stratification , which can be estimated using both in situ and satellite observations. Assessment of the temperature of the upper 100 m of the ocean is linked to the amount of energy available for TC intensification (Price, 2009;D' Asaro et al, 2014;Glenn et al, 2016), together with other parameters, such as specific humidity and surface winds (Cione, 2015).…”

Ocean Glider Observations Around Australia

“…Gliders are typically deployed over periods of weeks to months, operate under a wide range of weather conditions, and provide high spatial and temporal resolution measurements (Glenn et al, 2016). Ocean glider deployments in Australia commenced in 2007 with the establishment of the Australian National Facility for Ocean Gliders (ANFOG) as part of the Integrated Marine Observing System (IMOS).…”