Remote subsurface ocean temperature as a predictor of Atlantic hurricane activity

Abstract

Predicting North Atlantic hurricane activity months in advance is of great potential societal significance. The ocean temperature, both in terms of North Atlantic/tropical averages and upper ocean heat content, is demonstrated to be a significant predictor. To investigate the relationship between the thermal state of the Atlantic Ocean and the tropical cyclone (TC) activity in terms of accumulated cyclone energy (ACE), we use observed 1980–2015 TC records and a 1/4° resolution global ocean reanalysis. This paper highlights the nonlocal effect associated with eastern Atlantic Ocean temperature, via a reduction of wind shear, and provides additional predictive skill of TC activity, when considering subsurface temperature instead of sea surface temperature (SST) only. The most active TC seasons occur for lower than normal wind shear conditions over the main development region, which is also driven by reduced trade wind strength. A significant step toward operationally reliable TC activity predictions is gained after including upper ocean mean temperatures over the eastern Atlantic domain. Remote effects are found to provide potential skill of ACE up to 3 months in advance. These results indicate that consideration of the upper 40-m ocean average temperature improves upon a prediction of September Atlantic hurricane activity using only SST.

Projected Future Changes in Tropical Cyclones Using the CMIP6 HighResMIP Multimodel Ensemble

“…The frequency (count per year) is the simplest metric of TC activity but is strongly sensitive to the tracking algorithm, model resolution, observing system changes, and other aspects (Roberts et al, 2020). The ACE index (Bell et al, 2000) is an integrated measure of TC activity, and its variability is more robust (Scoccimarro et al, 2018; Villarini & Vecchi, 2013; Zarzycki & Ullrich, 2017). We use the same method as Camp et al (2015) and calculate ACE throughout the lifetime of each model storm during its warm core phase using winds at 925 hPa.…”

Projected Future Changes in Tropical Cyclones using the CMIP6 HighResMIP Multi-model Ensemble

“…The frequency (count per year) is the simplest metric of TC activity but is strongly sensitive to the tracking algorithm, model resolution, observing system changes, and other aspects (Roberts et al, 2020). The ACE index (Bell et al, 2000) is an integrated measure of TC activity, and its variability is more robust (Scoccimarro et al, 2018;Villarini & Vecchi, 2013;. We use the same method as Camp et al (2015) and calculate ACE throughout the lifetime of each model storm during its warm core phase using winds at 925 hPa.…”

The Importance of Marine Research Infrastructures in Capturing Processes and Impacts of Extreme Events

“…On the short time scale, an important role is played by observational systems such as radiosondes, coastal weather radars and reconnaissance flights, also due to their contribution in providing the detailed initial environmental state description necessary for modeling TC development. A recent work (Scoccimarro et al, 2018) demonstrated the importance of the subsurface temperature in modulating TC activity on seasonal time scales, specifically its fundamental role of monitoring of the eastern Atlantic sector (in red in Figure 4). Moving from short to seasonal and even longer time scales, an important role is played by the ocean since the main source of energy for TC development resides in this "compartment" of the climate system.…”