Asymmetric air-sea heat flux response and ocean impact to synoptic-scale atmospheric disturbances observed at JKEO and KEO buoys

Abstract

This study aims to identify patterns of surface heat fluxes, and corresponding surface ocean responses, associated with synoptic-scale atmospheric events and their modulation on seasonal time scales. In particular, northerly and southerly wind events associated with atmospheric disturbances were analyzed using high-temporal resolution time-series data from two moored buoys (JKEO: 2007–2010 and KEO: 2004–2019) north and south of the Kuroshio Extension current. Although each synoptic-scale wind event generally impacted both sites, the composite surface heat flux was larger at the northern site, especially for northerly events. Both types of wind events were observed throughout the year, with a minimum during June-July–August. Northerly wind events tended to be accompanied by lowered air-temperature, while southerly events tended to have elevated air-temperature relative to the previous three days. The resulting anomalous surface heat loss was asymmetric, with larger changes in northerly events compared to the southerly events. A large and significant ocean response of − 0.28 to − 0.46 K (p-value < 0.05) in SST was confirmed only for northerly events in spring–summer at the northern site, while smaller changes were found at the southern site. The results of this study suggest that sub-monthly air-sea interactions may affect seasonal variability and potentially climate change over longer timescales.

The Synoptic and Interannual Variability of Extreme Turbulent Heat Flux Events During Austral Winter in the Southern Indian Ocean

“…After losing a large amount of heat, that is the buoyancy, the stratification of the ocean would be changed to result in deep convection (DuVivier et al., 2016; Moore et al., 2014). Based on the observation and reanalysis dataset, the turbulent flux induced by synoptic disturbances can influence the SST and MLD (Tomita et al., 2021; Yu et al., 2020). Our results point out the accumulated THF can lead to deep mixed layer between 60° and 90°E, corresponding to the major subduction region (J. Ma & Lan, 2017; Sallée et al., 2010), which may contribute to the formation of subantarctic mode water due to lateral induction over the MLD front (Zhang et al., 2021).…”

“…Therefore, the surface wind speed must have an impact on the excitement of extreme THF events. Recent study has mentioned that the contribution of wind speed to the intermittently enhanced THF under the impact of large meridional wind variance is secondly large, when compared to the contribution of air temperature and humidity (Tomita et al., 2021). Whereas, the filtered SST does not show a wavy structure like other atmospheric variables (not shown), due to the deep mixed layer depth and the thermal advection effect by strong current.…”

“…Furthermore, the cyclone‐anticyclone interaction zone is regarded as the key role in forming extreme surface fluxes (N. Tilinina et al., 2018), which is also referred to as cold air outbreaks, with cyclones bringing relative cold and dry air to warm ocean surface (Rudeva & Gulev, 2011; N. D. Tilinina et al., 2016). Under the effect of synoptic scale THF, previous studies have pointed out the high frequency upper ocean variability, including mixed layer depth (MLD) and SST (Oka et al., 2007; Qiu et al., 2004; Tomita et al., 2021). Moreover, the atmospheric circulation variability contributes to the occurrence of extreme flux events on the interannual time scales (Kim et al., 2016; X. Ma et al., 2015).…”

Ocean Surface Warming and Cooling Responses and Feedback Processes Associated With Polar Lows Over the Nordic Seas

“…To elucidate the causes of variation in the surface THF calculated using the bulk formula, we investigated the factors of variation in each bulk variable using the linearized bulk equation (Tanimoto et al., 2003; Tomita, Cronin, & Ohishi, 2021). The surface THF was calculated as the sum of LHF and SHF.…”

Recent Sensing Technologies of Imperceptible Water in Atmosphere

“…Using the same detection principle, buoys of several types associated with proper humidity sensors could be allocated at several sea stations and detect the wind speed and direction correlated with the temperature and humidity levels. Thus, one can estimate the surface heat flux corresponding to the sea surface [158].…”