Saildrone-observed atmospheric boundary layer response to winter mesoscale warm spot along the Kuroshio south of Japan

Abstract

Using an unmanned sailing vehicle, known as a Saildrone, we observed mesoscale and smaller scale structures of oceanic and atmospheric variables across the Kuroshio south of Japan during the winter of 2018/2019. From December 28 to December 29, 2018, the Saildrone crossed just north of the center of a very warm (∼23 • C) mesoscale spot in the Kuroshio centered around 31.5 • N, 135.8 • E. The northerly winter monsoon wind was intensified by ∼2 m s −1 over the mesoscale warm spot (MWS) and accompanied by a submesoscale sea level pressure undulation of ∼1 hPa possibly due to two oppositely rotating ageostrophic vortices. At this time, the wind reached a maximum speed of greater than 12 m s −1 and removed heat from the ocean at a rate of 1141 W m −2. Subsequently (January 3-5, 2019), the Saildrone observed weakening of wind and heat release to the atmosphere on the southern edge of the MWS, which was associated with the approaching low-pressure system over the Kuroshio. The observed submesoscale structures of atmospheric and oceanic variables near the center of the MWS suggest that the atmospheric boundary layer responded to the MWS through the pressure adjustment mechanism in the Kuroshio, where in situ high-resolution measurements have not been performed before.

Coupled Atmosphere–Ocean Variations on Timescales of Days Observed in the Western Tropical Pacific Warm Pool During Mid‐March 2020

“…Following Nagano and Ando (2020), we decomposed the anomalies of the LHF, Δ F L , from the mean values during the observation period into the components of SST, atmospheric temperature, specific humidity, and wind speed at the sea level as $$${\Delta}{F}_{\mathrm{L}}\,\approx \,\left(\frac{\partial {F}_{\mathrm{L}}}{\partial {T}_{\mathrm{S}}}\right){\Delta}{T}_{\mathrm{S}}+\left(\frac{\partial {F}_{\mathrm{L}}}{\partial {T}_{\mathrm{A}}}\right){\Delta}{T}_{\mathrm{A}}+\left(\frac{\partial {F}_{\mathrm{L}}}{\partial q}\right){\Delta}q+\left(\frac{\partial {F}_{\mathrm{L}}}{\partial U}\right){\Delta}U,$$$ where Δ T S , Δ T A , Δ q , and Δ U are temporal variations in SST, atmospheric temperature, specific humidity, and wind speed, respectively. In this study, each term of the RHS of Equation was computed using the bulk flux algorithm (Fairall et al., 2003) and setting other variables to their mean values during the observation period.…”

“…Following Nagano and Ando (2020), we decomposed the anomalies of the LHF, ΔF L , from the mean values during the observation period into the components of SST, atmospheric temperature, specific humidity, and wind speed at the sea level as…”

Toward Long-Term Sailing Robots: State of the Art From Energy Perspectives

“…A large number of applications have adopted Saildrones, such as marine mammals and fishes observation ( Mordy et al, 2017 ; Stierhoff et al, 2019 ; De Robertis et al, 2019 ; Kuhn et al, 2020 ), acidification observation ( Tilbrook et al, 2019 ), cold pools observation ( Wills et al, 2021 ), surface temperature and salinity gradients observation ( Vazquez-Cuervo et al, 2020 ; Vazquez-Cuervo et al, 2021 ), ocean CO 2 observation ( Sutton et al, 2021 ; Marouchos et al, 2018 ; Sabine et al, 2020 ), climate observation ( Meinig et al, 2019) ; Gentemann et al, 2020 ; Nagano and Ando, 2020 ), satellite ocean evaluation ( Scott et al, 2020 ; Meinig et al, 2015 ; Cokelet et al, 2015 ), gas or oil seep detection ( Scoulding et al, 2020 ; Daneshgar Asl et al, 2017 ), harsh environment exploration ( Chiodi et al, 2021 ), and ice zone observation ( Chiodi et al, 2021 ).…”

Atmospheric Fronts Shaping the (Sub)Mesoscale SST‐Wind Coupling Over the Southern Ocean: Observational Case

“…In recent years, Saildrone (Uncrewed Surface Vehicle, Figure 1a) exhibits the potential to conduct measurements of the upper ocean and lower atmosphere layer in severe conditions (D. Zhang et al., 2019; Vazquez‐Cuervo et al., 2019; Gentemann et al., 2020; Nagano & Ando, 2020; Sutton et al., 2020; Reeves Eyre et al., 2023). These new features recorded by Saildrone can improve our understanding of fine‐scale air‐sea interaction and refine the parameterization in numerical weather models.…”