Overview of PHSMO

  In key areas such as the equatorial and Kuroshio regions where the ocean and atmosphere variations play critical roles in the climate system, monitoring systems using moored buoys have been initiated and maintained. On the basis of the knowledge obtained from the buoy array data, we further noticed that, in the Philippine Sea, there are other possible key areas where the variations are responsible for phenomena in the equatorial and Kuroshio regions such as El Niño and the southern Oscillation (ENSO) (Hasegawa and Hanawa, 2007) and ENSO-related salinity variation of the sea surface Kuroshio water (Nagano et al., 2014, 2017). Also, other atmospheric and oceanic disturbances on various timescales such as typhoons, cold surges, seasonal march of the East Asian monsoon, and Madden-Julian Oscillation are present in the Philippine Sea (Nagano et al., 2018). Therefore, to further understand the air-sea interaction in the western North Pacific, JAMSTEC deployed a moored buoy at a site east of the Philippines (nominal 13˚N, 137˚E), corresponding to the northern edge of the western Pacific warm pool, and named PHSMO (Philippine Sea mooring) from December 2016.

Map of sea surface temperature (◦C) in the western tropical and northern subtropical Pacific in February 2017 from monthly NOAA Optimum Interpolation Sea Surface Temperature V2 data (Reynolds et al., 2007). Contour interval is 2 ℃. KEO and PHSMO sites are indicated by stars.

  This buoy is based on the m-TRITON buoy, deploying eastern Indian Ocean (Ueki et al., 2010), and K-TRITON buoy, which had been deployed in the Kuroshio Extension region from February 2008 to July 2013 (http://www.jamstec.go.jp/iorgc/ocorp/ktsfg/data/jkeo/index.html). The atmospheric and oceanic data observed by the buoy are publicly available in this web site.


  • Hasegawa, T. and K. Hanawa: Upper ocean heat content and atmospheric anomaly fields in the off-equatorial North Pacific related to ENSO, J. Oceanogr., 63, 561–572, 2007.
  • Nagano, A., K. Uehara, T. Suga, Y. Kawai, H. Ichikawa, and M. F. Cronin: Origin of near-surface high-salinity water observed in the Kuroshio Extension region, J. Oceanogr., 70, 389–403, 2014.
  • Nagano, A., T. Hasegawa, I. Ueki, and K. Ando: El Niño–Southern Oscillation-time scale covariation of sea surface salinity and freshwater flux in the western tropical and northern subtropical Pacific, Geophys. Res. Lett., 44, 6895–6903, 2017.
  • Nagano, A., I. Ueki, T. Hasegawa, and K. Ando: Ocean-atmosphere obserations in Philippine Sea by moored buoy, 2018 OCEANS - MTS/IEEE Kobe Techno-Oceans (OTO), 1-6, 2018
  • Reynolds, R.W, T. M. Smith, C. Liu, D. B. Chelton, K. S. Casey, M. G. Schlax: Daily high-resolution-blended analyses for sea surface temperature. J. Climate 20, 5473–5496, 2007.
  • Ueki, I. N, Fujii. Y, Masumoto. and K, Mizuno: Data evaluation for a newly developed slack-line mooring buoy deployed in the eastern Indian Ocean. J. Atmos. Oceanic Technol., 27, 1195–1214, 2010.

Dr. Iwao Ueki
E-mail uekii [at] jamstec.go.jp