These projects were funded by the Indonesian Meteorology, Climatology, and Geophysics Agency (BMKG), the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) and the U.S. National Oceanic and Atmospheric Administration.
JAMSTEC has conducted field campaigns to evaluate the representativeness of the single-point mooring. The campaigns are focusing on the ocean and atmosphere interaction at the meso scale, by deploying multiple platforms around the research vessel for days. We accomplished two field campaigns in 2018 and 2020. In the pilot study in 2018, we stayed around our (13N, 137E) mooring for 4 days with a newly-deployed buoy and a buoy to be recovered (as in Fig. 1a). In 2020, we stayed around (12N, 135E) for 30 days and deployed a special short-term mooring and three unmanned vehicle “Wave Glider” (as in Fig. 1b). During this campaign, we captured the diurnal cycle of the ocean and atmosphere. In addition, the collaborative dual-Doppler observation with U.S. R/V Thompson during the PISTON field campaign was carried out successfully. Another field campaign to evaluate this concept is planned in 2021.
JAMSTEC conducted intensive observations of the ocean and atmosphere around the eastern part of the warm pool by R/V Mirai (MR20-01) cruise from February 23 to March 27, 2020. After capturing the zonal temperature and salinity gradients along the equator by an underway CTD, the intensive observation has been conducted by the R/V Mirai (~161.0˚E) with two Wave Gliders at the west (~158.0˚E) and east (~162.5˚E) of the sea surface temperature (SST) front from March 9 to 14 (Fig 2). During this campaign, we captured a drastic change in the ocean and atmosphere before and after the generation of the tropical depressions nearby. Additionally, we obtained oceanic and atmospheric structures by CTDO2/LADCP down to the depth of 500 dbar and radiosonde up to a height of 100 hPa.
Fig. 2: SST distribution at 12 March 2020 with positions of the R/V Mirai (0, 161.0˚E)and 2 Wave Gliders (0, 158.0˚E and 0, 162.5˚E)
Associated with YMC, the PISTON project by U.S. groups conducted a special field campaign from a research vessel deployed around 12°–17°N, 135°E in August-October 2018. JAMSTEC also conducted an observational cruise in the same region in August 2018, conducting special ocean-atmosphere observations. They both collaborated with each other. In addition to capturing detailed structure of air-sea processes including the diurnal cycle and meso-scale convective activity, dual-Doppler radar observations from shipboard polarimetric radars on the 2 research vessels successfully captured the fine three-dimensional structure of the precipitation systems. In addition to the Saildrone mission in 2018, an observational cruise was conducted in February-March 2020 with detailed air-sea measurements at a SST front in the eastern edge of the warm pool. Detailed air-sea structures at both sides of the front were observed. Analyses of the acquired data by these observations are now ongoing and some part of observational study is continued.
The detailed air-sea interaction processes were captured by the meso-scale network over the open ocean. As an example in Fig. 3, the vital and suppressed diurnal cycle of ocean and atmosphere were clearly captured before and after the generation of tropical depression (at Aug.24), at five platforms (R/V Mirai, a mooring, and three unmanned vehicles).
From the cruise in Feb.-Mar. 2020, the warm water at the west of the eastern edge migrated eastward through the substantial air-sea interaction, as evidenced by the coincidence of sea surface zonal current and wind anomaly directions from March 11 and 12 (Fig. 4) and active heat release from the ocean to the atmosphere. Besides, a Doppler radar installed on the R/V Mirai observed active convection along with the air-sea interaction (Fig. 5). It is suggested that monitoring for short-term variability associated with air-sea interactions need high-frequency multi-parameter observations.
JAMSTEC, 2018: Cruise Report MR18-04 Leg-2. Available from http://www.godac.jamstec.go.jp/catalog/doc_catalog/e/ .
JAMSTEC, 2020: Cruise Report MR20-E01. Available from http://www.godac.jamstec.go.jp/catalog/doc_catalog/e/ .
JAMSTEC, 2020: Cruise Report MR20-01. Available from http://www.godac.jamstec.go.jp/catalog/doc_catalog/e/ .
The raw data will be archived and opened from the JAMSTEC website. The QC’ed data are available upon request to the chief scientist of each cruise, and will be available in the future at a website currently being developed.