Global in situ Observations of Essential Climate and Ocean Variables at the Air–Sea Interface

Abstract

The air-sea interface is a key gateway in the Earth system. It is where the atmosphere sets the ocean in motion, climate/weather-relevant air-sea processes occur, and pollutants (i.e., plastic, anthropogenic carbon dioxide, radioactive/chemical waste) enter the sea. Hence, accurate estimates and forecasts of physical and biogeochemical processes at this interface are critical for sustainable blue economy planning, growth, and disaster mitigation. Such estimates and forecasts rely on accurate and integrated in situ and satellite surface observations. High-impact uses of ocean surface observations of essential ocean/climate variables (EOVs/ECVs) include (1) assimilation into/validation of weather, ocean, and climate forecast models to improve their skill, impact, and value; (2) ocean physics studies (i.e., heat, momentum, freshwater, and biogeochemical air-sea fluxes) to further our understanding and parameterization of air-sea processes; and (3) calibration and validation of satellite ocean products (i.e., currents, temperature, salinity, sea level, ocean color, wind, and waves). We review strengths and limitations, impacts, and sustainability of in situ ocean surface observations of several ECVs and EOVs. We draw a 10-year vision

Ship-Based Contributions to Global Ocean, Weather, and Climate Observing Systems

“…The authors recommend establishing routine communication between ship-and autonomous surface vessel-based science communities to develop and disseminate techniques between their domains, as an optimum ocean observational network is multi-platform. We expect autonomous surface vessels to play an ever-growing role in ocean observations for a variety of disciplines as new sensors become integrated (e.g., air-sea fluxes, ocean biogeochemistry, and fisheries; Swart et al, 2016;Centurioni et al, 2019). The role of the autonomous surface vessels to enhance and broaden existing and future shipbased observing needs to be defined.…”

Ocean Observations in Support of Studies and Forecasts of Tropical and Extratropical Cyclones

“…During the Atlantic hurricane season, for example, Surface Velocity Program (SVP), Surface Velocity Program Barometer (SVPB) and Autonomous Drifting Ocean Station drifters (Centurioni, 2010; see also Centurioni, 2018, for a complete description of the drifter technology) are often airdeployed in front of TCs that may impact the US mainland. New drifters capable of measuring the directional wave spectra of surface gravity waves, termed Directional Wave Spectra Drifters (Centurioni et al, 2016(Centurioni et al, , 2019 have also been deployed ahead of TCs. Successful deployments of various drifters have been carried out in the Atlantic Ocean during the following TCs: Fabian (2003) (2010).…”

“…In addition, drifters that are part of the Global Drifter Program 6 array, often come close to TCs and provide valuable SST and SLP observations. In the 2013-2018 period a total of 116 SVP and SVPB drifters were located within 55 km of the tracks of systems that eventually developed into hurricanes (Centurioni et al, 2019). However, the effect of SLP drifter observation in improving TC track forecast has yet to be studied.…”

“…Analysis of ocean observations from the largely climate-focused ocean observing system often provides valuable information on the mechanisms and processes associated with these extreme weather conditions. Ocean data in support of extreme weather events need to focus on resolving upper ocean features such as barrier layers, spatial variability of warm currents, mesoscale OHC changes, and surface waves (Centurioni et al, 2019) prior to and during the season in each basin where TCs occur, with distribution of data in real-time. However, the scientific and operational requirements of observing platforms, such as profiling floats (Roemmich et al, 2019), moorings (Foltz et al, 2019;Masumoto et al, 2019;Smith et al, 2019), and expendable probes , do not explicitly target these needs.…”

Observing the Oceans Acoustically

“…Multipurpose acoustic systems can provide ground-truth for ecosystem modeling and forecasting. Acoustic in situ rainfall and wind speed estimates can improve our observations of air-sea fluxes (Centurioni et al, 2019), particularly in sparely sampled regions such as the Southern Ocean (Swart et al, 2019) and polar regions (Smith et al, 2019) as well as improve our ability to monitor wind/current/wave interactions (Villas Bôas et al, 2019). The direct estimates of ocean state variables from acoustic tomography and acoustically located and navigated autonomous platforms operating in undersampled high-latitude regions will improve ocean state estimation (Heimbach et al, 2019).…”