SWOT will revolutionize oceanography by detecting ocean features with 10 times better resolution than present technologies. The higher resolution of SWOT is required to distinguish structures that occur on scales of 100 kilometers (62.1 miles) or shorter, where most of the ocean's energy is mixed and transported. Such small-scale ocean features contribute to the ocean-atmosphere exchange of heat and carbon, major components in global climate change. Moreover, SWOT's detailed information on ocean circulation will improve understanding of the ocean environment including motion of life-sustaining nutrients and harmful pollutants.
Fine-Scale Transport of Heat & Carbon
Currently, there is a poor understanding of fine-scale circulation where most of the ocean's motion-related energy is stored and lost. For example, SWOT will unveil unprecedented details about sub-mesoscale eddies. These ubiquitous, relatively short-lived, swirling currents are often "spun off" of major currents such as the Gulf Stream, whose larger (i.e., mesoscale) eddies have been revealed in satellite sea surface height and temperature maps for decades. Circulation at sub-mesoscales is thought to be responsible for transporting half of the heat and carbon from the upper ocean to deeper layers. Such downward ocean motion has helped to mitigate the decades-long rise in global air temperatures by absorbing and storing heat and carbon away from the atmosphere. Knowing more about this process is critical for understanding global climate change.
Predicting the Ocean Environment
Not only will SWOT's global measurements of small ocean features help to improve climate prediction models, these data will also reveal new details about the transport of many important substances. Some nutrients suspended in seawater are "essential ingredients" for microscopic plants and algae known as phytoplankton, which fuel the entire marine food web. Thus the distribution and transport of nutrients by currents and eddies is tied to the productivity of marine fisheries and the health of our living ocean.
Fine-scale ocean motion is also responsible for transporting pollutants such as crude oil, harmful river discharge, and debris (e.g., from tsunamis). Precisely tracking the location, speed and direction of potentially harmful materials will aid in natural hazard assessment, prediction, and response. In addition to modelling the dispersal of substances entrained in seawater, understanding the motion of water itself will be valuable. SWOT data will be used to improve ocean circulation forecasts, benefiting ship and offshore commercial operations, along with coastal planning activities such as flood prediction and sea level rise.
Featured Science Investigations
Assimilation and Interpretation of High-Wavenumber Variability in the Ocean for SWOT
(2017) PI: Sarah Gille
The objective of our research in support of SWOT is to develop 4-dimensional variational assimilation (4d-var) methods that include both quasi-geostrophic and tidal motions in order to build the capabilities to map, evaluate, and interpret SWOT observations, with a specific focus on the California Current region, which has been identified as one of the target regions for calibration and validation of SWOT (Wang et al., 2016). Our aim is to distinguish balanced, geostrophic motions from the myriad other processes that influence SSH variability at the ocean surface.
Calibration and Validation of SWOT Oceanographic Products Using the Permanent Facility for Altimetry Calibration in West Crete, Greece
(2017) PI: Stelios Mertikas
The main goal of this research is to answer these questions and carry out absolute calibration and validation (Cal/Val) of the SWOT products using the Permanent Facility for Altimetry Calibration (PFAC) in west Crete, Greece.
Characterization of Global Internal Tides at High Horizontal Resolution
(2017) PI: Samuel Kelly
This project aims to improve the prediction and characterization of internal-tide sea surface displacements using global numerical simulations with 1/100 (~1 km horizontal resolution. The high resolution simulations are conducted using the linearized Coupled-mode ShallowWater model (CSW; Kelly et al., 2016), which can resolve small-scale internal tides that are absent in coarserresolution general circulation models (which typically have horizontal resolutions of 4-10 km). The increased resolution improves the representation of internal tides throughout the global ocean, however the largest improvements occur in regions where internal tides have short wavelengths, such as coastal seas, regions of complex bathymetry, and areas of energetic mesoscale circulation.
Characterization, Modeling and SWOT Potentiality to Measure Hydro-Meteo-Marine Phenomena in the Coastal and Estuarine Systems
(2017) PI: Benoit Laignel
The main objective of the COTEST project (Characterisation, modeling and SWOT potentiality to measure hydro-meteo-marine phenomena in the coastal and estuarine systems) is to better understand the interactions of the hydro-meteo-marine phenomena on the hydrodynamics in the estuarine and coastal systems (nearshore and shoreline) and SWOT's ability to reproduce these hydrodynamics and phenomena.
Coastal Ocean Continuum in surface Topography Observations (COCTO)
(2017) PI: Nadia Ayoub and Pierre De Mey
This proposal will focus on three main objectives: Objective 1: Advance our understanding of fine-scale dynamical processes (O(1km) to O(10km)) within the estuary-mouth-plume-shelf-break-ocean continuum; Objective 2: Identify the signature of these processes in current and future measurements, in particular Sea-Surface height (SSH) and other surface measurements; and Objective 3: Characterize the potential impact of future SWOT measurements, together with complementary in situ measurements, on the estimation of those processes.
Developing an Effective Assimilation of SWOT Data in Mercator Ocean Systems (DESMOS)
(2017) PI: Pierre-Yves Le Traon
The main objective of our project is to prepare the assimilation of SWOT in Mercator Ocean and Copernicus Marine Environment Monitoring Service (CMEMS) high resolution ocean models. Assimilation of SWOT data together with conventional altimeter missions into ocean analysis and forecasting models is an essential and (most likely) mandatory step to develop a wide use of SWOT data for ocean applications.
Development of Calibration/Validation and Assimilation Methods of Wide-Swath Sea Surface Height Measurements in the Western North Pacific and Surrounding Marginal Seas
(2017) PI: Kai Matsui
In this proposal, based on our experience in observations and assimilation mainly in the western North Pacific and surrounding marginal seas, we will develop new observations for small scale sea surface height features, calibration and validation methods for SWOT, and SWOT data assimilation methods.
Exploiting Ocean Observations to Separate Mesoscale and Submesoscale Variability
(2017) PI: Kyla Drushka
A critical step in interpreting the SWOT signal will be to distinguish the mesoscale signals (wavelength > 50 km) from the other signals that will be detected by SWOT (e.g., submesoscale features, internal waves and tides, swell). This is a nontrivial problem, as these processes are not well understood or modeled. A further complication is that SWOT will have a temporal resolution of 10-20 days, making it difficult to identify the quickly evolving submesoscale field and internal waves. Tackling this problem requires a better understanding of ocean dynamics across the range of scales and regimes that SWOT will measure.
Fluxes of Heat, Carbon, and Oxygen at SWOT Scales
(2017) PI: Shafer Smith
There are many complex issues involved in maximizing the usefulness of SWOT observations. Our particular focus is on better understanding how SWOT may aid in better establishing the role played by submesoscale phenomena in mediating fluxes of the biogeochemical tracers. Can SWOT help determine submesoscale contributions to global budgets? What are the primary lateral and temporal scales responsible for transport? Which submesoscale processes play the most important roles in vertical fluxes? We are addressing these questions with suites of submesoscale-resolving regional simulations, described briefly in this document.
Mesoscale and Sub-Mesoscale Vertical Exchanges from Multi-platform Experiments and Supporting Modeling Simulations (MULTI-SUB)
(2017) PI: Ananda Pascual
The general objective of MULTI-SUB is to quantify and improve our and understanding of vertical exchanges associated with oceanic mesoscale and sub-mesoscale features (e.g fronts, meanders, eddies and filaments) through the combined use of, in-situ and satellite data in synergy with numerical models. The ultimate goal is to enhance our understanding of the impact of finescale processes on biochemical variables. We will focus on a range of scales (30-100 km) traditionally not resolved by conventional altimeters.
Modeling Internal Wave Signals and their Predictability for SWOT
(2017) PI: Brian Arbic
We are working with high-resolution global simulations, of the HYbrid Coordinate Ocean Model (HYCOM) and the MITgcm, that are simultaneously forced by atmospheric and oceanic fields and that therefore resolve both mesoscale eddies and internal wave motions.
New Dynamical Tools for Submesoscales Characterization in SWOT Data
(2017) PI: Guillaume Lapeyre
The altimetry mission SWOT will provide Sea Surface Height (SSH) data-sets at unprecedented resolution (10-100km) with a 2D coverage in space. Such a data-set requires development of new diagnostic tools to unveil different dynamical aspects of the mesoscales (horizontal scales around 300km) and submesoscales (around 30km) that can be extracted from the SSH signal.
Ocean Mesoscale, Sub-mesoscale, and Internal Wave Variability and Dynamics
(2017) PI: Roger Samelson
The overall project goals are to assess how oceanic mesoscale, sub-mesoscale, and internal wave signals may be manifest in SWOT measurements and how to use SWOT data to develop new physical insight into these phenomena, and to contribute to addressing the associated challenges posed to the SWOT mission.
OSIRIS: Ocean, Sea-ice and Rain Investigations for SWOT
(2017) PI: Francesco Nencioli
The OSIRIS project brings together the work plans of seven investigators from five UK organizations. The consortium gathers a broad range of UK expertise which will contribute to different aspects of SWOT research priorities for oceanography and cryosphere.
Participation in the SWOT Science Team: Marine Geophysics
(2017) PI: David Sandwell
One of the secondary objectives of the SWOT mission is marine geophysics. The current accuracy of the ocean surface slope derived from traditional altimetry is about 2 microradians at 13 km wavelength, which is equivalent to 2 milligals of accuracy. SWOT, with its smaller footprint and additional cross-track slope measurement, could improve the gravity accuracy by perhaps an order of magnitude and also improve spatial resolution especially on the shallow continental margins.
Research and Development of SWOT Measurements in the Canadian Oceans
(2017) PI: Guoqi Han
The scientific objectives for this proposal are (1) to improve knowledge of coastal currents, mesoscale and submesoscale features, tides, marine winds and waves from existing nadir altimetry data, RADARSAT images, in situ measurements and numerical models in Canadian marine waters, and (2) to improve models for tide, circulation, internal tide and wave, and surface wave and to develop techniques that can effectively integrate simulated SWOT data into these models.
SPAce altimetry for Water and Energy Transfers modeling (SPAWET)
(2017) PI: Catherine Ottlé
The overall objective of the SPAWET project is to improve the characterization and modelling of lakes and groundwater buffering impacts based on the use of future SWOT data. For that purpose, we propose to develop and apply advanced and complementary hydrological models and to explore the potential of SAR altimetry for enhancing their performances. These developments will therefore improve the overall simulation of the hydrological cycle through a better quantification of lake evaporation and groundwater contribution to river discharges.
SWOT and the Ice-Covered Oceans of the Arctic and Antarctic: Sea Surface Height and Sea Ice Freeboard
(2017) PI: Ronald Kwok
This project addresses research opportunities offered by the SWOT mission that pertain to observations of sea surface height and sea ice freeboard/thickness of the ice-covered oceans.
SWOT in the Tropics: A Case Study in the South West Pacific
(2017) PI: Lionel Gourdeau
This proposal aims at federating people from different communities working on climate, turbulence, models and observations in order to investigate how the high-resolution and high-frequency (1-day) measurements of SWOT could be dynamically interpreted and used in the tropics. The ultimate purpose is to propose for the next SWOT call a cal/val experiment based on the results of this proposal.
Transition Scale from Geostrophic Flows to Wave Motions in the World Ocean
(2017) PI: Bo Qiu
The overall goals of our project as part of the SWOT Science Team are, (1) to aid SWOT mission science preparation by evaluating spatio-temporal variability of SSH and surface velocity signals from available repeat ship-board ADCP measurements and high-resolution OGCM output from 1/48° MITgcm (llc 4320), and, (2) to advance our understanding of new upper ocean dynamics at O(5-200km) scales by analyzing high-resolution OGCM output and ADCP data, with the goal to maximize SWOT's scientific return.