1. Summary of Winds and Currents from Satellite Meeting April 19 and 20, 2018
Mark A. Bourassa1 Ernesto Rodriguez2 and Sarah Gille3
Center for Ocean-Atmospheric Prediction Studies and Department of Earth, Ocean and Atmospheric Science, Florida State University
2. JPL/Caltech
3. Scripps Institution of Oceanography

2. Designated Measurements
Atmospheric
Boundary Layer?
GRACE Follow-on

3. Competed Concepts Winds and Currents
Opportunities for 3 of 6 to be selected in coming decade
Possibility that other concepts needing tech development could also be ready for competition by end of decade, so maybe 3 of 7 or 3 of 8.
Competed between science objectives
Community buy-in a must
Needs to address a wide scope of science and applications

4. Questions to esas2017@nas.edu
WACM opportunities
Questions to

5. Goals of Meeting
We must develop science topics (or topic) that sound exciting to more than oceanographers. We must develop the measurement requirements for these science topics.
The orbit selection and instrument design can be refined later to be optimized for the research goals.
A past point design (WaCM) for an Earth Ventures mission had roughly 5km spatial scales, 1600km swath width, 0.8 m/s uncertainty in winds, and 0.5 m/s uncertainty in currents
This design had to meet specific budget and accommodation constraints and address a single science hypothesis
Our new design can be optimized based on science goals
Identify potential issues that will need to be addressed
Communicate the benefits to the science and applications communities and decision makers
Publications and outreach
Produce a white paper eventually resulting in an refereed publication

6. Suggested Science Goals
Broad theme of Improved Air-Sea Coupling
Improving representation of the interface between the ocean and the atmosphere as well as the atmospheric and oceanographic boundary-layers
Suggested Specific Topics
Improved understanding of the tropical ocean circulation
Improved seasonal to interseasonal forecasting
Improved air-sea interaction associated with eddies and currents
Links to ocean and weather forecasting
Strong links to ocean biological
Ocean-atmosphere-sea ice coupling
Links to changes in Arctic and ocean circulation

7. Winds and Currents Applications
The observations required for the science topics would greatly benefit ocean observing systems
TPOS2020 and AtlantOS, among others
The in situ observing system would help validate some of the science goals related to mixed layer variability and ocean circulation (tropical and Arctic
There are many applications that help the business case
Ship routing
Weather forecasting
Fisheries management
Glacier and sea ice tracking
Agriculture (based on longer-term forecasts)
Forecasting of severe weather
More….

8. Steps to Move Forward Get a better name that WaCM
Pin down science objectives – and clearly articulate them
Verify that there are not serious problems with rain and aliasing of inertial, tidal and diurnal cycles
Optimize instrument characteristics with respect to the science goals
The aircraft instrument works better than expected, so we have some trade space with the instrument design
Develop modeling of the boundary-layers
This would allow for better use of the winds and currents observations
Improved surface physics, winds and currents would put much stronger constraints on entrainment at the top of the atmospheric boundary-layer
Likely improving the assimilation of surface winds

9. General Concept Behind the Goal
The ocean and atmosphere are relatively strongly coupled on scales below about 70km
Far more so that seen in one-way coupled models
The spatial derivatives of currents and directional wind (stress) show a strong signal.
Coupled models will need to represent this coupling to properly describe the energy and water cycle, as well as ocean forcing
Desired Outcome
To characterize the coupling between current gradients and the curl of the wind (stress) as a function of spatial scale and current gradient.
This will provide critical information for two-way coupled ocean-atmosphere models, the future of modeling.
Graphic created by WHOI

10. Ocean’s Vertical Heat Flux Due to Submesoscale Variability
Graphic from Ocean submesoscales as a key component of the global heat budget by Zhan Su, Jinbo Wang, Patrice Klein, Andrew F. Thompson & Dimitris Menemenlis

11. Upper-ocean heat content rate of change
Upper-Ocean Heat Content Rate of Change - Modern Model vs data - Seas Around Antarctica
Upper-ocean heat content rate of change
Modern Model
A smattering of other Argo and air-sea heat flux-related results 6.  Air-sea fluxes in the Southern Ocean explain the annual cycle in upper ocean heat content when you average over the entire Southern Ocean, but don't explain the local balances.  Net temperature change of the Southern Ocean is consistent with about 0.6 W/m^2 input over the last 50 years; net freshening consistent with increased precipitation or ice melt.
Gille et al, in prep (Presentation at Ocean Sciences Meeting)
Models (left) don’t match observations (right)
Except when averaged over the whole Southern Ocean
If regional energy budgets are wrong, heating will occur in the wrong areas and air-sea exchange will be non-sense
Sarah Gille

12. Summary
The curl of wind (stress) as a function of the gradient of surface current is a strong indicator of small scale (low end of mesoscale, <75 km) coupling between the ocean and atmosphere
We can diagnose this coupling with WaCM Geophysical variables
This coupling appears to be relatively important for the regional and global energy and water cycles, as well as ocean forcing
We can greatly improve tropical coupling and identify the tropical general circulation
Surface mMeridonal circulation can be observed with high confidence for the first time
Ice motion couple with flow around ice and stress around ice can be observed.
Many applications, including data assimilation.