ECCO2 state estimate is obtained by using Green's function approach, ie,
by making optimal adjustment of model parameters, initial conditions, 
and boundary conditions (atmospheric forcing fields) through a series of
sensitivity numerical simulations and minimization of model/observation misfit.
The sensitivity experiments are named cube##, ranging from cube20 to cube90.
The data used to constrain the model includes sea surface height from
Topex/Poseidon, Jason-1, and Ocean Surface Topography Mission/Jason-2 satellite altimeters; 
ocean bottom pressure from Gravity Recovery and Climate Experiment (GRACE) mission; 
surface wind stress from QuikScat mission; sea surface temperature from the 
Advanced Microwave Scanning Radiometer-EOS (AMSR-E); sea ice concentration and velocity data 
from passive microwave radiometers (SSM/I); and temperature and salinity profiles 
from shipborne casts, moorings, and Argo ocean observation system.

The optimized model solution is cube92.
methodology:
	Using Green's functions to calibrate an ocean general circulation model
	http://ecco2.org/manuscripts/2005/green.pdf
infrastructure:	
	NASA supercomputer improves prospects for ocean climate research
	http://ecco2.org/manuscripts/2005/EOSecco.pdf
optimized solution:
	ECCO2: High resolution global ocean and sea ice data synthesis
	http://ecco2.org/manuscripts/reports/ECCO2_Mercator.pdf

================
Books with ECCO2: (future direction of ECCO or illustration of ocean current)
================
Modern Observational Physical Oceanography (2015)
	https://www.dropbox.com/s/t2b64mst5u74ehz/MOPO.pdf?dl=0
PDE Constrained Optimization (2017)
	https://www.dropbox.com/s/9xz1e2h5vjsbgpr/PED_constrained_optimization.pdf?dl=0
Underwater Acoustic Modeling Simulation (2018)
	https://www.dropbox.com/s/dgbiba0qxtkrl5k/Underwater_Acoustic_Modeling_Simulation.pdf?dl=0

Atmosphere, Ocean, and Climate Dynamics (2008)
	https://www.dropbox.com/s/dzj5cn4wckwjjge/atmos_ocean_dynamics.pdf?dl=0
Ocean Dynamics and Carbon Cycle (2011)
	https://www.dropbox.com/s/fv9zeawmr030goo/Ocean_Dynamics_Carbon_Cycle.pdf?dl=0
	more "Resources --> Animations | Figures" at
	https://www.cambridge.org/gb/academic/subjects/earth-and-environmental-science/oceanography-and-marine-science/ocean-dynamics-and-carbon-cycle-principles-and-mechanisms
Ocean Worlds (2014)
	https://www.dropbox.com/s/xbg2w0jejvsk7tl/ocean_worlds.pdf?dl=0
Robotics Research (Vol.2, 2018)
	https://www.dropbox.com/s/gzz17nkfb0udnln/Robotic_Research.pdf?dl=0

====================
Aniamtion with ECCO2:
====================
Surface current rendered on cube-sphere and globe
	https://www.youtube.com/watch?v=liohY282oi8
Earth From Space @PBS (from 46')
	http://www.pbs.org/video/nova-earth-space/
Perpetual Ocean @youtube
	https://www.youtube.com/watch?v=xusdWPuWAoU
Dynamic Earth @NASA Hyperwall (from 2'22'')
	https://svs.gsfc.nasa.gov/4469
Earth System @NASA Hyperwall
	https://svs.gsfc.nasa.gov/30701
Motions of Oceans @NASA Hyperwall
	https://svs.gsfc.nasa.gov/3912
Phytoplankton in Oceans @NASA Hyperwall
	https://svs.gsfc.nasa.gov/30669
CO2 Flux @NASA Hyperwall
	https://svs.gsfc.nasa.gov/4398
Garbage Patches @NASA Hyperwall
	https://svs.gsfc.nasa.gov/4174

=======================
Pubalication with ECCO2:
=======================
	400+ papers: typing "ecco2" in "search" box at
	https://ecco.jpl.nasa.gov/research/publications/


====================================================================
THIS product contains some essential fields from cube92 model output
interpolated (and for vectors rotated) onto 1/4-deg, 90S-90N conventional lat-lon grid
covering 1992/01/01 to 2019/03/31.
This ECCO2 output is mirrored at
http://apdrc.soest.hawaii.edu/datadoc/ecco2_cube92.php
 
The horizontal output grid is
latitude  = (-90+1/8) : (1/4) :  90
longitude =     (1/8) : (1/4) : 360

There are 50 vertical levels with thicknesses:
 delR   = 10.00, 10.00, 10.00, 10.00, 10.00, 10.00, 10.00, 10.01,
 10.03, 10.11, 10.32, 10.80, 11.76, 13.42, 16.04 , 19.82, 24.85, 
 31.10, 38.42, 46.50, 55.00, 63.50, 71.58, 78.90, 85.15, 90.18, 
 93.96, 96.58, 98.25, 99.25,100.01,101.33,104.56,111.33,122.83,
 139.09,158.94,180.83,203.55,226.50,249.50,272.50,295.50,318.50,
 341.50,364.50,387.50,410.50,433.50,456.50,

The output files are in netcdf files with
dimensions 1440*720 for 2D fields and 1440*720*50 for 3D fields.
2D fields are daily averages and 3D fields are 3-day averages.  
SSH.1440x720.19920101.nc  for daily mean SSH averaged on 1992/01/01
THETA.1440x720x50.19920102.nc for 3-day mean THETA 
averaged over 1992/01/01 to 1992/01/03.

THETA  		potential temperature (deg C)
SALT   		salinity (PSU)
SSH    		sea surface height (m)
UVEL   		zonal velocity (m/s)
VVEL   		meridional velocity (m/s)
PHIBOT		Bottom Pressure Pot. Anomaly (p/rhonil, m^2/s^2)
                To convert to m, divide by g (g=9.81 m/s^2)
		PHIBOT is the anomaly relative to Depth * rhonil * g
		The absolute bottom pressure in Pa is:
		Depth * rhonil * g + PHIBOT * rhonil (rhonil=1027.5 kg/m^3)