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Description

This dataset provides daily-averaged ocean and sea-ice surface freshwater fluxes on the native Lat-Lon-Cap 90 (LLC90) model grid from the ECCO Version 4 Release 4 (V4r4) ocean and sea-ice state estimate. Estimating the Circulation and Climate of the Ocean (ECCO) ocean and sea-ice state estimates are dynamically and kinematically-consistent reconstructions of the three-dimensional time-evolving ocean, sea-ice, and surface atmospheric states. ECCO V4r4 is a free-running solution of the 1-degree global configuration of the MIT general circulation model (MITgcm) that has been fit to observations in a least-squares sense. Observational data constraints used in V4r4 include sea surface height (SSH) from satellite altimeters [ERS-1/2, TOPEX/Poseidon, GFO, ENVISAT, Jason-1,2,3, CryoSat-2, and SARAL/AltiKa]; sea surface temperature (SST) from satellite radiometers [AVHRR], sea surface salinity (SSS) from the Aquarius satellite radiometer/scatterometer, ocean bottom pressure (OBP) from the GRACE satellite gravimeter; sea ice concentration from satellite radiometers [SSM/I and SSMIS], and in-situ ocean temperature and salinity measured with conductivity-temperature-depth (CTD) sensors and expendable bathythermographs (XBTs) from several programs [e.g., WOCE, GO-SHIP, Argo, and others] and platforms [e.g., research vessels, gliders, moorings, ice-tethered profilers, and instrumented pinnipeds]. V4r4 covers the period 1992-01-01T12:00:00 to 2018-01-01T00:00:00.

Product Summary

Platforms
MODELS ,
MITgcm
Spatial Extent

N: 90 S: -90 E: 180 W: -180

Spatial Resolution
1 Decimal Degrees x 1 Decimal Degrees
Location
GLOBAL OCEAN
Coordinate System
CARTESIAN
Granule Spatial Representation
CARTESIAN
Temporal Extent
1992-01-01 to 2018-01-01
Data Partner
Physical Oceanography Distributed Active Archive Center, Jet Propulsion Laboratory, NASA (NASA/JPL/PODAAC)
Concept ID
C1991543820-POCLOUD
Data State
COMPLETE
Number of Files/Granules
9497
Processing Level
4
Published
Science Keywords
Sublimation ,
Surface Precipitation ,
Evaporation ,
Runoff Rate ,
Snow ,
Fresh Water Flux

Citation

Citation is critically important for dataset documentation and discovery. This dataset is openly shared, without restriction, in accordance with the EOSDIS Data Use and Citation Guidance.

Copy Citation

Fenty, I., & Wang, O. (2020). ECCO Ocean and Sea-Ice Surface Freshwater Fluxes - Daily Mean llc90 Grid (Version 4 release 4) [Data set]. NASA Physical Oceanography Distributed Active Archive Center. https://doi.org/10.5067/ECL5D-FRE44 Date Accessed: 2026-03-15

Documents

Variables

The table below lists the variables contained within a single granule for this dataset. Variables often contain observed or derived geophysical measurements collected from a variety of sources, including remote sensing instruments on satellite and airborne platforms, field campaigns, in situ measurements, and model outputs. The terms variable, parameter, scientific data set, layer, and band have been used across NASA’s Earth science disciplines; however, variable is the designated nomenclature in NASA’s Common Metadata Repository (CMR). Variable metadata attributes such as Name, Description, Units, Data Type, Fill Value, Valid Range, and Scale Factor allow users to efficiently process and analyze the data. The full range of attributes may not be applicable to all variables. Additional information on variable attributes is typically available in the data, user guide, and/or other product documentation.

For questions on a specific variable, please use the Earthdata Forum.

Name Description Units Data Type Fill Value Valid Range Scale Factor Offset
EXFempmr Net surface freshwater flux from precipitation, evaporation, and runoff per unit area in open water (not covered by sea-ice). Excludes freshwater fluxes involving sea-ice and snow. Note: calculated as EXFevap-EXFpreci-EXFroff. m s-1 float 9.96921E+36 -8.299434E-5 to 5.4004213E-6 1 N/A
EXFevap Evaporation rate per unit area of open water (not covered by sea-ice). Note: calculated using the bulk formula following Large and Yeager (2004) NCAR/TN-460+STR. m s-1 float 9.96921E+36 -1.0958114E-6 to 7.0900546E-6 1 N/A
EXFpreci Precipitation rate. Note: sum of ERA-Interim precipitation and the control adjustment from ocean state estimation. m s-1 float 9.96921E+36 -1.4860395E-6 to 8.3177765E-5 1 N/A
EXFroff River runoff freshwater flux. Note: not adjusted by the optimization. m s-1 float 9.96921E+36 0 to 4.1856125E-5 1 N/A
i In the Arakawa C-grid system, tracer (e.g., THETA) and 'v' variables (e.g., VVEL) have the same x coordinate on the model grid. N/A int N/A N/A 1 N/A
i_g In the Arakawa C-grid system, 'u' (e.g., UVEL) and 'g' variables (e.g., XG) have the same x coordinate on the model grid. N/A int N/A N/A 1 N/A
j In the Arakawa C-grid system, tracer (e.g., THETA) and 'u' variables (e.g., UVEL) have the same y coordinate on the model grid. N/A int N/A N/A 1 N/A
j_g In the Arakawa C-grid system, 'v' (e.g., VVEL) and 'g' variables (e.g., XG) have the same y coordinate. N/A int N/A N/A 1 N/A
oceFWflx Net freshwater flux into the ocean including contributions from runoff, evaporation, precipitation, and mass exchange with sea-ice due to melting and freezing and snow melting. Note: oceFWflx does NOT include freshwater fluxes between the atmosphere and sea-ice and snow. The variable 'SIatmFW' accounts for freshwater fluxes out of the combined ocean+sea-ice+snow reservoir. kg m-2 s-1 float 9.96921E+36 -0.0391497 to 0.082994334 1 N/A
SFLUX The rate of change of total ocean salinity due to freshwater fluxes across the liquid surface and the addition or removal of mass. Note: the global area integral of SFLUX matches the time-derivative of total ocean salinity (psu s-1). Unlike oceFWflx, SFLUX includes the contribution to the total ocean salinity from changing ocean mass (e.g. from the addition or removal of freshwater in oceFWflx). g m-2 s-1 float 9.96921E+36 -0.73535776 to 0.106077336 1 N/A
SIacSubl Freshwater flux to the atmosphere due to sublimation-deposition of snow or ice. Positive values imply sublimation from ice/snow to vapor, negative values imply deposition from atmospheric moisture kg m-2 s-1 float 9.96921E+36 0 to 0.000815458 1 N/A
SIatmFW Net freshwater flux into the combined liquid ocean, sea-ice, and snow reservoirs from the atmosphere and runoff. Note: freshwater fluxes BETWEEN the liquid ocean and sea-ice or snow reservoirs do not contribute to SIatmFW. SIatmFW counts all fluxes to/from the atmosphere that change the TOTAL freshwater stored in the combined liquid ocean, sea-ice, and snow reservoirs. kg m-2 s-1 float 9.96921E+36 -0.0043017855 to 0.082994334 1 N/A
SIfwThru Precipitation over sea-ice covered regions reaching ocean through sea-ice. Note: Precipitation over sea-ice covered regions that directly reaches ocean through the sea-ice. It is not due to melt of sea-ice/snow. kg m-2 s-1 float 9.96921E+36 -0.00016952184 to 0.0106326295 1 N/A
SIrsSubl Residual freshwater flux by sublimation to remove water from or add water to ocean. When implied sublimation freshwater flux SIacSubl is larger than availabe sea-ice/snow, SIrsSubl is positive and water is removed from ocean. Note: freshwater flux by sublimation that is to remove water from the ocean when it is positive. kg m-2 s-1 float 9.96921E+36 -0.0010675289 to 8.6405336E-5 1 N/A
SIsnPrcp Snow precipitation on sea-ice kg m-2 s-1 float 9.96921E+36 -0.00043346695 to 0.0093540205 1 N/A
tile The ECCO V4 horizontal model grid is divided into 13 tiles of 90x90 cells for convenience. N/A int N/A N/A 1 N/A
time center time of averaging period hours since 1992-01-01T12:00:00 int N/A N/A 1 N/A
time_bnds Start and end times of averaging period. N/A int N/A N/A 1 N/A
XC nonuniform grid spacing degrees_east float N/A N/A 1 N/A
XC_bnds Bounds array follows CF conventions. XC_bnds[i,j,0] = 'southwest' corner (j-1, i-1), XC_bnds[i,j,1] = 'southeast' corner (j-1, i+1), XC_bnds[i,j,2] = 'northeast' corner (j+1, i+1), XC_bnds[i,j,3] = 'northwest' corner (j+1, i-1). Note: 'southwest', 'southeast', northwest', and 'northeast' do not correspond to geographic orientation but are used for convenience to describe the computational grid. See MITgcm dcoumentation for details. N/A float N/A N/A 1 N/A
XG Nonuniform grid spacing. Note: 'southwest' does not correspond to geographic orientation but is used for convenience to describe the computational grid. See MITgcm dcoumentation for details. degrees_east float N/A N/A 1 N/A
YC nonuniform grid spacing degrees_north float N/A N/A 1 N/A
YC_bnds Bounds array follows CF conventions. YC_bnds[i,j,0] = 'southwest' corner (j-1, i-1), YC_bnds[i,j,1] = 'southeast' corner (j-1, i+1), YC_bnds[i,j,2] = 'northeast' corner (j+1, i+1), YC_bnds[i,j,3] = 'northwest' corner (j+1, i-1). Note: 'southwest', 'southeast', northwest', and 'northeast' do not correspond to geographic orientation but are used for convenience to describe the computational grid. See MITgcm dcoumentation for details. N/A float N/A N/A 1 N/A
YG Nonuniform grid spacing. Note: 'southwest' does not correspond to geographic orientation but is used for convenience to describe the computational grid. See MITgcm dcoumentation for details. degrees_north float N/A N/A 1 N/A
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