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Description

This dataset provides daily-averaged model-simulated ocean density and hydrostatic pressure from the SASSIE ECCO Version 1 Release 1 (V1R1) ocean and sea-ice state estimate. ECCO (Estimating the Circulation and Climate of the Ocean) is a 4D ocean circulation model combining observations with a general circulation model (GCM) to estimate the complete time-evolving state of the global ocean. In this project, it was run over the Arctic polar region in support of the Salinity and Stratification at the Sea Ice Edge (SASSIE) field experiment - a NASA experiment focused on salinity anomalies in the upper ocean generated by melting sea ice. The SASSIE ECCO simulation was produced by downscaling the global ECCO state estimate from 1/3 to 1/12 degree grid cells, where the global solution provided initial and boundary conditions and atmospheric forcing. The output fields for this dataset cover the period 2014-01-15T12:00:00 to 2021-02-07T12:00:00 and are consolidated onto a single curvilinear grid face focusing on the Arctic domain, using the 5 faces of the lat-lon-cap 1080 (llc1080) native grid from the original simulation. Ocean density and pressure are provided at 90 depth levels from 0.5 meters to 6760 meters. Daily files are available in netCDF-4.
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This dataset is one of 22 produced by SASSIE ECCO - the full list can be found in the user guide. To cite all 22 datasets with a single DOI, please cite the user guide (citation details and DOI can be found within the user guide).

Version Description

Version 1, Release 1

Product Summary

Platforms
MITgcm
Location
ARCTIC
Coordinate System
GEODETIC
Granule Spatial Representation
GEODETIC
Temporal Extent
2014-01-15 to 2021-02-08
Temporal Resolution
1 Day
Vertical Extent
Maximum Depth: 6760<br>Minimum Depth: 0.5
Data Partner
Physical Oceanography Distributed Active Archive Center, Jet Propulsion Laboratory, NASA (NASA/JPL/PODAAC)
Concept ID
C3675524854-POCLOUD
Data State
COMPLETE
Number of Files/Granules
2581
Processing Level
4
Science Keywords
Water Pressure ,
Density

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

Marie Zahn, M. W. (2026). SASSIE ECCO Ocean Density and Hydrostatic Pressure - Daily Mean llc1080 Grid (Version 1 Release 1) [Data set]. NASA Physical Oceanography Distributed Active Archive Center. https://doi.org/10.5067/SEL1D-ODE11 Date Accessed: 2026-01-29

Documents

Variables

Variables are a set of physical properties whose values determine the characteristics or behavior of something. For example, temperature and pressure are variables of the atmosphere. Parameters and variables can be used interchangeably. Variable level attributes provide individual information for each variable.

The Name in this table is the variable name. Fill value indicates missing or undefined data points in a variable. Valid range is the range of values the variable can store. Scale factor is used to increase or decrease the size of an object and can be used to correct for distortion. For questions on a specific variable, please use the Earthdata Forum.

Name Description Units Data Type Fill Value Valid Range Scale Factor
i In the Arakawa C-grid system, tracer (e.g., THETA) and &#039;v&#039; variables (e.g., VVEL) have the same x coordinate on the model grid. N/A int N/A N/A 1
j In the Arakawa C-grid system, tracer (e.g., THETA) and &#039;u&#039; variables (e.g., UVEL) have the same y coordinate on the model grid. N/A int N/A N/A 1
k grid index in z for tracer variables N/A int N/A N/A 1
k_l First index corresponds to the top face of the uppermost tracer grid cell. The use of &#039;l&#039; in the variable name follows the MITgcm convention for naming the top face of ocean tracer grid cells. N/A int N/A N/A 1
k_p1 Includes top of uppermost model tracer cell (k_p1=0) and bottom of lowermost tracer cell (k_p1=91). N/A int N/A N/A 1
k_u First index corresponds to the bottom face of the uppermost tracer grid cell. The use of &#039;u&#039; in the variable name follows the MITgcm convention for naming the bottom face of ocean tracer grid cells. N/A int N/A N/A 1
PHIHYD PHIHYD = p(k) / rhoConst - g z*(k,t), where p = hydrostatic ocean pressure at depth level k, rhoConst = reference density (1027.5 kg m-3) and g is acceleration due to gravity (9.81 m s-2). Units: p:[kg m-1 s-2], rhoConst:[kg m-3], g:[m s-2], H(t):[m]. Note: Quantity referred to in some contexts as hydrostatic pressure anomaly. PHIHYD is NOT corrected for global mean steric sea level changes related to density changes in the Boussinesq volume-conserving model (Greatbatch correction). m2 s-2 float 9.96921E+36 -40.362602233887 to 995.83465576172 1
RHOAnoma In-situ seawater density anomaly relative to the reference density, rhoConst. rhoConst = 1027.5 kg m-3. kg m-3 float 9.96921E+36 -27.649499893188 to 30.17712020874 1
time midpoint time of averaging period hours since 1992-01-01T12:00:00 int N/A N/A 1
time_bnds Start and end times of averaging period. N/A int N/A N/A 1
XC nonuniform grid spacing degrees_east float N/A -179.9994354248 to 179.99996948242 1
XC_bnds Bounds array follows CF conventions. XC_bnds[i,j,0] = &#039;southwest&#039; corner (j-1, i-1), XC_bnds[i,j,1] = &#039;southeast&#039; corner (j-1, i+1), XC_bnds[i,j,2] = &#039;northeast&#039; corner (j+1, i+1), XC_bnds[i,j,3] = &#039;northwest&#039; corner (j+1, i-1). Note: &#039;southwest&#039;, &#039;southeast&#039;, northwest&#039;, and &#039;northeast&#039; do not correspond to geographic orientation but are used for convenience to describe the computational grid. See MITgcm documentation for details. N/A float N/A N/A 1
YC nonuniform grid spacing degrees_north float N/A 48.678619384766 to 89.978286743164 1
YC_bnds Bounds array follows CF conventions. YC_bnds[i,j,0] = &#039;southwest&#039; corner (j-1, i-1), YC_bnds[i,j,1] = &#039;southeast&#039; corner (j-1, i+1), YC_bnds[i,j,2] = &#039;northeast&#039; corner (j+1, i+1), YC_bnds[i,j,3] = &#039;northwest&#039; corner (j+1, i-1). Note: &#039;southwest&#039;, &#039;southeast&#039;, northwest&#039;, and &#039;northeast&#039; do not correspond to geographic orientation but are used for convenience to describe the computational grid. See MITgcm documentation for details. N/A float N/A N/A 1
Z Non-uniform vertical spacing. The associated &#039;Z_bnds&#039; coordinate provides the depths of top and bottom faces of the tracer grid cell, with one pair of depths for each vertical level. m float N/A -6760.169921875 to -0.5 1
Zl First element is 0m, the depth of the top face of the uppermost tracer grid cell (i.e., the ocean surface). Last element is the depth of the top face of the deepest grid cell. The use of &#039;l&#039; in the variable name follows the MITgcm convention for naming the top face of ocean tracer grid cells. m float N/A -6520.2998046875 0 1
Zp1 Contains one element more than the number of vertical layers. First element is 0m, the depth of the top face of the uppermost grid cell. Last element is the depth of the bottom face of the deepest grid cell. m float N/A -7000.0400390625 0 1
Zu First element is -1m, the depth of the bottom face of the uppermost tracer grid cell. Last element is the depth of the bottom face of the deepest grid cell. The use of &#039;u&#039; in the variable name follows the MITgcm convention for naming the bottom face of ocean tracer grid cells. m float N/A -7000.0400390625 to -1 1
Z_bnds Provides the depths of the top and bottom faces of the tracer grid cell, with one pair of depths for each vertical level. N/A float N/A N/A 1
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