Global Sea Ice (GIOMAS) Data Sets

GIOMAS (Globle Ice-Ocean Modeling and Assimilation System) Data:

The GIOMAS Data and some supporting programs can be grabbed here. The global sea ice thickness fields are illustrated by movies.


VariableVariable nameDimensionUnitFile name
Sea ice thicknessheff2-Dmheff.H<yyyy>
Sea ice concentrationarea2-Dfractionarea.H<yyyy>
Sea ice velocity u and vicevel2-Dm/sicevel.H<yyyy>
Sea ice growth rate *iceprod2-Dm/siceprod.H<yyyy>
Sea ice melt tendency due to ocean heat flux **oflux_ocn2-Dm/soflux_ocn.H<yyyy>
Snow depth (water equivalent) ***snow2-Dmsnow.H<yyyy>
Ocean surface temperature (at 2.5 m)otemp12-DCotemp1.H<yyyy>
Ocean surface salinity (at 2.5 m)osali12-Dpsuosali1.H<yyyy>
Ocean surface velocity u and v (at 2.5 m)ouv12-Dcm/souv1.H<yyyy>

* Ice growth rate is the net ice production due to atmospheric heating/cooling and oceanic heat flux.
** When converted to W/m*m by multiplying a negative value of (-3.02*10**8), this variable becomes ocean heat flux to the mixed layer and can be used to drive global sea ice models.
*** To convert to actual snow depth, multiply a factor of (water density/snow density).

Methods and data:

SSM/I ice concentration data were assimilated in the TED sea ice model that is used in GIOMAS.


Grid Parameters:

Grid configurationGeneralized curvilinear coordinate system
Grid Size:360 x 276
Spatial CoverageGlobal. The grid domain is shown here
lon and lat for scalar fieldsgrid.dat
lon and lat for vector fieldsgrid.dat.pop
angle between latitude line and  grid cell x-coordinate linealpha.fortran.dat


Temporal Coverage:

Currently monthly data  from 1/1979 to the present. Each file contains 12 monthly 2-D fields. For sea ice and ocean velocities, first comes 2-D u component followed by v component.

Data Format:

The data are flat binary files (no headers) consisting of single-precision floating-point numbers. The data were written as unformatted direct access files on a Linux PC cluster. Byte order may have to be changed if you are using a machine using a different byte order (e.g. HP workstations ). A FORTRAN program demonstrating how to read sea ice thickness and grid information is provided (read_hi_uice.f). An IDL program demonstrating how to read (and plot) scalar fields and grid information is also provided ( Another IDL routine ( is provided to read  vector fields and vector grid information. It also plots ice velocity on a spherical coordinate system using the angle between the latitude line and  the grid cell x-coordinate line (alpha.fortran.dat). The structure of the data sets should be apparent from these routines. Please let us know if  you have difficulty reading the data.


read_hi_uice.f  : FORTRAN program  to read sea ice thickness and grid information, can be used to read other scalar fields : IDL program to read and plot sea ice thickness, can be used to read other scalar fields such as ice concentration and ice growth : IDL program to read and plot sea ice velocity, can be used to read and plot other vector fields such as ocean velocity IDL routine for drawing color bar  IDL routine for setting colors IDL routine for plotting vectors IDL routine for plotting vectors  IDL routine for plotting vectors  IDL routine for plotting vectors  IDL routine for plotting vectors
io.dat_360_276.output: model grid mask; ocean levels > 0, land = 0

Other Ways for Data Access:

You can access the data via FTP by entering ‘ftp’, then ‘anonymous’ as your log name, and your email address as password. After entering the web site, go to zhang/Global_seaice.
You can also access the data from here:
If you are downloading the data, please e-mail us at zhang©apl•washington•edu  (zhang©apl•washington•edu)   we can update you on changes, bugs etc.

Other Related (Arctic Sea Ice-Ocean) Data Sets:


We’d appreciate your reference to the following paper for using the data:

Zhang, Jinlun and D.A. Rothrock: Modeling global sea ice with a thickness and enthalpy distribution model in generalized curvilinear coordinates, Mon. Wea. Rev. 131(5), 681-697, 2003.