data

Variability and Trends in Antarctic Sea Ice

Funded by NSF Antarctic Program

Jinlun Zhang
University of Washington

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Introduction

Model

Data

Source Code

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GIOMAS Data: (under construction)

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

Variables:

Variable	Variable name	Dimension	Unit	File name
Sea ice thickness	heff	2-D	m	heff.H<yyyy>
Sea ice concentration	area	2-D	fraction	area.H<yyyy>
Sea ice velocity	icevel	2-D	m/s	icevel.H<yyyy>
Sea ice growth rate *	icegrow	2-D	m/s	icegrow.H<yyyy>
Sea ice melt due to ocean heat flux	melt	2-D	m/s	melt.H<yyyy>
Snow depth (water equivalent) **	snow	2-D	m	snow.H<yyyy>

* Ice growth rate is due to atmospheric heating/cooling, which represents ice growth/decay in ice covered areas and heat loss/gain in open water areas; use ice thickness or concentration fields to determine ice covered areas. ** 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:

Grid Parameters:

Grid configuration	Generalized curvilinear coordinate system
Grid Size:	360 x 276
Spatial Coverage	Global. The grid domain is shown here
lon and lat for scalar fields	grid.dat
lon and lat for vector fields	grid.dat.pop
angle between latitude line and grid cell x-coordinate line	alpha.fortran.dat

Temporal Coverage:

Currently monthly data from 1/1970 to 12/2005. Each file contains 12 monthly 2-D fields.

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 (read_draw_hi.pro). Another IDL routine (read_draw_uice.pro) 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.

Utilities:

read_hi_uice.f : FORTRAN program to read sea ice thickness and grid information, can be used to read other scalar fields
read_draw_hi.pro : IDL program to read and plot sea ice thickness, can be used to read other scalar fields such as ice concentration and ice growth
read_draw_uice.pro : IDL program to read and plot sea ice velocity, can be used to read and plot other vector fields such as ocean velocity
colorbar.pro: IDL routine for drawing color bar
con_clr.pro: IDL routine for setting colors
LLtoXY.pro: IDL routine for plotting vectors
LLtoXY_s.pro: IDL routine for plotting vectors
XYtoLL.pro: IDL routine for plotting vectors
XYtoLL_s.pro: IDL routine for plotting vectors
heads.pro: IDL routine for plotting vectors
levels_25_t_360_276: model grid mask; ocean levels > 0, land < 0

Other Ways for Data Access:

You can access the data via FTP by entering 'ftp psc.apl.washington.edu', 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: ftp://psc.apl.washington.edu/zhang/Global_seaice
If you are downloading the data, please e-mail us at zhang@apl.washington.edu we can update you on changes, bugs etc.

Attribution:

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.

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