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Version	Date	Comments
v2.0	15.10.2018	Official ESA release

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Product Description

Overview

Parameter	Sea ice thickness
Spatial covergae

NetCDF file naming

N: 90°, S:16.6°, E:180°, W:-180°
Spatial Resolution	25 km x 25 km
Temporal Coverage:	November 2010 to present
Temporal Resolution	7 days
Data Format(s)	NetCDF
Platforms	CryoSat-2, SMOS
Version	v2.0

File naming convention

NetCDF files are named using the following convention:

<institution>-<product>-<processing level>-<parameter>-<platform(s)>-<mode>-<grid>-<time>-<version>.nc

Institution	Alfred Wegener Institute (AWI): awi
product	CryoSat-2/SMOS merged product: cs2smos
processing level	Level 4: l4
parameter	Sea ice thickness: sithick
Platform(s)	Satellites: SMOS, CryoSat-2
mode	Reprocessing: rep, near-real-time: nrt
grid	25 km EASE2 grid, Northern Hemisphere: nh25km_ease2
time	Time span: yyyymmdd - yyyymmdd
version	Version 2.0: fv2p0

Example NetCDF naming for

NetCDF files of

near-real time processed data

are named

:

awi-cs2smos-l4-sithick-cryosat2_smos_merged-

nrt

rep-

nh_25km

nh25km_ease2-

yyyymmdd

20180326_

yyyymmdd

20180401-fv2p0.nc

Example NetCDF

files of

naming for reprocessed data

are named

:

awi-cs2smos-l4-sithick-cryosat2_smos_merged-rep-

nh_25km

nh25km_ease2-

yyyymmdd

20180326_

yyyymmdd

20180401-fv2p0.nc

Description of NetCDF data files

File Format

The weekly

analysis

grids are given in standardized binary data format (Network common data form: NetCDF v4). Global attributes are given in Table 2. The variables are given as grid arrays, see

therefore Table 1. All grids are projected onto the 25 km EASE2 Grid, which is based on a polar aspect spherical Lambert azimuthal equal-area projection (Figure 1)

, therefore Table 3. NetCDF files are formatted according to CF conventions: CF-1.6 ACDD-1.3. We use a scaling factor of 10^-3 and a fillvalue = -2147483647.

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Table 2: Global attributes from an example NetCDF file, covering the week from March 26 to April 01, 2018.

Attribute	Value
title	Sea Ice Thickness derived from merging CryoSat-2 and SMOS ice thickness
description	Weekly Arctic sea-ice thickness derived from CryoSat-2 and SMOS using an optimal interpolation scheme
summary	Weekly Arctic sea-ice thickness derived from CryoSat-2 and SMOS using an optimal interpolation scheme
keywords	Cryosphere > Sea Ice > Sea Ice Thickness
product_version	fv2p0
processing_mode	rep
time_of_creation	Mon Oct 22 17:27:55 2018
history	Mon Oct 22 17:27:55 2018 creation
Conventions	CF-1.6 ACDD-1.3
spatial_resolution	25.0 km grid spacing
geospatial_lat_min	16.623929977416992
geospatial_lat_max	90.0
geospatial_lon_min	-180.0
geospatial_lon_max	180.0
geospatial_vertical_min	0.0
geospatial_vertical_max	0.0
time_coverage_start	2018-03-26T00:00:00Z
time_coverage_end	2018-04-01T00:00:00Z
time_coverage_duration	P7D
time_coverage_resolution	P7D
platform	CryoSat-2, SMOS
project	CS2SMOS PDS: SMOS & CryoSat-2 Sea Ice Data Product Processing and Dissemination Service
institution	Alfred-Wegener-Institut Helmholtz Zentrum für Polar und Meeresforschung (AWI), http://www.awi.de
creator_name	Alfred-Wegener-Institut Helmholtz Zentrum für Polar und Meeresforschung (AWI), http://www.awi.de
creator_type	institution
creator_url	https://spaces.awi.de/confluence/x/DwVmEQ
publisher_email	robert.ricker@awi.de
references	Ricker, R., Hendricks, S., Kaleschke, L., Tian-Kunze, X., King, J., and Haas, C.: A weekly Arctic sea-ice thickness data record from merged CryoSat-2 and SMOS satellite data, The Cryosphere, 11, 1607-1623, https://doi.org/10.5194/tc-11-1607-2017, 2017.
_CoordSysBuilder	ucar.nc2.dataset.conv.CF1Convention

Table 3: NetCDF file content. Note, that we use a scaling factor of 10^-3 and a fillvalue = -2147483647

Figure 1: Specifications of the EASE2 25 km grid, which is used for the merged product

.

Variable	Description	Unit	Type	Dimension
Lambert_Azimuthal_Grid

-

Add description	-	int	-
time_bnds

-

Start and end time of the weekly retrieval	seconds since 1978-01-01 00:00:00	int	2
analysis_ice_thickness	CS2SMOS weekly merged sea ice thickness	m	Int	1,432,432
background_ice_thickness

optimal interpolation

background field, interpolation using CS2 and SMOS sea ice thickness data	m	Int	1,432,432
weighted_mean_ice_thickness	weighted mean of weekly

cs2

CS2 and

smos

SMOS ice thickness retrievals	m	Int	1,432,432
innovation	difference between background and analysis ice thickness	m	Int	1,432,432
ice_conc	sea ice concentration	%	Int	1,432,432
ice_type	sea ice type (OSI-403-c)	-	Int	1,432,432
correlation_length_scale	correlation length scale of

sea

background ice thickness	m	Int	1,432,432
analysis_thickness_unc	uncertainty of the merged sea ice thickness	m	Int	1,432,432
smos_ice_thickness	weekly averaged SMOS ice thickness	m	Int	1,432,432
cs2_ice_thickness	weekly averaged CryoSat-2 ice thickness	m	Int	1,432,432
time	reference time of product (middle of the week)	seconds since 1978-01-01 00:00:00	Int	1
xc	x coordinate of projection (eastings)	km	Int	432
yc	y coordinate of projection (northings)	km	Int	432
lon	longitude coordinate	degrees_north	Int	432,432
lat	latitude coordinate	degrees_east	int	432,432

Grid

All grids are projected onto the 25 km EASE2 Grid, which is based on a polar aspect spherical Lambert azimuthal equal-area projection (Brodzik et al., 2012). The grid dimension is 5400 km x 5400 km, equal to a 432 x 432 grid. The grid is centered on the geographic Pole, meaning that the Pole is located at the intersection of center cells (Figure 1).

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