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Main Improvements and changes in v202

  • The time coverage resolution has been changed from 7 days to 1 day, meaning that the weekly averaged product is updated every day from now on.
  • We adapted the CS2SMOS processing to changes due to the update to CryoSat-2 sea ice thickness product version v2.2. 
  • We adapted the CS2SMOS processing to changes due to the update to SMOS sea ice thickness product version v3.2, which is now processed and provided by AWI.
  • An ocean mask is applied to allow for a consistent land/ocean mask throughout the entire data record in order to overcome inconsistencies due to switches of the land masks in the OSI SAF ice concentration products.
  • We now use different sea ice concentration products for the operational mode and for the reprocessing mode. In the operational mode, we use the operational OSI-401 ice concentration product, while in the reprocessing mode, the reprocessed OSI -430-b ice concentration product is used. Both are provided by OSI SAF.
  • Changes in the NetCDF variable names, fulfilling CF 1.6 conventions.

VersionDateComments
v20201.10.2019Update to version 202
v20110.01.2019Official ESA release

Product Description Overview

Parameter

Sea ice thickness

Spatial covergae

N: 90°, S:16.6°, E:180°, W:-180°

Spatial Resolution

25 km x 25 km

Temporal coverage of the data record:

November 2010 to present

Time coverage resolution

1 day

Time coverage duration7 days

Data Format(s)

NetCDF

Platforms

CryoSat-2, SMOS

Version

v202

File naming convention

NetCDF files are named using the following convention:

<convention-prefix>_<regional code>- <institution>,<platform(s)>,<grid>_<time>_<mode>_<product version>_<file version>.nc


convention-prefix

World Meteorological Organization: W

regional code

European: XX

institutionEuropean Space Agency: ESA

processing level/parameter

level 4 sea ice thickness: l4sit

Platform(s)

satellites: SMOS, CS2

grid

25 km EASE2 grid, Northern Hemisphere: NH_25KM_EASE2

time

time span: yyyymmdd - yyyymmdd

modereprocessing: r, operational: o

product version

version 2.0.2: v202

file version

version 1: 01


Example NetCDF naming for operationally processed data:

W_XX-ESA,SMOS_CS2,NH_25KM_EASE2_20190304_20190310_o_v202_01_l4sit.nc

Example NetCDF naming for reprocessed data:

W_XX-ESA,SMOS_CS2,NH_25KM_EASE2_20190304_20190310_r_v202_01_l4sit.nc

File Format

The weekly grids are given in standardized binary data format (Network common data form: NetCDF v4). Global attributes are given in Table 1. The variables are given as grid arrays, see Table 2. 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.


Table 1: Global attributes from an example NetCDF file, covering the week from March 04 to March 10, 2019.

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

202

processing_mode

r

time_of_creation

Fri Oct 11 09:04:06 2019

history

Fri Oct 11 09:04:06 2019 creation

Conventions

CF-1.6

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

2019-03-04T00:00:00Z

time_coverage_end

2019-03-11T00:00:00Z

time_coverage_duration

P7D

time_coverage_resolution

P1D

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

Variable

Description

Unit

Type

Dimension

Lambert_Azimuthal_Grid

proj4_string: +proj=laea +lon_0=0 +datum=WGS84 +ellps=WGS84 +lat_0=90.0

-

int

-

time_bnds

start and end time of the weekly retrieval

seconds since 1978-01-01 00:00:00

double

2

analysis_sea_ice_thickness

CS2SMOS weekly merged sea ice thickness

m

int

1,432,432

background_sea_ice_thickness

background field, interpolation using CS2 and SMOS sea ice thickness data

m

int

1,432,432

weighted_mean_sea_ice_thickness

weighted mean of weekly CS2 and SMOS ice thickness retrievals

m

int

1,432,432

innovation

difference between background and analysis ice thickness

m

int

1,432,432

sea_ice_concentration

sea ice concentration 

%

int

1,432,432

sea_ice_type

sea ice type 

-

int

1,432,432

correlation_length_scale

correlation length scale of background ice thickness

m

int

1,432,432

analysis_sea_ice_thickness_unc

uncertainty of the merged sea ice thickness

m

int

1,432,432

smos_sea_ice_thickness

weekly averaged SMOS ice thickness

m

int

1,432,432

cryosat_sea_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

double

1

xc

x coordinate of projection (eastings)

km

float

432

yc

y coordinate of projection (northings)

km

float

432

lon

longitude coordinate

degrees_north


float

432,432

lat

latitude coordinate

degrees_east


float

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).

Figure1: Specifications of the EASE2 25 km grid, which is used for the merged product.


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