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Main Improvements and changes in v203

  • We adapted the CS2SMOS processing to changes due to the update to CryoSat-2 sea ice thickness product version v2.3. 

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

v203

07.10.2019Update to version 203

v202

01.10.2019Update 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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