Main improvements and changes in v3.3
- Transition of L1C data from v620 to v724: In v3.3, v724 L1C data is used instead of v620 L1C.
- Polar stereographic projection update: Following NSIDC we consider the EPSG 3411 and 3412 as deprecated and replaced this with 3413 and 3976 in v3.3 (https://nsidc.org/data/polar-stereo/ps_grids.html).
- NetCDF format update: Furthermore, the output of L3 data in updated to NetCDF v4.
Version | Date | Comments |
|---|---|---|
v3.2 | 15.10.2018 | Official ESA release |
| v3.3 | 03.11.2021 | Official ESA release |
Product Description
Overview
Table 1: Overview of SMOS Product
Parameter | Sea ice thickness |
Spatial covergae | Northern hemisphere, poleward of 50°N, -180°E to 180°E |
Spatial Resolution | 12.5 km x12.5 km |
Temporal Coverage: | since 15. Oct. 2010 |
Temporal Resolution | 1 day |
Data Format(s) | NetCDF v4 |
Platforms | SMOS |
Version | v3.3 |
File name
NetCDF files are named as:
SMOS_Icethickness_v3.3_north_<date>.nc
File Format
Daily mean SMOS sea ice thickness is given in NetCDF v4 format. Global attributes are given in Table 2. The variables are given as grid arrays as listed in Table 3.
Table 2: Global attributes from an example NetCDF file.
Attribute | Value |
title | Daily gridded sea-ice thickness and auxiliary parameters from satellite L-band radiometry data |
project | CS2SMOS PDS CR-1: SMOS Sea Ice Data Product Processing and Dissemination Tasks, supported by ESA |
institution | Alfred-Wegener-Institut Helmholtz Zentrum für Polar und Meeresforschung (AWI), http://www.awi.de |
contributor_name | Xiangshan Tian-Kunze, Lars Kaleschke, Stefan Hendricks |
publisher_email | |
platform | “ESA Soil Moisture and Ocean Salinity (SMOS) mission” |
sensor | “Microwave Imaging Radiometer using Aperture Synthesis (MIRAS)” |
source | SMOS v724 L1C brightness temperature |
product_version | v3.3 |
Processing level | L3c |
grid | NSIDC polar stereographic projection. https://nsidc.org/data/polar-stereo/ps_grids.html |
tracking id | 08533af0-7656-4f35-b0a8-7ae4081a2c9a |
naming authority | de.awi |
history | Product generated with SMOS sea ice thickness retrieval Algorithm v3.3 |
summary | This dataset contains Level-3 daily sea ice thickness products from satellite observations in the northern hemisphere. Northern hemisphere sea ice thickness coverage is limited to the winter month between October and April. 100% sea ice coverage is assumed, which leads to underestimation of sea ice thickness. |
topiccategory | Oceans Climatology Meteorology Atmosphere |
keywords | Earth Science > Cryosphere > Sea Ice > Ice Depth/Thickness, Earth Science > Oceans > Sea Ice > Ice Depth/Thickness, Earth Science > Climate Indicators > Cryospheric Indicators > Ice Depth/Thickness, Geographic Region > Northern Hemisphere, Vertical Location > Sea Surface, Institutions > AWI > Alfred Wegener Institute for Polar and Marine Research |
id | awi-cs2smos-l3c-sithick-smos-nh_12p5_km_polstereo-YYMMDD-fv3p3 |
doi | none |
Date_created | e.g. “Tue Mar 24 17:37:59 2020” |
spatial_resolution | 12.5 km grid spacing |
time_coverage_duration | P1D |
time_coverage_start | yyyy-mm-ddT00:00:00 |
time_coverage_end | yyyy-mm-ddT23:59:59 |
time_coverage_resolution | P1D |
geospatial_bounds_crs | EPSG:3413 |
geospatial_lat_max | 90.0 |
geospatial_lat_min | 50.0 |
geospatial_lon_max | 180.0 |
geospatial_lon_min | -180.0 |
geospatial_vertical_max | 0.0 |
geospatial_vertical_min | 0.0 |
references | 1) Kaleschke, L., X. Tian-Kunze, N. Maass, M. Maekynen, and M. Drusch (2012), Sea ice thickness retrieval from SMOS brightness temperatures during the Arctic freeze-up period, Geophys. Res. Lett., 39, L05501, doi:10.1029/2012GL050916. (2) Tian-Kunze, X., Kaleschke, L., Maass, N., Maekynen, M., Serra, N., Drusch, M., and Krumpen, T., SMOS-derived sea ice thickness: algorithm baseline, product specifications and initial verification, The Cryosphere, 8, 997-1018, doi:10.5194/tc-8-997-2014, 2014 (3) Kaleschke, L., Tian-Kunze, X., Maass, N., Beitsch, A., Wernecke, A., Miernecki, M. and others, SMOS sea ice product: operational application and validation in the Barents Sea marginal ice zone, Remote Sensing of Environment 180 (2016), 264-273. doi: 10.1016/j.rse.2016.03.009 (4) Tietsche, S., Alonso-Balmaseda, M., Rosnay, P., Zuo, H., Tian-Kunze, X., and Kaleschke, L.: Thin Arctic sea ice in L-band observations and an ocean reanalysis, The Cryosphere, 12, 2051-2072, https://doi.org/10.5194/tc-12-2051-2018, 2018. |
Table 3: NetCDF file content.
| Variable | Description | Unit | Type | Dimension |
|---|---|---|---|---|
| latitude | latitude coordinate | degrees_north | float32 | 896 x 608 |
| longitude | longitude coordinate | degrees_east | float32 | 896 x 608 |
x | Projection_x_corordinate | km | float32 | 608 |
| y | Projection_y_corordinate | km | float32 | 896 |
| sea_ice_thickness | SMOS sea ice thickness | m | float32 | 1 x 896 x 608 |
| ice_thickness_uncertainty | sea ice thickness total uncertainty | m | float32 | 1 x 896 x 608 |
| saturation_ratio | ratio of retrieved ice thickness and maximal retrievable ice thickness | % | int16 | 1 x 896 x 608 |
| TB | brightness temperature intensity (TBh+TBv)/2 | K | float32 | 1 x 896 x 608 |
| TB_uncertainty | brightness temperature uncertainty defined as one standard deviation of TB devided by the sqrt(nPair) | K | float32 | 1 x 896 x 608 |
| Tsurf | SMOS derived snow surface temperature | K | float32 | 1 x 896 x 608 |
| Sice | Bulk ice salinity | psu | float32 | 1 x 896 x 608 |
| nPair | number of TBh and TBv pairs available | int16 | 1 x 896 x 608 | |
| RFI_ratio | percent of RFI-contaminated measurements in total measurements | % | float32 | 1 x 896 x 608 |
| land | land_binary_mask | int8 | 896 x 608 | |
| time | hours since 2010-01-01 00:00:00 | hour | double | 1 |
Grid
Table 4: Northern Hemisphere Grid Coordinates of NSIDC Polar Stereographic Grids
(ref.: https://nsidc.org/data/polar-stereo/ps_grids.html)
X (km) | Y (km) | Latitude (deg) | Longitude (deg) | position |
-3850 | 5850 | 30.98 | 168.35 | corner |
0 | 5850 | 39.43 | 135.00 | midpoint |
3750 | 5850 | 31.37 | 102.34 | corner |
3750 | 0 | 56.35 | 45.00 | midpoint |
3750 | -5350 | 34.35 | 350.03 | corner |
0 | -5350 | 43.28 | 315.00 | midpoint |
-3850 | -5350 | 33.92 | 279.26 | corner |
-3850 | 0 | 55.50 | 225.00 | midpoint |
