What's New in Baseline-C for Polar Oceans

Cryo-TEMPO Baseline-C products for Polar Oceans were released in April 2024. See the product downloads page for access details.

The following evolutions have been applied in Baseline-C as compared to Baseline-B (released March 2023). Further details are provided in the Cryo-TEMPO Product Handbook and ATBD documents.

Input Data

Use of the latest evolution of ESA L1b data set as input (for all products). Only ESA CS2 Baseline-E L1b data is used as input to the CryoTEMPO processing (in CryoTEMPO Baseline-B it was necessary to use a sub-optimal mix of available data from L1b Baseline-D and Baseline-E).

Southern Hemisphere Coverage

Sea level products (sea level anomalies and dynamic ocean height) are now also produced for the southern hemisphere. In previous baselines only the northern hemisphere was covered. Southern hemisphere data is produced for all month of the year.

Region Codes

Region codes have been implemented as a parameter in the Polar Ocean product.

Polar Ocean retracker

The SAMOSA+ waveform model replaced the Threshold First Maximum Retracker Algorithm (TFMRA) from Baseline B for the Northern Hemishpere and for Baseline C for the Southern hemisphere. The SAMOSA+ retracker is better suited for waveforms with variable surface roughness. This comes at the cost of significantly higher computational load. Near real-time data is therefore still delivered with the TFMRA retracker.

Merging SAR/SARin data with LRM data

SAMOSA+ ocean retracker only works with SAR and SARin data. To complete coverage we have added ESA Baseline-C GOP data adjusted by an offset to account for possible retracker bias.

Near real-time delivery

New near real time (NRT) polar oceans data produced in Baseline-C, delivered within 18h in addition to the delivery of regular data within 31 days. See separate theme section for NRT data

LRM Data

LRM mode data is now merged from the CryoSat L2 GOPM product. In baseline-A there was no data over the areas covered by the LRM mode mask.

Retracker

A new SAMOSA+ physical retracker is used in baseline-B which replaces the empirical TFMRA retracker used in baseline-A. A reference for the SAMOSA+ retracker is provide by Laforge.A, Fleury.S, Dinardo.S, Garnier.F, Remy.F, Benveniste.J, Bouffard.J, Verley.J, Toward improved sea ice freeboard observation with SAR altimetry using the physical retracker SAMOSA+, Advances in Space Research, Volume 68, Issue 2, 2021, Pages 732-745, ISSN 0273-1177, https://doi.org/10.1016/j.asr.2020.02.001

Additional Parameters

A new region_code parameter has been included. This provided the Arctic region indentifier (0..18) for every measurement. The regions are adapted from 'A new regional mask for Arctic sea ice trends and climatologies (J. Scott Stewart and Walter N. Meier, NSIDC)'

Tide Corrections

Tide correction now uses the ARCTIDE (v1.1) tidal model where available. FES2014b is used where ARCTIDE is not available (outside it's Arctic grid area).

Further information on ARCTIDE is provided by the reference: M. Cancet, O. B. Andersen, F. Lyard, D. Cotton, and J. Benveniste, Arctide2017, a high-resolution regional tidal model in the Arctic Ocean, Advances in Space Research, vol. 62, no. 6, pp. 1324–1343, 2018, doi: 10.1016/j.asr.2018.01.007).

Atmospheric Corrections

DAC (Dynamic Atmosphere Correction) now used instead of IB (Inverted Barometer). The DAC includes the IB correction as well as a high frequency MOG2D barometric model forced by wind and pressure.

Mean Sea Surface

Mean Sea Surface (MSS) has been updated from the DTU15 to DTU21. The reference for DTU21 is Andersen, Ole Baltazar (2022): DTU21 Mean Sea Surface. Technical University of Denmark. Dataset. https://doi.org/10.11583/DTU.19383221.v1 )