New Sentinel-3 Altimetry Processing Baseline released soon

A new Sentinel-3 Altimetry Processing Baseline is planned to be released on 9 July, introducing minor changes to the Sentinel-3 Altimetry products.

Thursday, 02 July 2020

New Sentinel-3 Altimetry Processing Baseline released soon - Improved sea ice concentrations

The changes introduced by PB_ 2.68- Marine (L1 IPF v06.18, L2 IPF v06.50), are the following:

  • New format of the L1A products: CAL1 and CAL2 do not change rapidly (respectively averaged over 10 and 27 days) and do not need to be repeated for each measurement in the Level-1A products. Thus, to provide a unique CAL1 and CAL2 per Level-1A product, the time dimension (time_l1a_echo_sar_ku) and the index (ltm_max_ind) of the following variables have been removed:
    • Gprw_meas_ku_l1a_echo_sar_ku.
    • Gprw_meas_c_l1a_echo_sar_ku.
    • Burst_power_cor_ku_l1a_echo_sar_ku.
    • Burst_phase_cor_ku_l1a_echo_sar_ku.
  • Figure 2
     
    Figure 2: Wind speed differences
    The L1 products (SR_1_SRA___, SR_1_SRA_A_, SR_1_SRA_BS) will be generated with a different chunk size at netCDF level that should significantly improve the reading speed, but has the side effect of enlarging the product size;
  • Sample file of L1A
  • Improvement of the Sea-Ice concentration close to the coastline, this will remove spuriously low values very close to the cost (circled in Figure 1, top right click to expand). The variable sea_ice_concentration_20_ku may have default values over land.
  • Improvement of the L1 AUTOCAL, the expected impact at Level-2 is low (below 0.1 dB on backscatter coefficient) but should slightly improve the wind-speed; impact on sample data is shown in Figure 2
  • Fix of an anomaly related to the computation of the filtered ionospheric correction on very small granules; the issue was only affecting NRT products and it has been corrected.
  • Figure 3
     
    Figure 3: Marine Products coverage
    Updated Marine Land Mask (SR_2_MLM_AX version 004) for the generation of the Marine products: minor changes in the geographical coverage of the Marine level-2 products, only related to the extension of the coverage from coastline to Land; from 10 km to 25 km. The extension also applies to the big inland water bodies already included in the Marine level-2 products. The geographical coverage of the Marine level-2 products remains unchanged over ocean (see Figure 3)
  • No major change at L2 Products, apart for the extension of the coverage towards the land (from 10 km to 25 km). Regarding the geophysical retrievals, a slight difference on the sigma 0 (below 0.1 dB) and wind speed (below 0.2 m/s) is observed, due to the updated L1 AUTOCAL. 
  • Documentation:

    Product Data Format Specification - SRAL and MWR Level 1 products

    Copernicus S3 Product Notice – Altimetry L1

    Sentinel-3 Product Notice – STM L2 Marine (NRT, STC and NTC)

    For more information, contact our User Service Helpdesk.

 
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