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New Envisat SCIAMACHY Level 2 reprocessed dataset v6 available online

15 February 2017

The Level 2 re-processing campaign of the full Envisat-SCIAMACHY mission (from 02/08/2002 up to 08/04/2012) has been completed with the instrument processor version 6.01, using as input the SCIAMACHY Level 1b version 8 dataset.

The re-processed data (SCI_OL__2P) are made available to the user community for direct download via the ESA centralised dissemination service.

The new Level 2 data can be retrieved using the same account as used for accessing the SCIAMACHY Level 1b v8 dataset. The previous dataset (Level 2 v5.02) will remain available on the existing FTP account at the D-PAC archiving centre until dismissal on 15 March 2017 (eoa-dp.eo.esa.int).

For new users access to SCIAMACHY products can be provided through ESA Fast Registration.

Users already having access to SCIAMACHY data can retrieve the details for the accounts via the "My Online data" area (on the My Earthnet pages) using their dedicated SSO credentials.


Level 2 version 6 processor updates

SCIAMACHY Level 2 version 6.01 data includes several new products as well as significant improvements compared to the earlier version 5 data for a number of already existing products.

The following products are new in the Level 2 version 6.01 processing baseline:

  • Noctilucent clouds (NLCs) from limb measurements
  • Formaldehyde (HCHO) total column
  • Glyoxal (CHOCHO) total column
  • Methane (CH4) total column
  • NO2 Tropospheric columns from limb-nadir matching

The following already existing products are improved in version 6.01:

  • Aerosol Absorption Index (AAI), now using retrieved ozone values instead of formerly used climatology
  • Cloud fraction, introducing snow/ice separation
  • Ozone profiles retrieval extended up to 65 km using a second UV window (fall back to a single profile per state)
  • Limb cloud flagging introduced NLC detection

With the latest processing chain, the instrument degradation correction is performed during the Level 0-1b processing stage (v8) and is not applied in Level 1b-2 processing step (v6).


Level 1 version 8 input upgrades

The Level 2 version 6 dataset is processed using as input the latest Level 1b version 8 dataset, available to the users since May 2016. The processing baseline version 8 introduced several improvements in the Level 1b data. In particular for calibration aspects:

  • The stray light correction extends the matrix approach to channels 3-8
  • The memory effect correction for limb data corrects the estimate for the signal of the reset readout at new tangent heights
  • The scaling factor of the non-linearity correction for co-added data is corrected
  • The hot pixel correction for limb dark measurements is completely revised
  • The polarization correction for occultation is switched off
  • The dark calculation is now based on the selection of dark states with pixel exposure times between 0.125 and 1 second
  • The radiometric calibration uses a new physical model for the scan mirror including contamination layers
  • Key data are updated and adapted for the scan mirror model
  • The instrument degradation is corrected using the scan mirror model and via m-factor application

More information on SCIAMACHY can be found on the SPPA website.


Re-processed Level 2 dataset

The SCIAMACHY consolidated Level 2 version 6 dataset is the result of the latest ESA full-mission reprocessing campaign, completed in 2016. It brings significant improvements to the quality of the data for the new approach to compensate the instrument degradation in the spectra measured, and for the additional retrieved species.

The reprocessed dataset covers the whole operational mission lifetime period, from 2 August 2002 up to 8 April 2012.

The fields reported in the table below identify the new SCIAMACHY Level 2 version 6 products.

MPH Field Value
Processing stage flag Y
Processing centre DPA
Software version SCIA-OL/6.01

Users of SCIAMACHY Level 2 products are strongly recommended to migrate to the new reprocessed version 6 dataset.


Product format and tools

The SCIAMACHY Level 2 version 6.01 products have an updated format, available on the BEAT website. The structure of the product has been revised to enclose the new retrieved species.

The Basic Envisat Atmospheric Toolbox (BEAT) and related software have been updated accordingly, allowing fields' extraction and data handling. Latest versions of the tools are: BEAT v.6.10.1, VISAN v. 3.14 and CODA v. 2.17.3. In order to use CODA with the SCIAMACHY Level 2 version 6 data, the CODA definition file ENVISAT_SCIAMACHY-20140916.codadef specifying the new format, has to be used.


Documentation

More detailed information on all changes implemented for the reprocessing campaign with Level 2 baseline version 6 is available on the ESA Sensor Performance, Products and Algorithms portal.

  • Products Quality Readme File: ENVI-GSOP-EOGD-QD-16-0132, issue 1.1
  • Algorithm Theoretical Baseline Document (ATBD): ENV-ATB-QWG-SCIA-0085, issue 2B
  • Products Specifications Volume 15: PO-RS-MDA-GS-2009 issue 3M
  • Input / Output Data Description (IODD): ENV-IODD-DLR-SCIA-0086 issue 6


Validation

The quality of the retrieved parameters has been investigated by BIRA-IASB inspecting the SCIAMACHY full-mission dataset version 6.01. Latest results are detailed in the report:

  • Keppens et al., "Multi-TASTE Validation report – Ground-based assessment of SCIAMACHY SGP 6.01 Level-2 Data Products O3, NO2, CO, CH4, BrO and H2O", TN-BIRA-IASB-MultiTASTE-Phase-F-SCIA-SGP6-Iss1-RevB, Issue 1, Revision B, 52pp., 21 December 2016.

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