Table of Contents

This document provides a top-level overview of the GOME-2 instrument and its data processing system, from instrument build to product validation. The document is primarily aimed at those unfamiliar with GOME-2. As such the reader is provided with a high-level description of all the relevant components of the GOME-2 system with references to more detailed information in case this is required.

The GOME-2 instrument and basic operating principles are introduced in The GOME-2 instrument. A short description of the instrument hardware is provided in Instrument hardware, followed by a summary of the Data packet structure and basic instrument operation. An overview of the instrument observation modes is provided in Observation modes and the concept of GOME-2 timelines and timeline tables is introduced in GOME-2 timelines & timeline tables. In On-ground calibration & characterisation the on-ground calibration and characterisation requirements and activities are discussed. This is followed by a summary of the planned In-flight characterisation & calibration activities.

GOME-2 data processing provides an overview of the GOME-2 data processing system. The Level 0 to 1b processor, part of the Core Ground Segment (CGS) located at EUMETSAT in Darmstadt, is described in Level 0 to 1b data processing. A functional breakdown of the main components of the Level 0 to 1b data processor is given, followed by a brief description of the Algorithmic functions. Planned instrument monitoring activities are described in Sensor performance assessment, and product quality monitoring activities under Product quality evaluation. Additionally, a summary of the expected product accuracies is provided in Level 1b product summary and estimated accuracies and an overview of the Level 0, 1a and 1b product formats in Product formats & dissemination.

Level 1b to 2 data processing describes the operational Level 2 products produced under the responsibility of the Ozone Monitoring Satellite Application Facility (O3M SAF). A brief discussion of the O3M SAF consortium is given in The Ozone Monitoring Satellite Application Facility followed by a description of the Level 2 products to be produced by the O3M SAF in Operational Level 2 products from GOME-2. For each of the products the responsible institute, a brief description of the algorithm basis, and a short description of the product format are given. Examples of pre-operational products are provided if available. A summary of the range of geophysical Level 2 products and their expected accuracy and precision, both real-time and off-line, that will be generated from GOME-2 by the O3M SAF is given in Level 2 product summary and expected accuracies and precision.

In Products validation and monitoring a summary of GOME-2 in-orbit monitoring, verification and validation activities is provided. The overall objectives of in-flight GOME-2 characterisation, calibration and validation activities are listed under Objectives. GOME-2 in-orbit instrument verification, to be carried out under the responsibility of ESA/SSST, is discussed in GOME-2 in-orbit verification. Long-term instrument monitoring activities are briefly discussed in Instrument Monitoring, followed by a summary of planned Level 1 verification, confidence checking and validation activities. Atmospheric constituent verification and validation activities, to be carried out centrally at EUMETSAT in support of Level 1 validation, are discussed in Atmospheric constituent verification and validation. Level 2 operational product validation services to be provided by the O3M SAF are listed in Validation of Ozone Monitoring SAF Products, followed by a brief discussion of the role of the EUMETSAT/ESA Research Announcement of Opportunity in product calibration and validation activities in Scientific activities carried out via the EPS/MetOp RAO.

A list of acronyms is provided in Acronyms & Abbreviations. Examples of in-flight calibration parameters and their effect on the spectrum to which they are applied are provided in In-flight characterisation & calibration.

Acknowledgements

The authors wish to acknowledge the invaluable contributions of the GOME-2 project team at ESTEC, the O3M SAF project team, and colleagues at EUMETSAT without whom a successful GOME-2 flying on Metop would not be possible.