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User Requirements for GRAS SAF RO Products

User Requirements for GRAS SAF RO Products. Dave Offiler. Background. Generic (technology-free) URs for temperature & humidity profiles traceable to WMO/CBS Reviewed by APM (“Granada-1”), GRAS SAG, CLIMAP & GRAS SAF 1st User Workshop Also feedback from URs for other RO missions (WATS, ACE+)

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User Requirements for GRAS SAF RO Products

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  1. User Requirementsfor GRAS SAF RO Products Dave Offiler

  2. Background • Generic (technology-free) URs for temperature & humidity profiles traceable to WMO/CBS • Reviewed by APM (“Granada-1”), GRAS SAG, CLIMAP & GRAS SAF 1st User Workshop • Also feedback from URs for other RO missions (WATS, ACE+) • Adapted for constraints of RO technique and in particular the GRAS on Metop mission, via the EURD • URD specifies general & specific requirements on GRAS SAF data products.

  3. Main Drivers - NWP • Objective: Short to medium range weather forecasting (hours to a few days) • F/c initialisation fields optimum wrt true state of atmosphere (assimilation) • Rapid availability of global observational data • Quality control to maintain a priori expected error characteristics (Gaussian, zero bias) • Errors well characterised

  4. Main Drivers - Climate • Objective: detect & monitor long-term climate change • Long duration, continuous data sets with homogeneous, global coverage; diurnal effects unaliased • Long-term stability (no bias drift) • Accurate temperature & humidity profiles • Monthly (or annual) grid box means (Level 3) • Validation of CGMs • Initialisation of CGMs from NWP (re-)analyses

  5. Atmospheric Layers WMO Definition of Atmospheric Layers

  6. GRAS Mission Observation Requirements (NWP)

  7. GRAS Mission Observation Requirements (Climate)

  8. Products & Processing • Profiles of corrected refraction (bending angles) - Level 1b • Profiles of refractivity - Level 2a • Profiles of temperature, humidity & pressure - Level 2b • For climate, use of a consistent processing methodology (re-processing whole mission) • For NWP, availability in NRT (<3hrs)

  9. User Requirements Document • URD is a base document in the GRAS SAF documentation tree - almost all other documents flow from it. SAF operational performance will be judged against the URD • URD contains much more detail than presented here, including specific requirements, cross-referenced elsewhere • URD is stable but not fixed; can evolve in a controlled way • Real user feedback on URD (or products defined by it) are always welcome

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