GRAS Monitoring and Validation GRAS Team @ EUMETSAT (contact: Axel.vonEngeln@eumetsatt)

1. GRAS Monitoring and Validation GRAS Team @ EUMETSAT (contact: Axel.vonEngeln@eumetsat.int)

2. Overview • Monitoring: • performed during operational processing (basic, e.g. # of processed data segments, processor exit status, etc) • performed in parallel to dissemination (comparing orbit and bending angles) • Validation: • performed offline against other RO missions, ECMWF

3. Monitoring: Orbit • Metop orbit (left) and velocity (right) of NRT solution compared to reference one

4. Monitoring: Clock • Metop clock of NRT solution against reference solution

5. Monitoring: Bending Angles • High altitude bending angle bias (left) and noise (right) against climatology

6. Validation: ECMWF • Bending angles against co-located ECMWF data

7. Validation: COSMIC • Global bias (left) and noise (right) of GRAS and COSMIC observations

8. Validation: COSMIC • Number of co-locations (<300km, <3hours), Note: GRAS reductions on 22.12. and 18.01 are only in this data set

9. Validation: COSMIC • Bending angles against co-located COSMIC observations (<300km, <3hour)

10. Validation: Orbit Stability Issues • Upper level (60 km) biases (top) and noise (bottom) time series against ECMWF for batch POD process with COD GPS orbits and clocks (GPS week 1501 test period)

11. Validation: Orbit Stability Issues • Upper level biases at 60 km (top) and 40 km (bottom) time series against ECMWF for operational POD process with GSN orbits and clocks (operational data). Note: is within GRAS requirements.

12. Validation: Orbit Convergence Issue • Upper level biases at 40 km time series against ECMWF for operational POD process with GSN orbits and clocks (GPS week 1501 test period). Grey shaded areas indicated degraded data (about 6 % for this period)