onboard of Metop-A COSMIC Workshop 2009 Boulder, USA

Transcription

1 GRAS Radio Occultation Measurements onboard of Metop-A A. von Engeln 1, Y. Andres 1, C. Cardinali 2, S. Healy 2,3, K. Lauritsen 3, C. Marquardt 1, F. Sancho 1, S. Syndergaard EUMETSAT, ECMWF, GRAS SAF Contact: Axel.vonEngeln@eumetsat.int COSMIC Workshop 2009 Boulder, USA

2 Overview EUMETSAT / SAF Network Radio Occultation (RO) Introduction GRAS Data Analysis Recent ECMWF Results Recent GRAS SAF Results Conclusion/Next Steps COSMIC Workshop 2009 Boulder, USA Slide: 2

3 EUMETSAT What we do EUMETSAT is the European operational satellite agency for monitoring weather, climate, & environment. For this we operate a system of meteorological satellites to deliver weather and climate related satellite data 24/7. Member and cooperating states COSMIC Workshop 2009 Boulder, USA Slide: 3

4 SAF Network Member State 1 Cooperating State Support to Nowcasting and Very Short Range Forecasting Objectives of the SAF Network Ocean and Sea Ice Climate Monitoring Numerical Weather Prediction Land Surface Analysis Ozone and Atmospheric Chemistry Monitoring 6 Improve the ability of EUMETSAT s Member States to exploit satellite data; Encourage the utilisation of existing skills and infrastructure in Member States and Cooperating States; 7 8 GRAS Meteorology Support to Operational Hydrology and Water Management SAF Consortium Member Additional Met Service Users Facilitate cost-effective exploitation by ensuring that services are distributed in the most appropriate way; Foster development of cooperation with non-member States and other organisations. COSMIC Workshop 2009 Boulder, USA Slide: 4

5 Introduction: RO Principle GRAS Radio Occultation instrument observing GPS satellites: - 2 rising, i 2 setting (atmosphere) - 8 zenith (orbit) observations: - about 650 profiles / day - 0.2km 1km vertical resolution level l 1b products (EUMETSAT): - bending angle (2h 15 min) Radio Occultation Principle: Observation of e.g. GPS satellite signals through the atmosphere; changing refractivity leads to bending of rays level 2 products (GRAS SAF): - refractivity (3h, pre-operational) - T, WV (3h, ~ mid-2010) - climate applications (~ 2010) 0) COSMIC Workshop 2009 Boulder, USA Slide: 5

6 GRAS Data: Latency & # of Occultations Recent GRAS data latency # of Occultations GRAS, COSMIC (6 sat.), and co-locations ( 300km, 3h) COSMIC Workshop 2009 Boulder, USA Slide: 6

7 GRAS Data: Measurement Noise Noise histogram of GRAS and COSMIC measurements vs. ECMWF around 60km, std dev and number of occ/day given in brackets COSMIC Workshop 2009 Boulder, USA Slide: 7

8 GRAS Data: Quality After Prior COSMIC Update GRAS bending angles compared to ECMWF forecast fields before / after GRAS co-located to COSMIC data (9 ECMWF update on 10 th of March 2009 (grey box indicates current GRAS processing limitation) days, 300km, 3h) before / after UCAR update on 12 th of October 2009 COSMIC Workshop 2009 Boulder, USA Slide: 8 (grey box indicates current GRAS processing limitation)

9 Recent ECMWF Results Sean Healy, Carla Cardinali

10 Experiments with Modified COSMIC data Statistics for Dec 08 (NH) COSMIC-4 COSMIC-6 GRAS Left: Good agreement between GRAS and COSMIC now; Right: aircraft temp measurements black listed (know to be biased)

11 Impact Trials comparing COSMIC / GRAS-only ECMWF 100 hpa bias (top) and std dev (bottom) improvements over no RO data of COSMIC only (solid), GRAS only (dotted) for different latitude bands.

12 Forecast Error Sensitivity to Observation Information Content (%) GPS RO Observations (~2.6% of obs) 90% are radiances obs Impact of radio occultation ti over Impact of different observing altitude systems on ECMWF 24h forecasts

13 Kent Lauritsen, Stig Syndergaard 13

14 Status of GRAS SAF data products NRT Profiles - Refractivity pre-operational since March 2009; upgrade to full operational version approved by SG and planned for Oct/Nov 2009; - Data disseminated over GTS and EUMETCast (as BUFR files); - open for archived NRT data; - 1DVar T and q profile products in the pipeline: generation of pre-operational version planned after the refractivity upgrade; Offline Profiles - Offline profiles to be generated when offline data based on GRAS raw sampling data are available from EUMETSAT (expected first half 2010); - Validated profiles expected to be available on in the second half of 2010; Climate Data - Data consisting of e.g. gridded monthly zonal means of bending angle, refractivity, temperature, humidity, and geopotential height; - Prototype products based on NRT GRAS data generated continuously; - Validated data planned for approval by SG in the fall of 2010; 14

15 GRAS SAF ROPP software package ROPP software package - ROPP-3: released in July 2009 (contains wave optics processing modules); - ROPP-4: release planned for Dec 2009 (will contain 2D bending angle forward model); Currently 95 users of ROPP Available for download on: Supporting Mark Ringer in work related to getting some of the ROPP observation operators integrated into the CFMIP observational simulator package (COSP) that is used at many places within the climate community. 15

16 Planned improvement in refractivity statistics Current version is based on statistical ti ti optimization i using a background obtained from local MSIS and 1-parameter fit; Planned full operational version is based on a combination of MSIS, a global search, and a 2-parameter fit; 16

17 GRAS SAF Climate data prototype climate data based on GRAS NRT Zonal monthly mean bending angle for Aug-Oct Generated from EUM bending angles. 17

18 GRAS SAF Climate data prototype climate data based on GRAS NRT Zonal monthly mean bending angle for Aug-Oct Generated from EUM bending angles. 18

19 Conclusions GRAS instrument working very well data shows good agreement with ECMWF /COSMIC data quality better than COSMIC at high h altitudes EUMETSAT & GRAS SAF provide data from L0 to L3 Radio Occultation shows large impact in NWP and has great potential for climate observations continues to reveal deficiencies in NWP assimilation COSMIC Workshop 2009 Boulder, USA Slide: 19

20 GRAS Ongoing and Next Steps Ongoing: wave optics processing (raw sampling, nav. bits) improvements to orbit processing cycle slip removal processing impact study on structural uncertainty RO trend study using bending angles Next Steps: day 2 products quality control based on 1DVar reprocessing of entire data set COSMIC Workshop 2009 Boulder, USA Slide: 20