1. Assimilation and Evaluation of MISR Cloud Tracked Winds with GEOS-5 Operational Data Assimilation System Junjie Liu 1 and Kevin Mueller 1 1. Jet Propulsion Lab (JPL), Caltech With special thanks to Joe Stassi (GMAO), Dan Holdaway (GMAO), Meta Sienkiewicz (GMAO), Will McCarty (GMAO), Ron Gelaro (GMAO), Nancy Baker (NRL), David Diner (JPL), and Earl Hansen (JPL) ©2015. California Institute of Technology. Government sponsorship acknowledged.

2. Outline Brief description of current winds in GEOS-5, MISR, motivation and objective. GEOS5 assimilation experiments Results Summary, and ongoing work and future plans

3. Current wind observation coverage still have large gaps plot courtesy of Dr. Dagmar Merkova AMVs assimilated at 00Z20 August, 2010 Sparse observation coverage over the mid latitudes in each Hemisphere. Low density wind observations over low levels.

4. The Multi-Angle Imaging SpectroRadiometer (MISR) retrieves along-track and cross-track winds 4 Along-track Cross-track Up ∆t ~ 7 minutes Cross-track Along-track MISR wind coverage within 6 hours

5. MISR retrieves cloud height along with winds Height and motion retrieved in single 7 minute satellite overpass Height measured through parallax Along-track motion differentiated from parallax using 3 rd camera Sensitive to camera pointing and correspondence accuracy Yields correlated error between retrieved height and along-track motion 5 Two angles allow for geometric retrieval of feature height based on pattern matching MISR imagery (below) Feature height and motion are retrieved using triplets of MISR cameras

6. Motivation and Objective MISR winds has been shown to have positive impact on the forecast error reduction in NAVEM  Optimally assimilate and evaluate the impact of MISR winds on GEOS-5 operational data assimilation system Plots courtesy of Dr. Nancy Baker (NRL) MISR winds Per observation impact (10 -6 J/kg) Percent reduction per observation type 0.7 6.9

7. GEOS-5 assimilation experiments GEOS-5 AGCM + GSI analysis (~0.5°, L72) Time period: Dec 16, 2009 – Feb 16, 2010 Data thinning on 200km×100hPa box Observation errors: 3.0 m/s Quality control: o-f<20 m/s Assimilate u and v components Observation impact on 24-hour forecast error reduction: moist energy norm, calculate every 6 hours

8. MISR winds has reduced 24-hour forecast errors in GEOS-5 DAS ~3000 MISR observations assimilated in each 6-hour assimilation cycle. Per observation impact is the 4 th largest among all observation types. The MISR total impact is 0.7% of the impact from all obs. 3.11e- 6 0.7% Observation count by classPer obs impact by class Percent total obs impact by class Satwind MISR Dropsond WindSat MISR

9. Comparison to the MISR wind impact in NAVGEM Per observation impact of MISR winds on GEOS-5 is smaller than in NAVGEM Percent total obs impact is the same as in NAVGEM. Per obs impact on GEOS-5 Per obs impact on NAVGEM 3.1e-6 6.9e-6 0.7% Percent impact on NAVGEM Percent total obs impact on GEOS-5 0.7% Note: NAVGEM for Hurricane Sandy case Courtesy of Dr. N. Baker

10. Largest positive impact on the SH mid latitudes MISR have largest number of observations around 900 hPa. Largest positive impact over the SH mid latitudes. Negative impact ~45° in each hemisphere.

11. MISR wind impact vs. other wind impact The observation coverage over the SH mid latitudes is sparse in control GEOS-5; MISR wind observation coverage complements the current default wind observation coverage in GEOS-5. All wind impact (not including MISR)All wind # (not including MISR) MISR wind impact MISR # SH NH

12. The Multi-Angle Imaging SpectroRadiometer (MISR) retrieves along-track and cross-track winds 12 Along-track Cross-track Up ∆t ~ 7 minutes Cross-track Along-track MISR wind coverage within 6 hours

13. MISR u-component MISR v-component U-component has much larger impact on improving the 24-hour forecast Per obs innovation -9090 Obs # Total impact U-component has largest positive impact in lower levels; v-component has largest positive impact in higher levels.

14. Detecting the bad orbits with observation impact calculation and O-F statistics Observation impact calculation shows large negative impact from certain orbits; may have georegistration errors. Removing the orbits have improved the results. MISR wind impact Dec 16, 2009 – Jan 15, 2010 Mean O-F for v-component

15. Summary MISR is expected to operate till 2020+. MISR retrieves height along with winds. Cross-track wind is more accurate than along- track winds MISR wind observation coverage complements the current winds assimilated in GEOS-5. Assimilating MISR winds has improved the 24-hour forecast accuracy. The per obs impact of MISR is the 4 th largest among all observation types. The per obs MISR wind impact in GEOS-5 is smaller than the per- obs MISR wind impact in NAVGEM. However, the percent total MISR wind impact is 0.7%, the same as in NAVGEM. The u-component has much larger positive impact on the forecast error reduction than the v-component.

16. Ongoing work and future plans Developing observation operator that can assimilates cross-track and along-track winds Optimize MISR wind quality control method Assess MISR wind impact on hurricane Sandy forecast Test the MISR wind impact with different baseline observations (e.g., obs assimilated in NAVGEM) in GEOS-5. Transition from O2R to R2O