Improvement of Dynamic Balance for a LAPS/STMAS HotstartAnalysis for Short-range Forecast

1. Improvement of Dynamic Balance for a LAPS/STMAS HotstartAnalysis for Short-range Forecast Yuanfu Xie, Steve Albers, Hongli Jiang Paul Schultz and ZoltanToth Forecast Applications Branch GSD/ESRL/NOAA Workshop on Use of NWP for Nowcasting, Oct. 24-26, 2011

2. Outline Workshop on Use of NWP for Nowcasting, Oct. 24-26, 2011 Overview of LAPS/STMAS hotstart analyses; Applications; Issues with balance of hot-started fields; Approaches for resolving these issues; Numerical experiments; Conclusions.

3. LAPS and STMAS Workshop on Use of NWP for Nowcasting, Oct. 24-26, 2011 • Local Analysis and Prediction System (LAPS): • Objective analysis with variational components on humidity and satellite data assimilation; • Multiscale analysis but hot start and balance as post processes; • Space and Time Multiscale Analysis System (STMAS): • A sequential variational analysis (3-4DVAR) based on a multigrid technique; • Natural variational extension of 3-4DVAR and objective analysis; • Its variational hot-start is under development while it borrows LAPS hot-start process for now.

4. A multigrid approach Long waves Short waves Sequence of 3-4DVARs with proper balances Similar to LAPS analysis with less requirement of covariance Standard 3-4DVAR With a band covariance Reference: A Space–Time Multiscale Analysis System: A Sequential Variational Analysis Approach Y. Xie, S. Koch, J. McGinley, S. Albers, P. E. Bieringer, M. Wolfson, M. Chan, Monthly Weather Review Volume 139, Issue 4 (April 2011) pp. 1224-1240 Possible ensemble Filter application

5. Relation between STMAS and LAPS Insitu, Radar, satellite, cloud analysis Balance and constraints In one variational analysis Ultimately Forecast STMAS Temporarily Wind analysis Temp/Height analysis Humidity analysis Cloud analysis balance LAPS

6. Cloud Analysis Flow Chart Cloud Fraction 3-D Isosurface

7. FH FL LAPS HOT START INITIALIZATION Three-Dimensional Cloud Analysis METAR + FIRST GUESS

8. Hot-start components Workshop on Use of NWP for Nowcasting, Oct. 24-26, 2011 Vertical velocity/horizontal divergence; Temperature/height adjustment; Hydrometeor assimilation; Consistent water vapor fields. LAPS Hot-started analysis and forecast are operational at US WFOs. LAPS is very portable; Many version of LAPS hot-start analyses are running at different places, K-LAPS (KMA), T-LAPS (US terminal LAPS), O-LAPS (related to CAPS) and so on, through close collaborations.

9. FH FL STMAS HOT START INITIALIZATION Minimization of STMAS variational cost function Subject to dynamic constraints and appropriate forward models NWP METAR + FIRST GUESS

10. Cloud / Reflectivity / Precip Type (1km analysis) Obstructions to visibility along approach paths DIA

11. Hot-start impact 6-hr Diabatically (LAPS) initialized WRF-ARW forecast Analysis

12. Applications A hot-started LAPS/STMAS is good for severe weather applications, such as warn-on-forecast, convective initiation, storm boundary detection and etc. CRITICAL for 0-3 forecast. • MIT/LL storm detection since 2004 for FAA applications; • US regional and local WFOs; • Central Weather Bureau, Taiwan; • National Marine Data & Information Service, China; • Early collaboration with MIT for 40+ US airports (T-LAPS); • …… • More than 150 users over the world. Workshop on Use of NWP for Nowcasting, Oct. 24-26, 2011

13. STMAS used as a Nowcasting Tool FAA CoSPA Application: Over CONUS At 2km resolution 15 minute analysis cycle in real time Workshop on Use of NWP for Nowcasting, Oct. 24-26, 2011

14. Issues: Fast Decrease of Good Analysis ETS (20 dBz) 30-day statistics ending Oct. 21, 2011 Workshop on Use of NWP for Nowcasting, Oct. 24-26, 2011

15. Issues with balance of hot-start We observed fast ETS score decreasing of our hot-started forecasts and investigated for further improvements. Workshop on Use of NWP for Nowcasting, Oct. 24-26, 2011

16. Issues with balance of hot-start • High frequency noise is not good for supporting the precipitating liquid; • Cloud omega (vertical velocity) contains sharp gradients; Solutions: • A better solver of the balance: a reduced 2D solver for temporary solution; a multigrid full 3D solver will be implemented for STMAS; • Smooth cloud omega is imposed in the current hot-start scheme for both LAPS and STMAS varying more consistently with reflectivity. Workshop on Use of NWP for Nowcasting, Oct. 24-26, 2011

17. Forecast at 2011-09-04 00Z Bias ETS Change hot-start cloud omega Add a reduced 2d solver

18. STMAS with a reduced 2D solver Workshop on Use of NWP for Nowcasting, Oct. 24-26, 2011

19. STMAS with a reduced 2d solver Workshop on Use of NWP for Nowcasting, Oct. 24-26, 2011

20. Conclusions • STMAS surface has been an important nowscasting tool for FAA storm boundary detection (CoSPA); • LAPS/STMAS hot-started analysis shows good impact on short-range forecast, specially at the beginning 0-3 hours; thus, it would help nowscastingand very short range forecasts, such as warn-on forecast, and convective initiation; • Further improvement of the hot-start and balance is underway for STMAS and LAPS as well. Workshop on Use of NWP for Nowcasting, Oct. 24-26, 2011

21. Statistics of real time run endedon Oct. 21, 2011 30 day statistics 7 day statistics Workshop on Use of NWP for Nowcasting, Oct. 24-26, 2011