1. Yuanfu Xie, Steve Albers, Hongli Jiang Paul Schultz and ZoltanToth
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 , 2011

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

3. LAPS and STMAS 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.
Workshop on Use of NWP for Nowcasting, Oct , 2011

4. A multigrid approach Sequence of 3-4DVARs with proper balances
Similar to LAPS analysis with less requirement of covariance
Standard 3-4DVAR
With a band covariance
Possible ensemble
Filter application
Long waves
Short waves
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
OAR/ESRL/GSD/Forecast Applications Branch

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
OAR/ESRL/GSD/Forecast Applications Branch

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

7. LAPS HOT START INITIALIZATION
Three-Dimensional Cloud Analysis
F H
F L
METAR
+ FIRST GUESS

8. Hot-start components 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.
Workshop on Use of NWP for Nowcasting, Oct , 2011

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

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

11. 6-hr Diabatically (LAPS) initialized
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 , 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 , 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 , 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 , 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 , 2011

17. Forecast at 2011-09-04 00Z ETS Bias 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 , 2011

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

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