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. 24-26, 2011

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. 24-26, 2011

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. 24-26, 2011

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. 1224-1240 OAR/ESRL/GSD/Forecast Applications Branch

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

Cloud Analysis Flow Chart Cloud Fraction 3-D Isosurface

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

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. 24-26, 2011

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

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

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

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

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

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

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

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

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

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

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

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

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