Breakout Session 3: Analysis Strategies

1. Breakout Session 3: Analysis Strategies • Charge(s): • Identify and evaluate the current capabilities to develop AORs • Recommendations on overcoming current analysis/assim problems (relevant science issues)

2. ‘Complete’ analysis systems • NCEP/WRF: 3DVAR (GSI) with WRF (assimilating model). Computer time issues (NCEP perspective). Avoids downscale issues if model run at high resolution. Precip. Would be stage 4 product (at 4 km hz. resolution). • FSL/RUC: Downscale RUC (NOHRSC) + Analysis. Computational issues are not excessive. • MSAS/RSAS: OI (P. Miller) • LAPS: Component of AWIPS platform (as well as stand-alone). Computationally efficient • STMAS: Real-time diagnostics w/ model background that is downscaled as much as possible. Origins from LAPS (currently 2D with intent to ingest radial winds and reflectivity into a 3D analysis) • ADAS: OI-type scheme that is computationally inexpensive. Currently in use operationally at NWS Melbourne, U. Utah, U. Oklahoma • RTFDDA: 4DVAR (obs nudging) from NCAR/RAP.

3. Component analyses • NMQ: Real-time 1 km precipitation products every 5 min, • rate/type/phase/accumulation. Possible alternative to NCEP’s stage 4 • product (Jian Zhang/NSSL). Production of national mosaic for • precipitation and 3d reflectivity. • 2DVAR/QC: QC of radial winds and reflectivity (NSSL/Qin Xiu). Developed for real-time applications. (could be part of AOR data QC process). Although not directly applicable to current NDFD validation fields, winds might be useful for shear estimates or for other relevant (and future) forecast products, e.g. freezing level estimates. • LDAS: Land surface data assimilation system (NCEP). Goal: uses precip. to remove uncertainty from the surface energy budgets. • Satellite Products/Systems: (Bob Aune)

4. Questions Posed: Strict Interpretation: Is this a surface only analysis or not? If 3D, what is the depth of the AOR analysis? AOM vs AOR? How much more data would come in for delayed analysis? How fast can ‘data’ be delivered? If the downscaling works (NOHRSC) - why isn’t it used in NWS smart init? How to deal with mesoscale (meso-gamma) weather? Are there any proprietary issues regarding the data (i.e. can an NWS office share data with national center)?

5. More Questions How do we best transfer the large volumes of surface data (and in some cases profiler data) into the pbl? Should there be a local digital data base as well? Where would AOR run? Downscale advocates: How to best accomplish this (validation issues)? Will downscaling make background field worse? How does the technology transfer happen? “Make it so” Is a 1 hour forecast sufficient to avoid the spin-up issue (if one exists)?

6. Issues Rapid (quick delivery) vs Final Product Diagnostic vs Full 3D/Forecast Diagnostic (2D/surface vs 3D) Probabilistic (estimate of uncertainty in analyses) Real-time vs. delayed real-time Model init. different problem than producing a verification grid. Covariance specification is an obvious issue Convection ->Adding/Shifting/Removing: Will assimilation of observed data with high temporal resolution limit these problems in the initial guess? Need good error variance estimates. Convection is potential contamination at coarse model resolution Forecasters need quick assessment information PDF analyses (future?). No probabilistic information in the NDFD Removing gross errors from the background field

7. Issues Cont’d The transfer of information (to NCEP) regarding analysis issues with other systems (e.g. LAPS or ADAS). “Lessons Learned” Mesoscale analysis testbed (regional)? QC ISSUES IMPORTANT: Issue of ‘subjective’ analysis of some of the data (e.g. weeding/blacklisting bad data). Passing this information from the local offices onto NCEP. NWSFO paradigm - 0/24 h forecast interval ‘highly analyzed’ NWSFO office will adjust GFE grids in response to all he observations. Arrange to send QC info from local offices to NCEP. Referred to as ‘intervention’ (need metadata to pull this off). Forecaster ‘continuity’ issues. ‘Additional’ QC efforts at NCEP showed little effect on the GFS forecasts For RUC QC, mesonet observations are not used to corroborate one another and instead METAR are used to corroborate mesonet.

8. Wrap Up Evaluation/Validation (bootstrapping) Timeliness of a Dec. 2004 deliverable? Relationship of short-term product vs. long-term product Will the delayed analysis involve both more obs and a more sophisticated analysis system?

9. Recommendations… Planning, development, testing, & implementation A. Short term efforts 1. Form ‘mesoscale analysis’ committee 2. NCEP produce simple 2D analysis product 3. FSL principals work to assist NCEP using features of current RUC, LAPS, MSAS, STMAS systems 4. Research begins on effectiveness of downscaling techniques (NOHRSC, PRISM) 5. Begin planning validation of analysis 6. Two analyses should be produced (AOM ~ 30 min, AOR ~ 24 h)

10. B. Longer term efforts 1. Decide on which 3D data assimilation/modeling system to use 2. Develop x-validating verification system 3. Use complete radar and satellite data sets (used QC approaches developed by NSSL for vr and Z) 4. Develop techniques to produce uncertainty estimates of analyses (e.g., EnKF, “Probalistic Analyses”)

11. Plenary/Wrap Up Questions, Issues & Concerns Will the short-term efforts relfect longer-term goals and objectives? Error structure changes as model changes/evolves or more observations and different observation types are added to assimilation system etc. (error statistics stability). Community analysis system? Mapping of model state variables (that are not explicitly predicted by the model) to desired NDFD validation variables (e.g., visibility) Consider what variables a given analysis system produces (Excel spread sheetmatrix). Analysis interpretation, e.g., what does a grid point value represent? December analyses should be a system already in use? Capture real-time data at full resolution (e.g., ASOS records at 1 min. but reports hourly) What data goes into the analysis?