Ensembling Mesoscale Model Data

1. Ensembling Mesoscale Model Data National Weather Service, Cleveland, OH Christopher Mello

2. The goal of this presentation is to describe WRF ensembling software that produces an ensemble for OPERATIONAL use across a computer network with limited bandwidth resources.

3. Motivation for Software ? • There was a need to share large amounts of model data between NOAA NWS offices with limited computer and bandwidth resources. • There was an operational requirement to present all this model data in timely and precise manner to weather forecasters.

4. Ensemble Example

5. Ensemble Domain

6. WRF model • Locally produced WRF mesoscale model data grib files contain over 700 fields and are too large to transport across the NOAA NWS computer network due to bandwidth Issues • However, the vast majority of the fields are considered not directly useful for operational weather forecasting

7. What was the best way to present data to forecasters? • Mean fields were operationally the easiest method to get data directly to forecasters due to the current state of NWS software. • Probability fields fields were created as secondary fields but due to the current state of NWS software could not be easily ingested into current NWS forecast software

8. What data is the most important for forecasters? • A default list of 52 critical operational meteorological fields from the WRF model was created using input from six NWS WFO sites. • At least 40 additional fields could be derived later using current image generating software

9. Mean Fields

10. Probability Fields

11. CLENSEMBLE uses GEMPAK • GEMPAK software was used to create the ensemble due to cost and the teams experience using the software. • GEMPAK Developers continue to add new ensemble functionality. • The direct access to developers made trouble shooting GEMPAK problems easier.

12. Part One:Dissect software • The dissect software is required to reformat each ensemble member’s grib files to a GEMPAK format • The domain and grid spacing of the final ensemble has to be defined in a configuration file. • The dissect software will resize each member’s domain and spacing to the domain of the ensemble

13. Part One:Dissect software • 52 fields are extracted • The files are approximately 5 % of the original size

14. Part Two: Create Ensemble • Ten WRF members can be placed in an ensemble at a time • When creating means fields, each ensemble member is given a weight from 0 % to 100 % in a configuration file • The total weights of all the members must equal 100 %

15. The previous runs can be included if the data are available The data output of the mean ensemble fields is in three different formats; GEMPAK, grib1 and grib2 format. Grads imaging software is included to create gif images of the mean fields

16. Mean surface wind in NWS GFE software

19. Probability fields • The probability fields are produced as gif images • Each model member is weighted equally • Future upgrade will included 6, 12 and 24 hour QPF probabilities fields in grib2 format

20. Probability of small craft advisory winds

21. Probability of getting .05 inches through 30 hours

22. Summary • CLENSEMBLE is an operational tool to provide real time model data to forecasters • CLENSEMBLE provides forecasters with approximately 100 fields • National Weather Service Offices can share resources with forecasters • The academic community can also provide NWS forecasters real time model data

23. …Continued… • Also 6,12, and 24 probability fields will be provided in a future release

24. Finally • The software is in a developmental state and input to improve future builds is welcome.

25. Acknowledgements • Robert Laplante SOO Cleveland NWS • Dan Leins WRF focal point CLE NWS • Ron Murphy ITO BGM

26. The End… Thank you Questions, Comments, Concerns… Feel free to e-mail Christopher.mello@noaa.gov Or Robert.laplante@noaa.gov