Introduction to the EMC pre-implementation GFS/CFS parallel system

1. Introduction to the EMC pre-implementation GFS/CFS parallel system Shrinivas Moorthi

2. EMC GFS/CFS parallel jobs are run just like the NCEP operational jobs However, SMS used in the NCEP operations is not used The EMC parallel includes a global data assimilation cycle which involves assimilation of observations over a 6 hour window using a first guess from a 9 hour global forecast from a previous analysis. This is known as “gdas” cycle. Operational forecasts of 384 hours are made from a global analysis made with partial observations because of forecast window. This is known as “gfs” cycle Forecasts made from “gdas” analysis could be superior to that from a “gfs” analysis – CFSV2 forecasts are made from gdas cycle.

3. GFS/CFS scripts are very general Can be used to make just the “gdas” analysis Can be used to just make forecasts with given initial conditions Can be used to make coupled analysis or just the coupled forecast when the initial conditions are available.

4. Both the original global_post as well as the unified nceppost options are available. 3D diagnostic output is also possible for physics tendencies – nceppost posts 3D diagnostics VSDB verification package is available For long forecasts, options to write out monthly means and to extract time-series of selected variables is also available.

5. GFS/CFS Parallel System Structure

6. Users mostly have to create a “config” file like the file “para_config” in the “exp” directory. The name “config” could be anything and could be located anywhere on the computer Jobs are submitted using the “psub” command residing in the “bin” directory. This command needs four arguments - “config”, “cdump”, “cdate” and “step” “cdump” refers to the data dump where “gdas” is for the complete data dump and “gfs” is the data dump with early cutoff. Jobs can be submitted from any step

7. In NCEP operations we run GFS forecasts with two resolutions - A T574 forecast up to 192 hours and then aT384 forecast up to 384 hours. EMC parallel scripts can therefore run two segments (A three segment option is available, but not updated at this time) Some of the available steps are prep - data preparation step anal - data assimilation using GSI oanl - Ocean analysis using godas lanl - Land analysis using GLDAS fcst1(2) - first (second) segment forecast GFS/CFS post1(2) - first (second) segment post vrfy1(2) - first (second) segment verification arch - step for data archival

8. CFS parallel Scripts AM and OM Post post.sh Start here Copy IC files copy.sh 9 hr Coupled Model Forecast (first guess) GFS + MOM4 with Sea Ice MPI-level Coupling fcst.sh Verify vrfy.sh Expt website Prep step Hurricane relocation Data preparation prep.sh GODAS Global Ocean Data Assimilation oanl.sh Archive data arch.sh Seasonal Forecast? Time 00Z ? GDAS Global Atmospheric Data Assimilation GSI anal.sh GLDAS Global Land Data Assimi- lation lanl.sh Run seasonal Forecast fcst.sh

9. NCEP’s UNIFIED POST PROCESSOR (UPP) Hui-Ya Chuang

10. Introduction The Unified post (UPP) was developed as the common post processor for GFS, CFS, NAM, and WRF ARW. The use of a common post ensures that all model outputs at EMC are processed and verified the same way. UPP reads in model output in binary, GRIB, or netCDF format, and then generates output in GRIB.

11. Functions and features of UPPFunctions and features of UPP Performs verticalinterpolations onto isobaric and other non-model surfaces Computes diagnostic fields Destaggers wind onto mass points (WRF ARW) An MPI-parallel code

12. Fields generated by the UPP The UPP currently outputs 507 fields. Complete list in the subroutine RQSTFLD Sample fields generated by UPP: T, Z, humidity, wind, cloud water, cloud ice, rain, and snow on isobaric levels Shelter level T, humidity, and wind fields SLP (two kinds) Precipitation-related fields

13. Fields generated by the UPP Sample fields generated by UPP (cont.): PBL-related fields Diagnostic fields (e.g., simulated radar reflectivity and simulated satellite brightness temperature) Radiation fluxes Surface fluxes Cloud related fields Aviation products

14. Computation of isobaric fields Vertical interpolation of all state fields from model to pressure levels is performed in linear in ln(p) Underground vertical and horizontal wind components are specified to be the same as those at the first atmospheric model layer above ground. Underground temperature is reduced by assuming constant virtual potential temperature from the temperature averaged over the second and the third model levels above the surface.

15. Derivation of sea level pressure type I:standard NCEP SLP • Ground and sea level temperatures are extrapolated from the temperature at the lowest atmospheric layer by assuming a constant lapse rate of 6.5 K/KM. • Compute at ground and sea level and then apply Shuell correction to both s. The basic principal of Shuell correction is to make sure that s at both sea level and ground do not exceed a critical value. • Standard NCEP SLP is then derived as follows:

16. Derivation of sea level pressure type II:membrane NCEP SLP • Re-compute underground virtual temperatures by horizontally relaxing virtual temperatures on pressure levels: • The nine-point successive over-relaxation formula is used to solve the above Laplace’s Eq. numerically. • Once all underground virtual temperatures are generated, the hydrostatic equation is integrated downward to obtain sea level pressure.

17. Running UPP UPP needs three input files to run: itag: four-line file specifying details of WRF output to process wrf_cntrl.parm: control file specifying fields to output eta_micro_lookup.dat:look-up table for Ferrier MP In the sample scripts, these three files are generated on the fly or automatically linked.

18. Outputting fields on multiple levels UPP outputs fields on several vertical coordinates: Native model levels 47 default isobaric levels: 2, 5, 7, 10, 20, 30, 50, 70 hPa, then 75 to 1000 hPa every 25 hPa 7 flight levels above MSL: 914, 1524, 1829, 2134, 2743, 3658, and 6000 m. 6 PBL layers (values averaged over 30 hPa thick layers) 2 AGL levels: 1000 m and 4000 m for radar reflectivity.

19. Examples Output T every 50 hPa from 50 hPa to 1000 hPa: (TEMP ON PRESS SFCS ) SCAL=( 3.0) L=(00000 01001 01010 10101 01010 10101 01010 10101 01010 10000 00000…) From left to right, the isobaric levels go 2,5,7,10,20,30,50,70 then 75-1000 hPa every 25 hPa. To output instantaneous surface sensible heat flux: SFC SENHEAT FX) SCAL=( 3.0) L=(10000 00000 00000 00000 00000 00000 00000 00000 0000(INST 0 00000 00000…) To turn off cloud top height: (CLOUD TOP HEIGHT ) SCAL=( 3.0) L=(00000 00000 00000 00000 00000 00000 00000 00000 00000 00000 00000…)

20. UPP control file (PRESS ON MDL SFCS ) SCAL=(6.0) L=(11000 00000 00000 00000 00000 00000 00000 00000 00000 (HEIGHT ON MDL SFCS ) SCAL=(6.0) L=(11000 00000 00000 00000 00000 00000 00000 00000 00000 GRIB packing precision code keys on these character strings. Product description – post “1” = yes, “0” = no • Except for AGL and isobaric levels, vertical levels are counted from the ground surface up in gfs_cntrl.parm.

21. Examples Output T every 50 hPa from 50 hPa to 1000 hPa: (TEMP ON PRESS SFCS ) SCAL=( 3.0) L=(00000 01001 01010 10101 01010 10101 01010 10101 01010 10000 00000…) From left to right, the isobaric levels go 2,5,7,10,20,30,50,70 then 75-1000 hPa every 25 hPa. To output instantaneous surface sensible heat flux: SFC SENHEAT FX) SCAL=( 3.0) L=(10000 00000 00000 00000 00000 00000 00000 00000 0000(INST 0 00000 00000…) To turn off cloud top height: (CLOUD TOP HEIGHT ) SCAL=( 3.0) L=(00000 00000 00000 00000 00000 00000 00000 00000 00000 00000 00000…)

22. Sample Diagnostic fields Precipitation and derived Radar reflectivity

23. Sample Diagnostic fields Observed and derived GOES water vapor Ch observed water vapor ch simulated water vapor ch