Sensitivity of the NCEP CFS to Localized Soil Moisture Anomalies

1. Sensitivity of the NCEP CFS to Localized Soil Moisture Anomalies Huug van den Dool and Suranjana Saha CPC and EMC/NCEP

2. What is CFS?The NCEP Climate Forecast System (CFS). T62L64 Global Coupled Ocean Atmosphere Land System. Original Hindcasts: 25 (1981-2005) times 12 (initial months) times 15 ensemble members times 9 (months for each run) =~ 3400 years of model world realizations. Ref: S. Saha, S. Nadiga, C. Thiaw, J. Wang, W. Wang, Q. Zhang, H. M. van den Dool, H.-L. Pan, S. Moorthi, D. Behringer, D. Stokes, M. Pena, S. Lord, G. White, W. Ebisuzaki, P. Peng, P. Xie , 2006 : The NCEP Climate Forecast System. In press, J. Climate. (It is already e-available at AMS site) All CFS info is at http://cfs.ncep.noaa.gov/

3. Background of Soil Moisture Experiments: • In search of areas of strong land - atmosphere interaction. Approaches: -) Real World Empiricist -) Model World Empiricist -) Numerical Model Runs (mostly!)

4. Suppose we have a land domain which has climatological soil moisture everywhere, except in a small patch (radius, lat/lon position, peak value). Q: What will the effect of this anomaly patch be on subsequent T, E, P ??? Posed this way ‘attribution’ is ‘easier’ than when a realistic soil moisture anomaly distribution were used. Land Domain Wet or dry patch

5. wIC(s, t0) =~ wCA(s)= Σ α(t) w(s,t) t Where summation t is over years past. Real world CFS world

6. Real world CFS world

7. In order to do patch experiments with a numerical model we need to first make climatology runs (they function as climatology runs regardless where we place the patch). In order to do the climatology runs we need to know what the climatology is, which requires a data set based on standard integrations such as the original CFS runs. In summary: • Set of standard runs (Control) February (IC) - End of August, 1981-2005. Extract Model Climatology of soil moisture (levels in the vertical and snow depth) in May. • Make climatology runs April 29 – May 3 (5 ICs) out till end of August for 2000-2004. (tier 1) • As 2, but now a patch added at the initial time. • Call this set of model runs an experiment.

8. Exp I: CFS@T62, OSU land model (R2 Initial Conditions) EXP II: CFS@T62 and Noah land model (G-LDAS Initial Conditions) EXP III: CFS@T126 and Noah land model

9. Example of EXP I, patch over India

12. Interactive patch runs maintain a soil anomaly patch until the end of summer. Exps done as tier-1, not AMIP-style.

13. Interactive patch runs maintain a soil anomaly patch until the end of summer. Exps done as tier-1, not AMIP-style.

14. Example of EXP I, patch over US

15. Example of EXP I, patch over US. Sensitivity to soil model???

16. Example of EXP I, patch over US. Sensitivity to sign of the anomaly.

17. Further detail on model runs. • We placed the patch in Numerical Experiments over a) USA, b) India, and c) Africa (three locations guided by Koster et al 2004 hot spots). • We do p1, p2 and m1 runs to gauge linearity/symmetry • Numerical experiments are costly. Hopefully the CA can be used to approximate model behavior. (We have three locations to verify CA). This will allow us to move the patch (any patch) to any location in any season, and systematically detect areas that are sensitive to land-atmosphere interaction. Also SH! Koster et al result

18. More General (non-patch) Analysis on Climo (2) vs Regular Control (1) runs, or, what is the general impact of soil moisture anomalies?. • Monthly mean data 1981-2005. Remove (own) climatology. Then study… • The world is a single number

19. Tell-tale parameters to analyze: • Variance • Persistence • Cross-correlations (w, T) • Predictability (4 member ens mean vs 5th member left out) • Prediction skill (5 member ens mean vs ‘reality’ (R2, CMAP, CAMS) )

20. Does the variance increase? Yes. Realistic initial w conditions (April 30-May 3) increase the variance in w (by design initially) over climo runs, E (all the way thru August), Tmax and T2m (in May and June mainly)….. Impact not clear on Precip, surface pressure ….

22. Does month-to-month persistence increase? Yes. Initial w conditions (April 30-May 3) increases persistence in w and E (all the way thru August), Tmax and T2m (in May and June mainly)….. Impact not clear on Precip, surface pressure …. (may need less blunt tools)

23. Also to be looked at: • The hydrological equation, the energy equation, the boundary layer…the physics • Recycling??

24. Total number of runs : • EXP I • 0. CFS 25 years x 5 IC's = 125 (6-month runs), already done in 2004 • CFS CLIMO = 25 years x 5 IC's = 125 (4-month runs) • CFS+PATCH U.S. = 5 years x 5 IC's x 3 patches = 75 (4-month runs) • CFS+PATCH India = 5 years x 5 IC's x 3 patches = 75 (4-month runs) • CFS+PATCH Africa = 5 years x 5 IC's x 3 patches = 75 (4-month runs) • EXP II • CFS+NOAH = 25 years x 5 IC's = 125 (6-month runs) • CFS+NOAH CLIMO = 25 years x 5 IC's = 125 (4-month runs) • CFS+NOAH PATCH U.S. = 5 years x 5 IC's x 3 patches = 75 (4-month runs) • CFS+NOAH PATCH India = 5 years x 5 IC's x 3 patches = 75 (4-month runs) • CFS+NOAH PATCH Africa = 5 years x 5 IC's x 3 patches = 75 (4-month runs) • ---------------------- TOTAL = 825 runs (4050 months, 337.5 years !!) -------------------- • EXP III: as II, but T126.

25. Does CA work???