1. Issues for regional modeling
Hugo Berbery
and
Wayne Higgins, Dave Gutzler, Dave Gochis

2. NAME DELIVERABLES
Observing system design for monitoring and predicting the
North American monsoon system.
More comprehensive understanding of North American
summer climate variability and predictability.
Measurably improved climate models that predict North
American monsoon variability months to seasons in advance.
What is the best strategy for improvements in operational climate prediction of warm season precipitation?

4. MULTI-SCALE MODEL DEVELOPMENT
Premise
The leading factors that limit precipitation forecast skill in both
global and regional models during the warm season are deficiencies
in how we model “local” processes that modulate deep convection.
In order to achieve the desired improvements, NAME will focus on
-land/atmosphere interactions in the presence of
complex terrain and land/sea contrasts;
- moist convection in the presence of complex terrain
and land/sea contrasts;
- ocean/atmosphere interactions in coastal regions with
complex terrain

5. 9 Recommendations for NAME
CLIVAR SSC -
9 Recommendations for NAME
Scientific
Determine role of oceanic processes (e.g. regulation
of moisture supply) in the dynamics of the monsoon.
Increase emphasis on relevant marine data to
support monsoon modeling and the interpretation
of continental observations.
Ocean
Processes
Land
Surface
Processes
Enhance land surface observations and
modeling including land data assimilation.
Develop cloud modeling strategy to study precipitation over complex terrain and the behavior of convection over warm continents, key issues in model development.
Modeling
Climate Studies

6. NAME will have much to gain if a workstation-based (Linux) DAS becomes
- Notable advancements in understanding mesoscale processes
are the result of the widespread availability of regional
models (MM5, Eta, RAMS…).
- However, there are some aspects that are yet not well
understood because there are no clear diagnostics of the
phenomena.
- To be of best use, observations need to be blended
into a consistent and balanced multi-variable data set:
this is the purpose of a data assimilation system.
NAME will have much to gain if a
workstation-based (Linux) DAS becomes
available to the research community.

7. Strategy and Tools Regional modeling Data assimilation Modeling
Diagnosis
Data
assimilation

8. Phenomena with a role in the evolution/maintenance of the NAM
- The diurnal cycle
- Low level jet
- Surges
- Surface processes (Land; Ocean/Gulf) – Heat low?
- MCCs

9. Resolution issues:
Dynamical Core
Physics

10. Parameterization issues: Gochis et al. 2002
Kain-Fritsch
B-M-J
Grell
PERSIANN

11. The diurnal cycle

12. The diurnal cycle
The critical role of the diurnal cycle in model simulations is emphasized here. The arrows represent the moisture fluxes estimated from Eta model analyses. The afternoon maximum fluxes into land are followed by large convective precipitation over the western part of Mexico. Satellite estimates of precipitation have been used.

13. The diurnal cycle of moisture flux convergence
EDAS 1995/1997

14. NAMAP

15. Gochis et al. 2003 The diurnal cycle from precipitation observations
0.2
0.4
0.6
0.8 1
1.2
1.4
1.6
1.8 2 4 6 8 10 12 14 16 18 20 22 24
Time of Day (LST- Local Solar Time)
Precipitation Rate (mm/hr)
Network Mean (n=47)
0-500 (n=14)
(n=10)
(n=1)
(n=9)
(n=11)
(n=2)
Gochis et al. 2003

16. The low-level jet

17. ETA

18. The diurnal cycle
The critical role of the diurnal cycle in model simulations is emphasized here. The arrows represent the moisture fluxes estimated from Eta model analyses. The afternoon maximum fluxes into land are followed by large convective precipitation over the western part of Mexico. Satellite estimates of precipitation have been used.

19. Transients and surges

20. Transients and surges
Transient fluxes supply moisture to the southwestern United States. These transients are mostly the result of moisture surges along the Gulf of California, usually due to the passage of easterly waves and tropical storms.

21. SG GCM – summer 1993 Great Plains LLJ Gulf of California LLJ
(Along the Gulf)

22. Surge
No surge
Percentage of precipitation over the southwestern United States due to surge events (lower left panel).
Percentage of precipitation due to non-surge cases

23. Percentage of total precipitation
Surge
No Surge

24. Surface processes

25. High resolution LDAS needed. Apply here
How are surface processes represented
in regional models?
- Vegetation/soil moisture/etc over sloping terrain
- Surface Fluxes
High resolution LDAS needed. Apply here
Do the Gulf of
California SSTs
have an effect on
the local circulations?
Evaporation?

26. Final comments (1)
What we have today:
- Different types of observations are (or will become) available.
- Regional models are available.
The missing link:
A user friendly Data Assimilation System for research/application purposes.

27. Final comments (2) 1. A comment on the diurnal cycle studies:
The study of the diurnal cycle of surface fluxes should go before the study if the diurnal cycle of convection/precipitation (Surface fluxes over land and over the Gulf).
And what is the diurnal cycle of MCCs and surges?
2. Verification issues:
Let’s not confuse observations with truth

28. 1. Can we identify what is failing in models in the core monsoon, but is working in other regions?
2. Can we identify if the failure is dynamical or physical?