1. NAME Tier 1 Atmospheric/Ocean Process and Budget Studies
Richard H. Johnson, Paul E. Ciesielski, Brian McNoldy Colorado State University
6 March NSF

2. NAME Scientific Objectives in a Nutshell
Large Scale
Life cycle of NA summer monsoon – mechanisms and prediction
Relationship between precipitation and seasonal evolution of continental and oceanic boundary conditions
Intraseasonal variability of precipitation; interannual variability and relationship to ENSO
Representation (parameterization) of key processes in climate models
Regional and smaller scales, but central to large-scale issues
Dynamical and microphysical characteristics of precipitation systems
Diurnal cycle of precipitation
Precipitation processes in complex terrain
Mechanisms of Gulf Surges, role of air-sea exchanges in water vapor transport to Southwest U.S., upper ocean variability in response to surges
6 March NSF

3. Tier I is a focal point for regional-scale processes… processes linked to objectives of Tiers II and III mm
6 March NSF

4. Gulf Surges: moisture transport to SW US
July 1972
Fuller and Stensrud (2000)
Some surges are linked to easterly waves, some to tropical storms
What triggers surges? Possibility: convection and downdraft outflows
What is role of local evaporation vs advection in the moisture budget?
Surge propagation: coastal gravity currents or other mechanism(s)?
How does the upper ocean influence and respond to surges?
~ m s-1
Brenner (1974)
6 March NSF

5. Gulf of California Surges
Meridional flow from QuikScat
Head of Gulf
Mouth
Many surges originate at mouth of Gulf
6 March NSF

6. Expanded view, June—mid-July
~ 7 m s-1
July 4-8 surge
6 March NSF

7. July 4-8, 2000
GULF SURGES
6 March NSF

8. To what extent does cooler air that passes around the southern tip of Baja contribute to surges?
BEFORE
POES AVHRR/HIRS
AFTER
6 March NSF

9. TRMM 3B42
6 March NSF

10. Much of the world’s heaviest rainfall occurs in coastal environments
6 March NSF

11. Garreaud and Wallace (1997)
Tb235 K
Garreaud and Wallace (1997)
SSM/I data
6 March NSF

12. Diurnal cycle of convection – a continuing enigma
“…an accurate representation of the diurnal cycle over land and ocean provides a key test of many aspects of the physical parameterizations in a climate model. The Met. Office Unified Model has demonstrated considerable difficulty in capturing the observed phase of the diurnal cycle in convection.”
Yang and Slingo (1997 MWR)
6 March NSF

13. Processes producing nocturnal offshore rainfall maximum are not well understood
Mapes et al. (2003)
6 March NSF

14. TIER 1 SOUNDINGS = NOAA R/V Ronald Brown 6 March 2003 NSFUS I US US
88D I US M5 M
88D M US M5
88D I M5 I M US M M5
10P M M M5
= SMN 5 cm Doppler Radar
88D
= WSR 88D Doppler Radar
10P
= S-band Dual-Pol. Radar M
= SMN Op. RAOB US
= U.S. Op. RAOB I
= ISS Profiler/ RAOB
= UHF Profiler w/RASS M M M M
= NOAA R/V Ronald Brown
5 / .85 cm Dopp. Radars, Profilers, RAOB, Fluxes, aerosols, SST/CTD/ADCP M
6 March NSF
NOAA ETL surface flux system
RAOB Budget network

15. • NCAR ISS (GPS sounding, UHF profiler, RASS, sfc station)
Sounding network designed to determine:
– initiation mechanisms, structure, and propagation of surges
– mechanisms for diurnal cycle
– air-sea exchanges, upper-ocean changes
– atmospheric budgets, latent heating profiles over land and ocean •
• Mexico soundings
 UHF profiler w/RASS • • •  • • • • • •
fluxes, upper-ocean
6 March NSF

16. Environmental response to convection depends on vertical distribution of heating
Impulsive heating W H P
Combined Heating L
Nicholls et al. (1991) b
6 March NSF

17. CONCLUSIONS
TIER I will provide data that will enhance basic understanding of phenomena of this region, as well as contribute to prediction and climate objectives of NAME
Within a climate context, many of the smaller-scale processes such as the diurnal cycle, surges, etc., are highly nonlinear
Specifically, the application of a mean solar zenith angle (rather than the diurnal cycle) or mean flow conditions (rather than surges) may yield a quite different distribution of precipitation and climate than the representation of the full dynamic ranges of these phenomena
6 March NSF