NAME Tier 1 Atmospheric/Ocean Process and Budget Studies Richard H. Johnson, Paul E. Ciesielski, Brian McNoldy Colorado State University 6 March 2003 NSF
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 2003 NSF
Tier I is a focal point for regional-scale processes… processes linked to objectives of Tiers II and III mm 6 March 2003 NSF
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? ~ 8 m s-1 Brenner (1974) 6 March 2003 NSF
Gulf of California Surges Meridional flow from QuikScat Head of Gulf Mouth Many surges originate at mouth of Gulf 6 March 2003 NSF
Expanded view, June—mid-July ~ 7 m s-1 July 4-8 surge 6 March 2003 NSF
July 4-8, 2000 GULF SURGES 6 March 2003 NSF
To what extent does cooler air that passes around the southern tip of Baja contribute to surges? BEFORE POES AVHRR/HIRS AFTER 6 March 2003 NSF
TRMM 3B42 6 March 2003 NSF
Much of the world’s heaviest rainfall occurs in coastal environments 6 March 2003 NSF
Garreaud and Wallace (1997) Tb235 K Garreaud and Wallace (1997) SSM/I data 6 March 2003 NSF
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 2003 NSF
Processes producing nocturnal offshore rainfall maximum are not well understood Mapes et al. (2003) 6 March 2003 NSF
TIER 1 SOUNDINGS = NOAA R/V Ronald Brown 6 March 2003 NSF US 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 2003 NSF NOAA ETL surface flux system RAOB Budget network
• 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 2003 NSF
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 2003 NSF
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 2003 NSF