1. Project Title: Medium-Scale Atmospheric Waves: Coupling of Convection, Clouds and Larger-Scale Dynamics PI: M. Joan Alexander NorthWest Research Associates, Colorado Research Associates Division

2. Waves Generated by Latent Heating in Convection: Holton [1972; 1973] – Latent heating as source for observed Kelvin and Rossby-Gravity Waves Salby & Garcia [1987] - Wave properties are most sensitive to the depth of the heating, not profile shape Bergman & Salby [1994] - Wave response using Global Cloud Imagery as proxy for heating (lat,lon,z,t) Wheeler & Kiladis [1999] - OLR as proxy for heating projects strongly onto wave dispersion curves Ricciarduli & Garcia [2000] - Wave response from latent heating in the CCM3 global model Horinouchi et al. [2003] - GCM intercomparison of wave modes and relationship to parameterized convection

3. Horinouchi et al. [2003] GCM Intercomparison Their figure 4 shows 2d zonal wavenumber and frequency spectra of: Left: Precipitation rate Center: Vertical component of wave EP-flux at 65 hPa Right: EP-flux at 1 hPa AS KU TN ZM GR CA

4. Lagrangian Balloon Observations [Vial et al., 2001] Observations show a pronounced westward propagating wn=4, 4-day Rossby-gravity wave (6-day intrinsic period) that is also present in ECMWF winds but at much weaker amplitude and inaccurate phase. The large-amplitude wave was short in duration lasting only ~10 days and had a short vertical wavelength ~2.5 km that could not be modeled accurately with ECMWF resolution. Zonal Wind Temperature Meridional Wind

5. Small-Scale Gravity Waves Generated by Convection: Holton & Durran [ 1993] – 2d cloud-resolving model study with gravity waves in the stratosphere Alexander et al. [1995] - Wave properties closely related to the depth of the heating Holton et al., [2002] - Wave properties determined by 4d (x,y,z,t) heating properties Chun & Baik [1998; 2002] and Beres et al. [2004; 2005] - Convectively generated gravity wave parameterizations for GCMs Alexander et al. [2004] - Wave response from 4d precipitation radar data as proxy for heating Alexander et al. [2005] - Observation-based improvements to the parameterizations

6. 4d radar precipitation Input to mesoscale model Wave analysis Modeled wave fields Model domain Verify with observations Model & BL Radar Wind Comparison 2d Wave Spectrum 2d parameterized spectra 1 3 2 Param. improve- ment Ex: process study that improved GCM parameterization

7. Satellite Observations of Waves: Traditional Kalman filter analysis gives wavenumbers 1-6. Aura measurements with modern analysis tools can extend wave observations to smaller horizontal and vertical scales: “Medium-scale waves” including large-scale gravity waves. CloudSat with other A-Train measurements can provide global information on precipitation and latent heating structure at far higher spatial resolution than earlier proxies, and provide vertical structure information. These new data sets with model tools can provide state-of-the-art theoretical predictions of medium-scale wave properties and observational verification to test and improve GCM treatment of waves generated by convection.