Mechanisms of convective cloud organization by cold pools over tropical warm ocean during the AMIE/DYNAMO field campaign

Citations Over TimeTop 10% of 2015 papers

Abstract

Abstract This paper investigates the mechanisms of convective cloud organization by precipitation‐driven cold pools over the warm tropical Indian Ocean during the 2011 Atmospheric Radiation Measurement (ARM) Madden‐Julian Oscillation (MJO) Investigation Experiment/Dynamics of the MJO (AMIE/DYNAMO) field campaign. A high‐resolution regional model simulation is performed using the Weather Research and Forecasting model during the transition from suppressed to active phases of the November 2011 MJO. The simulated cold pool lifetimes, spatial extent, and thermodynamic properties agree well with the radar and ship‐borne observations from the field campaign. The thermodynamic and dynamic structures of the outflow boundaries of isolated and intersecting cold pools in the simulation and the associated secondary cloud populations are examined. Intersecting cold pools last more than twice as long, are twice as large, 41% more intense (measured with buoyancy), and 62% deeper than isolated cold pools. Consequently, intersecting cold pools trigger 73% more convection than do isolated ones. This is due to stronger outflows that enhance secondary updraft velocities by up to 45%. However, cold pool‐triggered convective clouds grow into deep convection not because of the stronger secondary updrafts at cloud base, but rather due to closer spacing (aggregation) between clouds and larger cloud clusters that form along the cold pool boundaries when they intersect. The close spacing of large clouds moistens the local environment and reduces entrainment drying, increasing the probability that the clouds further develop into deep convection. Implications for the design of future convective parameterization with cold pool‐modulated entrainment rates are discussed.

Related Papers

• → Seeding Convective Clouds with Hygroscopic Flares: Numerical Simulations Using a Cloud Model with Detailed Microphysics(2000)83 cited
• → Cloud physics and cloud water sampler comparison during FEBUKO(2005)41 cited
• → A model of the development of the droplet spectrum in a growing cumulus turret(1986)22 cited
• → Droplet Activation as Related to Entrainment and Mixing in Warm Tropical Maritime Clouds(1993)13 cited
• THE SOUTHERN PLAINS EXPERIMENT IN CLOUD SEEDING OF THUNDERSTORMS FOR RAINFALL AUGMENTATION (SPECTRA) PROJECT: OPERATIONAL TOOLS USED TOWARDS VERIFYING GLACIOGENIC AND HYGROSCOPIC SEEDING CONCEPTUAL MODELS, CASE STUDIES AND PRELIMINARY RESULTS.(2004)