Precipitation formation processes: a study about microphysics, aerosols interactions and cloud life cycle using radar and airplane data

Abstract

This work aims to understand Amazonian cloud and precipitation formation and the evolution of their microphysical properties. The scientific objectives to be treated are in line with those of the projects GOamazon, CHUVA (FAPESP 2009/15235-8), IARA (Intensive Airborne Experiment in Amazonia) - Feb-Mar/2014 and ACRIDICON (Aerosol, Cloud, Precipitation and Radiation Interactions and Dynamics of Convective Systems) - Sep-Oct/2014. Those projects intend to provide observation to improve the scientific understanding of biogenic and anthropogenic aerosols (and their interactions), precipitating systems characteristics and aerosol-cloud-precipitation interactions over the Amazon basin region. The intensive operations periods (IOP) IARA (aircrafts Gulsftream-1 - G-1 and ACRIDICON-CHUVA (aircraft G-5 - HALO - Height Altitude and Long Range Aircraft and G-1) include flight plans to measure aerosols and clouds properties. The student is expected to visit the Leipzig Institute of Meteorology (LIM) after the ACRIDICON campaign to analyze data collected by the HALO aircraft. The various particles size distributions (PSD) of the different hydrometeors (rain/cloud droplets, various kinds of ice crystals) will be characterized. The complete data set consisting of aircraft, radar and disdrometer measurements will allow to observe those properties in varying levels of altitude and through the cloud life cycle. The PSDs will be parameterized with the moment method, by fitting a 3-parameter gamma function to each individual distribution. Those parameters will be used to illustrate the Manaus pollution plume impacts on convective systems. One of the main objectives of this work is to identify the characteristic microphysical properties of clouds that develop into deep systems and evaluate if they have a significant influence on this growth. It's expected that the cloud microphysical properties during its formation are significant for the developed cloud structure such as the height and depth of the mixed layer and crystals habits. For instance, clouds that present relatively small droplets (such as the polluted ones) tend to suppress contact and immersion freezing and can delay the formation of the mixed layer, which would then be higher and thinner. This process will be explored using a multispectral probe installed on aircraft that observe clouds laterally. With this, it's intended to build a conceptual model regarding cloud structure (layers, crystals habits) as a function of parameters such as season, thermodynamic conditions and aerosol loading. (AU)