Aircraft and Surface Observations of Aerosol and Cloud Properties during HEAT

 

Abstract

The Houston Environmental Aerosol Thunderstorm Project (HEAT) is designed to address the factors responsible for the observed enhancement in lightning frequency over Houston, TX. An array of surface and airborne equipment will be operated during this study to characterize the thermodynamic, environmental, and cloud properties of the atmosphere within and outside of the urban area. It has been hypothesized that enhanced aerosol concentrations arising from urban emissions suppress precipitation and deepen the mixed layer within urban clouds, which may alter cloud electrification, and possibly increase lightning frequency. To address the merit of this hypothesis for the Houston region, detailed measurements of aerosol and cloud properties will be necessary. We propose to augment data collected from other platforms with complementary aircraft and surface measurements of aerosol and cloud properties throughout the 6-week intensive. Nearly identical instrumentation suites will be used on a Cheyenne II aircraft and at a surface site in the Houston area to characterize size distributions, size-resolved hygroscopic growth, and cloud activation efficiency of the local aerosol. The aircraft will also be equipped with multiple wing probes for direct measurement of cloud droplet size distributions.

Broader Impact:

The underlying motivation for this study is to better understand aerosol- cloud interactions. The emphasis in the HEAT study is on the influence of the aerosol on cloud electrification, but the measurements made and analyses conducted will also benefit the study of the indirect effect of aerosols on climate. This project will also provide field experience for both graduate and undergraduate students. One graduate student will be responsible for much of the data collection and analysis activities involved in the study, while undergraduates enrolled in the NSF supported “Field Measurements in the Atmospheric Sciences” summer course Dr. Collins teaches each year will have the opportunity to travel to Houston to participate in the project and analyze aircraft and surface data.