Measurements of TRACER Pre-convective Conditions and Mesoscale Circulations Using Small Unmanned Aircraft Systems (sUAS)

Abstract

Convective clouds and the phenomena that support their development, govern a variety of climate-critical processes in the atmosphere.  How these phenomena are reproduced in climate models influences the extent to which simulated global climate reacts to forcing from increasing concentrations of atmospheric gasses. These clouds and the environments in which they form redistribute heat and energy in the atmosphere, and their presence changes the amount of energy reaching the Earth’s surface.  The accuracy with which these clouds and convective processes are represented in numerical models and the extent to which this representation governs the response of simulated climate to anthropogenic activities and impacts weather prediction has yet to be determined.  To better understand these relationships, the scientific community relies on observational field campaigns that target specific phenomena of interest to help evaluate and improve our predictive tools.

This project will contribute to one such field campaign – the “Tracking Aerosol Convection Interactions Experiment” (TRACER) project – by deploying a suite of instruments on small robotic research aircraft, also known as drones, unmanned aircraft systems (UAS), or remotely piloted aircraft systems (RPAS).  These platforms will operate in the greater Houston area to collect measurements of lower-atmospheric temperature, winds, humidity and aerosol properties.  Together with measurements collected by a variety of other instruments, these RPAS-based measurements will inform a variety of key research questions, including:

1. How do the properties of the pre-convective boundary layer control the formation and intensity of convective clouds?
2. How do environmental conditions influence the evolution of convective features, including eddies and clouds?
3. What impact does the Houston urban environment have on driving local circulations that support or enhance convective clouds?
4. How do the Galveston Bay breeze and Gulf of Mexico sea breeze properties influence formation of convective clouds?)
5. How do precipitation, land-sea breeze circulations (including bay breeze and gulf breeze), and the urban heat island impact aerosol particle amounts and their impacts on clouds and precipitation?

The RPAS systems to be deployed include the University of Colorado RAAVEN and the University of Oklahoma CopterSonde.  Both of these platforms have been deployed extensively for atmospheric research.  Teams will operate these platforms during the TRACER intensive operations period (IOP), with staggered two-week deployments planned during June through September 2021.  Measurements will be collected in the lowest kilometer of the atmosphere, and are planned to focus on the region between the city of Houston and the Gulf of Mexico to capture the full extent of the diurnal land/sea-breeze circulation.  Data will be prepared and documented for public dissemination and initial data analysis will focus on the evolution of the boundary layer and sea breeze in relation to convective cloud development.