TRACER-MAP: Mapping Aerosol Processes Across Houston During Convective Cell Events

Introduction

Thunderstorms and precipitation can be affected by small aerosol

aerosols

Small particles or droplets, such as wildfire smoke, volcanic gases, or salty sea spray, that float in the air. They are emitted by both natural events and human activities.

Source: NASA Global Climate Change Source

particles emitted and produced by urban and industrial pollution sources. There is still a lot that scientists do not understand about these interactions and how important urban pollution is in convective storm initiation and activity (convection

convection

The rising of warm air and the sinking of cool air. Convection can cause local breezes, winds, and thunderstorms.

Source: NASA earth observatory Source

is the broad term that describes the vertical motion that initiates thunderstorms). The Houston, TX Metropolitan area was selected for the 2021 Tracking Aerosol Convection Interactions Experiment (TRACER) due to its high convective storm activity and broad range of polluted aerosol conditions. With the overall TRACER project in mind, we planned TRACER-MAP, a related investigation of the impacts of convective storms on atmospheric composition, chemistry and aerosol processing in Houston. Because the Houston metroplex is large and has a wide range of atmospheric conditions, this project will “MAP” the air chemistry conditions across Houston while atmospheric scientists working in the TRACER project monitor convective storm activity overhead. Specifically, we will conduct a series of aerosol, gas, and meteorological measurements in the summer of 2021 that will match measurements from the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Mobile Facilities.
Methods. We will locate our instruments and make measurements at established air monitoring sites across Houston so that we can compare with previous studies and have good spatial coverage in the metroplex. Specifically, we will deploy our Mobile Air Quality Laboratory 2 (MAQL2) to conduct particle size, distribution and detailed composition, cloud condensation nuclei

cloud condensation nuclei

Tiny airborne particles suspended in the atmosphere that serve as the seeds around which cloud droplets form.

Source: Source

(CCN) concentration and activity, aerosol optical properties, gas and meteorology measurements at multiple sites across Houston. These detailed atmospheric chemistry measurements will be integrated with atmospheric modeling to evaluate how observed differences across Houston are related to emissions, aerosol processes and convective storm activity.

Project Objectives

1. Conduct aerosol (particle size, distribution and composition, CCN concentration and activity, aerosol optical properties), gas and meteorology measurements at satellite sites across Houston to complement and enhance measurements by the DOE during the TRACER campaign and make campaign data available to the TRACER scientific community to complement and enhance future modeling efforts.
2. Determine spatial variability across the Houston metropolitan area of aerosol characteristics in pre- and post-storm scenarios in terms of particle size, distribution, composition, CCN activity and optical properties.

optical properties

The characteristics of a material that define how it interacts with light.

Source: Source

3. Determine how urban aerosol processing differs between pre- and post-storm atmospheres in terms of particle growth, aging and CCN activity utilizing integration of observations and modeling.
4. Identify potential influences of convective transport (e.g. downdrafts) on particle size, number and composition through the interpretation of in situ and airborne chemical measurements.

Outcomes and Benefits

The TRACER-MAP datasets will provide key aerosol, gas and atmospheric measurements to assess the spatial heterogeneity of aerosol regimes across Houston, which can be utilized to answer science questions in the current project and by future DOE projects. The datasets will be shared publicly at the ARM Data

ARM data

Continuous field measurements of atmospheric data collected with Atmospheric Radiation Measurement (ARM) instruments at fixed and varying locations worldwide.

Source: Argonne National Laboratory Source

Center and will provide powerful information for understanding and modeling how aerosols interact with deep convection systems within urban areas.