NASA’s Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission is set to launch in early 2024, with the aim of revolutionizing our understanding of Earth’s atmosphere and oceans. The mission will deploy advanced polarimeters to study the intricate dance between light, aerosols, and clouds, offering unprecedented insights into their impact on climate and air quality.
Aerosols are tiny airborne particles such as sea salt, smoke, dust, and pollutants that play a critical role in shaping our planet’s climate. They scatter and absorb sunlight, influencing how much solar energy reaches the Earth’s surfaceThey also affect cloud formation, weather patterns, and climate dynamics.
However, the complexity of their interactions with light has made it challenging for scientists to fully grasp their effects. Some aerosols have a cooling effect, while others have a warming effect. Some aerosols enhance cloud formation, while others suppress it. Some aerosols reflect light back to space, while others absorb it and heat the atmosphere.
How will PACE measure aerosols and clouds?
PACE will use two cutting-edge instruments, HARP2 and SPEXone, to measure the polarization of light — a property invisible to the naked eye but crucial for understanding the size, composition, and concentration of atmospheric particles.
HARP2, developed at the University of Maryland, will capture light across four wavelengths from up to 60 different angles. Its counterpart, SPEXone, crafted by the Netherlands Institute for Space Research (SRON) and Airbus Netherlands B.V., will focus on a narrower field with five viewing angles but will analyze light at hyperspectral resolution.
This duo promises to deliver a comprehensive view of our atmosphere with an accuracy never before achieved. They will be able to distinguish between different types of aerosols, such as dust, smoke, and pollution, and determine their optical properties, such as how much they scatter and absorb light.
They will also be able to measure the properties of clouds, such as their height, thickness, phase, and droplet size. These properties affect how clouds reflect and transmit light, as well as how they interact with aerosols.
What are the benefits of PACE for science and society?
The significance of PACE extends beyond scientific curiosity. The mission’s data will have practical applications, such as improving air quality forecasts and informing policy decisions.
Marcela Lora-Salazar, assistant professor at the University of Oklahoma and PACE early adopter, anticipates using PACE data to track aerosol changes over time and altitude, particularly over the central United States, to better understand their implications for air quality.
She said, “PACE will provide us with a unique opportunity to study the vertical distribution of aerosols, which is very important for air quality and health. We will be able to see how aerosols are transported by winds, how they mix with clouds, and how they affect the radiation budget of the Earth.”
PACE will also help scientists unravel the mysteries of Earth’s climate, by providing new insights into how aerosols and clouds affect the Earth’s energy balance and water cycle. These processes are essential for sustaining life on our planet, but they are also sensitive to changes in greenhouse gas concentrations, land use, and human activities.
PACE will complement other NASA missions, such as SWOT, which will measure Earth’s surface water with unprecedented detail and accuracy. Together, these missions will provide a holistic picture of how our oceans and atmosphere interact in a changing climate.