Cutting through the noise of CALIPSO to better understand the intricacy of aerosols within the atmosphere

This year’s Climate and Society class is out in the field (or lab or office) completing a summer internship or thesis. They’ll be documenting their experiences one blog post at a time. Read on to see what they’re up to.

Andrea MartinezC+S ’16

Clouds have a substantial role in stabilizing the surface temperature of Earth and regulating the global hydrological cycle. Aerosols are particulate matter that are suspended in the atmosphere either as a solid or liquid. Aerosols have numerous sources such as a volcanic eruption or burning biomass. When aerosols are released into the atmosphere through a natural or manmade source they influence cloud properties. Properties that are modified are atmospheric height, water phase, or brightness. These seemingly insignificant changes to cloud properties will have large implication for the global climate both to how clouds block and retain heat and also when and how much it rains. Understanding the origin and dispersion patterns of aerosols is imperative to understanding their true effect on climate change and doing so will allow decision-makers to improve policies regarding emitted aerosol pollutants.

CALIPSO obtains atmospheric features vertically using backscatter and depolarization values. Source: NASA

CALIPSO obtains atmospheric features vertically using backscatter and depolarization values. Source: NASA

One NASA satellite that is allowing us to improve our understanding of how aerosols interact in the atmosphere and influence ecosystem regulation is Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO). The satellite was launched in 2006 with the purpose of offering an alternative view of the interactions between aerosols and the climate by displaying vertical atmospheric features up to 30 kilometers above the Earth’s surface.

The CALIPSO satellite probes the atmosphere with a pulse laser. When the signal of the laser is returned to the satellite, it records the altitude and physical characteristics of each particle within the atmosphere. The returned light will have a different value depending on particle size and type. These values can then be used to classify atmospheric features. My work this summer at the NASA DEVELOP National Program has allowed me to build on this knowledge to create additional visual classification interfaces.

To create these interfaces, CALIPSO’s raw data array need to be converted to a multi-colored image. Since atmospheric features can be differentiated based on their size, the value returned to the satellite can then be used to classify a specific point in space. The vertical feature mask that was coded in Python this summer classifies each point as seven possible features and could be one of the following: clear air, cloud, aerosol, stratospheric layer, surface, subsurface, or totally attenuated. Another visualization feature that has been created is used to determine the water phase of clouds. This is done by looking at the ratio of returned satellite values. The closer the ratio is to one the more likely it is water and if the value is closer to zero then the point is most likely ice (figure 2).

The big questions are how can we take these new visualization features of CALIPSO data to improve understanding of the atmosphere and furthermore, how can this knowledge be applied to benefit society?

A new visualization feature that differentness clouds’ water phase. Source: NASA

A new visualization feature that differentness clouds’ water phase. Source: NASA

The vertical feature mask allows scientists to understand how aerosols are distributed in the atmosphere. They can determine what aerosols or pollutants are occurring in certain areas and provide a possible explanation of how they originated. Knowing where aerosols come from can help government make tighter restrictions or set other policies to limit their emissions. Monitoring the ice-water phase feature allows scientist to understand how aerosols are interacting with cloud properties and what this means for the hydrological cycle.

The launch of these satellites and improvements in technology has pushed the frontier of science, allowing us to enhance our understanding of ecosystem regulations and the intricacy of Earth as a single unit. With this knowledge we can observe how climate change is modifying key natural processes. It is through these new scientific insights that allow decision makers to implement more efficient and beneficial policies worldwide.

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