What is PACE going to measure?Photos of Earth taken from space show vast blue seas and stretches of white clouds. Looking more closely and beyond what we can see by eye reveals important details about our living ocean and climate.
In orbit, PACE will measure light emitted by Earth, or its "radiance," at the top of the atmosphere. This signal will include everything below it; thus, scientists will need to separate contributions from the atmosphere and ocean.
Being located farther from the satellite, only a small fraction of light will come from the ocean. Subtracting the signal of the atmosphere helps to determine a key value, "water-leaving radiance." This can be used to learn more about microscopic algae (phytoplankton) at the ocean surface. How? Phytoplankton have various shapes, sizes, and pigments; all of which affect ocean color. To help decipher phytoplankton types, PACE will sense color at very high resolution and over a broad spectrum: from ultraviolet to infrared wavelengths.
Color is not the only property of light that tells us about our planet. Light's polarization how it oscillates within a geometric plane is another important dimension of information. For example, when sunlight interacts with clouds or aerosols, its polarization can change. Measuring these types of changes will help us better understand our atmosphere and climate.
PACE by Wavelength »
Phytoplankton Exploration (Phytopia) »
Science Investigation Team & Meeting Archives »
Satellite Remote Sensing: Ocean Color (Werdell & McClain, 2019) »
How will it work?PACE's primary sensor is the Ocean Color Instrument (OCI). Its unprecedented coverage of broad wavelengths at high resolution will not only benefit ocean science but atmospheric science, as well. OCI data will be complemented by measurements from two polarimeters being planned for PACE. These instruments will focus on the study of clouds and aerosols.
Collectively, these instruments are being designed to:
- Maximize information that can be derived such as phytoplankton types, clouds, and aerosols; and
- Minimize artifacts such as sun glint and data striping.