CPF Secondary NavigationCPF’s Science Goals
The CLARREO Pathfinder (CPF) mission has been designed to take shortwave (visible and near-infrared) measurements with sufficiently high accuracy such that they have the ability to more rapidly detect long-term trends than we can currently [Wielicki et al., 2013]. To address this critical need, CPF will strive to meet its two mission objectives: (1) To demonstrate on-orbit, SI-traceable calibration in measuring spectral reflectance (350-2300 nm), achieving an advancement in accuracy (by 5-10x) over existing sensors [Kopp et al., 2017]; and (2) To demonstrate the ability to use that unparalleled accuracy to serve as an on-orbit reference spectrometer for inter-calibration of other reflected solar satellite sensors [Lukashin et al., 2013]. CPF will demonstrate inter-calibration with two other Earth-observing instruments: (1) Clouds and the Earth’s Radiant Energy System (CERES); and (2) Visible-Infrared Imaging Radiometer Suite (VIIRS), on either the Suomi-NPP or NOAA-20 satellites.
Unparalleled Accuracy
The spectral range of HySICS (350 – 2300 nm) includes over 95% of the solar radiation reflected by the Earth. Energy within this spectral range drives critical processes including radiative forcing, the Earth system’s response, and critical geophysical feedbacks that modify how the sensitive the Earth system is to changes in greenhouse gas pollution. This is why detailed knowledge of the instrument’s calibration accuracy and how it changes in orbit is essential for observing the long-term trends of essential geophysical variables that drive and respond to the variability of the Earth system. Another key benefit from CLARREO Pathfinder measurements is the high amount of information provided by the continuous spectral sampling of 3 nm across its spectral range.
Measurements from a hyperspectral imager like HySICS are typically formatted in what is called a data cube (see the image below). The top face of the cube is a representation of the spatial scene, usually a red-green-blue (RGB) composite similar to a picture taken using a digital camera. But unlike a digital camera or even a typical space-borne imager that acquire measurements at just a few wavelengths, the CLARREO Pathfinder hyperspectral imager makes measurements at several hundred contiguous (neighboring) wavelengths that span most of the solar spectrum. The different wavelengths are represented by a third dimension, making a cube, such as the one below. Peeling off successive “layers” of the cube would reveal images of …