A Summary of Early Surface Area Map Observations from the Orbiting Carbon Observatory-3

The Orbiting Carbon Observatory-3 (OCO-3) was launched on May 4, 2019, installed on the International Space Station (ISS) on May 10, and saw first light with cold detectors on June 26^th. While the core of OCO-3 matches the OCO-2 instrument, both the installation location on the ISS and an agile Pointing Mirror Assembly (PMA) allow observations that were not possible with OCO-2. The ability of the PMA to quickly repoint the field of regard of OCO-3 allows the creation of a Surface Area Map (SAM) that can cover an area of ~80km x 80km in approximately two minutes. These SAMs are made by using the PMA to create several parallel swaths over the area of interest. Additionally, since the PMA is a full two-axis pointing system, areas away from the ISS ground track may be routinely observed. This new mode allows mapping of a small region such as a city or providing regional context for specific locations.

The target list for OCO-3 includes Total Carbon Column Observing Network sites for validation, Collaborative Carbon Column Observing Network sites, cities with large fossil fuel emissions, Solar Induced Fluorescence (SIF) validation sites, and a few volcanos. The planning system can also accommodate new locations so that coordinated observations can be made with field campaigns of various sorts. Instrumental safety concerns, ISS-related near-field obstructions, and the precessing ISS orbits, however, combine to present significant challenges to scheduling and executing SAM observations. Here we present a summary of the SAMs acquired in the few months of the OCO-3. The distribution of the SAMs in space and time is shown, along with statistics of cloud-free scenes and other metrics of observational success. Example SAMs are shown along with instructions on how to locate and extract SAM data from specific times and places.