Carbon-I, a NASA Earth System Explorer Mission concept for Greenhouse Gas Observations

The past two decades have seen tremendous improvements in greenhouse gas (GHG) remote sensing from space, including global area flux mappers like SCIAMACHY, GOSAT, OCO-2, GOSAT-2, TROPOMI and OCO-3 among others, with more missions planned, such as CO2M. In the past decade there has also been an increase in GHG point source imagers, a field that has grown rapidly after initial successes using AVIRIS-NG and subsequent VSWIR spectrometers (coarser spectral resolution over a broader range). While area flux mapper missions have been effective at measuring GHG with high accuracy, fundamental gaps persist in the humid tropics, where data yields are 2-3 orders of magnitude lower than elsewhere.

 

Here, we discuss the Carbon Investigation (Carbon-I), which was selected for a Phase A mission concept study within NASA’s Earth System Explorer call. Carbon-I provides a unique combination of global land coverage, high spatial resolution, and very high sensitivity required to quantify CH₄, CO₂, and CO emissions at both the area and point source scale. Given the importance of the tropics for global carbon budgets and in particular natural methane emissions, Carbon-I specifically targets the remaining data and knowledge gaps within the tropics, enabling a step change in our capabilities of observing the tropics with more even temporal and spatial sampling.

Carbon-I is a single-band spectrometer covering the 2040 to 2380 nm spectral range with 0.7nm spectral sampling and spatial sampling ranging from ~30m in a local target mode to ~300m for global land mapping. We will discuss the sweet spot in the tradeoff between spatial and spectral resolution, the multi-species trace gas capabilities (CH₄, CO₂, CO, HDO, H₂O, N₂O, potentially Ethane), the capabilities to measure GHG area fluxes and point sources while minimizing surface interferences and our approach to account for atmospheric scattering effects.