The ASCENDS Approach

In order to better quantify, monitor and understand the Earth’s carbon cycle and its evolution in a changing climate, we need to develop and deploy improved remote sensing observation capabilities for atmospheric CO2. Existing services, such as GOSAT and OCO-2, utilise passive spectrometers which require sunlight and cloud-free conditions, making observations infrequent and subject to biases (e.g. due to the leakage of cloud scattered light into the signal). These limitations impact our understanding of the processes controlling the carbon cycle on regional and global scales.

In contrast, active CO2 remote sensing techniques allow accurate measurements to be taken day and night, over ocean and land surfaces, in the presence of thin or scattered clouds and throughout the year. The Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission was launched to take advantage of these benefits. The ability of ASCENDS to collect low-bias observations in these previously challenging conditions is expected to address important gaps in our knowledge of the carbon cycle.

The ASCENDS mission will take global atmospheric column CO2 measurements without a seasonal, latitudinal, or diurnal bias. The mission will also measure the ambient air pressure and temperature, providing a more comprehensive data point at each measurement. ASCENDS will enable the quantification of the current global spatial distribution of terrestrial and oceanic sources and sinks of CO2 with a weekly revisit frequency. This will provide the basis for future projections of CO2 sources and sinks through data-driven enhancements of Earth system process modelling.

Find out more about the ASCENDS mission here.