Performance of a geostationary mission, geoCARB, to measure CO<sub>2</sub>, CH<sub>4</sub> and CO column-averaged concentrations

Abstract

GeoCARB is a proposed instrument to measure column averaged concentrations of CO₂, CH₄ and CO from geostationary orbit using reflected sunlight in near-infrared absorption bands of the gases. The scanning options, spectral channels and noise characteristics of geoCARB and two descope options are described. The accuracy of concentrations from geoCARB data is investigated using end-to-end retrievals; spectra at the top of the atmosphere in the geoCARB bands are simulated with realistic trace gas profiles, meteorology, aerosol, cloud and surface properties, and then the concentrations of CO₂, CH₄ and CO are estimated from the spectra after addition of noise characteristic of geoCARB. The sensitivity of the algorithm to aerosol, the prior distributions assumed for the gases and the meteorology are investigated. The contiguous spatial sampling and fine temporal resolution that geoCARB could provide opens the possibility of monitoring localised sources such as power plants. Simulations of emissions from a power plant with a gaussian plume are conducted to assess the accuracy with which the emission strength may be recovered from geoCARB spectra. Scenarios for "clean" and "dirty" power plants are examined. It is found that a reliable estimate of the emission rate is possible, especially for power plants that have particulate filters, by averaging multiple snap-shots of the CO₂ field surrounding the plant. The result holds even in the presence of partial cloud cover

Simulating estimation of California fossil fuel and biosphere carbon dioxide exchanges combining in situ tower and satellite column observations

“…We note that OCO‐2 provides coverage for some regions that are not effectively sampled by towers, likely allowing detection of spatial patterns due to management or climate change mitigation strategies that are not accurately captured in models for biosphere CO 2 exchange. In this respect, future missions such as OCO‐3 on the International Space Station, and a recently selected geostationary satellite over the Americas (GeoCARB), offer the potential to improve spatial coverage of the California and the continental U.S. [ Polonsky et al , ].…”

Assessing the capability of different satellite observing configurations to resolve the distribution of methane emissions at kilometer scales

“…The TROPOMI instrument (Veefkind et al, 2012;Butz et al, 2012;Hu et al, 2016Hu et al, , 2018, launched in October 2017, will provide global mapping at 7 × 7 km 2 nadir resolution once per day. The GeoCARB geostationary instrument (Polonsky et al, 2014;O'Brien et al, 2016) will be launched in the early 2020s with current design values of 3 × 3 km 2 pixel resolution and twice-daily return time. Additional instruments are presently in the proposal stage with improved combinations of pixel resolution, return time, and instrument precision (Fishman et al, 2012;Butz et al, 2015;Xi et al, 2015).…”

Estimator of Surface Ozone Using Formaldehyde and Carbon Monoxide Concentrations Over the Eastern United States in Summer

“…We therefore use the model simulated data, which reasonably captures the observed aircraft concentrations and relationships of O 3 , CO, and CH 2 O during the DISCOVER‐AQ campaign, to develop and evaluate a surface O 3 estimation model with surface CO and CH 2 O as input parameters. In the future, geostationary satellite instruments such as Tropospheric Emissions: Monitoring of Pollution (TEMPO; Chance et al, ) and Geostationary Carbon Observatory (Polonsky et al, ) will greatly improve the monitoring of near‐surface measurements of O 3 precursors with sufficient accuracy and therefore make it possible to use observed CH 2 O and CO in the O 3 estimator we develop here. We describe the 3‐D chemical transport model, DISCOVER‐AQ data set, analysis methods, the O 3 estimation model, and validation method in section 2.…”