Satellite observations of CO₂ from a highly elliptical orbit for studies of the Arctic and boreal carbon cycle

Abstract

Here we report on an observing system simulation experiment (OSSE) to compare the efficacy of near-infrared satellite observations of CO 2 from a highly elliptical orbit (HEO) and a low Earth orbit (LEO), for constraining Arctic and boreal CO 2 sources and sinks. The carbon cycle at these latitudes (~50-90°N) is primarily driven by the boreal forests, but increasing anthropogenic activity and the effects of climate change such as thawing of permafrost throughout this region could also have an important role in the coming years. A HEO enables quasi-geostationary observations of Earth's northern high latitudes, which are not observed from a geostationary orbit. The orbit and observing characteristics for the HEO mission are based on the Weather, Climate and Air quality (WCA) concept proposed for the Polar Communications and Weather (PCW) mission, while those for the LEO mission are based on the Greenhouse gases Observing Satellite (GOSAT). Two WCA instrument configurations were investigated. Adopting the Optimal configuration yielded an observation data set that gave annual Arctic and boreal regional terrestrial biospheric CO 2 flux uncertainties an average of 30% lower than those from GOSAT, while a smaller instrument configuration resulted in uncertainties averaging 20% lower than those from GOSAT. For either WCA instrument configuration, much greater reductions in uncertainty occur for spring, summer, and autumn than for winter, with Optimal flux uncertainties for June-August nearly 50% lower than from GOSAT. These findings demonstrate that CO 2 observations from HEO offer significant advantages over LEO for constraining CO 2 fluxes from the Arctic and boreal regions.

Detecting regional patterns of changing CO 2 flux in Alaska

“…However, GOSAT, Orbiting Carbon Observatory-2, and other satellites that rely on passive near-IR techniques for measuring total column CO 2 , including missions using highly elliptical orbits to obtain dense high-latitude sampling (22), require sunlight reflected from the Earth's surface and thus, return poor sample yield during the long, dark cold season. Even for cold season measurements, passive IR techniques are challenged by signals in large air masses because of high solar zenith angles.…”

PMIF v1.0: an inversion system to estimate the potential of satellite observations to monitor fossil fuel CO<sub>2</sub> emissions over the globe

“…Imaging from geostationary orbit (GEO) imagers like NASA's GeoCarb mission (O'Brien et al, 2016;Polonsky et al, 2014) could offer sampling during different periods 555 within a day to constrain the diurnal profile of emissions. Highly elliptical orbit (HEO) imagers could also provide observations at northern high latitudes with a similar high frequency as GEO (Nassar et al, 2014). However, even though multiple space-https://doi.org/10.5194/gmd-2019-326 Preprint.…”

Space‐Based Observations for Understanding Changes in the Arctic‐Boreal Zone

“…Mission enhancements were also considered to measure CO 2 , CH 4 , CO, O 3 , NO 2 , SO 2 , aerosols, temperature and water vapor (LaChance et al, ; McConnell et al, ). An OSSE demonstrated that the CO 2 observations from HEO would provide much improved constraints on ABZ terrestrial biospheric CO 2 fluxes relative to GOSAT (Nassar et al, ), especially during the summer months when the expected CO 2 fluxes (due to boreal forest growth or disturbances or permafrost thaw) and their uncertainties would both be largest. Other advantages, including the diurnal coverage available from HEO and imaging capability, were not assessed in the OSSE, but would contribute further information needed to reduce uncertainty in ABZ CO 2 and CH 4 fluxes.…”