Determination of global Earth outgoing radiation at high temporal resolution using a theoretical constellation of satellites

Abstract

New, viable, and sustainable observation strategies from a constellation of satellites have attracted great attention across many scientific communities. Yet the potential for monitoring global Earth outgoing radiation using such a strategy has not been explored. To evaluate the potential of such a constellation concept and to investigate the configuration requirement for measuring radiation at a time resolution sufficient to resolve the diurnal cycle for weather and climate studies, we have developed a new recovery method and conducted a series of simulation experiments. Using idealized wide field‐of‐view broadband radiometers as an example, we find that a baseline constellation of 36 satellites can monitor global Earth outgoing radiation reliably to a spatial resolution of 1000 km at an hourly time scale. The error in recovered daily global mean irradiance is 0.16 W m−2 and −0.13 W m−2, and the estimated uncertainty in recovered hourly global mean irradiance from this day is 0.45 W m−2 and 0.15 W m−2, in the shortwave and longwave spectral regions, respectively. Sensitivity tests show that addressing instrument‐related issues that lead to systematic measurement error remains of central importance to achieving similar accuracies in reality. The presented error statistics therefore likely represent the lower bounds of what could currently be achieved with the constellation approach, but this study demonstrates the promise of an unprecedented sampling capability for better observing the Earth's radiation budget.

Remote sensing of earth’s energy budget: synthesis and review

“…Constellation of satellites may be a way to improve the estimation accuracy. Based on idealized simulations, Gristey et al (2017) determined that a baseline constellation of 36 satellites is needed to estimate the global daily mean reflected solar radiation and OLR with the error of 0.16 Wm −2 and −0.13 Wm −2 . In fact, the constellation of small satellites for the EEB has been recently proposed (Meftah, Keckhut, et al 2018), but more urgent studies are needed on virtual constellation, 'a coordinated set of space and/or ground segment capabilities from different partners that focuses on observing a particular parameter or set of parameters of the Earth system' as defined by the Committee of Earth Observation Satellite (CEOS) (https://agupubs.onlinelibrary.wiley.com/ doi/full/10.1002/2017EF000627).…”

Earth’s Energy Imbalance Measured From Space

“…This future study will show whether more satellites are needed to resolve the mean diurnal cycle of EEI adequately and if interpolation techniques can help reduce sampling errors. A study by [84] found that a constellation of 36 satellites is needed to estimate global daily mean shortwave and longwave outgoing radiation to within 0.16 Wm -2 and -0.13 Wm -2 . Given that we aim at longer-term estimates of annual or potentially monthly resolution, a less dense coverage is likely sufficient.…”

RAVAN: CubeSat Demonstration for Multi-Point Earth Radiation Budget Measurements

“…In either case, radiometers with and without filters blocking thermal wavelengths are used to distinguish the shortwave (SW) solar-reflected and longwave (LW) terrestrial emission components of the upwelling flux. The WFOV nonscanners are essentially single-pixel sensors and thus are unable to resolve radiance spatial variation within an individual FOV natively, although spatial information may be reconstructed from time series measurements along the orbit track [12–14]. In contrast, the NFOV instruments scan the visible Earth disk with FOVs of about 10–100 km, with varying viewing geometries.…”