Earth's albedo variations 1998-2014 as measured from ground-based earthshine observations

TL;DR

This study uses ground-based earthshine observations over sixteen years to analyze Earth's albedo variations, revealing two decadal cycles with no significant long-term change, and aligning well with satellite data.

Contribution

It provides a long-term ground-based measurement of Earth's albedo, identifying decadal cycles and validating satellite observations.

Findings

Two decadal cycles in Earth's albedo detected

No significant net change over 16 years

Earthshine measurements agree with CERES satellite data

Abstract

The Earth's albedo is a fundamental climate parameter for understanding the radiation budget of the atmosphere. It has been traditionally measured from space platforms, but also from the ground for sixteen years from Big Bear Solar Observatory by observing the Moon. The photometric ratio of the dark (earthshine) to the bright (moonshine) sides of the Moon is used to determine nightly anomalies in the terrestrial albedo, with the aim is of quantifying sustained monthly, annual and/or decadal changes. We find two modest decadal scale cycles in the albedo, but with no significant net change over the sixteen years of accumulated data. Within the evolution of the two cycles, we find periods of sustained annual increases, followed by comparable sustained decreases in albedo. The evolution of the earthshine albedo is in remarkable agreement with that from the CERES instruments, although each method measures different slices of the Earth's Bond albedo.