Satellite Observations of Earth's Energy Budget and Climate: Past, Present and Future (Invited Presentation)

This presentation provides a discussion about the evolution of Earth Radiation Budget (ERB) satellite observations and how they’ve contributed to our understanding of the climate system. Interest in Earth’s radiation budget dates back to the first half of the 19^th century, when scientists were interested in understanding long-term variations in climate. Unfortunately, these efforts were hindered by the lack of reliable information on some basic properties of the climate system, such as solar irradiance, planetary albedo, and outgoing thermal radiation. With the arrival of satellites in the late 1950s, instruments that could measure Earth’s heat budget were amongst the first flown alongside imagers intended for weather forecasting. This was soon followed by observations of the regional distribution of top-of-atmosphere (TOA) radiation budget, which enabled new insights on atmospheric and oceanic heat transport within the climate system. Further technological improvements in instrumentation allowed finer spatial resolution, which led to new insights about the critical and complex role clouds play in influencing the ERB and climate. To this day, the cloud response to climate forcing remains the largest uncertainty in model projections of future warming. Even basic questions about clouds, such as why they distribute themselves in such a way as to ensure there is hemispheric symmetry in albedo under all-sky conditions remains a mystery.

The hugely successful Earth Observing System (EOS) and A-Train constellation of satellites are providing unprecedented satellite records of key properties of the atmosphere and surface that influence ERB. These along with TOA ERB observations and improved reanalysis products can now be used to provide a more thorough observation-based understanding of Earth’s energy flows from the TOA down to surface over a range time-space scales. Importantly, the length of these records—which arguably surpassed anyone’s expectation—is enabling the climate analysis community with a wealth of new information with which to evaluate and constrain global climate models. Long-term stable climate data records of key climate parameters that influence the ERB are critically needed in order to adequately test models under a range of conditions and over relevant timescales owing to the substantial internal variability in the climate system. We present a recent example of unprecedented variations in the ERB observational record to highlight some key points and discuss future directions in ERB and climate research.