Research

Reconstruction of Earth’s past energy imbalance

(Preprint, Poster AGU24, GitHub)

a Global-mean surface temperature reconstruction over 850–2000, expressed as anomalies relative to 1961–1990. Our reconstruction, based on proxies like tree rings and corals, agrees well with instrumental products over the historical period. The thick black line is the ensemble mean, the thinner lines are individual ensemble members, all of which are consistent with the proxies. b Our reconstruction of Earth's energy imbalance over the pre-industrial period provides context for the energy gain measured by satellites. The recent trend in energy gain exceeds anything that can be explained by natural variability, indicating a human influence.

My current research focuses on reconstructing Earth’s energy imbalance and top-of-atmosphere radiation over the last millennium. The energy imbalance is the most fundamental metric of climate change, yet our observational record is short and coupled climate models have large uncertainties. We extend the energy budget record based on proxies such as tree rings, corals, and ice cores. Our reconstruction reveals a cooling trend over the last millennium, accompanied by sustained energy loss and sea ice growth. The pre-industrial variability provides context for the recent energy gain, which we find to be unprecedented over 850–1850, indicating a human rather than natural cause. This work is advised by Greg Hakim.

High-accuracy radiation pressure models

(Paper, GitHub)

Ground track of LRO for one orbit, colored by the irradiance due to lunar albedo. This irradiance is calculated from the incident solar radiation and a spherical harmonics expansion of the albedo distribution. A spacecraft model then takes the direct solar and lunar albedo radiation to estimate the acceleration due to radiation pressure, resulting in small orbital perturbations.

For this work, we investigated the effect of radiation pressure on the Lunar Reconnaissance Orbiter (LRO). We compared models of varying complexity to determine the benefits and computational cost of high-accuracy radiation pressure modeling. These models are necessary for precision orbit determination, which is a prerequisite for LRO’s geodetic mission objectives. We implemented models for both the spacecraft and radiation sources in the Tudat numerical astrodynamics framework. We found that accurate spacecraft models are necessary to account properly for changing orientation and geometry, but complex lunar models have little benefit over simpler ones. This work was advised by Dominic Dirkx.