Research

Reconstruction of Earth’s past energy imbalance

(Poster AGU24)

Preliminary global-mean surface temperature reconstruction over 850-2000, expressed as anomalies relative to 1951-1980 with a 20-year lowpass filter. The thick black line is the ensemble median, the thinner lines are individual ensemble members, all of which are consistent with the proxies. The reconstruction, based on the PAGES2k proxy network, agrees well with instrumental products over the historical period. The corresponding top-of-atmosphere radiation is reconstructed based on the temperature using a climate model.

My current research focuses on reconstructing Earth’s energy imbalance and top-of-atmosphere radiation over the last millennium. We use climate model simulations with historical forcings and data assimilation of temperature-sensitive proxies. The proxies allow us to reconstruct past sea surface temperatures and sea ice cover, which are then prescribed as boundary conditions for ensemble simulations to diagnose forcings and feedbacks. We use this reconstruction to investigate mechanisms and patterns of multidecadal variability in Earth’s energy budget, which are poorly understood. We are also interested in forced trends of radiation at millennial timescales. 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.