bio blog talks projects
 

Current projects
Last update: December 2024

My core focus is on atmospheric gas and cloud composition, especially as tracers of atmospheric chemistry, climate, evolution, and origins.

I study planetary atmospheres using a wide range of techniques and facilities: remote sensing with ground-based and space telescopes like Keck and Hubble, the mass spectrometers on the Galileo Probe and Curiosity Mars Rover, and sensors on spacecraft missions like Juno. The projects described below take up the majority of my current research time, and lists of selected papers provide more detail on the types of questions being investigated.

Older pages list projects and science themes from previous updates in 2014 and 2016.

 

OPAL
G540, G480, G485, G527, G549, G551, G590

The Outer Planet Atmospheres Legacy program (OPAL) is a unique, solar system-focused example of the trend toward large programs at premier observatories. I am the UC Berkeley lead of this program, with PI Amy Simon at NASA Goddard.

OPAL maps each planet for two consecutive rotations, every year, using the Wide Field Camera 3 (WFC3) on Hubble. High-level science products are archived at a dedicated MAST page. So far OPAL data have ruled out a convective origin for 2014 cloud activity on Uranus, discovered new dark vortices on Neptune in 2015 and 2018, found evidence of new and rare atmospheric waves on Jupiter in 2015 and 2016, documented subtle photometric color changes in Saturn's bands in 2018-2020, found the Great Red Spot's winds to be speeding up even as the vortex shrinks, explained UV-dark ovals in Jupiter's polar stratosphere in terms of ionospheric momentum exchange, and quantified the seasonal change in the polar haze of Uranus. OPAL data have been used in coordinated studies with data from spacecraft (Voyager, Cassini, New Horizons, and Juno), ground-based telescopes from the smallest (globally-distributed amateurs) to the largest apertures (VLA, Keck, VLT, and Gemini), and Hubble's fellow space telescopes (JWST, Spitzer, and Kepler).

Please see the list of recognized publications using OPAL data to date.

IN SITU ATMOSPHERIC SAMPLING
G320, G525, G560, G610

My graduate career began with calibration and analysis of mass spectral data from the Galileo Probe's descent into Jupiter's atmosphere, which measured intriguing profiles of varaible volatile abundances. I was able to continue work with the Goddard mass spectrometer group to analyze atmospheric data from the SAM instrument suite on Mars Science Laboratory (Curiosity). Conducting in-situ composition measurements at Uranus might be possible within my lifetime, and I am interested in the development of miniaturized composition sensors that would allow measurements in a different area of the planet using a smaller secondary atmospheric probe, as described in the SNAP mission concept.

 

JUNO SCIENCE
G570, G480, G485, G550, G551

I led a series of HST and Gemini Observatory programs providing imaging context (near-UV, visible, infrared) for Juno's atmospheric science passes. After selection as a Participating Scientist, I collaborated with other team members on studies of Jupiter's spatially/temporally variable composition, cloud features, and dynamics and climate. A particular focus is on the study of Jovian lightning as a tracer of convective activity.

 

VORTEX STUDIES
G480, G512, G527, G549, G575

We conduct observations and simulations of giant planet vortices to understand their origin and evolution, and ultimately the structure of their atmospheric environments. Observables include horizontal wind field measurements at Jupiter (where we achieve high spatial resultion using space telescopes), long-term tracking from cadenced imaging, multispectral mapping to determine the vertical structure of aerosols, compositional and thermal retrievals from infrared and microwave spectra, and even gravitational perturbations from density anomalies. I have participated in studies of anticyclones (high-pressure systems) and cyclones (low-pressure systems prone to convective outbursts) on Jupiter and Saturn, and led programs to conduct the first evolutionary study covering the full lifetime of a dark spot on Neptune from origin to dissipation.

 

DYNAMICAL SIMULATIONS
G600, G480, G527

I work closely with fluid modelers to test interpretations of observational results related to anticyclones from Jupiter's Great Red Spot to the dark spots on Neptune. Current studies with Ramana Sankar and Csaba Palotai are focused on understanding the spatially-variable moist convection in Jupiter's atmosphere on a global basis.

     

 

GAS GIANT THERMAL RADIATION
G526, G575, G546, G549, G470, G570

Thermal infrared and radio wavelength light from Jupiter and Saturn, heat energy that is radiatively escaping from the planet, carries with it information about the 3D spatial distribution of volatile gases ammonia and water, temperature, and cloud material. Microwave maps from the VLA and Juno reveal intricately detailed bright and dark patterns at different wavelengths, modulated by both temperature and the amount of ammonia gas present. Ammonia acts as a tracer of vertical motions, so the brightness patterns trace motions driven by convection, waves, jets, and turbulence. In the 5-micron window within these planets' spectra, high-resolution spectrometers (NASA IRTF, Keck, and JWST) sense variations in volatile and disequlibrium gases, as well as aerosols. The correspondence between microwave and 5-micron maps shows that cloud density and ammonia concentration have highly correlated variability as a result of vertical flows.