Selected Publications

The intrinsic spectral dimensionality indicates the observable degrees of freedom in Earth’s solar-reflected light field, quantifying the diversity of spectral content accessible by visible and infrared remote sensing. To date there has been no systematic study of its spectral dimensionality as a function of space, time, and land cover. Here we report a multi-site, multi-year statistical survey by NASA’s “Classic” Airborne Visible Near InfraRed Spectrometer (AVIRIS-C). AVIRIS-C measured large regions of California, USA, spanning wide latitudinal and elevation gradients containing all canonical MODIS land cover types.
Optics Epxress, 2017

Fugitive methane emissions are thought to often exhibit a heavy-tail distribution (more high-emission sources than expected in a normal distribution), and thus efficient mitigation is possible if we locate the strongest emitters. Here we demonstrate airborne remote measurements of methane plumes at 1- to 3-m ground resolution over the Four Corners region. We identified more than 250 point sources, whose emissions followed a heavy-tail lognormal distribution, a heavy-tail characteristic.
PNAS 113(35), 2016

Atmospheric correction of visible/infrared spectra traditionally involves either physics-based methods using Radiative Transfer Models (RTMs), or empirical methods using in situ measurements. Here a more general probabilistic formulation unifies the approaches. We incorporate reference measurements via Bayesian inference, leading to a Maximum A Posteriori estimate which is generally more accurate than pure physics-based methods yet more stable than pure empirical methods.
Optics Express 24(3), 2016

Shortwave Infrared spectroscopy can map cloud thermodynamic phase, which impacts clouds’ radiative forcing, evolution, and lifetime. This work: (1) proposes an accurate spectroscopic method for remote cloud phase mapping; (2) grounds it in radiative transfer simulations; and (3) validates it using field data with in-situ cloud particle measurements from the 2015 Calwater- 2 / ACAPEX campaign.
JGR Atmospheres 121(15), 2016

The Aliso Canyon gas storage facility near Porter Ranch CA produced a large accidental CH4 release from October 2015 to February 2016. The Hyperion imaging spectrometer onboard the EO-1 satellite successfully detected this event, achieving the first orbital detection of a CH4 super-emitter plume.
GRL 43(12), 2016

The San Francisco Bay–Delta Estuary watershed is a major source of freshwater for California and a profoundly human-impacted environment. Here, we show how the latest technology in visible/near-infrared imaging spectroscopy can facilitate water quality monitoring in this highly dynamic and heterogeneous system by enabling simultaneous depictions of several water quality indicators at very high spatial resolution.
Environ. Sci. Tech. 50(2), 2016

Small spacecraft platforms can address many of the the space community’s interests in origin science, planetary resources, and planetary defense. Such missions will likely require onboard data analysis to detect sources directly, or downlink parsimonious summary products for detection on the ground. Image credit: Neascout mission, NASA.
Proc. Astron. Soc. Pacific 127, 2015

The next Mars rover mission will deploy PIXL, the Planetary Instrument for X-Ray Lithochemistry, to analyze rocks' elemental compositions at high spatial resolution. The large data volumes require new approaches and algorithms for X-Ray fluorescence spectrum analysis. Image credit: NASA.
Astrobiology 15(11), 2015

This work explores theoretical foundations for automating in situ validation of remote sensing measurements. We focus on highdimensional sensor data with a specific case study of spectroscopic mapping. A field robot refines an orbital image by measuring the surface at many wavelengths. We introduce a new objective function based on spectral unmixing that seeks pure spectral signatures to accurately model diluted remote signals.
AAAI 2015

Recent Publications

  • A Large Airborne Survey of Earth’s Visible-Infrared Spectral Dimensionality

    Details PDF

  • Airborne methane remote measurements reveal heavy-tail flux distribution in Four Corners region

    Details PDF

  • Atmospheric Correction with the Bayesian Empirical Line

    Details PDF

  • Measuring cloud thermodynamic phase with shortwave infrared imaging spectroscopy

    Details PDF

  • Space-based remote imaging spectroscopy of the Aliso Canyon CH4 superemitter

    Details PDF

  • High-resolution remote sensing of water quality in the San Francisco Bay-Delta Estuary

    Details PDF

  • Autonomous Onboard Point Source Detection by Small Exploration Spacecraft

    Details PDF

  • Automating X-ray Fluorescence Analysis for Rapid Astrobiology Surveys

    Details PDF

  • Spatio-spectral exploration combining in situ and remote measurements

    Details PDF