He has 18 years of experience in radiative transfer modeling with application to remote sensing of Earth and (exo)planetary atmospheres. He leads several projects on using innovative radiative transfer techniques to retrieve atmospheric reactive and greenhouse gases and surface reflectance, understand aerosol vertical distribution, profile temperature and water vapor in the planetary boundary layer and improve diagnosis of clouds in climate models. These efforts are directly related to important missions recommended by the 2017 Earth Science Decadal Survey. In addition, he leads a project to utilize measurements of Earth's sunlit disk from Lagrangian orbit to model the Earth as a proxy exoplanet.