Colloquium: Gerard van Harten

    Tuesday, January 17, 2017 - 2:00pm
    Franken Conference Room (Meinel 821)

    Remote Sensing of Atmospheric Aerosols and Clouds Using High-Accuracy Polarimetry


    Ambient particulate matter is the largest global environmental risk factor, causing millions of premature deaths per year.  In addition, the direct interaction of aerosols with sunlight, and the indirect effect through their impact on cloud formation, represent the largest uncertainty in the Earth’s changing energy budget.  Both science cases impose an urgent need for global observations of the amount and spatial distribution of aerosols, the particle sizes and species.  These properties can be retrieved from multi-angle, multi-wavelength, radiometric and polarimetric observations of scattered sunlight.  One of the main challenges to date is the stringent requirement on the polarimetric accuracy of 0.005 in the degree of linear polarization.  I will discuss two novel polarimetric techniques (spectral polarization modulation and high-speed temporal modulation) that have proven to meet the accuracy requirement.  Ground-based and airborne instruments using these techniques (SPEX and MSPI, respectively) are currently in operation, and characterization of their polarimetric performance is ongoing.  This includes on-ground and in-flight calibration and validation, as well as comparisons of in-flight data from different instruments.  I will present aerosol measurements, and the first results of remote cloud droplet size measurements using AirMSPI in the recent ORACLES field campaign in Namibia.  Finally, I will talk about NASA/JPL’s future MAIA satellite instrument, based on the successful MSPI instruments and scheduled for launch around 2021, which will study the health effects of different aerosol species in large cities across the globe.

    Speaker Bio(s): 

    Dr. van Harten received his PhD in Astronomy, his MSc in Astronomy and Space Research and his B.S. in Physics and Astronomy from Leiden University, The Netherlands.  He is a researcher in remote sensing instrumentation, with expertise at the intersection of science and engineering. He is employed with Jet Propulsion Laboratory in Pasadena, CA.