Mesoscale systems and dynamics revealed by MISR high-resolution, height-resolved, cloud-track winds and cloud-top heights

For over 11 years the Multi-angle Imaging SpectroRadiometer (MISR) instrument has been making global observations from NASA's polar orbiting Terra satellite. MISR's nine cameras acquire visible and near-infrared imagery with a temporal separation of approximately 50 seconds between cameras, at up to 275 m spatial resolution, over a span of seven minutes. By way of comparison a Geostationary Operational Environmental Satellite (GOES) in Super Rapid Scan Operations (SRSO) mode is capable of acquiring imagery with a time resolution of 60 seconds at up to 1,000 m spatial resolution. MISR provides multiangular information with temporal and spatial detail presently unavailable from any other satellite instrument.

Using multiple cameras, a stereo technique that tracks contrast features is employed to retrieve the height and one component of the motion of clouds at spatial resolutions up to 1.1 km. The height-resolved, full vector wind can also be retrieved within 17.6 km domains. The assignment of cloud top height is purely geometric, with a nominal vertical resolution of better than 500 m, and does not depend on ancillary knowledge of the thermal structure of the atmosphere or the absolute radiometric calibration of the instrument. These characteristics make MISR observations valuable in a variety of environments that are challenging for conventional remote sensing techniques, such as those based on the thermal infrared.

We will discuss MISR observations of mesoscale systems ranging from marine stratocumulus, where MISR provides accurate cloud-top heights in the presence of strong thermal inversions, to hurricane eyewalls. The height-resolved cloud-track winds from MISR provide further information on the dynamics of these mesoscale systems including estimates of the local divergence, which may provide insight into the vertical velocities associated with clouds in different environments. Comparisons will be shown with complementary observations, including other satellite and in situ data where available.