New Insights into Tropical Cyclone Dynamics from the MISR Instrument on NASA's Terra Satellite

By late February 2012, the Multi-angle Imaging SpectroRadiometer (MISR) instrument will have been operational on the polar orbiting Terra satellite for 12 years. During this period, MISR has observed a number of tropical cyclones in various stages of development. With nine cameras that acquire imagery in visible and near-infrared channels at up to 275 m spatial resolution over a period of seven minutes, MISR provides unique, detailed information on cloud-top heights and cloud-track winds in the complex and dynamically evolving tropical cyclone environment.

We will describe three new avenues of research using MISR to study tropical cyclones. First, we will discuss mesoscale dynamics captured by the enhanced height-resolved cloud motion vectors produced operationally at 17.6 km spatial resolution and experimentally at still higher spatial resolutions. These wind vectors provide insight into the circulation at both low and high levels within tropical cyclones. Next, we will show how very high resolution cross-track wind speeds reported every 1.1 km provide quantitative estimates of cloud-top divergence and associated vertical velocities at the top of rapidly developing systems. These features are clearly associated with vortical hot towers and changes to system intensity. Finally, we will describe comparisons between MISR stereo-derived cloud top heights and cloud top temperatures obtained from the MODIS instrument also on the Terra satellite. Similarities and difference between these two measurements will be discussed, including what this reveals about the environment at the tops of the highest clouds in tropical cyclones.