About THOR

Thor is an airborne lidar instrument designed to measure the thickness and internal structure of highly scattering media such as thick clouds, snow, or sea ice. It is a multi-view lidar system: It emits short laser pulses and observes both the spatial and temporal characteristics of the pulses spreading inside the probed media.


Setup of typical THOR cloud observations

THOR sends short green laser pulses into the cloud and counts the photons that return directly from the illuminated spot and from seven concentric circles surrounding it.



  • Cloud thickness retrievals have been validated during flights over stratus clouds in Oklahoma.
  • Snow and sea ice thickness retrievals are expected once planned upgrades will allow THOR to resolve the small bright halos that surround the illuminated spot in snow and sea ice.


The THOR team

Last updated:
November 2, 2011.
Web site contact: Tamás Várnai
Project contact: Robert Cahalan
Return to Climate Home Climate and Radiation Branch Homepage NASA Homepage NASA Goddard Space Flight Center Homepage Lab for Atmospheres Homepage