Mount Washington Icing Sensors Experiment (MWISP) 1999

Aircraft icing continues to plague commuter, military, and general aviation by causing fatal crashes, particularly in wintertime. Improved methods to forecast, detect, and avoid icing conditions are actively sought by the FAA, NASA, and other groups to improve flight safety. The Mount Washington Icing Sensors Project (MWISP) was a multi-agency experiment designed to assess some emerging icing detection technologies. It emphasized testing remote sensing methods for detecting, measuring, and mapping regions of supercooled liquid water in clouds and it assessed the amount of development needed to convert these research techniques into operationally useful tools.

The MWISP field project, centered at the Mount Washington Observatory (photo inset) in New Hampshire, in April 1999 included radars, radiometers, lidars, and in-situ cloud sampling instruments at the base of the mountain, at the Observatory, and onboard research aircraft. In collaboration with other participants, NOAA/ETL operated two Doppler radars and a tri-channel microwave radiometer at the base of the mountain and a multi-channel polarized scanning radiometer at the Observatory on the 6,288-foot summit. Depolarization measurements from the NOAA/K Ka-band radar provided information about hydrometeor types (crystals, droplets, etc.) in the mountain clouds. Microwave radiometers provided additional information about cloud composition along their beams.

NOAA K-band Radar

NOAA/K polarization measurements have demonstrated that, if the proper polarization basis is used, polarization data from a sensitive cloud radar can be used to provide a signature uniquely related to particle type.

Polarimetric Scanning Radiometer (PSR)

NOAA ETL participated in the 1999 Mount Washington Icing Sensors Project (MWISP99) by deploying the PSR/A scanhead in a ground-based configuration on the summit of Mt. Washington in New Hampshire. The purpose of MWISP99 was to obtain experimental signatures of supercooled liquid clouds viewed horizotnally using a foward-looking polarimetric radiometer under near-flight conditions. Such data is essential in developing aircraft sensors that can potentially detect aircraft icing conditions. The conditions at the Mt. Washington summit (elevation 6288', winds exceeding hurricane force (75 MPH) on an average of 104 days a year, and cloud shrouded about 60% of the time) are ideal for near-flight observations of supercooled liquid clouds.

During MWISP99 the PSR performed vertical range-height indicator (RHI) scans in an east-west plane using a field-of-view passing through both zenith and the westward horizon. Looking west, the PSR viewed over radar, radiometer, and lidar equipment located at the Mt. Washington Cog Railway Base site. A new sector-imaging scan mode was also implemented to obtain two-dimensional angular imagery of clouds as approaching from the west. The instrument operated successfully for over four weeks during this deployment.