Houston Precipitation Experiment

The MODIS Airborne Simulator (MAS) is an airborne multispectral spectrometer that simulates the Moderate-Resolution Imaging Spectrometer (MODIS) satellite instrument. MAS operates over 50 spectral channels spanning 0.55 to 14.2 μm, producing high-resolution images of clouds and surface features. It has a horizontal spatial resolution of 50 meters and a swath width of about 36 kilometers at an altitude of 20 km at nadir. Its scan rate is 6.25 Hz, with each scan line containing 716 pixels.

The ER-2 Doppler Radar (EDOP) is an airborne X-band radar mounted on the nose of the ER-2 aircraft. It measures radar reflectivity, Doppler velocity, and spectrum width to characterize precipitation systems. EDOP operates at 9.6 GHz and provides data at 2 Hz. It has a typical gate spacing of 75 m and a beamwidth of 2.9 degrees. EDOP has since been replaced by the EXRAD radar.

The Scanning High-resolution Interferometer Sounder (S-HIS) is an airborne cross-track scanning interferometer developed by the Space Science and Engineering Center at the University of Wisconsin-Madison. It measures emitted thermal radiation between 3.3 and 18 microns with high spectral resolution. These measurements are used to derive atmospheric profiles of temperature and water vapor under clear-sky conditions. S-HIS has a spatial resolution of 2 km and a swath width of 40 km at an altitude of 20 km at nadir. It operates at a sampling frequency of 0.5 seconds and has an absolute radiance accuracy of 0.2 K.