The radiation characteristics of clouds are important factors in understanding the Earth's climate. Cloud properties in the infrared region have not previously been well measured from space. The quantum-well cloud sensor (QCS) is an innovative spaceborne instrument for imaging clouds and measuring their thermal brightness and bi-directional reflectance in selected long wavelength spectral bands. It also provides stereo viewing of clouds for altitude measurements. The QCS utilizes a GaAs, quantum-well, infrared photodetector (QUIP) array. This detector array has extremely good pixel-to-pixel uniformity and negligible i/f noise, which is important for future geostationary sensors that will use long signal integration times to compensate for their narrow field of views. In contrast to doped-silicon and HgCdTe arrays which are expensive, difficult to produce, and low yielding, the QUIP arrays promise to be more easily and uniformly producible and significantly less expensive. The anticipated results of Phase I are a feasibility analysis and a conceptual design for a complete instrument which could be built in Phase II and flown on a get-away special on the shuttle.
Potential Commercial Applications: Due to the lower manufacturing cost and negligible i/f noise of the QUIP detector array, the quantum-well cloud sensor is intended to be the forerunner of a line of commercial mid- and long-wavelength sensors..
