<title>Novel spectrograph/radiometer for cloud top height measurement using three complementary techniques</title>

A proof-of-concept (POC) instrument system to measure cloud top height from space using three complementary techniques is presented. These techniques use measurements of (1) thermal infrared (IR), (2) molecular oxygen 'A' band absorption, and (3) filling-in of Fraunhofer lines (the Ring effect), respectively. Combining three techniques is achieved with a single grating spectrograph with bandpass and order sorting filters by measuring 11 micrometer radiation from the zeroth order of the grating for the IR, 750 - 780 nm radiation from the first order for the 'A' band absorption, and 390 - 400 nm radiation from the second order for the Ca K and H Fraunhofer line filling-in effect. The POC system and its measurement results with the POC system are described.