Tangent height registration method for the Version 1.4 data retrieval algorithm of the solar occultation sensor ILAS-II

• Published in: Applied optics (2004) Vol. 46; no. 29; p. 7196
• Main Authors: Tanaka, Tomoaki, Nakajima, Hideaki, Sugita, Takafumi, Ejiri, Mitsumu K, Irie, Hitoshi, Saitoh, Naoko, Terao, Yukio, Kawasaki, Hiroyuki, Usami, Masatoshi, Yokota, Tatsuya, Kobayashi, Hirokazu, Sasano, Yasuhiro
• Format: Journal Article
• Language: English
• Published: United States 10.10.2007
• ISSN: 1559-128X
• DOI: 10.1364/ao.46.007196

The Improved Limb Atmospheric Spectrometer-II (ILAS-II) is a satellite-borne solar occultation sensor onboard the Advanced Earth Observing Satellite-II (ADEOS-II). The ILAS-II succeeded the ILAS. The ILAS-II used four grating spectrometers to observe vertical profiles of gas volume mixing ratios of trace constituents and was also equipped with a Sun-edge sensor to determine tangent heights geometrically with high precision. The accuracy of gas volume mixing ratios depends on the accuracy of the tangent height determination. The combination method is a tangent height registration method that was developed to give appropriate tangent heights for the ILAS-II Version 1.4 data retrieval algorithm. This study describes the method used in the ILAS-II Version 1.4 retrieval algorithm to register tangent heights. The root-sum-square total random error is estimated to be 30 m, and the total systematic error is 180 m at an altitude of 30 km. The influence of the tangent height errors on the vertical profiles of gas volume mixing ratios in ILAS-II Version 1.4 is estimated by using the relative difference. The relative difference for each species is within 7% (20%) for an altitude shift of +/-100 m(+/-300 m).