NLC detection and particle size determination: first results from SCIAMACHY on ENVISAT Original Research Article

Measurements of limb scattered radiance spectra performed with the SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY (SCIAMACHY) aboard ENVISAT are used to detect noctilucent clouds (NLCs) in the northern hemisphere during summer 2002. The NLCs are easily identified by enhanced limb radiances around 80 km tangent height. Using limb radiances in the UV-B/C spectral range, where multiple scattering is negligible, the spectral signature of the NLC backscatter can be determined directly. Mie-calculations are used to estimate particle sizes of these clouds from SCIAMACHY measurements. In particular, we use the information contained in the spectral exponent of the NLC limb backscatter signal. The derived particle radii assuming a log-normal NLC particle size distribution are 40–50 nm and they are in excellent agreement with previous particle size estimates.