Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 6 3 2006 10.5194/acpd-6-4973-2006 http://www.atmos-chem-phys-discuss.net/6/4973/2006/ http://www.atmos-chem-phys-discuss.net/6/4973/2006/acpd-6-4973-2006.html http://www.atmos-chem-phys-discuss.net/6/4973/2006/acpd-6-4973-2006.pdf 4973 4994 2006-06-20 Validation of remotely sensed profiles of atmospheric state variables: strategies and terminology T. von Clarmann Forschungszentrum Karlsruhe, Institut für Meteorologie und Klimaforschung, Karlsruhe, Germany This technical note summarizes and classifies the various approaches to validation of remote measurements of atmospheric state variables, and tries to recommend a clear and unambiguous terminology. The following approaches have been identified: Intercomparison of single profiles for accuracy validation; statistical comparison of matched pairs of measurements with respect to bias determination and precision validation; statistical intercomparison of randomly sampled measurements by two instruments, and comparison of a single measurement to an ensemble of measurements. Applicable statistics are shortly reviewed, and recipes for evaluation of the co-incidence error due to less than perfect co-incidences are presented. A rigorous approach is suggested to quantitatively validate profile measurements when full covariance matrices are unavailable. We distinguish between ''necessary validation'' which is rejection of the null hypothesis that a difference between two measurements is significant, and ''sufficient validation'' which means to provide evidence that the probability that there is a significant difference is definitely small.