Ozone differential absorption lidar algorithm intercomparison


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gathen [ at ] awi-potsdam.de

Abstract

An intercomparison of ozone differential absorption lidar algorithms was performed in 1996within the framework of the Network for the Detection of Stratospheric Changes (NDSC) lidarworking group. The objective of this research was mainly to test the differentiating techniquesused by the various lidar teams involved in the NDSC for the calculation of the ozone numberdensity from the lidar signals. The exercise consisted of processing synthetic lidar signalscomputed from simple Rayleigh scattering and three initial ozone profiles. Two of these profilescontained perturbations in the low and the high stratosphere to test the vertical resolution of thevarious algorithms. For the unperturbed profiles the results of the simulations show thecorrect behavior of the lidar processing methods in the low and the middle stratosphere withbiases of less than 1% with respect to the initial profile to as high as 30 km in most cases. In theupper stratosphere, significant biases reaching 10% at 45 km for most of the algorithms areobtained. This bias is due to the decrease in the signal-to-noise ratio with altitude, which makes itnecessary to increase the number of points of the derivative low-pass filter used for dataprocessing. As a consequence the response of the various retrieval algorithms to perturbations inthe ozone profile is much better in the lower stratosphere than in the higher range. These resultsshow the necessity of limiting the vertical smoothing in the ozone lidar retrieval algorithm andquestions the ability of current lidar systems to detect long-term ozone trends above 40 km.Otherwise the simulations show in general a correct estimation of the ozone profile random errorand, as shown by the tests involving the perturbed ozone profiles, some inconsistency in theestimation of the vertical resolution among the lidar teams involved in this experiment.



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ISI/Scopus peer-reviewed
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Published
Eprint ID
987
Cite as
Godin, S. , Carswell, A. I. , Donovan, D. P. , Claude, H. , Steinbrecht, W. , McDermid, I. S. , McGee, T. J. , Gross, M. R. , Nakane, H. , Swart, D. P. J. , Bergwerff, H. B. , Uchino, O. , von der Gathen, P. and Neuber, R. (1999): Ozone differential absorption lidar algorithm intercomparison , Applied Optics, 38 (30), pp. 6225-6236 .


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