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All figures (14)
Fig. 5. The percentage difference between the OEM retrieval and the ozonesonde measurements (blue curve) is plotted within the total statistical uncertainty of the OEM retrievals plus the ozonesonde measurement (red curves).
Fig. 6. Uncertainty budget on the night of 12 July 2017. The statistical uncertainty of the retrieval (blue), the Rayleigh-scatter cross section uncertainty at 308 nm (dashed line red), the Rayleigh-scatter cross section uncertainty at 289 nm (dashed line yellow), the ozone absorption cross section at 308 nm (dashed line purple), the ozone absorption cross section for the 289 nm channel (dashed line green), and the overlap function for the 289 nm channel (dashed line light blue) all contribute to the budget. The horizontal dashed line shows the height below which the retrieval is independent of the a priori profile.
Fig. 11. Left panel: The statistical uncertainty of the OEM retrieval (red curve) as well as the statistical uncertainty of the traditional retrieval (blue curve) for 12 July 2017. Right panel: Vertical resolution of the OEM retrieval is shown in red, while the vertical resolution of the traditional retrieval is shown in blue. The spike at 5.5 km in the OEM uncertainty is from the inclusion of the digital channels at this height.
Fig. 12. For the nights of 14 July and 26 July 2017, the tropospheric OEM retrieval is shown in red, the traditional retrieval is in blue, and the ozonesonde profile is in green. The horizontal dashed line is the “cut-off” altitude below which the OEM retrieval is mostly independent of the a priori ozone profile assumed. Left panel: retrievals for 14 July 2017. Right panel: retrievals for 26 July 2017.
Table 1. Values and associated uncertainties for the retrieved and forward model parameters.
Fig. 4. Left panel: The statistical uncertainty of the OEM retrieval (red curve) is plotted against the statistical uncertainty of the traditional retrievals. The uncertainty of the retrieval for the stratospheric and tropospheric lidar systems respectively are shown in black and blue. Right panel: The vertical resolution of the OEM retrieval is shown in red. The vertical resolution of the traditional calculation from the tropospheric lidar system is shown in blue, while the vertical resolution of the retrieved profile produced from the stratospheric lidar system is shown in black.
Fig. 3. The OEM retrieval (red curve) compared to the traditional calculation of ozone using the OHP lidar systems. The tropospheric lidar starts at 2.5 km and extends upward to 14.5 km (blue curve). The ozone profile measured by the stratospheric lidar system (black curve) overlaps with the profile retrieved from the tropospheric lidar system in the UTLS. In this region, the OEM retrievals smoothly transition from relying primarily on the tropospheric lidar measurements to the stratospheric measurements.
Fig. 10. Both the OEM retrieval (red curve) and the traditional retrieval (blue curve) extend from 2.5 km to 14.2 km. The ozonesonde profile is plotted in green. The black dashed line defines the cut-off altitude of the retrieval.
Fig. 9. Averaging kernels for the ozone density for the measurements on 12 July 2017. The horizontal dashed line is the height cut-off above which the sensitivity of the retrieval to measurements is less than 90%. The averaging kernels are only shown every 450 m in altitude. The summation of rows in the averaging kernel matrix, for each specific height, is shown by the red curve.
Fig. 8. OEM ozone-profile retrieval on 14 July 2017 (red curve). The tropospheric traditional retrieval (blue curve) extends from 2.5 km to 14 km, while the stratospheric traditional retrieval (black curve) extends from 12.5 km to 43 km. At the region where the tropospheric and stratospheric lidar measurements overlap, the OEM can smoothly makes a transition from one lidar system’s measurements to the other system’s measurements.
Fig. 1. Averaging kernels for tropospheric-stratospheric ozone measurements. The averaging kernels are only shown every 450 m for lower altitude (from 2.5 km to 11 km height), and every 1500 m in higher altitudes for clarity. As is shown in the red curve, the area of the averaging kernel matrix has a small spike at 11 km, when the stratospheric ozone measurements are included.
Table 2. Measurements periods for the tropospheric and stratospheric lidars systems and launch times for the ozonesondes.
Fig. 7. OEM ozone-profile retrieval on 14 July 2017 (red curve). The tropospheric traditional retrieval (blue curve) extends from 2.5 km to 15 km, while the stratospheric traditional retrieval (black curve) extends from 10 km to 43 km. At the region where the tropospheric and stratospheric lidar measurements overlap, the OEM can smoothly makes a transition from one lidar system’s measurements to the other system’s measurements.
Fig. 2. The percentage difference between the forward model and the actual measurements are shown in blue. The statistical uncertainty is plotted in red. The four plots on top are the stratospheric forward model residuals, and the four plots at the bottom are the tropospheric forward model residuals. For digital counting systems, the Poisson distribution is appropriate and the variance of the measurements at each altitude is the number of photons at that altitude. However, the output signals of the analog channels do not follow a Poisson distribution and to find the variance a 3-point running filter is used. As a result the red line (which indicates the noise of measurements) for the analog channels is more structured then for the digital channels.
Journal Article
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DOI
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Improved ozone DIAL retrievals in the upper troposphere and lower stratosphere using an optimal estimation method
[...]
Ghazal Farhani
,
Robert J. Sica
,
Sophie Godin-Beekmann
,
Gérard Ancellet
,
Alexander Haefele
1
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+1 more
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Institutions (1)
MeteoSwiss
1
20 Feb 2019
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Applied Optics