Abstract
Abstract. The Limb Profiler (LP) is a part of the Ozone Mapping and Profiler Suite launched on board of the Suomi NPP satellite in October 2011. The LP measures solar radiation scattered from the atmospheric limb in ultraviolet and visible spectral ranges between the surface and 80 km. These measurements of scattered solar radiances allow for the retrieval of ozone profiles from cloud tops up to 55 km. The LP started operational observations in April 2012. In this study we evaluate more than 5.5 years of ozone profile measurements from the OMPS LP processed with the new NASA GSFC version 2.5 retrieval algorithm. We provide a brief description of the key changes that had been implemented in this new algorithm, including a pointing correction, new cloud height detection, explicit aerosol correction and a reduction of the number of wavelengths used in the retrievals. The OMPS LP ozone retrievals have been compared with independent satellite profile measurements obtained from the Aura Microwave Limb Sounder (MLS), Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) and Odin Optical Spectrograph and InfraRed Imaging System (OSIRIS). We document observed biases and seasonal differences and evaluate the stability of the version 2.5 ozone record over 5.5 years. Our analysis indicates that the mean differences between LP and correlative measurements are well within required ±10 % between 18 and 42 km. In the upper stratosphere and lower mesosphere (> 43 km) LP tends to have a negative bias. We find larger biases in the lower stratosphere and upper troposphere, but LP ozone retrievals have significantly improved in version 2.5 compared to version 2 due to the implemented aerosol correction. In the northern high latitudes we observe larger biases between 20 and 32 km due to the remaining thermal sensitivity issue. Our analysis shows that LP ozone retrievals agree well with the correlative satellite observations in characterizing vertical, spatial and temporal ozone distribution associated with natural processes, like the seasonal cycle and quasi-biennial oscillations. We found a small positive drift ∼ 0.5 % yr−1 in the LP ozone record against MLS and OSIRIS that is more pronounced at altitudes above 35 km. This pattern in the relative drift is consistent with a possible 100 m drift in the LP sensor pointing detected by one of our altitude-resolving methods.
Highlights
Since late 1980s the production of the human-made halogen compounds that destroy the stratospheric ozone layer has been strictly regulated
In summer 2017 all Ozone Mapping and Profiler Suite (OMPS) Limb Profiler (LP) measurements starting from April 2012 have been processed with the new version 2.5 algorithm
Our analysis shows that OMPS LP retrievals accurately characterize the vertical ozone distribution in different atmospheric regions which are most sensitive to changes in the stratospheric composition and dynamics
Summary
Since late 1980s the production of the human-made halogen compounds that destroy the stratospheric ozone layer has been strictly regulated. Observations show that the concentration of ozone-destroying gases in the atmosphere is declining (WMO, 2014), and stratospheric ozone is expected to recover to the 1980 level over the several decades. Kramarova et al.: Validation of OMPS LP version 2.5 ozone retrievals complicated by a competing effect from increasing concentration of greenhouse gases (that lead to rises in stratospheric ozone due to stratospheric cooling) and large uncertainties in the measurements (e.g., Harris et al, 2015). Unexpected variations in the atmospheric circulation, not captured by models, such as the recent disruption of the quasibiennial oscillation (QBO) (Newman et al, 2016; Tweedy et al, 2017), contribute to additional noise in the trend estimates and emphasize the continued importance of highquality ozone measurements
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