Tropospheric column ozone variability from space: results from the first multi-instrument intercomparison

Abstract : Tropospheric ozone is a pollutant detrimental to human health and crop and ecosystem productivity. Tropospheric ozone is also the third most important greenhouse gas (after carbon dioxide and methane). The most recent IPCC estimate of ozone’s radiative forcing has large error bars of ± 50% due to model uncertainties (0.40 ± 0.20 W m-2). Improvements to this estimate require an accurate observation-based quantification of the present-day tropospheric ozone burden (TOB), and greater confidence in chemistry-climate model estimates of TOB in pre-industrial times. Previously, there was only one published observation-based estimate of TOB, derived from the OMI/MLS instruments on NASA’s Aura satellite. Recently, four new satellite products have been developed for measuring TCO and TOB, with two based on the OMI satellite instrument and two based on the IASI satellite instrument. The first intercomparison of these products was published as a component of the Tropospheric Ozone Assessment Report (TOAR). While all five products show the same general tropospheric ozone features across the globe, they differ in absolute TCO quantities and they also differ in terms of decadal trends. The next step is to evaluate all products against the exact same set of in situ ozone observations to gauge the performance of each product in different regions of the world. We will present results from this evaluation which relies on IAGOS commercial aircraft profiles above three regions with high ozone precursor emissions. Western Europe (Frankfurt, Paris, Amsterdam, Düsseldorf, Munich) has the highest frequency of ozone profiling of any location in the world due to daily IAGOS profiles. The monthly mean of TCO above Western Europe shows a significant positive trend of 0.12 ± 0.10 DU yr-1 between 1994 and 2016. The two other regions of interest are the Northeastern US (Philadelphia, Washington, New York, Boston, Montreal) and the Middle East (Tehran, Tel Aviv, Beirut, Riyadh, Abu Dhabi, Dubai). The evaluation will be of greatest interest above the Middle East where the satellites indicate a hot spot of ozone pollution, but they differ widely in terms of ozone trends. In the past, in situ observations have been extremely limited above the Middle East but our evaluation will merge all available IAGOS profiles to establish the long-term trend.
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Submitted on : Tuesday, January 1, 2019 - 4:50:53 PM
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  • HAL Id : insu-01967827, version 1

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Audrey Gaudel, Owen R. Cooper, Valérie Thouret, Brice Barret, Anne Boynard, et al.. Tropospheric column ozone variability from space: results from the first multi-instrument intercomparison. AGU Fall Meeting 2018, Dec 2018, Washington, United States. ⟨insu-01967827⟩

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