Advanced Ultraviolet Radiation and Ozone Retrieval for Applications (AURORA): A Project Overview

Abstract

With the launch of the Sentinel-5 Precursor (S-5P, lifted-off on 13 October 2017), Sentinel-4 (S-4) and Sentinel-5 (S-5)(from 2021 and 2023 onwards, respectively) operational missions of the ESA/EU Copernicus program, a massive amount of atmospheric composition data with unprecedented quality will become available from geostationary (GEO) and low Earth orbit (LEO) observations. Enhanced observational capabilities are expected to foster deeper insight than ever before on key issues relevant for air quality, stratospheric ozone, solar radiation, and climate. A major potential strength of the Sentinel observations lies in the exploitation of complementary information that originates from simultaneous and independent satellite measurements of the same air mass. The core purpose of the AURORA (Advanced Ultraviolet Radiation and Ozone Retrieval for Applications) project is to investigate this exploitation from a novel approach for merging data acquired in different spectral regions from on board the GEO and LEO platforms. A data processing chain is implemented and tested on synthetic observations. A new data algorithm combines the ultraviolet, visible and thermal infrared ozone products into S-4 and S-5(P) fused profiles. These fused products are then ingested into state-of-the-art data assimilation systems to obtain a unique ozone profile in analyses and forecasts mode. A comparative evaluation and validation of fused products assimilation versus the assimilation of the operational products will seek to demonstrate the improvements achieved by the proposed approach. This contribution provides a first general overview of the project, and discusses both the challenges of developing a technological infrastructure for implementing the AURORA concept, and the potential for applications of AURORA derived products, such as tropospheric ozone and UV surface radiation, in sectors such as air quality monitoring and health.

Application of the Complete Data Fusion algorithm to the ozone profiles measured by geostationary and low-Earth-orbit satellites: a feasibility study

“…In the framework of the AURORA project, we simulated ozone products from the instruments mentioned above by using the information available at the beginning of 2016 (ESA, 2011(ESA, , 2012EUMETSAT, 2010;Crevoisier et al, 2014). We applied some simplifications to these specifications: for example, we considered only the UV1 band (neglecting UV2, 300-320 nm), simplified spatial sampling (spacing between pixels and shape) and in some cases a different signal-tonoise ratio (GEO-TIR L2 type, see Table 1).…”

Data Fusion Analysis of Sentinel-4 and Sentinel-5 Simulated Ozone Data

“…The TIR simulator is based on the line-by-line radiative transfer model (RTM) Kyoto Protocol Informed Management of the Adaptation (KLIMA) (Cortesi et al 2014) and uses an optimal estimation retrieval approach (Rodgers 2000) to simulate the ozone profiles, covariance matrices (CMs) and averaging kernel matrices (AKMs) required for the assimilation. The simulation in the VIS wavelength range is performed through a spectral fit using a differential optical absorption spectroscopy (DOAS) approach (Platt 1994).…”

“…In this technique the observations of the different instruments are used to retrieve from each one an independent vertical profile and, a posteriori, an algorithm is implemented to combine into a single estimate the profiles retrieved from the observations acquired by the different instruments. Advanced Ultraviolet Radiation and Ozone Retrieval for Applications (AURORA) is a 3-yr project supported by the European Union in the frame of its Horizon 2020 Call (EO-2-2015) for ''Stimulating wider research use of Copernicus Sentinel Data'' (Cortesi et al 2018). The primary goal of the project is to exploit the complementary measurement capabilities of the instruments on board the S4 and S5 missions, operating on sun-synchronous polar low Earth orbit (LEO) and on geostationary orbit (GEO), respectively, for near-real-time monitoring of the ozone vertical profile with unprecedented accuracy.…”

Harmonization and comparison of vertically resolved atmospheric state observations: methods, effects, and uncertainty budget

“…Despite these attempts to optimize the co-location criteria, some irreducible co-location mismatch usually still affects the comparisons, adding non-negligible random and systematic errors to the difference statistics, and thereby hampering the interpretation of the differences in terms of the quality of the measurements and their reported uncertainties. Several approaches to quantify these co-location difference errors exist; see and Fassó et al (2017) for an overview and some case studies. Particularly appealing is the option to estimate the individual errors from modelbased simulations.…”