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www.atmos-meas-tech-discuss.net/3/3489/2010/
doi:10.5194/amtd-3-3489-2010
© Author(s) 2010. This work is distributed
under the Creative Commons Attribution 3.0 License.
A geostationary thermal infrared sensor to monitor the lowermost troposphere: O3 and CO retrieval studies
1Laboratoire d'Aérologie, Université de Toulouse, CNRS/INSU, Toulouse, France
2CNRM-GAME, Météo-France and CNRS URA 1357, Toulouse, France
3NILU, N-2027 Kjeller, Norway
4Karlsruhe Institute of Technology, IMK, Karlsruhe, Germany
5Laboratoire Interuniversitaire des Systèmes Atmosphériques, CNRS UMR 7583, Université de Paris-Est, Créteil, France
6National Center for Atmospheric Research, Boulder, Colorado, USA
7Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA
8Astrium-EADS, Toulouse, France
Abstract. This paper describes the capabilities of a nadir thermal infrared (TIR) sensor proposed for embarkation onboard a geostationary platform to monitor ozone (O3) and carbon monoxide (CO) for air quality (AQ) purposes. To assess the capabilities of this sensor we perform idealized retrieval studies considering typical atmospheric profiles of O3 and CO over Europe with different instrument configurations (signal to noise ratio and spectral sampling interval) using the KOPRA forward model and the KOPRA-fit retrieval scheme based on the Tikhonov-Phillips regularization. We then select a configuration, referred to as GEO-TIR, optimized for providing information in the lowermost troposphere (LmT; 0–3 km in height). For the GEO-TIR configuration we obtain around 1.5 degrees of freedom for O3 and 2 for CO at altitudes between 0 and 15 km. The error budget of GEO-TIR, calculated taking account of the principal contributions to the error (namely, temperature, measurement error, smoothing error) shows that information in the LmT can be achieved by GEO-TIR. We also retrieve analogous profiles from another geostationary infrared instrument with characteristics similar to the Meteosat Third Generation Infrared Sounder (MTG-IRS) which is dedicated to numerical weather prediction, referred to as GEO-TIR2. Comparison between GEO-TIR and GEO-TIR2 allows us to quantify the added value of GEO-TIR, a mission complementing the AQ observing system. To better characterize the information provided by GEO-TIR and GEO-TIR2 in the LmT, we retrieve two typical profiles of O3 and CO for different thermal contrast ranging from –10 K to 10 K. The shape of the first averaging kernel (corresponding to the surface level) confirms that GEO-TIR has good sensitivity to CO in the LmT and also to O3 for high positive thermal contrast. GEO-TIR2 has very low sensitivity in the LmT to O3 but can have sensitivity to CO with high positive thermal contrast. To quantify these results for a realistic atmosphere, we simulate it using the chemical transport model MOCAGE (MOdèle de Chimie Atmospherique à Grande Echelle) – this is the nature run. We simulate the O3 and CO spatial and temporal distributions from GEO-TIR observations in the LmT in July 2009 over Europe by sampling the nature run. Results show that GEO-TIR is able to capture well the spatial and temporal variability in the LmT for both O3 and CO, particularly during periods with high positive thermal contrast near the ground and high surface temperature, which results in active photochemistry and a raised planetary boundary layer. These results also provide evidence of the significant added value in the LmT of GEO-TIR compared to GEO-TIR2 by showing GEO-TIR is closer to the nature run than GEO-TIR2 for various statistical parameters (correlation, bias, standard deviation).
Discussion Paper (PDF, 24960 KB) Interactive Discussion (Closed, 4 Comments) Final Revised Paper (AMT)
Notice on Discussion StatusCitation: Claeyman, M., Attié, J.-L., Peuch, V.-H., El Amraoui, L., Lahoz, W. A., Josse, B., Ricaud, P., von Clarmann, T., Höpfner, M., Orphal, J., Flaud, J.-M., Edwards, D. P., Chance, K., Liu, X., Pasternak, F., and Cantié, R.: A geostationary thermal infrared sensor to monitor the lowermost troposphere: O3 and CO retrieval studies, Atmos. Meas. Tech. Discuss., 3, 3489-3534, doi:10.5194/amtd-3-3489-2010, 2010. Bibtex EndNote Reference Manager XML
