ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-10-9521-2010 Improved agreement of AIRS tropospheric carbon monoxide products with other EOS sensors using optimal estimation retrievals Warner J. X. 1 Wei Z. 1 Strow L. L. 1 Barnet C. D. 2 Sparling L. C. 1 Diskin G. 3 Sachse G. 3 Joint Center for Earth Systems Technology, University of Maryland Baltimore County, 5523 Research Park Dr., Suite 320, Baltimore, MD 21228, USA NOAA NESDIS ORA, 5200 Auth Road, Camp Springs, MD, USA NASA Langley Research Center, Hampton, VA 23693, USA 08 10 2010 10 19 9521 9533 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/10/9521/2010/acp-10-9521-2010.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/10/9521/2010/acp-10-9521-2010.pdf

We present in this paper an alternative retrieval algorithm for the Atmospheric Infrared Sounder (AIRS) tropospheric Carbon Monoxide (CO) products using the Optimal Estimation (OE) technique, which is different from the AIRS operational algorithm. The primary objective for this study was to compare AIRS CO, as well as the other retrieval properties such as the Averaging Kernels (AKs), the Degrees of Freedom for Signal (DOFS), and the error covariance matrix, against the Tropospheric Emission Spectrometer (TES) and the Measurement of Pollution in the Troposphere (MOPITT) CO, which were also derived using the OE technique. We also demonstrate that AIRS OE CO results are much more realistic than AIRS V5 operational CO, especially in the lower troposphere and in the Southern Hemisphere (SH). These products are validated with in situ profiles obtained by the Differential Absorption Carbon Monoxide Measurements (DACOM), which took place as part of NASA's Intercontinental Chemical Transport Experiment (INTEX-B) field mission that was conducted over the northern Pacific in Spring 2006. To demonstrate the differences existing in the current operational products we first show a detailed direct comparison between AIRS V5 and TES operational V3 CO for the global datasets from December 2005 to July 2008. We then present global CO comparisons between AIRS OE, TES V3, and MOPITT V4 at selected pressure levels as well as for the total column amounts. We conclude that the tropospheric CO retrievals from AIRS OE and TES V3 agree to within 5–10 ppbv or 5% on average globally and throughout the free troposphere. The agreements in total column CO amounts between AIRS OE and MOPITT V4 have improved significantly compared to AIRS V5 with global relative RMS differences now being 12.7%.

 References Aumann, H. H., Chahine, M. T., Gautier, C., Goldberg, M., Kalnay, E., McMillin, L., Revercomb, H., Rosenkranz, P. W., Smith, W. L., Staelin, D., Strow, L., and Susskind, J.: AIRS/AMSU/HSB on the Aqua Mission: Design, Science Objectives, Data Products and Processing Systems, IEEE Trans. Geosci. Remote Sens., 41, 253–264, 2003. Beer, R.: TES on the Aura mission: scientific objectives, measurements, and analysis overview, IEEE Trans. Geosci. Remote Sens., 44, 1102–1105, 2006. Brasseur, G. P., Hauglustaine, D. A., Walters, S., Rasch, P. J., Muller, J. F., Granier, C., and Tie, X. X.: MOZART, a global chemical transport model for ozone and related chemical trac- ers 1. Model description, J. Geophys. Res.-Atmos., 103(D21), 28265–28289, 1998. Deeter, M. N., Emmons, L. K., Francis, G. L., Edwards, D. P., Gille, J. C., Warner, J. X., Khattatov, B., Ziskin, D., Lamarque, J.-F., Ho, S.-P., Yudin, V., Attie, J.-L., Packman, D., Chen, J., Mao, D., and Drummond, J. R.: Operational Carbon Monoxide Retrieval Algorithm and Selected Results for the MOPITT Instrument. J. Geophys. Res., 108(D14), 4399, doi:10.1029/2002JD003186, 2003. Deeter, M. N., Edwards, D. P., Gille, J. C., and Drummond, J. R.: Sensitivity of MOPITT observations to carbon monoxide in the lower troposphere, J. Geophys. Res., 112, D24306, doi:10.1029/2007JD008929, 2007. Deeter, M. N., Edwards, D. P., and Gille, J. C.: Retrievals of carbon monoxide profiles from MOPITT observations using lognormal a priori statistics, J. Geophys. Res., 112, D11311, doi:10.1029/2006JD007999, 2009. Deeter, M. N., Edwards, D. P., Gille, J. C., Emmons, L. K., Francis, G., Ho, S.-P., Mao, D., Masters, D., Worden, H., Drummond, J. R., and Novelli, P. C.: The MOPITT Version 4 CO Product: Algorithm Enhancements, Validation, and Long-Term Stability, J. Geophys. Res., doi:10.1029/2009jd013005, 2010. Drummond, J. R.: Novel correlation radiometer: The length modulated radiometer, Appl. Opt., 28, 2451–2452, 1989. Edwards, D. P., Emmons, L. K., Gille, J. C., Chu, A., Attié, J.-L., Giglio, L., Wood, S. W., Haywood, J., Deeter, M. N., Massie, S. T., Ziskin, D. C., and Drummond, J. R.: Satellite-observed pollution from Southern Hemisphere biomass burning, J. Geophys. Res., 111, D14312, doi:10.1029/2005JD006655, 2006. El Amraoui, L., Attié, J.-L., Semane, N., Claeyman, M., Peuch, V.-H., Warner, J., Ricaud, P., Cammas, J.-P., Piacentini, A., Josse, B., Cariolle, D., Massart, S., and Bencherif, H.: Midlatitude stratosphere – troposphere exchange as diagnosed by MLS O3 and MOPITT CO assimilated fields, Atmos. Chem. Phys., 10, 2175–2194, doi:10.5194/acp-10-2175-2010, 2010. Emmons, L. K., Deeter, M. N., Gille, J. C., Edwards, D. P., Attie, J.-L., Warner, J. Ziskin, D., X., Francis, G. L., Khattatov, B., Yudin, V., Lamarque, J.-F., Ho, S.-P., Mao, D., Chen, J., Drummond, J. R., Novelli, P. C., Sachse, G., Coffey, M. T., Hannigan, J. W., Gerbig, C., Kawakami, S., Kondo, Y., Takegawa, N., Schlager, H., Baehr, J., and Ziereis, H.: Validation of Measurements of Pollution in the Troposphere (MOPITT) CO retrievals with aircraft in situ profiles, J. Geophys. Res., 109, D03309, doi:10.1029/2003JD004101, 2004. Emmons, L. K., Pfister, G. G., Edwards, D. P., Gille, J. C., Sachse, G., Blake, D., Wofsy, S., Gerbig, C., Matross, D., and Ne ìde ìlec, P.: Measurements of Pollution in the Troposphere (MOPITT) validation exercises during summer 2004 field campaigns over North America, J. Geophys. Res., 112, D12S02, doi:10.1029/2006JD007833, 2007. Emmons, L. K., Edwards, D. P., Deeter, M. N., Gille, J. C., Campos, T., Nédélec, P., Novelli, P., and Sachse, G.: Measurements of Pollution In The Troposphere (MOPITT) validation through 2006, Atmos. Chem. Phys., 9, 1795–1803, doi:10.5194/acp-9-1795-2009, 2009. Fisher, J. A., Jacob, D. J., Purdy, M. T., Kopacz, M., Le Sager, P., Carouge, C., Holmes, C. D., Yantosca, R. M., Batchelor, R. L., Strong, K., Diskin, G. S., Fuelberg, H. E., Holloway, J. S., Hyer, E. J., McMillan, W. W., Warner, J., Streets, D. G., Zhang, Q., Wang, Y., and Wu, S.: Source attribution and interannual variability of Arctic pollution in spring constrained by aircraft (ARCTAS, ARCPAC) and satellite (AIRS) observations of carbon monoxide, Atmos. Chem. Phys., 10, 977–996, doi:10.5194/acp-10-977-2010, 2010. Ho, S., Edwards, D. P., Gille, J. C., Luo, M., Osterman, G. B., Kulawik, S. S., and Worden, H.: A global comparison of carbon monoxide profiles and column amounts from Tropospheric Emission Spectrometer (TES) and Measurements of Pollution in the Troposphere (MOPITT), J. Geophys. Res., 114, D21307, doi:10.1029/2009JD012242, 2009. Kopacz, M., Jacob, D. J., Fisher, J. A., Logan, J. A., Zhang, L., Megretskaia, I. A., Yantosca, R. M., Singh, K., Henze, D. K., Burrows, J. P., Buchwitz, M., Khlystova, I., McMillan, W. W., Gille, J. C., Edwards, D. P., Eldering, A., Thouret, V., and Nédélec, P.: Global estimates of CO sources with high resolution by adjoint inversion of multiple satellite datasets (MOPITT, AIRS, SCIAMACHY, TES), Atmos. Chem. Phys., 10, 855–876, doi:10.5194/acp-10-855-2010, 2010. Kulawik, S. S., Osterman, G., Jones, D. B. A., and Bowman, K. W.: Calculation of altitude-dependent Tikhonov constraints for TES nadir retrievals, IEEE Trans. Geosci. Remote Sens., 44, 1334–1342, doi:10.1109/TGRS.2006.871206, 2006. Lamarque J.-F., Khattatov, B., Yudin, V., Edwards, D. P., Gille, J. C., Emmons, L. K., Deeter\textbf, M. N., Warner, J., Ziskin, D., Francis, G., Ho, S., Mao, D., and Chen, J.: Application of a bias estimator for the improved assimilation of Measurements of Pollution in the Troposphere (MOPITT) carbon monoxide retrievals, J. Geophys. Res., 109, D16304, doi:10.1029/2003JD004466, 2004. Luo, M., Rinsland, C., Fisher, B., Sachse, G., Diskin, G., Logan, J., Worden, H., Kulawik, S., Osterman, G., Eldering, A., Herman, R., and Shephard, M.: TES carbon monoxide validation with DACOM aircraft measurements during INTEX-B 2006, J. Geophys. Res., 112, D24S48, doi:10.1029/2007JD008803, 2007. Luo, M., Rinsland, C. P., Rodgers, C. D., Logan, J. A., Worden, H., Kulawik, S., Eldering, A., Goldman, A., Shephard, M. W., Gunson, M., and Lampel, M. C.: Comparison of car- bon monoxide measurements by TES and MOPITT: Influence of a priori data and instrument characteristics on nadir atmospheric species retrievals, J. Geophys. Res., 112, D09303, doi:10.1029/2006JD007663, 2007. Maddy, E. S. and Barnet, C. D.: Vertical resolution estimates in Version 5 of AIRS operational retrievals, IEEE Trans. Geosci. Remote Sens., 46(8), 2375–2384, 2008. McMillan, W. W., Barnet, C., Strow, L., M. Chahine, Warner, J., McCourt, M., Novelli, P., Korontzi, S., Maddy, E., and Datta, S.: Daily Global Maps of Carbon Monoxide from NASA's Atmospheric InfraRed Sounder, Geophys. Res. Lett., 32, L11801, doi:10.1029/2004GL021821, 2005. Nam, J., Wang, Y., Luo, C., and Chu, D. A.: Trans-Pacific transport of Asian dust and CO: accumulation of biomass burning CO in the subtropics and dipole structure of transport, Atmos. Chem. Phys., 10, 3297–3308, doi:10.5194/acp-10-3297-2010, 2010. Pan, L., Gille, J. C., Edwards, D. P., Bailey, P. L., and Rodgers, C. D.: Retrieval of tropospheric carbon monoxide for the mopitt experiment, J. Geophys. Res., 103, 32277–32290, 1998. Pfister, G. G., Emmons, L. K., Edwards, D. P., Arellano, A., G Sachse, and Campos, T.: Variability of springtime transpacific pollution transport during 2000–2006: the INTEX-B mission in the context of previous years, Atmos. Chem. Phys., 10, 1345–1359, doi:10.5194/acp-10-1345-2010, 2010. Rodgers, C. D.: Inverse Methods for Atmospheric Sounding, Theory and Practice, Ser. Atmos. Oceanic Planet. Phys., 2, World Sci., Hackensack, NJ, USA, 2000. Rodgers, C. D., and Connor, B. J.: Intercomparison of remote sounding instruments, J. Geophys. Res., 108 4116, doi:10.1029/2002JD002299, 2003. Sachse, G. W., Hill, G. F., Wade, L. O., and Perry, M. G.: Fast-response, high-precision carbon monoxide sensor using a tunable diode laser absorption technique, J. Geophys. Res., 92, 2071–2081, 1987. Singh, H. B., Brune, W. H., Crawford, J. H., Jacob, D. J., and Russell, P. B.: Overview of the summer 2004 Intercontinental Chemical Transport Experiment-North America (INTEX-A), J. Geophys. Res., 111, D24S01, doi:10.1029/2006JD007905, 2006. Singh, H. B., Brune, W. H., Crawford, J. H., Flocke, F., and Jacob, D. J.: Chemistry and transport of pollution over the Gulf of Mexico and the Pacific: spring 2006 INTEX-B campaign overview and first results, Atmos. Chem. Phys., 9, 2301–2318, doi:10.5194/acp-9-2301-2009, 2009. Sparling, L. C.: Statistical Perspectives on Stratospheric Transport, Rev. Geophys., 38(3), 417–436, doi:10.1029/1999RG000070, 2000. Stohl, A., Berg, T., Burkhart, J. F., Fj\'æraa, A. M., Forster, C., Herber, A., Hov, Ø., Lunder, C., McMillan, W. W., Oltmans, S., Shiobara, M., Simpson, D., Solberg, S., Stebel, K., Ström, J., Tørseth, K., Treffeisen, R., Virkkunen, K., and Yttri, K. E.: Arctic smoke – record high air pollution levels in the European Arctic due to agricultural fires in Eastern Europe in spring 2006, Atmos. Chem. Phys., 7, 511–534, doi:10.5194/acp-7-511-2007, 2007. Strow, L., Hannon, S., Machado, S., Motteler, H., and Tobin, D.: An Overview of the AIRS Radiative Transfer Model, IEEE Trans. Geosci. Remote Sens., 41, 303–313, 2003. Susskind, J., Barnet, C. D., and Blaisdell, J. M.: Retrieval of atmospheric and surface parameters from AIRS/AMSU/HSB data in the presence of clouds, IEEE Trans. on Geosci. Remote Sens., 41, 390–409, 2003. Tangborn, A., Stajner, I., Buchwitz, M., Khlystova, I., Pawson, S., Burrows, J., Hudman, R., and Nedelec, P.: Assimilation of SCIAMACHY CO observations: Global and regional analysis of data impact, J. Geophys. Res., 114, D07307, doi:10.1029/2008JD010781, 2009. Turquety, S., Clerbaux, C., Law, K., Coheur, P.-F., Cozic, A., Szopa, S., Hauglustaine, D. A., Hadji-Lazaro, J., Gloudemans, A. M. S., Schrijver, H., Boone, C. D., Bernath, P. F., and Edwards, D. P.: CO emission and export from Asia: an analysis combining complementary satellite measurements (MOPITT, SCIAMACHY and ACE-FTS) with global modeling, Atmos. Chem. Phys., 8, 5187–5204, doi:10.5194/acp-8-5187-2008, 2008. Warner, J. X., Comer, M. M., Barnet, C. D., McMillan, W. W., Wolf, W., Maddy, E., Sachse, G.: A Comparison of Satellite Tropospheric Carbon Monoxide Measurements from AIRS and MOPITT During INTEX-A, J. Geophys. Res., doi:10.1029/2006JD007925, 2007. Worden, J., Sund-Kulawik, S., Shephard, M. W., Clough, S. A., Worden, H., Bowman, K., and Goldman, A.: Predicted errors of tropospheric emission spectrometer nadir retrievals from spectral window selection, J. Geophys. Res., 109(D9), D09308, doi:10.1029/2004JD004522, 2004. Yurganov, L. N., McMillan, W. W., Dzhola, A. V., Grechko, E. I., Jones, N. B., and van der Werf, G. R.: Global AIRS and MOPITT CO measurements: Validation, comparison, and links to biomass burning variations and carbon cycle, J. Geophys. Res., 113(D9), doi:10.1029/2007JD009229, 2008. Zhang, L., Jacob, D. J, Bowman, K. W.: Ozone-CO correlations determined by the TES satellite instrument in continental outflow regions, Geophys. Res. Lett., 33, L18804, doi:10.1029/2006GL026399, 2006.