M. Reuter, EMS, Berlin, September 2011 Retrieval of atmospheric CO 2 from satellite near-infrared nadir spectra in the frame of ESA’s climate change initiative Retrieval of atmospheric CO 2 from satellite near-infrared nadir spectra in the frame of ESA’s climate change initiative M.Reuter, O.Schneising, M.Buchwitz, J.Heymann, H.Bovensmann, J.P.Burrows Institute of Environmental Physics, University of Bremen, Germany EMS, Berlin, September 2011

M. Reuter, EMS, Berlin, September 2011 Retrieval of atmospheric CO 2 from satellite near-infrared nadir spectra in the frame of ESA’s climate change initiative ESA’s GHG-CCI: Aims and Motivation

M. Reuter, EMS, Berlin, September 2011 Retrieval of atmospheric CO 2 from satellite near-infrared nadir spectra in the frame of ESA’s climate change initiative ESA’s GHG-CCI: Road Map

M. Reuter, EMS, Berlin, September 2011 Retrieval of atmospheric CO 2 from satellite near-infrared nadir spectra in the frame of ESA’s climate change initiative Two in-house algorithms BESD (XCO 2 )WFMD (XCO 2, XCH 4 ) Inversion Algorithm: Optimal Estimation; Full Physics Least-squares; Light path Proxy A-priori constraints: Yes Constant: CO2(p), aerosol, cirrus,... Per pixel: P, T, H2O,... No (constant atmosphere as linearization point for RT) Atmosphere: ECMWFUS Standard (sev. H2O) Aerosols: State vector (APS)Constant; AAI filter (CO2 only) Clouds: State vector (CWP, CTH); Filtering: MERIS 1x1 km 2 RT cloud free; Filtering: O2 & PMD (CO2 only) Fit windows: Merged fit windowsIndependent fit windows Radiative Transfer: SCIATRAN on-lineSCIATRAN LUT Speed: Slow (~15 min./pixel)Fast (~2 min./orbit) Optimized for: AccuracyCompromise accuracy/speed

M. Reuter, EMS, Berlin, September 2011 Retrieval of atmospheric CO 2 from satellite near-infrared nadir spectra in the frame of ESA’s climate change initiative BESD XCO 2

M. Reuter, EMS, Berlin, September 2011 Retrieval of atmospheric CO 2 from satellite near-infrared nadir spectra in the frame of ESA’s climate change initiative Validation with TCCON FTS measurements 350km Park Falls, USA 350km Bremen, Germany 350km Darwin, Australia 350km Lauder, New Zealand Restriction to a limited validation data set due to computational costs Only 4 TCCON sites measured in the full period

M. Reuter, EMS, Berlin, September 2011 Retrieval of atmospheric CO 2 from satellite near-infrared nadir spectra in the frame of ESA’s climate change initiative Comparison with FTS, CarbonTracker, GOSAT Overall good agreement between SCIAMACHY, GOSAT, FTS and CarbonTracker No statistical significant regional biases Single measurement precision ~2.5ppm

M. Reuter, EMS, Berlin, September 2011 Retrieval of atmospheric CO 2 from satellite near-infrared nadir spectra in the frame of ESA’s climate change initiative Comparison with FTS, CarbonTracker, GOSAT Smoothed Results show: Good agreement of year-to-year increase and seasonal amplitude. (Data density allows smoothing only at Park Falls and Darwin)

M. Reuter, EMS, Berlin, September 2011 Retrieval of atmospheric CO 2 from satellite near-infrared nadir spectra in the frame of ESA’s climate change initiative WFMD XCO 2

M. Reuter, EMS, Berlin, September 2011 Retrieval of atmospheric CO 2 from satellite near-infrared nadir spectra in the frame of ESA’s climate change initiative Global increase Computational costs are orders of magnitude lower Processing of global data easily possible A global dataset is available Similar annual global patterns Continuous year-to-year increase of global XCO2

M. Reuter, EMS, Berlin, September 2011 Retrieval of atmospheric CO 2 from satellite near-infrared nadir spectra in the frame of ESA’s climate change initiative CO 2 uptake by growing vegetation Mean wind direction Longitude WestEast XCO 2 F net Assumption: XCO 2 gradient in wind direction approximately proportional to net surface flux F net

M. Reuter, EMS, Berlin, September 2011 Retrieval of atmospheric CO 2 from satellite near-infrared nadir spectra in the frame of ESA’s climate change initiative CO 2 uptake by growing vegetation Calculation of gradients above boreal forests (Canada+Russia): Good agreement with CarbonTracker (year-to-year progression and size) Canada: larger neg. gradients suggest stronger CO2 uptake Russia: less strong gradients suggest weaker CO2 uptake

M. Reuter, EMS, Berlin, September 2011 Retrieval of atmospheric CO 2 from satellite near-infrared nadir spectra in the frame of ESA’s climate change initiative Intercomparison with other XCO 2 algorithms Within the GHG CCI several different XCO2 retrieval techniques are involved: BESD, WFMD, and the algorithms of SRON, University of Leicester, ACOS, and NIES First inter-comparisons with FTS measurements show many similarities but also differences which have to be analyzed

M. Reuter, EMS, Berlin, September 2011 Retrieval of atmospheric CO 2 from satellite near-infrared nadir spectra in the frame of ESA’s climate change initiative THANKS!