1. Inter-comparison of retrieved CO 2 from TCCON, combining TCCON and TES to the overpass flight data Le Kuai 1, John Worden 1, Susan Kulawik 1, Edward Olsen 1, Debra Wunch 3, Run-Lie Shia 3, Brian Connor 2, Charles Miller 1, and Yuk Yung 3 1.Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Mail stop: 233-200, Pasadena, CA 91109 2.BC Consulting Ltd., 6 Fairway Dr, Alexandra 9320, New Zealand 3.California Institute of Technology, 1200 E. California Blvd., Pasadena, CA, 91125 The comparison of CO 2 from TCCON profile retrievals and aircraft overpass data Comparison of dry mole fraction (DMF) profile: f CO2 (z) Comparison of total column-averaged DMF: X CO2 Comparison of partial column-averaged DMF in boundary layer: pX CO2 BLD (combining TCCON and TES) Coincidence criteria Time window selection : Short enough to measure a same air parcel by flight and TCCON. Long enough for sufficient number of profiles from TCCON for a good statistical treatment. Overpass time window Lamont: Lat=36°, Lon=-97° Parkfalls: Lat=46°, Lon=-90° TCCON site DateFlight time window (UTC) Retrieval time window (UTC) Number of retrievals Parkfalls2004/07/1416:18:17 – 16:48:1915:00 – 17:3036 Parkfalls2004/07/1513:11:09 – 15:49:0013:00 – 16:0081 Parkfalls2004/08/1419:46:37 – 22:24:2919:00 – 23:0044 Parkfalls2008/05/1217:1918 – 17:55:2916:00 – 20:0036 Lamont2009/01/3019:43:18 – 20:46:3019:00 – 21:0042 Lamont2009/07/3114:37:00 – 17:31:0014:00 – 18:00111 Lamont2009/08/0215:05:00 – 17:57:0015:00 – 18:0085 Lamont2009/08/0315:14:00 – 18:00:0015:00 – 19:0090 Lamont2010/07/1816:15:39 – 20:27:5416:00 – 20:3079 Aircraft measured dry profile TCCON retrieved wet profile Sa for temperature Sa for CO 2 Convert to dry profile A priori: Retrieved: Parkfalls: Apply averaging kernel FLT_AK: 2004/07/12 2004/07/15 2004/08/02 2008/05/12 2009/01/30 2009/07/31 2009/08/02 2009/08/03 2010/07/18 Lamont: Abstract: The Total Carbon Column Observing Network (TCCON) provides measurements of column abundances of CO2, CO, CH4 and other molecules that absorb in the near infrared with high accuracy and high precision (e.g.< 0.25% for CO2). Therefore, this dataset serves as a link between satellite measurements and ground- based in situ network. In this study, a retrieval algorithm is developed to retrieve the CO2 profiles in addition to the column-averaged dry-air mole fractions (DMF) (X CO2 ). The inter-comparison between the TCCON retrieved CO2 products and flight measurements are performed mainly at Parkfalls and Lamont for now. The retrieved profiles agree well with the overpass flight profile at both sites. TCCON X CO2 have about 1% negative bias to the integrated aircraft data with TCCON operator applied. The root-mean-square of the current available data is about 0.12%. The boundary layer partial column-averaged CO2 fraction can be determined by subtract the column amount within and above free troposphere by TES data from the total column amount by TCCON data. This boundary layer partial column-averaged fraction data also shows a good agreement with the integration of flight profile within the boundary layer. This study demonstrates a method to derive the boundary layer CO2 by combine total column amount measurement (e.g TCCON or GOSAT)and free tropospheric CO2 data (e.g. TES or AIRS). The boundary layer CO2 by combining TCCON and TES allow us to study the temporal and latitudinal variability of CO2 near surface. Without O 2 Correction: With O 2 Correction Total column-averaged DMF comparison Determine boundary layer partial column by combining TCCON and TES data P cuf-off RMS P cut-off 800 hPa600 hPa Total column- averaged DMF TCCON0.42 ppm Partial column- averaged DMF in boundary layer TCCON – TES1.78 ppm0.70 ppm TCCON – A priori7.49 ppm2.61 ppm 800 hPa 600 hPa P cut-off = 600 hPaRMS TCCON0.46 ppm TCCON & TES1.46 ppm TCCON a priori3.2 ppm To determine dry X CO2, the normal way is to remove amount of water from the total amount of air. Our retrieval simultaneously retrieves H 2 O by shift its a priori profile. The derived dry X CO2 using retrieved H 2 O profile has small bias but low precision. Since O 2 can also be retrieved, the method by normalizing the retrieved O 2 not only provides dry X CO2 but also improves the precision. It is noticed that about 1% negative bias is induced because the limited knowledge of the spectroscopy in O 2 band. Profile comparison: Applying the averaging kernel and a priori constraint vector to the aircraft data (Flt) ( which is on TCCON grid) yields Flt_AK, a profile which accounts for the TCCON sensitivity and vertical resolution. Flt_AK also represents the profile that would be retrieved from TCCON measurements in the absence of other errors. The comparison should performed between the TCCON profile (Ret) and aircraft data have had the TCCON operator applied (Flt_AK). These profile comparisons give a good overview of the variability and bias in TCCON profile. Combining TCCON and TES assimilated data, the boundary layer partial column CO 2 is determined by subtract the partial column amount within and above free tropospherefrom the total column amount by TCCON. The remained partial column amount in boundary layer is weighted by the partial column amount of dry air in the boundary layer for. The comparison of to those by integral the flight profile within boundary layer shows small bias and high precision. The knowledge of boundary layer CO 2 was greatly improved by combining TCCON and TES assimilated CO 2 data compared to the climatology a priori. Inter-comparison of TCCON combining TES to SGP flight measurements TES SGP FLT There are more flight measurements at Lamont in 2009 but these CO 2 profiles only go up to 5 to 6 Km. However, it still allow us to compare the boundary layer CO 2 from combining TCCON and TES to the flight data. For the comparison of total column, a priori CO 2 is replace above the ceiling of the flight measurements. Here are sixteen days’ comparison in 2009 from January to December when flight measurements are available. The bias and precision of X CO2 are both consist with previous results. The bias in boundary layer CO 2 stay small but root mean square is increased due to two outliers. These two outliers are because flight boundary layer CO 2 are outside the a priori constrain region.