Debra Wunch, Geoff Toon, Paul Wennberg, TCCON Partners

Transcription

1 TCCON Update: GGG2014 Debra Wunch, Geoff Toon, Paul Wennberg, TCCON Partners 1

2 New and Upcoming TCCON Stations Newly operational: Edwards (aka Dryden or Armstrong) Tsukuba has replaced their FTS, upgraded the old FTS and moved it to Rikubetsu A new station is being set up in Anmyeondo, South Korea The Four Corners FTS is packed up for shipping to Manaus 2

3 GGG2014 Highlights Laser Sampling Error Correction Updated spectroscopy Many changes to the H 2 O spectroscopy in the cm -1 region based on Kitt Peak cell spectra, affecting retrievals in the H 2 O, HDO, CO and N 2 O windows. A 13 CH 4 line list from HITRAN2012 (plus tweaks) was added, which impacts retrievals in the CO and CH 4 windows. The HITRAN2012 line list for CO was adopted, which has narrower widths. Combined with the H 2 O and 13 CH 4 spectroscopic changes, the CO retrievals are much improved for GGG2014. An additional retrieval window was added for N 2 O. Updated airmass dependences Similar values for CO 2, CH 4, smaller for N 2 O, newly derived value for CO, made possible because of the vastly improved spectroscopy Updated a priori profiles (small changes) Updated TCCON calibration curves 3

4 Laser Sampling Errors ( Ghosts ) Periodic sampling errors in an FTS can cause images of the spectrum to be folded (aliased) back into the original spectrum Causes interference with atmospheric absorption lines, and a bias in retrieved Xco 2 (mostly through O 2 ). Affects TCCON data prior to ~2011 After ~2011 (date differs from site to site), new hardware was installed to eliminate this problem We have developed new software to correct for these sampling errors Before Correction After Correction Ghost region 7899 cm -1 folding frequency Parent region Parent Region (reversed wavenumber axis) 4

5 Operational Laser Sampling Error Correction Algorithm New interferogram resampling algorithm has been developed and implemented in GGG2014 Resolves laser sampling errors ( ghosts ) in most (90% of) TCCON data. Sites without a Si detector are not yet correctable with our new method. The method is seamlessly incorporated in our current algorithm. New resampling algorithm will be applied operationally to: Park Falls, Lamont, Darwin, Wollongong, Lauder 125HR, Saga 125HR, Białystok, Orléans, Garmisch, Ascension Island, Réunion Island, Sodankylä, Dryden, Four Corners/Manaus No correction should be necessary for: Eureka, Ny Ålesund 120HR, Tsukuba 120HR, Lauder 120HR Dohe et al. (2013) method will be applied to: Bremen, Izaña, Karlsruhe, Tsukuba 125HR 5

6 Park Falls Results Laser Sampling Error Correction New interferogram processing code Identical GGG version used in both cases Blue vertical line is when the new laser sampling board was installed 6

7 Lamont Results Laser Sampling Error Correction One instrument intervention (mid 2009) before new laser board was installed 7

8 JPL 2007 Results Laser Sampling Error Correction No instrument interventions during the year. Fortuitously small LSE 8

9 Updated a priori profiles A more realistic interhemispheric gradient was developed for CO, based on aircraft, balloon and satellite profiles. A secular decrease of 1% per year was added to the HF growth rate. Previously, there was no secular dependence of the growth rate. The manner in which the specific humidity from NCEP is converted to mixing ratio was changed, causing up to 1% difference in the lowest altitudes in H 2 O and HDO. Lamont GGG2012, GGG2014 and differences plotted below 9

10 Ties to WMO XCO 2 and XCH 4 Updated TCCON calibration curves Required an additional digit to be added to the slopes due to: Adding several new in situ profiles, including 6 AirCore profile over Lamont, which eliminate the need for stratospheric extrapolation Correction of the laser sampling errors New spectroscopy Results in overall differences in XCO 2 between GGG2012 and GGG2014 of ~0.3 ppm 10

11 Ties to WMO XCO, XN 2 O, XH 2 O 11

12 Overall GGG2014-GGG2012 differences in Lamont GGG2014 lower by ~0.3 ppm in XCO 2 GGG2014 lower by ~2 ppb in XCH 4 GGG2014 higher by ~0.7 ppb in XN 2 O GGG2014 lower by ~0.4 ppb in XCO 12

13 GGG2014-GGG2012 in Lamont XH 2 O XHDO XHF 13

14 TCCON Data Availability and More Information GGG2014 released to TCCON partners in April 2014 New data product delivered to CDIAC by Fall 2014 Permanent archiving DOIs assigned to the datasets netcdf format More information about TCCON and the stations is available from: For up-to-date information about the TCCON data, please sign up to the TCCON Users mailing list: 14