Decadal and Longer-term changes of the CO 2 in the ocean

Transcription

1 The 2 nd GEOSS AP Symposium 15 Apr 2008, Tokyo Decadal and Longer-term changes of the CO 2 in the ocean Masao Ishii Meteorological Research Institute, JMA

2 Background Strong air-sea interaction Distribution of bomb-c14 in the ocean Ocean is considered as a major sink for the anthropogenic CO 2. Little is quantitatively known about the variability in the oceanic CO 2 and its controlling processes. Understanding the ocean s role in regulating the atmospheric CO 2 concentration and its long-term changes is one of the key issues in predicting the future atmospheric CO 2 concentration. Ocean has been acidified due to anthropogenic CO 2 (carbonic acid) increase in the ocean Its status and impact (damage) on the marine ecosystem should be urgently investigated.

3 Contents A brief review of international efforts on the observations of 1. Partial pressure of CO 2 in surface seawater (pco 2 sw ) 2. Dissolved inorganic carbon (DIC or TCO 2 ) in the water columns Data synthesis Climatological view Interannual variability Long-term trend On-going repeat observations Data synthesis Anthropogenic CO 2 Decadal trend On-going repeat observations Implementation plan for the PICES CO 2 data synthesis

4 Climatological air-sea CO 2 flux From 3 million pco 2 data from 1970 to 2006 Air-sea CO 2 Flux = k K 0 (pco 2 sw - pco 2 air) K K 0 : CO 2 transfer piston velocity : CO 2 solubility in seawater Mean annual air-sea CO 2 = -1.4±0.7 PgC yr -1 Takahashi et al. submitted Usefulness : Problems : Understanding ocean carbon cycle processes Validating prognostic ocean carbon cycle models Constraining atmospheric CO 2 inversions Uncertainty in the piston velocity Undersampling in space and time

5 An empirical method to estimate the variability in space and time Data of pco 2 sw, DIC Empirical relationships DIC, TA vs SST, SSS Variability of DIC, TA in space and time Data of T, S vertical profiles [WOA01,GTSPP, TAO/TRITON] Data of SSH [TOPEX/Poseidon] Ocean Circulation Model [MRI.com] Ocean data assimilation [MOVE] SST, SSS Assimilated data Data of atmospheric CO 2 [WDCGG] Dissociation CO 2 solubility constants Weiss 1974 Roy et al Variability of pco 2 sw in space and time Variability of pco sw 2 - pco in space and time CO air 2 Wind field [NCEP/NCAR reanalysis] CO 2 piston velocity Wanninkhof 1992 Variability of air-sea CO 2 flux in space and time

6 Time ( ) - longitude (140ºE - 95ºW) distributions in the equatorial Pacific (mean of 5ºN - 5ºS) SST SSS NTCO 2 pco 2 sw PgC / yr

7 Long-term trend of pco 2 sw in the subtropical zone 137 E line ALOHA (near Hawaii) 137E N Air 1.68 ± 0.03 µatm yr Sea 1.6 ± 0.1 µatm yr -1 pco (µatm) N 1.64 ± 0.04 µatm yr ± 0.2 µatm yr -1 5N ± 0.04 µatm yr ± 0.3 µatm yr Year Observation have been made every late January since early 1980s. Inoue et al., Tellus, Midorikawa et al., Geophys. Res. Lett., Dore et al., Nature, Keeling et al., Global Biogeochem. Cycles, 2004.

8 Long-term trend of pco 2 sw in the western equatorial Pacific warm pool Salinity 34.8, SST 29.0 ºC σ t ± ± ±0.9 Increasing rate / µatm yr ± ± ±0.9 pco 2 sw is increasing, but it is likely that the increase rate is changing in decadal time-scale ± ±0.9 Increasing rate / µmol kg -1 yr -1 Ishii et al. submitted

9 Moorings and underway observations for near-surface water CO 2 Continuous Monthly, Bimonthly Seasonal Biannual Annual Xuelong Ocean Researcher I Tamyang JKEO KEO Ryofu Maru Keifu Maru Araon (2010-) MOSEAN Ka imimoana Pyxis Line-P Kaneohe Bay Columbus Waikato Cape Elizabeth NDBC MBARI M1/M2 Santa Monika Bay TAO 170W TAO 155W TAO 140W TAO 125W Xuelong Fujitrans

10 Dissolved Inorganic Carbon (DIC) at depths CO 2 (g) DIC CO 2 (aq)* -H + (aq) -H + (aq) HCO - 3 (aq) CO 3 2- (aq) = pco 2 sw K 0

11 Global CO 2 Survey in the 1990s : a benchmark ~72,000 sample locations collected in the 1990s with precisions of ± 2 µmol kg -1 for DIC (± 2/2000) ± 4 µmol kg -1 for TA (± 4/2200) Emissions from fossil fuel and cement production 244 ± 20 PgC ( ) Storage in the atmosphere 165 ± 4 PgC Uptake and storage in the ocean 118 ± 19 PgC = + Sabine et al Net terrestrial balance -39 ± 28 PgC

12 Trend of DIC on Isopycnal Surfaces 137ºE, 27.5º- 31.5ºN 2400 σθ 27.3 & ºE, 29.5ºN ºE, 28º- 30ºN, σθ C m / μmol kg C m / μmol kg Year Year At both sites, significant increasing trends of DIC have been observed at 24.9 <= σ θ = < 26.8

13 Time-series stations and repeat lines for water column CO 2 Biweekly Monthly Seasonal Biannual Annual Post-WOCE (2001 -) Planned Not funded K2 Line-P A4 A7 JAMSTEC 155E P01 (2007) P02 (2004) P03 (2005) P16N (2006) P17N (2001) Santa Monica Bay SEATS PR20,21 (2004) P10 (2005) JMA JMA 137E P04W 165E (2014) P14 (2007) HOT P18 (2008) JMA-eq P15S (2009)

14 Japan Meteorological Agency s plan after FY2010 (not funded) Parameters Target Once a year 4 times a year 2 times a year Once a year Temp. Salinity Oxygen Nutrients pco 2 DIC TA ph CFCs Chlorophyl Ocean warming Calibration of Argo pco 2 variability CO 2 accumulation Ocean acidification Every time, to the depth of 2000m, 60 mile intervals. But once every 5 years, to the bottom, 30(15) mile intervals.

15 Development of a new high-precision DIC/TA analyzer in seawater M. Ishii, S. Saito, T. Midorikawa Meteorological Research Institute (MRI) A. Murata Japan Agency for Marine-Earth Science and Technology (JAMSTEC) T. Uji Advanced Earth Science & Technology Organization (AESTO) funded by Ministry of Education, Culture, Sports, Science and Technology (FY ) to contribute to a 10-year implementation plan for GEOSS New high-performance coulometer with dual-beam optical fiber connection (repeatability ± 0.03%)

16 Water column CO 2 data synthesis in the Pacific Ocean is now underway Planned as an activity of The North Pacific Marine Science Organization, Carbon and Climate Section (PICES CC-S) Co-chair : T. Saino (JAMSTEC) and J. Christian (Victoria U.) Working group: R. Feely (PMEL), M. Ishii (MRI), A. Kozyr (CDIAC), A. Murata (JAMSTEC), C. Sabine (PMEL), T. Suzuki (MIRC), N. Tsurushima (AIST) Overall goals: Create a quality controlled data base of water column CO 2 related data for the Pacific. Estimate anthropogenic CO 2 and natural variability in the Pacific from regional to basin scales. Data submission deadline : January Implementation plan

17 Thank you