Working Group 1: How are air-sea CO₂ fluxes in the North Pacific affected by different modes of variability?

The primary goal of Working Group 1 is to synthesize individual data sets and model results into a basin-scale picture of the North Pacific carbon-cycle, with particular emphasis on answering the question: How are air-sea CO₂ fluxes in the North Pacific affected by different modes of variability?

We intend to evaluate several of the North Pacific data sets and model products in a common framework that allows for a direct comparison of results for the identification of coherent patterns of variability as well as the underlying mechanisms responsible for these patterns. A simultaneous analysis of North Pacific variability with both models and data will be performed. The model runs will be used to predict where variability signals should be most prominent and to evaluate whether the modeled variability is consistent with the data based signals that develop from the synthesis.

In order to get an initial start on our goal prior to the workshop we propose the following strategy:

Split up the work into three regions: tropical Pacific; subtropical North Pacific; and sub-arctic North Pacific. Then for each region determine the following:

(1) Are there enough combined data to provide an estimate of the time series of pCO₂ distributions and CO₂ fluxes using the Takahashi et al. (2002) grid spacing (4°x5°) for at least winter and summer seasons? If so, can we produce some crude first maps with data gaps identified? Can we produce inter-annual maps?

(2) Are there some locations in each region where specific time series data can be used to estimate inter-annual and inter-decadal changes in the CO₂ fluxes? If so, can this be done in the eastern and western parts of each the regions (i.e., eastern equatorial Pacific vs, western equatorial Pacific; HOT vs. 137°E; Ocean Station P vs. KNOT)?

(3) Can we develop empirical equations to estimate pCO₂ variability from SST, Chl. SSS on a regional and/or basin-wide basis?

(4) Can we provide modeled outputs of pCO₂ and CO₂ fluxes for each of these regions (both seasonal maps and detailed fluxes at each of the time series sites) to compare directly with the data?

(5) Can we identify some of the underlying physical and biogeochemical mechanisms controlling variability from the data and model results?

We are suggesting that all data holders contribute their appropriate data sets to the synthesis effort. Alex Kozyr has agreed to collate all of the data at CDIAC and place it on a private www site for only the Working Group I members to access. We would like to receive all of the data by April 15. The regional subgroups (listed below) will then use the combined data to examine the pCO₂ distributions and CO₂ fluxes for each of the three regions before the workshop. All members of working group 1 will be kept apprised of the subgroup progress and asked to contribute ideas of how best to proceed. At the workshop, the entire working group will study the results and determine if there is any continuity for the three regions and decide how to proceed from there.

The aim is to have both the data and model outputs of pCO₂ distributions and fluxes with approximately the same temporal and spatial resolutions for direct comparisons. The time-scales for theses syntheses are regionally dependent, but we should strive to include at least the 1990-2003 timeframe.

For this effort we suggest the following breakdown of responsibilities:

1. Tropical Pacific:

Feely - to contribute eastern Pacific data and a time-series analysis at 110°W

Ishii - to contribute western Pacific data and a time-series analysis at 160°E

Inoue - to contribute western Pacific s data and a time-series analysis at 137°E

Feely (lead with contributions from other members) - provide summer and winter maps of pCO₂ and CO₂ fluxes across the entire equatorial Pacific from 1992-2003.

Chai (lead with contributions from other modelers) - to produce model based time-series analyses and entire equatorial pCO₂ and CO₂ flux maps for equatorial Pacific from at least 1992-2003, or longer if possible.

2. Subtropical Pacific:

Inoue - to contribute western Pacific data and a time-series analysis at about 137°E Takahashi, Nojiri - to contribute subtropical Pacific data

Gruber - to contribute HOT time series data and a time-series analysis at HOT Takahashi (lead with contributions from other members) - to produce summer and winter maps of pCO₂ and CO₂ fluxes in subtropical Pacific from ~1995 to 2003 LeQuere (lead with contributions from other modelers) - to produce model based time-series analyses and pCO₂ and CO₂ flux maps for subtropical Pacific from at least 1995-2003, or longer if possible.

3. Subarctic Pacific:

Nojiri - to contribute subarctic Pacific data and time series analysis at KNOT.

Wong - subarctic Pacific data and time series analysis at Papa.

Takahashi - (lead with contributions from other members) - to produce summer and winter maps of pCO₂ and CO₂ fluxes in subarctic Pacific from ~1995 to 2003.

Christian (lead with contributions from other modelers) - to produce model based time-series analyses and pCO₂ and CO₂ flux maps for subarctic Pacific from at least 1995-2003, or longer if possible.

In addition, we are asking that Kitack Lee work with Taro Takahashi and each of the regional groups to develop empirical equations for pCO₂ in each sub region as a function of SST, SSS, and Chl that is appropriate for extrapolating pCO₂ data both temporally and spatially for the North Pacific. He should use the Takahashi et al (2002) grid spacing to obtain a first look at what we can achieve using extrapolated data.

We ask you to please provide your data to Alex Kozyr by April 15 and model results into the leads of each subregion by May 15 so we can stay within the stated timeline.

We hope that you are as excited about this project as we are. If you have any questions about the organization of this effort, our expectations for your participation, or would like more information about the plan, please feel free to contact Scott Doney or Dick Feely.