Working Group 2: How and why are the North Pacific distribution patterns of carbon, nutrients and oxygen in the water column changing with time?

The primary goal of Working Group 2 is to synthesize individual data sets into a basin-scale picture of changes in the North Pacific carbon-cycle, with particular emphasis on identifying and explaining decadal time-scale changes in the water-column distribution of carbon, nutrients and oxygen.

To this end, we would like to begin to collect and synthesize existing North Pacific data sets, as well put together results from hindcast simulations with a range of ocean biogeochemistry models. Once we have identified the available data sets and model results, we would like to form a number of smaller teams with specific charges.

At this time, we would like to identify the available data sets. Attached is a pdf file which tabulates those cruises which were included in the initial GLODAP compilation (http://cdiac.esd.ornl.gov/oceans/glodap/Glodap_home.htm). Those cruises that were occupied during the WOCE era (1990s) have been subjected to detailed quality control procedures (significantly beyond just assigning quality control flags) following the procedures described in Lamb et al. 2002 (DSR II, 49, 21-58) in the case of the inorganic carbon properties. Most of the WOCE nutrient and oxygen data were compared using similar, but less extensive procedures. All of these "calibration" procedures were based on the steady state assumption for deep water only. All of the GLODAP North Pacific data can be compiled (either with or without adjustments) and distributed to the entire group as a single file. The older cruises in the GLODAP compilation have generally not be subjected to the same degree of quality control as the more recent cruises.

The immediate question is: "What other data sets exist?" From the literature we are aware of numerous additional cruises in the North Pacific, with high quality data, which are not in GLODAP. Also presumed to be of value are the many repeat cruises to Ocean Station Papa. We therefore would like to ask each of you to provide an inventory of those cruises that you have access to and can provide to this effort, but are not in the GLODAP listing. Most valuable are cruises which contain measurements for all the parameters of interest, but this is certainly not a requirement. Here "all" includes: pressure, temperature, salinity, oxygen, nitrate, nitrite, silicate, phosphate, total inorganic carbon and one other carbon system parameter (alkalinity, pH and/or pCO2). In addition to these, tracer data is of value (CFC, C-14, C-13, H-3, He-3, He-4). Commonly calculated parameters (AOU, theta, potential density, etc.) are not required and will be recalculated to ensure that no differences arise due to different calculation algorithms. Naturally, for this study we must know the units (oxygen and nutrient values in milliliter/liter or micromole/liter will be converted to micromole/kilogram using an assumed measurement temperature of 22C unless the actual measurement temperature is known). Comma separated text files are requested for cruise data.

In order to ensure sufficient time to integrate these new data into GLODAP (which Bob kindly agreed to do for us), we need a response from you with regard to which cruises you can provide by April 14. We then would like to ask for the actual data submission by April 21, i.e. two weeks from now). Please let us know ahead of time if you have difficulties to meet these deadlines, We will try to accommodate your needs as much as possible, but there will be a cut-off time for inclusion.

We would like to make a similar request to the modelers. Please provide us with a short table that lists which parameters you can provide to this effort, and a summary of the model simulation characteristics. Deadline for this inventory list is also April 14. We unfortunately don't have the resources to do a lot of file conversions, etc. We therefore would like to ask you to submit your model data using netcdf format following the GDT conventions (as adopted by OCMIP and the Ocean Inversion Project).

Many thanks for your help and contributions in advance!