Present: Ric Williams, Elaine McDonagh, Brian King, Ute Schuster, Paula Mcleod, Tim Lesworth, Marie-Jose Messias, Andy Watson, Tim Jickells, Alex Baker, Pete Brown, Alex Gardiner
Apologies: George Wolff, Harry Bryden, Richard Sanders,
Susan Leadbetter, Rhiannon Mather, Carol Robinson, Eric Achterberg, Clare
Postlethwaite, Sinhue Torres
A series of science updates were provided for the hydrography (Paula/Elaine/Brian), nutrients (Elaine/Ric), CO2/Anthropogenic CO2 (Ute/Andy/Peter), CFCs (Marie-Jo/Andy), atmospheric inputs (Tim L./Tim J.), deep western boundary changes (Elaine), heat content changes (Ric/Susan). Preparation and requirements for the inverse model were discussed and are reported below.
The presentations and any preliminary results will be made available on a password-protected site: http://www.bodc.ac.uk/36n/restricted/. Consequently, only key points will be presented here:
Paula: The hydrography group has calculated the geostrophic velocity field from the geopotential anomaly. They have also calculated cumulative and overturning transport and are using Gulf Stream transport, depth/ size of overturning, heat and fresh water fluxes, water mass transports, nutrient, carbon and transient tracer fluxes as diagnostic tools for the geostrophic velocity field. The group is at present working on the refinement of OI and velocity fields, the calculation of across-section flux estimates and of fluxes in layers/water masses.
Elaine: Dissolved inorganic N and P have been analysed. Still to do organics, but there have been problems with the instruments (which should be fixed by end of March). However, because of these problems they will use a reagents technique instead on the remaining ~1200 DON+P samples.
Pete: They have mainly been working on the analysis of 26N data, but the work has helped solve generic problems which will be relevant to the 36N analysis. They have successfully merged the analyses from two different machines. However they will have to re-calculate total alkalinity, including a correction for salinity and nutrient concentrations. Brian mentioned it may be possible to do the re-calculations for few samples, over a range of salinities, and apply a linear correction to all the samples. Ric recommended completing analyses over a wide station spacing first and then followed by all stations in order to provide preliminary data in May for the inverse calculations.
ACTION: Pete to investigate best way to do corrections.
Marie-Jo: 1386 samples have been analysed from 82 CTD stations. SF6, CFC-11,CFC-12 data have been calibrated and merged with hydrographic data. Preliminary results show the North Atlantic Deep Waters are well ventilated in the Western Basin compared to the Eastern Basin . The group will be working on optimum multiparameter analysis and transit time distributions next.
Tim L.: 36N samples have been extracted and prepared. They have also got the phosphorous data ready and will have soluble ammonium and nitrate data ready in ~6 weeks. In addition, they will do some isotope analyses and will look at DOC atmospheric inputs.
Elaine: Has been looking at bottom velocities and comparing to the 1981 data.
Ric/Susan/Harry: Work on the watermass census of section and section properties
on isopycnals is in progress. They have also been looking at zonally averaged
temperature differences and Ekman volume fluxes. Also looking at volumetric
changes in temperature going back ~50yrs with implications for storage/mixing.
Claire Powell has been doing work on the cruise report. Aiming to have it completed in 3-4 months. Only a few submissions are outstanding.
ACTION: ALL to send outstanding submissions to Elaine for the cruise report
There is a new BODC 36N data management site at http://www.bodc.ac.uk/projects/uk/36n/
The pages will include a data inventory for the project members to track progress of different 36N datasets.
ACTION: Alex to email people to get estimated time of completion for datasets.
Availability of data was discussed. All data needs to be made available by the end of the grant following NERC rules. Prior to then selected data might be made available on a request basis. The data will only be made available if the appropriate investigator provides permission.
ACTION: Alex to provide a statement about data availability and update the
web when agreed.
Ric and Elaine stressed how a priori estimates are needed for the inverse model. The aim is to have the model assembled by early June with all fields and fluxes ready for a first run of the model so that results can be discussed at the meeting on 21 June.
The measured atmospheric fluxes should be ready by June (with uncertainties) and the group will aim to develop a climatology for the region and provide estimates of nitrogen fixation.
Need to consider seasonal effects on parameters and estimate uncertainties. It is also important to assess the impact of river flows (also include Gibraltar Straights) on the inverse model.
The following timetable for the inverse model was proposed:
Develop 1st guess of circulation: Spring 2006
ACTION: ALL to make sure data ready for Elaine to run model.
ACTION: Tim/Alex to develop climatology and provide estimates of flux uncertainties.
ACTION: Elaine to investigate possible impact of river flows on inverse model.
The importance of having 36N contributions to international conferences was underlined by Ric.
Elaine has submitted an abstract to EGU and Marie-Jo for the conference in Hawaii .
The possibility of having a Royal Society discussion meeting was discussed, which might take ~2 years to organize.
ACTION: Andy and/or NOCS people to talk to Harry and start looking into having a Royal Society meeting.
NERC ROD returns will have to be made shortly. Only one submission for the whole 36N consortium, but with contributions from all members will be made.
ACTION: Alex to send email to participants to help complete ROD. Please include talks, discussions with the press and any ways your work has been disseminated to the wider community.
Next meeting is scheduled for 21 and 22 June 2006 at NOCS with the following themes to discuss:
ACTION: All to think about proposed themes for next meeting.
ACTION: ALL to send outstanding submissions to Elaine for the cruise report.
ACTION: Alex to email people to get estimated time of completion for datasets.
ACTION: Alex to provide a statement about data availability and update the web when agreed.
ACTION: Alex to send email to participants to help complete ROD.
ACTION: ALL to make sure data ready for Elaine to run model.
ACTION: Tim/Alex B. to develop climatology and provide estimates of flux uncertainties.
ACTION: Pete to investigate best way to do total alkalinity corrections.
ACTION: Elaine to investigate possible impact of river flows on inverse model.
ACTION: Andy and/or NOCS people to talk to Harry and start looking into having a Royal Society meeting.
ACTION: All to think about proposed themes for next meeting.
© 2015 NERC.
Last updated: June 8, 2015
