gesamp working group 38

GESAMP Working Group 38

The Atmospheric Input of Chemicals to the Ocean

GESAMP 39New York, 2012

Recall the IssueRecognition continues to grow concerning the impact of the atmospheric input of both natural and anthropogenic substances on ocean chemistry, biology, and biogeochemistry as well as climate. In the 1980s, GESAMP formed a working group sponsored by WMO, UNESCO/IOC, and UNEP that developed a comprehensive review of the input of atmospheric trace species to the global ocean (GESAMP, 1989). That benchmark effort led to a scientific publication in Global Biogeochemical Cycles that for ~15 years was the state-of-the-art reference in this area, leading to over 700 citations in the literature. That paper is now more than 20 years old, and a new overall look at this issue was needed.


For this reason Working Group 38 was formed during 2008 and it held its first meeting at the University of Arizona, Tucson, AZ, in 2008. Subsequent meetings were held at

IMO in London in 2010 and Malta in 2011.


Sponsors of previous WG 38 efforts have included WMO, IMO, SCOR, SIDA, the European Commission Joint Research Centre, the University of Arizona, and the International Environment Institute at the University of Malta. The new work that will be described later is supported by WMO, IMO, the US National Science Foundation, and SCOR.

The membership of WG 38 has been as follows

Co-Chairs: Robert Duce, USA and Peter Liss, United Kingdom

Members of the Working Group: Alex Baker - United Kingdom Frank Dentener - Italy Keith Hunter - New Zealand Maria Kanakidou - Greece Nilgun Kubilay - Turkey Natalie Mahowald - United States Greg Okin - United States Joseph Prospero - United States Manmohan Sarin - India Vanisa Surapipith - Thailand Ina Tegen - Germany Mitsuo Uematsu - Japan Tong Zhu - China


I. Assess the need for the development of new model and measurement products for improving our understanding of the impacts of the atmospheric deposition of nitrogen species and dust (iron) to the ocean.


II. Review the present information on the atmospheric deposition of phosphorus species to both the marine and terrestrial environments, considering both natural and anthropogenic sources, and evaluate the impact of atmospheric phosphorus deposition on marine and terrestrial ecosystems. Consider whether such a review of any other substances would be useful.

III. Work with the WMO Sand and Dust Storm Warning and Assessment System and with the WMO Precipitation Chemistry Data Synthesis and Community Project to evaluate the needs of the marine community and assist in clearly articulating them in the development of these WMO efforts.

The initial charge for WG 38 was as follows:

Charges I and II have been partially satis-fied by 2 papers that have been published in the peer-reviewed literature:

Okin, G., A. R. Baker, I. Tegen, N. M. Mahowald, F. J. Dentener, R A. Duce, J. N. Galloway, K. Hunter, M. Kanakidou, N. Kubilay, J. M. Prospero, M. Sarin, V. Surapipith, M. Uematsu, T. Zhu, “Impacts of atmospheric nutrient deposition on marine productivity: roles of nitrogen, phosphorus, and iron, Global Biogeochem. Cycles, 25, GB2022, doi:10.1029/2010GB003858, (2011).

Hunter, K.A., P. S. Liss, V. Surapipith, F. Dentener, R. A. Duce, M. Kanakidou, N. Kubilay,, N. Mahowald,, G. Okin,, M. Sarin,, I. Tegen, M. Uematsu, and T. Zhu, “Impacts of anthropogenic SOx, NOx and NH3 on acidification of coastal waters and shipping lanes”, Geophysical Research Letters, 38, L13602, doi:10.1029/2011GL047720 (2011).

The results of these papers were discussed at last year’s GESAMP meeting.


In response to Charge III, you will recall that at the first meeting of WG 38 two reports were developed, and after review by GESAMP they were submitted to WMO:

Report of GESAMP Working Group 38 to the

WMO Precipitation Chemistry Data Synthesis and Community Project

and

Report of GESAMP Working Group 38 to the

WMO Sand and Dust Storm Warning Advisory and Assessment System

These reports satisfied the initial considerations of Charge III of the Terms of Reference. GESAMP 39

New York, 2012

“Atmospheric organic material and the nutrients nitrogen and phosphorus it carries to the ocean” by M. Kanakidou, R. Duce, J. Prospero, A. Baker, F. Dentener, K. Hunter, N. Mahowald, M. Sarin, P. Liss, M. Uematsu, et al.


The third paper developed under Charges I and II was being prepared when the last meetingof GESAMP took place, and many of the results were presented last year. That paper was submitted to Global Biogeochemical Cycles late last fall and we have just received the reviews, which were quite good. We expect the paper to be sent back to the journal before the end of May.

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Organic Carbon Deposition to the Ocean




Nitrogen Deposition to the OceanGESAMP 39New York, 2012



Organic Phosphorus Deposition to the Ocean


At GESAMP 37, WMO proposed that GESAMP WG 38 hold a third meeting in the spring of 2011. At this meeting the WG would look in more detail at some aspects of the third

term of reference, specifically related to dust. GESAMP WG38 was to establish a close cooperation with the WMO Sand and Dust Storm Warning and Assessment System (SDS-WAS) in order to exploit the already existing modelling and observational capabilities of the SDS-WAS project. Thus the meeting in the spring of 2011 was joint between WG 38 and SDS-WAS. This meeting had the title “Expert Workshop on Modelling and Observing the Impacts of Dust Transport/Deposition on Marine Productivity”.



As described last year, the joint workshop meeting of GESAMP WG 39and SDS-WAS was held in Malta from 7-9 March 2011. The meeting was organized around three separate topics, and both plenary discussions and individual group/topic discussions were held. The three topics were:

Topic 1: Improving the quantitative estimates of the geographical distribution of the transport and deposition of mineral matter and its content to the ocean.

Topic 2: Long-term assessment of mineral dust/Fe/P input to the ocean: In-situ observations and marine response utilizing coupled atmospheric transport and ocean biogeochemical modeling and remote-sensing.

Topic 3: Specifying test-bed regions for joint studies of the transport and deposition to the ocean of mineral matter.

The results of the Malta meeting were decribed to GESAMP lastYear. During the past year it was decided to submit these results To the journal Environmental Science and Technology, which was planning a special issue on the marine boundary layer. That paper was submitted in early January, 2012.

The reviews of that paper were received only late last week and I had a chance to look at them only this Sunday. Some work willbe necessary for this paper to be published. The paper is:

Schulz, M., J. Prospero, F. Dentener, I. Tegen, M. Sarin, S. Nickovic, N. Mahowald, L. Ickes, A. Baker, C. Perez Garcia-Pando, S. Rodriguez, P. Liss, and R. Duce, “The atmospheric transport and deposition of mineral dust to the ocean - implications for research needs”, Submitted to Environmental Science and Technology, (2012).


Brief Conclusions

A new research strategy is needed that emphasizes long-term, internationally coordinated network of surface and column atmospheric measurements carried out on selected islands and exposed coastal sites.

In addition, dedicated intensive campaigns and an advancelent in measurement and modeling technologies must be developed to attain a consistent process understanding iof the impact of dust on maribe biogeochemistry.


Future research should focus on the following scientific problems:




Suggested future atmospheric measurement stations




Continued activities of WG 38

GESAMP 38 approved additional work of GESAMP WG 38 to address issues related to the impact of the atmospheric deposition of

anthropogenic nitrogen to the ocean as follows:

1) Update the geographical estimates of anthropogenic nitrogen deposition to

the global ocean made in the Duce et al. (2008) paper in Science, which were based on data from 2005 or earlier. This would utilize newer and more geographically distributed data on anthropogenic nitrogen concentrations over the global ocean and its deposition to the global ocean surface as well as improved models of atmospheric deposition and its impacts.

2) On the basis of 1), re-estimate the amount of additional CO2 that could be drawn down from the atmosphere to the ocean as a result of the increased productivity in the ocean resulting from the additional anthropogenic nutrient nitrogen deposited. This would allow an update on the impact of the atmospheric nitrogen deposition atmospheric radiative properties, relative to the (2008) paper in Science.


New Charge

Continued activities of WG 38

4) Evaluate the extent to which anthropogenic nitrogen delivered to the coastal zone via rivers, atmospheric deposition, etc. is transported to the open ocean, in which regions may this happen, and what its impact is there. (In the 2008 Science paper we assumed that all nitrogen delivered to the coastal zone was sequestered there and did not reach the open ocean, but this may well not be true, and this is something that should be looked at more carefully.)

5) Do a much more detailed estimate of the impact of anthropogenic nitrogen in the area of the Northern Indian Ocean (Arabian Sea, Bay of Bengal) and the South China Sea - the areas that are expected to show the greatest increase of anthropogenic nitrogen deposition over the next decade or so (according to the 2008 Science paper). These very important regions are also areas for which extensive new atmospheric data are now available compared with 5 years ago, and this should enable much more accurate estimates to be made.

3) Provide a much more accurate estimate of the impact of atmospheric anthropogenic nitrogen deposition on the production of additional nitrous oxide in the ocean and its subsequent emission to the atmosphere. This was certainly one of the greatest uncertainties in the 2008 Science paper. This is very important to evaluate accurately, since N2O is such a powerful greenhouse gas, and the emission of additional N2O from the ocean will cancel to some extent the effects of the additional drawdown of CO2 on the radiative properties of the atmosphere.


To undertake this new activity we retained the old WG 38 members who had expertise in nitrogen and added a number of additional experts to participate in the workshop that would address these 5 issues.

The workshop participants are as follows:

Katye Altieri (US), Kevin Arrigo (US),Alex Baker (UK), Doug Capone (US),Frank Dentener (Italy), Robert Duce (US),Katja Fennel (Canada), Jim Galloway (US),Nicolas Gruber (Switzerland, Tim Jickells (UK),Maria Kanakidou (Greece), Julie LaRoche (Canada/Germany),Kitack Lee (Korea), Peter Liss (UK), Jack Middelburg (Netherlands), Keith Moore (US),Slobodan Nickovic (Switzerland), Greg Okin (US),Andreas Oschlies (Germany), Joseph Prospero (US),Manmohan Sarin (India), Sybil Seitzinger (Sweden),Jonathan Sharples (UK), Parv Suntharalingam (UK),Mitsuo Uematsu (Japan), Charlie Zender (US)


The workshop will take place at the University of East Anglia in Norwich, United Kingdom, from 11-14 February 2013.

Our tentative plans for the organization of the workshop is to base it on the 5 new charges outlined above, designating at least 2 individuals to prepare background material before the workshop oneach charge and lead the discussion and subsequent modelingor other effort related to it. We expect that likely several papers will result from this effort.


Thank you


gesamp working group 38

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