Preface

The W-PASS (Western Pacific Air-Sea interaction Study)Project 2006–2010 in Japan—Linkages in Biogeochemical Cycles between the SurfaceOcean and the Lower Atmosphere—

tribute to primary production in the mar-ginal and remote oceanic regions, from theAsian continent to the western Pacific.

(2) Determine the responses of marineecological systems to changes in atmos-pheric composition over the western Pa-cific.

(3) Investigate the production andemission of marine biogenic gases thatmight lead to changes in atmospheric com-position, especially in subtropical andsubarctic regions of the western Pacific.

(4) Evaluate the contribution of marinebiogenic gases to global climate change.

The W-PASS project consisted of 11main, and 12 supportive, research groupsunder four primary research programs (seeFig. 1) with 29 research institutional or-ganizations and 89 scientists from Japan.

A01. Dynamics of AtmosphericComposition

Long-term continuous monitoring ofnitrogen species, both in gaseous andparticulate phases, was carried out withother air pollutants at the National Insti-tute for Environmental Studies (NIES)Atmospheric and Aerosol Monitoring Sta-tion of Cape Hedo, at the north end of theOkinawa main Island facing the East ChinaSea. Simultaneous, comprehensive andhigh time-resolution continuous monitor-ing was conducted for the total NOy andnitrogenous deposition species, particulateNO3

– and NH4+, as well as gaseous HNO3

and NH3. Quantifying the annual trend and

Global Climate change has a significantimpact on biogeochemical cycling in theocean, on atmospheric chemistry, and onthe chemical exchanges between the oceanand the atmosphere. These exchanges in-clude the atmospheric deposition of nutri-ents and metals that control marine bio-logical activity and, hence, the ocean car-bon uptake, and the emission of trace gasesand particles from the ocean because oftheir importance in atmospheric chemis-try and climate processes.

To clarify the interaction processes ofthe boundary between the atmosphere andthe ocean, the Surface Ocean-Lower At-mosphere Study (SOLAS) was establishedas one of the core projects by the Interna-tional Geosphere-Biosphere Programme(IGBP) under the International Council forScience (ICSU) in 2004. Subsequently, theW-PASS (Western Pacific Air-Sea interac-tion Study) was funded in the summer of2006, for 5 years as a part of SOLAS-Ja-pan activity.

The goal of the W-PASS project was toachieve a quantitative understanding of thekey biogeochemical key interactions andfeedbacks between the ocean and the at-mosphere. We aimed to resolve this linkthrough field observation studies over thewestern Pacific, mainly using researchvessels and island observatories. Numeri-cal modeling studies were required for sys-tematic evaluation and quantitative assess-ment. Our objectives were:

(1) Quantify the transport of naturaland anthropogenic materials which con-

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Fig. 1. Overview image of the W-PASS activities. A01: Behavior of atmospheric compositionsfor air-sea interaction (PI: Y. Yokouchi). A02: Gas exchange between air and sea (PI: Y. W.Watanabe). A03: Behavior of biota in sea after air-sea interaction (PI: S. Takeda). A04: Inte-grated modeling for air-sea interaction (PI: Y. Yamanaka). See the detail of each activity in thetext.

the seasonal variability of atmospheric ni-trogen input to the western Pacific enabledus to evaluate the potential impact of theeconomic growth in East Asia on the ma-rine ecosystem in the marginal seas.

Field measurements of marine VOCsin the air and surface seawater took placewith cooperative research on the mecha-nism and controlling factors of marineVOC production based on the cultivation

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of microalgae and molecular biologicaltechniques.

The transport and deposition ofparticulate major ions, trace metals andorganic compounds were measured on-board ship, and at island stations, over themarginal seas of the Asian continent to thewestern North Pacific. The production andemission of biogenic trace gases and thegas-to-particle processes were determinedover the high primary productive regions,especially in the tropical and subarctic re-gions of the western Pacific. Chemical andphysical properties of newly-formednanoparticles were determined by an Aero-sol Time-of-Flight Mass Spectrometer(ATOFMS) on-board ship during theSOLAS research cruises.

A02. Variability of Gas Exchangesat the Air-Sea Interface

Trace organic compounds in seawaterwere determined by a new technique us-ing PTR-MS. Production of methane inoxic seawater using dual (carbon and hy-drogen) isotope tracers was determined, aswell as stable carbon isotopecompositionsof trace non-methane hydrocarbons(NMHCs). The geochemistry of nitrate andnitrous oxide using the triple oxygen iso-tope composition was elucidated for thequantitative estimation of atmosphericdeposition of nitrogen to the ocean.

For a precise evaluation of air-seafluxes of trace gases, an eddy-covariancemethod has been considered to be the di-rect and most reliable technique. In theproject, CO2 and DMS were possible can-didates for the application of the eddy-covariance method. A measurement systemof these trace gas density fluctuations, andship motion correction for the wind veloci-ties, were implemented in this project.

We investigated oceanic parameters forthe prediction of greenhouse gas behaviorwith physical-biogeochemical observa-tions during this project. We also focused

on decadal changes in the subarctic/sub-tropical regions of the North Pacific in or-der to get a quantification of feedback pa-rameters.

A03. Dynamics of the MarineEcosystem

To investigate the speciation andbioavailability of trace metals suppliedfrom the atmosphere to the ocean surface,we studied the dissolution rates of tracemetals from atmospheric mineral dust andtheir speciation in seawater.

The detailed distributions of differentforms of biophilic elements (C, N, P, Si),and their interactions with microbial proc-esses in the surface water column, havebeen elucidated in terms of thebiogeochemical flux between the atmos-phere and the surface ocean.

We examined the ecosystem responsesto the dust (iron) input in the subarctic andsubtropical Pacific with bottle incubation.We also investigated the effects of a ty-phoon as a mechanism to enhance the pri-mary production in the subtropical Pacific.

To examine an abrupt change of pri-mary productivity, we generated satellitedata set on ocean color and sea surfacetemperature before, and after, a typhoonpassing around Japan. We developed anumerical model of a typhoon to simulatethe magnitude of mixing and upwelling inthe sub-surface layer and examined the re-lationship between the moving speed of atyphoon and the magnitude of mixing andupwelling.

A04. Modeling of the Interactionbetween the Oceanand the Atmosphere

In this project, we attempted to bringtogether the outputs from the atmosphericchemical transport model and the marineecosystem model. Results obtained fromthe field observation projects in the

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SOLAS-Japan activities were also com-bined. In particular, we focused on the re-sponses of the marine ecosystem to spo-radic weather disturbances such as a ty-phoon and a strong extra-tropical cyclone,which deepen the mixed layer and shutdown solar radiation over a period of a fewdays to a week. We also investigated theresponses of the marine ecosystem toaeolian dust input using ecosystem mod-els representing iron cycle processes.

Field Observations

High-frequency measurements of me-thyl halides and DMS were carried out inthe marine atmosphere at Hateruma Islandin Okinawa, and Cape Ochiishi inHokkaido, over a period of a year.

We conducted several W-PASS cruisesusing Japanese research vessels and inten-sive atmospheric observations on the is-land station.

SNIFFS (Subtropical Nitrogen FixationFlux Study) I (2–23 June, 2006) andSNIFFS II (18 May–4 June, 2010) cruiseswere carried out in the subtropical regionof the western North Pacific by R/VHakuho Maru.

BLOCKS (Bloom Caused by KosaStudy) cruise (16–29 April, 2007) was car-ried out in the off-Sanriku region of thewestern North Pacific by R/V Tansei Maru.We investigated various patches of phyto-plankton bloom and experienced an inten-sive dust event on-board ship. A newly-developed surface-water clean samplingsystem, ‘Fish’ was used during the R/VHakuho Maru cruise, 24–29, July 2007,and trace metal sampling was carried outin the surface layer around the KuroshioCurrent by R/V Tansei Maru, 21–25 Octo-ber, 2007.

On the R/V Mirai, eddy-covarianceflux measurements were carried out dur-ing a longitudinal transect cruise from Ja-pan to North America along 47∞N and thesubarctic regions during the summer and

the fall of 2007, and during cruises fromJapan to the equatorial and subarctic re-gions during the summer and fall of 2008.

In the spring of 2008, intensive marineatmospheric observations, including directatmospheric deposition measurements,were carried out at the NIES Atmosphericand Aerosol Monitoring Station of CapeHedo at the north end of Okinawa MainIsland facing the East China Sea from 17March to 13 April, 2008.

In summer 2008, in collaboration withthe Japan-IMBER, the SPEEDS (SubarcticPacific Experiment for Ecosystem Dynam-ics Study)/SOLAS cruise was carried outin the subarctic to the subtropical regionin the western North Pacific by R/VHakuho-maru from 29 July to 16 Septem-ber, 2008.

During the R/V Hakuho Maru (KH-09-05) cruise, the W-PASS members collabo-rated with the GEOTRACES group for aninvestigation of trace metals and VOCs inthe Indian Ocean.

Accomplishments of the W-PASSProject

The accomplishments of the 5-year W-PASS project have been published in the500 international peer-reviewed academicpapers listed in this book. The highlightedexciting research topics will be found inthe following chapters.

After the 5-year project, we traced thedevelopment of the young scientists in-volved in the project. Seven students con-tinued with a PhD study from the 37 stu-dents who were awarded a master’s degree.Eleven scientists who earned a PhD havebeen working as a post doc or assistantprofessor. A new PhD got a job in privateindustry. Among 34 post docs working forthe W-PASS project, 7 obtained facultypositions and 22 are keeping their post docpositions. Substantial numbers of youngscientist are working in the SOLAS fieldin Japan.

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We wish to express our appreciation toour colleagues in close collaboration withthe W-PASS scientists, students and stafffor supporting our research activities. Wealso thank Drs Atsushi Tsuda and YasushiNarita for operating the secretariat.

We would like to sincerely thank theadvisory committee members, Drs HajimeAkimoto, Shiro Imawaki, Isao Koike,Akira Taniguchi and Shizuo Tsunogai fortheir thoughtful and constructive opinionsthroughout the period, of this study.

We hope that more new science projectsinvolving collaboration between interna-tional communities will be established in

this new field after the completion of theW-PASS project for further contributionsto global environmental research.“Science is facts. Just as houses are madeof stones, so is science made of facts. Buta pile of stones is not a house and a col-lection of facts is not necessarily science.”Henri Poincaré

March 2014Mitsuo UematsuYoko Yokouchi

Yutaka W. WatanabeShigenobu Takeda

Yasuhiro Yamanaka