Proposal for a UK SOLAS Observatory at Cape Verde SOLAS Observatory... · 1 Proposal for a UK SOLAS Observatory at Cape Verde Lucy Carpenter, University of York and Mike Pilling,

1Proposal for a UK SOLAS Observatory at Cape Verde

Lucy Carpenter, University of York and Mike Pilling, University of Leeds,

with advice from the UK SOLAS Monitoring Group (Mike Pilling, Leeds; Lucy Carpenter, York; Jim Gunson, MetO; Gideon Henderson, Oxford; Peter Simmonds, Bristol; Bill Sturges, UEA;

Steve Thorpe, Bangor; and Doug Wallace, Kiel)

Summary

• A long term monitoring site is proposed on the island of Sao Vicente, Cape Verde. The site is close to and downwind of the Mauritanian upwelling, a region of high primary marine productivity, and is in a region that contributes substantially to global chemistry-climate interactions, yet has few long-term measurements.

• The site will be established in collaboration with D-SOLAS and US scientists. • UK SOLAS will be primarily responsible for establishment of a trace gas laboratory at Calhau on

Sao Vicente, measurement of atmospheric trace gases, overhaul of the RV Islandia, a Cape Verdean research vessel, and marine surface measurements en route to and at a representative open ocean site upwind of the trace gas laboratory.

• The project has been divided into two phases. Phase 1 covers the first two years of monitoring and includes the establishment of the site, the installation and operation of the trace gas instruments, overhaul of the RV Islandia and the subsequent measurement of surface marine properties. The costs of this phase are £1.022M. The second phase covers the subsequent two years and consists of staff and running costs for operation of the site, totalling £309k. Continuation to Phase 2 will require a full report and agreement of the UK SOLAS steering committee.

• Subject to funding, German scientists, primarily through D-SOLAS, will establish, equip and run an oceanographic mooring at the pelagic site. They will also provide aerosol, some additional trace gas measurements and full meteorological measurements at Calhau; funding is already in place to support these measurements.

• It is intended that US scientists will measure trace gas profiles above and below the surface at the mooring to provide information on air-sea gas exchange.

• The observatory will be run in collaboration with the Instituto Nacional de Desenvolvimento das Pescas (INDP, fisheries) and Instituto Nacional de Meteorologia e Geofísica (INMG, meteorology and geophysics) on Cape Verde. They are key partners in the successful operation of the observatory, providing facilities and employing the ‘on-the-ground’ managers and technicians.

• The observatory will be established initially to support campaign style field measurements in UK SOLAS, through the provision of a long running dataset to facilitate campaign planning and interpretation. Provided the site meets expectations with regard to data quality and relevance, further funding will be sought to establish it as a continuing long term observatory.

• The project and work at the observatory will be coordinated by a steering group, comprising representatives of the main partners. A data policy will be established permitting use of data across the consortium. BADC/BODC will provide data archiving for the UK SOLAS datasets.

Outline of proposal The proposal is structured in five Sections. Section 1 provides the necessary background to the proposal and outlines the overall rationale for an observatory at Cape Verde, the measurements that are proposed and the links to international activities, including those with consortium members. Section 2 sets the measurements in the overall context of global and regional ocean and atmosphere interactions and also provides more detailed data on the Cape Verde site. Section 3 details the instruments, the installation and the staff required. The instrumentation includes that from UK SOLAS and from consortium partners. Section 4 discusses the observatory requirements of the UK SOLAS community, based on the proposals received in Funding Round 1, and also the potential interactions with the wider community. Section 5 gives a timeline for observatory development and measurements and details costs. Appendix 1 analyses the requirements of the UK SOLAS community in greater detail than Section 4.

1

21. Introduction 1.1 Background The overall aim of the UK SOLAS directed programme is to advance understanding of climatically-significant interactions between the atmosphere and ocean, focusing on material exchanges that involve ocean productivity and atmospheric composition. Whilst much of the programme focuses on short-term field and laboratory measurements, the science plan also recognised that there is a need “To develop time series for marine and atmospheric observations…and, if feasible, establish an atmospheric monitoring station at an open ocean site (with research users)”. In order to further define the scientific rationale and investigate practicalities for the proposed UK SOLAS observatory, UK SOLAS set up a Core Monitoring Group. The group identified two fundamental aims of such an observatory: i) To provide a regional focal point and long-term data context for relatively short-term UK SOLAS

campaigns, experiments and process studies. Since atmosphere-ocean feedbacks are the main topic of interest for the programme, such studies – and the observatory – need to be in an area subject to natural seasonal atmospheric and/or oceanic variability.

ii) To initiate long-term studies of inter-annual variability and trends in marine troposphere composition

and associated meteorological, geophysical and oceanographic factors at an open-ocean site that is representative of a region likely to be sensitive to future climate change, and is minimally influenced by local effects and intermittent continental pollution. The collection of such data (hopefully to be continued beyond the lifetime of the UK SOLAS programme) and their integration with satellite-based work will permit evaluation and improvement of regional and global ocean-atmosphere models.

Cape Verde was selected as the preferred location for the UK SOLAS Observatory by the Monitoring Group and approved by the Steering Committee following assessment of 16 island sites. This decision was based on the scientific rationale and logistic constraints considered by the SC meeting on 23 August 2004 (paper UK SOLAS O4/26i). The SC approved further planning for a marine and atmospheric observatory on Cape Verde, on the basis that costings and collaborations needed more attention before firm funding commitments could be made. 1.2. Outline rationale for a Cape Verde atmospheric and marine observatory Long-term observation is fundamental to the understanding of global changes in air quality, atmospheric oxidation capacity, and climate. Such changes impact marine ecosystems and the atmosphere is, in turn, influenced by ocean physical and biogeochemical processes. Cape Verde (16oN, 24oW) is situated in the tropical Eastern North Atlantic Ocean, a region which is central to the chemistry – climate system:

• The oxidation of methane, a potent greenhouse gas, occurs predominantly within the tropics owing to a combination of high water vapour and radiation which leads to high concentrations of hydroxyl radicals. High temperatures within the tropics enhance the oxidation of methane in this region with the result that ~75% of methane oxidation occurs between 30°S and 30°N [Lawrence et al., 2001].

• The production and loss of tropospheric ozone, again an important climate gas, is dominated by

activity within the tropics, due to the high photochemical activity [Horowitz et al., 2003].

• The injection of species into the stratosphere occurs predominantly within the tropics, so species which are able to perturb the stratospheric ozone chemistry must first be processed through the tropics [Bridgeman et al., 2000].

• Cape Verde is located in an area of massive dust transport from land to the ocean, and is thus

ideal for investigating impacts of dust on the marine ecosystem

• The site is ‘downwind’ of an area of high primary productivity (the Mauritanian upwelling), thus a Cape Verde Observatory would provide unique information on links between upwelling and atmospheric composition changes.

2

3Thus for many aspects of the chemistry-climate system, understanding the processes and feedbacks occurring with the tropical region is of central importance. Despite their crucial role, the tropics are under-populated with long-term observations, as compared to mid-latitudes and high-latitudes, as shown by Figure 1.

Figuhttp: 1.3. The sulphcommea18O/1analphyscontmeaboun UK Srepremeaorgacamenvisserieordinaime 1.4. The with whic

re 1 Locations of atmospheric observing sites. Map obtained from the NSDC website //www.ndsc.ws/.

Summary of proposed measurements

proposed atmospheric measurements to be made by UK SOLAS are O3, CO, NO2, NO2, dimethyl ide (DMS), reactive halocarbons, volatile organic compounds (VOCs), oxygenated volatile organic

pounds (OVOCs) and a meteorological suite. In addition, we will benefit from (i) high-precision surements of CO2, CH4, N2O, CO, SF6, the ratio of O2/N2, and Ar/N2 and the isotope ratios 13C/12C and 6O on CO2 and O2 currently made by regular (weekly or bi-weekly) flask sampling and subsequent ysis of the flasks at the laboratory by MPI-Jena (Prof. Martin Heimann), (ii) aerosol chemical and ical characterization by the University of Leipzig (Dr. Hartmut Hermann), and (iii) potentially, if funded, inuous halogen oxide measurements by the University of Heidelberg (Prof. Ulrich Platt). Radiosonde surements are made on the nearby island of Sal, providing information on the physical structure of the dary layer.

OLAS will establish monthly visits of the Cape Verdean research vessel R.V. Islandia to a pelagic site sentative of open ocean conditions and immediately 'upwind' of the atmospheric monitoring site to

sure biogeochemical parameters (to include nutrients, dissolved oxygen, chlorophyll, particulate nic nitrogen and carbon, carbonate chemistry), and physical parameters. During short term “intensive” paigns, further measurements could be added to this suite including dissolved trace gases. It is aged that the pelagic site will later become the location for a D-SOLAS long term oceanographic time-s station. Subject to UK SOLAS SC approval, the oceanographic measurements will initially be co-ated by a UK SOLAS PDRA based at IFM-GEOMAR, managed by Prof. Doug Wallace. This funding is d at facilitating the establishment of the ocean site and developing links with D-SOLAS.

Links to international activities

combination of atmospheric meteorological and chemical parameters proposed here are compatible the developing IGACO (International Global Atmospheric Chemistry Observations) theme of IGOS-P, h addresses issues such as air-quality, chemistry-climate interactions and ozone. The strong relevance

3

4of the Cape Verde site to a wide variety of IGOS-P themes implies that this site can deliver an efficient use of resources, data of high scientific impact, and that the Observatory can be strongly supportive of the Earth System approach advanced by the GEO. IGACO has strong linkages with the Global Atmospheric Watch (GAW) program of the World Meteorological Program. If long-term funding is available, i.e. if the project is extended beyond Phase 1, we intend to integrate the atmospheric and meteorological measurements of the monitoring site into the Global Atmospheric Watch (GAW) program of the World Meteorological Program and thereby benefit from the calibration and dissemination expertise of this WMO program. The strong links to Germany have been outlined in 1.3. The Cape Verde Instituto Nacional de Desenvolvimento das Pescas (INDP, fisheries) and Instituto Nacional de Meteorologia e Geofísica (INMG, meteorology and geophysics) are key partners in the successful operation of the observatory, providing facilities and employing the ‘on-the-ground’ managers and technicians. Through visits to Cape Verde and the workshop ‘Towards a West African Science Logistics Centre’ (funded by the Volkswagen Foundation, June 2004), Prof Wallace and partners of the EU FP6 bid TENATSO (Tropical Eastern North Atlantic Time-Series Observatory) have developed good relationships with INMG and INDP. In addition, collaborative opportunities are possible with Prof Wade McGillis, who has proposed that his Air-Sea Interaction spar (ASIS) mooring should be deployed as part of the marine observatory. ASIS measures trace gas profiles above and below the ocean surface. 2 Scientific rationale 2.1 General justification for an observatory at Cape Verde 2.1.1 Ocean-atmospheric chemistry-climate interactions: Cape Verde receives North Atlantic marine air along the NNE trade winds, allowing the long-term study of both background Atlantic air, expected to be frequently influenced by the Mauritanian upwelling, and associated oceanic gases, and air heavily impacted by continental inputs under westerly flow. Long term studies of oceanic and other reactive trace gases at this site will allow the study of ocean-atmospheric chemistry-climate interactions at the heart of the UK-SOLAS programme. Two potentially major climate-related feedbacks involving the ocean and the atmosphere, are: (1) climate change alterations of ocean circulation and upwelling and consequent changes in oceanic gas emissions; (2) effects of climate-related changes in deposition of continental dust on marine ecosystems, including biogenic gas production. Both of these feedbacks can be studied very effectively in the vicinity of Cape Verde. Changes in upwelling dynamics off Mauritania will be resolved using the continuous CO2/O2 measurements of MPI-Jena. In the long-term, oceanographic time-series information from immediately “upwind” of the atmospheric monitoring site (made by D-SOLAS) will help resolve the extent to which atmospheric signals of air-sea CO2/O2 exchange are forced locally in the nearby pelagic North Equatorial Countercurrent, or remotely in the Mauritanian upwelling region. The chemical nature of depositing aerosols can affect the biological activities on the surface of the ocean and hence carbon sinks and marine productivity. Mills et al [2004] have shown experimental evidence that community primary productivity in the tropical North Atlantic is nitrogen-limited, and that nitrogen fixation is co-limited by iron and phosphorus. Saharan dust additions were seen to stimulate nitrogen fixation, possibly because dust supplied both iron and phosphorus. Given that iron supplies in this region are at a global maximum, it is perhaps surprising that iron (dust input) can still be limiting there. The results imply that the region’s enormous dust input may fuel a globally significant amount of nitrogen fixation. In turn, the sensitivity of the dust/iron input to conditions in Africa and atmospheric transport patterns means that large future climate-forced changes in oceanic nutrient (fixed-nitrogen) inventories associated with land-use and climate change are possible. The proposed observing site would be a valuable platform from which to assess productivity variations associated with changes in upwelling and dust input. Long term measurements of trace gases and aerosols can be used to address a number of interactions:

• Continuous measurements of ocean source gases including DMS, reactive halocarbons, VOCs and OVOCs by UK SOLAS will provide a link between ocean/atmosphere forcings such as aerosol deposition and changes in upwelling dynamics, to ocean gas emissions and atmospheric chemistry. The hypothesised climate feedback mechanism involving DMS is well known [Charlson et al., 1997] yet there are still many uncertainties. Understanding the budget of DMS in the tropics and its variability will help resolve some of these uncertainties.

• The effects of reactive halogen species (RHS) on DMS oxidation either directly through the

reactions of BrO or IO or indirectly through perturbations to the HOx budget will potentially be

4

5important to climate forcing through the change in the ability to repopulate the aerosol distribution [von Glasow et al., 2002]. There have been no long-term studies of the reactive halogens which contribute to tropospheric halogen oxide concentrations (CHxBry, CHxIy) and the proposed long-term measurements will offer a much needed data set to help constrain global models of halogen chemistry. It has been hypothesised that photooxidation of RHS leads to formation of CCN and hence contributes to regional and possibly global radiative budgets and climate forcing.

• VOCs play significant roles in determining the concentrations of methane, ozone, and organic

aerosols, which, in turn, play important roles in the atmospheric oxidative and climate systems. It is known that there are significant emission and deposition fluxes of organic compounds to the oceans; in the marine environment they will play a significant role in the cycling of oxidants. There is evidence that formaldehyde, ethanal and propanal are produced photochemically in the sea-surface microlayer or photic zone [Zhou & Mopper, 1997], and recent work suggests a net flux of methanol into the North Atlantic ocean [Carpenter et al., 2004]. Recent field campaigns over the Pacific Ocean have found that the concentrations of certain OVOCs (notably aldehydes) to be substantially higher than would be suggested by conventional chemistry [Singh et al., 2003,]. The high concentrations of these species has a substantial impact on the concentrations of HOx and the speciation of NOy found over these remote regions and leads to changes to the balance between ozone production and destruction and to the global oxidizing capacity of the atmosphere. Debate remains as to the source of these oxygenated compounds with missing chemistry, or production on the surfaces of aerosols being suggested as possible explanations. Understanding the budgets of these marine derived trace gases is currently of fundamental importance to understanding the photochemistry of the tropical and extra-tropical marine boundary layer.

2.1.2 Atmospheric pollutants and photooxidants and their regional impacts Because of its huge potential to produce hydroxyl radicals (OH), the tropical troposphere is a major contributor to the global atmosphere’s oxidative capacity. For example, around 40% of the loss of the climatically important gas methane occurs within the tropical boundary layer [Lawrence et al., 2001]; over 80% of this within the tropical MBL. Thus potential perturbations to the OH concentrations or O3 concentration in the tropics through regional or global changes in atmospheric pollutants may present significant climate implications. Time-series measurements of O3, NO, NO2 and CO together with aerosol concentration and composition data (the latter from D-SOLAS), will form the basis to support assessments of the regional impact of pollution transport from Europe and/or North Africa to the tropical troposphere. We expect to observe direct outflow of dust and biomass burning plumes from Africa, allowing quantification of pollution impacts from this region and their atmospheric oxidation pathways. Biomass burning plumes, which result in enhanced photooxidant and aerosol levels, will be characterised by CO/CO2 ratios. Measurements in “background” marine air, i.e. air masses which have been transported over long distances from over the Northwest Atlantic, will contribute to the global database on the changing background atmospheric composition. Specifically, the increase in background tropospheric ozone –current levels are now sufficient to affect plant growth (Barnes et al., 2002) – is attributed to intercontinental transport of pollutants. Continuous measurements of O3 and NO and NO2 will supply a basis for assessment of the influence of long-range transport on photo-oxidant concentrations in the tropical troposphere and permit calculation of the efficiency of ozone production, which is a strong function of NOx levels. 2.1.3 Support for intensive field campaigns in UKSOLAS Although there are significant ‘stand alone’ science benefits to be obtained from an observatory, a strong rationale for the UK SOLAS initiative is that it will complement the programme’s field campaigns, experimental studies and modelling activities. To determine the match to the requirements of the UK SOLAS community, PIs for the 25 Round 1 proposals were asked in early December to complete a questionnaire (on the basis of one response per project). Of the 12 responses received to date, all but 2 indicated some level of interest in the observatory. This aspect is discussed further in section 4. 2.2 Detailed analysis of the suitability of the Cape Verde site 2.2.1 Site location A small or moderate-sized island inevitably provides better sampling of marine air (from a wider range of wind directions) than either a large island or a coastal continental site. The UK SOLAS Core Monitoring group focused its attention on islands in the North and South Atlantic. This was primarily for logistic

5

6reasons - to maximise opportunities for associated ship- and aircraft-based research, and minimise ‘routine’ access costs from the UK. However, several science considerations also applied. Thus the Atlantic provides the full suite of polar to tropical conditions; the mid-Atlantic ridge system offers a range of open-ocean island options; and there are many opportunities for linkages with previous and on-going research effort. Sixteen Atlantic island sites were considered, from Spitzbergen (Svalbard) to South Georgia. Bermuda, the Azores, Cape Verde islands and Ascension Island were short-listed as potential sites offering good opportunities to study current uncertainties relating to continental dust inputs and marine emissions affecting cloud formation in relatively unpolluted oceanic areas, both key science areas in the UK SOLAS Science Plan. On the basis of 5-day back trajectories (using the ECMWF T106/L31 wind field and the John Methven trajectory code) and global chemical transport model predictions (using the Harvard GEOS-CHEM model run at 4x5 degrees by Mat Evans, U. Leeds), and also the potential of co-funding from other sources, the group concluded that the optimum site is Cape Verde. Back trajectories indicated that the islands are subject both to the African dust plume and to clean marine air, including occasional air sources from the southern hemisphere Atlantic (with a 5 day origin in the region of Ascension Island). A suitable site for atmospheric observations on Cape Verde has been identified by partners of (D-SOLAS) and a VW Foundation bid. The site is located on a NW facing sandy beach at Calhau near Mindelo on Sao Vicente, 16.848N, 24.871W, adjacent to the ocean, with the prevailing trade winds blowing directly off the ocean (Fig 2a). There are no obvious major coastal features such as extensive shallows or large seaweed beds. Such a site offers a rare opportunity for ground-based studies of clean marine air, free from local coastal macrophyte interferences (in contrast, Mace Head, Ireland has strong coastal influences particularly on halogenated gases). Two sites have been proposed for the marine station, as marked on Figure 2b along with the proposed position of the atmospheric observatory on Sao Vincente. The nearer site is favoured, being just as representative of the open ocean (depth is 3000m), but much closer to Mindelo, greatly reducing the cost of occupying the station (in time and money). The prevailing wind is from the NE, so either site is up-wind of the proposed atmospheric site.

Figure 2a. Cape Verde and the location of Sao Vicente

6

7

Figure 2b Bathymetric map of the region of the northern islands of the Cape Verde group, with proposed marine and atmospheric observatory sites marked. 2.2.1 Back-trajectory modelling Two air-mass back trajectory analyses have been conducted independently, by D-SOLAS researchers (Fig 3a) and by Mathew Evans (Leeds) for UK SOLAS (Fig 3b). Although there are differences between these analyses – for reasons that have not yet been investigated – both show that Cape Verde receives atmospheric inputs primarily from the north-east, from both marine and continental sectors. As specific UK SOLAS fieldwork campaigns will focus on different aspects of atmospheric chemistry and composition, the timings of dust, pollution and biomass burning events must be considered when planning ship- and aircraft-based studies in this region.

b. a.

2.2 InfoCaseaexp

.2 Seasonality of dust inputs rmation on atmospheric aerosol loading is ava

pe Verde, maintained by the CNRS Laboratoiresonal patterns for aerosol optical thickness (reonent (smaller values indicate larger particles)

Figure 3. Air-mass back trajectory foot-print analyses produced for the Cape Verde region. Scaling and analysis period not known for 1a, hence may not be directly comparable with 1b (5 day back-analysis for 20002000 based on ECMWF analysed winds)

ilable from the AERONET sun photometer on Sal Island, d’Optique Atmosphérique, Lille. Figure 4 shows lated to total dust load) and for the size-related Angstrom [Tanré et al., 2003]. However, most of the atmospheric

7

8loading passes over Cape Verde; deposition to the land surface and nearby ocean is determined by vertical profiles, size distributions and rain wash-out. Most rain in Cape Verde falls during November and December with the rest of the year being almost entirely dry.

Figure 4. Monthly mean data (± SD) for 1994-99 from Sal AERONET station for a) aerosol optical thickness and b) Angstrom exponent (Tanré et al, 2003). 2.2.3 Biomass burning The pattern of biomass burning in Africa follows a well determined seasonal cycle related to the seasonal shift in the Inter-Tropical Convergence Zone (ITCZ). Thus maximum emissions of anthropogenic biomass burning aerosol from the sub-Sahelian regions of northern Africa occur during December to February with very few emissions occurring during August to November. Gas phase tracers (e.g. hydrocarbons and methyl chloride) and aerosol composition (e.g. the ratio of nitrate (NO3

-) to non-sea-salt sulphate, Formenti et al. 2003) can be used to assess whether air-mass composition has been influenced by biomass burning. 2.2.4 Pollution The 5-day footprint for air reaching Cape Verde is mostly oceanic, or covers land that is relatively unpopulated (Fig 3). Nevertheless, the air-mass trajectories indicate that earlier origins of atmospheric inputs may include continental Europe or North America, hence influenced by pollution plumes. Supportive evidence is provided by the Saharan Dust Experiment (SHADE), with evidence of aged fossil fuel plumes, probably from North America, affecting the Cape Verde region [Formenti et al. 2003]. It will therefore be necessary to use tracers of anthropogenic activity such as NOX, CO, hydrocarbons and halocarbons, taking care to use tracers that can distinguish between biomass burning and long range transport of anthropogenic pollution. 2.2.5 Concentration ranges and seasonality of atmospheric trace gases The GEOS-CHEM model has been used to obtain preliminary estimates of likely ranges and seasonal patterns at Cape Verde for atmospheric concentrations of 18 trace gases of interest to UK SOLAS (M Evans et al, Leeds; unpublished). Strong seasonal variability is shown for alkanes, alkenes, isoprene and ammonia (≥10-fold annual ranges), also DMS, NOx, NOy and acetaldehyde (2-5 fold ranges). Concentrations of O3 and CO are predicted to be less variable, spanning approximately 20-40 ppbv and 90-130 ppbv, respectively. These model results were used as the basis for specifying instrument capabilities for UK SOLAS (Section 5; Table 1). However, they have not been verified by field data for the Cape Verde region - and therefore provide a series of hypotheses to be tested by the observatory, with the opportunity to significantly improve the GEOS-CHEM parameterisation and its global applicability. 2.3 Other relevant projects in the Cape Verde region

8

9Several other research projects and programmes relevant to UK SOLAS are currently either underway or planned for the Cape Verde region. Three of particular significance are briefly described below (excluding those with direct interests in the observatory as potential partners, covered in Section 3) . • AMMA (African Monsoon Multidisciplinary Analysis www.ofps.ucar.edu/amma) is a multi-disciplinary

study of the West African monsoon involving field campaigns, observing systems and modelling activities by US and European researchers. As part of the Special Observation Period of AMMA (in 2006/7) a series of aircraft campaigns will be conducted over NW Africa. UK-AMMA is the national contribution, supported by a NERC consortium grant and involving Investigators at CEH, Liverpool, Leeds, York, UEA and Cambridge. Discussions between Professor Joe Prospero and Dr Phil Williamson, science co-ordinator of UK SOLAS, indicate that there is a strong possibility of interaction between UK SOLAS and International AMMA;

• DABEX (Dust And Biomass Experiment) is a study of biomass burning and desert dust aerosol plumes

in the Cape Verde region, led by the UK MetO. It will be based around measurements made during flights (~40 hr) and at surface sites at M’Bour (Senegal), Sal (Cape Verde), Banizoumbou (Nigeria) and Lamto (Ivory Coast) in January 2006. The study will address the hypothesis that mineral dusts ameliorate direct radiative forcing by biomass burning aerosols.

•

•

Figure 5. TACE Observational Strategy. The proposed observing sysextensions along 23 oW and 5-10oE, equatorial subsurface moorings ameteorological and tide gauge stations, enhanced float/drifter coveragatmospheric soundings along 23 oW, ship-of opportunity XBT lines and

3. Instrumentation and staffing The importance of setting up the proposed UK SOLAS observatpartners was highlighted by the Steering Committee because of

• Maintaining activities at the site beyond the lifetime of U • The costs associated with establishing an observatory w

measurements on both sides of the air-sea interface. Potential partnership arrangements for establishing and maintaibeen developed through proposed collaborations with D-SOLASUS scientists (led by Wade McGillis). These links provide opporpotential for substantial added value. 3.1 UK SOLAS installations The instrumentation and costs are detailed in section 5. It is envmeasurements, and the gas phase aerosol measurements will bUK SOLAS provides the main trace gas measurements, togetheIslandia, the Cape Verde research vessel:

TACE (Tropical Atlantic Climate Experiment, part of CLIVAR www.clivar.org/science/TACE_EXEC.pdf;) plans to extend the PIRATA (Pilot Research Moored Array in the Tropical Atlantic) set of moorings to the region around Cape Verde. Figure 5 shows the positions of monitoring buoys proposed by TACE.

The locations at 10o and 20oN would provide a physical oceanographic and atmospheric context for the proposed SOLAS observatory at Cape Verde.

tem includes: PIRATA long 23oE and at 10oW, island e in the eastern TA, repeated selected glider transects.

ory in collaboration with international two areas of concern:

K SOLAS.

ith the capability to make a wide range of

ning an observatory at Cape Verde have and Martin Heimann (MPI-Jena) and with

tunities for possible cost-sharing with

isaged that the bulk of the marine e made by D-SOLAS. It is proposed that r with CTD measurements on the RV

9

10• Gas phase measurements are designed to provide the long term measurements identified in

section 2. : CO, O3, NOx, CH4, non methane hydrocarbons, oxygenated volatile organic compounds, halocarbons, dimethyl sulphide. The instruments will be housed in two purpose built 20’ shipping containers. Funding is also needed for site running costs, construction of a sampling tower, site security and site running costs.

• Marine measurements. Funding is needed for overhaul and maintenance of the RV Islandia, which is central to the CTD measurements of nutrients, dissolved oxygen, chlorophyll, particulate organic nitrogen and carbon and carbonate chemistry that will be made within UK SOLAS

• Proposed staff. Two UK PDRAs are needed each for 24 months, over a 3 year period, to (i) commission and install the instruments and provide training for Cape Verde staff and (ii) to provide additional support for the instruments, especially for calibration methodologies and quality control, and to act as data manager. A third PDRA is requested for one year to coordinate marine measurements from IFM-GEOMAR and to act as a link to D-SOLAS.

• Cape Verde staff, funded through UK SOLAS are (i) a local site manager (ii) two technicians (one marine, one atmospheric and (iii) a night security guard.

• Travel costs are requested for scientific support, training and project management. • It is proposed that the project is conducted in two phases, with separate funding and with a

requirement on approval of the project by the UK SOLAS steering committee before the second phase is funded. The first phase is of 3 years duration (1 year set up and 2 years measurements) and the second phase is of 2 years duration.

3.2 German Installations It is hoped that funding from D-SOLAS will be in place by early 2006. D-SOLAS plans include the following:

• Marine time-series station. Because of concerns regarding biofouling and damage by fishing vessels, the ocean mooring will be sub-surface (measuring physical parameters below 50 m) with upper ocean measurements achieved by regular occupations of the marine station by the RV Islandia, as above, and other research vessels during campaigns.

• Aerosol monitoring: IfT-Leipzig (H. Hermann) will provide aerosol sampling and chemical and data

analysis. The instruments will include cascade impactors, condensation particle counter, differential mobility particle sizer, optical particle counter and equipment for measurement of total aerosol mass loading and for chemical composition (major ions and trace metals). The organic composition of the aerosol will be analysed on a non-routine basis. Funding is being sought through D-SOLAS for this activity, although even if this fails a core contribution will be established with IfT institute funds.

• Heidelberg (U.Platt) will provide a MAX DOAS system for halogen oxide measurements (eg BrO

and IO).

• In addition, MPI-Jena (M. Heimann) will provide a full meteorological suite for the observatory, one container laboratory, and flask sampling and analysis of greenhouse gases. This activity is separate from D SOLAS.

3.3 US Installation The involvement of Wade McGillis will provide the Air-Sea Interaction Spar (ASIS) mooring which would be deployed as part of the marine observatory. ASIS has the capability to measure trace gas profiles above and below the ocean surface using high-tech sensors. Further discussions with Prof McGillis at Halifax NS and UEA have confirmed the viability of this idea. Such a mooring could provide both important information on air-sea gas exchange at the site and a structure on which UK SOLAS could attach additional instrumentation. 3.4 Coordination, data management and exploitation Activities at the observatory (laboratory construction, instrument installation and calibration, measurements) will be coordinated by a steering group consisting of representatives of the main partners. A data policy will be developed at an early stage covering access to datasets by partners. The UK SOLAS data will be archived by BADC/BODC. The trace gas laboratory will be managed, through the PDRAs, by NCAS/DIAC (the Distributed Institute for Atmospheric Composition, one the NERC Centres for Atmospheric Science), DIAC has wide experience of field measurements, the establishment of the observatory will be facilitated by

10

11its experienced scientists. The datasets will be exploited by DIAC, in conjunction with the Atmospheric Chemistry Modelling Support Unit at Cambridge. 4. Survey of UK SOLAS community requirements and of potential user

involvement and co-support 4.1 Requirements of proposals submitted to Round 1 of UK SOLAS 4.1.1 Use of observatory and of monitoring data Based on information given in proposals and survey responses, 11 proposed projects stand to benefit from the UK SOLAS marine and atmospheric observatory, with interest split roughly equally between the marine and atmospheric observations. Two projects have proposed whole 'work plans' around use of observatory facilities to make their own measurements: The RHEMOA proposal (PI McFiggans) wishes to make use of the atmospheric facilities to measure a range of trace gas and aerosol parameters during a 6 week intensive campaign during summer 2007. The proposal submitted by PI Achterberg (The impact of atmospheric dust derived material and nutrient inputs on tropical North Atlantic near-surface plankton microbiota) intends to make regular measurements of a suite of biological and chemical oceanographic parameters over a 2 year period, taking samples from the marine site and making mooring-based continuous measurements; and also wishes to use atmospheric observatory facilities to conduct experiments into the effect of collected dust on microbial communities in microcosms of water sampled from the marine site. Two further proposals have expressed interest in using the observatory facilities for their own measurements – DODO (PI Highwood) wished to deploy an Aerosol Time of Flight Mass Spectrometer (AToFMS) at the atmospheric site for a 6 week period, and PI Schaefer (Enzymes and genes of DMS-production and -oxidation and their role in controlling DMS emissions) expressed an interest in water samples from the marine site in the survey response, although does not specifically mention this requirement in the proposal. Five additional projects expressed interest in observatory data output in survey responses (and in proposals), again with a roughly equal split between the marine and atmospheric sites. These responses have been rated by their interest in data output, on a scale of 1 to 3 (Appendix 1). Two further projects have been listed as having interest in data output, although they do not explicitly express this in survey response / proposal. They have been added because they are likely to be making measurements of observatory-relevant parameters in the Cape Verde region during their fieldwork campaigns. 4.1.2 Links to ship- and aircraft-based campaigns In advance of any funding decisions, a meeting was held in Reading (9-10 Feb, 2005) to discuss the fieldwork requirements of proposals submitted to the first UK SOLAS funding round. This meeting identified potential interest in ship and aircraft campaigns off NW Africa. Hence, time-series data collected at a land-based site on Cape Verde would be of interest to the research projects involved in these campaigns. The proposed field studies that would benefit from background data supplied by a UK SOLAS Observatory include: 1. Ship-based studies in the Mauritanian upwelling (May 2006 or 2007) The objectives of this two-ship exercise are to study trace gas production and emission from the upwelling, and investigate resulting atmospheric influences. The projects involved are RHEMOA (PI McFiggans), Upwelling and Trace Gas Production (PI Robinson) and DMS Photoxidation (Uher) 2. Dust-focused ship and aircraft campaigns off NW Africa (Campaign 1 - January and February 2006;

Campaign 2 - February-March 2007) Campaign 1 would be timed to coincide with the Met Office Dust And Biomass Experiment (DABEX) study incorporating land-based stations and aircraft campaigns over NW Africa. If the relevant proposals (Highwood [DODO] and Achterberg) are successful, UK SOLAS would extend the DABEX aircraft campaigns over the ocean and investigate the influence of dust deposition on marine biogeochemistry from a ship positioned off-shore. Campaign 2 would be a transect study out of Cape Verde investigating how Aeolian dusts are processed during transport in the marine atmosphere (PI Achterberg).

11

124.2 Opportunities for research-user involvement and co-support

All governmental and private sector research-users on the UK SOLAS database (c 25 contacts) have been informed of plans for the Cape Verde observatory, and have been invited to comment on their potential involvement. Whilst the MetO/Hadley Centre has responded very positively, no other direct interest has yet been expressed. Particular effort was made with regard to DfID (who replied that scientific research is outside their remit, other than in the areas of policy/human development) and two oil companies involved in exploratory drilling in the Mauritanian EEZ (Dana Petroleum and Woodbridge– no response to date). 5. Total costs and funding scenarios Two phases of the project have been costed: “Phase 1” is basic infrastructure and instrumentation to allow for set up and 2 years of measurements vital to UK SOLAS research projects, and “Phase 2” is a 2 year extension to the measurements, subject to the successful implementation of Phase 1, the requirements of the UK SOLAS community, and approval by the UK SOLAS committee. Phase 1 includes set up of two atmospheric container laboratories at Sao Vicente with O3, NOx, CO, DMS, OVOCs, VOCs, halocarbons and meteorological measurements plus refurbishment and costs of the RV Islandia for regular ocean surveys, and Phase 2 includes staff time and consumables for a further 2 years of measurements. Some spare container space will be made available for short-term “intensive” measurements in the laboratory containers, although mostly such measurements will be expected to arrive with their own infrastructure (e.g. laboratory container). The first laboratory container, instrumented with a meteorological suite, CO, O3 and GC equipment (DMS, halocarbons, VOCs and OVOCs) could be shipped and installed at Cape Verde 6 months after the start of the project, allowing initial testing of power supplies etc. to the site, with the commercial NOx equipment arriving 4-6 months later (the chosen ANNOx model takes 10-12 months from ordering to delivery). Refurbishment of the Cape Verde research vessel Islandia and installation of a Rosette sampler and other equipment is expected within a 6 month period. Thus, the full suite of atmospheric and marine measurements should be in place ~ 1 year after initialisation. Cape Verde personnel will be trained to run and trouble shoot equipment by UK staff employed on the project. This will allow, after the first 15 months, UK personnel to work half-time on the project whilst it is managed day-to-day by Cape Verde staff. Two UK PDRAs are to be employed to work on atmospheric measurements in Phase 1 (both for 2 years over 3 years). One will commission and install the instruments and provide training to the Cape Verde staff whilst the other will initially provide dual support for instrumentation (e.g. dedicated to calibration standard methodology) and later become the data manager, providing quality control for the data and submitting it in appropriate format in near real time to the data centres. These staff will be employed by NERC DIAC (Distributed Institute for Atmospheric Composition) research institutes. A third 1-year PDRA will be employed to co-ordinate the marine measurements from IFM-GEOMAR, Kiel, which will facilitate the bilateral partnership between UK-SOLAS and D-SOLAS and rapid set-up of the marine measurements by building upon the existing relationship between IFM-GEOMAR and the Cape Verde institutes. It is envisaged that further funds from D-SOLAS will extend this position into 3-4 years. Overall co-ordination of the Observatory should be co-ordinated by a Steering Group made up of UK, German and Cape Verdean partners, with regular (twice yearly) meetings at Cape Verde to review progress, assess data quality, and decide actions. A timeline for the Phase 1 stage of the project is shown below.

12

13Timeline for Cape Verde Observatory Set up and Running Phase 1

UK SOLAS Cape Verde Observatory Year 1 Year 2 Year 31. Equipment commissioning and set up 1.1 Commission NOx instrumentation 1.2 Commission CO, O3, and met. instrumentation

1.3 Commission 2 x custom lab containers

1.4 Commission/build custom GC equipment

1.5 Develop and test calibration system (permeation tubes) for GCs

1.6 Refurbishment of RV Islandia, commissioning of Rosette sampler and marine equipment

2. Equipment population at Cape Verde 2.1 Install and test CO, O3, met. and GC instrumentation at CV in lab container #1

2.2 Install and test NOx instrumentation at CV in lab container #2

2.3 Install marine sampling equipment on RV Islandia

3. Running of Observatory 3.1 Fortnightly CTD sampling using RV Islandia 3.2 Continuous atmospheric measurements

3.3 Intensive training phase of CV by UK personnel

3.4 Quarterly visits of UK personnel to CV

4. Personnel 4.1 UK Atmospheric Instrument PDRA

4.2 UK Data PDRA

4.3 UK/Germany Marine Instrument PDRA

4.4 Cape Verde Atmospheric Instrument Science Manager

4.5 Cape Verde Atmospheric Instrument Technician

4.6 Cape Verde Marine Instrument Technician

4.7 Night security guard

The current status of the costing exercise is given in Tables 1-4, including instrument purchase and maintenance, infrastructure, personnel and travel costs. Proposed instruments and methodologies are based on literature values, modelled concentration ranges (Section 2.1.5), and known analytical detection limits. The survey of PIs’ interests (Section 4) of this report shows that all measurements included in Table 1 are directly relevant to UK SOLAS science. Additional measurements/infrastructure to be funded via D-SOLAS, including aerosol chemical and physical chemical characterisation and an instrumented mooring at the site, clearly bring complementary to the suite of UK-SOLAS measurements. Other potential measurements include the addition of an ASIS mooring by Prof. Wade McGillis’s group, bringing further ‘added value’, and substantially improving capabilities to make seawater measurements. Table 4 (costing summary) shows that the total cost for setting up (1 year) and running for 2 years a UK SOLAS observatory would be around £1 million. Phase 2 is estimated at ~ £300k. References Barnes et al., Plant resistance to ozone: the role of ascorbate In: Air Pollution and Plant Biotechnology (Eds. K. Omasa, H.Saji, S.Yousefian, N. Kondo) 2002 Bridgeman et al., J. Geophys. Res., 105 (D21), 26493, 2000 Carpenter et al, Global Biogeochem. Cycles, 18 (4), doi:10.1029/2004GB002294, 2004 Charlson et al Nature, 326, 655-661, 1987 Formenti et al., J. Geophys. Res., 108 (D18), doi:10.1029/2002JD002648, 2003 Horowitz et al., J. Geophys. Res., 108 (D24): 4784, 2003 Lawrence et al., Atmos. Chem. Phys., 1, 37–49, 2001 Mills et al., Nature, 4297, 292-294, 2004 Singh et al., Geophys. Res. Lett., 30, art. no. 1862, 2003 Tanré et al, J. Geophys. Res., 108 (D18), doi:10.1029/2002JD003273, 2003 von Glasow et al, J. Geophys. Res., 107 (D17): art. No. 4323, 2002 Zhou and Mopper, Mar. Chem., 56, 201-213, 1997.

13

1

Target measurement Methods, capital costs & running costs

Key to funding scenarios x Deployed by UK SOLAS at

cost x

x Deployed with Phase 2 funding at cost x

0 Deployed by D-SOLAS or other funding at no cost to UK SOLAS

0 Deployed by MPI-Jena at no cost to UK SOLAS

Mea

sure

men

t

Low

est l

ikel

y

C conc

entr

atio

n

ape

Verd

e

Met

hod

or

inst

rum

ent

Lim

it of

de

tect

ion

Cap

ital c

ost

(£k)

A

nnua

l ru

nnin

g

(£)

A

oper

ator

pp

xro

time

perw

eek

Exce

pton

al

inf

truc

rer

ira

stu

eq

uire

men

ts

Phas

e 1

Phas

e 2

CO 40 ppb Aerolaser 3001 2 ppb 20 3 1 - 29 6

Greenhouse gases n/a Flask sampling n/a n/a n/a n/a n/a 0 0

O3 + NOX 1 ppt (NO) ANNOXA1 ~2 ppt 140 10 1 Bottled

gases 160 20

Halocarbons <0.02 ppt Automated GCMS 0.02 ppt 80 10 5 Bottled

gases 110 20

NMHCs 2 ppt (propene) CH4 1ppm

OVOC’s 50 ppt (formaldehyde)

DMS

40 ppt

Dual channel automated GC-FID2

60 10 5 Bottled gases 90 20

BrO, IO < 1 ppt MAX-DOAS3 ? 60 (E) 9 - - 0 0

Aerosol size distribution, chemical composition and physical characterisation

n/a Various4 n/a ? ? ? - 0 0

Physical structure of atmosphere n/a Radiosonde

(fortnightly)5 n/a n/a 2.5 1 - 5 5

Atm

osph

ere

Met and physical Meteorological suite

n/a n/a 6 0 0 -

6

0

Physical water column structure n/a Microcat (x6)6 n/a 18 3 2 ASIS

buoy 0 0

Nitrate /nitrite profile 0.2 µM 3x optical nitrate sensor ? 15 3 2 “ 0 0

Current profile7 n/a ? n/a ? ? ? “ 0 0

Surface nutrients PO43- 0-2 µM

NO3- 0.2 µM Envirotech EcoLab8 low 18 2 ? ASIS

buoy 0 0

In-situ water sampling n/a Envirotech Aqua Monitor9 15 “ 0 0

Export flux 5 mmol N m-2 d-1 Time-series sediment trap – see Animate 18 3 “ 0 0

Mar

ine

Moo

ring

Surface PAR n/a Chelsea PAR Irradiance sensor 2 0.5 “ 0 0

1

2

Surface micromet n/a Supplied by US scientists n/a ? ? ? “ 0 0

Nutrients PO43- 0-2 µM

NO3- 0.2 µM Sampling only10 n/a - 1 1

Ship + CTD winch

0 0

Chla,T,S 0.2-0.5 µg L-1 Chelsea Mini-pack – CTD-F sensor suite ? 10 1 “ 13 2

Photosynthetic capacity 0.2-0.5 µg L-1 Chelsea Fast-tracka FRRF 40 5 2 “ 55 10

pO2 n/a Winkler (to be run by INDP?)11 3

(E) 1 3 “ 6 2

POC / PON / DOC / DON12 sampling only n/a - 1 “ 3 2 S

– C

TD

cm

easu

rem

ents

tatio

n ast

Trace metals12 sampling only n/a - 1 “ 3 2

TOTALS 480 89

2

Table 2. Infrastructure Funding scenarios

Facility

Capital and/or 2 yr running costs (£k) Ph

ase

1

Phas

e 2

Container Laboratory x 2 75 75 0 Site set-up and operation 42 42 0 Running costs of site: rent, water, food, power and communications 16 24 16

Tower, pump and sampling line 15 15 0 Security Fence 1 1 0

Atmospheric

Atmospheric equipment shipping13 8 8 0 Rosette water sampler 14 14 0 Other shipboard equipment 12 12 0 Ship overhaul and maintenance 46 46 10 Ship time (fortnightly occupations) 78 78 78

Marine

Equipment shipment 4 4 0

TOTALS 319 104

Table 3. Personnel and Travel

Personnel

Funding scenarios

as above (£k) UK SOLAS PDRA Atmospheric Instrumentation. Phase 1 = full time for 1 yr and ½ time for 2 yrs (start spine 8 46% overheads). Phase 2 = ½ time for 2 yrs 59 29.5

UK SOLAS PDRA Data manager. Full time for 1 yr and ½ time for 2 yrs (start spine 8 46% overheads).Phase 2 = ½ time for 2 yrs 59 29.5

Local site manager 2 years, CV citizen employed through INMG, 5% overheads17 17 17

1 x technician (CV citizens, employed by INMG, 5% overheads)14 . Phase 1 = 2.5 yrs, phase 2 = 2 yrs. 7 5

Atmospheric

Night security guard (Phase 1 = 2.5 yrs, phase 2 = 2 yrs)14 7 5

UK SOLAS PDRA employed through IFM-GEOMAR Start spine 8 46% overheads) 29.5 0 Marine Technician (CV citizen, employed by INDP, 5% overheads) (Phase 1 = 2.5 yrs, phase 2 = 2 yrs)14 7 5

Travel (all groups) For scientific support, training and project management 15 37 21

TOTALS 223 112

Table 4. Overall costs to UK SOLAS (£k)

PH

AS

E 1

PH

AS

E 2

Measurement 480 89Infrastructure 319 98

Personnel / travel 223 122TOTAL 1022 309

Appendix 1: 1. ANNOXA was selected for NOX determinations because of its very low detection limit (~2 ppt).

Other ‘off-the-shelf’ instruments have detection limits of around 50 ppt, unsuitable for the level expected in the Cape Verde region. The UEA NOx/y instrument was considered but would only be available for short periods of time.

2. Could also be achieved with Agilent Unity Air-Server GC-MS (£90k for NMHCs and CH4) and

Ionicon PTRMS (£90k for DMS, OVOCs and isoprene, plus also benzene, toluene and other organics).

3. To be deployed and run by Univ Heidelberg if bid to D-SOLAS is successful. 4. To be deployed and run by Dr. Harmut Hermann, University of Leipzig, with D-SOLAS or

institute funding. 5. Detailed meteorological measurements are made on the island of Sal (the next major island E of

Saô Vincente), including daily radiosondes. Although there may be some variation in the structure of the near-surface troposphere between Sal and Saô Vincente, the free troposphere is likely to be very similar at the two sites. Thus substantial cost savings can be achieved by using daily data from Sal (freely available through BADC), with fortnightly measurements at Saô Vincente to confirm agreement.

6. One set of Microcat’s. Could be used on McGillis ASIS buoy. 7. Survey indicated little interest in this measurement but will be included in ASIS mooring measurements if

deployed. 8. Measures NO3

-, NO2, NH3 and PO43-. Can also measure chla fluorescence (at extra cost).

9. Takes up to 50 samples of a maximum of 1 litre each for plankton samples and chla calibration. Samples can

be fixed with reagents automatically in-situ for other measurements. Capital costs include 3 years running costs (informal quote from Enviro-tech).

10. Does not include analysis costs, only shipping costs of samples. 11. Method can be used to calibrate pO2 measurements on mooring if deployed. 12. Costs include shipping of samples but not analysis. 13. The cost of shipping an average-sized container to Cape Verde is around £2k. The cost of a two week trip to

Cape Verde, including flights, accommodation, food and contingency, is estimated to be €2100 (£1600). 14. Costings were based on the following information from Cape Verde partners: Technician: €2850 pa (£2200);

Site manager (PhD level researcher or engineer): €10250 pa (£7900). UK-SOLAS is not expected to pay overheads on staff employed through the Cape Verde research institutes (INMG and INDP), making the above figures the full cost of employing local staff. However, project partners have agreed to make a 5% contribution to overheads for these institutes.

15. Access to the atmospheric site is expected to be via a 4x4 vehicle run by the INMG. The technicians would

be responsible for driving visiting scientists to the site, and would drive there themselves daily from Mindelo. The estimated cost of the vehicle usage and fuel is £6 per day, i.e. £2190 pa. In addition: Phase 1: over 3 years, an estimated 20 flights at £1000 ea and a total of 8 months subsistence (£300 per week) is costed. Phase 2: 10 flights at £1000 ea and a total of 5 months subsistence (£300 per week) is costed.

Appendix 1. Analysis of requirements of the UK SOLAS proposals A.1 Balance between marine and atmospheric activities PIs’ interest in the observatory is split relatively evenly between the marine and atmospheric aspects, with most respondents interested in both (Fig 4). However, it should be noted that whereas there are well-established techniques for making (land based) continuous measurements of gas-phase composition this is not the case for the water-phase. As a result, the proposed marine measurements are mostly for ‘ancillary’ parameters, such as temperature, salinity and chlorophyll a fluorescence. Quantifying causal links between marine and atmospheric systems may only be possible if aqueous phase measurements are expanded in scope (and cost), to include parameters such as trace gas and photosynthetic pigment concentrations, and microbial counts, identification and gene activity.

0

2

4

6

8

10

12

would useobservatorydata output

would useobservatory

facilities

interested inmarine

observatory

interested inatmosphericobservatory

Interest in observatory

# re

spon

ses

expr

essi

ng in

tere

st

Figure 6. Interest in various aspects of the proposed UK SOLAS Observatory by UK SOLAS PIs (12 responses). A.2 Specific measurements Figure 7 summarises PIs’ views on the desirability of specific marine and atmospheric measurements, rated by each project on the scale: 0 (no interest), 1 (peripheral interest), 2 (definite interest) and 3 (very important). The colouring of the bar shows whether a total score of - for example - 9 for a specific measurement was obtained by 3 projects giving it a score of 3, or by 9 projects giving it a score of 1. Overall, the survey results demonstrate a strong interest in almost all of the proposed measurements – with highest ratings for atmospheric DMS and aerosol parameters, and marine determinations of nutrients, PAR and chlorophyll a fluorescence. With the exception of mooring current profile, each proposed measurement received at least one ‘very important’ rating. Consequently, all parameters included in the survey are covered by the costings exercise presented in Section 5 – although this will need to be re-visited when funding decisions are made on individual proposals. Additional measurements of interest to at least some PIs included atmospheric COS and CS2 determinations; and oceanic photosynthetic pigment, phytoplankton taxonomy, DMS and DMSP measurements. More frequent occupation of the marine station (ie increase seawater sampling from fortnightly to weekly) was also considered desirable. Currently, there are no existing techniques with detection limits suitable for making continuous aqueous phase measurements of compounds like DMS or the halocarbons, nor for analysing biological samples in-situ. Two possible approaches to address this issue have been identified, but are not included in current costings: • Collect seawater samples during the fortnightly occupation of the proposed marine station, for analysis

of trace gas concentrations and biological parameters by technicians on Cape Verde. • Collect and preserve seawater samples for biological analysis, and extract/store mples for trace gas

determinations at laboratories back in the UK. Support for this approach could beinterested research groups through the 2nd funding round of UK SOLAS or possi

a. .

sab

bly ‘blue skies’ support.

(a) (b)

0 5 10 15 20 25

mooring

T,S

NO 3- / NO 2-

pH profile

current profile

surface PAR

Micromet

time series s tation

Nutrients

FRRF

Chla flour

PAR

Carbonate

DO C /DO N

Ferrybox

Nutrients

FRRF

T,S

Chla flour

Fac ilities

Water samples

Mooring Space

point score

0 5 10 15 20 25

trace gasesO zone

Carbon monoxideCarbon diox ide

Nox/yDMS

methaneN2O

NMHCsOVO Cs

Halocarbons

Dust, aerosol, prec ipitations ize seg. Aerosol. No. density

Aerosol trace metalsAerosol Major ions

prec ipitation trace metalsprec ipitation major ions

Met and physicsRadiosonde

Radiation spectrumwet+dry depos ition rates

Fac ilitiesLab space

Access to air sampling lineInstruments on tower

point score

Figure 7. PIs’ interests in (a) marine and (b) atmospheric measurements and facilities proposed for the UK SOLAS observatory. Red, green and blue bars indicate total scores for very important, definite interest and peripheral interest, respectively.