Metadata Report for BODC Series Reference Number 953317

• Metadata Summary

• Problem Reports

• Data Access Policy

• Narrative Documents

• Project Information

• Data Activity or Cruise Information

• Fixed Station Information

• BODC Quality Flags

• SeaDataNet Quality Flags

Metadata Summary

Problem Reports

No Problem Report Found in the Database

Data Quality Report

No problems with data quality were reported by the data originator, or identified by BODC.

Data Access Policy

Public domain data

These data have no specific confidentiality restrictions for users. However, users must acknowledge data sources as it is not ethical to publish data without proper attribution. Any publication or other output resulting from usage of the data should include an acknowledgment.

The recommended acknowledgment is

"This study uses data from the data source/organisation/programme, provided by the British Oceanographic Data Centre and funded by the funding body."

Narrative Documents

GRIMM 1.108 Aerosol Spectrometer

The GRIMM 1.108 Aerosol Spectrometer is a small, portable unit used for the continuous measurement of aerosols. Measurements are determined in either particle counts per unit volume, or mass per unit volume.

Ambient air is drawn into the instrument by a volume controlled pump, at 1.2 L min^-1. Particles are size classified by a Differential Mobility Analyser (DMA), then counted by an Optical Particle Counter (OPC). The DMA neutralises the electrostatic charges of incoming particles, then imparts a charge to them. In the electrical field of the classifier, the particle trajectory is determined by the charge/mass ratio. Only particles within a narrow size range have the trajectory to exit the classifier to the OPC. As sequential size classes are counted, they are deposited on a 47 mm PTFE filter. The entire sample is deposited on the filter, which may be removed for subsequent gravimetric or chemical analysis.

Instrument specifications

Physical parameters

Further details can be found on the manufacturer's website.

Instrument Description

Manchester Centre for Atmospheric Science (CAS) Differential Mobility Particle Sizer (DMPS)

The Manchester Centre for Atmospheric Science (CAS) Differential Mobility Particle Sizer (DMPS) measures aerosol particle size distributions. The instrument comprises two differential mobility analysers (DMA, Winklmayer et al., 1991), each with a condensation particle counter. Each DMA-CPC pairing is equipped to select particles within a different size range: ultrafine 3.4-34 nm; standard 30-830 nm. The DMA selects charged particles for detection as a function of their mobility in an electric field. Successive size fractions are counted by CPC. The DMPS returns a size/particle count spectrum every 10 minutes during sampling.

The ultrafine DMA is attached to a TSI 3025A ultrafine CPC (particle detection limit 50% at 3 nm). The standard DMA is attached to aTSI 3010 CPC (particle detection limit 50% at 10 nm).

References

Winklmayer W., Reischl G.P., Lindner A.O., Berner A., 1991. A new electromobility spectrometer for the measurement of aerosol size distributions in the size range from 1 to 1000 nm, Journal of Aerosol Science, 22, 289-296.

Instrument Description

GRIMM Optical Particle Counter

A GRIMM Optical Particle Counter (OPC) was used to resolve coarse aerosol particles. The GRIMM OPC, model 1.108, optically sizes particles in the range 0.3 µm to 20 µm. The instrument produces a particle size histogram every 6 seconds, using the intensity and angle of scattered light to size the particles.

Aerosol Properties Sampling

The University of Manchester deployed a suite of instruments to measure aerosol properties on D319. Wet and dry aerosol size spectra were measured by a combination of Differential Mobility Particle Sizers and an Optical Particle Counter. Online aerosol particle composition was determined by Aerodyne Aerosol Mass Spectrometer, and by Multi Angle Aerosol Photometer. Aerosol particle growth factors were measured by a Hygroscopicity Tandem Differential Mobility Analyser. A combination of samplers was used for the offline analysis of aerosol particle composition: a four stage Harvard compact cascade impactor, and an Anderson high-volume sampler.

Atmospheric aerosols were sampled throughout the D319 cruise through a 10 m vertical inlet stack mounted on the forecastle deck. Air was drawn in though a 2.5 µm cutoff cyclone, and distributed to the instruments listed above through a horizontal manifold, using isokinetic sampling ports.

BODC Data Processing

Data were received by BODC in tab separated ASCII format (D319_ambient_aerosol_dist_v1_1.txt). This file included date and time, aerosol size spectra, and three derived parameters: aerosol total number concentration; aerosol total surface area concentration; and aerosol total volume concentration. The derived parameters were calculated as sums across all size bins, assuming spherical particles of diameter equal to the middle of the range for that bin. The derived parameters have not been banked in the BODC database, but the original data file containing these variables is available on request.

No position data were supplied with the DMSP data. Latitude and longitude position were merged into the data file, by BODC, from the screened and processed cruise navigation file, matching on time.

Bin sizes were defined in a separate file: Aerosol_d_bins_v1.txt. The file specified lower and upper bounds for each size category. There were 64 size bins, between 10 nm and 10000 nm, evenly distributed in log diameter space. Note that the BODC parameter is defined by its upper bound only. The lower bound for each bin is the upper bound of the next, smaller, size category, or zero nm in the case of the smallest size category.

Parameter codes defined in the BODC parameter dictionary were mapped to the variables as follows:

The data were banked according to BODC standard procedures for series data. Once tagged with the appropriate parameter code, the data were loaded into BODC Series Database.

Originator's Data Processing

Two differential mobility particle sizers (DMPS) were run in parallel during the deployment: one maintained ambient humidity, while the other analysed air samples dried to < 20% relative humidity.

The "wet" DMPS maintained air at ambient humidity (aproximately 80%) and was used in combination with a separate optical particle counter (OPC, Grimm Aerosol Technik GmbH & Co. KG model 1.108, Ainring, Germany). The OPC was used to measure coarse particles, which would otherwise have been lost due to the sampling process. In order to minimise losses of coarse particles, and to maintain ambient temperature and humidity, the OPC was located close to the inlet stack.

The wet DMPS was calibrated prior to the cruise, using NIST traceable Polystyrene Latex Spheres (PSL) standard. The data submitted to BODC had already been corrected according to this calibration.

Further details of sampling strategy and methodology for this, and other D319 data sets, are available from the D319 cruise report, and from Allan et al. (2009). A detailed decription of wet and dry DMSP, and the interpolation between OPC and wet DMPS is given by Williams et al. (2007).

References

Allan J.D., Topping D.O., Good N., Irwin M., Flynn M., Williams P.I., Coe H., Baker A.R., Martino M., Niedermeier N., Wiedensohler A., Lehmann S., Muller K., Herrmann H., McFiggans G., 2009. Composition and properties of atmospheric particles in the eastern Atlantic and impacts on gas phase uptake rates, Atmospheric Chemistry and Physics, 9, 9299-9314.

Williams P.I., McFiggans G., Gallagher M.W., 2007. Latitudinal aerosol size distribution variation in the Eastern Atlantic Ocean measured aboard the FS-Polarstern, Atmospheric Chemistry and Physics, 7, 2563-2573.

Project Information

UK SOLAS, Reactive Halogens in the Marine Boundary Layer (RHaMBLe)

This project was run by the University of Manchester, aiming to quantify the impacts of marine halogens on atmospheric composition. Emphasis was placed on the roles of halogens in oxidative processes, and on aerosol formation and transformations. Observations were made of a range of reactive halogen species in the marine atmosphere.

Fieldwork included open ocean and coastal campaigns:

• Intensive field campaign at the Cape Verde observatory
• Simultaneous ship transect through the Mauretanian Upwelling region (D319)
• Coastal field project to diagnose links between particle formation and reactive halogen species

These observations provide a comprehensive characterisation of halogen compounds in the marine atmosphere. New understanding of halogen chemistry enables development of parameterisations for model tuning. RHaMBLe has extensive links with UK SOLAS funded projects, and with other UK and internationally funded projects.

More detailed information on this project may be found in the official cruise report for the RHaMBLe cruise, D319.

Weblink: http://www.nerc.ac.uk/research/programmes/solas/

Surface Ocean Lower Atmosphere Study

The Surface Ocean-Lower Atmosphere Study (SOLAS) is an international research initiative comprising over 1500 scientists in 23 countries. Its central goal is to understand the biogeochemical-physical interactions between the ocean and atmosphere, and how their coupling affects, and is affected by climate change.

UK Surface Ocean Lower Atmosphere Study

The UK Surface Ocean Lower Atmosphere Study (UK SOLAS) is the UK's contribution to the international SOLAS programme.

UK SOLAS formed interdisciplinary teams to address three primary aims

• To determine the mechanisms controlling rates of chemical transfer and improve estimates of chemical exchanges
• To evaluate the impact of these exchanges on the biogeochemistry of the surface ocean and lower atmosphere and on feedbacks between the ocean and atmosphere
• To quantify the impacts of these boundary layer processes on the global climate system

UK SOLAS started in 2003, to run for seven years. The programme was funded by the Natural Environment Research Council.

Funded projects

In total, 19 projects have been funded by UK SOLAS, over four funding rounds.

UK SOLAS has also supported ten tied studentships, and two CASE studentships.

Fieldwork

UK SOLAS fieldwork has included eight dedicated research cruises in the North Atlantic Ocean. Continuous measurements were made aboard aboard the Norwegian weather ship, Polarfront, until her decommission in 2009. Time series have been established at the SOLAS Cape Verde Observatory, and at the Plymouth Marine Laboratory L4 station. Experiments have taken place at the Bergen mesocosm facility.

A series of collaborative aircraft campaigns have added complementary atmospheric data. These campaigns were funded by UK SOLAS, African Monsoon Multidisciplinary Analyses (AMMA-UK), Dust and Biomass Experiment (DABEX) and the Facility for Airborne Atmospheric Measurements (FAAM).

Weblink: http://www.nerc.ac.uk/research/programmes/solas/

Data Activity or Cruise Information

Cruise

Complete Cruise Metadata Report is available here

Fixed Station Information

No Fixed Station Information held for the Series

BODC Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

SeaDataNet Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle: