RRS Discovery D319
Cruise summary report
| Cruise Info. | |||||||||||||||||||||||||
| Ship name (ship code) | RRS Discovery (74E3) | ||||||||||||||||||||||||
| Cruise identifier | D319 | ||||||||||||||||||||||||
| Cruise period | 2007-05-19 — 2007-06-11 | ||||||||||||||||||||||||
| Status | Completed | ||||||||||||||||||||||||
| Port of departure | Lisbon, Portugal | ||||||||||||||||||||||||
| Port of return | Falmouth, United Kingdom | ||||||||||||||||||||||||
| Purpose | Research | ||||||||||||||||||||||||
| Objectives | Objectives: To quantify marine halocarbon emission variability and latitudinal variation, characterise in situ open ocean atmospheric reactive iodine latitudinal variability and characterise oxidative chemistry perturbation due to oceanic emission of halogens from the Mauritanian upwelling region.
Rationale: Transecting from the UK through Biscay, south past the west coast of Africa, through the Mauritanian upwelling, to pass Cape Verde simultaneous to the intensive deployment at the UK SOLAS Observatory on Sao Vicente, the measurements made on Discovery cruise D319 are intended to provide a detailed latitudinal characterisation of marine atmospheric halogen chemistry. This will feed validation and constraint data to regional and global models in projects linked to RHaMBLe. In addition the cruise will address a number of key scientific questions required to determine the global importance of iodine chemistry and to further our understanding of the controls of halogen chemistry in the remote ocean: i) How heterogeneous are the direct halogen sources and on what scale is the heterogeneity - does the upwelling region produce more or less halogens than the 'background' region? ii) What are the relative contributions of I atoms to the remote MBL from I2 and organic iodine? iii) Is sufficient iodine released to the remote MBL to sustain aerosol nucleation or to significantly affect the ozone budget and free radical populations? Measurement Description: Measured species included a variety of halocarbons in both water column and atmosphere and atmospheric boundary layer measurements of I2, OIO and IO by Broadband Cavity Enhanced Absorption Spectroscopy (BBCEAS). A compact version of the FAGE system, developed for the FAAM BAe-146, was deployed to provide measurements of IO or OH / HO2, permitting direct assessment of RHS-induced changes in the oxidising environment through the upwelling region. A range of trace gas monitors was simultaneously deployed to measure O3 and NOx. Aerosol number and size distribution measurements from 3 nm to 20 micron diameter were also made by a range of mobility (SMPS) and optical instrumentation, (OPC and FSSP). Additional aerosol measurements were provided as part of the NERC-funded ACMME project (PI Allan). Measurements of pigments in the surface waters were made by HPLC. Prevailing meteorological conditions were used to direct the cruise in terms of geographical positioning and measurement interpretation, e.g. i) exploitation of any broad flow connection between Cape Verde and the ship to interpret measurements as process studies and ii) identification of in- and out-of-plume conditions to contrast chemistry influenced and uninfluenced by emissions from the upwelling region. | ||||||||||||||||||||||||
| Chief scientist | Gordon B McFiggans (University of Manchester School of Earth Atmospheric and Environmental Sciences) | ||||||||||||||||||||||||
| Project | UK SOLAS | ||||||||||||||||||||||||
| Coordinating body | NERC | ||||||||||||||||||||||||
| Cruise report |  (1.43 MB) | ||||||||||||||||||||||||
| Ocean/sea areas | |||||||||||||||||||||||||
| General | North East Atlantic Ocean (limit 40W) | ||||||||||||||||||||||||
| Specific | North Atlantic Ocean | ||||||||||||||||||||||||
| Track charts | (0.09 MB) | ||||||||||||||||||||||||
| Measurements | |||||||||||||||||||||||||
| Chemical oceanography | |||||||||||||||||||||||||
| Other chemical oceanographic measurements | Quantity: number of samples = 120 Description: Purge and trap measurements of halocarbons in seawater samples by Perkin-Elmer Turbomass GC - quadrupole mass spectrometer coupled to Perkin-Elmer Turbomatrix thermal desorption units (approximately every 2-2.5 hours, with 16-20 hour coverage each day). | ||||||||||||||||||||||||
| Biology and fisheries | |||||||||||||||||||||||||
| Phytoplankton pigs (eg chlorophyll, fluorescence) | Description: Determination of photosynthetic pigments (abundances and distributions) in seawater samples collected from the non-toxic supply, by high performance liquid chromatography (not RHaMBLe-funded). | ||||||||||||||||||||||||
| Phytoplankton | Quantity: number of samples = 45 Description: Seawater samples collected and filtered for phytoplankton counting periodically (between 1 and 6 times a day) to coincide with water sample analyses for halocarbons. Phytoplankton counts will be determined following post cruise analysis | ||||||||||||||||||||||||
| Meteorology | |||||||||||||||||||||||||
| Incident radiation | Description: Measurements of solar irradiance intensity to enable calculation of photolysis frequencies of atmospheric compounds by 2 spectral radiometers (not RHaMBLe-funded). | ||||||||||||||||||||||||
| Atmospheric chemistry | Description: Measurement of the concentration of atmospheric iodine monoxide (IO) radicals by the FAGE technique using Laser Induced Fluorescence (LIF). An all solid-state Nd:YAG pumped Ti:Sapphire laser operating at approximately 445 nm was used to excite the (2,0) band of the IO A2П3/2←X2П3/2 electronic transition, with off-resonance fluorescence in the (2,5) band detected at 521 nm. | ||||||||||||||||||||||||
| Atmospheric chemistry | Quantity: number of profiles = 1 Description: Measurements of the concentration of atmospheric iodine monoxide (IO) and nitrate (NO3) radicals by broadband cavity enhanced absorption spectrometer (BBCEAS) using absorption bands between 420 and 480nm for IO and between 620-680nm for NO3. The instrument was run continuously between periodic re-alignment and calibration for the majority of the cruise. | ||||||||||||||||||||||||
| Atmospheric chemistry | Quantity: number of profiles = 1 Description: Measurements of the concentration of the atmospheric molecular iodine (I2)by broadband cavity enhanced absorption spectrometer (BBCEAS) using absorption bands between 520 and 560nm. The instrument was run continuously between periodic re-alignment and calibration for the majority of the cruise. | ||||||||||||||||||||||||
| Atmospheric chemistry | Quantity: number of profiles = 1 Description: Continuous automated measurements of the atmospheric concentrations of halocarbons by Perkin-Elmer Turbomass GC - quadrupole mass spectrometer coupled to Perkin-Elmer Turbomatrix thermal desorption unit. 24 hour coverage, sample frequency of 70 minutes from 21/05/07 to 07/06/07 | ||||||||||||||||||||||||
| Atmospheric chemistry | Quantity: number of profiles = 1 Description: Measurement of the concentration of atmospheric NO, NO2 and O3 using 2 x Eco Physics NO analysers (type CLD780) with chemiluminescence detectors and an Eco Physics Photolytic Converter to convert NO2 to NO for one instrument. For O3 a 2B Technologies O3 analyser was used. | ||||||||||||||||||||||||
| Atmospheric chemistry | Description: Various offline chemical analyses from samples taken using compact cascade impactor (CCI) and 2 Andersen high-volume cascade impactors. Particles are separated aerodynamically according to size (into nstage samples) varying from daily to one per several days (not RHaMBLe-funded). | ||||||||||||||||||||||||
| Atmospheric chemistry | Description: The non-refractory components of ambient aerosol particles (nitrate, sulphate, organic matter and ammonium) between around 40 and 700 nm diameter were quantified using an Aerodyne time-of-flight aerosol mass spectrometer (AMS). Aerodynamic sizing allows this data to be collected in a size-resolved manner and the additional information on the organic fraction can be obtained through inspection of the mass spectra. Mass loadings for nspec = 4 chemical species reported every 10 minutes, Mass distributions less frequently (not RHaMBLe-funded). | ||||||||||||||||||||||||
| Other meteorological measurements | Description: Measurement of the size changes that occur within submicron particles when exposed to high (90%) humidity by hygroscopicity tandem differential mobility analyser (HTDMA). Particles are dried, electrostatically selected according to size, humidified, then sized a second time before being counted using a condensation particle counter. Full hygroscopic growth factor distributions are reported every hour (not RHaMBLe-funded). | ||||||||||||||||||||||||
| Other meteorological measurements | Description: Estimation of the concentration of black (elemental) carbon using a Thermo Electron multi angle absorption photometer (MAAP) to collect ambient aerosols onto a filter tape and measures the optical absorbance reported at 10 minute intervals (not RHaMBLe-funded). | ||||||||||||||||||||||||
| Other meteorological measurements | Description: The number concentration of potential cloud particle seeds for a given supersaturation was counted using a Droplet Measurement Technologies cloud condensation nuclei (CCN) counter. On alternate hours, the instrument samples particles of specific sizes from the dry differential mobility particle spectrometer, allowing the cloud condensation nuclei concentration to be delivered as a function of dry particle size. A full CCN spectrum is reported hourly (not RHaMBLe-funded). | ||||||||||||||||||||||||
| Other meteorological measurements | Description: Measurement of the size-resolved concentration of coarse atmospheric aerosol particles (>600nm ) using 2 GRIMM optical particle counters. Continuous measurement reported at 10 minute intervals in nbin = 12 bins. | ||||||||||||||||||||||||
| Other meteorological measurements | Description: Measurement of the size-resolved concentration of fine atmospheric aerosol particles by differential mobility particle sizers (DMPS) separating particles by electrostatic selection according to size before counting with condensation particle counters, measuring the number and size of particles between 3 and 800 nm. In one instrument, the particles are dried, the other is operated at ambient (~85%) humidity. Continuous measurement reported at 10 minute intervals in approx. nbin = 50 bins. | ||||||||||||||||||||||||
| Other meteorological measurements | Description: Measurements of the aerosol generated from seawater (from either the clean water 'fish' or the ship's non-toxic inlet) were made by flowing air continuously through a bubble tank using a peristaltic pump to flow a water jet onto the water surface in the tank, creating bubbles and generating particles, which are delivered to sizing, composition & property determination instrumentation. Number of useable experiments small but unknown (not RHaMBLe-funded). | ||||||||||||||||||||||||
| Data held at BODC | Get data | ||||||||||||||||||||||||
| Series/Profiles | |||||||||||||||||||||||||
| 5 Pumped air sample | Reference numbers Horizontal spatial co-ordinates Date and time Atmospheric particulates
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| Discrete samples | |||||||||||||||||||||||||
| 238 Atmospheric air sampling pump | Concentration of inorganic halogens in the atmosphere | ||||||||||||||||||||||||
| 15 Cascade impactor atmospheric sampler | Sulphur species concentrations in the atmosphere Metal concentrations in the atmosphere Concentration of nitrogen species in the atmosphere Concentration of inorganic halogens in the atmosphere | ||||||||||||||||||||||||
| 118 Sample taken from ship's non-toxic supply | Salinity of the water column Other halocarbon concentrations in water bodies |
