Data Trawler - Project details

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Project details

Title: Atmospheric underway measurements
Id: 2521
Investigator(s): Melita Keywood
CSIRO Oceans & Atmosphere - Aspendale [details]

Description: The scientific objective of this work is to investigate the chemical composition, size distribution, optical properties and cloud nucleating properties of marine aerosol over the southern hemisphere with the aim of quantifying regional contributions of aerosols to radiative forcing. There is currently very large uncertainty associated with the direct, semi-direct and indirect effect of aerosols on radiative forcing. A key feature in this regard is the influence on cloud properties of cloud condensation nuclei (CCN), the very small atmospheric aerosol particles necessary for the nucleation of every single cloud droplet. A recent analysis of the 35-year CCN concentration record at Cape Grim challenges the current accepted wisdom of the role of dimethyl sulfide (DMS) on CCN formation over the Southern Ocean. In particular, it appears that DMS oxidation is only significant during the summer months at Cape Grim, and in fact other sources and processes dominate throughout the rest of the year (Gras pers com). That other sources and processes may be significant in CCN production and modulation has also recently been suggested in a review of the CLAW hypothesis. The identity of these sources remains an open question. The work proposed here will be a positive step in addressing this question. Instrumentation will run continuously in the Aerosol and Air Chemistry Labs whilst underway with no special requirements with regards to the vessel’s course or speed. On board work will involve the daily checking of instruments within the two labs and the storing of filter samples in the walk-in freezer. In addition measurements will be taken at sea using hand held instruments outside on deck during good weather conditions.
Years: 2016



List of surveys that this project was on.

Use [details] link to view survey details (map, reports, metadata etc) including links to download data.

Survey InvestigatorDescription

B. Sloyan (CSIRO, O&A) RV Investigator research voyage in2016_v03. Titled Monitoring Ocean Change and Variability along 170oW from the ice edge to the equator This voyage involves two legs from Hobart to Wellington(NZ) and Wellington(NZ) to Lautoka(Fiji). Voyage objectives of the major project - Monitoring Ocean Change and Variability along 170oW from the ice edge to the equator are: The primary voyage objective is to obtain repeat occupations of the 155 full-depth CTD and Niskin casts along the GO-SHIP P15S section, with chemistry performed on water collected at 36 bottle levels. We will measure temperature, salinity, pressure, oxygen, fluorometry, shear and micro-scale temperature continuously, and the major nutrients, oxygen, salinity, CFC and carbon components discretely via chemical analysis on board. Small amounts of material will be filtered and stored for genomic analyses back on land. CSIRO has completed this line twice before and international groups have completed similar work along lines further east. The work plan and timings are based on these past voyages. Argo float deployments will also be carried out - usually when just leaving a CTD station (SOCCOM floats) or during transit (we may slow the ship speed slightly). These will be over the ship's stern (preferred). Voyage objectives of the supplementary project -Facing the challenges of under-ice for autonomous navigation are: Accurate navigation under both drift and stationary ice is one of the key unanswered questions in polar marine science and engineering. The primary aims of this project are to (1) estimate INS drift and calibration times; and, (2) test the integration of acoustic positioning methods in an INS within a drifting and rotating frame of reference. This project will develop error propagation models at increasing latitudes and test the use of a non-stationary, ship borne acoustic positioning network on a small (<3 m) AUV. Both are critical for robust, accurate and reliable AUV operation under-ice. The primary voyage objective is make measurements of inertial drift during vessel transit and calibration time while the Investigator is on station across as broad a range of latitudes as possible. The way that this will be achieved is that, while the vessel is on station, bench top tests will be conducted for alignment. Then, while moving, tests of inertial drift will be conducted. The student on board will work with the other PIs on board to coordinate timings of these tests but will not disrupt the other work taking place on board. The work plan and timing is based on methodologies established during past voyages. Full details can be found in the in2016_v03 voyage plan. Previous MNF voyages include RV Franklin FR 05/2001 and RV Southern Surveyor SS200901.
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