Ship cruise measurements

In this work we compare some of the major results from two field expeditions to the Southern Ocean region. The first expedition was a ship cruise between Punta Arenas/Chile and the west coast of the Antarctic Peninsula, which was conducted during the austral fall season (March 20 - April 28, 1986) as part of the United States Antarctic Research Program (USARP). Details of the ship cruise and a complete discussion of the results have been published elsewhere (12). The second expedition consisted of a series of flight measurements off the west and south coast of Tasmania during the austral summer season (December 3-18, 1986). We discuss preliminary results from 2 of 8 flights which were conducted in marine air masses behind cold fronts moving over the open ocean. 

Our data obtained from both the ship cruise (Table II) and the flight measurements (Figure 3) suggest that photooxidation of DMS in the Southern Ocean atmosphere leads to a higher yield of MSA and a lower yield of SO2 compared to other world ocean areas. We conclude that these yields are possibly a function of latitude and altitude and, basically, of temperature as suggested by the recent laboratory studies of Hynes et al. (21). 

The measurement program has two components, long-term and intensive. For the long-term component, data collection to determine the composition of wet deposition at Lewes, Delaware, and on Bermuda began in 1980. In 1984, another site was added at Adrigole, Ireland. From 1981 to 1985 during May-October, precipitation samples were also collected on two ships cruising weekly between New York City, Bermuda, and Nassau. Precipitation-chemistry data from the three land-based sites and from the ships were used to calculate... 

The instrument constant B can be determined by measuring the t in two fluids of known density. Air and water are used by most workers (22). In our laboratory we used seawater of known conductivity and pure water to calibrate our vibrating flow systems (53). The system gives accurate densities in dilute solutions, however, care must be taken when using the system in concentrated solutions or in solutions with large viscosities. The development of commercial flow densimeters has caused a rapid increase in the output of density measurements of solutions. Desnoyers, Jolicoeur and coworkers (54-69) have used this system to measure the densities of numerous electrolyte solutions. We have used the system to study the densities of electrolyte mixtures and natural waters (53,70-81). We routinely take our system to sea on oceanographic cruises (79) and find the system to perform very well on a rocking ship. 

The concentration term for DMS (S) is calculated using the mean of the average DMS concentrations found on cruises between April to September and is equal to 8.8 nmol DMS (S) H. Air concentrations are of the order of 3 nmol DMS (S) nr3 (1) and are assumed to be negligible, hence the concentration difference is equal to the mean DMS concentration in water. The transfer velocity, k, was calculated from the equations of Liss and Merlivat (14) using the mean wind speeds measured on board ship, which procedure yields a value of 15.4 cm h 1. Therefore DMS emission is equal to ... 

Salt Aerosol Observations. The average salt aerosol concentration for the entire cruise was 21.7 30.9 /xg/m (arithmetic mean and standard deviation, respectively, for 253 samples from the ARCAS). Salt aerosol concentrations were also measured by Prospero 16) from ships in the South Atlantic Ocean at an elevation of 15 m. His overall statistics for 35 samples taken in the tropical and central South Atlantic (5° S to 35° S) are 9.1 5.3 jLtg/m. When he includes five additional samples collected near the Cape of Good Hope, these values become 11.3 9.2 /xg/m. A higher salt... 

The forerunners of the later standardized seasonal cniises started in May 1955 with synchronous measurements by the r/v Joh. L. Kruger and the r/v Magnetologe between the Fehmarnbelt and the Bornholm Basin. Finally, the programme of seasonal cruises had started in August 1957. It included about 50 fixed stations and comprised the combination of longitudinal and transversal sections between the Fehmarnbelt and the Bornholm Basin. More diurnal anchor stations each in the Fehmarnbelt and in the southern entrance of the Sound were included for investigations on temporal variabilities. The parameters measured were temperature, salinity, and oxygen at fixed depths. At some stations, current measurements were carried out from the anchored ship (cf. Section 3.2.1). 

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