WHP Ref. No.: AR19 (A2)
Last updated: 7 September 1994

Cruise Report - AR19

A.	Cruise narrative
A.1.	Highlights
a.	WOCE designation: 	AR19 (repeat equivalent of A2)
b.	Expedition designation:	06GA226/1
				06GA226/2
c.	Chief scientist:	Alexander Sy, BSH
d.	Ship: 			R/V Gauss
e.	Ports of call: 		Leg 1: Hamburg to Halifax, Nova Scotia
				Leg 2: Halifax to Hamburg, Germany
f.	Cruise dates: 		Leg 1: June 12 to June 30, 1993
				Leg 2: July 4 to July 31, 1993

A.2.	Cruise Summary Information

a.	Geographic boundaries: 
	48N - English Channel to Newfoundland

b.	Stations occupied: 
	46 XCTD casts to 1000 m (leg 2)
	114 XBT casts to 2000 m (leg 2)
	75 CTD/rosette stations (leg 1)

c.	Floats and drifters deployed:  
Ancillary work included the deployment of 10 surface drifters in the North 
Atlantic Current. On July 8 and 9 all 10 surface drifters were deployed along 
the section between 42'55.4°N, 48'05°W and 42'22°N, 46'16.4°W.

d.	 Moorings deployed or recovered: 
A total of five full-depth moorings off the Irish Shelf and west of the Mid 
Atlantic Ridge (MAR) were deployed. Full-depth, long-time moorings were 
deployed at the following locations:

	Name	Date	  Position
	G1	June 16	  48'56.0°N  12'56.4°W
	G2	June 17	  48'50.0°N  13'59.9°W
	Kl	June 20	  46'21.7°N  29'59.3°W
	K2	June 21	  45'56.4°N  31'49.0°W
	K3	June 22	  45'20.4°N  33'15.7°W

A.3.	List of Principal Investigators

Measurement	Principal Investigator	Institution

Salinity	A. Sy and H. Bartmuss	BSH
Oxygen		A. Sy			BSH
Nutrients	D. Machoczek		BSH
CTD/O2		P. Koltermann		BSH
TSG		D. Machoczek		BSH
XBT/XCTD	A. Sy			BSH
Meteorology	A. Sy			BSH
Bathymetry	Surveying group		BSH
Moorings	A. Sy			BSH
Drifters	G. Stelter and Krauss	BSH/IfMK

A.4.	Scientific Programme and Methods

Cruise # 226 by R.V. "Gauss" (call sign: DBBX) was a contribution by 
Germany's Bundesamt fur Seeschiffahrt und Hydrographie (BSH) to the World 
Ocean Circulation Experiment (WOCE) Hydrographic Programme within the German 
research programme METRANA (Meridional Transports in the North Atlantic). The 
cruise began on June 12 in Hamburg and finished there on July 31, 1993. The 
scientific objectives of the cruise were to carry out a CTD [WHP section AR19 
(A2)] and a high density XBT/XCTD survey (VOS line AX-3) from the Irish Shelf 
to the Newfoundland Shelf. Sampling along the AR19 hydrographic section was 
designed to meet the WOCE requirements for repeat surveys. "Gauss" cruise 226 
was successful and the data quality is good. The captain of the vessel on leg 
1 was Walter Fietz and on leg 2 Klaus-Peter Walde.

The hydrographic section was to measure thq northward flow of the North 
Atlantic Current and the southward recirculation. The cruise aims to improve 
the scientific knowledge of the distribution and sources of water masses, and 
their flows, velocities and patterns by obtaining high-accuracy measurements 
of temperature, salinity and dissolved oxygen and nutrient content. These 
data will be used to estimate geostrophic velocities and transports, and to 
map water mass properties with which the circulation over the entire depth, 
particularly of the deep basins, can be deduced.

Besides providing estimates of the water mass characteristics, their 
spreading paths and mixing history as a snap-shot in summer 1993, the data 
from this cruise are to be compared with historic data sets and with future 
repeats to determine long-term changes in these properties. Furthermore, the 
transport estimates from the Deep Western Boundary Current array and other 
current meter arrays will be used to calculate the meridional transports of 
heat, salt and freshwater through this section as well as changes in these 
parameters. XBT and XCTD data will be used as a supplement to a high density 
Ship-of-Opportunity programme run by the BSH since 1988.

CTD station work on the AR19 hydrographic section began on July 8, 1993, 
01:00 UTC at 43.5°N, 50°W and was completed on July 25, 14:00 UTC at 49'
14°N, 10'40°W (Fig. 1 b). 75 stations were occupied along the section. At 
each station the vertical distribution of temperature, salinity, dissolved 
oxygen content and nutrient content (NO3, SiO3 and P04) was obtained using a 
continuously measuring CTDO2-sonde as well as water samples from discrete 
depths. All CTD profiles were distributed worldwide in near real-time via 
GTS. For test purposes, 8 CTD profiles were measured before and after the 
main section work. 

CTD data processing is under way and will be finished in summer 1994. The 
data quality is good and is expected to meet the WOCE requirements. All 
bottle data were analysed on board except nutrients. Nutrient samples were 
stored in a refrigerator until analysis at AWI (Alfred-Wegener-Institut fur 
Polar und Meeresforschung, Bremerhaven, Germany).

The CTD section reveals considerable changes in the water mass 
characteristics at intermediate depths since the early 1980s. Labrador Sea 
Water (LSW) with its clear oxygen and salinity signal was now found at depths 
of more than 2000 m in the western basin; its core temperature was about 3.2°C.
Compared to the last section of comparable quality, worked by the 
Canadian-CCS "Hudson" on cruise 82-002 in April 1982, the LSW properties in 
the western basin are markedly different (Fig. 3). Most conspicuous is the 
depth of LSW east of Newfoundland that increasedby 700 m from about 1400 m in 
1982 to more than ~2100 m in July 1993. The temperatures are 0.4 to 0.5°C 
cooler, and salinities are only slightly lower, by less than 0.01.

The decrease in changes when crossing the Mid Atlantic Ridge into the eastern 
basin is also remarkable. Immediately east of the MAR, the LSW is found 
almost at the same depths of about 1800 m as in 1982; the temperatures are 
some 0.1°C cooler and salinities have decreased by about 0.01 to 0.02.

A.5.	 Major Problems and Goals Not Achieved

No serious technical problems arose and no heavy weather interrupted the 
station work.

A.6.	 Other Incidents of Note
None noted.


