WHP Ref. No.: ISS1/ISS2/IR3
Last updated: 23 June 1995

			NOAA/AOML/PhOD Cruise Report
			Indian Ocean Repeat Hydrography

A.	 Cruise narrative

A.1.	 Highlights
a.	 WOCE designation: 	ISS1
				ISS2
				IR03
b.	 Expedition designation:3175MB95/02
				MB-95-02
c.	 Chief scientist: 	Amy Ffield
				NOAA/AOML
				PhOD
				4301 Rickenbacker Causeway
				Miami, Florida 33149, USA
				Telephone: 305-361-4582
				Telefax: 305-361-4582
				Internet: ffield@aoml.erl.gov
d.	 Ship: 			MALCOLM BALDRIGE
e.	 Ports of call: 	Durban, South Africa to Colombo, Sri Lanka
f.	 Cruise dates: 		March 21, 1995 to April 22, 1995

A.2.	 Cruise Summary Information

a.	 Geographic boundaries: The cruise took place in the Arabian Sea and 
the southwest Indian Ocean within an area bounded by 40¿S to 10¿N and 29¿E to 
64¿E. 

b.	 Stations occupied: 
Total number of stations occupied on the cruise:
CTD/O2: 	114
LADCP: 	113
XBT:         	51

c.	 Floats and drifters deployed:  Twelve drifters were deployed on the 
cruise (need deployment locations and details)

A.3.	 List of Principal Investigators

The principal investigators for all measurements are listed in Table 1.

TABLE 1:  List of principal investigators and their responsibilities

Principle Investigator	        Measurements	       Affiliation
Amy Ffield			CTD, O2, salinity	CIMAS
Doug Wilson			ADCP, LADCP		AOML
Rik Wanninkhof			pCO2, TCO2		AOML
Andrew Dickson			pH			SIO
Francisco Chavez		nitrate, chlorophyll,	MBARI
				irradiance, nutrients
Paul Quay			C-13			Univ. of Washington
Allan Devol			O2, Ar			Univ. of Washington
Tom Carsey			O3, NO2, NOx, NOy, PAN	AOML
Russ Dickerson			sonde, CO, 		University of Maryland
				photolysis rate of NO2, aerosols 	
				aerosol optical depth, surface
Lisa Ballance			ocean fauna		Southeast Fisheries

A.4.	 Scientific Programme and Methods

Physical Oceanography 
	Amy Ffield and Doug Wilson, CIMAS/AOML

The NOAA Climate and Global Change Program (C&GC) objective of measuring the 
ocean property distributions and their evolution in time coincides with the 
major objectives of the World Ocean Circulation Experiment (WOCE) to 
understand the general circulation of the global ocean well enough to be able 
to model its present state and predict its evolution. During the Indian Ocean 
field period in 1995 high resolution hydrographic surveys will be obtained by 
the NOAA Ship MALCOLM BALDRIGE along WOCE Hydrographic Program (WHP) area ISS1 
(I5W), IR03 (I7N), IR01W (I1W) and ISS2, and IR04 (I8N). In the Indian Ocean 
the major oceanographic questions are intrinsically coupled to its large 
monsoonal variability. The surveys are designed to capture the variability in 
the Indian Ocean by repeating measurements along the same WHP lines as sampled 
by the R/V Knorr in 1995. In order to sample during the opposite monsoon 
season then the Knorr, some of the BALDRIGE's repeat surveys actually precede, 
or "prepeat", the Knorr's one-time surveys.

WHP repeat section IR03 and Special Study Areas ISS1 and ISS2 were chosen to 
most efficiently capture a broad sampling of the current regimes influenced by 
the monsoons, thermohaline overturning regions, and historically poorly 
sampled thermocline and deep flows in the Indian Ocean. Together, the repeat 
and one-time WHP surveys will be used to estimate monsoonal variations of the 
thermohaline overturning, meridional and zonal flows, and heat and freshwater 
fluxes. These processes have been carefully selected as fundamental to 
increasing the understanding of the Indian Ocean's role in climate. In 
addition, the hydrographic measurements will also support NOAA CO2 
measurements for the OACES program. All together, the international effort 
will provide a data set with unprecedented coverage of the Indian Ocean and 
will serve as a reference point for future monitoring of its physical and 
chemical properties.    

Within ISS1, WHP line I5W extends from the South African coast along ~33¿S to 
55¿E with relatively sparse CTD/O2/LADCP sampling. XBTs were used along I5W in 
order to improve the sampling density. The stations near the South African 
coast span the mooring array deployed one month earlier (Bryden). The I5W line 
in the ISS1 area was previously sampled in 1987 by Toole and Warren, and will 
be resampled by the Knorr in 1995. WHP line IR03 continues north from I5W 
generally along 55o E to 8.5o N, and the typical sampling is 30 nm. Automated 
continuous measurements of position, bathymetry, sea surface parameters, and 
standard meteorological parameters complement the data set.

Several sections are presented using the preliminary current measurement data 
(Wilson). Two hundred meters was the deepest common depth along this section, 
where range was reduced due to higher sea states. The south(west)ward flowing 
Agulhas current is visible along the western boundary, with energetic 
alternating bands extending off shore. A contoured LADCP section from I5W is 
not shown due to the relatively large and uneven station spacing on this leg.  
  
Notable features include near bottom eastward flow near 27¿S, relatively weak 
South Equatorial Current and Countercurrents between 20¿ and the Seychelles at 
5¿S, and a strong, deep equatorial current system. Figure 9 shows the upper 
ocean equatorial currents at an expanded scale and highlights the favorable 
comparison between velocities measured by the lowered and shipboard ADCP 
systems. Much of the difference seen is due to interpolation between LADCP 
stations, mostly spaced at 30 to 50 kilometers.

A.5.	 Major Problems and Goals Not Achieved

Five days of the Scientific Computing System underway data may have been lost 
due to an undetected error on the backup disk; 2 of the 5 days were during 
transit and anchorage for the medivac described in the section below. Previous 
problems with the starboard side winch and narrow beam bathymetry were 
corrected before the beginning of this cruise, and they performed well 
throughout the entire cruise. All the scientific goals of the cruise were 
achieved.

A.6.	 Other Incidents of Note
Twenty-four hours were used for an emergency medivac to Mauritius. After 
medical consultation at Mauritius, arrangements were made to fly the patient 
to the US for treatment. 

