29 
5.1. Differences in water mass characteristics 
Potential temperature-parameter diagrams provide a good tool to document differences in 
water mass characteristics in both climatologies (Fig.15) . Lozier et al. (1994) were first to 
demonstrate the production of artificial water masses in the first World Ocean climatology by 
S.Levitus (1982) if averaging of the observed data is performed on isobaric surfaces. They 
also recommended to use an isopycnal averaging of the data in order to retain the observed 
thermohaline structure in the gridded (averaged) data. Gouretski and Jancke (1999) 
compared observed high quality hydrographic data in the South Pacific both with the 
WOA94 climatology and with their isopycnically averaged climatology. They found that 
WOA94 climatology produces artificial water masses within the central Ross gyre and along 
the Antarctic Circumpolar Current because of using an isobaric averaging of the data. It was 
also found, that the WOA94 climatology does not reproduce characteristic high-salinity shelf 
waters in the Pacific sector of the Southern Ocean. 
Temperature difference WOCE - WOAOl at 500 m depth 
I I I I I I I I I I I I I I I I I 
-180 -160 -140 -120 -100 -80 -60 -40 -20 0 20 40 60 80 100 120 140 160 180 
Longitude 
3.00 -0.75 -0.50 -0.25 0.00 0.25 0.50 0.75 8.00 
Salinity difference WOCE - WOAOl at 500 m depth 
-180 -160 -140 -120 -100 -80 -60 -40 -20 0 20 40 60 80 100 120 140 160 180 
Longitude 
■8.40 -0.09 -0.06 -0.03 0.00 0.03 0.06 0.09 8.40 
Fig. 17a: Temperature and salinity differences (WGHC-WOA01) 
for the 500 m depth level.