Primary productivity and its regulation in the equatorial Pacific during and following the 1991–1992 El Niño

Primary productivity and its regulation in the Arabian Sea during 1995

“…In agreement with Longhurst (1998), Radhakrishna et al (1978), Nair and Pillai (1983) and Jochem et al (1993) report mean values around 60 mmol C m\ d\ for the NE Monsoon and Intermonsoon periods; and, while 60 mmol C m\ d\ is low compared to SW Monsoon primary productivity values, it is high relative to other areas of the tropical and temperate ocean (Barber et al, 1996;Karl et al, 1996). For example, the tropical Paci"c Ocean in 1992 had mean values of 29 mmol C m\ d\ north and south of the equatorial zone, and even the enriched equatorial Paci"c zone of 103N } 103S had a mean of only 52$7 mmol C m\ d\ (Barber et al, 1996). Thus Longhurst's (1998) 60 mmol C m\ d\ prediction is a relatively high level of productivity for an o!shore region that was considered to be oligotrophic for the non-SW Monsoon period of the year (Smith, 1991).…”

“…9 and 10). P in the "lament was 14.72 mmol C mg Chl a\ d\ (Table 2), a value considerably higher than those observed during EqPac (Barber et al, 1996), NABE (Chipman et al, 1993) or the Southern Ocean (Smith et al, in press). Clearly, the "lament supported both high speci"c rates and high biomass accumulation.…”

“…The in situ procedure used in the US JGOFS Arabian Sea Expedition is similar to those used by Karl et al (1990) in the Hawaiian Ocean Time Series (HOT), Lohrenz et al (1992) and Malone et al (1993) in the Bermuda Time Series (BATS), Chipman et al (1993) and Martin et al (1994) in the North Atlantic Bloom Experiment (NABE), Welschmeyer et al (1993) in the Subarctic Paci"c Ecosystem Research (SUPER) project, Barber et al (1996) in the Equatorial Paci"c Study (EqPac) and Smith et al (in press) in the Antarctic Environment and Southern Ocean Process Study (AESOPS).…”

“…The Intermonsoon periods in the Arabian Sea are customarily referred to as oligotrophic periods, but their productivity values of 86$5 mmol C m\ d\ (Spring) and 80$12 mmol C m\ d\ (Fall) (Fig. 9) are two to three times the o!-equator productivity in the tropical Paci"c Ocean (29 $ 2 mmol C m\ d\ ) (Barber et al, 1996) or the multi-annual mean at the central North Paci"c HOT site (39 mmol C m\ d\ ) (Karl et al, 1995) (Table 4).…”

“…The Plexiglas2+ racks were unclamped as the array line was retrieved through the main stern A-frame. A complete description of the in situ procedure is given in Barber et al (1996).…”