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Mean SST, D20, and Vertical pumping velocity SPURS-2: High T, low S, shallow themrocline, and high vertical pumping. Questions: How the low salinity is maintained? How the low salinity varies, and what processes are responsible?
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Mean SST, D20, and Vertical pumping velocity SPURS-2: High T, low S, shallow themrocline, and high vertical pumping • Questions: • How the low salinity is maintained? • How the low salinity varies, and what processes are responsible? • What’s the role of resurfacing or obduction of the thermocline water with a subtropical origin?
Tracking the obduction of 13°C Water using a passive tracer The passive tracer was originally released in the density range of 0.1 σθabove and below its vertical gradient minimum in 8°S-8°N and 130W°-90°W and integrated forward for 80 years. Qu, Gao, Fukumori, Fine, and Lindstrom, JPO, 2010
The 13°C Water is a thick themostad, halostad water mass lying at temperatures near 13ºC and salinities near 34.9 psu (26.2< σθ<26.6) within about 5º of the equator and east of about 150ºW. Tsuchiya (1981) Near 13°C, 26.44 σθ halostad thermostad Thermosteric anomaly in cl l-1 (left panel) and salinity in psu (right panel) from STD data taken along 105°W, 21 February-3 March 1967 (After Tsuchiya, 1981). The 13ºC isotherm is almost identical with 160 cl l-1 (corresponding to 26.44 σθ) density surface.
The 13C Water enters the mixed layer in the eastern tropical Pacific, along the American coast, as well as in the SPURS-2 region.
Less 13C water was obducted in the eastern equatorial Pacific and along the American coast during the 997/98 El Nino. More 13C water was obducted in the SPURS-2 region during the 1997/98 El Nino *