HR: 14:50h
AN: OS12B-05 INVITED     [PDF]
TI: Freshwater Flux Variations and Impacts on\\the North Pacific Ocean
AU: * Lukas, R
EM: rlukas@hawaii.edu
AF: Dept. of Oceanography, SOEST, University of Hawaii, 1000 Pope Road, Honolulu, HI 96822 United States
AB: Salinity profiles measured 100 km north of Oahu during the past 15 years as part of the Hawaii Ocean Time-series (HOT) reveal important changes in the upper ocean and thermocline. A prolonged freshening started first on shallower isopycnals within the thermocline during the mid-1990s, occurring progressively later on deeper isopycnals. The freshening trend was reversed in the upper pycnocline during 1998 in concert with a pronounced increase in mixed layer salinity. The increased upper ocean salinity was attributed to the regional drought associated with the 1997-98 El Ni\~{n}o event, however the trend continued after that event ended and through 2001 resulting in a salinity change of approximately 1 psu. The ECCO data assimilation results show corresponding large-scale high salinity anomalies in the North Pacific for the period 1998-2001. The impacts of the salinity variations at ALOHA include a pronounced reduction of the stratification of the upper ocean during this period (with deeper wintertime mixing), as well as a significant reduction in the oceanic CO$_{2}$ sink. A pattern of drought associated with the Pacific Decadal Oscillation appears to be responsible for the persistence of the HOT salinity anomaly. The pycnocline freshening has been attributed to the subduction and subsequent southward advection of earlier wintertime precipitation anomalies in the storm track region north of Hawaii. The apparent time scale of these variations is about a decade. The 1998-2001 North Pacific surface salinity anomaly pattern roughly corresponds to the precipitation and net freshwater flux anomalies for the same period from the CMAP rainfall and the NCEP/NCAR reanalysis evaporation.
DE: 1620 Climate dynamics (3309)
DE: 1655 Water cycles (1836)
DE: 3339 Ocean/atmosphere interactions (0312, 4504)
DE: 3354 Precipitation (1854)
DE: 4504 Air/sea interactions (0312)
SC: Ocean Sciences [OS]
MN: 2003 Fall Meeting