LOW-FREQUENCY VARIABILITY OF THE EQUATORIAL PACIFIC-OCEAN USING A NEWPSEUDOSTRESS DATASET - 1930-1989

Interannual and interdecadal variability of the equatorial Pacific are examined using a new pseudostress dataset. The monthly mean pseudostr ess fields (1930-89) are derived from Comprehensive Ocean-Atmosphere D ata Set (COADS) pseudostress using climate basis functions obtained fr om the Florida State University pseudostress product (1966-90). To val idate the new wind fields, a two-tier validation scheme was used. The new wind fields were first examined to see if they exhibited character istics that have been shown to be important in terms of exciting El Ni no events. Next, the new wind fields are used to force an ocean model, thereby obtaining model estimates of tropical Pacific currents and mo del upper-layer thickness (ULT). Observed sea level and spatially aver aged SST anomalies are used to validate the hindcasts. The new wind fi elds were found to have a significant El Nino mode (accounting for 41% of the variance), which possessed features consistent with those that theory and numerical simulations dictate. Interannual fluctuations in modeled and observed sea level fluctuations are compared at Galapagos and Truk, yielding correlation r values of 0.73 and 0.71, respectivel y. The comparison of the interannual fluctuations in modeled ULT and o bserved SST anomalies, which are both spatially averaged over a subdom ain in the eastern Pacific basin, results in an r value of 0.64. Inter decadal fluctuations in eastern Pacific model ULT are found to be qual itatively consistent with those in the spatially averaged observed SST anomalies. Stronger El Nino events are observed to occur during perio ds of higher Pacific ULT (for decadal and longer timescales). Comparis on of interdecadal fluctuations in global mean land air temperature an d eastern Pacific ULT suggests a connection between eastern Pacific SS T and tropical mean land air-temperature warming for interdecadal time scales.