Comparison of measurements from pressure-recording inverted echo sounders and AVISO satellite altimetry in the North Equatorial Current region

초록

An array of 5 pressure-recording inverted echo sounders (PIESs) was deployed in conjunction with Jason-2 214 ground track across the North Equatorial Current (NEC) in the western North Pacific. PIES measures round-trip acoustic travel time from the sea floor to the sea surface and ocean bottom pressure, which are used to estimate sea level anomalies (SLA)caused by mass-loading and steric effects. AVISO along-track Mono-mission SLA (Mono-SLA)and daily reference mapped SLA (Ref-MSLA) products are used for comparison with PIES-derived SLA. Comparisons reveal that PIES-derived SLA shows a better agreement with Ref-MSLA than Mono-SLA. Mismatches larger than 10 cm with Mono-SLA are found. Correlation coefficients are relatively low ranging 0.65?0.79 with Mono-SLA but high ranging 0.78?0.87 with Ref-MSLA. Comparisons between ascending and descending-track Mono-SLAs at two crossover points closest the PIES array also show large differences even though their measuring time is different by only 1.5 and 4.6 days. Ref-MSLA takes nearly central value of the Mono-SLAs at the two crossover points. We will present what can cause the large mismatches between AVISO SLAs and PIES-derived SLA in our study area.