CoAuthors

Gregory Johnson (NOAA/PMEL, United States)

Changes in regional mean sea level can dramatically increase the flooding risk for island and low-lying coastal communities, and can have far larger magnitudes than the trend in global mean sea level. One important tool for understanding sea level variability and ensuring that we are measuring it accurately is the sea level budget (SLB). In this work, we investigate the “closure” of the SLB in the Southwest Pacific Basin by exploring whether the altimeter-based sea level anomaly measurements (from the NOAA/EUMETSAT Radar Altimeter Database System) match the sum of the anomalies in the independently observed steric (from Core and Deep Argo floats) and barystatic (from GRACE/GRACE-FO) sea level components. The Southwest Pacific Basin contains an operational multiyear Deep Argo array (beginning in January 2016) that has not yet been analyzed in this SLB framework. Previous work found it challenging to close the SLB in this region without the higher temporal and spatial coverage of the deep steric term that the Deep Argo floats provide. The Deep Argo float dataset is the most limited of the datasets used here in terms of spatial coverage and resolution (~5° × 5°) so the availability of these data limits where we can calculate the SLB and over what scale. We analyze the SLB within 6° × 6° grid cells that are equivalent in size to four GRACE/GRACE-FO mascons. By comparing the trend in the sea level anomaly to the trends in the barystatic and steric sea level terms, we quantify the impact of the Deep Argo data on the closure of the SLB over each 6° × 6° region for the Southwest Pacific Basin.