Consistency of the current global ocean observing systems from an Argo perspective

[摘要] Variations in the world's ocean heat storage and its associated volumechanges are a key factor to gauge global warming and to assess the earth'senergy and sea level budget. Estimating global ocean heat content (GOHC) andglobal steric sea level (GSSL) with temperature/salinity data from the Argonetwork reveals a positive change of 0.5 ± 0.1 W m⁻² (applied tothe surface area of the ocean) and 0.5 ± 0.1 mm year⁻¹ duringthe years 2005 to 2012, averaged between 60° S and 60° Nand the 10–1500 m depth layer. In this study, we present an intercomparisonof three global ocean observing systems: the Argo network, satellitegravimetry from GRACE and satellite altimetry. Their consistency isinvestigated from an Argo perspective at global and regional scales duringthe period 2005–2010. Although we can close the recent global ocean sealevel budget within uncertainties, sampling inconsistencies need to becorrected for an accurate global budget due to systematic biases in GOHC andGSSL in the Tropical Ocean. Our findings show that the area around theTropical Asian Archipelago (TAA) is important to closing the global sea levelbudget on interannual to decadal timescales, pointing out that the stericestimate from Argo is biased low, as the current mapping methods areinsufficient to recover the steric signal in the TAA region. Both the largeregional variability and the uncertainties in the current observing systemprevent us from extracting indirect information regarding deep-ocean changes.This emphasizes the importance of continuing sustained effort in measuringthe deep ocean from ship platforms and by beginning a much needed automateddeep-Argo network.

[学科分类] 海洋学与技术