An Assessment of Vertical Carbon Flux Parameterizations Using Backscatter Data From BGC Argo

Abstract

AbstractModel parameterizations of particulate organic carbon (POC) flux are critical for simulating the strength and future evolution of the biological carbon pump (BCP) but remain poorly constrained because direct observations are sparse. Here, we ask whether the Biogeochemical (BGC)‐Argo proxy observations of POC can help distinguish between these parameterizations by objectively comparing two common parameterizations, which reproduce the observed slowdown of flux attenuation with depth by either decreasing the remineralization rate or increasing the sinking velocity. Both can well reproduce the BGC‐Argo observations in top 1,000 m but predict different POC concentration below, making them possible to be distinguished if BGC‐Argo observations were available there. Therefore, an integration of backscatter sensors into the Deep Argo program is recommended to provide full depth proxy measurements. If the parameterization is known, POC flux can be determined from POC concentration. Thus, the BGC‐Argo proxy observations of POC concentration provide new insights into the BCP.