Quantifying Atmospheric Trace Element Deposition Over the Ocean on a Global Scale With Satellite Rainfall Products

Abstract

AbstractAtmospheric input of trace element micronutrients to the oceans is difficult to determine, as even with collection of high‐quality aerosol chemical concentrations, such data by themselves cannot yield deposition rates. To transform these concentrations into rates, a method of determining flux by applying an appropriate deposition velocity is required. A recently developed method based on the natural radionuclide 7Be has provided a means to estimate the bulk (wet + dry) deposition velocity (Vb) required for this calculation. Here, water column 7Be inventories and aerosol 7Be concentrations collected during the 2018 US GEOTRACES Pacific Meridional Transect are presented. We use these data together with those from other ocean basins to derive a global relationship between rain rate (m/yr) and bulk deposition velocity (m/day), such that Vb = 999 ± 96 × Rain rate + 1,040 ± 136 (R2 = 0.81). Thus, with satellite‐derived rainfall estimates, a means to calculate aerosol bulk deposition velocities is provided.