Secchi disk depth (ZSD) measurements in the California Current 1949-2021

The Secchi disk depth (ZSD) measurements made in the California Current 1949-2021 were compiled from multiple sources but mostly from the California Cooperative Oceanic Fisheries Investigations (CalCOFI) cruises. An earlier version of this dataset was described in Aksnes, D.L., and M.D. Ohman. 2009. Multi-decadal shoaling of the euphotic zone in the southern sector of the California Current System. Limnol. Oceanog. 54, 1272–1281. This updated dataset was used in Kahru, M., Z. Lee, and M.D. Ohman. 2023. Multidecadal changes in ocean transparency: decrease in a coastal upwelling region and increase offshore. Limnol. Oceanogr., in press.