Alaska compendium of ocean profile data [ACOD]: Archival CTD and nutrient hydrography from NOAA's EcoFOCI, EMA, and predecessor programs

This oceanographic data product represents a multi-decade collection of shipboard hydrography in Alaska waters, sampled by select programs of the US National Oceanic and Atmospheric Administration (NOAA).  Data types include basic physical (temperature and salinity) and chemical (dissolved nutrient) properties collected as profiles from oceanographic research vessels.  The geographic extent includes coastal and offshore areas of the Gulf of Alaska, Bering Sea, and the Chukchi Sea.  Temporal coverage is 1974-2021 (temperature and salinity) or 2001-2021 (nutrient data).  Data in this product were collected under programs associated with the NOAA Pacific Marine Environmental Laboratory (PMEL) and Alaska Fisheries Science Center (AFSC).  Three major data collection efforts are represented: (1) the Ecosystems and Fisheries-Oceanography Coordinated Investigations (EcoFOCI) program (PMEL and AFSC); (2) the Ecosystem Monitoring and Assessment program led by AFSC and sup..., Sampling methods and instrumentation have varied across years and sources.  Temperature and salinity profiles (1974-2021) were collected using profiling Conductivity and Temperature with Depth (CTD) instruments.  Early CTD data quality in highly stratified waters was often compromised due to rapid profiling through a sharp thermocline; salinity data prior to April 1987 are of lower quality in some cruises and should be used with care.  Since approximately 1988, the sampling instrument of choice has been the SeaBird Electronics (SBE) 911plus system.  On some earlier EMA cruises (prior to 2018), an SBE25 was used.  Sampling during the EcoFOCI program involved standardized descent rates that increase with depth, filtering and binning to standard 1 dbar resolution, additional post-processing to ensure data integrity, and consistent rules for surface interpolation.  Salinity was reported in units of parts per thousand prior to August 1995 and PSS-78 thereafter.&..., **Dataset Overview**

This product represents a single-point-of-access, quality-controlled collection of basic shipboard hydrographic data (temperature, salinity, and nutrients). These were sampled by select programs of the US National Oceanic and Atmospheric Administration (NOAA) in Alaska waters, including the Gulf of Alaska (GOA), Bering Sea (BS), and Chukchi Sea (CS). Data coverage is 1974-2021 (CTD) or 2001-2021 (nutrient). Data sources and methodology are fully described in Mordy et al. (2025, \"A compendium of temperature and salinity profiles and discrete nutrients from selected NOAA programs in Alaska\", *Scientific Data*) and are briefly summarized here.

NOAA's Pacific Marine Environmental Laboratory (PMEL) was established in 1973, and thereafter began environmental studies in Alaska waters that focused on the physical dynamics of the GOA, eastern BS, and CS. In 1984 a new program was established between PMEL and NOAA's Alaska Fisheries Science Center (AFSC) now known as Ecosys...,