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Technical Documentation, State of the Ecosystem Report

58 Thermal Habitat Gridded

Description: The number of days per year per 1/12 degree cell that exceeds a temperature threshold.

Found in: State of the Ecosystem - Mid-Atlantic (2024), State of the Ecosystem - New England (2024), State of the Ecosystem - Indicator Catalog (2024+)

Indicator category: Extensive analysis, not yet published

Contributor(s): Joseph Caracappa

Data steward: Joseph Caracappa

Point of contact: Joseph Caracappa

Public availability statement: Source data are publicly available.

58.1 Methods

58.1.1 Data sources

Daily bottom temperature data were obtained from GLORYS global reanalysis using Copernicus Marine Service’s API toolbox. GLOYRS is a data assimilative model that incorporates a wide range of global observational data including NOAA observations in the World Ocean Database. This product starts in 1993 to present day and is updated quarterly with a spatial resolution of 1/12 degree.

58.1.2 Data analysis

Daily files are first cropped to the EPU footprint shapefile, so that only the Northeast Shelf LME is used in the analysis. Then all values below a given temperature threshold are masked out. The daily values are constructed as an annual file with a daily time dimension.

58.1.2.1 thermal_habitat_gridded

For ecodata::thermal_habitat_gridded, the number of days exceeding a temperature threshold is calculated for each grid cell. This produces an annual file for each temperature threshold for the entire Northeast US Shelf showing the number of days exceeding a temperature threshold. These annual files are flattened into a table for ecodata and maps each coordinate to an EPU and depth band (0 - 25m, 25 - 100m, 100 - 300m, and All Depths). Coordinates with zero days exceeding a threshold are dropped.

First, a binary mask is applied to each annual gridded file (with daily timesteps) to convert all cells that exceed a temperature threshold as 1 and 0 otherwise. Then, the total area of those exceeding cells is calculated for each day in that year. Finally, the average daily area is calculated as the main indicator value.

58.1.3 Data processing

Thermal habitat indices are constructed using a workflow in the bottom_temp_SOE repository, which utilizes gridded data functions found in the EDABUtilities package.

This work was built off of similar analysis conducted as part of the 2025 Atlantic Sea Scallop Research Track Stock Assessment.

catalog link https://noaa-edab.github.io/catalog/thermal_habitat_gridded.html