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Ocean color, chlorophyll, and harmful algal blooms

Find satellite-derived chlorophyll, ocean color, and harmful-algal-bloom (HAB) forecast products for a coastal region.

What this teaches

  • Discovering CoastWatch's HAB and ocean-color product family
  • Combining gridded satellite ocean color with in-situ measurements
  • Reading product variable lists for derived fields (chla_filled, reflectances, etc.)

Sources used: COASTWATCH, COASTWATCH_WC, NEFSC

Prompt

Find satellite ocean-color and chlorophyll products for the U.S. West
Coast. I want products that include harmful algal bloom indicators if
available.

Transcript

1. Free-text + scoped collections

search_datasets(
  q = "chlorophyll",
  collections = "COASTWATCH,COASTWATCH_WC,NEFSC",
  limit = 5
)

Real top hit:

ID Title
wvcharmV3_3day_LonPM180 C-HARM v3.1 3-Day Forecast — Pseudo-nitzschia, cellular & particulate domoic acid, gap-filled chlorophyll-a, 486 nm and 551 nm reflectances, salinity, water temperature — California & Southern Oregon coast, 2022-present
wvcharmV3_3day (same product, alternate longitude convention)
wvcharmV3_2day_LonPM180 C-HARM 2-day forecast variant

Provider: NOAA NMFS SWFSC ERD / CoastWatch West Coast. ERDDAP host: https://coastwatch.pfeg.noaa.gov/erddap. Coverage bbox: -127.5, 31.3, -117.0, 43.0 (CA + S. Oregon).

The C-HARM product blends near-real-time S-NPP VIIRS gap-filled chlorophyll, 486/551 nm reflectance, and SST/salinity/currents from the WCOFS ROMS model to produce probability-of-Pseudo-nitzschia and probability-of-domoic-acid grids.

2. Get the ERDDAP form

get_item(collection = "COASTWATCH_WC", item_id = "wvcharmV3_3day_LonPM180")

Returns ERDDAP griddap URL with all access formats (asc, csv, csvp, dods, nc, geotif, kml, json, …).

Result the agent gave

"544 chlorophyll-tagged items across the three queried collections. Top of the list is the C-HARM v3.1 product family from CoastWatch West Coast (NOAA NMFS SWFSC ERD):

  • wvcharmV3_3day_LonPM180 and wvcharmV3_3day — 3-day forecast variants
  • wvcharmV3_2day_LonPM180 — 2-day forecast variant

C-HARM is California / Southern Oregon's operational HAB forecast. It outputs probability of Pseudo-nitzschia exceeding 10,000 cells/L, probability of particulate domoic acid > 500 ng/L, and probability of cellular domoic acid > 10 pg/cell. Inputs blended into the model include S-NPP VIIRS gap-filled chlorophyll-a, 486 nm and 551 nm reflectance, surface salinity / SST / currents from the WCOFS ROMS regional model. Coverage bbox: -127.5°W to -117.0°W, 31.3°N to 43.0°N. ERDDAP griddap form: https://coastwatch.pfeg.noaa.gov/erddap/griddap/wvcharmV3_3day_LonPM180.html — supports NetCDF, GeoTIFF, KML, CSV, OPeNDAP.

For non-HAB chlorophyll across other coastal regions, narrow the search by changing q (e.g., q='VIIRS chlorophyll') and bbox for your region."

Variations

  • East Coast: replace West-Coast collections with NEFSC and COASTWATCH for similar HAB+chlorophyll products in the Northeast.
  • Just chlorophyll, no HAB: q = "chlorophyll" with exclude_collections = "INCIDENT_NEWS" and filter to q keyword MODIS or VIIRS.
  • Validation with in-situ: also include BCODM (BCO-DMO) for cruise-based chlorophyll measurements.