Tags: ocean color · chlorophyll-a · Bio-Argo · PACE · machine learning · NOAA
CHLA-Z is a global gridded dataset providing estimates of chlorophyll-a concentration as a function of depth (0–200 m) on a regular latitude/longitude grid, along with derived vertical-structure metrics.
The product is generated using a boosted regression tree (BRT) model trained on PACE OCI Level-3 mapped remote-sensing reflectances (Rrs) and in-situ chlorophyll profile observations from Bio-Argo and OOI.
gs://nmfs_odp_nwfsc/CB/fish-pace-datasets/chla-z
Public HTTPS access (no authentication required):
https://storage.googleapis.com/nmfs_odp_nwfsc/CB/fish-pace-datasets/chla-z/
Note: Google Cloud Console “Browse” links require login even for public buckets.
Use HTTPS links or example files for anonymous access.
- Repo: https://github.com/fish-pace/chla-z
- Example notebook | Open in Google Colab
- Dataset metadata (
chla-z.json) - Notebooks documenting dataset creation (see README in folder)
-
Core variable:
CHLA(time,z,lat,lon) — chlorophyll-a concentration (mg m⁻³) -
Derived layers:
CHLA_int_0_200(mg m⁻²)CHLA_peak(mg m⁻³)CHLA_peak_depth(m)CHLA_depth_center_of_mass(m)
-
Vertical grid: 10 m bin centers with bounds
z_start/z_end -
Spatial grid: global regular lat/lon (~4 km nominal; 0.041666668° step)
-
Temporal resolution: daily
-
Formats:
- Zarr v3 (cloud-optimized)
- NetCDF (one file per day)
Note on “4 km”:
This dataset is on a regular latitude/longitude grid (0.041666668°).
North–south spacing is approximately constant; east–west spacing decreases with latitude (cos(lat)).
import xarray as xr
zarr_url = "gcs://nmfs_odp_nwfsc/CB/fish-pace-datasets/chla-z/zarr"
ds = xr.open_zarr(
zarr_url,
consolidated=False,
storage_options={"token": "anon"}
)
# Example: time series at a point (nearest grid cell)
pt = ds["CHLA"].sel(lon=-155, lat=20, method="nearest")
pt = pt.isel(z=0) # surface
pt.sel(time=slice("2024-03-01", "2024-04-01")).plot()import xarray as xr
url = "gcs://nmfs_odp_nwfsc/CB/fish-pace-datasets/chla-z/netcdf/chla_z_20240305_v2.nc"
ds = xr.open_dataset(
url,
engine="h5netcdf",
storage_options={"token": "anon"}
)
# Plot surface CHLA for that day
ds["CHLA"].isel(time=0, z=0).plot()Note: R typically does not stream NetCDF directly from
gs://.
Download via HTTPS first.
library(terra)
url <- "https://storage.googleapis.com/nmfs_odp_nwfsc/CB/fish-pace-datasets/chla-z/netcdf/chla_z_20240305_v2.nc"
download.file(url, "chla_z_20240305_v2.nc", mode = "wb")
r <- rast("chla_z_20240305_v2.nc", subds = "CHLA") # 20 z layers
surf <- r[[1]] # surface CHLA
plot(log10(surf), main = "log10 Surface CHLA (z = 1)")If you use this dataset, please cite:
Holmes, E. (2026). CHLA-Z: Global chlorophyll-a vertical distribution (0–200 m) derived from PACE OCI and Bio-Argo using a BRT model (draft). NOAA Fisheries (NMFS). Public Zarr v3 Dataset available NOAA Open Data Dissemination (NOAA) Program. version 0.1.0 (2026-01-09). https://doi.org/10.5281/zenodo.18204004
Research / draft product.
Validation and uncertainty characterization are in progress.
Variable names, grid, and access paths are expected to remain stable; algorithm details may evolve.
Inputs include PACE OCI Level-3 mapped remote-sensing reflectances (NASA/GSFC/OBPG) and Bio-Argo profile observations.
Dataset and code are provided under CC-BY 4.0 unless otherwise noted.
This repository is a scientific product and is not official communication of the National Oceanic and Atmospheric Administration, or the United States Department of Commerce. All NOAA GitHub project code is provided on an ‘as is’ basis and the user assumes responsibility for its use. Any claims against the Department of Commerce or Department of Commerce bureaus stemming from the use of this GitHub project will be governed by all applicable Federal law. Any reference to specific commercial products, processes, or services by service mark, trademark, manufacturer, or otherwise, does not constitute or imply their endorsement, recommendation or favoring by the Department of Commerce. The Department of Commerce seal and logo, or the seal and logo of a DOC bureau, shall not be used in any manner to imply endorsement of any commercial product or activity by DOC or the United States Government.