NEXRAD Level II observations restructured into an analysis-ready, cloud-optimized dataset. One time-aware
hierarchy instead of millions of files — open it lazily, slice by time, stream only what you touch.
Coverage
KLOT — Chicago / Romeoville, IL
Temporal
2015-01-01 → present
Volume
~166 TB cataloged
Variables
DBZH · ZDR · RHOHV · PHIDP · VRADH …
Coverage grows station by station — we list what is live, never projected coverage.
Source NEXRAD Level II observations are NOAA data disseminated through
NOAA Open Data Dissemination (NODD)
— open to the public to use, share, and analyze, with attribution requested for unaltered NOAA data. This
archive is a transformed, reorganized derivative produced by AtmoScale; it is not original, unaltered NOAA
data, and its use does not imply NOAA endorsement or affiliation.
Suggested attribution:
NOAA NEXRAD Level II observations, accessed through NOAA Open Data Dissemination and transformed into the
Radar DataTree analysis-ready format by AtmoScale.
Query it directly
# anonymous S3 reads — no credentials, no downloadsimport icechunk
import xarray as xr
storage = icechunk.s3_storage(bucket="nexrad-arco", prefix="KLOT", region="us-east-1", anonymous=True)
session = icechunk.Repository.open(storage).readonly_session("main")
dt = xr.open_datatree(session.store, engine="rustytree")
storm = dt["VCP-212/sweep_0"].sel(vcp_time="2026-03-10")
NEXRAD Level II observations converted into a cloud-optimized, analysis-ready format using Zarr v3 and Icechunk
— queryable directly with xarray, with no need to download or decode raw Level II files yourself.
The source NEXRAD Level II observations are NOAA data distributed through NOAA Open Data Dissemination — open to
the public to use, share, and analyze, with attribution requested. NEXRAD ARCO itself is a transformed,
reorganized derivative produced by AtmoScale; it is not original, unaltered NOAA data, and its use does not
imply NOAA endorsement or affiliation.
From 2015-01-01 to present for the KLOT radar (Chicago/Romeoville, IL) — roughly 166 TB cataloged so far.
Coverage grows station by station; only what is actually live is listed, never projected coverage.
Anonymous S3 reads — no credentials, no downloads. Open the store with icechunk, load it as an xarray datatree,
and slice by time or variable directly from the cloud.
The full set of dual-polarization moments: reflectivity (DBZH), differential reflectivity (ZDR), correlation
coefficient (RHOHV), differential phase (PHIDP), and radial velocity (VRADH).
No — it is the same underlying observations, but restructured. NEXRAD ARCO reorganizes the raw NEXRAD Level II
files (millions of small per-scan files) into one time-aware, cloud-optimized hierarchy, so you can open it
lazily and stream only the slice you need instead of downloading and decoding files yourself.