PATMOS-x¶

Pathfinder Atmospheres – Extended (PATMOS-x) Version 6.0 — NOAA Climate Data Record of AVHRR and HIRS Reflectance, Brightness Temperature, and Cloud Products

Available

At a glance¶

Note on period: NCEI metadata gives 1981-08-25 as the start (the CDR overview page says '1979–present'). When checked on 2026-10-13, the latest files in the AWS copy were NOAA-20 for 2026-07-04 and Metop-B and C for 2026-06-30. NOAA-15, 18 and 19 files end in late June 2025.

Overview¶

PATMOS-x is a global cloud climate data record from the early 1980s onward, combining AVHRR imagery and HIRS infrared spectral data from the NOAA and Metop polar orbiters. For each satellite it provides daily ascending and descending orbit files on a 0.1° grid with cloud fraction and type, cloud-top temperature, pressure and height, emissivity, optical depth and particle size, plus calibrated reflectances and brightness temperatures. Because each satellite's overpass time is preserved, users can deal with orbital drift and observation time directly.

What changes with the successor¶

PATMOS-x v5.3 (AVHRR only) → PATMOS-x v6.0 (AVHRR+HIRS)¶

Transition: 2021

Adds HIRS infrared spectral data to the AVHRR-only v5.3 to improve cloud-top height retrievals. A version change within this page.

Sources: Foster et al. (2023), J. Climate — PATMOS-x Version 6.0 · NCEI metadata — PATMOS-x v6.0 (C00926)

Available variables¶

In-file variable names were added to the NCEI CDR variable list. Names and units come from the Level-2b file specification example on the CIMSS PATMOS-x documentation page (header of a v05r03 file) and the table of fields new in v6.0 (Foster et al. 2023, J. Climate, Appendix Table C1). Confirm the names in a v6.0 file with ds.data_vars.

instantaneous mean accumulated maximum minimum static — instantaneous: value at the time stamp · mean/accumulated/maximum/minimum: over the indicated interval · static: does not change with time

Cloud properties (observations at overpass time)¶

Atmosphere and radiances¶

The full variable list is in the official documentation.

How to get the data¶

• NCEI direct download (2000 to present) — HTTPS directory (by year)
  • According to NCEI this path holds 2000 onward only. Get 1981–1999 from AWS or Google Cloud.
• AWS open bucket (noaa-cdr-patmosx-radiances-and-clouds-pds) — S3 (anonymous access)
  • The full period is under data/<year>/. Single files are large, about 400–500 MB.
• Google Cloud open bucket (noaa-cdr-patmosx-radiances-and-clouds) — GCS
• CIMSS PATMOS-x page (Climate Data Portal, subsetting) — Web
  • For a small area or a few variables, the CIMSS Climate Data Portal offers spatial and variable subsetting.

Example code¶

Opens one daily file from AWS without an account. Check variable names with ds.data_vars after opening.

# pip install s3fs xarray h5netcdf
import s3fs
import xarray as xr

fs = s3fs.S3FileSystem(anon=True)
# NOAA-19 ascending (afternoon) orbit, observed 2020-12-01. The c<creation> part varies, so use glob.
keys = fs.glob("noaa-cdr-patmosx-radiances-and-clouds-pds/data/2020/"
               "patmosx_v06r00_NOAA-19_asc_d20201201_*.nc")
ds = xr.open_dataset(fs.open(keys[0]), engine="h5netcdf")
print(ds.attrs.get("title"))
for name, v in ds.data_vars.items():
    print(name, v.attrs.get("long_name"), v.attrs.get("units"))

Practical tips¶

• One file is 'one satellite, one orbit direction, one day'. When you average several satellites into daily or monthly means, remember that different overpass times mix in the diurnal cycle. For trends it is safer to analyse each orbit family separately.
• NCEI says much of the NOAA-20 data has reflectances processed too high at oblique sun angles, biasing cloud optical properties high in some regions. Data for July 2018, January 2019 and after 13 January 2026 are not affected, and the fix is planned for Version 7.0.
• The NOAA-18 HIRS 13.3 µm channel produced corrupt data from January to 29 April 2023, so NOAA-18 cloud detection and height may be inconsistent in that period.
• Metop-C carries no HIRS, and HIRS failed in the later part of the Metop-B record. Cloud heights from these satellites are filled by other methods without HIRS.
• NOAA-15, 18 and 19 files end in late June 2025, leaving Metop-B, Metop-C and NOAA-20. Around 2025 the afternoon-orbit source effectively switches from AVHRR (NOAA-19) to VIIRS (NOAA-20), so take care when joining time series.
• The PATMOS-x file listing on NCEI THREDDS is the old v05r03 version. Get v6.0 from NCEI direct download, AWS or Google Cloud.

Notices and change history¶

References for your paper¶

Dataset citation¶

PATMOS-x Version 6.0 CDR — DOI 10.7289/V5X9287S

@misc{patmosx_v6_cdr,
  author    = {Foster, Michael J. and Phillips, Coda and Heidinger, Andrew K. and {NOAA CDR Program}},
  title     = {{NOAA} Climate Data Record ({CDR}) of Advanced Very High Resolution Radiometer ({AVHRR}) and High-resolution Infra-Red Sounder ({HIRS}) Reflectance, Brightness Temperature, and Cloud Products from Pathfinder Atmospheres - Extended ({PATMOS-x}), Version 6.0},
  year      = {2021},
  publisher = {NOAA National Centers for Environmental Information},
  doi       = {10.7289/V5X9287S}
}

Reference papers¶

PATMOS-x v6.0 description paper — DOI 10.1175/JCLI-D-22-0147.1

@article{foster2023patmosx,
  author  = {Foster, Michael J. and Phillips, Coda and Heidinger, Andrew K. and Borbas, Eva E. and Li, Yue and Menzel, W. Paul and Walther, Andi and Weisz, Elisabeth},
  title   = {{PATMOS-x} Version 6.0: 40 Years of Merged {AVHRR} and {HIRS} Global Cloud Data},
  journal = {Journal of Climate},
  volume  = {36},
  pages   = {1143--1160},
  year    = {2023},
  doi     = {10.1175/JCLI-D-22-0147.1}
}

Acknowledgements¶

The NOAA CDR use agreement asks users to state that the data were acquired from NOAA NCEI and to credit the developers (Andy Heidinger, Mike Foster) and the NOAA CDR Program. The use agreement also gives a citation in the form 'Heidinger, A.; Foster, M. and NOAA CDR Program (2020): NOAA Climate Data Record (CDR) PATMOS-x Cloud Properties, Version 6.0'.

Information on the datasets used in this study was compiled with the help of the Korean Climate Data Navigator (KCDN) (Sim, 2026; https://doi.org/10.5281/zenodo.23300923).

Links¶

• NCEI — PATMOS-x Cloud Properties CDR (notices and documents)
• NCEI metadata — PATMOS-x v6.0
• Algorithm documents (ACHA, DCOMP, Rev 2)
• CIMSS — PATMOS-x
• Foster et al. (2023), J. Climate