ISCCP-H¶

International Satellite Cloud Climatology Project (ISCCP) H-Series Climate Data Record

Discontinued

At a glance¶

Note on period: The official CDR covers 1983-07-01 to 2017-06-30 (NCEI metadata; the last Basic HGM file on AWS is June 2017). An interim ICDR made the same way fills July 2017 to December 2018, and NCEI says it will stay available only until the final CDR for that period is released.

Overview¶

ISCCP-H is a global cloud climate data record from 1983 onward, built by combining visible and infrared imagery from the world's geostationary weather satellites with NOAA and MetOp polar orbiters (AVHRR). Every three hours it provides cloud amount, cloud-top pressure and temperature, optical thickness, water path and cloud type on a 1° grid, making it nearly the only long record that resolves the diurnal cycle of clouds. It is the third generation, replacing ISCCP-D, and comes as a Full version for specialists and a simpler CF-compliant Basic version.

What changes with the successor¶

ISCCP-D → ISCCP-H¶

Transition: 2017-06

The third ISCCP generation, rebuilding ISCCP-D (produced at NASA GISS through 2009) with new pixel sampling, grids and calibration. It is a generation change within this page, so it is described here.

Sources: Young et al. (2018), ESSD — ISCCP H-Series CDR product · NCEI — International Satellite Cloud Climatology Project

Available variables¶

Names and units are from the ISCCP-Basic HGM files (NCEI THREDDS aggregation). In the Full version the same names hold 8-bit counts, and in Full HGG cloud amount is stored as pixel counts (n_cloudy/n_total).

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

Monthly mean cloud properties (Basic HGM)¶

3-hourly grid (Basic HGG)¶

The full variable list is in the official documentation.

How to get the data¶

• NCEI direct download (Full and Basic) — HTTPS directory
  • Full HGM and HGH and Basic HGG, HGH and HGM are downloadable. Full HGG, HXG and HXS are large and are ordered through ncei.sat.info@noaa.gov.
• NCEI THREDDS (ISCCP-H Basic aggregations) — THREDDS / OPeNDAP / NCSS
  • Basic HGG, HGH and HGM are aggregated into single time series (Best Time Series) that can be subset remotely.
• AWS open bucket (noaa-cdr-cloud-properties-isccp-pds) — S3 (anonymous access)
  • Files are under data/isccp/ (Full) and data/isccp-basic/hgg|hgh|hgm/ (Basic).
• Google Cloud open bucket (noaa-cdr-cloud-properties-isccp) — GCS
• Interim ICDR (2017-07 to 2018-12, FTP) — FTP (isccp/ = Full, isccp_basic/ = Basic)
  • Temporary data, not the official CDR. Chrome and Firefox no longer support FTP, so use an FTP client or command-line tool.

Example code¶

Reads one month of Basic HGM from the AWS open bucket without an account. The file name follows the pattern seen in the bucket listing.

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

fs = s3fs.S3FileSystem(anon=True)
key = ("noaa-cdr-cloud-properties-isccp-pds/data/isccp-basic/hgm/"
       "ISCCP-Basic.HGM.v01r00.GLOBAL.2016.01.99.9999.GPC.10KM.CS00.EA1.00.nc")
ds = xr.open_dataset(fs.open(key), engine="h5netcdf")

ca = ds["cldamt"].squeeze()                 # monthly mean cloud amount (percent), 1° lat-lon grid
w = np.cos(np.deg2rad(ds["lat"]))
print(float(ca.weighted(w).mean(("lat", "lon"))))   # area-weighted global mean

Practical tips¶

• July 2017 onward is not the official CDR. If you extend through 2017–2018, state in your paper that you used the interim ICDR, and use other records after that.
• NCEI's caveats note a two-year gap in polar-orbiter (NOM) data during the NOAA-15 to NOAA-17 transition (2000–2002), and missing visible channels in many MET-3 images in 1995 and GMS-3 images in February–April 1986. Be careful with trends and diurnal analyses in these periods.
• Cloud amount changes by about 0.05 between nadir and slant views. Regional values can step up or down when a geostationary satellite is replaced or relocated.
• Low clouds under thin high cloud are hard to see. The users guide says high cloud is about 0.10 too low and middle cloud about 0.10 too high compared with lidar.
• In the Full version, values are counts. Averaging them without the lookup tables gives numbers with no physical meaning. If you are new to ISCCP, start with the Basic version.
• The Basic version remaps the equal-area grid onto 1° latitude-longitude cells, so at high latitudes several cells share the same original value. Always apply area weighting (cosine of latitude).

Notices and change history¶

References for your paper¶

Dataset citation¶

ISCCP H-Series CDR — DOI 10.7289/V5QZ281S

@misc{isccp_h_cdr,
  author    = {Rossow, William B. and Walker, Alison and Golea, Violeta and Knapp, Kenneth R. and Young, Alisa and Inamdar, Anand and Hankins, Bill},
  title     = {International Satellite Cloud Climatology Project Climate Data Record, H-Series},
  year      = {2016},
  publisher = {NOAA National Centers for Environmental Information},
  doi       = {10.7289/V5QZ281S}
}

Reference papers¶

ISCCP-H product description paper — DOI 10.5194/essd-10-583-2018

@article{young2018isccph,
  author  = {Young, Alisa H. and Knapp, Kenneth R. and Inamdar, Anand and Hankins, William and Rossow, William B.},
  title   = {The International Satellite Cloud Climatology Project {H}-Series climate data record product},
  journal = {Earth System Science Data},
  volume  = {10},
  pages   = {583--593},
  year    = {2018},
  doi     = {10.5194/essd-10-583-2018}
}

Advances in understanding clouds from ISCCP (cited in the NCEI use agreement) — DOI 10.1175/1520-0477(1999)080<2261:AIUCFI>2.0.CO;2

@article{rossow1999isccp,
  author  = {Rossow, William B. and Schiffer, Robert A.},
  title   = {Advances in Understanding Clouds from {ISCCP}},
  journal = {Bulletin of the American Meteorological Society},
  volume  = {80},
  number  = {11},
  pages   = {2261--2287},
  year    = {1999},
  doi     = {10.1175/1520-0477(1999)080<2261:AIUCFI>2.0.CO;2}
}

Acknowledgements¶

The NOAA CDR use agreement asks users to state that the data were obtained from NCEI, to credit the CDR developers and their affiliations, and to note NOAA CDR Program support with "Development of the CDR was supported by NOAA's CDR Program." When a CDR is central to the work, it also encourages offering co-authorship to the developers.

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 — ISCCP H-Series overview (product table, ICDR, documents)
• NCEI — Cloud Properties ISCCP H-Series CDR (CDR document package)
• ISCCP Data Users Guide v5.0 (PDF)
• ISCCP-H caveats document
• ISCCP Basic versus Full description
• ISCCP user Q&A forum (Google Groups)