Community Satellite Processing Package

NOAA Clouds from AVHRR Extended (CLAVR-x) Retrieval Software Package in Support of VIIRS, MODIS and AHVRR Version 2.0

7 April 2016

New release of the US National Oceanic and Atmospheric Administration (NOAA) software for transforming direct broadcast Suomi-NPP VIIRS Sensor Data Records (SDRs), NOAA-18, NOAA-19, MetOP-A and MetOP-B AVHRR, and Aqua and Terra MODIS Level-1B (L1B) files into Level 2 cloud products. CLAVR-x is NOAA's operational cloud processing system for the AVHRR, and in 2015 was updated to run the NOAA Enterprise Algorithms. The CLAVRx group is led by NOAA NESDIS Center for Satellite Applications and Research (STAR) scientist, Dr. Andrew Heidinger.

CLAVRx software produces single Field-of-View (FOV) cloud retrievals in HDF4 format from input AVHRR, MODIS, and VIIRS Imager calibrated/geolocated data files.

What is New in CSPP CLAVRx Version 2.0?

  • Addition of S-NPP VIIRS nighttime Day/Night Band (DNB) lunar reflectance model; this allows for the implementation of the VIIRS Nighttime Lunar Cloud Optical and Microphysical Properties (NLCOMP) retrievals.
  • VIIRS products now use I-Band and Day/Night Band data as input.
  • New output file naming convention (all output files are prefixed with “clavrx_”).
  • Added a number of new output product arrays, including an experimental Rain Rate product.
  • Re-structured radiative transfer module, the Pressure–layer Fast Algorithm for Atmospheric Transmittances (PFAAST).
  • More stable software execution as a result of bug fixes.
  • Some subroutines have been re-written for efficiency improvements.
  • Update to the Cloud Phase algorithm.
  • Revamped structure and logic for staging and downloading ancillary data.
  • Improvement in the quality and number of quicklooks.
  • Software compiled using gcc 4.9.2, built for CentOS 6 and later.

A few key CLAVRx output parameters are listed below:

  • cloud mask,
  • cloud type (13 categories),
  • cloud height,
  • cloud top pressure,
  • cloud top temperature,
  • cloud emissivity,
  • cloud optical depth,
  • cloud effective radius,
  • cloud phase,
  • rain rate (experimental),
  • VIIRS lunar reflectances,
  • VIIRS nighttime cloud optical depth,
  • VIIRS nighttime cloud effective radius,
  • product quality flags.
Other parameters, including ocean, land and aerosol products are also retrieved. Please see the documentation provided in the package for a complete list of products and a description of the retrieval algorithms. CLAVR-x source code is included with this release.

CLAVRx Version 2.0 System Requirements
  • Intel or AMD CPU with 64-bit instruction support,
  • 2 GB RAM
  • CentOS 6 64-bit Linux (or other compatible 64-bit Linux distribution),
  • 50 GB of disk space,
  • Internet connection (for downloading ancillary data).