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Added Precipitation Concentration Index(PCI), issue #459

@oshin94 This is an unexpected addition to this package's suite of indices. You just came out of nowhere and made it happen, lickety-split. I totally appreciate your contribution!

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Nov 30, 2021

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Climate Indices in Python

This project contains Python implementations of various climate index algorithms which provide a geographical and temporal picture of the severity of precipitation and temperature anomalies useful for climate monitoring and research.

The following indices are provided:

  • SPI, Standardized Precipitation Index, utilizing both gamma and Pearson Type III distributions
  • SPEI, Standardized Precipitation Evapotranspiration Index, utilizing both gamma and Pearson Type III distributions
  • PET, Potential Evapotranspiration, utilizing either Thornthwaite or Hargreaves equations
  • PDSI, Palmer Drought Severity Index
  • scPDSI, Self-calibrated Palmer Drought Severity Index
  • PHDI, Palmer Hydrological Drought Index
  • Z-Index, Palmer moisture anomaly index (Z-index)
  • PMDI, Palmer Modified Drought Index
  • PNP, Percentage of Normal Precipitation

This Python implementation of the above climate index algorithms is being developed with the following goals in mind:

  • to provide an open source software package to compute a suite of climate indices commonly used for climate monitoring, with well documented code that is faithful to the relevant literature and which produces scientifically verifiable results
  • to provide a central, open location for participation and collaboration for researchers, developers, and users of climate indices
  • to facilitate standardization and consensus on best-of-breed climate index algorithms and corresponding compliant implementations in Python
  • to provide transparency into the operational code used for climate monitoring activities at NCEI/NOAA, and consequent reproducibility of published datasets computed from this package
  • to incorporate modern software engineering principles and programming best practices

This is a developmental/forked version of code that is originally developed and maintained by NIDIS/NCEI/NOAA. The official release version is available at


You can cite climate_indices in your projects and research papers via the BibTeX entry below.

@misc {climate_indices,
    author = "James Adams",
    title  = "climate_indices, an open source Python library providing reference implementations of commonly used climate indices",
    url    = "",
    month  = "may",
    year   = "2017--"


Climate indices for drought monitoring, community reference implementations in Python



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