Repeated and random components in Oklahoma's monthly precipitation record

Authors: Garbrecht, Jurgen; Brown, David; Zhang, Xunchang

Submitted to: International Soil and Water Conservation Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/19/2018
Publication Date: 3/24/2018
Citation: Garbrecht, J.D., Brown, D.P., Zhang, X.J. 2018. Repeated and random components in Oklahoma's monthly precipitation record. International Soil and Water Conservation Research. 6: p. 261-263. https://doi.org/10.1016/j.iswcr.2018.03.005.
DOI: https://doi.org/10.1016/j.iswcr.2018.03.005

Interpretive Summary: Precipitation across Oklahoma exhibits a high degree of spatial and temporal variability and creates numerous water resources management challenges. The monthly precipitation record of central Oklahoma was evaluated in a proof-of-concept to establish whether a simple monthly precipitation decomposition into repeatable (expected) and unexpected (random) components could identify the odds of encountering repeatable or unexpected monthly precipitation in the future. Risk-based decision making in agricultural and water resources management may find value in knowing the extent to which historical precipitation can provide guidance for inferring expectations of future monthly precipitation. A 123-year long monthly precipitation record of central Oklahoma was evaluated to determine the odds of future precipitation to be repeatable or random. The odds of identifying monthly precipitation as repeat-seasonal or unexpected-random can be considered a climatic characteristic that complements other available statistical parameters to describe and understand sources of precipitation variations. An improved understanding of the historical magnitude and frequency of this unexpected component of precipitation variability can enhance producer confidence when incorporating climatic considerations into management decisions.

Technical Abstract: Precipitation across Oklahoma exhibits a high degree of spatial and temporal variability and creates numerous water resources management challenges. The monthly precipitation record of the Central Oklahoma climate division was evaluated in a proof-of-concept to establish whether a simple monthly precipitation decomposition into repeatable (expected) and unexpected (random) components could identify the odds of encountering repeatable or unexpected monthly precipitation in the future. Risk-based decision making in agricultural and water resources management may find value in knowing the extent to which historical precipitation can provide guidance for inferring expectations of future monthly precipitation. A 123-year long monthly precipitation record of central Oklahoma was used to determine the odds of future precipitation to be repeatable or random. The metric for identifying precipitation kind was based on it being inside or outside a range defined by the relative difference between random and a percentage of repeatable precipitation. For climate conditions in central Oklahoma, the odds of future precipitation being repeatable were between 18 and 33% depending on the month of the year. The corresponding odds of being of random were 67 to 82 %. Thus, relying solely on historical precipitation records to anticipate future monthly precipitation has a low probability of success in central Oklahoma.