手法を比較

	放射性炭素年代測定法	標準化降水量指数 (Standardized Precipitation Index)
分野	地球物理学	地球物理学
系統	Process / pipeline	Process / pipeline
提唱年	1949	1993
提唱者	Willard Libby	Thomas McKee, Neil Doesken, and John Kleist
種類	Chronometric method based on ¹⁴C decay	Probabilistic drought indicator
原典	Libby, W. F. (1949). Radiocarbon dating. University of Chicago Press.	McKee, T. B., Doesken, N. J., & Kleist, J. (1993). The relationship of drought frequency and duration to time scales. Proceedings of the Eighth Conference on Applied Climatology, 179-184.
別名	¹⁴C dating, Carbon-14 dating	SPI
関連	3	3
概要	Radiocarbon dating is a radiometric technique that determines the age of organic materials by measuring the radioactive decay of ¹⁴C (carbon-14), a rare isotope produced in the atmosphere by cosmic ray interactions. Developed by Willard Libby in 1949, radiocarbon dating became a foundational method in archaeology, paleoclimate studies, and geology, enabling dating of organic materials from the past ~50,000 years with typical precision of ±50–100 years.	The Standardized Precipitation Index (SPI) is a climate index that quantifies precipitation anomalies relative to historical norms, standardized to account for differences in precipitation climatology across regions. Introduced by McKee, Doesken, and Kleist in 1993, SPI has become a primary tool for drought detection and characterization, adopted by meteorological agencies worldwide for operational drought monitoring and early warning systems.