เปรียบเทียบวิธี

	ดัชนีปริมาณน้ำฝนมาตรฐาน	แบบจำลองการไหลเวียนทั่วไป
สาขาวิชา	ธรณีฟิสิกส์	ธรณีฟิสิกส์
ตระกูล	Process / pipeline	Process / pipeline
ปีกำเนิด	1993	1975
ผู้ริเริ่ม	Thomas McKee, Neil Doesken, and John Kleist	Syukuro Manabe and Richard Wetherald
ประเภท	Probabilistic drought indicator	Deterministic coupled atmosphere-ocean simulation
แหล่งต้นตำรับ	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.	Manabe, S., & Wetherald, R. T. (1975). The effects of doubling the CO2 concentration on the climate of a general circulation model. Journal of the Atmospheric Sciences, 32(1), 3-15.
ชื่อเรียกอื่น	SPI	GCM, Global Climate Model
ที่เกี่ยวข้อง	3	3
สรุป	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.	A General Circulation Model (GCM), also called a Global Climate Model, is a three-dimensional numerical representation of the Earth's atmosphere, oceans, ice, and land surface that simulates physical processes governing weather and climate. Pioneered by Manabe and Wetherald in 1975, GCMs are the primary tools for understanding past climate, projecting future climate change, and investigating climate sensitivity to greenhouse gases and other forcings.