قارن الطرق

	نموذج الدوران العام	مؤشر التوحيد القياسي للهطول
المجال	الجيوفيزياء	الجيوفيزياء
العائلة	Process / pipeline	Process / pipeline
سنة النشأة	1975	1993
صاحب الطريقة	Syukuro Manabe and Richard Wetherald	Thomas McKee, Neil Doesken, and John Kleist
النوع	Deterministic coupled atmosphere-ocean simulation	Probabilistic drought indicator
المصدر التأسيسي	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.	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.
الأسماء البديلة	GCM, Global Climate Model	SPI
ذات صلة	3	3
الملخص	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.	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.