So sánh phương pháp

	Palmer Drought Severity Index	Fire Danger Rating System
Lĩnh vực	Disaster Studies	Disaster Studies
Họ	Process / pipeline	Process / pipeline
Năm ra đời	1965	1977
Người khởi xướng	Wayne C. Palmer (1965); self-calibrating variant by Wells, Goddard & Hayes (2004)	John E. Deeming, Robert E. Burgan & Jack D. Cohen (US NFDRS); C. E. Van Wagner (Canadian FWI System)
Loại	Water-balance soil-moisture drought index	Operational fuel-moisture and fire-behavior index pipeline
Công trình gốc	Palmer, W. C. (1965). Meteorological Drought. Research Paper No. 45, U.S. Department of Commerce, Weather Bureau, Washington, DC, 58 p.	Deeming, J. E., Burgan, R. E., & Cohen, J. D. (1977). The National Fire-Danger Rating System — 1978. General Technical Report INT-39, USDA Forest Service, Intermountain Forest and Range Experiment Station, Ogden, UT, 63 p.
Tên gọi khác	PDSI, Palmer Index, Palmer Drought Index, Self-Calibrating PDSI (sc-PDSI)	Wildland Fire Danger Rating, National Fire-Danger Rating System (NFDRS), Fire Danger Indices, Operational Fire Danger Assessment
Liên quan	2	2
Tóm tắt	The Palmer Drought Severity Index (PDSI), developed by Wayne Palmer in 1965, was the first comprehensive water-balance drought index and remains a benchmark in drought monitoring. Rather than tracking precipitation alone, the PDSI runs a two-layer soil-moisture accounting that balances precipitation against evapotranspiration, runoff, and recharge to gauge whether the moisture supply is abnormally short for the prevailing conditions. It compares actual precipitation to the 'climatically appropriate for existing conditions' (CAFEC) precipitation, converts the departure into a standardized moisture anomaly, and accumulates it over time so that the index reflects the persistence and severity of drought, typically on a scale from about −4 (extreme drought) to +4 (extreme wetness). Because Palmer's original empirical constants were calibrated to particular U.S. regions and limited its spatial comparability, Wells, Goddard, and Hayes introduced the self-calibrating PDSI (sc-PDSI) in 2004, which derives those constants from local data and makes the index far more consistent across climates.	A fire danger rating system converts daily weather, fuel, and topography information into operational indices that summarize how easily wildfires will ignite, spread, and burn intensely. Two systems dominate worldwide practice: the U.S. National Fire-Danger Rating System (NFDRS), documented by Deeming, Burgan, and Cohen, and the Canadian Forest Fire Weather Index (FWI) System, whose structure Van Wagner formalized in 1987. Both begin by tracking the moisture content of fuels of different sizes — fine fuels respond to weather within hours, while heavy logs and deep duff respond over weeks — and then feed these moisture estimates, together with wind and fuel characteristics, through a chain of subindices that estimate rate of spread, fuel consumption, and fire intensity. The end product is a small set of numbers and danger classes (from Low to Extreme) that agencies use to set preparedness levels, issue public warnings, position resources, and impose restrictions.