Neto et al. (2025) How does the reference period influence meteorological drought analysis and monitoring? A case study in Northeast Brazil using a century of data

Identification

• Journal: The Science of The Total Environment
• Year: 2025
• Date: 2025-12-09
• Authors: Reginaldo Moura Brasil Neto, Ana Paula Martins do Amaral Cunha, Richarde Marques da Silva, Gabriel de Oliveira
• DOI: 10.1016/j.scitotenv.2025.181124

Research Groups

• Department of Civil and Environmental Engineering, Federal University of Paraíba, Jo˜ao Pessoa, Brazil
• Department of Water Resources Planning, Executive Agency for Water Management of Paraíba, Jo˜ao Pessoa, Brazil
• National Center for Monitoring and Early Warning of Natural Disasters (Cemaden), S˜ao Jos´e dos Campos, Brazil
• Department of Geosciences, Federal University of Paraíba, Jo˜ao Pessoa, Brazil
• Stokes School of Marine and Environmental Sciences, University of South Alabama, Mobile, AL, USA
• Dauphin Island Sea Lab, Dauphin Island, AL, USA

Short Summary

This study investigates how different reference periods influence the identification and characterization of meteorological droughts in Northeast Brazil using the Standardized Precipitation Index (SPI) over a century of data, finding that short (10-year) and long (100-year) periods distort drought classification, while 20-year and 40-year periods best match the conventional 30-year baseline.

Objective

• To examine how different reference periods influence the identification and characterization of recent meteorological droughts (2010–2019) in Northeast Brazil (NEB) using the Standardized Precipitation Index (SPI).

Study Configuration

• Spatial Scale: Northeast Brazil (NEB), analyzed at grid and state scales.
• Temporal Scale: Century-long data (1920–2019) for analysis, with recent droughts (2010–2019) as a case study. Drought metrics evaluated at monthly, quarterly, semiannual, and annual temporal scales. Nine alternative reference periods (10–100 years) compared against a conventional 30-year period.

Methodology and Data

• Models used: Standardized Precipitation Index (SPI).
• Data sources: 602 precipitation series from the Climate Research Unit (CRU).

Main Results

• During 2010–2019, several states in NEB experienced drought in more than 80% of events, with over 10% classified as extremely dry under SPI-12.
• Average drought duration exceeded 36 months in multiple states, and mean intensity approached 1.5 per month.
• Reference period scenarios S2 (20 years) and S4 (40 years) best matched the 30-year baseline, with R, Kd, and Kp values above 0.80 and RMSE below 0.20.
• Shorter (10 years) and longer (100 years) reference periods distorted drought classification and misguided monitoring.
• Longer scenarios overestimated drought duration by more than 10 months and severity by more than 10 SPI units.

Contributions

• Novel comparison of nine temporal scenarios against the conventional 30-year baseline for drought monitoring.
• Provides a transferable framework and guidance for drought monitoring, particularly in data-scarce regions.
• Highlights the sensitivity of drought analysis to the chosen reference period, offering insights for public policy and monitoring strategies.

Funding

• Not explicitly stated in the provided text.

Citation

@article{Neto2025How,
  author = {Neto, Reginaldo Moura Brasil and Cunha, Ana Paula Martins do Amaral and Silva, Richarde Marques da and Oliveira, Gabriel de and Santos, Celso Augusto Guimarães},
  title = {How does the reference period influence meteorological drought analysis and monitoring? A case study in Northeast Brazil using a century of data},
  journal = {The Science of The Total Environment},
  year = {2025},
  doi = {10.1016/j.scitotenv.2025.181124},
  url = {https://doi.org/10.1016/j.scitotenv.2025.181124}
}