Merino et al. (2015) Large-scale patterns of daily precipitation extremes on the Iberian Peninsula

Identification

• Journal: International Journal of Climatology
• Year: 2015
• Date: 2015-12-23
• Authors: Andrés Merino, Mario Fernández-Vaquero, L. López, Sergio Fernández‐González, Lucía Hermida, José Luis Sánchez, Eduardo García‐Ortega, Estíbaliz Gascón
• DOI: 10.1002/joc.4601

Research Groups

• Institute of Geography and Oeschger Centre for Climate Change Research, University of Bern, Switzerland
• Mobiliar Lab for Natural Risks, University of Bern, Switzerland

Short Summary

This study globally quantifies the influence of nine major modes of climate variability on the sub-seasonal temporal clustering of extreme precipitation (TCEP) using Poisson Generalized Linear Models. It reveals that ENSO, the Indian Ocean Dipole (IOD), and the Madden-Julian Oscillation (MJO) are dominant drivers in the tropics, while the North Atlantic Oscillation (NAO) and Pacific North American (PNA) pattern are key in the Northern extratropics, with minimal influence observed in the Southern Hemisphere.

Objective

• To quantify the role of nine major large-scale modes of climate variability on the likelihood of sub-seasonal temporal clustering of extreme precipitation (TCEP) across the globe, analyzing each season separately.

Study Configuration

• Spatial Scale: Global, with detailed analysis across tropical (20°S–20°N) and Northern Hemisphere extratropical regions.
• Temporal Scale: Sub-seasonal (3-week non-overlapping windows), analyzed for each season (DJF, MAM, JJA, SON) over the period 1979–2019.

Methodology and Data

• Models used: Poisson Generalized Linear Models (GLMs) with a forward stepwise covariate selection based on the Akaike Information Criterion (AIC). Model goodness-of-fit was assessed using the deviance ratio (DR) and a chi-square test for Poisson distribution validity.
• Data sources:
  • Daily precipitation data at 1° resolution from the ERA5 reanalysis (1979–2019).
  • Daily indices for NAO, Arctic Oscillation (AO), Southern Annular Mode (SAM), and PNA from NOAA’s Climate Prediction Center.
  • Daily Niño 3.4 and IOD indices calculated from ERA5 sea surface temperature (SST) data.
  • Two real-time multivariate MJO indices (MJO1 and MJO2) from the Australian Bureau of Meteorology.
  • Daily Baroclinic Annular Mode (BAM) index computed from ERA5 6-hourly wind data.

Main Results

• Model goodness-of-fit (DR) is highest in the tropics (20°S–20°N), particularly over the equatorial Pacific, the Maritime Continent, and East Africa, explaining 7–16% of the variance.
• In the tropics, ENSO (Niño 3.4 index) is the dominant driver of TCEP frequency over the tropical Pacific, Maritime Continent, and Southeast Asia.
• The IOD significantly influences TCEP in East Africa, the Sahel (DJF), tropical Indian Ocean (JJA), and Southwest Asia, Indonesia, and Eastern Australia (SON).
• MJO (MJO1 and MJO2) modulates TCEP frequency across much of the tropics, notably over the Arabian Peninsula and Maritime Continent (DJF/MAM for MJO1) and from East Africa to the date line and tropical Americas (JJA for MJO2).
• In the Northern Hemisphere extratropics, the PNA pattern is a dominant influence on TCEP frequency in the North Pacific, Northeastern Asia, Alaska, and the central Pacific Ocean (DJF/MAM).
• The NAO is the prevailing covariate over Greenland and Southwestern Europe, primarily during DJF. The AO index dominates high-latitude regions of North America and Eurasia (DJF/MAM).
• The models show very little skill in the Southern Hemisphere extratropics, consistent with less frequent temporal clustering in these regions.
• The spatiotemporal patterns of TCEP statistical significance identified in previous work largely coincide with regions of high model goodness-of-fit and are primarily linked to IOD, Niño 3.4, PNA, and NAO.

Contributions

• Provides a global and comprehensive analysis of the influence of nine major large-scale modes of climate variability on sub-seasonal TCEP, expanding beyond previous regional studies with fewer modes.
• Establishes that a reduced selection of large-scale climate modes is sufficient to explain a significant portion of the observed temporal clustering of extreme precipitation at the 3-week timescale.
• Offers insights that can contribute to improved sub-seasonal forecasts of TCEP frequency and associated impacts, particularly for modes like ENSO and IOD that are routinely well predicted.

Funding

• Swiss Science Foundation (SNSF) grant number 178751 (for O. Martius).

Citation

@article{Merino2015Largescale,
  author = {Merino, Andrés and Fernández-Vaquero, Mario and López, L. and Fernández‐González, Sergio and Hermida, Lucía and Sánchez, José Luis and García‐Ortega, Eduardo and Gascón, Estíbaliz},
  title = {Large-scale patterns of daily precipitation extremes on the Iberian Peninsula},
  journal = {International Journal of Climatology},
  year = {2015},
  doi = {10.1002/joc.4601},
  url = {https://doi.org/10.1002/joc.4601}
}