Lorente‐Plazas et al. (2019) Unusual Atmospheric‐River‐Like Structures Coming From Africa Induce Extreme Precipitation Over the Western Mediterranean Sea

Identification

• Journal: Journal of Geophysical Research Atmospheres
• Year: 2019
• Date: 2019-12-27
• Authors: Raquel Lorente‐Plazas, Juan Pedro Montávez, Alexandre M. Ramos, Sónia Jerez, Ricardo M. Trigo, Pedro Jiménez‐Guerrero
• DOI: 10.1029/2019jd031280

Research Groups

• Centro de Investigación Mariña, Universidade de Vigo, Environmental Physics Laboratory (EPhysLab), Ourense, Spain

Short Summary

This study globally identifies regions where atmospheric moisture transport (IVT) significantly influences daily extreme precipitation and quantifies the relative importance of its dynamic (wind-related) and thermodynamic (humidity-related) components, highlighting areas where climate change may alter this relationship. It finds that this dependency is weak in tropical regions but strong and non-uniform in extratropical areas, particularly where atmospheric rivers, low-level jets, and tropical cyclones occur.

Objective

• To identify regions globally where atmospheric moisture transport (quantified as Integrated Moisture Vertical Transport, IVT) influences daily extreme precipitation.
• To determine where this influence has a relevant dynamic component, which may alter the dependency between IVT and extreme precipitation as temperatures increase with climate change.
• To estimate the relative influence of the dynamic (IVT/IWV) and thermodynamic (IWV) components of IVT on extreme precipitation.

Study Configuration

• Spatial Scale: Global, gridded data at 0.5° resolution.
• Temporal Scale: Daily values for the period 1981–2020 (40 years), analyzed seasonally (Northern Hemisphere Winter, Spring, Summer, Autumn).

Methodology and Data

• Models used: Extreme Value Theory (EVT), specifically non-stationary Generalized Extreme Value (GEV) models fitted to annual precipitation maxima, with location and scale parameters varying linearly with IVT, IVT/IWV, and IWV. Maximum likelihood fitting using R software (ismev, evd packages).
• Data sources: ERA-5 reanalysis data (Hersbach et al., 2020) for daily precipitation, Integrated Moisture Vertical Transport (IVT), and Integrated Water Vapor (IWV).

Main Results

• The relationship between IVT and daily extreme precipitation is weak or negligible in tropical regions, where high integrated water vapor (IWV) is often sufficient for extreme precipitation.
• In extratropical regions, IVT strongly influences extreme precipitation, with its impact being much greater in areas characterized by major moisture transport mechanisms: atmospheric rivers (ARs), low-level jets (LLJs), and tropical cyclones (TCs).
• The dynamic component of IVT (represented by IVT/IWV, linked to wind) is highly consequential in regions of landfalling ARs (e.g., west coasts of North America, Europe, South America), landfalling TCs (e.g., North American, Southeast Asian coasts), and moisture-transporting LLJs (e.g., Indian monsoon region, southeastern South America).
• In these key regions, the percentage change in the estimated 20-year return levels of maximum precipitation between low and high values of the dynamic component (IVT/IWV) can be approximately 50% or higher.
• In other regions where IVT influences extreme precipitation, this influence is primarily due to the thermodynamic component (IWV).

Contributions

• Provides a global identification of regions and seasons where the link between atmospheric moisture transport and extreme precipitation is most significant.
• Quantifies the distinct roles of the dynamic (wind-related) and thermodynamic (humidity-related) components of moisture transport in influencing extreme precipitation globally.
• Highlights specific areas where the relationship between IVT and extreme precipitation is more susceptible to changes under a warming climate due to the importance of the dynamic component.
• Offers practical implications for improving the predictability of daily precipitation extremes in identified critical regions.

Funding

• SETESTRELO project (grant no. PID2021-122314OB-I00) funded by the Ministerio de Ciencia e Innovación, Spain.
• EPhysLab group co-funded by Xunta de Galicia, Consellería de Cultura, Educación e Universidade, under project ED431C 2021/44 “Programa de Consolidación e Estructuración de Unidades de Investigación Competitivas”.
• Luis Gimeno-Sotelo was supported by a UVigo PhD grant (“Axudas para contratos predoutorais da Universidade de Vigo”).

Citation

@article{LorentePlazas2019Unusual,
  author = {Lorente‐Plazas, Raquel and Montávez, Juan Pedro and Ramos, Alexandre M. and Jerez, Sónia and Trigo, Ricardo M. and Jiménez‐Guerrero, Pedro},
  title = {Unusual Atmospheric‐River‐Like Structures Coming From Africa Induce Extreme Precipitation Over the Western Mediterranean Sea},
  journal = {Journal of Geophysical Research Atmospheres},
  year = {2019},
  doi = {10.1029/2019jd031280},
  url = {https://doi.org/10.1029/2019jd031280}
}