By ESS team

    • A new analysis of atmospheric circulation patterns in the Mediterranean and their impact on temperature and precipitation in the Iberian Peninsula on different time scales has been recently published.
    • The study shows that atmospheric patterns―favouring hot, dry days―turned out to be increasingly recurrent which might be related to the persistence of warmer and drier conditions in recent years, especially in Catalonia.
    • The research has been led by the Earth System Services group of the Barcelona Supercomputing Center.

The Earth System Services (ESS) group at the Earth Sciences Department of the Barcelona Supercomputing Center-Centro Nacional de Supercomputación (BSC-CNS) has recently published a new study that presents a framework to assess climate variability and change through atmospheric circulation patterns and their link with regional processes across time scales.

The research team, led by climate researcher Matías Olmo (ESS group), evaluated the atmospheric circulation pattern impacts on daily rainfall and maximum and minimum temperatures in the Iberian Peninsula. An atmospheric pattern refers to the shape and intensity of the atmospheric pressure over the Mediterranean on a given day. Thus, for example, when there are high-pressure systems over the Iberian Peninsula, the warmth and lack of precipitation in the region tend to be more favourable. 

The study allowed the identification of atmospheric configurations significantly related to discriminated precipitation and temperature anomalies, with a clear seasonal behaviour. The temporal variability of circulation patterns was studied across time scales showing, for example, that transitions between patterns were faster in autumn and spring, and that circulation patterns showed distinct temporal variability at intraseasonal, seasonal, interannual and decadal scales, including significant long-term trends in their frequency. 

One of the results from the circulation patterns analysis throughout the year is that the winter presented the highest atmospheric circulation variability. At the same time, summer was dominated by persistent high-pressure structures―the Azores subtropical high―that led to warm and dry conditions. Based on an interannual correlation analysis, some circulation patterns were significantly associated with the North Atlantic Oscillation (NAO), a relationship that is stronger during winter, indicating the modulation of the NAO on regional to local climate characteristics. 

Figure. Atmospheric circulation pattern through the sea level pressure.

Olmo stated: “Overall, this approach arises as a dynamic cross-time-scale framework that can be adapted to specific user needs and levels of regional detail.” He added: “This kind of analysis is useful to study climate drivers for climate change and to perform a process-based evaluation of climate models, which can help to quantify the uncertainty in future projections.”


The work stems from a collaboration between the BSC and the Meteorological Service of Catalonia (METEOCAT), which aims to study changes in the Mediterranean and Catalonia's climate in the context of global warming. The working group's follow-up analyses involve studies of the attribution of climate events and trends and uncertainty about what is expected for the future.

Reference

Olmo, M., Cos, P., Múñoz, A.G., et al., Cross-Time-Scale Analysis of Year-Round Atmospheric Circulation Patterns and Their Impacts on Rainfall and Temperatures in the Iberian Peninsula, Journal of Climate, 5525-5541, 2024. https://doi.org/10.1175/JCLI-D-23-0735.1.