Person: Ábalos Álvarez, Marta
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First Name
Marta
Last Name
Ábalos Álvarez
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Físicas
Department
Física de la Tierra y Astrofísica
Area
Física de la Tierra
Identifiers
3 results
Search Results
Now showing 1 - 3 of 3
Item Assessing the Projected Changes in European Air Stagnation due to Climate Change(Journal of Climate, 2023) Maddison, Jacob William; Ábalos Álvarez, Marta; Barriopedro Cepero, David; García Herrera, Ricardo Francisco; Garrido Pérez, José Manuel; Ordóñez García, Carlos; Simpson, Isla RAir pollution is a major environmental threat to human health. Pollutants can reach extreme levels in the lower atmosphere when weather conditions permit. As pollutant concentrations depend on scales and processes that are not fully represented in current global circulation models (GCMs), and it is often too computationally expensive to run models with atmospheric chemistry and aerosol processes, air stagnation is often used as a proxy for pollution events with particular success in Europe. However, the variables required to identify air stagnation can have biases in GCM output, which adds uncertainty to projected trends in air stagnation. Here, the representation of air stagnation in GCMs is assessed for Europe in the historical period and in end-of-century projections based on a high-emission scenario using three methods for identifying air stagnation. The monthly frequency of stagnation during summer and autumn is projected to increase with climate change when stagnation is identified by a well-established index. However, this increase is not present when air-stagnation frequency is estimated using a statistical model based on the synoptic- to large-scale atmospheric circulation. This implies that the projected increases in air stagnation are not driven by an increase in frequency or severity of large-scale circulation events that are conducive to stagnation. Indeed, projected changes to the atmospheric circulation in GCMs, in particular a reduction in atmospheric block frequency, would suggest a reduction in future air stagnation. Additional analyses indicate that the projected increases in stagnation frequency follow the trend toward more frequent dry days, which is apparently unrelated to the large-scale drivers of air stagnation.Item Linking air stagnation in Europe with the synoptic- to large-scale atmospheric circulation(Weather and Climate Dynamics, 2021) Maddison, Jacob William; Ábalos Álvarez, Marta; Barriopedro Cepero, David; García Herrera, Ricardo Francisco; Garrido Pérez, José Manuel; Ordóñez García, CarlosThe build-up of pollutants to harmful levels can occur when meteorological conditions favour their production or accumulation near the surface. Such conditions can arise when a region experiences air stagnation. The link between European air stagnation, air pollution and the synoptic- to large-scale circulation is investigated in this article across all seasons and the 1979–2018 period. Dynamical indices identifying atmospheric blocking, Rossby wave breaking, subtropical ridges, and the North Atlantic eddy-driven and subtropical jets are used to describe the synoptic- to large-scale circulation as predictors in statistical models of air stagnation and pollutant variability. It is found that the large-scale circulation can explain approximately 60 % of the variance in monthly air stagnation, ozone and wintertime particulate matter (PM) in five distinct regions within Europe. The variance explained by the model does not vary strongly across regions and seasons, apart from for PM when the skill is highest in winter. However, the dynamical indices most related to air stagnation do depend on region and season. The blocking and Rossby wave breaking predictors tend to be the most important for describing air stagnation and pollutant variability in northern regions, whereas ridges and the subtropical jet are more important to the south. The demonstrated correspondence between air stagnation, pollution and the large-scale circulation can be used to assess the representation of stagnation in climate models, which is key for understanding how air stagnation and its associated climatic impacts may change in the future.Item Quantifying stratospheric biases and identifying their potential sources in subseasonal forecast systems(Weather and Climate Dynamics, 2022) Lawrence, Zachary D.; Ábalos Álvarez, Marta; Ayarzagüena Porras, Blanca; Barriopedro Cepero, David; Calvo Fernández, Natalia; De La Cámara Illescas, Álvaro; Rachel W.-Y. WuThe stratosphere can be a source of predictability for surface weather on timescales of several weeks to months. However, the potential predictive skill gained from stratospheric variability can be limited by biases in the representation of stratospheric processes and the coupling of the stratosphere with surface climate in forecast systems. This study provides a first systematic identification of model biases in the stratosphere across a wide range of subseasonal forecast systems. It is found that many of the forecast systems considered exhibit warm global mean temperature biases from the lower to middle stratosphere, too strong/cold wintertime polar vortices, and too cold extratropical upper troposphere/lower stratosphere regions. Furthermore, tropical stratospheric anomalies associated with the Quasi-Biennial Oscillation tend to decay toward each system's climatology with lead time. In the Northern Hemisphere (NH), most systems do not capture the seasonal cycle of extreme vortex event probabilities, with an underestimation of sudden stratospheric warming events and an overestimation of strong vortex events in January. In the Southern Hemisphere (SH), springtime interannual variability of the polar vortex is generally underestimated, but the timing of the final breakdown of the polar vortex often happens too early in many of the prediction systems. These stratospheric biases tend to be considerably worse in systems with lower model lid heights. In both hemispheres, most systems with low-top atmospheric models also consistently underestimate the upward wave driving that affects the strength of the stratospheric polar vortex. We expect that the biases identified here will help guide model development for sub-seasonal to seasonal forecast systems, and further our understanding of the role of the stratosphere for predictive skill in the troposphere.