Person:
Ábalos Álvarez, Marta

First Name

Marta

Last Name

Ábalos Álvarez

URI

https://hdl.handle.net/20.500.14352/75077

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Ciencias Físicas

Department

Física de la Tierra y Astrofísica

Area

Física de la Tierra

Identifiers

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Now showing 1 - 10 of 13

Linking air stagnation in Europe with the synoptic- to large-scale atmospheric circulation
(Weather and Climate Dynamics, 2021) Maddison, Jacob W; Ábalos Álvarez, Marta; Barriopedro Cepero, David; García Herrera, Ricardo Francisco; Garrido Pérez, José Manuel; Ordóñez García, Carlos
The 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.
Upwelling in the tropical lower stratosphere: effects on tracer transport and drivers of variability
(2014) Ábalos Álvarez, Marta; Serrano Mendoza, Encarna; Randel, William J.
Inconsistencies between chemistry-climate models and observed lower stratospheric ozone trends since 1998
(Atmospheric chemistry and physics, 2020) Ball, William T.; Chiodo, Gabriel; Ábalos Álvarez, Marta; Alsing, Justin; Stenke, Andrea
The stratospheric ozone layer shields surface life from harmful ultraviolet radiation. Following the Montreal Protocol ban on long-lived ozone-depleting substances (ODSs), rapid depletion of total column ozone (TCO) ceased in the late 1990s, and ozone above 32 km is now clearly recovering. However, there is still no confirmation of TCO recovery, and evidence has emerged that ongoing quasiglobal (60◦ S–60◦ N) lower stratospheric ozone decreases may be responsible, dominated by low latitudes (30◦ S– 30◦ N). Chemistry–climate models (CCMs) used to project future changes predict that lower stratospheric ozone will decrease in the tropics by 2100 but not at mid-latitudes (30–60◦ ). Here, we show that CCMs display an ozone decline similar to that observed in the tropics over 1998–2016, likely driven by an increase in tropical upwelling. On the other hand, mid-latitude lower stratospheric ozone is observed to decrease, while CCMs that specify real-world historical meteorological fields instead show an increase up to present day. However, these cannot be used to simulate future changes; we demonstrate here that free-running CCMs used for projections also show increases. Despite opposing lower stratospheric ozone changes, which should induce opposite temperature trends, CCMs and observed temperature trends agree; we demonstrate that opposing model– observation stratospheric water vapour (SWV) trends, and their associated radiative effects, explain why temperature changes agree in spite of opposing ozone trends. We provide new evidence that the observed mid-latitude trends can be explained by enhanced mixing between the tropics and extratropics. We further show that the temperature trends are consistent with the observed mid-latitude ozone decrease. Together, our results suggest that large-scale circulation changes expected in the future from increased greenhouse gases (GHGs) may now already be underway but that most CCMs do not simulate mid-latitude ozone layer changes well. However, it is important to emphasise that the periods considered here are short, and internal variability that is both intrinsic to each CCM and different to observed historical variability is not well-characterised and can influence trend estimates. Nevertheless, the reason CCMs do not exhibit the observed changes needs to be identified to allow models to be improved in order to build confidence in future projections of the ozone layer.
Boreal winter stratospheric climatology in EC-EARTH: CMIP6 version
(Climate dynamics, 2022) Palmeiro, Froila M.; García Serrano, Javier; Rodrigo, Mario; Ábalos Álvarez, Marta; Christiansen, Bo; Yang, Shuting
The performance of the European Consortium Earth-system model (EC-EARTH) in the boreal winter stratosphere is comprehensively assessed for the first time, in particular its version 3.3 that contributes to CMIP6. A 100-year long simulation with prescribed climatological boundary conditions and fixed radiative forcing, representative of present-day climate, is used to evaluate the simulation of the climatological stratospheric circulation and to identify model biases. Results show that EC-EARTH has a large issue with the vertical distribution of stratospheric temperature from the tropics to mid-latitudes, seemingly linked to radiative processes of ozone, leading to a biased warm middle-upper stratosphere. Associated with this model bias, EC-EARTH simulates a stronger polar vortex at upper-stratospheric levels while the Brewer-Dobson circulation at middle/lower levels is weaker than reanalysis. The amplitude of the climatological planetary waves is overall underestimated, but the magnitude of the background wave injection from the troposphere into the stratosphere is overestimated, related to a weaker polar vortex at lower-stratospheric levels and, thus, a less effective wave filtering. This bias in the westerly flow could have a contribution from parameterized waves. The overestimation of background wave driving is maximum in early-winter, and may explain the overestimated frequency of sudden stratospheric warmings at this time, as compared to reanalysis. The spatial distribution of wave injection climatology has revealed a distinctive role of the climatological planetary waves: while large-scale waves (wavenumbers 1-2) dominate the eddy heat flux over the North Pacific, small-scale waves (wavenumbers 3-4) are responsible for the doubled-lobe structure of the eddy heat flux over Eurasia. EC-EARTH properly simulates this climatological feature, although overestimates its amplitude over central Eurasia.
Stratospheric connection to the abrupt end of the 2016/2017 iberian drought
(Geophysical Research Letters, 2018) Ayargüena Porras, Blanca; Barriopedro Cepero, David; Garrido Pérez, José Manuel; Ábalos Álvarez, Marta; De La Cámara Illescas, Álvaro; García Herrera, Ricardo Francisco; Calvo, N.; Ordóñez García, Carlos; Ayarzagüena Porras, Blanca
Southwestern Europe experienced extraordinary rainy and windy conditions in March 2018, leading to the end of the most severe drought since 1970 at continental scale. This anomalous weather was linked to a persistent negative North Atlantic Oscillation pattern. Two weeks earlier a sudden stratospheric warming (SSW) took place, preceded by the strongest planetary wave activity on record. In this study, we explore the connection between the SSW and the weather shift by employing a weather regime approach and flow analogues. The timing of the downward propagation of the stratospheric anomalies, the transition to and persistence of the negative North Atlantic Oscillation weather regime, and the sudden precipitation increase are all consistent with the typical tropospheric state after SSWs. Our results evidence a significant role of the 2018 SSW in the record-breaking precipitation event.
Assessing the Projected Changes in European Air Stagnation due to Climate Change
(Journal of Climate, 2023) Maddison, Jacob W; Ábalos Álvarez, Marta; Barriopedro Cepero, David; García Herrera, Ricardo Francisco; Garrido Pérez, José Manuel; Ordóñez García, Carlos; Simpson, Isla R
Air 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.
New Insights on the Impact of Ozone-Depleting Substances on the Brewer-Dobson Circulation
(Journal of geophysical research-atmospheres, 2019) Ábalos Álvarez, Marta; Polvani, Lorenzo; Calvo Fernández, Natalia; Kinnison, Douglas; Ploeger, Felix; Randel, William; Solomon, Susan
It has recently been recognized that, in addition to greenhouse gases, anthropogenic emissions of ozone-depleting substances (ODS) can induce long-term trends in the Brewer-Dobson circulation (BDC). Several studies have shown that a substantial fraction of the residual circulation acceleration over the last decades of the twentieth century can be attributed to increasing ODS. Here the mechanisms of this influence are examined, comparing model runs to reanalysis data and evaluating separately the residual circulation and mixing contributions to the mean age of air trends. The effects of ozone depletion in the Antarctic lower stratosphere are found to dominate the ODS impact on the BDC, while the direct radiative impact of these substances is negligible over the period of study. We find qualitative agreement in austral summer BDC trends between model and reanalysis data and show that ODS are the main driver of both residual circulation and isentropic mixing trends over the last decades of the twentieth century. Moreover, aging by isentropic mixing is shown to play a key role on ODS-driven age of air trends.
Response of Arctic ozone to sudden stratospheric warmings
(Atmospheric Chemistry and Physics, 2018) Cámara Illescas, Álvaro de la; Ábalos Álvarez, Marta; Hitchcock, Peter; Calvo Fernández, Natalia; García, Rolando R.
Sudden stratospheric warmings (SSWs) are the main source of intra-seasonal and interannual variability in the extratropical stratosphere. The profound alterations to the stratospheric circulation that accompany such events produce rapid changes in the atmospheric composition. The goal of this study is to deepen our understanding of the dynamics that control changes of Arctic ozone during the life cycle of SSWs, providing a quantitative analysis of advective transport and mixing. We use output from four ensemble members (60 years each) of the Whole Atmospheric Community Climate Model version 4 performed for the Chemistry Climate Model Initiative and also use reanalysis and satellite data for validation purposes. The composite evolution of ozone displays positive mixing ratio anomalies of up to 0.5-0.6 ppmv above 550 K (similar to 50 hPa) around the central warming date and negative anomalies below (-0.2 to -0.3 ppmv), consistently in observations, reanalysis, and the model. Our analysis shows a clear temporal offset between ozone eddy transport and diffusive ozone fluxes. The initial changes in ozone are mainly driven by isentropic eddy fluxes linked to enhanced wave drag responsible for the SSW. The recovery of climatological values in the aftermath of SSWs is slower in the lower than in the upper stratosphere and is driven by the competing effects of cross-isentropic motions (which work towards the recovery) and isentropic irreversible mixing (which delays the recovery). These features are enhanced in strength and duration during sufficiently deep SSWs, particularly those followed by polar-night jet oscillation (PJO) events. It is found that SSW-induced ozone concentration anomalies below 600 K (similar to 40 hPa), as well as total column estimates, persist around 1 month longer in PJO than in non-PJO warmings.
Very short-lived halogens amplify ozone depletion trends in the tropical lower stratosphere
(Nature Climate Change, 2023) Ábalos Álvarez, Marta; Villamayor, Julián; Iglesias-Suarez, Fernando; Cuevas, Carlos A.; Fernandez, Rafael P.; Abalos Álvarez, Marta; Li, Qiny; Hossaini, Ryan; Chipperfield, Martyn P.; Kinnison, Douglas E.; Tilmes, Simone; Lamarque, Jean-Francois; Saiz-Lopez, Alfonso
In contrast to the general stratospheric ozone recovery following international agreements, recent observations show an ongoing net ozone epletion in the tropical lower stratosphere (LS). This depletion is thought to be driven by dynamical transport accelerated by global warming, while chemical processes have been considered to be unimportant. Here we use a chemistry–climate model to demonstrate that halogenated ozone-depleting very short-lived substances (VSLS) chemistry may account for around a quarter of the observed tropical LS negative ozone trend in 1998–2018. VSLS sources include both natural and anthropogenic emissions. Future projections show the persistence of the currently unaccounted for contribution of VSLS to ozone loss throughout the twenty-first century in the tropical LS, the only region of the global stratosphere not projecting an ozone recovery by 2100. Our results show the need for mitigation strategies of anthropogenic VSLS emissions to preserve the present and future ozone layer in low latitudes.
Fast transport pathways into the northern hemisphere upper troposphere and lower stratosphere during northern summer
(Journal of geophysical research-atmospheres, 2020) Wu, Yutian; Orbe, Clara; Tilme, Simone; Ábalos Álvarez, Marta; Wang, Xinyue
This study identifies the fast (i.e., ∼ days–weeks) transport pathways that connect the Northern Hemisphere surface to the upper troposphere and lower stratosphere (UTLS) during northern summer by integrating a large (90 member) ensemble of Boundary Impulse Response tracers in the Whole Atmosphere Community Climate Model version 5. We show that there is a fast transport pathway that occurs over the southern slope of the Tibetan Plateau, northern India, the Arabian Sea, and Saudi Arabia; furthermore, we show that during July this pathway connects the Northern Hemisphere surface to the UTLS on a modal time scale of 5–10 days. A less efficient transport pathway is also identified over the western Pacific. A detailed budget analysis reveals that, while convective processes are responsible for transport to 200–300 hPa, the resolved dynamics, specifically the vertical eddy flux, dominate at 100–150 hPa. Transport variations are analyzed on weekly, monthly, and interannual time scales and are largely related to differences in the resolved dynamics in the UTLS.