Anahí Villalba-Pradas

Stratosphere-troposphere exchange (STE) plays a fundamental role in the global atmospheric budget of chemical constituents. The troposphere-to-stratosphere transport (TST), as a part of STE, can inject anthropogenic pollutants from the Earth’s surface into the stratosphere, changing its chemical composition and influencing radiative processes. On record, TST is a multi-scale process with various contributing mechanisms, often not fully qualified nor quantified. In the tropics, typhoons and the corresponding overshooting convection and updrafts have recently been highlighted as one of the TST mechanisms, contributing for instance to the moistening of the lower stratosphere. Expanding on this, our study proposes a novel mechanism for TST connected with the interaction of typhoons with orography, including modulation of typhoon updrafts and convection, orographic lifting, and orographic gravity waves. Combining a Lagrangian modeling tool with a high-resolution simulation of the landfall of typhoon Molave (2020) in the Philippines, our results show that the presence of orography enhances the transport of air from the planetary boundary layer to the upper troposphere–lower stratosphere (UTLS) region. The presented findings advance our understanding of tropical cyclones impacts on STE and may have significant implications for the long-range atmospheric transport of pollutants originating from tropics.

Stratosphere-troposphere exchange (STE) plays a fundamental role in the global atmospheric budget of chemical constituents. The troposphere-to-stratosphere transport (TST), as a part of STE, can inject anthropogenic pollutants from the Earth’s surface into the stratosphere, changing its chemical composition and influencing radiative processes. On record, TST is a multi-scale process with various contributing mechanisms, often not fully qualified nor quantified. In the tropics, typhoons and the corresponding overshooting convection and updrafts have recently been highlighted as one of the TST mechanisms, contributing for instance to the moistening of the lower stratosphere. Expanding on this, our study proposes a novel mechanism for TST connected with the interaction of typhoons with orography, including modulation of typhoon updrafts and convection, orographic lifting, and orographic gravity waves. Combining a Lagrangian modeling tool with a high-resolution simulation of the landfall of typhoon Molave (2020) in the Philippines, our results show that the presence of orography enhances the transport of air from the planetary boundary layer to the Upper Troposphere–Lower Stratosphere region. The presented findings have broad implications for topics of high social importance, such as the long-range dispersion of pollutants.

Stratosphere-troposphere exchange (STE) plays a fundamental role in the global atmospheric budget of chemical constituents. The troposphere-to-stratosphere transport (TST), as a part of STE, can inject anthropogenic pollutants from the Earth’s surface into the stratosphere, changing its chemical composition and influencing radiative processes. On record, TST is a multi-scale process with various contributing mechanisms, often not fully qualified nor quantified. In the tropics, typhoons and the corresponding overshooting convection and updrafts have recently been highlighted as one of the TST mechanisms, contributing for instance to the moistening of the lower stratosphere. Expanding on this, our study proposes a novel mechanism for TST connected with the interaction of typhoons with orography, including modulation of typhoon updrafts and convection, orographic lifting, and orographic gravity waves. Combining a Lagrangian modeling tool with a high-resolution simulation of the landfall of typhoon Molave (2020) in the Philippines, our results show that the presence of orography enhances the transport of air from the planetary boundary layer to the Upper Troposphere–Lower Stratosphere region. The presented findings have broad implications for topics of high social importance, such as the long-range dispersion of pollutants.

Stratosphere-troposphere exchange (STE) plays a fundamental role in the global atmospheric budget of chemical constituents. The troposphere-to-stratosphere transport (TST), as a part of STE, can inject anthropogenic pollutants from the Earth’s surface into the stratosphere, changing its chemical composition and influencing radiative processes. On record, TST is a multi-scale process with various contributing mechanisms, often not fully qualified nor quantified. In the tropics, typhoons and the corresponding overshooting convection and updrafts have recently been highlighted as one of the TST mechanisms, contributing for instance to the moistening of the lower stratosphere. Expanding on this, our study proposes a novel mechanism for TST connected with the interaction of typhoons with orography, including modulation of typhoon updrafts and convection, orographic lifting, and orographic gravity waves. Combining a Lagrangian modeling tool with a high-resolution simulation of the landfall of typhoon Molave (2020) in the Philippines, our results show that the presence of orography enhances the transport of air from the planetary boundary layer to the Upper Troposphere–Lower Stratosphere region. The presented findings have broad implications for topics of high social importance, such as the long-range dispersion of pollutants.

Urban environments are hotspots of anthropogenic emissions, impact the warming rate over cities, and induce changes in several relevant meteorological variables such as wind speed, humidity and temperature, which in turn affect air quality and human health. Therefore, it is important to identify how urban parameterizations impact the regional-to-local scale processes in regional climate model simulations. To evaluate these impacts, we use the Weather Research and Forecasting (WRF) model with different urban schemes. The simulated period covers a timespan of 10 year and has an especial focus on the city of Prague (Czech Republic). To evaluate the results obtained, data from observations from the Czech Hydrometeorological Institute were used. Changes in temperature and specific humidity are mostly sensitive to the urban scheme selected, while changes in precipitation and cloud cover are less sensitive to the urban parameterization but more sensitive to the parameterization of convection and microphysics.

Troposphere-to-Stratosphere Transport (TST) can inject anthropogenic pollutants from the Earth’s surface into the Upper Troposphere – Lower Stratosphere (UTLS), changing its chemical composition and influencing the radiative processes. Furthermore, TST may play a key role in sustaining the long-range transport of pollutants across the globe, particularly during extreme weather events. Indeed, during such events, a large quantity of pollutants can be transported from the Boundary Layer (BL) to the free atmosphere, enhancing the probability of long-range transport as the contaminants reach higher altitudes. The various mechanisms that contribute to TST have not yet been fully resolved due to the multi-scale nature of this transport process. In our study, we investigated the TST processes triggered by the transition of the typhoon Molave over the Philippines in the autumn 2020, combining a Lagrangian modeling tool with the Weather Research and Forecasting model. Our findings supported the proposal of a novel TST mechanism based on the interaction between typhoon updrafts, convection, orographic lifting, and gravity waves. Firstly, our results demonstrate that this interaction can rapidly transport air from the BL to the UTLS region, carrying a significant amount of pollutants despite deposition processes. Secondly, our work highlights the importance of gravity waves in the mixing processes close to the tropopause region. Overall, our study suggests that the interplay between typhoon episodes and mountainous regions can play an important, yet previously insufficiently considered, role in TST. This interaction influences key topics that are relevant to our society, such as the long-range dispersion of pollutants.

Stratosphere-troposphere exchange (STE) plays a fundamental role in the global atmospheric budget of chemical constituents. The troposphere-to-stratosphere transport (TST), as a part of STE, can inject anthropogenic pollutants from the Earth’s surface into the stratosphere, changing its chemical composition and influencing radiative processes. On record, TST is a multi-scale process with various contributing mechanisms, often not fully qualified nor quantified. In the tropics, typhoons and the corresponding overshooting convection and updrafts have recently been highlighted as one of the TST mechanisms, contributing for instance to the moistening of the lower stratosphere. Expanding on this, our study proposes a novel mechanism for TST connected with the interaction of typhoons with orography, including modulation of typhoon updrafts and convection, orographic lifting, and orographic gravity waves. Combining a Lagrangian modeling tool with a high-resolution simulation of the landfall of typhoon Molave (2020) in the Philippines, our results show that the presence of orography enhances the transport of air from the planetary boundary layer to the Upper Troposphere–Lower Stratosphere region. The presented findings have broad implications for topics of high social importance, such as the long-range dispersion of pollutants.

The impact of urban areas on relevant meteorological variables, especially on temperature and wind speed, is well‐known, and several studies have evaluated this effect. However, fewer of them have focused on the effect of urban areas on cloud cover and precipitation. To evaluate this, a total of 15 simulations were performed using the Weather Research and Forecasting model on a Central European domain at 9−km horizontal resolution. The novelty of this study is the number of cities considered and ensembles used over a 10‐year period including not only the impacts of the urban scheme but also the effects of two other relevant parameterizations, namely, convection and microphysics, on the representation of the urban meteorology island (UMI) variables with a special focus on less studied variables, that is, cloud cover and precipitation. Our results show that changes in temperature and specific humidity are mostly sensitive to the urban scheme selected, while changes in precipitation and cloud cover are more sensitive to the parameterization of convection and microphysics. The cloud cover strongly depends on the convection and microphysics schemes, especially in summer (JJA), although the impacts of the different parameterizations depend on the selected city. Despite differences observed among cities, cloud cover increases over urban areas during the afternoon and evening and decreases during the morning and night, especially in JJA. The selection of both convection and microphysics schemes plays an important role in the simulated precipitation. In winter (DJF), no significant variation between simulations is observed. On the other hand, precipitation is enhanced over urban areas during JJA. This study highlights the importance of using model ensembles and a number of cities when evaluating the urban heat island and UMI meteorological values, as large differences exist between the different setups and selected cities.

The Work Package 4 of the FOCI project (“Non-CO2 Forcers and their Climate, Weather, Air Quality and Health Impacts”, https://www.project-foci.eu/wp/) is responsible for tuning, testing, and conducting long-term simulations to validate various regional models in downscaling of reanalysis and global climate models for historical period. The long-term simulations are performed by RegCM5-Chem and WRF-Chem, i.e., coupled with chemistry over the European domain. It is important to highlight here the use of RegCM5-Chem for the long-term simulation with full chemistry has been a novelty in the community. Since its previous version (RegCM4-Chem), the tropospheric gas-phase chemistry was introduced using the Carbon Bond Mechanism Z (CBM-Z) chemistry mechanism. This enabled for interactive coupling between the modelled ozone and its radiative effects as well as coupling between the gas-phase chemical processes and aerosol formation (production of nitrates and sulphates). The initial and boundary conditions for the atmospheric variables and chemical composition were created from the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis version 5 (ERA5) and Atmospheric Composition Reanalysis 4 (EAC4) datasets. The emissions of atmospheric pollutants and greenhouse gases are taken from the Copernicus Atmosphere Monitoring Service (CAMS) high-resolution European emission inventory for air quality modelling. The CAMS Regional European air quality reanalyses are used for validating the outputs. Preliminary results for one year simulation show that both models underestimate particulate matter concentrations over the domain in boreal summer. Nitrogen dioxide is mostly overestimated by RegCM-Chem and the opposite occurs in WRF-Chem. Ozone is generally underestimated by both models but overestimated southern 50°N in RegCM-Chem. The long-term evaluation will consider further species, such as methane and sulphur dioxide, and will be represented in terms of seasonal biases regarding the observations.

Work Package 4 of the FOCI project (“Non-CO2 Forcers and their Climate, Weather, Air Quality and Health Impacts”; https://www.project-foci.eu/wp/) is tasked with tuning, testing, and conducting long-term simulations to validate various regional models in downscaling of reanalysis and global climate models for historical period. The long-term simulations are performed by RegCM5-Chem and WRF-Chem, both of which are coupled with chemistry over the European domain. A notable aspect of this work is the use of RegCM5-Chem for long-term simulations, which is a novel approach within the community. Besides that, the land cover is dynamic, derived from the Land Use and Climate Across Scales flagship pilot study of the EURO-CORDEX initiative. The initial and boundary conditions for the atmospheric variables and chemical composition were created from the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis version 5 (ERA5) and Atmospheric Composition Reanalysis 4 (EAC4) datasets. Emissions of atmospheric pollutants and greenhouse gases are obtained from the Copernicus Atmosphere Monitoring Service (CAMS) high-resolution European emission inventory for air quality modeling. E-OBS is utilized for validating the outputs. Sensitivity tests have shown that coupled chemistry impacts surface meteorological variables, such as temperature and shortwave radiation. In this study, we will evaluate these variables in greater detail, as well as examine how this coupling affects precipitation and surface wind speed. It is important to note that the chemical mechanism enables interactive coupling between modeled ozone and its radiative effects, as well as between gas-phase chemical processes and aerosol formation. These interactions, in turn, have feedback on the radiative, thermodynamic, and dynamic fields. This evaluation is crucial for enabling further comparisons with simulations driven by EC-Earth-AerChem in both present and future climates, as part of FOCI Work Package 6.