A5017289842- Atmospheric Ozone and Climate
- Atmospheric and Environmental Gas Dynamics
- Atmospheric chemistry and aerosols
- Solar Radiation and Photovoltaics
- Solar and Space Plasma Dynamics
- Climate variability and models
- Calibration and Measurement Techniques
- Meteorological Phenomena and Simulations
- Ionosphere and magnetosphere dynamics
- Climate Change and Geoengineering
- Air Quality Monitoring and Forecasting
- Ocean Acidification Effects and Responses
- Geophysics and Gravity Measurements
- Astro and Planetary Science
- Spectroscopy and Laser Applications
- Scientific Computing and Data Management
- Water Quality Monitoring and Analysis
- Interdisciplinary Research and Collaboration
- Cryospheric studies and observations
- Gas Dynamics and Kinetic Theory
- Contemporary and Historical Greek Studies
- Plasma and Flow Control in Aerodynamics
- Reflective Practices in Education
- Research in Social Sciences
- Innovative Teaching and Learning Methods
ETH Zurich
2016-2024
Physikalisch-Meteorologisches Observatorium Davos
2015-2024
Delft University of Technology
2020-2024
École Polytechnique Fédérale de Lausanne
2020
Imperial College London
2011-2014
Kyung Hee University
2014
Kitt Peak National Observatory
1990
Abstract. Ozone forms in the Earth's atmosphere from photodissociation of molecular oxygen, primarily tropical stratosphere. It is then transported to extratropics by Brewer–Dobson circulation (BDC), forming a protective ozone layer around globe. Human emissions halogen-containing ozone-depleting substances (hODSs) led decline stratospheric until they were banned Montreal Protocol, and since 1998 upper stratosphere rising again, likely recovery halogen-induced losses. Total column...
Abstract. The enhancement of the stratospheric aerosol layer by volcanic eruptions induces a complex set responses causing global and regional climate effects on broad range timescales. Uncertainties exist regarding climatic response to strong forcing identified in coupled simulations that contributed fifth phase Coupled Model Intercomparison Project (CMIP5). In order better understand sources these model diversities, Volcanic (VolMIP) has defined coordinated idealized perturbation...
Abstract. The Montreal Protocol, and its subsequent amendments, has successfully prevented catastrophic losses of stratospheric ozone, signs recovery are now evident. Nevertheless, recent work suggested that ozone in the lower stratosphere (< 24 km) continued to decline over 1998–2016 period, offsetting at higher altitudes preventing a statistically significant increase quasi-global (60∘ S–60∘ N) total column ozone. In 2017, large resurgence less than 12 months was estimated (using...
Context: The study of variations in total solar irradiance (TSI) is important for understanding how the Sun affects Earth's climate. Aims: Full-disk continuum images and magnetograms are now available three full cycles. We investigate modelled TSI compares with direct observations by building a consistent dataset. model, based only on changes photospheric magnetic flux can then be tested rotational, cyclical secular timescales. Methods: use Kitt Peak SoHO/MDI SATIRE-S model to reconstruct...
The Sun and stars with low magnetic activity levels, become photometrically brighter when their increases. Magnetically more active display the opposite behaviour get fainter We reproduce observed photometric trends in stellar variations a model that treats as hypothetical Suns coverage by features different from of Sun. presented attributes variability spectra to imbalance between contributions components solar atmosphere, such dark starspots bright faculae. A spectrum is calculated...
Abstract. We compare simulations from three high-top (with upper lid above 120 km) and five medium-top around 80 atmospheric models with observations of odd nitrogen (NOx = NO + NO2), temperature, carbon monoxide seven satellite instruments (ACE-FTS on SciSat, GOMOS, MIPAS, SCIAMACHY Envisat, MLS Aura, SABER TIMED, SMR Odin) during the Northern Hemisphere (NH) polar winter 2008/2009. The included in comparison are 3-D chemistry transport model 3dCTM, ECHAM5/MESSy Atmospheric Chemistry (EMAC)...
Abstract. The eruption of Mt. Tambora in 1815 was the largest volcanic past 500 years. had significant climatic impacts, leading to 1816 year without a summer, and remains valuable event from which understand effects large stratospheric sulfur dioxide injections. also resulted one strongest most easily identifiable sulfate signals polar ice cores, are widely used reconstruct timing atmospheric loading eruptions. As part Model Intercomparison Project on response Volcanic forcing (VolMIP),...
Abstract. 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 (TCO) ceased in late 1990s, and above 32 km is now clearly recovering. However, there still no confirmation TCO recovery, evidence has emerged that ongoing quasi-global (60∘ S–60∘ N) lower decreases may be responsible, dominated by low latitudes (30∘ S–30∘ N). Chemistry–climate...
Abstract. Recent observations show a significant decrease in lower-stratospheric (LS) ozone concentrations tropical and mid-latitude regions since 1998. By analysing 31 chemistry climate model (CCM) simulations performed for the Chemistry Climate Model Initiative (CCMI; Morgenstern et al., 2017), we find large spread 1998–2018 trend patterns between different CCMs realizations with same CCM. The latter particular indicates that natural variability strongly influences LS trends. However none...
Abstract. As part of the Model Intercomparison Project on climatic response to Volcanic forcing (VolMIP), several climate modeling centers performed a coordinated pre-study experiment with interactive stratospheric aerosol models simulating volcanic cloud from an eruption resembling 1815 Mt. Tambora (VolMIP-Tambora ISA ensemble). The provided ancillary ability assess intermodel diversity in radiative for large stratospheric-injecting equatorial when is simulated interactively. An initial...
Abstract Sporadic solar energetic particle (SEP) events affect the Earth’s atmosphere and environment, in particular leading to depletion of protective ozone layer atmosphere, pose potential technological even life hazards. The greatest SEP storm known for last 11 millennia (the Holocene) occurred 774–775 AD, serving as a likely worst-case scenario being 40–50 times stronger than any directly observed one. Here we present systematic analysis impact such an extreme event can have on...
Abstract An accurate quantification of the stratospheric ozone feedback in climate change simulations requires knowledge response to increased greenhouse gases. Here, an analysis is presented layer abrupt quadrupling CO2 concentrations four chemistry–climate models. The authors show that levels lead a decrease tropical lower stratosphere, and increase over high latitudes throughout upper stratosphere. This pattern robust across all models examined here, although important intermodel...
Abstract Up to now our understanding of the 11 year ozone solar cycle signal (SCS) in upper stratosphere has been largely based on Stratospheric Aerosol and Gas Experiment (SAGE) II (v6.2) data record, which indicated a large positive could not be reproduced by models, calling into question chemistry stratosphere. Here we present an analysis new v7.0 SAGE shows smaller SCS, due more realistic ozone‐temperature anticorrelation. New simulations from state‐of‐art 3‐D chemical transport model...
Future increases in stratospheric water vapour risk amplifying climate change and slowing down the recovery of ozone layer. However, state-of-the-art models strongly disagree on magnitude these under global warming. Uncertainty primarily arises from complex processes leading to dehydration air during its tropical ascent into stratosphere. Here we derive an observational constraint this longstanding uncertainty. We use a statistical-learning approach infer historical co-variations between...
Abstract The state of the stratospheric ozone layer and temperature structure atmosphere are largely controlled by solar spectral irradiance (SSI) through its influence on heating photolysis rates. This study focuses uncertainties in rate response to variability related choice SSI data set performance codes used global chemistry‐climate models. To estimate impact uncertainties, we compared several rates calculated with radiative transfer model libRadtran, using two models observed during...
Abstract Total solar irradiance and UV spectral has been monitored since 1978 through a succession of space missions. This is accompanied by the development models aimed at replicating relating variability to magnetic activity. The Naval Research Laboratory Solar Spectral Irradiance (NRLSSI) And REconstruction for Satellite era (SATIRE‐S) provide most comprehensive reconstructions total over period satellite observation currently available. There persistent controversy between various...
Aims: We investigate how well modeled solar irradiances agree with measurements from the SORCE satellite, both for total irradiance and broken down into spectral regions on timescales of several years. Methods: use SATIRE model compare (TSI) TSI between 2003 2009. Spectral over 200-1630nm is compared SIM instrument 2004 2009 during a period decline moderate activity to recent minimum in 10 nm bands three significant interest: UV integrated 200-300nm, visible 400-691nm IR 972-1630 nm....
Abstract. Observations of stratospheric ozone from multiple instruments now span three decades; combining these into composite datasets allows long-term trends to be estimated. Recently, several composites have been published, but disagree by latitude and altitude, even between built upon the same instrument data. We confirm that main causes differences in decadal trend estimates lie (i) steps time series when source data changes (ii) artificial sub-decadal underlying These artefacts...
We present a revised and extended total spectral solar irradiance (SSI) reconstruction, which includes wavelength-dependent uncertainty estimate, spanning the last three cycles using SATIRE-S model. The SSI reconstruction covers wavelengths between 115 160,000 nm all dates August 1974 October 2009. This represents first full-wavelength to cover without data gaps with an estimate. is compared NRLSSI model SORCE/SOLSTICE ultraviolet (UV) observations. displays similar cycle behaviour for below...
Abstract. This paper features the new atmosphere–ocean–aerosol–chemistry–climate model, SOlar Climate Ozone Links (SOCOL) v4.0, and its validation. The model was built by interactively coupling Max Planck Institute Earth System Model version 1.2 (MPI-ESM1.2) (T63, L47) with chemistry (99 species) size-resolving (40 bins) sulfate aerosol microphysics modules from aerosol–chemistry–climate SOCOL-AERv2. We evaluate performance against reanalysis products observations of atmospheric circulation,...
Abstract. Under climate change driven by increased carbon dioxide (CO2) concentrations, stratospheric ozone will respond to temperature and circulation changes, lead chemistry-climate feedback modulating large-scale atmospheric Earth's energy budget. However, there is a significant model uncertainty since many processes are involved few models have detailed chemistry scheme. This work employs the latest data from Coupled Model Intercomparison Project Phase 6 (CMIP6), investigate response...
Abstract. Solar spectral fluxes (or irradiance) measured by the SOlar Radiation and Climate Experiment (SORCE) show different variability at ultraviolet (UV) wavelengths compared to other irradiance measurements models (e.g. NRL-SSI, SATIRE-S). Some modelling studies have suggested that stratospheric/lower mesospheric O3 changes during solar cycle 23 (1996–2008) can only be reproduced if SORCE are used. We used a 3-D chemical transport model (CTM), forced meteorology from European Centre for...
Abstract. Stratospheric water vapour (SWV) is an important component of the Earth's atmosphere as it affects both radiative balance and chemistry atmosphere. Key processes driving changes in SWV include dehydration air masses transiting cold-point tropopause (CPT) methane oxidation. We use a chemistry–climate model to simulate through 21st century following four canonical representative concentration pathways (RCPs). Furthermore, we quantify contribution that oxidation makes each RCPs....
Abstract The solar cycle (SC) stratospheric ozone response is thought to influence surface weather and climate. To understand the chain of processes ensure climate models adequately represent them, it important detect quantify an accurate SC from observations. Chemistry (CCMs) observations display a range upper stratosphere (1–10 hPa) zonally averaged spatial responses; this recommended data set for comparison remains disputed. Recent data‐merging advancements have led more robust...