Global Ozone Research Articles

The relationship between solar-induced fluorescence and gross primary productivity under different growth conditions: global analysis using satellite and biogeochemical model data

ABSTRACT Solar-induced fluorescence (SIF) has become a milestone for estimating terrestrial gross primary productivity (GPP) at the global scale, and therefore it is important to understand how the relationship between SIF and GPP varies with environmental stresses and canopy structures. Our study investigated the impact of environmental conditions on the relationship between SIF and GPP at the global scale based on Global Ozone Monitoring Instrument 2 (GOME-2) SIF and Max Planck Institute for Biogeochemistry (MPI-BGC) GPP. GOME-2 SIF had strong correlations with gridded GPP data at instantaneous (R 2 = 0.618, p < 0.001) and daily timescales (R 2 = 0.621, p < 0.001) across the globe in eleven major biomes. Strong linear relationships were also consistently found for nine individual biomes at the daily timescale (R 2 = 0.512–0.839, p < 0.001) but were not found for evergreen broadleaf forests (EBF) (R 2 = 0.142, p < 0.001) and closed shrublands (R 2 = 0.395, p < 0.001). Generally, high coefficients of determination (R 2 > 0.8) were mainly distributed in southern Europe, southern and central Africa, northeastern and central China, North America, India and southern Russia, and the slope had a similar spatial distribution as the coefficients of determination. The relationship between SIF and GPP varied with air temperature (T Air), vapour pressure deficit (VPD) and leaf area index (LAI). The slope of the SIF-GPP relationship had a maximal value when the air temperature ranged between approximately 10°C and 20°C, when the linear relationships between SIF and GPP were also the strongest. Our analysis based on the Soil-Canopy Observation of Photochemistry and Energy fluxes (SCOPE) model also indicated that the SIF-GPP relationship was complex and affected by T Air, VPD and LAI. Our study can improve our understanding of the functional relationship between SIF and GPP and the information contained in remotely sensed SIF.

Systematic Orbital Geometry-Dependent Variations in Satellite Solar-Induced Fluorescence (SIF) Retrievals

While solar-induced fluorescence (SIF) shows promise as a remotely-sensed measurement directly related to photosynthesis, interpretation and validation of satellite-based SIF retrievals remains a challenge. SIF is influenced by the fraction of absorbed photosynthetically-active radiation at the canopy level that depends upon illumination geometry as well as the escape of SIF through the canopy that depends upon the viewing geometry. Several approaches to estimate the effects of sun-sensor geometry on satellite-based SIF have been proposed, and some have been implemented, most relying upon satellite reflectance measurements and/or other ancillary data sets. These approaches, designed to ultimately estimate intrinsic or physiological components of SIF related to photosynthesis, have not generally been applied globally to satellite measurements. Here, we examine in detail how SIF and related reflectance-based indices from wide swath polar orbiting satellites in low Earth orbit vary systematically due to the host satellite orbital characteristics. We compare SIF and reflectance-based parameters from the Global Ozone Mapping Experiment 2 (GOME-2) on the MetOp-B platform and from the TROPOspheric Monitoring Instrument (TROPOMI) on the Sentinel 5 Precursor satellite with a focus on high northern latitudes in summer where observations at similar geometries and local times occur. We show that GOME-2 and TROPOMI SIF observations agree nearly to within estimated uncertainties when they are compared at similar observing geometries. We show that the cross-track dependence of SIF normalized by PAR and related reflectance-based indices are highly correlated for dense canopies, but diverge substantially as the vegetation within a field-of-view becomes more sparse. This has implications for approaches that utilize reflectance measurements to help account for SIF geometrical dependences in satellite measurements. To further help interpret the GOME-2 and TROPOMI SIF observations, we simulated cross-track dependences of PAR normalized SIF and reflectance-based indices with the one dimensional Soil-Canopy Observation Photosynthesis and Energy fluxes (SCOPE) canopy radiative transfer model at sun–satellite geometries that occur across the wide swaths of these instruments and examine the geometrical dependencies of the various components (e.g., fraction of absorbed PAR, SIF yield, and escape of SIF from the canopy) of the observed SIF signal. The simulations show that most of the cross-track variations in SIF result from the escape of SIF through the scattering canopy and not the illumination.

Life Cycle Assessment of Ball Bladder Production With and Without Recycled Rubbers

Background: Environmental issues such as global warming and ozone depletion are one of the most controversial concerns of scientists due to their several potential impacts on the earth as a result of long-term emission of greenhouse gases, mainly CH4 and CO2. Evidence of greenhouse gas emissions during rubber production provides important and useful data for Life Cycle Assessment (LCA). The present study aimed to reduce the emission rate of greenhouse gases in the ball bladder production process using natural rubber in combination with recycled rubber. Methods: In this regard, a LCA in SimaPro 8.0.1 software using CML2001 method was conducted on data related to the resources, chemicals, raw materials and energy consumption during ball manufacturing in Tanin Peak Sabalan Factory, Ardabil, Iran. Results: Our findings revealed that the ball bladder with natural rubber had the largest contribution to the ozone layer depletion (39.2%) and global warming (41.1%), while the bladder with both recycled and natural rubbers had an impact of 27.9% and 29.5%, respectively. Conclusion: In conclusion, the ball bladder with both recycled and natural rubbers is less eco-destructive than that the bladder with only natural rubber.

Pre-service biology teachers’ perception of global warming, greenhouse effect and ozone layer depletion in Lagos State University

The study examined the crux about global warming, greenhouse effect and ozone layer depletion among pre-service biology teachers. A survey questionnaire adapted from Kalipit, Yener &amp; Ozkadif (2009); Rye, Ruba &amp; Wiesenmayer (1997) and Boyes, Chambers &amp; Stanisstreet (1995) was administered to 65 pre-service Biology teachers purposively selected from the Department of Science and Technology Education, Lagos State University, Lagos. This was to determine the pre-service biology teachers’ perceptions about global warming, greenhouse effect and ozone layer depletion. Data collected were analyzed using descriptive statistics. Results showed that pre-service Biology teachers had misconceptions that the results of thinning of ozone layer will increase greenhouse effect and the function of ozone layer is to protect the earth against excessive heat. Furthermore, majority of the preservice biology teachers had misconceptions on global warming, ozone layer depletion and greenhouse effect. It is imperative, therefore to proffer solutions to these misconceptions held by the pre-service teachers by ensuring that instructors and instructional materials emphasize the importance of these concepts to life ensuring that students have adequate knowledge about the concepts as well as ways of tackling these challenges.&#x0D; Keyword: Global warming, greenhouse effect, ozone layer depletion, pre-service biology teachers, misconceptions.

Spatial-Temporal Variation Characteristics of Vertical Dust Flux Simulated by WRF-Chem Model with GOCART and AFWA Dust Emission Schemes (Case Study: Central Plateau of Iran)

Dust and sand storms are among the major threats to central Iran. These phenomena pose irreparable risks to natural ecosystems and human societies, including effects on health. In this study, the spatial and temporal pattern of vertical dust flux (VDF) was used to identify dust sources as well as areas with high potential for dust generation. To simulate VDF, two intense dust storms, from 21 February 2015 and 14 February 2018, were selected using synoptic data and Moderate Resolution Imaging Spectroradiometer (MODIS) images. These dust storms were identified as responsible for a reduction of horizontal visibility to less than 1000 m, using remote sensing tools and Ackerman Dust Index. MODIS images show that these two storms covered most of Central Plateau of Iran. The Weather Research and Forecasting model with chemistry (WRF-Chem) was used to simulate the storms, with either the Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) or Air Force Weather Agency (AFWA) scheme to calculate VDF. Modeled vertical dust fluxes in both events indicate that the Arabian deserts in Saudi Arabia and in southwestern Iran can be identified as main sources of the dust in the central Iranian plateau. The other source of dust is the Hirmand Basin, located in the country of Afghanistan and in the southeast of Iran. The results of VDF simulations indicate that central southeast Iran could be the main dust source of internal origin. Additionally, over seasonal wetlands in Iran, the amount of VDF was simulated to be sometimes over 4000 μg/(m2s), an indication that these areas are sensitive to wind erosion in dry conditions and can be a source of dust. The WRF-Chem results were compared with the horizontal visibility measured in synoptic stations in the area. The results showed that the coefficients of determination of GOCART results with the measured horizontal visibility on 21 February 2015 and 14 February 2018 were 0.72 and 0.76, respectively, while the coefficient values from the simulations with AFWA scheme on 21 February 2015 and 14 February 2018 with the measured horizontal visibility were lower, 0.44 and 0.50, respectively. Modern-Era Retrospective analysis for Research and Applications, version 2 (MERRA2) re-analysis data also showed timing of peak dust levels consistent with the GOCART scheme.

Evaluating the impact of blowing-snow sea salt aerosol on springtime BrO and O&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt; in the Arctic

Abstract. We use the GEOS-Chem chemical transport model to examine the influence of bromine release from blowing-snow sea salt aerosol (SSA) on springtime bromine activation and O3 depletion events (ODEs) in the Arctic lower troposphere. We evaluate our simulation against observations of tropospheric BrO vertical column densities (VCDtropo) from the GOME-2 (second Global Ozone Monitoring Experiment) and Ozone Monitoring Instrument (OMI) spaceborne instruments for 3 years (2007–2009), as well as against surface observations of O3. We conduct a simulation with blowing-snow SSA emissions from first-year sea ice (FYI; with a surface snow salinity of 0.1 psu) and multi-year sea ice (MYI; with a surface snow salinity of 0.05 psu), assuming a factor of 5 bromide enrichment of surface snow relative to seawater. This simulation captures the magnitude of observed March–April GOME-2 and OMI VCDtropo to within 17 %, as well as their spatiotemporal variability (r=0.76–0.85). Many of the large-scale bromine explosions are successfully reproduced, with the exception of events in May, which are absent or systematically underpredicted in the model. If we assume a lower salinity on MYI (0.01 psu), some of the bromine explosions events observed over MYI are not captured, suggesting that blowing snow over MYI is an important source of bromine activation. We find that the modeled atmospheric deposition onto snow-covered sea ice becomes highly enriched in bromide, increasing from enrichment factors of ∼5 in September–February to 10–60 in May, consistent with composition observations of freshly fallen snow. We propose that this progressive enrichment in deposition could enable blowing-snow-induced halogen activation to propagate into May and might explain our late-spring underestimate in VCDtropo. We estimate that the atmospheric deposition of SSA could increase snow salinity by up to 0.04 psu between February and April, which could be an important source of salinity for surface snow on MYI as well as FYI covered by deep snowpack. Inclusion of halogen release from blowing-snow SSA in our simulations decreases monthly mean Arctic surface O3 by 4–8 ppbv (15 %–30 %) in March and 8–14 ppbv (30 %–40 %) in April. We reproduce a transport event of depleted O3 Arctic air down to 40∘ N observed at many sub-Arctic surface sites in early April 2007. While our simulation captures 25 %–40 % of the ODEs observed at coastal Arctic surface sites, it underestimates the magnitude of many of these events and entirely misses 60 %–75 % of ODEs. This difficulty in reproducing observed surface ODEs could be related to the coarse horizontal resolution of the model, the known biases in simulating Arctic boundary layer exchange processes, the lack of detailed chlorine chemistry, and/or the fact that we did not include direct halogen activation by snowpack chemistry.

Water vapor satellite products in the European Arctic: An inter-comparison against GNSS data

The European Arctic is a region of high interest for climate change. Water vapor plays a fundamental role in global warming; therefore, high-quality water vapor monitoring is essential for assimilation in forecast simulations. The seven analyzed instruments on-board satellite platforms are: Atmospheric Infrared Sounder (AIRS), Global Ozone Monitoring Instrument 2 (GOME-2), Moderate-Resolution Imaging Spectroradiometer (MODIS), Ozone Monitoring Instrument (OMI), SCanning Imaging Absorption Spectrometer for Atmospheric Carthography (SCIAMACHY) and Polarization and Directionality of the Earth's Reflectances (POLDER). The GNSS data from Ny-Ålesund are matched to satellite observations of IWV in a 30-min temporal window, and 100-km radius. Then, statistics and the distribution of satellite-ground differences under different conditions are studied. The correlation coefficient (R2) with ground-based measurements is about 0.7 for all products except OMI (R2=0.5), and MODIS NIR and POLDER (R2=0.3). OMI shows high bias and variability compared to the rest of products. RMSE values are of the order of 3 mm for all satellites, except OMI (7 mm) and POLDER (5 mm). Bias (MBE) is negligible for AIRS, close to +1.6 mm for GOME-2 and MODIS IR, +0.8 mm for MODIS NIR, +5.9 mm for OMI, −2.7 mm for POLDER and −1.2 mm for SCIAMCHY. All satellite products tend to overestimate small IWV values and underestimate large IWV values. Variability also increases with IWV. An underestimation of the satellite products and an increase on the variability is generally observed for large Solar Zenith Angle (SZA) values. Under cloudy conditions, underestimation and variability are increased. Seasonal behavior is driven by the typical cloud cover (CC), SZA, and IWV values. In summer, it is typical to find conditions with large IWV, small SZA and large CC values. Therefore, in summer months satellite products are more biased (either positively or negatively) and with more variability, but in relative terms they are less biased and exhibit less variability.

The potential impacts of a sulfur- and halogen-rich supereruption such as Los Chocoyos on the atmosphere and climate

Abstract. The supereruption of Los Chocoyos (14.6∘ N, 91.2∘ W) in Guatemala ∼84 kyr ago was one of the largest volcanic events of the past 100 000 years. Recent petrologic data show that the eruption released very large amounts of climate-relevant sulfur and ozone-destroying chlorine and bromine gases (523±94 Mt sulfur, 1200±156 Mt chlorine, and 2±0.46 Mt bromine). Using the Earth system model (ESM) of the Community Earth System Model version 2 (CESM2) coupled with the Whole Atmosphere Community Climate Model version 6 (WACCM6), we simulated the impacts of the sulfur- and halogen-rich Los Chocoyos eruption on the preindustrial Earth system. Our simulations show that elevated sulfate burden and aerosol optical depth (AOD) persists for 5 years in the model, while the volcanic halogens stay elevated for nearly 15 years. As a consequence, the eruption leads to a collapse of the ozone layer with global mean column ozone values dropping to 50 DU (80 % decrease) and leading to a 550 % increase in surface UV over the first 5 years, with potential impacts on the biosphere. The volcanic eruption shows an asymmetric-hemispheric response with enhanced aerosol, ozone, UV, and climate signals over the Northern Hemisphere. Surface climate is impacted globally due to peak AOD of &gt;6, which leads to a maximum surface cooling of &gt;6 K, precipitation and terrestrial net primary production decrease of &gt;25 %, and sea ice area increases of 40 % in the first 3 years. Locally, a wetting (&gt;100 %) and strong increase in net primary production (NPP) (&gt;700 %) over northern Africa is simulated in the first 5 years and related to a southward shift of the Intertropical Convergence Zone (ITCZ) to the southern tropics. The ocean responds with pronounced El Niño conditions in the first 3 years that shift to the southern tropics and are coherent with the ITCZ change. Recovery to pre-eruption ozone levels and climate takes 15 years and 30 years, respectively. The long-lasting surface cooling is sustained by an immediate increase in the Arctic sea ice area, followed by a decrease in poleward ocean heat transport at 60∘ N which lasts up to 20 years. In contrast, when simulating Los Chocoyos conventionally by including sulfur and neglecting halogens, we simulate a larger sulfate burden and AOD, more pronounced surface climate changes, and an increase in column ozone. By comparing our aerosol chemistry ESM results to other supereruption simulations with aerosol climate models, we find a higher surface climate impact per injected sulfur amount than previous studies for our different sets of model experiments, since the CESM2(WACCM6) creates smaller aerosols with a longer lifetime, partly due to the interactive aerosol chemistry. As the model uncertainties for the climate response to supereruptions are very large, observational evidence from paleo archives and a coordinated model intercomparison would help to improve our understanding of the climate and environment response.

The discovery of the Antarctic ozone hole

To celebrate its 150 anniversary, Nature collected 10 extraordinary papers published on Nature in November, 2019. One of the papers is on the discovery of the Antarctic ozone hole, which was published by three British scientists, Joe C. Farman, Brian G. Gardiner, and Jonathan D. Shanklin, in 1985. They first showed observational evidence that Antarctic stratospheric ozone experienced drastic decrease in the early 1980s, by contrasting to the relative steady state in the 1970s. They also suggested that the ozone hole is due to human-made chlorofluorocarbons (CFCs). Nature invited Susan Solomon, who made outstanding contributions to our understanding of the ozone hole, to comment on the paper. She pointed out that “The unexpected discovery of a hole in the atmospheric ozone layer over the Antarctic revolutionized science—and helped to establish one of the most successful global environmental policies of the twentieth century.” The observational evidence by Farman et al. greatly confirmed earlier theoretical works by P. Cruzen, M. Molina, and F. Rowland who first emphasized in the 1970s that anthropogenic emissions of nitrogen oxides and CFCs would damage the ozone layer. Their observational confirmation led to the winning of the Nobel Prize in Chemistry by Cruzen, Molina, and Rowland in 1995. The discovery of the ozone hole also led to great international actions in reducing CFCs emissions and protecting the ozone layer, which is crucially important for screening solar ultraviolet radiation for surface life. A series of conventions has been organized by the United Nations, and the most successful one is the 1987 Montreal Protocol on Substances that Deplete the Ozone Layer. The Montreal Protocol and the succeeding amendments, adjustments, and decisions were subsequently negotiated to control the consumption and production of anthropogenic emissions of ozone-depleting substances (ODSs) and some hydrofluorocarbons (HFCs). Since then, ODSs emissions have been largely reduced and showed rapid decrease since the early 1990s. The global ozone layer and the ozone hole over Antarctic all have showed gradual increasing since the late 1990s. According to predictions of climate-chemistry models, the global total column ozone will return to its 1980 values by 2045 when ODSs decline to very low levels, and the Antarctic ozone hole will recover by 2060. The gradual recovery of the ozone hole, due to reducing anthropogenic emissions, from severe depletion also due to human emissions, is considered a successful story that human can protect their environment through self-efforts. It provides us with the confidence that we are able to reduce greenhouse gas emissions and to solve the problem of global greenhouse warming. In the present paper, we will first introduce the discovery of the Antarctic ozone hole by Farman et al. Then, we introduce the chemical mechanisms of the Chapman and the catalytic reactions that result in the formation of the ozone layer, and how anthropogenic perturbations caused the Antarctic ozone hole. We shall also introduce the actions that was taken by international communities to protect the ozone layer. In the final section, we point out the important implications of the discovery of the ozone hole.

CO2 Concentration, A Critical Factor Influencing the Relationship between Solar-induced Chlorophyll Fluorescence and Gross Primary Productivity

The uncertainty of carbon fluxes of the terrestrial ecosystem is the highest among all flux components, calling for more accurate and efficient means to monitor land sinks. Gross primary productivity (GPP) is a key index to estimate the terrestrial ecosystem carbon flux, which describes the total amount of organic carbon fixed by green plants through photosynthesis. In recent years, the solar-induced chlorophyll fluorescence (SIF), which is a probe for vegetation photosynthesis and can quickly reflect the state of vegetation growth, emerges as a novel and promising proxy to estimate GPP. The launch of Orbiting Carbon Observatory 2 (OCO-2) further makes it possible to estimate GPP at a finer spatial resolution compared with Greenhouse Gases Observing Satellite (GOSAT), Global Ozone Monitoring Experiment-2 (GOME-2) and SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY). However, whether the relationship between GPP and SIF is linear or non-linear has always been controversial. In this research, we proposed a new model to estimate GPP using SIF and the atmospheric CO2 concentration from OCO-2 as critical driven factors simultaneously (SIF-CO2-GPP model). Evidences from all sites show that the introduction of the atmospheric CO2 concentration improves accuracies of estimated GPP. Compared with the SIF-CO2-GPP linear model, we found the SIF-GPP model overestimated GPP in summer and autumn but underestimated it in spring and winter. A series of simulation experiments based on SCOPE (Soil-Canopy Observation of Photosynthesis and Energy) was carried out to figure out the possible mechanism of improved estimates of GPP due to the introduction of atmospheric CO2 concentrations. These experiments also demonstrate that there could be a non-linear relationship between SIF and GPP at half an hour timescale. Moreover, such relationships vary with CO2 concentration. As OCO-2 is capable of providing SIF and XCO2 products with identical spatial and temporal scales, the SIF-CO2-GPP linear model would be implemented conveniently to monitor GPP using remotely sensed data. With the help of OCO-3 and its successors, the proposed SIF-CO2-GPP linear model would play a significant role in monitoring GPP accurately in large geographical extents.

Comparative life-cycle assessment of a mass timber building and concrete alternative

The US housing construction market consumes vast amounts of resources, with most structural elements derived from wood, a renewable and sustainable resource. The same cannot be said for all nonresidential or high-rise buildings, which are primarily made of concrete and steel. As part of continuous environmental improvement processes, building life-cycle assessment (LCA) is a useful tool to compare the environmental footprint of building structures. This study is a comparative LCA of an 8360-m2, 12-story mixed-us apartment/office building designed for Portland, OR, and constructed from mainly mass timber. The designed mass timber building had a relatively lightweight structural frame that used 1782 m3 of cross-laminated timber (CLT) and 557 m3 of glue-laminated timber (glulam) and associated materials, which replaced approximately 58% of concrete and 72% of rebar that would have been use in a conventional building. Compared with a similar concrete building, the mass timber building had 18%, 1% and 47% reduction in the impact categories of global warming, ozone depletion, and eutrophication, respectively, for the A1-A5 building LCA. The use of CLT and glulam materials substantially decreased the carbon footprint of the building, although it consumed more primary energy compared with a similar concrete building. The impacts for the mass timber building were affected by large amounts of gypsum board, which accounted for 16% of the total building mass. Both lowering the amount of gypsum and keeping the mass timber production close to the construction site could lower the overall environmental footprint of the mass timber building.

Monte Carlo analyses of the uncertainties in the predictions from global tropospheric ozone models: Tropospheric burdens and seasonal cycles

Abstract Because ozone is a highly reactive trace gas, estimates of its contribution to climate forcing must rely on global chemistry-transport models. These models employ many uncertain input parameters representing the sources and sinks for tropospheric ozone. Ten thousand quasi-randomly Monte Carlo sampled model runs employing a zonally-averaged global ozone model were completed and the output uncertainties were estimated in the burdens and turnovers of methane, carbon monoxide and ozone, together with the uncertainties in the ozone seasonal cycles. Multiple regression was then used to attribute the uncertainty in each output metric to each of the 183 uncertain input parameters which represented emission source sectors, chemical and photochemical rate coefficients, dry deposition velocities and biases in temperature and water vapour concentrations. We have tentatively identified sixteen chemical and photochemical rate coefficients, eight emission source sectors, ozone dry deposition and biases in temperature and water vapour as contributing most to the uncertainties in our chosen output metrics. Ten out of the sixteen chemical processes turned out to be the most important processes in the fast, photochemical balance of the troposphere. Emissions from NOx, methane, carbon monoxide and isoprene had the potential to contribute in a major way to model output uncertainties. There are, however, many limitations to our study, not the least being our use of a two-dimensional (altitude-latitude) ozone model. We have not been able to resolve the apparent conflicts between our model and the observations of ozone seasonal cycles and these must await a more rigorous treatment of tropospheric ozone sources and sinks before they can be resolved.

Assessing the benefit of satellite-based Solar-Induced Chlorophyll Fluorescence in crop yield prediction

Large-scale crop yield prediction is critical for early warning of food insecurity, agricultural supply chain management, and economic market. Satellite-based Solar-Induced Chlorophyll Fluorescence (SIF) products have revealed hot spots of photosynthesis over global croplands, such as in the U.S. Midwest. However, to what extent these satellite-based SIF products can enhance the performance of crop yield prediction when benchmarking against other existing satellite data remains unclear. Here we assessed the benefits of using three satellite-based SIF products in yield prediction for maize and soybean in the U.S. Midwest: gap-filled SIF from Orbiting Carbon Observatory 2 (OCO-2), new SIF retrievals from the TROPOspheric Monitoring Instrument (TROPOMI), and the coarse-resolution SIF retrievals from the Global Ozone Monitoring Experiment-2 (GOME-2). The yield prediction performances of using SIF data were benchmarked with those using satellite-based vegetation indices (VIs), including normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), and near-infrared reflectance of vegetation (NIRv), and land surface temperature (LST). Five machine-learning algorithms were used to build yield prediction models with both remote-sensing-only and climate-remote-sensing-combined variables. We found that high-resolution SIF products from OCO-2 and TROPOMI outperformed coarse-resolution GOME-2 SIF product in crop yield prediction. Using high-resolution SIF products gave the best forward predictions for both maize and soybean yields in 2018, indicating the great potential of using satellite-based high-resolution SIF products for crop yield prediction. However, using currently available high-resolution SIF products did not guarantee consistently better yield prediction performances than using other satellite-based remote sensing variables in all the evaluated cases. The relative performances of using different remote sensing variables in yield prediction depended on crop types (maize or soybean), out-of-sample testing methods (five-fold-cross-validation or forward), and record length of training data. We also found that using NIRv could generally lead to better yield prediction performance than using NDVI, EVI, or LST, and using NIRv could achieve similar or even better yield prediction performance than using OCO-2 or TROPOMI SIF products. We concluded that satellite-based SIF products could be beneficial in crop yield prediction with more high-resolution and good-quality SIF products accumulated in the future.

Life cycle assessment of alternative building floor rehabilitation systems

The aim of this study is to quantify and compare the environmental impact from cradle-to-gate of different systems for building floor rehabilitation.The Life Cycle Assessment (LCA) method was used for the evaluation of the potential environmental impact of the production of each floor system in eight categories and a monetisation method was used for the weighting of the results and for their expression into one single indicator. Five functionally equivalent (from a structural standpoint) systems were assessed, including: (i) traditional solutions, such as timber floors and reinforced concrete (RC) slabs; (ii) less conventional solutions, such as beam-and-block and steel–concrete composite slab systems; and (iii) an innovative glass fibre reinforced polymer (GFRP) sandwich panel system. The environmental impacts of these systems are compared in this paper for the first time.It was found out that timber is the most environmentally friendly solution, since it presents the lowest total values in all environmental impact categories (under 1% of the impact of the solution with highest impact in each category, RC or GFRP), except for primary renewable energy consumption, for which the RC solution presents the least consumption. On the other hand, it was found out that: the steel–concrete composite floor is the least environmentally friendly solution in abiotic resource depletion; the RC solution is the least performing option in terms of global warming potential and ozone depletion potential; and the GFRP system presents the worst behaviour in five environmental impact categories – non-renewable energy consumption, photochemical ozone formation potential, acidification potential, eutrophication potential and Eco-costs. However, if the most important inefficiencies identified during the production of the latter floor system are at least partly amended, its impacts would be substantially reduced, particularly regarding the Eco-costs indicator, which considers four environmental categories at once – in that case, the RC solution would become the worst solution and GFRP sandwich panels would have an aggregated result of 80% of the RC. The final part of the paper presents a qualitative assessment of the gate-to-grave performance of the different solutions.

Surface Propensity of Aqueous Atmospheric Bromine at the Liquid-Gas Interface.

Multiphase reactions of halide ions in aqueous solutions exposed to the atmosphere initiate the formation of molecular halogen compounds in the gas phase. Their photolysis leads to halogen atoms, which are catalytic sinks for ozone, making these processes relevant for the regional and global tropospheric ozone budget. The affinity of halide ions in aqueous solution for the liquid-gas interface, which may influence their reactivity with gaseous species, has been debated. Our study focuses on the surface properties of the bromide ion and its oxidation products. In situ X-ray photoelectron spectroscopy carried out on a liquid jet combined with classical and first-principles molecular dynamics calculations was used to investigate the interfacial depth profile of bromide, hypobromite, hypobromous acid, and bromate. The simulated core electron binding energies support the experimentally observed values, which follow a correlation with bromine oxidation state for the anion series. Bromide ions are homogeneously distributed in the solution. Hypobromous acid, a key species in the multiphase cycling of bromine, is the only species showing surface propensity, which suggests a more important role of the interface in multiphase bromine chemistry than thought so far.

Losing a Radiant Star—Dr. Edward C. De Fabo (1937–2019)

On December 24, 2019, the pigment, melanoma, and photobiology research communities lost a treasure. Dr. Edward De Fabo passed away peacefully after a valiant 5-year battle against advanced colon cancer. He was 82. He is survived by his wife of 33 years, Dr. Frances Noonan, who had also been his scientific partner. Together, they were a remarkable team, seeking and finding answers to critical scientific questions that had plagued researchers for decades.

Comparison of GTO-ECV and adjusted MERRA-2 total ozone columns from the last 2 decades and assessment of interannual variability

Abstract. In this study we compare the satellite-based Global Ozone Monitoring Experiment (GOME)-type Total Ozone Essential Climate Variable (GTO-ECV) record, generated as part of the European Space Agency's Climate Change Initiative (ESA-CCI) ozone project, with the adjusted total ozone product from the Modern Era Retrospective Analysis for Research and Applications version 2 (adjusted MERRA-2) reanalysis, produced at the National Aeronautics and Space Administration (NASA) Global Modeling and Assimilation Office (GMAO). Total ozone columns and associated standard deviations show a very good agreement in terms of both spatial and temporal patterns during their 23-year overlap period from July 1995 to December 2018. The mean difference between adjusted MERRA-2 and GTO-ECV 5∘×5∘ monthly mean total ozone columns is -0.9±1.5 %. A small discontinuity in the deviations is detected in October 2004, when data from the Ozone Monitoring Instrument (OMI) were ingested in the GTO-ECV and adjusted MERRA-2 data records. This induces a small overall negative drift in the differences for almost all latitude bands, which, however, does not exceed 1 % per decade. The mean difference for the period prior to October 2004 is -0.5±1.7 %, whereas the difference is -1.0±1.1 % for the period from October 2004 to December 2018. The variability in the differences is considerably reduced in the period after 2004 due to a significant increase in data coverage and sampling. In the tropical region, the differences indicate a slight zonal variability with negative deviations over the Atlantic, Africa, and the Indian Ocean and positive deviations over the Pacific. Ozone anomalies and the distribution of their statistical moments indicate a very high correlation among both data records as to the temporal and spatial structures. Furthermore, we evaluate the consistency of the data sets by means of an empirical orthogonal function (EOF) analysis. The interannual variability is assessed in the tropics, and both GTO-ECV and adjusted MERRA-2 exhibit a remarkable agreement with respect to the derived patterns. The first four EOFs can be attributed to different modes of interannual climate variability, and correlations with the Quasi-Biennial Oscillation (QBO), the El Niño–Southern Oscillation (ENSO) signal, and the solar cycle were found.

Revisión del estado del arte de sistemas DX-SAHP para la obtención de agua caliente sanitaria

El objetivo del presente artículo es revisar de forma detallada las distintas investigaciones realizadas con sistemas de bombas de calor de expansión directa asistidas por energía solar (DX-SAHP) utilizadas para el calentamiento de agua en los últimos años. El creciente consumo energético, el uso de refrigerantes que debilitan la capa de ozono, la emisión de gases de efecto invernadero a la atmósfera y los efectos en el calentamiento global, son los principales problemas que presentan los sistemas convencionales de calentamiento de agua. El uso de hidrocarburos como refrigerantes representa una reducción en la contaminación, además de ser una de las mejores opciones para reemplazar a los clorofluorocarbonos e hidroclorofluorocarbonos por sus valores de potencial de calentamiento global y potencial de destrucción de la capa de ozono cercanos a 0. Un sistema DX-SAHP aprovecha la energía solar térmica directamente, empleando un colector solar de placa plana sin cubierta. Esos sistemas proporcionan agua caliente sanitaria a más de 50 °C, calentando volúmenes de agua de hasta 200 litros, alcanzando valores de COP superiores a 4. La energía solar y el uso de refrigerantes alternativos de bajo impacto ambiental son propuestos para alcanzar este propósito.

An intercomparison of tropospheric ozone reanalysis products from CAMS, CAMS interim, TCR-1, and TCR-2

Abstract. Global tropospheric ozone reanalyses constructed using different state-of-the-art satellite data assimilation systems, prepared as part of the Copernicus Atmosphere Monitoring Service (CAMS-iRean and CAMS-Rean) as well as two fully independent reanalyses (TCR-1 and TCR-2, Tropospheric Chemistry Reanalysis), have been intercompared and evaluated for the past decade. The updated reanalyses (CAMS-Rean and TCR-2) generally show substantially improved agreements with independent ground and ozone-sonde observations over their predecessor versions (CAMS-iRean and TCR-1) for diurnal, synoptical, seasonal, and interannual variabilities. For instance, for the Northern Hemisphere (NH) mid-latitudes the tropospheric ozone columns (surface to 300 hPa) from the updated reanalyses show mean biases to within 0.8 DU (Dobson units, 3 % relative to the observed column) with respect to the ozone-sonde observations. The improved performance can likely be attributed to a mixture of various upgrades, such as revisions in the chemical data assimilation, including the assimilated measurements, and the forecast model performance. The updated chemical reanalyses agree well with each other for most cases, which highlights the usefulness of the current chemical reanalyses in a variety of studies. Meanwhile, significant temporal changes in the reanalysis quality in all the systems can be attributed to discontinuities in the observing systems. To improve the temporal consistency, a careful assessment of changes in the assimilation configuration, such as a detailed assessment of biases between various retrieval products, is needed. Our comparison suggests that improving the observational constraints, including the continued development of satellite observing systems, together with the optimization of model parameterizations such as deposition and chemical reactions, will lead to increasingly consistent long-term reanalyses in the future.

Rapid Increases in Warm-Season Surface Ozone and Resulting Health Impact in China Since 2013

China’s nationwide ozone monitoring network initiated in 2013 has observed severe surface ozone pollution. This network, combined with the recent Tropospheric Ozone Assessment Report (TOAR) data set, offers a more comprehensive view on global surface ozone distribution and trends. Here, we report quantitative estimates of the warm-season (April–September) surface ozone trends and resulting health impacts at Chinese cities in 2013–2019. Both the parametric and nonparametric linear trends for 12 ozone metrics relevant to human health and vegetation exposure are derived. We find that all ozone metrics averaged from Chinese urban sites have increased significantly since 2013. The warm-season daily maximum 8-h average (MDA8) ozone levels increased by 2.4 ppb (5.0%) year–¹, with over 90% of the sites showing positive trends and 30% with trends larger than 3.0 ppb year–¹. These rates are among the fastest trends, even faster in some Chinese cities, compared with the urban ozone trends in any other region worldwide reported in TOAR. Ozone metrics reflecting the cumulative exposure effect on human health and vegetation such as SOMO35 and AOT40 have increased at even faster rates (>10% year–¹). We estimate that the total premature respiratory mortalities attributable to ambient MDA8 ozone exposure in 69 Chinese cities are 64,370 in 2019, which has increased by 60% compared to 2013 levels and requires urgent attention.