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Atmospheric carbon dioxide enrichment (eCO 2 ) can enhance plant carbon uptake and growth 1-5 , thereby providing an important negative feedback to climate change by slowing the rate of increase of the atmospheric CO 2 concentration 6 . Although evidence gathered from young aggrading forests has generally indicated a strong CO 2 fertilization effect on biomass growth 3-5 , it is unclear whether mature forests respond to eCO 2 in a similar way. In mature trees and forest stands 7-10 , photosynthetic uptake has been found to increase under eCO 2 without any apparent accompanying growth response, leaving the fate of additional carbon fixed under eCO 2 unclear 4,5,7-11 . Here using data from the first ecosystem-scale Free-Air CO 2 Enrichment (FACE) experiment in a mature forest, we constructed a comprehensive ecosystem carbon budget to track the fate of carbon as the forest responded to four years of eCO 2 exposure. We show that, although the eCO 2 treatment of +150 parts per million (+38 per cent) above ambient levels induced a 12 per cent (+247 grams of carbon per square metre per year) increase in carbon uptake through gross primary production, this additional carbon uptake did not lead to increased carbon sequestration at the ecosystem level. Instead, the majority of the extra carbon was emitted back into the atmosphere via several respiratory fluxes, with increased soil respiration alone accounting for half of the total uptake surplus. Our results call into question the predominant thinking that the capacity of forests to act as carbon sinks will be generally enhanced under eCO 2 , and challenge the efficacy of climate mitigation strategies that rely on ubiquitous CO 2 fertilization as a driver of increased carbon sinks in global forests.

In the last decades, the increase in global industrialization and the consequent technological progress have damaged the quality of the environment. As a consequence, the high levels of hazardous compounds such as metals and gases released in the atmosphere and water, have raised several concerns about the health of living organisms. Today, many analytical techniques are available with the aim to detect pollutant chemical species. However, a lot of them are not affordable due to the expensive instrumentations, time-consuming processes and high reagents volumes. Last but not least, their use is exclusive to trained operators. Contrarily, colorimetric sensing devices, including paper-based devices, are easy to use, providing results in a short time, without particular specializations to interpret the results. In addition, the colorimetric response is suitable for fast detection, especially in resource-limited environments or underdeveloped countries. Among different chemical species, transition and heavy metals such as iron Fe(II) and copper Cu(II) as well as volatile compounds, such as ammonia (NH3) and acetaldehyde (C2H4O) are widespread mainly in industrialized geographical areas. In this work, we developed a colorimetric paper-based analytical device (PAD) to detect different contaminants, including Fe2+ and Cu2+ ions in water, and NH3 and C2H4O in air at low concentrations. This study is a "proof of concept" of a new paper sensor in which the intensity of the colorimetric response is proportional to the concentration of a detected pollutant species. The sensor model could be further implemented in other technologies, such as drones, individual protection devices or wearable apparatus to monitor the exposure to toxic species in both indoor and outdoor environments. [ABSTRACT FROM AUTHOR]

The article assesses the usefulness of synthetic vortex insertion prior to the extratropical transition of hurricanes. Significant improvements in the wind and precipitation patterns within the storm at landfall were observed in the atmospheric model with vortex insertion employed in the initial conditions. The numerical hindcasts employing the technique resolved a particular forecast dilemma involving interaction of Hurricane Michael with a preexisting area of low pressure to its north. Operational forecast models at the time had incorrectly developed the northern low at the expense of the hurricane, while the opposite occurred in reality and in the numerical simulations run in hindcast mode.

The article offers news briefs related to climatology. A cold tongue which is a narrow band of cool sea surface temperature (SST) is one of the salient features in the equatorial Pacific Ocean. Two of the factors that contributed to the weather-forecasting errors increase in time are the amplification uncertainties of nonlinearities in the initial state of the atmosphere and the model deficiencies leading the model to predict the wrong rate of change for even the most certain initial conditions. INSETS: DUDE, WE'RE, LIKE, PROTESTING;PLEASED TO ZAP YOU.

This paper is intended to summarize the research conducted during the first 2 years of the Dragon 5 project 59,332 (geophysical and atmospheric retrieval from Synthetic Aperture Radar (SAR) data stacks over natural scenarios). Monitoring atmospheric phenomena, encompassing both tropospheric and ionospheric conditions, holds pivotal significance for various scientific and practical applications. In this paper, we present an exploration of advanced techniques for estimating tropospheric and ionospheric phase screens using stacks of Synthetic Aperture Radar (SAR) images. Our study delves into the current state-of-the-art in atmospheric monitoring with a focus on spaceborne SAR systems, shedding light on their evolving capabilities. For tropospheric phase screen estimation, we propose a novel approach that jointly estimates the tropospheric component from all the images. We discuss the methodology in detail, highlighting its ability to recover accurate tropospheric maps. Through a series of quantitative case studies using real Sentinel-1 satellite data, we demonstrate the effectiveness of our technique in capturing tropospheric variability over different geographical regions. Concurrently, we delve into the estimation of ionospheric phase screens utilizing SAR image stacks. The intricacies of ionospheric disturbances pose unique challenges, necessitating specialized techniques. We dissect our approach, showcasing its capacity to mitigate ionospheric noise and recover precise phase information. Real data from the Sentinel-1 satellite are employed to showcase the efficacy of our method, unraveling ionospheric perturbations with improved accuracy. The integration of our techniques, though presented separately for clarity, collectively contributes to a comprehensive framework for atmospheric monitoring. Our findings emphasize the potential of SAR-based approaches in advancing our knowledge of atmospheric processes, thus fostering advancements in weather prediction, geophysics, and environmental management. [ABSTRACT FROM AUTHOR]

This paper reviews how excessive lighting in historical sites can negatively affect the enjoyment of social gatherings. Because light pollution has the potential to affect socialization negatively, we need the appropriate tools to handle these effects. As part of this research, three techniques were used to analyze these effects: a bibliographical examination of relevant concepts, field measurements of illumination levels at historical sites in Cairo, Egypt, as well as questionnaires sent out to users around the world to determine what influences their perceptions of historical sites at night. Based on the results of a systematic review, we developed the concept of toolkits for creating a lively ambiance for evening events. Furthermore, based on the spatial measurements made in the case study, it was determined that the challenge of visual pollution hinders creating a vibrant atmosphere at historical sites. An online survey that investigated the factors influencing the enjoyment of historical sites at night around the world found that positioning the lighting fixtures and illumination is one of the most critical factors. The results of the current study confirm that the urban form of the context provides a pleasant visual and perceptual experience at night as well. The findings of this study have led to three design considerations that can help urban planners and designers when it comes to implementing lighting in public spaces. As a result of these considerations, the historical site in the case study, Al-Hussein Square, Cairo, presents a livelier ambiance at night; hence they can be used by urban designers to enhance the ambiance in similar settings to the present case study. This toolkit provides valuable insights into how local authorities and citizens can work together to reduce lighting pollution by examining the causes of the pollution. [ABSTRACT FROM AUTHOR]

This paper is concerned with exploring legal atmospheres during colonial expansionism and the early period of confederation of British Columbia. By describing the theatrical and performative aspects of legal colonialism, the archival documents from this time represent interesting, yet oft-overlooked, significances that attention to sensory and affective experiences captures. Examining "affective atmospheres" disclosed in such colonial settings reveals ways that the colonial regime promulgated its influence in non-rational, non-legal manners. As well, drawing out the material conditions of topography shows how the environment acts more than just a backdrop for the staging of legal expansionism, as it acts also as a constitutive force in the development of colonial legal arrangements. At the same time, the colonial regime was forgetful of these same contextual, topographical, and atmospheric origins of law insofar as it promulgated myths of the universality, objectivity, and superiority of English law. [ABSTRACT FROM AUTHOR]

In the Earth's atmosphere, greenhouse gases (GHGs) and reactive trace gases are essential components of chemistry–climate interactions. These trace gases are emitted from both natural and anthropogenic sources over terrestrial and marine regions. Air–sea exchange is the dominant process controlling the distribution of several important trace gases over remote marine regions. Although the ocean–atmosphere interface covers ~70% of the Earth's surface, the quantitative air–sea exchange of reactive trace gases is estimated over the limited oceanic regions. The production and air–sea exchange of trace gases are controlled by physical conditions at both sides of the interface and ocean biogeochemistry. The northern Indian Ocean (NIO) experiences strong seasonal monsoon winds and intense tropical cyclones. Consisting of the Arabian Sea and the Bay of Bengal, it is one of the most biologically productive regimes of the world ocean and home to the intense oxygen minimum zone (OMZ) of the Arabian Sea with dissolved oxygen concentrations. Thus, the NIO offers a unique system to investigate the air–sea exchange processes of reactive trace gases. So far, most of the studies of air–sea exchange of trace gases is focused on the Atlantic and Pacific Oceans, while studies over the northern Indian Ocean are very limited and reported mainly for CH4, CO2 and N2O. Although progress has been made in recent years, studies of air–sea exchange of reactive trace gases such as non-methane hydrocarbon (NMHCs), oxygen-, sulfur- and halogen-containing hydrocarbons remain scarce. This paper addresses the current understanding of air–sea exchange processes and fluxes of reactive trace gases, including NMHCs, dimethyl sulfide (DMS), oxygenated volatile organic compounds (OVOCs), halocarbons, carbon monoxide (CO) and ozone (O3) in the northern Indian Ocean. This review summarizes the studies on the air–sea exchange of trace gases over the northern Indian Ocean and common parametrization approaches used to estimate the air–sea flux of gases. Flux range for ethene (3–10.35 µmol m–2 d–1), isoprene (0.215–0.172 µmol m–2 d–1), acetaldehyde (–6.75–11.35 µmol m–2 d–1), acetone (–9–9 µmol m–2 d–1), DMS (0.03–41.4 µmol m–2 d–1) and CO (1.4–5.4 µmol m–2 d–1) over the NIO were summarized from various in-situ and modelling studies. The paper addresses the importance of the northern Indian Ocean apropos the production and exchange of reactive trace gases, the knowledge gaps and the future scientific scope. Additionally, it emphasizes the need for a multidisciplinary study of oceanic reactive trace gas cycling and its impact on regional atmospheric chemistry over the northern Indian Ocean. [ABSTRACT FROM AUTHOR]

A new one‐dimensional variational (1D‐Var) retrieval method for ionospheric GNSS radio occultation (GNSS‐RO) measurements is described. The forward model implicit in the retrieval calculates the bending angles produced by a one‐dimensional ionospheric electron density profile, modeled with multiple "Vary‐Chap" layers. It is demonstrated that gradient based minimization techniques can be applied to this retrieval problem. The use of ionospheric bending angles is discussed. This approach circumvents the need for Differential Code Bias (DCB) estimates when using the measurements. This new, general retrieval method is applicable to both standard GNSS‐RO retrieval problems, and the truncated geometry of EUMETSAT's Metop Second Generation (Metop‐SG), which will provide GNSS‐RO measurements up to about 600 km above the surface. The climatological a priori information used in the 1D‐Var is effectively a starting point for the 1D‐Var minimization, rather than a strong constraint on the final solution. In this paper the approach has been tested with 143 COSMIC‐1 measurements. We find that the method converges in 135 of the cases, but around 25 of those have high "cost at convergence" values. In the companion paper (Elvidge et al., 2023), a full statistical analysis of the method, using over 10,000 COSMIC‐2 measurements, has been made. Plain Language Summary: This paper presents a new way of estimating the density of electrons in the ionosphere—the part of the Earth's atmosphere in which atoms are ionized by radiation from the Sun. Radio signals sent between GNSS navigational satellites and receivers in a low orbit around the Earth are delayed, and their paths are bent, by the presence of electrons in the ionosphere. Previous attempts to use these observations to estimate the electron density have been based on the delay of the signals. The new approach outlined in this paper uses the bending incurred by the radio waves instead. Such "bending angles" have been used to infer some properties of the lower atmosphere for many years, and are widely available. We demonstrate that by extending these measurements to greater heights, they can provide useful information about the ionosphere as well. Key Points: A new method of deriving ionospheric electron densities, using the difference between bending angles at two different frequenciesIt is based on a 1D variational retrieval, the solution of which is the best fit to the a priori background and the observationsThe forward model assumes the ionosphere to consist of several idealized "Vary‐Chap" electron density layers [ABSTRACT FROM AUTHOR]

In the problem of gliding flight, i.e., aircraft longitudinal movement with its engines switched off, the aircraft was traditionally assumed to be an absolutely rigid body, the Earth was not rotating and had a plane surface, and the atmosphere was quiet. Further, the attack angle and the air density were assumed constant. The aim of this paper is to discuss the applicability limits of these assumptions. [ABSTRACT FROM AUTHOR]

The article presents a response to a comment on an article about a parametrization of solar energy disposition in the climate system. It was pointed out that the description of the treatment of albedo processes in the University of Victoria model is incorrect. It is agreed that the University of Victoria model has a representation of the ice-albedo feedback through the planetary albedo change. The solar energy disposition is poorly simulated and this aspect is usually neglected in model evaluations.

Due to the complexity of the multiple scattering problem for shortwave radiative transfer in Earth's atmosphere, operational physical retrieval algorithms commonly use a plane parallel Radiative Transfer Model (RTM). This so-called One-Dimensional (1-D) assumption allows practical retrieval algorithms to be implemented. In order to understand the impacts of this assumption for low altitude, unresolved clouds observed by OCO-2, the Three-Dimensional (3-D) radiative transfer model SHDOM is used to generate synthetic observations which are then processed by the operational retrieval algorithm based on a 1-D RTM. Simulations are performed over three realistic surface spectral albedos, corresponding to snow, vegetation, and bare soil. The results show that the existing cloud screening algorithm has difficulty identifying sub-Field of View (FOV), unresolved clouds that fill less than half of the FOV. The unresolved clouds introduce a bias in the retrieved CO2 concentration, as quantified by the dry air mole fraction (XCO2). The biases are relatively small (less than 1 ppm) when the albedo at 2.1 µm is high, which is common over bare land surfaces. For cases with low 2.1 µm albedo, such as snow, the bias becomes much larger, up to 5 ppm. These results indicate that the XXCO2 retrieval appears robust to 3-D scattering effects from unresolved low level clouds when the short wave infrared surface albedo is large, but for darker surfaces these clouds can introduce significant biases. [ABSTRACT FROM AUTHOR]

This paper describes an attempt to use data obtained from sodar (sound detection and ranging) for short-term forecasting of PM 10 concentration levels in Krakow. Krakow is one of the most polluted cities in central Europe (CE) in terms of PM 10 concentration. This is due to the high municipal emissions. Thanks to intensive corrective actions taken by the city authorities, these are being effectively eliminated, but the unfavourable topographic location of the city limits natural ventilation. The article describes all these conditions, focusing on presenting the method of short-term correction of air quality for the time needed to take quick corrective actions by the city authorities in the event of anticipated exceedances of the permissible values. Based on several years of measurements of the physical properties of the atmosphere with sodar, the authors of the paper suggest that sodar data could be considered for operational use to generate short-term predictions. The proposed method is based on the use of the spectrum, i.e. the set of amplitudes of signals returning to the sodar receiver from the reflection of a single-frequency sound transmission and its characteristic properties depending on the physical state of the atmosphere. Similar spectra were parameterised with a single numerical value using statistical methods. It was found that, in some cases preceding high concentrations of PM 10 , the spectral parameters had similar values. This made it possible to develop a forecasting method for such concentrations by using data mining to search for conditions in historical data closest to the state of the atmosphere at the time of forecasting. In this part of the study, data from 2017–2018 were used. In the next step, three methods of using the sodar data developed for PM 10 prediction were proposed, comparing them with the method without sodar use. The study results were tested on independent material using data concerning the episodes of high concentrations of pollutants from October 2021 to March 2022 in Krakow. The findings were considered to be encouraging, also taking into account the speed and low cost of preparing the forecast. [ABSTRACT FROM AUTHOR]

Optical beam propagation through the atmosphere is suffering from turbulence condition and scattering due to the refractive index effects on propagation. In this paper, we study optical beam propagation under the UAE's weather conditions. An outdoor test was carried out to gather the atmosphere parameters (temperature, wind, humidity, and refractive index) and feed them to a beam propagation model. The beam centroid was determined to study and predict the effects on it at different periods of the day. [ABSTRACT FROM AUTHOR]

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