Thermal Inversion Research Articles

How does air pollution affect corporate information environment?

AbstractIn this article I examine the causal impact of air pollution on the corporate information environment. My empirical findings indicate that firms located in cities with severe air pollution tend to experience higher information asymmetry. The economic mechanisms behind this casual association come from the negative impact of air pollution on corporate governance and managerial human capital. Specifically, the positive causal association between air pollution and corporate information asymmetry is less pronounced for firms with stronger corporate governance and better managerial ability. In addition, firms exposed to more severe air pollution tend to have fewer board meetings. All main empirical findings are robust to a system generalized method of moments estimation, two‐stage least squares tests using thermal inversions as an instrumental variable, regression discontinuity tests based on the Huai River policy, and difference‐in‐difference estimations based on the 2013 Clean Air Action Plan in China. Furthermore, all main findings are confirmed by robustness tests, such as alternative proxies of air pollution and information asymmetry, and the exclusion of first‐tier cities.

Long-term variability of satellite derived total alkalinity in the southwest Bay of Bengal

The seasonal and inter-annual variability of Total Alkalinity (TA) concentration was studied in the Bay of Bengal from 2003 to 2019 by using MODIS-Aqua derived sea surface temperature (SST) and sea surface salinity (SSS) products. The satellite derived TA showed a positive relationship with in-situ TA with (R2 = 0.67, RMSE = ±27.53 μMol/kg, SEE = ±32.16 and uncertainty error = 2287μMol/kg). The seasonal SST, SSS and TA portray the clear seasonal pattern between the seasons without any rapid change increase or decrease in trend observed over the years. In contrast to other seasons, the spring inter-monsoon was observed to have a warm surface water temperature with high salinity and TA. Strong wind and excessive cloud cover during the summer monsoon result in the reduction of ocean surface heat, which favours sea surface cooling and shallow mixed layer depth, resulting in low SST, SSS, and TA compared to the spring inter-monsoon. During fall inter-monsoon, the reversal of East India coastal current directs warm water from north to south and the weak wind that prevails in this region enhances stratification. During winter, low-saline water compensates the static stability loss by thermal inversion from the sea surface resulting in surface cooling with coldest SST, low SSS and TA during this period.

Assessment of Individual-Level Exposure to Airborne Particulate Matter during Periods of Atmospheric Thermal Inversion.

Air pollution exposure is harmful to human health and reducing it at the level of an individual requires measurements and assessments that capture the spatiotemporal variability of different microenvironments and the influence of specific activities. In this paper, activity-specific and general indoor and outdoor exposure during and after a period of high concentrations of particulate matter (PM), e.g., an atmospheric thermal inversion (ATI) in the Ljubljana subalpine basin, Slovenia, was assessed. To this end, personal particulate matter monitors (PPM) were used, worn by participants of the H2020 ICARUS sampling campaigns in spring 2019 who also recorded their hourly activities. ATI period(s) were determined based on data collected from two meteorological stations managed by the Slovenian Environmental Agency (SEA). Results showed that indoor and outdoor exposure to PM was significantly higher during the ATI period, and that the difference between mean indoor and outdoor exposure to PM was much higher during the ATI period (23.0 µg/m3) than after (6.5 µg/m3). Indoor activities generally were associated with smaller differences, with cooking and cleaning even having higher values in the post-ATI period. On the other hand, all outdoor activities had higher PM values during the ATI than after, with larger differences, mostly >30.0 µg/m3. Overall, this work demonstrated that an individual-level approach can provide better spatiotemporal resolution and evaluate the relative importance of specific high-exposure events, and in this way provide an ancillary tool for exposure assessments.

Rotor orientation direction controls geometric curvature and chirality for assemblies of motor amphiphiles in water

AbstractControl over geometric curvature and chirality of assemblies in pure aqueous media is key to the design of responsive materials and molecular machines. Here we show how aggregate geometric curvature and chirality of motor amphiphiles could be switched from bicontinuous calabashes to nanoribbons or from vesicles to nanoribbons by modulating rotor orientation direction with dual light/heat stimuli to influence spontaneous curvature in assemblies. The photoisomerization and thermal helix inversion processes of molecular motors have been studied at the molecular level, and the transformation of supramolecular assemblies has been investigated at the microscopic level. The morphological evolution of the calabash‐shaped assembly can be kinetically captured, suggesting that the bicontinuous calabash‐shaped structures are different from the bowl‐shaped aggregates based on solvent‐driven assembly upon the addition of non‐solvent or solvent. The investigation of dual optical/thermal control of rotor orientation can provide a new strategy for tuning the geometric curvature and chirality of nanoassemblies at the nanoscale, arriving ultimately the clusteroluminescence through‐space electronic communication at responsive supramolecular nanosystems.

Impact of Air Pollution on Mental Health in India

There is extensive evidence linking air pollution exposure to physical health. Less is known about the mental health impacts of poor air quality, especially in developing countries. We use data from India and estimate the causal impact of air pollution exposure on feeling sad, experiencing cognitive difficulties, and feeling unable to control and cope with important things in life. We instrument for air pollution exposure using the annual number of nighttime thermal inversions and show that air pollution exposure in the previous calendar year significantly worsens mental health in the current year. We examine potential mechanisms and find that air pollution exposure negatively impacts self-reported physical health, worsens respiratory conditions, and increases the likelihood of experiencing sleeping difficulties. Accounting for mental health impacts of pollution exposure is critical to accurately estimating the true health costs of air pollution and designing optimal environmental policy.

Chemical characteristics of three-stage fog water in an agricultural city in China

To investigate the relationships among the chemical compositions of fog droplets, atmospheric pollutants, and the fog microphysical characteristics, four fog cases were sampled in a comprehensive field experiment conducted at the Donghai site in an agricultural city, China, in the winter of 2020. The pH, electrical conductivity (EC), total ion concentration (TIC), and chemical compositions of the fog water were all size-dependent. High concentrations of non-sea-salt calcium (nssCa2+) and NH4+ led to the alkaline pH of 6.13–7.32. The TIC of fog water was relatively high, especially in small droplets of diameter within 4–16 μm (463527.9 μeq/L). The relatively high NO2− concentration was also found in the fog water, dominated by the non-homogeneous chemical reaction between NO2 and fog droplets. An interesting finding is that the TIC of fog water measured on December 12 was much higher than that measured on December 11. Compared to the first fog, the stronger thermal inversion and local emissions led to the higher concentration of atmospheric particles in the second fog. Generally, the relatively high concentration of atmospheric particles resulted in a large number of small-sized droplets, which had fast liquid-phase oxidation reaction rates and high gas-liquid conversion efficiencies, leading to a higher TIC in the fog water during the second fog.

The effect of air pollution on migrants’ permanent settlement intention: Evidence from China

Few studies have explored the relationship between air pollution and settlement intention. In this study, we fill the gap by investigating the impact of air pollution on migrants' settlement intention and analyzing its heterogeneous effect and potential mechanisms. We find migrants are more likely to settle down in cities with clean air than in those with dirty air. The results are consistent when different air quality indices are used and the endogeneity problem is mitigated using thermal inversion as an instrument for air quality. Heterogeneity analyses show that low-SES (social economic status) migrants are more likely to migrate out due to polluted air. The mechanisms results show that air quality may affect the long-term settlement intention of migrants through two channels: the direct subjective attitude effect and indirect health effect. In addition, we also find that air pollution only affects migrants' permanent settlement intention, while it has no impact on their short-run stay intention. Our results shed light on air pollution as an important contributor to migrants' migration and settlement choice and as a determinant in discussions on cities’ brain drain.

Effect of Temperature on Photoisomerization Dynamics of a Newly Designed Two-Stroke Light-Driven Molecular Rotary Motor.

The working mechanism of conventional light-driven molecular rotary motors, especially Feringa-type motors, contains two photoisomerization steps and two thermal helix inversion steps. Due to the existence of a thermal helix inversion step, both the ability to work at lower temperatures and the rotation speed are limited. In this work, a two-stroke light-driven molecular rotary motor, 2-(1,5-dimethyl-4,5-dihydrocyclopenta[b]pyrrol-6(1H)-ylidene)-1,2-dihydro-3H-pyrrol-3-one (DDPY), is proposed, which is capable of performing unidirectional and repetitive rotation by only two photoisomerization (EP→ZP and ZP→EP) steps. With trajectory surface-hopping simulation at the semi-empirical OM2/MRCI level, the EP→ZP and ZP→EP nonadiabatic dynamics of DDPY were systematically studied at different temperatures. Both EP→ZP and ZP→EP photoisomerizations are on an ultrafast timescale (ca. 200–300 fs). The decay mode of EP→ZP photoisomerization is approximately bi-exponential, while that of ZP→EP photoisomerization is found to be periodic. For EP and ZP isomers of DDPY, after the S→S excitation, the dynamical processes of nonadiabatic decay are both followed by twisting about the central C=C double bond and the pyramidalization of the C atom at the stator-axle linkage. The effect of temperature on the nonadiabatic dynamics of EP→ZP and ZP→EP photoisomerizations of DDPY has been systematically investigated. The average lifetimes of the S excited state and quantum yields for both EP→ZP and ZP→EP photoisomerization are almost temperature-independent, while the corresponding unidirectionality of rotation is significantly increased (e.g., 74% for EP→ZP and 72% for ZP→EP at 300 K vs 100% for EP→ZP and 94% for ZP→EP at 50 K) with lowering the temperature.

Air pollution and political trust in local government: Evidence from China

While it is well-established that air pollution damages health and inhibits productivity, the political cost of air pollution remains poorly understood. We estimate the causal effect of air pollution on political trust in local government in China, which underpins the stability of the authoritarian state. Combining a nationally representative longitudinal survey with satellite derived PM2.5 concentrations, we find that a one μg/m³ exogenous increase in PM2.5 concentrations, due to atmospheric thermal inversion, reduces trust in local government by 4.1 per cent of one standard deviation. This implies that if China were to reduce PM2.5 emissions to the annual standard of 35 μg/m³ mandated by the Chinese government, this would boost trust in local government by 21.2 per cent evaluated at the mean. We examine the underlying transmission channels and find that prolonged exposure to PM2.5 lowers citizens’ life satisfaction and evaluation of local government performance, induces adverse health effects, imposes additional financial burden and, albeit to a lesser extent, reduces household income.

The Impact of Air Pollution on the Protection of World Cultural Heritage in China.

The damage of air pollution to cultural heritage is widely known. However, the quantitative effects still need to be explored at a holistic level. Different from existing research which focuses on the “model calculation” methods, this paper uses an econometric approach to assess the overall impact of air pollution on the sustainable protection of world cultural heritage in China. Based on the data of the annual monitoring report from 2014 to 2020 released by the China World Cultural Heritage Monitoring Platform, this paper uses the thermal inversion as an instrument variable of air pollution to estimate the overall effects of air pollution on all world cultural heritage sites in China. The results indicate that almost all the air pollutants (except for CO) have significantly negative effects on heritage. The damaging effects of gaseous pollutants including SO2, NO2 and O3 is greater than that of particulate pollutants such as PM2.5 and PM10. Rainfall can exacerbate the worsening effects of gaseous pollutants, but will mitigate the negative effects of particulate pollutants; the windy weather may weaken the negative impact. In addition, environmental regulations from the local government can also alleviate the negative influence of air pollution on heritage protection. This research can provide a more comprehensive environmental prevention policy reference for the protection of world cultural heritage.

K2 and Spitzer phase curves of the rocky ultra-short-period planet K2-141 b hint at a tenuous rock vapor atmosphere

K2-141 b is a transiting, small (1.5 R⊕) ultra-short-period (USP) planet discovered by the Kepler space telescope orbiting a K-dwarf host star every 6.7 h. The planet's high surface temperature of more than 2000 K makes it an excellent target for thermal emission observations. Here we present 65 h of continuous photometric observations of K2-141 b collected with Spitzer's Infrared Array Camera (IRAC) Channel 2 at 4.5 μm spanning ten full orbits of the planet. We measured an infrared eclipse depth of ${f_{{{\rm{p}} \mathord{\left/ {\vphantom {{\rm{p}} {{{\rm{f}}_{\rm{*}}}}}} \right. \kern-\nulldelimiterspace} {{{\rm{f}}_{\rm{*}}}}}}} = 142.9_{ - 39.0}^{38.5}$ ppm and a peak to trough amplitude variation of $A = 120.6_{ - 43.0}^{42.3}$ ppm. The best fit model to the Spitzer data shows no significant thermal hotspot offset, in contrast to the previously observed offset for the well-studied USP planet 55 Cnc e. We also jointly analyzed the new Spitzer observations with the photometry collected by Kepler during two separate K2 campaigns. We modeled the planetary emission with a range of toy models that include a reflective and a thermal contribution. With a two-temperature model, we measured a dayside temperature of ${T_{{\rm{p,d}}}} = 2049_{ - 359}^{362}$ K and a night-side temperature that is consistent with zero (Tp,n < 1712 K at 2σ). Models with a steep dayside temperature gradient provide a better fit to the data than a uniform dayside temperature (ΔBIC = 22.2). We also found evidence for a nonzero geometric albedo ${A_{\rm{g}}} = 0.282_{ - 0.078}^{0.070}$. We also compared the data to a physically motivated, pseudo-2D rock vapor model and a 1D turbulent boundary layer model. Both models fit the data well. Notably, we found that the optical eclipse depth can be explained by thermal emission from a hot inversion layer, rather than reflected light. A thermal inversion may also be responsible for the deep optical eclipse observed for another USP, Kepler-10 b. Finally, we significantly improved the ephemerides for K2-141 b and c, which will facilitate further follow-up observations of this interesting system with state-of-the-art observatories such as James Webb Space Telescope.

The Influence of Strain on the Rotation of an Artificial Molecular Motor

AbstractIn artificial small‐molecule machines, molecular motors can be used to perform work on coupled systems by applying a mechanical load—such as strain—that allows for energy transduction. Here, we report how ring strain influences the rotation of a rotary molecular motor. Bridging the two halves of the motor with alkyl tethers of varying sizes yields macrocycles that constrain the motor's movement. Increasing the ring size by two methylene increments increases the mobility of the motor stepwise and allows for fine‐tuning of strain in the system. Small macrocycles (8–14 methylene units) only undergo a photochemical E/Z isomerization. Larger macrocycles (16–22 methylene units) can perform a full rotational cycle, but thermal helix inversion is strongly dependent on the ring size. This study provides systematic and quantitative insight into the behavior of molecular motors under a mechanical load, paving the way for the development of complex coupled nanomachinery.

The Influence of Strain on the Rotation of an Artificial Molecular Motor.

In artificial small‐molecule machines, molecular motors can be used to perform work on coupled systems by applying a mechanical load—such as strain—that allows for energy transduction. Here, we report how ring strain influences the rotation of a rotary molecular motor. Bridging the two halves of the motor with alkyl tethers of varying sizes yields macrocycles that constrain the motor's movement. Increasing the ring size by two methylene increments increases the mobility of the motor stepwise and allows for fine‐tuning of strain in the system. Small macrocycles (8–14 methylene units) only undergo a photochemical E/Z isomerization. Larger macrocycles (16–22 methylene units) can perform a full rotational cycle, but thermal helix inversion is strongly dependent on the ring size. This study provides systematic and quantitative insight into the behavior of molecular motors under a mechanical load, paving the way for the development of complex coupled nanomachinery.

Will air pollution affect entrepreneurial activity? Evidence from China

ABSTRACT This is the first study to examine the empirical evidence on the effect of air pollution on entrepreneurial activity, which fills the research gaps in the relevant literature and provides perspectives on both pollution avoidance behaviour and influence on entrepreneurial activity. Moreover, we explored the innovative and unconventional big data of entrepreneurial activity, which was measured at the county level from 2000 to 2019, and used thermal inversion as an instrumental variable to reduce endogenous bias. Based on the regression analysis, haze pollution inhibits entrepreneurial activity. Meanwhile, the results also show geographic differences. In underdeveloped and non-resource-based regions, the inhibiting effect is more severe. Therefore, air pollution management is an adequate assurance of increasing entrepreneurial activity.

The GAPS Programme at TNG

The detection of lines in emission in planetary atmospheres provides direct evidence of temperature inversion. We confirm the trend of ultra-hot Jupiters orbiting A-type stars that show temperature inversions on their daysides by detecting metals emission lines in the dayside of KELT-20b. We first detected the planetary emission by using the G2 stellar mask of the HARPS-N pipeline, which is mainly composed of neutral iron lines, as a template. Using neutral iron templates, we performed a retrieval of the atmospheric temperature-pressure profile of the planet, confirming a thermal inversion. Then we created models of planetary emission of different species using the retrieved inverted temperature-pressure profile. By using the cross-correlation technique, we detected Fe I, Fe II, and Cr I at signal-to-noise ratio levels of 7.1, 3.9, and 3.6, respectively. The latter was detected in emission in the atmosphere of an exoplanet for the first time. Contrary to Fe I, Fe II and Cr I were detected only after the occultation and not before, hinting at different atmospheric properties in view during the pre- and post-occultation orbital phases. A further retrieval of the temperature-pressure profile performed independently during the pre- and post-occultation phases, while not highly significant, points to a steeper thermal inversion in the post-occultation.

Patchy Nightside Clouds on Ultra-hot Jupiters: General Circulation Model Simulations with Radiatively Active Cloud Tracers

The atmospheres of ultra-hot Jupiters have been characterized in detail through recent phase curve and low- and high-resolution emission and transmission spectroscopic observations. Previous numerical studies have analyzed the effect of the localized recombination of hydrogen on the atmospheric dynamics and heat transport of ultra-hot Jupiters, finding that hydrogen dissociation and recombination lead to a reduction in the day-to-night contrasts of ultra-hot Jupiters relative to previous expectations. In this work, we add to previous efforts by also considering the localized condensation of clouds in the atmospheres of ultra-hot Jupiters, their resulting transport by the atmospheric circulation, and the radiative feedback of clouds on the atmospheric dynamics. To do so, we include radiatively active cloud tracers into the existing MITgcm framework for simulating the atmospheric dynamics of ultra-hot Jupiters. We take cloud condensate properties appropriate for the high-temperature condensate corundum from CARMA cloud microphysics models. We conduct a suite of general circulation model (GCM) simulations with varying cloud microphysical and radiative properties, and we find that partial cloud coverage is a ubiquitous outcome of our simulations. This patchy cloud distribution is inherently set by atmospheric dynamics in addition to equilibrium cloud condensation, and causes a cloud greenhouse effect that warms the atmosphere below the cloud deck. Nightside clouds are further sequestered at depth due to a dynamically induced high-altitude thermal inversion. We post-process our GCMs with the Monte Carlo radiative transfer code gCMCRT and find that the patchy clouds on ultra-hot Jupiters do not significantly impact transmission spectra but can affect their phase-dependent emission spectra.

Physical and Thermal Properties Analysis of Hematite for Thermal Heat Storage.

Energy sustainability represents an important research topic for aiding decreasing energy dependence and slowing down climate changes. In this context, solutions using thermal energy storage through rock start to emerge, due to its natural benefits, when compared to more polluting alternatives. To understand whether a rock material can be considered a good thermal energy storage material for such solutions, it is necessary to evaluate the physical, chemical and thermal properties of such materials. Therefore, it becomes essential to understand how heat propagates in the rock and how voids influence the thermal properties. To achieve these goals, hematite ore from Moncorvo, Northeastern Portugal was used, in particular, to study the effect of grain size on thermal properties for three different sized lots. Chemical and physical changes between heated and unheated lots were detected using X-ray diffraction and particle size, as well as X-ray fluorescence analysis. Regarding thermal properties, a hot wire method approach was used with seven thermocouples. Additionally, a thermal inversion model to simulate the heat exchanges was also proposed, allowing changing the properties of the constituents, to fit the theoretical and experimental temperature curve. Furthermore, the model reveals how heat propagates inside the reservoir filled with hematite ore.

Linking Atmospheric Chemistry of the Hot Jupiter HD 209458b to Its Formation Location through Infrared Transmission and Emission Spectra

The elemental ratios of carbon, nitrogen, and oxygen in the atmospheres of hot Jupiters may hold clues to their formation locations in the protostellar disk. In this work, we adopt gas-phase chemical abundances of C, N, and O from several locations in a disk chemical kinetics model as sources for the envelope of the hot Jupiter HD 209458b and evolve the atmospheric composition of the planet using a 1D chemical kinetics model, treating both vertical mixing and photochemistry. We consider two atmospheric pressure-temperature profiles, one with and one without a thermal inversion. From each of the resulting 32 atmospheric composition profiles, we find that the molecules CH4, NH3, HCN, and C2H2 are more prominent in the atmospheres computed using a realistic noninverted P–T profile in comparison to a prior equilibrium chemistry based work, which used an analytical P–T profile. We also compute the synthetic transmission and emission spectra for these atmospheres and find that many spectral features vary with the location in the disk where the planetary envelope was accreted. By comparing with the species detected using the latest high-resolution ground-based observations, our model suggests that HD 209458b could have accreted most of its gas between the CO2 and CH4 ice lines with a supersolar C/O ratio from its protostellar disk, which in turn directly inherited its chemical abundances from the protostellar cloud. Finally, we simulate observing the planet with the James Webb Space Telescope (JWST) and show that differences in spectral signatures of key species can be recognized. Our study demonstrates the enormous importance of JWST in providing new insights into hot-Jupiter formation environments.

On the Dayside Atmosphere of WASP-12b

The atmospheric structure of WASP-12b has been hotly contested for years, with disagreements on the presence of a thermal inversion as well as the carbon-to-oxygen ratio, C/O, due to retrieved abundances of H2O, CO2, and other included species such as HCN and C2H2. Previously, these difficult-to-diagnose discrepancies have been attributed to model differences; assumptions in these models were thought to drive retrievals toward different answers. Here, we show that some of these differences are independent of model assumptions and are instead due to subtle differences in the inputs, such as the eclipse depths and line-list databases. We replicate previously published retrievals and find that the retrieved results are data driven and are mostly unaffected by the addition of species such as HCN and C2H2. We also propose a new physically motivated model that takes into consideration the formation of H− via the thermal dissociation of H2O and H2 at the temperatures reached in the dayside atmosphere of WASP-12b, but the data’s current resolution does not support its inclusion in the atmospheric model. This study raises the concern that other exoplanet retrievals may be similarly sensitive to slight changes in the input data.

Heat stress in Beijing and its relationship with boundary layer structure and air pollution

Both extreme heat and heavy air pollution can cause adverse health impacts on urban inhabitants. To understand heat stress and its relationship with boundary layer structure and air pollution in Beijing, this study analyzed surface meteorological observations, radiosonde measurements, and ground-level PM2.5 and O3 concentrations in summer from 2015 to 2019, in conjunction with simulated air quality and MERRA-2 data. We measured the heat stress using a heat index that combines temperature and humidity to quantify the sensible temperature as perceived by humans, and found that high heat risk in Beijing was often associated with a low boundary layer height and poor air quality. To reveal the underlying physical mechanism involved, we objectively classified the synoptic conditions in North China. The typical synoptic pattern associated with the coupling of heat and pollution in Beijing was found to feature a southeast-to-north pressure gradient at the 700-hPa level, leading to westward warm advection above planetary boundary layer (PBL) and southward movement of warm, humid, and polluted air masses within the PBL towards Beijing. The elevated warm advection can enhance the capping of thermal inversion over the PBL and suppress the PBL's development and the vertical dispersion of pollutants. With mountains to the north and west, pollutants and heat can be trapped in a limited volume in Beijing, increasing the health risk from heat and pollution. These findings on the meteorological mechanisms of the coupling between heat and pollution in Beijing may have important implications for limiting the current health risk and preparing for any projected changes in it in the future.