Vertical Inversion Research Articles

Comparative Study on the Vertical Column Concentration Inversion Algorithm of Tropospheric Trace Gas Based on the MAX-DOAS Measurement Spectrum

The tropospheric vertical column concentration (VCDtrop) of NO2, SO2, and HCHO was retrieved, respectively, by employing the geometric method (Geomtry), simplified model method (Model), and look-up table method (Table) with the observation spectra of the multi-axis differential absorption spectroscopy instrument (MAX-DOAS). The correlation and relative differences of the inversion results obtained by these three algorithms, as well as the changes in quantiles, were explored. The comparative analysis reveals that the more concentrated the vertical distribution height of gas components is in the near-surface layer, the better the conformity of the VCDtrop retrieved by different algorithms. However, the increase in relative differences is also related to the diurnal variation of gas components. The influence of aerosols on the inversion of the VCDtrop is greater than the change in the vertical distribution height of the gas component itself. The near-surface concentration and distribution height of gas components are the internal factors that give rise to relative differences in the inversion of the VCDtrop by different algorithms, while aerosols are one of the extremely important external reasons. The VCDtrop inverted by Geomtry without considering the influence of aerosols is generally larger except for NO2. Model sets up aerosols in accordance with the height and meteorological conditions of the atmospheric environment. Table can invert the aerosol profile in real time. Compared with Model, it shows a significant improvement in the refined setting of aerosols. Moreover, while obtaining the vertical distribution of aerosols, it can invert the diurnal variation of the VCDtrop. The VCDtrop inverted by Table is the smallest, and the relative difference with Model is on average about 10% smaller. The relative difference of the VCDtrop for the same height (aerosol optical thickness) quantile is 7–15% (about 25% lower on average). When comparing the inversion results of Table with the Ozone Monitoring Instrument (OMI) satellite product, the MAX-DOAS inversion results of NO2, SO2, and HCHO are all larger than the OMI product. This is related to the different observation methods of the MAX-DOAS and OMI and the configuration between the aerosol layer and the distribution height of gas components.

Suction Feeding Turned on Its Head: A Functional Novelty Facilitates Lower Jaw Protrusion.

Functional novelties play important roles in creating new ways for organisms to access resources. In fishes, jaw protrusion has been attributed to the massive diversity of suction-based feeding systems, facilitating the dominant mode of prey capture in this group. Nearly all fishes that feed by suction use upper jaw protrusion, achieved by rotation of the mandible at its base, which then transmits forward motion to independently mobile upper jaw bones. In this study, by contrast, we explore an unusual form of lower jaw protrusion in the freshwater invertivore, Nannocharax fasciatus, enabled by a novel intramandibular joint (IMJ). We combine morphological, kinematic, and biomechanical data to show that the added mobility created by the IMJ influences the pattern of suction-based prey capture movements and contributes to lower jaw protrusion (increasing it by 25%, based on biomechanical modeling). Interestingly, the upper jaw bones are fused in N. fasciatus and rotate about a single fixed joint, like the lower jaws of most other suction feeding fishes. We suggest that this vertical inversion of the jaw protrusion mechanism for ventrally directed suction-feeding on benthic prey is a likely exaptation, as the IMJ is used for biting in related taxa. This work highlights the ability of novelties to facilitate ecological specialization by enabling new functional capabilities.

Multi-wavelength dataset of aerosol extinction profiles retrieved from GOMOS stellar occultation measurements

Abstract. In this paper, we present the new multi-wavelength dataset of aerosol extinction profiles, which are retrieved from the averaged transmittance spectra by the Global Ozone Monitoring by Occultation of Stars instrument aboard the Envisat satellite. Using monthly and zonally averaged transmittances as a starting point for the retrievals enables us to improve the signal-to-noise ratio and eliminate possible modulation of transmittance spectra by uncorrected scintillations. The two-step retrieval method is used: the spectral inversion is followed by the vertical inversion. The spectral inversion relies on the removal of contributions from ozone, NO2, NO3 and Rayleigh scattering from the optical depth spectra for each ray perigee altitude. In the vertical inversion, the profiles of aerosol extinction coefficients at several wavelengths are retrieved from the collection of slant aerosol optical depth profiles. The retrieved aerosol extinction profiles (FMI-GOMOSaero dataset v1) are provided in the altitude range 10–40 km at wavelengths of 400, 440, 452, 470, 500, 525, 550, 672 and 750 nm for the whole GOMOS operating period from August 2002 to March 2012. Extensive intercomparisons of the retrieved FMI-GOMOSaero aerosol profiles with aerosol profile data from other satellite instruments at several wavelengths have been performed. It is found that the average difference between FMI-GOMOSaero and other datasets is within 20 %–40 % in the lower and middle stratosphere, the standard deviation is ∼ 20 %–50 %, and the correlation coefficient of the time series is 0.65–0.85. The created FMI-GOMOSaero dataset can be used in merged datasets of stratospheric aerosols. It might be also used as a priori information for satellite retrievals during 2002–2012.

Three-dimensional forest structure features extraction based on TomoSAR

Abstract. Forest structure is an important indicator for evaluating forest ecosystem and an indispensable input parameter for estimating forest carbon sink. Synthetic Aperture Radar (SAR) Tomography (TomoSAR), as a novel microwave remote sensing technique with 3D imaging capability, has been demonstrated to be an valuable tool for accurate inversion of forest structure. At present, the forest vertical structure parameters inversion is almost all concentrated on the forest height estimation. However, the spatial structure of forests is complex, and it is not enough to only use the forest height to express the forest structure. This fails to identify tree canopy, branch layer and underlying vegetation layer, etc., resulting in the partial and inaccurate forest vertical structure information. To solve this problem, this paper constructs 3D structural indices from tomograms, namely Horizontal Structure Index (HS) and Vertical Structure Index (VS). The HS primarily describes canopy density, compensating for the lack of information on the horizontal dimension of forest structure provided by traditional TomoSAR techniques; while VS describes the complexity of canopy distribution in the altitude direction, further enriching information on forest structure vertically. In order to verify their feasibility and validity, HS and VS are extracted using six fully-polarized L-band SAR images covering the Krycklan watershed in Sweden. Moreover, the accuracy is verified by using external high-precision LiDAR data. The results indicate a strong correlation between the structural indices extracted from TomoSAR and those extracted from LiDAR.

Joint inversion method of multipoint ambient noise horizontal-to-vertical spectral ratio for 3-D velocity structure of local site and its application

SUMMARY The diffusion field theory has been widely used to interpret ambient noise wave fields. Based on this theory, 1-D subsurface velocity structure inversion method is developed. However, few studies have referred to the noise horizontal to vertical (NHV) spectral ratio inversion of 3-D subsurface velocity structures, and almost no effective 3-D NHV inversion tools have been developed. To develop a useful tool for obtaining 3-D soil layer velocity structures, we combined the NHV forward calculation formula derived from diffusion field theory with the guided Monte Carlo algorithm and then extended the single-point NHV inversion to multipoint joint inversion through a joint objective function. Subsequently, a new 3-D soil layer velocity structure inversion method was proposed. Subsequently, a synthetic 2-D case was used to verify the proposed method. Finally, the proposed method was applied to the Xiangtang Array in Tangshan, China, to identify the 3-D velocity structures of the site based on noise observations. The results show that the proposed multipoint joint 3-D inversion method is effective for identifying 3-D underground velocity structures.

An Airborne Visible Light Lidar’s Methodology for Clear Air Turbulence Detection Based on Weak Optical Signal

A clear air turbulence (CAT) detection method using a 532 nm visible light airborne laser radar (LiDAR) system is proposed to address the urgent challenge in the aviation safety field. This method is based on the indirect detection technique of atmospheric molecular density for CAT and utilizes the strong aerosol scattering absorption characteristics of the iodine molecular 1109 absorption line to eliminate the interference of aerosol scattering and extinction on the weak molecular backscattering signal caused by CAT. This enables CAT detection under conditions where traditional ultraviolet LiDAR systems fail to function properly due to aerosol presence. The influence of axial wind speed and atmospheric temperature variations on the molecular backscattering spectrum in the aircraft flight path is studied, and a formula for vertical wind speed inversion in the CAT field is derived. The 532 nm airborne LiDAR CAT detection theoretical model and system architecture are presented. Through simulation analysis, the CAT detection range of the visible light LiDAR system is evaluated under different aircraft cruising altitudes and turbulence intensities. The results indicate that, with the proposed LiDAR system, the aerosol scattering influence can be effectively suppressed, and CAT can be detected up to 7 km for light-to-moderate turbulence and 10 km for moderate turbulence ahead of the aircraft when traditional ultraviolet LiDAR systems fail as the backscattering coefficient ratio between aerosol and molecule reaches the 10−1 condition. Based on this finding, a suggestion is made to construct a dual-wavelength (ultraviolet-visible) LiDAR system for CAT detection, aiming to solve the full coverage problem of CAT detection under various aerosol conditions. This study has a reference value for promoting the early resolution of CAT detection in the aviation field.

Construction of pseudo-Hessian for vertical seismic profile full waveform inversion

The pseudo-Hessian matrix has been widely developed and applied to full waveform inversion to reduce the computational cost of obtaining the Hessian and its inverse matrix. Because the conventional pseudo-Hessian matrix assumes a surface seismic profiling geometry, this conventional method is compatible only with horizontally deployed sources and receiver geometries and cannot reflect the geometrical spreading effect of vertically deployed receivers. To enable the pseudo-Hessian to properly consider vertically deployed receiver locations and the geometrical spreading inherent in vertical seismic profiling data, we re-formulate part of the pseudo-Hessian matrix formulation. We verify our new scheme by directly calculating the Hessian matrices for a simple 1D model and conducting inversion tests with synthetic data sets. A comparison to the approximated Hessian matrix confirms that the vertical seismic profiling pseudo-Hessian provides better agreement with the approximated Hessian than the conventional pseudo-Hessian. In addition, we describe two numerical tests using multi-offset synthetic vertical seismic profiling data sets. When we apply the conventional pseudo-Hessian matrix to invert the synthetic data, we find that the inversion process cannot properly invert far offset data. However, we find that the pseudo-Hessian regarding vertical seismic profiling geometry allows the inversion process to invert far offset data and produces fewer artifacts than the conventional method. This study demonstrates that the vertical seismic profiling pseudo-Hessian matrix represents an alternative method that is necessary for the calculation of the pseudo-Hessian matrix for full waveform inversion with vertical seismic profiling using the Gauss–Newton method.

Iterative approaches for regional Moho determination using on-orbit gravity gradients: A case study in Qinghai-Tibet Plateau and its near zone

Summary Moho determination is an important issue in studying the Earth’s interior structure. In accordance with the isostasy-compensation hypothesis in geodesy, it is possible to recover regional or global Moho by employing gravimetric data. The non-linear property is one of the main difficulties in solving the inverse problem of isostasy. To effectively address this issue, we propose an improved iterative inversion method that combines three-dimensional integration and linear regularization to achieve an approximate non-linear solution. To estimate the contributions of different components in the gravity-gradient tensor from the Gravity field and steady-state Ocean Circulation Explorer (GOCE), other than the vertical component, we additionally develop two joint inversion scenarios that utilize diagonal horizontal components and all five non-vertical components. The validating experiments are implemented in Qinghai-Tibet Plateau and its near zone. Simulations and applications illustrate that horizontal responses of Moho undulation are also significant. Yet the off-diagonal components provide minimal contributions, adding only 0.25 km of bias to the joint inversion results. Truncation effects serve as the primary source of systematic errors, resulting in ∼1 km error in vertical inversion results and ∼2.3 km error in joint inversion results. Then, the gravimetric Moho results are compared with CRUST1.0, and they show a generally strong correlation. Differences are obvious at the northern and eastern margins of the plateau. It is maybe due to the local changes in crust-mantle density contrasts. Upwelling of asthenospheric materials and fluid flow in the middle-lower crust are the two main factors. Based on high-precision satellite gravimetry, our study could provide new insights into the tectonic structure of Qinghai-Tibet Plateau.

229 nm far-ultraviolet second harmonic generation in a vertical polarity inverted AlN bilayer channel waveguide

Far-UV light sources have attracted much attention for human-safe viral inactivation and bacterial disinfection. Due to large optical nonlinearity and transparency to this wavelength region, AlN is a promising material for compact and low-cost far-UV second harmonic generation (SHG) devices. In this study, a transverse quasi-phase-matched AlN channel waveguide with vertical polarity inversion was designed and fabricated. From wavelength spectra and a pump power dependence of an SH intensity, far-UV SHG via the largest nonlinear optical tensor component d 33 was successfully confirmed under ultrashort pulse laser excitation.

A Dual-Baseline PolInSAR Method for Forest Height and Vertical Profile Function Inversion Based on the Polarization Coherence Tomography Technique

Forest height and vertical structure profile functions can be estimated using polarimetric interferometric synthetic aperture radar (PolInSAR) data based on the random volume over ground (RVoG) model and polarization coherence tomography (PCT) theory, respectively. For each resolution cell, considering different forest vertical scattering structure functions to solve the corresponding forest height, the accuracy of PolInSAR forest height inversion will be improved. In this study, a forest vertical structure profile function and forest height inversion algorithm based on PCT technology was developed by using dual-baseline PolInSAR data. Then the deviation of forest height was corrected according to the inverted forest vertical structure. Finally, the LiDAR and PolInSAR data were employed to verify the proposed method. The experimental results show that the accuracy of the proposed method (tropical forest: RMSE = 5.96 m, boreal forest: RMSE = 3.11 m) is 25.5% and 30.43% higher than that of the dual-baseline RVoG model algorithm (tropical forest: RMSE = 8 m, boreal forest: RMSE = 4.47 m).

Importance of source structure on complex organics emission

Context. The hot molecular core phase of massive star formation shows emission from complex organic molecules. However, these species are only detected toward a fraction of high-mass protostars. In particular, there is a spread of ~2 orders of magnitude in methanol emission intensity from high-mass protostars. Aims. The goal of this work is to answer the question of whether high-mass disks can explain the lack of methanol emission from some massive protostellar systems. Methods. We considered an envelope-only and an envelope-plus-disk model and used the code RADMC-3D to calculate the methanol emission. High and low millimeter (mm) opacity dust (representing large and small dust distributions) were considered for both models separately, and the methanol abundance was parameterized. Viscous heating was included due to the high accretion rates of these objects in the disk. Results. In contrast with low-mass protostars, the presence of a disk does not significantly affect the temperature structure and methanol emission. The shadowing effect of the disk is not as important for high-mass objects, and the disk midplane is hot because of viscous heating, which is effective due to the high accretion rates. The methanol emission is lower for models with high mm opacity dust because the dust attenuation blocks the emission in the envelope and hides it in the disk through continuum oversubtraction, but the disk needs to be large for this to become effective. A minimum disk size of ~2000–2500 au is needed (at L = 104 L⊙) with high mm opacity dust for drop of a factor of about one order of magnitude in the methanol emission compared with the envelope-only models with low mm opacity dust. Consistent with observations of infrared absorption lines toward high-mass protostars, we find a vertical temperature inversion, that is, higher temperatures in the disk midplane than the disk surface, at radii ≲50 au for models with L = 104 L⊙ and high mm opacity dust as long as the envelope mass is ≳550 M⊙ (Ṁ = 3.6 × 10−3 M⊙ yr−1). Conclusions. The large observed scatter in methanol emission from massive protostars can be mostly explained toward lower-luminosity objects (~103 L⊙) with the envelope-plus-disk models including low and high mm opacity dust. The methanol emission variation toward sources with high luminosities (≳104 L⊙) cannot be explained by models with or without a disk with a relatively high gas-phase abundance of methanol. However, the luminosity-to-mass ratios of these objects suggest that they might be associated with hypercompact or ultracompact HII regions. Therefore, the low methanol emission toward the high-luminosity sources can be explained by them hosting an HII region in which methanol is absent.

Retrospective study of concomitant hypodontia and hyperdontia in 145 subjects.

This study aims to investigate the incidence and clinical characteristics of concomitant hypodontia and hyperdontia (CHH) by performing panoramic radiographs. A total of 41 648 panoramic radiographs of pediatric patients who were admitted to the hospitals from January 2019 to May 2021 were reviewed, and 145 CHH patients were included in the study. The presence of CHH was recorded. SPSS 24.0 software was used for statistical analysis. The prevalence of CHH was 0.35% (145/41 648). Males (102 cases) were obviously more than females (43 cases), and the difference between genders was statistically significant (P<0.001). The features of congenital permanent tooth loss in this group were predominantly 1 and 2 teeth missing and preferably mandibular lateral incisors and mandibular second premolars missing. The incidence of congenital permanent teeth loss was higher in the mandible than in the maxilla (P<0.001), but no difference was found in the distribution between left and right (P=0.84). The features of supernumerary teeth in this group were 1 and 2 teeth, mostly in the maxillary anterior area, mostly conical, mostly vertical inversion and orthotopic growth. CHH is a rare mixed numeric dental anomaly characterized by congenital missing teeth and supernumerary teeth occurring in the same individual. CHH cases are higher in men than in women. The characteristics of their hypodontia and hyperdontia are similar to those of patients with congenital permanent tooth absence or supernumerary teeth. Early diagnosis of the condition and a multidisciplinary approach for management of such case is recommended.

Expression of Concern: ADAD2 regulates heterochromatin in meiotic and post-meiotic male germ cells via translation of MDC1.

This Expression of Concern relates to J. Cell Sci. (2022) 135, jcs259196 (doi:10.1242/jcs.259196).Journal of Cell Science was contacted by a reader of the above article who alerted us to possible duplication of GAPDH western blot data in Fig. 1D and Fig. 3A to represent experimental groups at different developmental stages. This prompted us to examine the article figures for possible image duplications. Following examination of the figures, we were concerned about possible reuse of western blot images in Fig. 1D,E, Fig. 3A, Fig. S5B,D and Fig. S6A,D, as well as possible duplication of data in Fig. 1D.We contacted the corresponding author, Dr Elizabeth M. Snyder, to request original data for the western blots in Figs 1, 3, S5 and S6. Dr Snyder provided the requested data and explained that the reuse of control GAPDH, ADAD2 and histone H3 western blots in multiple figures is consistent with the experimental design, whereby genotype and loading controls were run once for each of the tissue sample panels analysed in the blots. At this stage, Dr Snyder also brought to our attention that an incorrect GAPDH control blot had been used for the 21 dpp samples in Fig. S5B and provided a version of Fig. S5 with an updated 21 dpp GAPDH image in Fig. S5B.After examination of the data provided by Dr Snyder, we had continued concerns about inconsistent reporting of developmental stage for the data in Fig. 3A, vertical inversion of ADAD2 blot data in Fig. 3A and Fig. S6D, the abovementioned use of incorrect GAPDH control data in Fig. S5B and its relationship to the 21 dpp GAPDH data in Fig. S5D, undeclared reuse of non-control eEF1G blot data in Fig. S5B and D, and the high degree of similarity in background features of the original blot data provided for adult and 21 dpp HP1β blots in Fig. 1D. We therefore invited Dr Snyder to provide further explanation of these issues.In her response, Dr Snyder informed us that the western blots in Fig. 3A are incorrectly described in the figure legend as showing samples from adult mice, when they instead show samples taken at 21 dpp, as is indicated in the main text. Dr Snyder also confirmed that the ADAD2 images in Fig. 3A and Fig. S6D are vertically inverted. Dr Snyder provided further details about the GAPDH data in Fig. S5B and D, confirming that the GAPDH blot in Fig. S5B and the 21 dpp GAPDH blot in Fig. S5D both show incorrect data, and informing us that the incorrect GAPDH data were also used to prepare the quantification shown in Fig. S5C. Dr Snyder also clarified that the eEF1G blot images in Fig. S5B and D show the same data, stating that declaration of this data duplication was omitted from the article in error. The data provided by Dr Snyder show that the images used to prepare the adult and 21 dpp HP1β blot panels in Fig. 1D were acquired with a 1 minute interval. In her response, Dr Snyder explained that, as the result of a data management error, the data used for these images in Fig. 1D appear to have been acquired by incorrectly saving two images of a single western blot, which is consistent with the high degree of similarity between the images. Dr Snyder provided technical replicate HP1β blot data for both the adult and 21 dpp samples.Dr Snyder also identified further issues in the figures while reviewing the data, which she has brought to our attention in the interests of transparency and ensuring an accurate public record. These include: (1) vertical inversion of the BRCA1 blot image in Fig. 3A; (2) vertical inversion of the KU80 blot image in Fig. S6D; (3) vertical inversion of the 21 dpp GAPDH blots in Fig. 1D, Fig. 3A and Fig. S6D; (4) incorrect cropping of the HP1α blot of samples from isolated cells in Fig. 1D, such that the figure does not show the HP1α band; and (5) incorrect cropping and horizontal inversion of the H3K9me3 blot of samples from isolated cells in Fig. 1E, such that incorrect lanes are shown for the different samples.We are grateful for Dr Snyder's cooperation throughout the course of investigating these issues. However, due to the number and range of issues in figure preparation and data management that affect multiple figures, we have referred this matter to Dr Snyder's institute, Rutgers University, for further investigation. In the interim, Journal of Cell Science is publishing this Expression of Concern to make readers aware of these issues.

Взаимообусловленность гидрохимических и гидродинамических процессов в эвапоритовых нефтегазоносных бассейнах

The article examines the reasons for the formation of vertical hydrochemical inversion within particular oil and gas basins and points out the role of waters of different genesis in the development of this phenomenon. The following processes of reverse hydrochemical zoning in the sedimentary cover are analyzed: thickening of heavy clay strata and the related squeezing of loosely bound waters, dehydration of clay minerals and catagenic fluid generation accompanying the transformation of organic matter into hydrocarbons of the petroleum series. The hydrochemical inversion at great depths is noted to occur and persist in the environment of the passive hydrodynamic regime; in closed water-drive systems, the demineralization of waters with depth causes the decrease in the hydrodynamic potential gradient, determining the migration pattern not only of water but also of hydrocarbons and, consequently, the location of oil and gas accumulation zones.

Application of multi-layer discrete anisotropic radiative transfer model in vertical distribution inversion of maize leaf area index

Application of multi-layer discrete anisotropic radiative transfer model in vertical distribution inversion of maize leaf area index

Field-free spin-orbit torque-induced switching of\xa0perpendicular magnetization in a ferrimagnetic layer with a vertical composition gradient

Current-induced spin-orbit torques (SOTs) are of interest for fast and energy-efficient manipulation of magnetic order in spintronic devices. To be deterministic, however, switching of perpendicularly magnetized materials by SOT requires a mechanism for in-plane symmetry breaking. Existing methods to do so involve the application of an in-plane bias magnetic field, or incorporation of in-plane structural asymmetry in the device, both of which can be difficult to implement in practical applications. Here, we report bias-field-free SOT switching in a single perpendicular CoTb layer with an engineered vertical composition gradient. The vertical structural inversion asymmetry induces strong intrinsic SOTs and a gradient-driven Dzyaloshinskii–Moriya interaction (g-DMI), which breaks the in-plane symmetry during the switching process. Micromagnetic simulations are in agreement with experimental results, and elucidate the role of g-DMI in the deterministic switching processes. This bias-field-free switching scheme for perpendicular ferrimagnets with g-DMI provides a strategy for efficient and compact SOT device design.

Subsurface Structure Models Of Sumbawa Island And Flores Back Arc Thrust Based On Gravity Data

Based on the BMKG report on Wednesday, July 29, 2018, at 05.47 WIB, an earthquake with a magnitude of 6.4 SR occurred at the epicenter at a depth of 24 km and was 47 km northeast of the island of Lombok. They are allegedly originating from the Back Arc Thrust Flores, the interaction between the Indo-Australian Plate and the Eurasian plate. This study aims to analyze the subsurface structure of the island of Sumbawa and Flores sea based on the distribution of density values. The analysis was carried out by modeling the subsurface structure based on regional gravity field anomaly data. The data used is secondary data downloaded from the topex.ucsd.edu page 18,400 measuring points. Data processing consists of data correction, separation of anomalies, determination of the Second Vertical Derivative (SVD) value, and 3D and 2D inversion modeling. The data corrections performed are Bouguer correction and terrain correction to produce the total gravity anomaly value. Upward continuation is used to separate regional anomalies and residual anomalies. Analysis of the Second Vertical Derivative (SVD) value was carried out to identify rock contact positions and fault structures. The 3D inversion modeling is done by making a mesh model, and to get a 2D cross-section, six slices are used in the 3D model. The results of the 3D model and 2D cross-section, namely the island of Sumbawa to the Back Arc Thrust zone of Flores, consists of 3 main layers comprised of the upper crust with a density of 2.29 gr/cc - 2.63 gr/cc, the middle crust with a density of 2.64 gr/cc - 2.90 gr/cc, and the lower crust with a density of 2.91 gr/cc - 3.14 gr/cc, and based on the model and SVD value, it shows that the Flores back fault, the reverse fault type, starts at a depth of ± 26 km

Transient Response of the Southern Ocean to Idealized Wind and Thermal Forcing across Different Model Resolutions

AbstractThe Southern Ocean has undergone significant climate-related changes over recent decades, including intensified westerly winds and increased radiative heating. The interplay between wind-driven cooling and radiative warming of the ocean is complex and remains unresolved. In this study, idealized wind and thermal perturbations are analyzed in a global ocean–sea ice model at two horizontal resolutions: nominally, 1° and 0.1°. The sea surface temperature (SST) response shows a clear transition from a wind-driven cooling phase to a warming phase. This warming transition is largely attributed to meridional and vertical Ekman heat advection, which are both sensitive to model resolution due to the model-dependent components of temperature gradients. At higher model resolution, due to a more accurate representation of near-surface vertical temperature inversion and upward Ekman heat advection around Antarctica, the anomalous SST warming is stronger and develops earlier. The mixed layer depth at midlatitudes initially increases due to a wind-driven increase in Ekman transport of cold dense surface water northward, but then decreases when the thermal forcing drives enhanced surface stratification; both responses are more sensitive at lower model resolution. With the wind intensification, the residual overturning circulation increases less in the 0.1° case because of the adequately resolved eddy compensation. Ocean heat subduction penetrates along more tilted isopycnals in the 1° case, but it orients to follow isopycnal layers in the 0.1° case. These findings have implications for understanding the ocean response to the combined effects of Southern Hemisphere westerly wind changes and anthropogenic warming.

The thermodynamic structures of the planetary boundary layer dominated by synoptic circulations and the regular effect on air pollution in Beijing

Abstract. To investigate the impacts of multiscale circulations on the planetary boundary layer (PBL), we have carried out the PBL thermodynamic structure field experiment with a Doppler wind profile lidar, a microwave radiometer, and a ceilometer from January 2018 to December 2019 in Beijing. We found that the direct regulatory effect of synoptic circulation worked through transporting and accumulating pollutants in front of mountains in the daytime, while the indirect effect of multiscale circulations worked through coupling mechanisms in the nighttime. The horizontal coupling of different-direction winds produced a severe pollution convergent zone. The vertical coupling of upper environmental winds and lower regional breezes regulated the mixing and diffusion of pollutants by generating dynamic wind shear and advective temperature inversion. We also found that the dominating synoptic circulations led to great differences in PBL thermodynamic structure and pollution. The cyclonic circulation resulted in a typical multilayer PBL characterized by high vertical shear (600 m), temperature inversion (900 m), and an inhomogeneous stratification. Meanwhile, strong regional breezes pushed the pollution convergent zone to the south of Beijing. The southwesterly circulation resulted in a mono-layer PBL characterized by low vertical shear (400 m) and inversion (200 m). The westerly circulation led to a hybrid-structure PBL, and the advective inversion was generated by the vertical shear of zonal winds. Strong environmental winds of southwesterly and westerly circulations pushed the severe-pollution zone to the front of mountains. There was no distinct PBL structure under the anticyclone circulation. The study systematically revealed the appreciable effects of synoptic and regional circulations on PBL structure and air quality, which enriched the prediction theory of atmospheric pollution in the complex terrain.

Gemini/GMOS optical transmission spectroscopy of WASP-121b: signs of variability in an ultra-hot Jupiter?

ABSTRACT We present ground-based, spectroscopic observations of two transits of the ultra-hot Jupiter WASP-121b covering the wavelength range ≈500–950 nm using Gemini/GMOS. We use a Gaussian process framework to model instrumental systematics in the light curves, and also demonstrate the use of the more generalized Student’s-T process to verify our results. We find that our measured transmission spectrum, whilst showing overall agreement, is slightly discrepant with results obtained using HST/STIS, particularly for wavelengths shortwards of ≈650 nm. In contrast to the STIS results, we find evidence for an increasing bluewards slope and little evidence for absorption from either TiO or VO in our retrieval, in agreement with a number of recent studies performed at high-resolution. We suggest that this might point to some other absorbers, particularly some combination of recently detected atomic metals, in addition to scattering by hazes, being responsible for the excess optical absorption and observed vertical thermal inversion. Our results are also broadly consistent with previous ground-based photometry and 3D GCM predictions, however, these assumed different chemistry to our retrievals. In addition, we show that the GMOS observations are repeatable over short periods (days), similar to the HST/STIS observations. Their difference over longer periods (months) could well be the result of temporal variability in the atmospheric properties (i.e. weather) as predicted by theoretical models of ultra-hot Jupiters; however, more mundane explanations such as instrumental systematics and stellar activity cannot be fully ruled out, and we encourage future observations to explore this possibility.