Local Time Research Articles

Summer alcohol-related emergency department workload and occupancy in Australasia 2019-2022.

Alcohol is a major public health issue and the ACEM funds regular 'snapshot' surveys of the prevalence of alcohol-related presentations in EDs. The present study uses these data to investigate ED occupancy and alcohol- and methamphetamine-related presentations at the time of the COVID-19 pandemic. Survey-based point prevalence study of EDs in Australia and New Zealand conducted at 02:00 hours local time on the Saturday of the weekend before Christmas in 2019-2022. Primary outcomes were ED occupancy, the number of alcohol-related presentations and methamphetamine-related presentations in each ED at the time of survey. Seventy eight of a possible 152 hospitals answered all four surveys (51%, 95% confidence interval 43-59, individual yearly response rates ranged from 70.5% to 83.3%). The mean number of alcohol-related presentations in EDs at the snapshot time was 4.2 (95% confidence interval 3.2-5.2) in the 2019 survey and 3.8 (3.1-4.6) in 2022 with no significant variation over time. There was also no change in methamphetamine-related presentations which occurred at a lower level. There was a major increase in reported total ED occupancy - from 31.4 to 43.5 in Australia (P < 0.0001, paired t test) and from 22.8 to 38.7 in New Zealand (P = 0.0001). Subgroup analysis showed that both the number being treated and the number waiting to be seen increased, with little change in the number in observation units. The present study demonstrates that the COVID-19 pandemic did not affect summer alcohol-related ED presentations in Australasia but was associated with an unsustainable increase in ED crowding.

Rainband‐Occurrence Probability in Northern Hemisphere Tropical Cyclones by Synthetic Aperture Radar Imagery

AbstractRainbands are essential to tropical cyclones (TCs), significantly affecting TC structure and intensity change. High‐resolution synthetic aperture radar (SAR) imagery can capture the footprints of rainbands caused by rain‐induced sea surface roughness modification. Using 464 SAR TC images, we investigated the rainband‐occurrence probability of TCs under different hemispheres, local times (LTs), intensities, and ocean basins. Results show that the rainband‐occurrence probability is highest in the downshear‐left quadrant for Northern Hemisphere TCs (downshear‐right quadrant for Southern Hemisphere TCs). For Northern Hemisphere TCs, the rainband‐occurrence probability is overall higher in the early morning (LT), and the peak region of rainband‐occurrence probability appears farther from the TC center in the evening (LT). Compared with weak TCs, the rainband‐occurrence probability becomes higher for strong TCs in the Northern Hemisphere. Furthermore, TCs have a higher rainband‐occurrence probability in the Northwest Pacific than in the North Atlantic and Northeast Pacific.

A NOVEL MODEL FOR THE RELATIONSHIP BETWEEN THE HEALING TIME OF THE INERT FILM AND THE INCUBATION PERIOD OF LOCALIZED CORROSION

A model for the relationship between the healing time of the scratched diamond-like carbon (DLC) film and the localized corrosion incubation period of metal was established. Based on model calculations combined with experimental results, the scratched DLC film on 13Cr stainless steel was able to heal within 10–16[Formula: see text]h in NaCl solution with an adsorbent-type corrosion inhibitor. However, the localized corrosion incubation time was 30–40[Formula: see text]h. Healing of the scratched DLC film can be completed before localized corrosion occurs. This model provides a theoretical reference for the scratch-repassivation of inert films in corrosion inhibitors solutions.

The electron density at the midpoint of the plasmapause

The high density plasmasphere in the magnetosphere is often separated from a lower density region outside of the plasmasphere, called the plasmatrough, by a sharp gradient in electron density called the plasmapause. Here we use plasmapause events identified from electron density data from the ISEE, CRRES, Polar, and IMAGE missions, and the nonlinear genetic algorithm TuringBot, to find models for the electron density at the midpoint of the plasmapause, ne,pp. A good model for ne,pp should include dependence on L, which is the strongest dependence. But models can be improved by including weaker dependencies on the magnetic local time, MLT, the solar EUV index F10.7, and geomagnetic activity as indicated by averages of Kp and AE. The most complicated model that we present predicts ne,pp within a factor of 1.64, and is within the range of observed plasmapause densities for about 96% of our events. These models can be useful for separating plasma populations into plasmasphere-like and plasmatrough-like populations. We also make available our database of electron density measurements categorized into various populations.

Identification of NINJ1 as a novel prognostic predictor for retroperitoneal liposarcoma

BackgroundRetroperitoneal liposarcoma (RPLS) is known for its propensity for local recurrence and short survival time. We aimed to identify a credible and specific prognostic biomarker for RPLS.MethodsCases from The Cancer Genome Atlas (TCGA) sarcoma dataset were included as the training group. Co-expression modules were constructed using weighted gene co-expression network analysis (WGCNA) to explore associations between modules and survival. Survival analysis of hub genes was performed using the Kaplan–Meier method. In addition, independent external validation was performed on a cohort of 135 Chinese RPLS patients from the REtroperitoneal SArcoma Registry (RESAR) study (NCT03838718).ResultsA total of 19 co-expression modules were constructed based on the expression levels of 26,497 RNAs in the TCGA cohort. Among these modules, the green module exhibited a positive correlation with overall survival (OS, p = 0.10) and disease-free survival (DFS, p = 0.06). Gene set enrichment analysis showed that the green module was associated with endocytosis and soft-tissue sarcomas. Survival analysis demonstrated that NINJ1, a hub gene within the green module, was positively associated with OS (p = 0.019) in the TCGA cohort. Moreover, in the validation cohort, patients with higher NINJ1 expression levels displayed a higher probability of survival for both OS (p = 0.023) and DFS (p = 0.012). Multivariable Cox analysis further confirmed the independent prognostic significance of NINJ1.ConclusionsWe here provide a foundation for the establishment of a consensus prognostic biomarker for RPLS, which should not only facilitate medical treatment but also guide the development of novel targeted drugs.

The Signature of Sporadic E of an Equatorial Ionosphere of the Low Latitude Region

Sporadic E is usually referred to as the large unpredictable formation of regions of very high electron density in the E region as one of the anomalies that is present in the equatorial region. This work studies the variability of sporadic E in the region with respect to the propagation of low frequency communication and impact on the equatorial region during the occurrence of this anomaly. Hourly data for the year 2010, a year of low solar activity obtained in-situ from a Digisonde Portable Sounder (DPS-4) from the African sector, Ilorin, Nigeria (8.5oN, 4.5oE, -2.96 dip) and the Southern American sector online at Jicamarca, Peru (12 oS, 76.8 oW, 0.74 dip) and Fortaleza, Brazil (3 oS, 38 oW, -7.03dip) were used for this study. The result obtained shows that sporadic E is usually observed at the region during the daytime and early evening (0600- 1700 local time) and is more prevalent during solstice months. Two types of sporadic E were observed in the region: blanket and transparent sporadic E. 12% of the transparent sporadic E was observed during the March equinox while 9% of blanket sporadic E was observed during this period; September equinox shows 15% of transparent and 7% blanket sporadic E respectively, while June solstice has 21% transparent and 7% blanket sporadic E. During the December solstices, 14% transparent and 7% blanket sporadic E was observed. During the March equinox, the blanket sporadic E was observed around 0200 hour local time, and that of the transparent sporadic E at about 1000 hour local time. Observation during the September equinox shows that it occurs around 1100 hour and 0200 hour respectively. It was observed that there is no correlation between sporadic E and geomagnetic storm. Sporadic E has been observed to be one of the anomalies that are responsible for the scintillation and scattering of the lower frequency signal in the said region when present.

Clinical implications of DNA methylation-based integrated classification of histologically defined grade 2 meningiomas

The combination of DNA methylation analysis with histopathological and genetic features allows for a more accurate risk stratification and classification of meningiomas. Nevertheless, the implications of this classification for patients with grade 2 meningiomas, a particularly heterogeneous tumor entity, are only partially understood. We correlate the outcomes of histopathologically confirmed grade 2 meningioma with an integrated molecular-morphologic risk stratification and determine its clinical implications. Grade 2 meningioma patients treated at our institution were re-classified using an integrated risk stratification involving DNA methylation array-based data, copy number assessment and TERT promoter mutation analyses. Grade 2 meningioma cases according to the WHO 2021 criteria treated between 2007 and 2021 (n = 100) were retrospectively analyzed. The median clinical and radiographic follow-up periods were 59.8 and 54.4 months. A total of 38 recurrences and 17 deaths were observed. The local control rates of the entire cohort after 2-, 4-, and 6-years were 84.3%, 68.5%, and 50.8%, with a median local control time of 77.2 months. The distribution of the integrated risk groups were as follows: 31 low, 54 intermediate, and 15 high risk cases. In the multivariable Cox regression analysis, integrated risk groups were significantly associated with the risk of local recurrence (hazard ratio (HR) intermediate: 9.91, HR high-risk: 7.29, p < 0.01). Gross total resections decreased the risk of local tumor progression (HR gross total resection: 0.19, p < 0.01). The comparison of 1p status and integrated risk groups (low vs. intermediate/high) revealed nearly identical local control rates within their respective subgroups. In summary, only around 50% of WHO 2021 grade 2 meningiomas have an intermediate risk profile. Integrated molecular risk stratification is crucial to guide the management of patients with grade 2 tumors and should be routinely applied to avoid over- and undertreatment, especially concerning the use of adjuvant radiotherapy.

Nighttime ozone excess days and the associated meteorological conditions in the North China Plain from 2015 to 2022

We examined the spatial and temporal variations of nighttime ozone (O3) excess days (NOEDs) in the North China Plain (NCP) during 2015–2022 by using the observed O3 concentrations from the China National Environmental Monitoring Center network. The NOEDs were defined as those with any 1-h average O3 concentration at night (20:00 to 06:00 local time) exceeding 200 μg m−3. The observations showed that the annual frequencies of NOEDs averaged over the 57 cities in the NCP were 1.56, 1.72, 6.23, 6.53, 8.84, 5.93, 5.07, and 6.86 days in 2015, 2016, 2017, 2018, 2019, 2020, 2021, and 2022, respectively, with a linear increasing trend of 0.66 d y−1. Using the K-means clustering method, two typical regional NOEDs types in the NCP were identified. Type1 had the highest frequencies of NOEDs in the southwest of NCP, while Type2 had the highest frequencies in the central NCP region. These two types contributed to 53.5% and 46.5% of the regional NOEDs in NCP, respectively. Compared with the regional non-NOEDs (with nighttime O3 did not exceed but daytime O3 exceeded O3 air quality standard), both Type1 and Type2 NOEDs generally had higher temperature, lower relative humidity, and higher planetary boundary height in both afternoon and night, favoring the production and accumulation of O3 in the afternoon as well as the persistent high O3 at night. Corresponding weather patterns were also identified. These results have important implications for emission control strategies during NOEDs. Emission control measures can be applied once the dominant circulation patterns have been predicted.

The assessment of chlorophyll-a retrieval algorithm and its spatial-temporal distribution using sentinel-2 MSI off the Banjir Kanal Timur River, Semarang, Indonesia

In aquatic ecology, Chlorophyll-a (Chl-a) plays a pivotal role in biogeochemical cycles, as well as a key indicator for the trophic state in the environment. Coastal area of Semarang is known as eutrophic waters. Thus continuous monitoring of Chl-a will be beneficial for the management of the impact of the trophic dynamic in the coastal waters of Semarang. Taking the benefit of the continuous monitoring of satellite measurement, the present study provides the assessment of Chl-a off the Banjir Kanal Timur (BKT) River, Semarang, using the proper remote sensing approach. In this study, algorithms were generated according to bands sensitive to Chl-a scattering properties, using multiple regression between in-situ Chl-a and Bottom of Atmospheric (BoA) reflectance from Sentinel-2 with 10 m resolution. A total of 43 water samples were collected to build the algorithm and 43 of the water samples were used for validation during the passing time of Sentinel-2 at the equator i.e., on 21 August 2021 at 9.00–11.00 local time. The results show that the performance of the algorithm generated in this study has high accuracy as denoted by the low RMSE, and MAPE, respectively. For the seasonal variation, the highest (lowest) concentration of Chl-a is observed in December (September), with values reaching 11.92 µg/L (7.06 µg/L). The seasonal fluctuation of Chl-a depends on air temperature and sunshine duration. High (low) air temperature and long (short) duration of solar exposure result in increased (decreased) Chl-a off the BKT River. Conversely, the elevated wind velocity only impacts the rise of Chl-a in the region far from the river estuary, which is associated with the mixing process. BKT waters are categorized as eutrophic conditions, with a concentration exceeding 6 µg/L. These algorithms can provide valuable insights into the health and productivity of coastal ecosystems, aiding in their monitoring and management.

Diurnal and seasonal variations of orographic clouds in the Tharsis region with EMM/EXI observations and the Mars Planetary Climate Model

The diurnal and seasonal variations of orographic water ice clouds in the Tharsis region have been investigated with EXI observations for MY 36 and 37. In order to provide context, meteorological fields from the Mars PCM (Mars Planetary Climate Model led by Laboratoire de Météorologie Dynamique Paris, France) have been incorporated. These fields include water ice column, atmospheric temperature, meteorological winds, water vapor, and dust mixing ratio. The diurnal cycle has been studied for sunlit hours (6 am–6 pm) by sampling data into 5 local time bins. Both the EXI observations and the Mars PCM underscore the significant role plays by diurnal thermal tides in controlling the thickness and existence of water ice clouds in the Tharsis region. During Spring and Summer, water ice clouds form in the morning and late-afternoon hours and exhibit greater thickness compared to those that form during the afternoon, primarily due to the influence of thermal tides. During Fall and Winter, water ice clouds are typically observed in the Arsia Mons region, occasionally extending to the Pavonis Mons region. During the Fall and Winter seasons, the clouds that form are mostly thin and have a tendency to develop in the afternoon hours, while the morning hours typically remain cloud-free or exhibit extremely thin clouds. This phenomenon can be attributed to a combination of factors, including the existence of cold temperature zones at higher altitudes formed by the influence of strong trade winds and the impact of diurnal thermal tides. According to the Mars PCM, water ice clouds typically form at altitudes below 25 km during Spring and Summer, whereas during Fall and Winter, cloud formation occurs at altitudes above 25 km.

High-order residual moveout correction with global optimization in local time windows

Residual moveout (RMO) correction is significant for optimizing the common image gathers (CIGs) and migration stacked sections, which is a vital step in seismic data processing. The conventional RMO correction methods flatten the migrated gathers by inverse normal moveout and then pick up the velocity parameters, which require high labor of manual picking with low efficiency. The existing high-order RMO correction methods by scanning technology need a bispectral picking process. To address these issues, we propose a novel high-order RMO correction method based on a crosscorrelation-based objective function with global optimization in local time windows. The selected time windows covering the reflected events in the stacked section are used for parameter estimation. Then the very fast simulated annealing (VFSA) algorithm is used to simultaneously invert the two effective parameters (migration velocity and anellipticity anisotropic parameter) with the local CIGs in the time window, which has relatively high computational efficiency. The Hess model example test results show that the proposed method can effectively deal with the RMO problem in the case of anisotropic media, and the developed high-order RMO correction based on anisotropic assumption significantly improved the imaging performance compared to the conventional isotropic RMO correction methods, especially for steep structures. The application to a real 3D land data set further confirms the effectiveness and practicability of the proposed method.

Characteristics of temporal variability of long-duration bursts of high-energy radiation associated with thunderclouds on the Tibetan plateau

From 1998 to 2017, neutron monitors located at an altitude of 4300 m on the Tibetan plateau detected 127 long-duration bursts of high-energy radiation in association with thunderclouds. These bursts typically lasted for 10–40 min, and 89% of them occurred between 10:00 and 24:00 local time. They were also found to be more likely to occur at night, especially during 18:00–06:00 local time period. The observed diurnal and seasonal variations in burst frequency were consistent with the frequencies of lightning and precipitation on the Tibetan plateau. Based on 19 years of data, the present study suggests that an annual variation in burst frequency has a periodicity of ∼\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sim$$\\end{document} 16 years and a lag of ∼\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sim$$\\end{document} 3 years relative to solar activity.

A Study on Scan Trajectory Based Effective Localization Method Using Mobile Anchor in Wireless Sensor Networks

A Wireless Sensor Network (WSN) is a collection of different nodes working together in a networked fashion in an ordered way. For many applications, sensor location in wireless sensor networks (WSN) is crucial. It is expensive to equip each sensor node with a GPS receiver. Numerous methods, including range-based and range-free methods, have been put forth in the past to determine the locations of sensor nodes that are randomly distributed. The majority of them make use of unique nodes known as anchor nodes, which are thought to be aware of their own positions. These anchor nodes supply the information that other sensors use to calculate their locations. Massive numbers of sensor nodes are used in wireless sensor networks (WSNs) to gather data about the immediate environment. However, this data is useless until the precise location of the data collection points is known. Sensor node localization in wireless sensor networks (WSNs) is important for a number of applications. The current research study develops a path planning technique to apply mobile anchors to the localization systems that are currently in use. The two mobile anchors supported by the effective trajectories, or effective SCAN, is the focus of the proposed research project. To localise the sensor node and transmit data, this method involves setting the mobile anchors to move in the opposite direction. The advantages of this dual movable anchor are demonstrated by the research study in terms of decreased localization time, localization error, and other factors.

Numerical study of shock wave boundary layer interaction flows using a novel turbulence model

This study proposes a novel partial average fluctuation velocity (PAFV) turbulence based on the PAFV and the average strain rate tensor, which is used to calculate the shock wave boundary layer interaction flows, including cascade flow and transonic compressor flow. In order to illustrate the adequacy, the calculation results of several other turbulence models were also compared with PAFV, including k-ω, shear stress transport, SA-neg (negative Spalart-Allmaras), and stress-BSL (ω-based Reynolds stress model). The suitability of the PAFV turbulence model was initially tested by calculating the transonic flow in the L030-4 cascade. Subsequently, numerical computations were performed for the 3D (three-dimensional) National Aeronautics and Space Administration Rotor 67 transonic compressor rotor. In the numerical simulation, the flow control equations were transformed in a general curvilinear coordinate system for precision enhancement, and the spatial discretization of control equations was executed using the finite difference method. The convection term was processed using the Steger–Warming flux vector splitting method, the diffusion term was discretized using a second-order central difference scheme, and the time derivative term was discretized using the third-order Runge–Kutta method. A parallel computing strategy with multi-block partitioning was employed to speed up the calculations and facilitate faster convergence alongside a local time step method. All numerical computation procedures were written in Python, revealing the following: (1) The PAFV turbulence model aptly simulates the transonic flow within the cascade channel. The shock wave pattern in the cascade channel aligns well with the experimental schlieren images. (2) During the Rotor 67 transonic compressor rotor calculation, the flow–pressure ratio, flow efficiency, and inlet and outlet total temperatures and pressures align well with the experimental data. Furthermore, the resolution of the flow field structure related to the interaction between the tip leakage vortex and channel shock wave is high. (3) The turbulence model uses PAFV as the turbulence velocity scale, thereby suppressing the fluctuation velocity and turbulence viscosity near shock wave areas, preventing excessive turbulence viscosity. Moreover, PAFV inherently exhibits transport properties and anisotropic characteristics, making it well-suited for handling transonic compressor flows.

Joule Heating rate at high-latitudes by Swarm and ground-based observations compared to MHD simulations

We compare Joule Heating rates as derived from ground-based magnetic field and all-sky camera data, from Low Earth Orbit satellite data (ESA Swarm) and from a MHD simulation (GUMICS-5) with each other in a case study of an auroral arc system. The observational estimates of Joule Heating rates provide information on regional scales and with high spatial resolution (10–100 km). Their comparison with global MHD results is conducted for a quiet time interval of a few minutes, just before a magnetic substorm. Analysis of the ground-based observations yields electric field with dominating North-South component pointing towards the arcs and having maxima values in the range 20–35 V/km. Combining these values with Pedersen conductance estimates from optical data (5–10 S) yields Joule Heating rates in the range 2.5–3.5 mW/m2. Swarm electric field measurements are consistent in their direction and intensity with the ground-based estimates. They also show that heating is increased particularly in the region where the conductance is low. The total amount of Joule heating in the area between the Swarm A and C satellite footprints while crossing the all-sky camera field of view is estimated to be 46 MW and the total amount energy dissipation during the 80 s overflight is around 3.6 GJ (1000 kWh). GUMICS-5 estimate of the peak Joule Heating in the magnetic local time sector of the arc system is smaller than that from the ground-based data with a factor of 2.9. Comparisons of GUMICS-5 results with Space Weather Modelling Framework (SWMF), shows that the latter gives on average larger heating rates being thus more consistent with our regional observations. However, both MHD-codes yield smaller Joule Heating rates around the time of the arcs and during the following substorm than the CTIP-e code. CTIP-e has a more detailed description of ionosphere-thermosphere interactions than the MHD-codes and its convection electric field is enhanced with a randomly varying additional component mimicking small scale structures. GUMICS-SWMF comparisons of global Joule Heating patterns in the Northern polar area reveal that the two simulations have significant differences in their spatial distribution of heating rates. Main cause for these deviations is the difference in the derivation of ionospheric Pedersen conductance. Our results emphasize the fact that future estimates of the global energetics in the magnetosphere–ionosphere–thermosphere system require better knowledge on ionospheric conductivities, both by new measurement concepts and by better understanding on the background physics controlling conductivity variations.

Statistical Properties of Exohiss Waves and Associated Scattering Losses of Radiation Belt Electrons

AbstractExohiss waves are a type of structureless whistler‐mode waves that exist in the low density plasmatrough outside the plasmapause and may potentially perturb the motions of electrons in the radiation belt and ring current. Using data from Van Allen Probe A, we analyze the distribution of magnetic power spectral density (PSD) of exohiss waves in different magnetic local time (MLT) and L‐shell regions near the geomagnetic equator. The results reveal that the peak magnetic PSD of exohiss waves is the weakest at MLT = 0–6 and the strongest at MLT = 12–18. The magnetic PSDs of exohiss waves are much lower than those of chorus and hiss waves except for the MLT = 12–18 sector. In addition, we calculated the quasi‐linear bounce‐averaged pitch angle and momentum diffusion coefficients (〈Dαα〉 and 〈Dpp〉) of electrons caused by exohiss waves. The diffusion coefficients are then compared with those caused by chorus and hiss waves. The peak 〈Dαα〉 of electrons driven by exohiss waves becomes stronger as L‐shell increases at all MLTs and is the greatest on the dayside, especially in the sector of MLT = 12–18. Exohiss waves have more significant effect on the loss of radiation belt electrons with specific energy levels related to MLT and L‐shell region compared to chorus and hiss waves. On the other hand, 〈Dpp〉 of electrons caused by exohiss waves is very small, which illustrates that exohiss waves have almost no acceleration effect on electrons.

Non‐Geophysical Interhemispheric Asymmetries in Large Magnetic Field Residuals Between Swarm Observations and Earth Magnetic Field Models During Moderate to Quiet Geomagnetic Conditions

AbstractWe present a statistical study of large magnetic field vector residuals between Swarm observations and the 13th generation International Geomagnetic Reference Field (IGRF‐13) model under quiet to moderate geomagnetic conditions. Since the vast majority of data are taken during these conditions, statistics of these large residuals are important for satellite operation when using IGRF‐13 as reference, as well as for magnetosphere‐ionosphere‐thermosphere studies. Residuals with magnitude of vector differences between observations and model estimations larger than 300 nT under Dst &gt; −50 nT are studied from 2014 to 2020. All large residuals appear in the high‐latitude auroral zone region peaking around 70° (−70°) magnetic latitude (MLAT) in the northern hemisphere (southern hemisphere) with also a secondary occurrence peak just below 80° (−80°) MLAT. However, the two hemispheres show clear asymmetries in the magnetic longitude and magnetic local time distribution where both hemispheres show high concentration of large residuals around the geographic poles. Since polar satellite's orbits give rise to highly biased number of observations around the geographic poles, it results in a decrease in occurrence rate with respect to the total number of measurements. We suggest that the asymmetries of large residuals in the two hemispheres around the geographic pole are not geophysical, but due to satellite orbit bias around the geographic poles and difference between IGRF and observations due to model error and geophysical processes not included in the model. Identifying these biases is helpful to better separate out geophysical electric current signatures from non‐geophysical ones.

Long-term assessment and analysis of the radiometric quality of standard data products for Chinese Gaofen-1/2/6/7 optical remote sensing satellites

The first Chinese Gaofen (GF) remote sensing satellite was launched in August 2013 and has been in orbit for more than 10 years, providing a rich variety of image product data for remote sensing applications in various industries, with other remote sensing satellites of the GF series. To ensure the reliability of the information generated via remote sensing applications, all remote sensing images must undergo systematic quality evaluation. The quality of GF satellites is evaluated almost comprehensively during in-orbit testing at the early stage after launch; however, the remaining evaluations of product quality including geometric or radiometric calibrations are performed only annually. Thus, long-term systematic image quality evaluations are lacking, and the quality level and long-term change trends of the image products are unknown. These deficits have introduced uncertainty in the application of these products. This study aimed to establish a radiometric quality evaluation index framework for GF satellites to comprehensively measure the radiometric quality of GF image products. Multiple types of sample data, such as uniform field, knife-edge target, and radiometric calibration field data with different reflectance features, were acquired globally. Four core indexes, namely, the relative radiometric correction accuracy (RRCA), absolute radiometric correction accuracy (ARCA), modulation transfer function (MTF), and signal-to-noise ratio (SNR), were used to analyze and evaluate the long-term radiometric quality of the images from four GF optical remote sensing satellites: GF1, GF2, GF6, and GF7. The four GF satellites had high SNR and RRCA but low dynamic MTF and variable ARCA for different reflectance features. For example, the average SNRs for the four satellites reached 42.66, 43.91, 44.33, and 47.46 dB; the average RRCA (@root-mean-square errors) values reached 1.6%, 1.0%, 1.6%, and 0.1%; the average MTF values (at Nyquist frequency) of the panchromatic bands were only 0.15, 0.12, 0.07 and 0.04; and the difference in ARCA for different reflectance targets was approximately 10%. In the long time series, the SNRs for each sensor of the four GF satellites were high and stable for high-reflectance features, whereas the RCA and SNR values for low-reflectance features and the MTF of the sensors fluctuated in a cyclic manner. Meanwhile, large dynamic fluctuations and episodic image quality problems occurred at certain local time points, which must be considered during practical applications. The findings presented here will lay a foundation for the in-depth application of GF images.

Lower Band Chorus Wave Scattering Causing the Extensive Morningside Diffuse Auroral Precipitation During Active Geomagnetic Conditions: A Detailed Case Study

AbstractThe diffuse aurora is a natural phenomenon observed over the Earth's polar region. Compared with the nightside diffuse aurora, the brightness of the dayside diffuse aurora (0600–1800 magnetic local time (MLT)) is relatively weak, thus requiring more stringent observation conditions. Therefore, the current understanding of what causes the dayside diffuse aurora is still quite limited. Here, we present an intense morningside diffuse aurora (0600–1000 MLT) event observed on 1 January 2016 during the recovery phase of the substorm, using conjugate observations of wave and particle spectrum from the Radiation Belt Storm Probes and auroral emission from the Special Sensor Ultraviolet Spectrographic Imagers on the Air Force Defense Meteorological Satellite Program (DMSP/SSUSI). We perform calculations of diffusion coefficients and simulations of the electron fluxes for this event. Our results show that the chorus waves are the primary contributors to the formation of the morningside diffuse aurora, with precipitated electron energies ranging from a few keV to tens of keV. The lower band chorus shows significant pitch angle scattering efficiency for electrons with energies from 5 to 20 keV. The upper band chorus waves induce acceleration effects on 1–20 keV electrons. We suggest that the upper band chorus waves accelerate low‐energy electrons to higher energies, enabling them to engage in the scattering process of the lower band chorus waves. Our study makes a contribution to recent research on the formation mechanisms of diffuse aurora and deepens our understanding of wave‐particle interactions leading to dayside electron precipitation.

APPROXIMATE SOLUTION FOR TIME FRACTIONAL NONLINEAR MKDV EQUATION WITHIN LOCAL FRACTIONAL OPERATORS

In this paper, we first propose a method, which is originated from coupling local fractional Yang–Laplace transform with the Daftardar–Gejji–Jafaris method (LFYLTDGJM). The proposed method is successfully applied to solve the local time fractional nonlinear modified Korteweg–de Vries (TFNMKDV) equation. The approximate solution presented here illustrates the efficiency and accuracy of the proposed computational technique to solve fractional nonlinear the partial differential equations involving local fractional operators.