Earth and Space Science最新文献

This paper describes the first field deployment of the Far INfrarEd Spectrometer for Surface Emissivity far-infrared Fourier transform spectrometer to an Arctic environment and shows retrievals of the emissivity of ice and snow in the wavenumber range 400–1,200 cm⁻¹ at viewing angles of 35° and 50°. The retrieved ice emissivity shows a variation of 0.05 between the peak value at around 950 cm⁻¹ and the minimum value at around 750 cm⁻¹. The emissivity is also between 0.01 and 0.02 lower for the higher viewing angle. The emissivity of snow is higher and shows less variation with both viewing angle and wavenumber but it is 0.01 less than one below 900 cm⁻¹. This has implications for remote sensing and climate modeling in this wavenumber range as it implies that both the spectral and angular variation of emissivity must be taken into account. The retrieved ice emissivity agrees well with the emissivity modeled using Fresnel equations. The retrieved snow emissivity agrees well with modeled snow emissivity but further independent measurements of the snow physical properties are needed to test the performance of the model in the far infrared.

A mathematical and numerical framework is developed for modeling Earth's magnetic field and optimizing the trajectory of the whole system using geomagnetic observations. The conventional approach is adopted to model Earth's magnetic field in the source-free region via the Gauss coefficient, for which the fast dynamical component for the mantle-induced field in the mantle region is further constrained by the underlying physical laws of magnetic induction. A spectral approach is adopted to represent the total geomagnetic field. It thereafter yields a rapid convergence of the solution and a smooth and stable continuation of the geomagnetic field from the observational points to all space. Central to the mathematical development of this work is an adjoint formulation for optimizing the trajectory of the coupled dynamical system for an observation time window in variable magnetic boundary conditions, partially determined by other components. We demonstrate the effectiveness of our framework by optimizing a representative geomagnetic system comprising the primary and secondary components of the internal geomagnetic field and a simplified external field using a set of synthetic observations and show that all components of the system can be accurately determined in a variety of space weather conditions. We intend to construct the framework to model the geomagnetic field in a broad region from Earth's interior to the magnetosphere and describe the nonlinear nature and the dynamical balance of Earth's magnetic system in different magnetic weather conditions by utilizing a realistic space current model.

We provide trend estimates for total, stratospheric, and tropospheric ozone columns over Reunion (21.1°S, 55.5°E) from 1998 to 2021, using only Système d’Analyze par Observation Zénithale and Southern Hemisphere Additional OZonesonde observations. Trends are derived using Trend-Run, a multiple linear regression model, and a dynamic linear model (DLM) to identify potential turning points. Overall, total ozone exhibits a positive trend (3.0 $��\pm �$ 1.5 DU/decade), with increases in both stratospheric (1.1 $��\pm �$ 1.6 DU/decade) and tropospheric ozone (2.2 $��\pm �$ 1.0 DU/decade). DLM identifies a turning point in stratospheric ozone in 2008, with a clear decrease in stratospheric ozone before this point and an increase afterward. We also determined changes in the lapse rate tropopause (LRT), the subtropical barrier position, and ERA5 wind and geopotential fields during the same period to investigate possible links between mid-tropospheric ozone increase and transport-related perturbations. Although trends in LRT height and temperature are barely significant, they suggest a recent deepening of the troposphere, indicative of climate change. Intensification of the anticyclonic gyre over Southern Africa and a weakening of the Mascarene anticyclone are found. This suggests that, independent of possible changes in ozone precursor emissions over Africa or South America, dynamics are driving increases of ozone and ozone precursors over Reunion from 1998 to 2021. Furthermore, the rate of Reunion's free tropospheric trends exceeds that observed at all other southern hemisphere ozonesonde stations, including those in tropical, subtropical and mid-latitude regions.

The low-Earth orbit Optical Transient Detector (OTD) and Lightning Imaging Sensor (LIS) instruments, spanning 1995–2023, have spatiotemporal patterns within their metadata that are consistent with the South Atlantic Anomaly (SAA). While the SAA had a known influence on these instruments, this study details new variability and impacts. A large volume of radiation-triggered events can cause the First-In First-Out (FIFO) buffer overflow to occur, which temporarily “blinded” LIS and OTD. Patterns of FIFO and the instrument status flags displayed an evolving intensity and areal extent of SAA interference, affecting climatological view-time records. The interference had a strong relationship to the sunspot number with Pearson correlation values of −0.50 and −0.48 (p < 0.0001 for both) for the view-time anomaly and FIFO occurrence, respectively, over the entire record. For the LIS instruments, the size of the affected region was zero in their early respective records then peaked at millions of square kilometers during solar minimum. LIS on the Tropical Rainfall Measuring Mission (TRMM, TLIS) observed a seasonal cycle with the worst interference during the JJA season and least during DJF. All three instruments found a westward drift of the SAA, at 0.54° y⁻¹, 0.22° y⁻¹, and 0.70° y⁻¹ for TLIS, OTD, and International Space Station LIS (ILIS), respectively. However, while both LIS instruments noted a northward drift, OTD had a southward drift. The influence of external factors including the thermosphere, properties of the radiation, orbital characteristics, and hardware degradation remain to be examined to describe the implications for the SAA itself.

Earth's radiation belts are the regions where highly energetic charged particles are trapped by Earth's magnetic field, posing significant risks to the satellites and other space-based technologies. Understanding the dynamics of the radiation belts is critical not only for advancing fundamental plasma physics but also for predicting and mitigating space weather impacts. To assess recent achievements, identify scientific priorities, and foster collaboration, a round-table discussion was hosted by the “System Understanding of Radiation Belt Particle Dynamics through Multi-Spacecraft and Ground-Based Observations and Modeling” focus group at the 2024 Geospace Environmental Modeling Workshop. Bringing together around 60 participants, including many students and early-career scientists (<10 years post Ph.D.), this session explored recent advances, critical open questions, and future directions in radiation belt science and exploration. Participants highlighted significant progress in observations, modeling, and understanding of radiation belt dynamics over the past decade. However, critical challenges remain, including the accurate quantification of source and loss processes, the role of small- and meso-scale processes in radiation belt dynamics, system coupling within the magnetosphere, and the applicability of current knowledge to more active solar and geomagnetic conditions. The critical need for improved observational and modeling capabilities, open science practices, and stronger community collaboration are identified as priorities to drive future advances in radiation belt sciences.

Launched by the European Space Agency in August 2018, the Aeolus satellite utilizes the Atmospheric Laser Doppler Instrument (ALADIN) to achieve the first global direct measurements of wind profiles in the troposphere and lower stratosphere. The observational data provide important support for global weather forecasting, climate monitoring, and atmospheric dynamics research. This study conducts a systematic evaluation of the Aeolus Level-2B (L2B) wind product over Antarctica by comparing it with radiosonde measurements from polar stations and the fifth-generation ECMWF reanalysis data set (ERA5) during the period from 2019 to 2022. Results show that under Rayleigh-clear conditions, Aeolus winds exhibit a correlation of 0.95 with radiosondes, with a bias of −0.03 m/s, a standard deviation (STD) of 4.29 m/s, and a scaled median absolute deviation (SMAD) of 4.78 m/s. Under Mie-cloudy conditions, the correlation is also 0.95, with a bias of +0.45 m/s, STD of 3.70 m/s, and SMAD of 3.98 m/s. Seasonal analysis indicates larger errors during spring and autumn, while the best agreement is found in summer. Overall, Aeolus wind observations over Antarctica show good consistency with radiosondes, meet ESA mission performance requirements, and provide reliable support for polar weather prediction and climate research.

The annular solar eclipse of 21 June 2020, provided a valuable opportunity to examine the ionospheric response to celestial events. This study analyzes variations in Vertical Total electron content (VTEC) over the equatorial region using data from the UQRG Global Ionospheric Map (GIM), ground-based GPS-TEC measurements, and equatorial electrojet (EEJ) strength from magnetometers near the eclipse path. Significant VTEC reductions were observed during the eclipse. The early decline began in East Africa and South Asia during the morning hours, while in the Western Pacific region, the reduction occurred in the late afternoon, coinciding with the onset of the eclipse. Around local noon, a delayed decrease was detected at stations located in Southeast and East Asia. 22%–53% VTEC reduction was recorded during the eclipse's main phase, with effects persisting from 35 min to over 8 hr post-eclipse. Post-eclipse variations in dusk sector suggest local electrodynamical effects. The study found no significant impact on EEJ strength between $��130�°�$E to $��144�°�$E, and no substantial counter equatorial electrojet was detected. Conducted during the monsoon season and the longest day of the year, observed VTEC reductions likely result from eclipse-induced pressure changes and cooling effects. GIM visualizations showed that dVTEC% decreased by up to $��\sim �$40% globally. The findings indicate that VTEC decreases are not strongly correlated with obscuration percentage, highlighting complexity of ionospheric responses. This study enhances understanding of eclipse-driven ionospheric variability, emphasizing the role of photoionization, recombination, geographic location, and local time, with implications for space weather forecasting and ionospheric modeling.

Magmatic intrusions in rifted continental margins play a critical role in shaping structural evolution, yet their geometry and emplacement mechanisms remain poorly constrained in salt-influenced terrains. The Moroccan Central High Atlas, a segment of the Atlas fold-and-thrust belt, hosts extensive Middle Jurassic to Early Cretaceous intrusions that interact intricately with pre-existing rift structures and evaporite-rich stratigraphy. Yet, their deep subsurface architecture remains poorly resolved due to limited high-resolution imaging. Here, we integrate legacy aeromagnetic and gravity data with modern 2D forward modelling and 3D inversion to resolve the spatial distribution, depth extent, and structural controls of magmatic bodies beneath the Central High Atlas. Our results reveal steeply dipping, dyke-like intrusions aligned with ENE–WSW-trending inherited faults, indicating tectonic inheritance strongly influenced magmatic plumbing. We demonstrate that ascending magmas exploited pre-existing tectonic fabrics, driving salt mobilization and contributing to the growth of diapiric structures. These findings provide the first crustal-scale geophysical image of subsurface intrusions in this region, establishing a genetic link between salt tectonics, magma emplacement, and structural inheritance. Importantly, this is the first 3D crustal-scale geophysical reconstruction of Jurassic magmatic plumbing in the Atlas, revealing their role in diapirism and regional uplift.

Ocean surface wave climates are shaped by both atmospheric forcing and underlying ocean conditions. Variability in open-ocean wave heights subsequently reflects complex interactions occurring across a broad range of spatial and temporal scales. Many of the processes driving this variability take place at small spatial scales that have been previously poorly resolved by sparse altimetry observations and coarse global wave models. The Surface Water and Ocean Topography (SWOT) mission offers a new opportunity to observe variability at these scales with unprecedented two-dimensional measurements of significant wave height (SWH) from the Ka-band radar interferometer (KaRIn). In this study, we evaluate the accuracy of SWOT's KaRIn SWH estimates at an open-ocean calibration site off Central California by comparing them to in situ wave measurements from a closely spaced array of buoys. SWOT KaRIn SWH measurements are validated at the calibration site with high fidelity and perform consistently in additional comparison to a network of coastal wave buoys. The centered root-mean-square error ranges from 0.10 to 0.17 m across the various data sets and product versions, with correlation coefficients exceeding 0.98. Additionally we show that SWOT is capable of accurately resolving gradients in wave conditions over short spatial scales (10–90 km), and the high resolution two-dimensional KaRIn observations better represents spatial variability in SWH than either traditional altimetry or coarse-grid operational numerical wave models run without currents. Overall, these findings validate SWOT's wide-swath observations as a powerful tool for observing and understanding ocean surface wave conditions and their connection to broader ocean-atmosphere dynamics.

X-band Phased array radars are characterized by high spatial and temporal resolution, but suffer from a range of data quality problems, such as echo voids after the filtering of ground clutter, abnormal radials, radial obstructions and irregular missing radar echoes. This paper proposes a radar echo image restoration model (GCD) based on color correction and detail enhancement of adversarial generative networks with dual-stream encoder-decoder. To overcome the challenge of restoring strong echo regions, a multi-scale Feature Alignment (FA)-based strong echo color correction module is designed to achieve FA between original features and radial obstruction features. Additionally, a Local Detail Enhancement Module is designed to enhance the high-frequency texture information in the strong echo regions. The GCD not only applies to all types of radar PPI images but also significantly reduces the time required for initial data processing compared to traditional methods (Sliding Window Filling method). Specifically, the speedup ratio for single-image testing is 361.28. Addressing the issue of radial obstructions, GCD achieves an improvement of 10.15 in PSNR and a notable decrease of 18.921 dBZ in $��\Delta �$|dBZ|, thereby resolving the problem of false enhancement of meteorological echo edges that occurs with the Sliding Window Filling method. When compared to the base model, GCD further enhances the restoration of strong echoes, with a decrease in $��\Delta �$|dBZ| by 0.654. The method proposed fills the gap in the field of radar data quality control in image processing and promotes the development of artificial intelligence in this area.