Earth and Space Science最新文献

Atmospheric precipitable water vapor (PWV) is a crucial factor affecting precipitation and the atmospheric environment. To quantitatively investigate the spatio-temporal distribution and characteristics of the PWV in Fujian, China, its diurnal and seasonal variations are analyzed based on the global navigation satellite system (GNSS) data from 2010 to 2023, ground meteorological observations, meteorological sounding data and ERA5 data. Moreover, the spatio-temporal characteristics of the monthly PWV are assessed by using the empirical orthogonal function (EOF), the Mann-Kendall test and the sliding t-test. The results indicate that the ground-based GNSS PWV data is able to reveal the distribution and variation of PWV over Fujian. Specifically, the diurnal distribution of the PWV varies remarkably with time, and the PWV in the eastern coastal areas is generally higher than in the western mountainous areas. The seasonal variation characteristics of the PWV are consistent with the atmospheric circulation variations, with the largest amount of PWV in summer, followed by spring, autumn and winter. Moreover, the EOF spatial modes show that the PWV distributions are different in the eastern coastal areas and inland mountainous areas. The oscillation intensity of the PWV strengthens from the northwest to the southeast, and the corresponding time series of the PWV displays apparent seasonal variations. The observed precipitation is inconsistent with the PWV and is more affected by local terrain and thermodynamic conditions. The Mann-Kendall test and the sliding t-test indicate that the PWV over Fujian has not undergone abrupt changes during the past 13 years, but there is a possibility of sudden changes in the future.

The Macau Science Satellites (MSS-1) mission, consisting of twin low earth orbit satellites (Satellite A and B), is the first low-inclination and high-precision geomagnetic surveying satellite project in China. Among the multiple scientific payloads equipped with the scientific satellites, MSS-1 carries a GNSS radio occultation (RO) receiver on Satellite A, and aims to observe the Earth's ionosphere and monitor the space weather especially in the South Atlantic Anomaly (SAA) area. This paper focuses on the ionospheric data of MSS-1 obtained during the first 3 months after its launch, and assesses the RO products as well as initial scintillation measurements. Results show that MSS-1 RO data have very good agreement with contemporary COSMIC-2 and ionosonde observations. The scintillation amplitude indices S4 are comparable with that of COSMIC-2 and well reflect the occurrence rates and distributions of equatorial plasma bubble and sporadic E (Es) in June solstice season. Special attentions are paid to the SAA longitude sector and inspire explorations on the seasonal variations and local-time dependences of ionospheric irregularities.

Oceanic biogeochemistry plays a pivotal role in regulating Earth's climate system by governing the cycling of key elements such as carbon, oxygen, and nutrients. Various metocean processes including wind, tides, currents, waves, and eddies significantly influence the dynamics of this system. In particular, ocean surface waves contribute to this intricate interplay by facilitating the exchange of heat, gas, and momentum between the atmosphere and the ocean. Although wave-coupled effects are substantial, studies on their impacts on oceanic biogeochemistry, particularly on phytoplankton abundance are missing in present-day research. Additionally, wave-coupled effects cannot be disregarded in regions like the Southern Ocean (SO), where wind and waves activities are prominent. Addressing this gap, we incorporated a parameterization of surface wave mixing into a global ocean biogeochemical model to investigate its effects on upper ocean and biogeochemical parameters. Our results show that surface wave mixing has significant impacts on sea surface temperature (SST), mixed layer depth (MLD), and nutrient distribution—key factors that influence phytoplankton growth. Additionally, we observed significant improvements in model biases against the observations. During austral summer, additional mixing from surface waves can significantly lower SST by 0.5°C, deepen MLD by 13 m, and enhance Chlorophyll-a (Chl-a) concentration, an index of phytoplankton population, by 8% in the SO. This observed increase in Chl-a concentration is mainly driven by enhanced dissolved iron levels resulting from wave-induced mixing. Our findings underscore the significance of incorporating surface wave mixing in ocean biogeochemistry studies, an aspect that is currently overlooked.

We present a new inversion scheme for 2D magnetotelluric data. In contrast to established approaches, it is based on a mesh-free formulation of the Quasi-Newton Broyden–Fletcher–Goldfarb–Shanno (BFGS) iteration which uses the cost function gradient to implicitly construct approximations of the Hessian inverse to update the unknown conductivity. We introduce conventional first–order regularization as well as second–order regularization where inversions based on the latter are more appropriate for sparse data and can be read as maximum likelihood estimation of the unknown conductivity. We apply first–order finite element method (FEM) discretizations of the inversion scheme, forward and adjoint problems, where the latter is required for the construction of the cost function gradients. We allow for unstructured first–order triangular meshes supporting an enhanced ground level resolution including topographical features and coarsening at the far field leading to significant reduction in computational costs from using structured mesh. Formulating the inversion iteration in continuous form prior to discretization eliminates bias due to local refinements in the mesh and gives way for computationally efficient sparse matrix techniques in the implementation. A keystone in the new scheme is the multi-grid approximation of the Hessian of the regularizations to construct efficient preconditioning for the inversion iteration. The method is applied to the Commeni4 benchmark and two field data sets. Tests show that for both first and second–order regularization an anisotropic approach is important to address the vast differences in horizontal and vertical spatial scale which in conventional approaches is implicitly introduced through the elongated shape of grid cells.

In the nearshore area, ocean current display intricate complexities due to interactions among tide, river, and coastline, which makes accurate current modeling challenging. Continuous in situ observation with high spatial and temporal resolution helps to better understand the dynamics of these currents. In this study, we used a 10-km long submarine fiber-optic cable with distributed acoustic sensing technology to record seismic signals associated with ocean waves. The current velocity and water depth were obtained from the velocity dispersion using frequency-wave number analysis matched against theoretical ocean wave propagation equations. The results show remarkable agreement with observation of a nearby current meter, confirming the dominance of tidal currents as well as a small-scale residual current. The temporal variation of water depth is consistent with observation by a nearby tidal gauge. This study demonstrates the potential of using submarine fiber-optic cable for long-term, high-resolution, near real-time nearshore current monitoring.

This study presents new glyoxal (CHOCHO) products from the Ozone Monitoring Instrument (OMI) by utilizing updated level 1B irradiance/radiance data (Collection 4) and an updated glyoxal retrieval algorithm. The adoption of Collection 4 contributes to the reduction of artificial signals in differential glyoxal slant column densities (dSCDs) and improved fitting root mean square, and the updated retrieval settings result in fewer negative values of glyoxal dSCDs over oceans and less noisy dSCDs in the South Atlantic Anomaly. On-line calculations of air mass factors consider interactive physical processes between input parameters. To address persistent trends in glyoxal SCDs over the Pacific Ocean that remain despite these updates, a trend correction is implemented. We evaluate the updated OMI glyoxal products using inter-comparisons with GOME-2A/2B glyoxal products. OMI glyoxal products exhibit good spatial and temporal agreement with GOME-2A/2B, with correlation coefficients of 0.75–0.78 globally and 0.84–0.85 over source regions. Small biases are observed in OMI glyoxal vertical column densities, ranging from −0.2 ± 5.7% to 9 ± 3% in low and high glyoxal conditions, respectively, against GOME-2A/2B. These advancements contribute to the reliability and accuracy of OMI glyoxal products, enhancing their utility for atmospheric studies and enabling a 20-year-long data record suitable for climate studies.

Surface thermal inertia derived from satellite imagery offers a valuable tool for remotely mapping the physical structure and water content of planetary regolith. Efforts to quantify thermal inertia using surface temperatures on Earth, however, have consistently yielded large uncertainties and suffered from a lack of reproducibility. Unlike dry or airless bodies, Earth's abundant water and dense atmosphere lead to dynamic thermophysical conditions that are a greater challenge to model than on a world like Mars. In this work, an approach was developed using field experiments to inform and fine-tune a thermophysical model of terrestrial sediment and calculate an inherent thermal inertia value with higher precision and less initial knowledge of the sediment than has previously been achieved remotely on Earth. A thermal inertia derived for a basaltic tephra site in Northern Arizona was replicated within 1% between different field seasons, demonstrating reproducibility. Model-derived values were validated in situ by two different thermophysical field probes to within 8% of the measured mean values. Analog studies such as this hold the promise of improved interpretations of surface materials on Mars, and an accurate thermal model for Earth is the key step to enabling translation between the two worlds.

We investigate the benefits of future quantum accelerometers based on cold atom interferometry (CAI) on current and upcoming satellite gravity mission concepts. These mission concepts include satellite-to-satellite tracking (SST) in a single-pair (GRACE-like) and double-pair constellation as well as satellite gravity gradiometry (SGG, single satellite, GOCE-like). Regarding instruments, four scenarios are considered: current-generation electrostatic (GRACE-, GOCE-like), next-generation electrostatic, conservative hybrid/CAI and optimistic hybrid/CAI. For SST, it is shown that temporal aliasing poses currently the dominating error source in simulated global gravity field solutions independent of the investigated instrument and constellation. To still quantify the advantages of CAI instruments on the gravity functional itself, additional simulations are performed where the impact of temporal aliasing is synthetically reduced. When neglecting temporal aliasing, future accelerometers in conjunction with future ranging instruments can substantially improve the retrieval performance of the Earth's gravity field (depending on instrument and constellation). These simulation results are further investigated regarding possible benefit for hydrological use cases where these improvements can also be observed (when omitting temporal aliasing). For SGG, it is demonstrated that, with realistic instrument assumptions, one is still mostly insensitive to time-variable gravity and not competitive with the SST principle. However, due to the improved instrument sensitivity of quantum gradiometers compared to the GOCE mission, static gravity field solutions can be improved significantly.

The Andrade rheological model is often employed to describe the response of solar system or extra-solar planets to tidal perturbations, especially when their properties are still poorly constrained. While for uniform planets with steady-state Maxwell rheology the analytical form of the Love numbers was established long ago, for the transient Andrade rheology no closed-form solutions have been yet determined, and the planetary response is usually studied either semi-analitically in the frequency domain or numerically in the time domain. Closed-form expressions are potentially important since they could provide insight into the dependence of Love numbers upon the model parameters and the time-scales of the isostatic readjustment of the planet. First, we focus on the Andrade rheological law in 1-D and we obtain a previously unknown explicit form, in the time domain, for the relaxation modulus in terms of the higher Mittag-Leffler transcendental function E_α,β(z) that generalizes the exponential function. Second, we consider the general response of an incompressible planetary model — often referred to as the “Kelvin sphere” — studying the Laplace domain, the frequency domain and the time domain Love numbers by analytical methods. Through a numerical approach, we assess the effect of compressibility on the Love numbers in the Laplace and frequency domains. Furthermore, exploiting the results obtained in the 1-D case, we establish closed-form — although not elementary — expressions of the time domain Love numbers and we discuss the frequency domain response of the Kelvin sphere with Andrade rheology analytically.

In this study, the evolutional features and underlying driving mechanisms of the postmidnight-to-dawn equatorial plasma bubble (EPB) irregularities during the weak geomagnetic activity period on 13 November 2015 were investigated based on the multiple satellite and ground-based observations. By using the coherent scatter radar operating at very high frequency at Fuke (19.5°N, 109.1°E, dip latitude 14.4°N), China, it was found that the freshly developed field-aligned irregularities (FAIs) occurred within the radar's field of view around ∼04:37 LT and sustained for more than 40 min. The remarkable EPB-related density and total electron content (TEC) depletions measured by the satellite and GNSS receivers were also observed, which indicates the persistence of EPB irregularities until ∼06 LT. The significant elevation of bottomside F-layer's virtual height obtained by the Digisonde at Fuke as well as the upward vertical F-layer plasma drifts derived from a nearby Digisonde at Sanya (18.4°N, 109.6°E, dip latitude 13.1°N) both imply the existence of strong eastward perturbation electric fields after local midnight. These findings suggest that the collective effects of eastward overshielding penetration electric field (PEF) resulted from the substorm onset and rapid northward turning of the interplanetary magnetic field (IMF) Bz, surpassed the role of westward undershielding prompt penetration electric field (PPEF) induced by the southward turning of IMF Bz. Thus, the former predominated in modulating the equatorial/low-latitude zonal electric fields and raised the F-layer considerably, which consequently boosted the growth of R-T instability and created the favorable conditions for the postmidnight-to-dawn EPBs development.