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A Bias Correction Scheme for FY-3E/ HIRAS-II Observation Data Assimilation
Hongtao Chen and Li Guan
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2024-65,2024
Preprint under review for AMT (discussion: open, 0 comments)
In order to correctly assimilate satellite radiance observations in data assimilation systems, the systematic observation biases must be corrected to conform to a Gaussian normal distribution with a mean of 0.In this paper, a two-step bias correction scheme is established based on radiation observations of HIRAS-II (Hyperspectral Infrared Atmospheric Sounder-II) carried on FY-3E.

Harmonizing seismicity information in Central Asian countries: earthquake catalogue and active faults
Valerio Poggi, Stefano Parolai, Natalya Silacheva, Anatoly Ischuk, Kanatbek Abdrakhmatov, Zainalobudin Kobuliev, Vakhitkhan Ismailov, Roman Ibragimov, Japar Karaev, Paola Ceresa, and Paolo Bazzurro
Nat. Hazards Earth Syst. Sci., 24, 2597–2613, https://doi.org/10.5194/nhess-24-2597-2024, 2024
As part of the Strengthening Financial Resilience and Accelerating Risk Reduction in Central Asia (SFRARR) programme, funded by the European Union in collaboration with the World Bank and GFDRR, a regionally consistent probabilistic multi-hazard and multi-asset risk assessment has been developed. This paper describes the preparation of the input datasets (earthquake catalogue and active-fault database) required for the implementation of the probabilistic seismic hazard model.

ZJU-AERO V0.5: an Accurate and Efficient Radar Operator designed for CMA-GFS/MESO with the capability to simulate non-spherical hydrometeors
Hejun Xie, Lei Bi, and Wei Han
Geosci. Model Dev., 17, 5657–5688, https://doi.org/10.5194/gmd-17-5657-2024, 2024
A radar operator plays a crucial role in utilizing radar observations to enhance numerical weather forecasts. However, developing an advanced radar operator is challenging due to various complexities associated with the wave scattering by non-spherical hydrometeors, radar beam propagation, and multiple platforms. In this study, we introduce a novel radar operator named the Accurate and Efficient Radar Operator developed by ZheJiang University (ZJU-AERO) which boasts several unique features.

Abstract

Sea-air methane flux was measured directly by the eddy-covariance method across approximately 60,000 km of Arctic and Antarctic cruises during a number of summers. The Arctic Ocean (north of 60°N, between 20°W and 50°E) and Southern Ocean (south of 50°S, between 70°W and 30°E) are found to be on-shelf sources of atmospheric methane with mean sea-air fluxes of 9.17 ± 2.91 (SEM (standard error of the mean)) μmol m−2 d−1 and 8.98 ± 0.91 μmol m−2 d−1, respectively. Off-shelf, this region of the Arctic Ocean is found to be a source of methane (mean flux of 2.39 ± 0.68 μmol m−2 d−1), while this region of the Southern Ocean is found to be a methane sink (mean flux of −0.77 ± 0.37 μmol m−2 d−1). The highest fluxes observed are found around west Svalbard, South Georgia, and South Shetland Islands and Bransfield Strait; areas with evidence of the presence of methane flares emanating from the seabed. Hence, this study may provide evidence of direct emission of seabed methane to the atmosphere in both the Arctic and Antarctic. Comparing with previous studies, the results of this study may indicate an increase in sea-air flux of methane in areas with seafloor seepage over timescales of several decades. As climate change exacerbates rising water temperatures, continued monitoring of methane release from polar oceans into the future is crucial.

Abstract

The Carpathian belt is one of Europe's major metallogenic provinces, where magmatic ore mineralization is associated with the past subduction environment. The upper crust is mapped for the first time in the Northeast Carpathian Volcanic Arc using magnetotelluric data inversion. The obtained 3-D electrical resistivity model is interpreted in conjunction with geological information and magnetic anomaly data. The model illustrates the deep magmatic plumbing system including kilometer-scale plutonic bodies at a depth of 2–7 km. The model implies that the transport of magma and fluids in the uppermost crust was controlled by pre-existing faults and décollement horizons. Present ore mineralization, mined since historical times, can be attributed to an electrically conductive conduit that is mapped from the surface to a depth of about 30 km. It is suggested that this conduit connected a shallow magmatic chamber to a deep source region in the southeast during late Miocene time. An observed northwest deflection of the deep magmatic conduit at a depth of more than 10 km may explain the spatial gap in the distribution of the Miocene volcanic activity along the Eastern Carpathians.

Abstract

Two solar eclipse events in 2023 appeared to produce considerable enhancements in the thermospheric column density ratio of monatomic oxygen to molecular nitrogen (ΣO/N2) as measured by TIMED GUVI. We quantify potential sources for eclipse-induced ΣO/N2 changes and find that the observed enhancements arise from the ionospheric O+ radiative recombination contribution to the OI 135.6 nm emission from which ΣO/N2 is derived. Variations in the solar Extreme Ultra Violet (EUV) and X-ray spectrum, due to the difference between the disk spectrum and the coronal spectrum, are also considered but shown to have negligible contributions to the ΣO/N2 enhancements. After accounting for the radiative recombination contribution, we constrain the real thermospheric compositional change to the uncertainty level of the measurements of 5%–10%. These results are valuable for the interpretation of eclipse-induced ΣO/N2 changes that will further first-principle model comparisons and lead to a better understanding of the response of the thermosphere to localized variations in solar EUV and X-ray forcing.

Abstract

There are growing concerns about the effect of solar flares on the ionosphere, mainly due to possible deterioration or damage to our communication and navigation satellite systems. On 3 July 2021, and 28 October 2021, there were solar flares (SFs) classified as X1.59 and X1.0, respectively. These two SFs were the only ones of X-class that occurred during the last low solar activity (LSA:2018–2021). Data from magnetometers and Global Positioning System (GPS)—Total Electron Content (TEC) are used to investigate the spatial-temporal electrodynamics of the ionosphere from pole-to-pole in the American sector. Employing ∆H and vertical TEC, along with the ROT (rate of change of VTEC) parameter. Rapidly ∆H disturbances closely follow the X-ray variation and the ∆H valleys and peaks are well-synchronized during the SFs, indicating that they are linked. Major disturbances in the ∆H are noticed in the mid-low-equatorial latitudes. However, minor disturbances were seen at high latitudes. Also, |ROT| is a good indicator of the electron density changes during the SFs, especially when the X-ray intensity rises to the peak.

Science, Volume 385, Issue 6707, July 2024.

Science, Volume 385, Issue 6707, July 2024.

Science, Volume 385, Issue 6707, July 2024.

Science, Volume 385, Issue 6707, July 2024.

Flood occurrence and impact models for socioeconomic applications over Canada and the United States
Manuel Grenier, Mathieu Boudreault, David A. Carozza, Jérémie Boudreault, and Sébastien Raymond
Nat. Hazards Earth Syst. Sci., 24, 2577–2595, https://doi.org/10.5194/nhess-24-2577-2024, 2024
Modelling floods at the street level for large countries like Canada and the United States is difficult and very costly. However, many applications do not necessarily require that level of detail. As a result, we present a flood modelling framework built with artificial intelligence for socioeconomic studies like trend and scenarios analyses. We find for example that an increase of 10 % in average precipitation yields an increase in displaced population of 18 % in Canada and 14 % in the US.

Abstract

We present measurements of 30–700 keV Solar Energetic Electrons (SEEs) near the Moon when within the terrestrial magnetotail by the Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun spacecraft. Despite their detection deep within the tail, the incident flux and spectral shape of these electrons are nearly identical to measurements taken upstream of Earth in the solar wind by the Wind spacecraft; however, their pitch angle distribution is isotropized compared to the more field-aligned distribution upstream. We illustrate that SEEs initially traveling Earthward precipitate onto the lunar far-side, generating extended shadows in the cis-lunar electron distribution. By modeling the dynamics of these electrons, we show that their precipitation patterns on the lunar near-side are comparatively reduced. The non-uniform precipitation and accessibility of potentially hazardous electrons to the Moon's surface are highly relevant in the context of astronaut safety during the planned exploration of the lunar environment.

Abstract

Subsurface gas storage is crucial for achieving a sustainable energy future, as it helps to reduce CO2 emissions and facilitates the provision of renewable energy sources. The confinement effect of the nanopores in caprock induces distinctive thermophysical properties and fluid dynamics. In this paper, we present a multi-scale study to characterize the subsurface transport of CO2, CH4, and H2. A nanoscale-extended volume-translated Cubic-Plus-Association equation of state was developed and incorporated in a field-scale numerical simulation, based on a full reservoir-caprock suite model. Results suggest that in the transition from nanoscale to bulk-scale, gas solubility in water decreases while phase density and interfacial tension increase. For the first time, a power law relationship was identified between the capillary pressure within nanopores and the pore size. Controlled by buoyancy, viscous force and capillary pressure, gases transport vertically and horizontally in reservoir and caprock. H2 has the maximum potential to move upward and the lowest areal sweep efficiency; in short term, CH4 is more prone to upward migration compared to CO2, while in long term, CH4 and CO2 perform comparably. Thicker caprock and larger caprock pore size generally bring greater upward inclination. Gases penetrate the caprock when CH4 is stored with a caprock thickness smaller than 28 m or H2 is stored with a caprock pore size of 2–10 nm or larger than 100 nm. This study sheds light on the fluid properties and dynamics in nanoconfined environment and is expected to contribute to the safe implementation of gigatonne scale subsurface gas storage.

Abstract

Bottom currents play a major role in deep-sea sedimentation, but their significance in the burial of organic carbon is poorly quantified at a global scale. Here we show that Holocene fluxes of organic carbon into the contourite drifts are high, with a global average of 0.09 g cm−2 Kyr−1. At individual drift sites, fluxes are commonly 1–2 orders of magnitude greater than rates in surrounding areas and in global depth-similar zones. These high fluxes of organic carbon into the contourite drifts are due to high rates of sedimentation. Over the past 50 million years, sedimentation rates at the studied contourite drift sites have overall increased, coincident with decreasing atmospheric CO2 and a cooling global climate. Our work suggests that a ramp-up of the bottom-current carbon pump has accelerated removal of CO2 from the atmosphere and oceanic water, thus contributing to the overall global cooling after the Eocene Thermal Maximum.

Abstract

Complex natural fracture networks typically consist of multiple clusters, whose connectivity is rarely quantified. Therefore, for each identified fracture network, we propose a connectivity metric that accounts for individual fracture clusters and their interactions. This metric evaluates contributions from all fracture clusters, considering their relative sizes and interactions among the isolated clusters, which in turn depend on the hydraulic conductance of the interconnecting rock matrix. Furthermore, we investigate how the system connectivity depends on fracture sealing, alterations of central clusters, and cluster linkage. Fracture sealing strongly impacts overall fracture connectivity, with 5 percent of sealed fractures reducing connectivity by 20 percent. The connectivity reduction is small when transitioning the central cluster from the largest to the smallest one. However, the largest cluster significantly contributes to overall connectivity, while the smallest one contributes minimally. Natural fracture networks increase connectivity by linking more clusters, with heterogeneity and anisotropy playing pivotal roles.

What can we learn from global disaster records about multi-hazards and their risk dynamics?
Wiebke S. Jäger, Marleen C. de Ruiter, Timothy Tiggeloven, and Philip J. Ward
Nat. Hazards Earth Syst. Sci. Discuss., https//doi.org/10.5194/nhess-2024-134,2024
Preprint under review for NHESS (discussion: open, 0 comments)
Multiple hazards, occurring at the same time or shortly after one another, can have more extreme impacts than single hazards. We examined the disaster records in the global emergency events database EM-DAT to better understand this phenomenon. We developed a method to identify such multi-hazards and analyzed their reported impacts using statistics. Multi-hazards have accounted for a disproportionate amount of the overall impacts, but there are different patterns in which the impacts compound.

Abstract

Since the 1950s, observations and climate models show an amplification of sea surface temperature (SST) seasonal cycle in response to global warming over most of the global oceans except for the Southern Ocean (SO), however the cause remains poorly understood. In this study, we analyzed observations, ocean reanalysis, and a set of historical and abruptly quadrupled CO2 simulations from the Coupled Model Intercomparison Project Phase 6 archive and found that the weakened SST seasonal cycle over the SO could be mainly attributed to the intensification of summertime westerly winds. Under the historical warming, the intensification of summertime westerly winds over the SO effectively deepens ocean mixed layer and damps surface warming, but this effect is considerably weaker in winter, thus weakening the SST seasonal cycle. This wind-driven mechanism is further supported by our targeted coupled model experiments with the wind intensification effects being removed.

Abstract

Solar-induced fluorescence (SIF) is a proxy of ecosystem photosynthesis that often scales linearly with gross primary productivity (GPP) at the canopy scale. However, the mechanistic relationship between GPP and SIF is still uncertain, especially at smaller temporal and spatial scales. We deployed a ultra-hyperspectral imager over two grassland sites in California throughout a soil moisture dry down. The imager has high spatial resolution that limits mixed pixels, enabling differentiation between plants and leaves within one scene. We find that imager SIF correlates well with diurnal changes in leaf-level physiology and gross primary productivity under well-watered conditions. These relationships deteriorate throughout the dry down event. Our results demonstrate an advancement in SIF imaging with new possibilities in remotely sensing plant canopies from the leaf to the ecosystem. These data can be used to resolve outstanding questions regarding SIF's meaning and usefulness in terrestrial ecosystem monitoring.

Abstract

This study investigates the potential impact of Solar Energetic Particles (SEPs) on the V0 layer of the Venus ionosphere. Electron density profiles obtained from radio occultation experiments conducted by the Venus Express (VEX) and Akatsuki missions were utilized for this purpose. Background data from the Analyzer of Space Plasma and EneRgetic Atoms (ASPERA-4) aboard VEX were used to detect SEP events. Additionally, observations from the Space Environment Monitor (SEM) suite onboard the Geostationary Operational Environmental Satellite (GOES) during alignments of Venus, Earth, and the Sun were also considered. Our findings indicate that while SEPs may contribute to the formation of the V0 layer, they are not the main driving force in the Venusian ionosphere.