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Observed impact of the GNSS clock data rate on Radio Occultation bending angles for Sentinel-6A and COSMIC-2
Sebastiano Padovan, Axel Von Engeln, Saverio Paolella, Yago Andres, Chad R. Galley, Riccardo Notarpietro, Veronica Rivas Boscán, Francisco Sancho, Francisco Martin Alemany, Nicolas Morew, and Christian Marquardt
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2024-80,2024
Preprint under review for AMT (discussion: open, 0 comments)
Radio Occultation (RO) measurements are an important contribution to numerical weather predictions and long-term climate studies. Using more than a hundred thousand occultations recorded by instruments onboard the Sentinel-6A and Cosmic-2 satellites, this work studies the effects of the clock data rate of the Global Navigation Satellite System on the RO data quality. GLONASS occultations benefit of high-rate clock data (1 second), GPS occultation have high quality already at 30 seconds.

JAXA Level 2 cloud and precipitation microphysics retrievals based on EarthCARE CPR, ATLID and MSI
Kaori Sato, Hajime Okamoto, Tomoaki Nishizawa, Yoshitaka Jin, Takashi Nakajima, Minrui Wang, Masaki Satoh, Woosub Roh, Hiroshi Ishimoto, and Rei Kudo
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2024-99,2024
Preprint under review for AMT (discussion: open, 0 comments)
This study introduces the JAXA EarthCARE L2 cloud product using satellite observations and simulated EarthCARE data. The outputs from the product feature a 3D global view of the dominant ice habit categories and corresponding microphysics. Habit and size distribution transitions from cloud to precipitation will be quantified by the L2 cloud algorithms. With Doppler data, the products can be beneficial for further understanding of the coupling of cloud microphysics, radiation, and dynamics.

Brief communication: SWM – stochastic weather model for precipitation-related hazard assessments using ERA5-Land data
Melody Gwyneth Whitehead and Mark Stephen Bebbington
Nat. Hazards Earth Syst. Sci., 24, 1929–1935, https://doi.org/10.5194/nhess-24-1929-2024, 2024
Precipitation-driven hazards including floods, landslides, and lahars can be catastrophic and difficult to forecast due to high uncertainty around future weather patterns. This work presents a stochastic weather model that produces statistically similar (realistic) rainfall over long time periods at minimal computational cost. These data provide much-needed inputs for hazard simulations to support long-term, time and spatially varying risk assessments.

Abstract

The thermal conductivity of bridgmanite, the primary constituent of the Earth's lower mantle, has been investigated using diamond anvil cells at pressures up to 85 GPa and temperatures up to 3,100 K. We report the results of time-domain optical laser flash heating and X-ray Free Electron Laser heating experiments from a variety of bridgmanite samples with different Al and Fe contents. The results demonstrate that Fe or Fe,Al incorporation in bridgmanite reduces thermal conductivity by about 50% in comparison to end-member MgSiO3 at the pressure-temperature conditions of Earth's lower mantle. The effect of temperature on the thermal conductivity at 28–60 GPa is moderate, well described as k=k300(300/T)a ${k={k}_{300}(300/T)}^{a}$, where a is 0.2–0.5. The results yield thermal conductivity of 7.5–15 W/(m × K) in the thermal boundary layer of the lowermost mantle composed of Fe,Al-bearing bridgmanite.

Abstract

Ground magnetic field variations have been used to investigate ionospheric dynamics for more than a century. They are usually explained in terms of an electric circuit in the ionosphere driven by an electric field, but this is insufficient to explain how magnetic field disturbances are dynamically established. Here we explain and simulate how the ionosphere dynamically responds to magnetospheric forcing and how it leads to magnetic field deformation via Faraday's law. Our approach underscores the causal relationships, treating the magnetic field and velocity as primary variables (the B, v paradigm), whereas the electric field and current are derived, in contrast to the E, j paradigm commonly used in ionospheric physics. The simulation approach presented here could be used as an alternative to existing circuit-based numerical models of magnetosphere-ionosphere coupling.

Abstract

Large constellations of small satellites will significantly increase the number of objects orbiting the Earth. Satellites burn up at the end of service life during reentry, generating aluminum oxides as the main byproduct. These are known catalysts for chlorine activation that depletes ozone in the stratosphere. We present the first atomic-scale molecular dynamics simulation study to resolve the oxidation process of the satellite's aluminum structure during mesospheric reentry, and investigate the ozone depletion potential from aluminum oxides. We find that the demise of a typical 250-kg satellite can generate around 30 kg of aluminum oxide nanoparticles, which may endure for decades in the atmosphere. Aluminum oxide compounds generated by the entire population of satellites reentering the atmosphere in 2022 are estimated at around 17 metric tons. Reentry scenarios involving mega-constellations point to over 360 metric tons of aluminum oxide compounds per year, which can lead to significant ozone depletion.

Abstract

The impact of changes in global temperatures and precipitation on climate distribution remains unclear. Taking the annual global average temperatures and precipitation as the origin, this study determined the climate distribution with the distances of temperature and precipitation from their global averages as the X and Y axes. The results showed that during 1980–2019, the global temperature distribution converged toward the mean (convergence), while the precipitation distribution moved away from the mean (divergence). The combined effects of both led to a convergence in the global climate distribution. During 2025–2100, significant climate convergence is observed under two emission scenarios (SSP245 and SSP585). However, the climate convergence and the area of change in climate type remains insignificant only under SSP126, suggesting that the diversity of the global climate pattern can be maintained under a sustainable emission pathway (SSP126), whereas high emission pathways will lead to greater uniformity in global climate.

Abstract

The balance of processes affecting electron density drives the dynamics of upper-atmospheric electrical events, such as sprites. We examine the detachment of electrons from negatively charged atomic oxygen (O−) via collisions with neutral molecular nitrogen (N2) leading to the formation of nitrous oxide (N2O). Past research posited that this process, even without significant vibrational excitation of N2, strongly impacts the dynamics of sprites. We introduce updated rate coefficients derived from recent experimental measurements which suggest a negligible influence of this reaction on sprite dynamics. Given that previous rates were incompatible with the observed decay of the light emissions from sprite glows, our findings support that glows actually result from electron depletion in sprite columns.

Abstract

Understanding glaciers structural heterogeneity is crucial for assessing their fate. Yet, places where structure changes are strong, such as crevasses fields, are often inaccessible for direct instrumentation. To overcome this limitation, we introduce an innovative technique that transforms seismic sources, here generated by crevasses, into virtual receivers using source-to-receiver spatial reciprocity. We demonstrate that phase interference patterns between well-localized seismic sources can be leveraged to retrieve phase velocity maps using Seismic Michelson Interferometry. The obtained phase velocity exhibits sensitivity to changes in glacier structure, offering insights into the origins of mechanical property changes, with spatial resolution surpassing traditional methods by a factor of five. In particular, we observe sharp variations in phase velocity related to strongly damaged subsurface areas indicating a complex 3-D medium. Applying this method more systematically and in other contexts will enhance our understanding of the structure of glaciers and other seismogenic environments.

Abstract

Air-sea interaction in late boreal winter is studied over the extratropical North Atlantic (NA) during 1960–2020 by examining the relationship between sea-surface temperature (SST) and total turbulent heat flux (THF). The two quantities are positively correlated on interannual timescales over the central-midlatitude and subpolar NA, suggesting the atmosphere on average drives SST and THF variability is independent of SST. On decadal timescales and over the central-midlatitude NA the correlation is negative, suggesting ocean processes on average drive SST and THF variability is sensitive to SST. The correlation is positive over the subpolar NA. There, interannual and decadal THF variability is governed by the North Atlantic Oscillation (NAO). During the major late 20th and early 21st century SST increase in the subpolar NA diminishing oceanic heat loss associated with a weakening NAO was observed. This study suggests that the atmosphere is more sensitive to SST over the central-midlatitude than subpolar NA.

Abstract

Approximately 150 Tg of water vapor and 0.42 Tg of sulfur dioxide were injected directly into the stratosphere by the January 2022 Hunga volcanic eruption, which represents the largest water vapor injection in the satellite era. A comparison of numerical simulations to balloon-borne and satellite observations of the water-rich plume suggests that particle coagulation contributed to the Hunga aerosol's effective dry radius increase from 0.2 μm in February to around 0.4 μm in March. Our model suggests that the stratospheric aerosol effective radius is persistently perturbed for years by moderate and large-magnitude volcanic events, whereas extreme wildfire events show limited impact on the stratospheric background particle size. Our analysis further suggests that both the particle optical efficiency and the aerosols' stratospheric lifetime explain Hunga's unusually large aerosol optical depth per unit of the SO2 injection, as compared with the Pinatubo eruption.

Abstract

With climate change, there will be higher requirements for monitoring storm surges (SSs) in nearshore areas. However, this capability is limited by the sparseness of tide gauge (TG) stations. Establishing and maintaining a permanent, high-spatial coverage, in situ TG network is complex and expensive. Here, we propose a joint modeling method developed from the all-site modeling data-driven framework by importing temporary TGs into coastal regions with insufficient permanent TG stations. The assessments show that this method can significantly optimize the capability of extreme SS monitoring during typhoons and hurricanes. Moreover, the evaluation based on Coupled Model Intercomparison Project Phase 6 data indicates that it will monitor extreme SSs more effectively during 2025–2050 compared with only using existing permanent in situ TGs (reducing root mean square error and absolute mean bias by ∼50%). The joint modeling method provides an applicable and sustainable solution for optimizing the SS monitoring capability in coastal areas.

Abstract

Earthquakes that rupture several faults occur frequently within the shallow lithosphere but are rarely observed for intermediate-depth events (70–300 km). On 29 November 2007, the M w 7.4 Martinique earthquake struck the Lesser Antilles Island Arc near the deep end of the Wadati-Benioff-Zone. The sparse regional seismic network of 2007 previously hampered a detailed examination of this unusually complex event. Here, we combine seismic data from different studies with regional moment tensor inversion results and 3D full-waveform modeling. We show that the earthquake is a doublet consisting of dip-slip and strike-slip motion along two oblique structures, both activated under extensional stress along the strike of the slab. Comparison with tectonic reconstructions suggests that the earthquake ruptured along a re-activated ridge-transform segment of the subducted Proto-Caribbean spreading ridge. The unprecedented resolution of the source process highlights the influence of pre-existing structures on localizing slab deformation also at intermediate-depth.

Abstract

This study investigates the responses of the urban atmospheric thermal environment to two distinct heat waves in Hefei, China, and explores potential changes associated with future urban expansion. During the Event 1, characterized by clear and dry conditions, the western Pacific subtropical high limits water vapor influx, resulting in a significant cooling effect in rural area due to higher surface latent heat flux. The urban heat island (UHI) intensity, calculated using surface temperature and 2-m temperature, reaches 5.2°C and 1.7°C during the Event 1, respectively. Although Event 2, characterized by cloudy and humid conditions, exhibits weaker UHI and urban dry island effects, it remains highly unfavorable for human comfort. During distinct heat waves, the vertical extent of the warming effect induced by future urban expansion varies, which can be attributed to environmental factors, such as atmospheric stability and near-surface wind speed.

Abstract

Anomalous tropical longwave cloud-radiative heating of the atmosphere is generated when convective precipitation occurs, which plays an important role in the dynamics of tropical disturbances. Defining the observed cloud-radiative feedback as the reduction of top-of-atmosphere longwave radiative cooling per unit precipitation, the feedback magnitudes are sensitive to the observed precipitation data set used when comparing two versions of Global Precipitation Climatology Project, version 1.3 (GPCPv1.3) and the newer version 3.2 (GPCPv3.2). GPCPv3.2 contains larger magnitudes and variance of daily precipitation, which yields a weaker cloud-radiative feedback in tropical disturbances at all frequencies and zonal wavenumbers. Weaker cloud-radiative feedbacks occur in GPCPv3.2 at shorter zonal lengths on intraseasonal timescales, which implies a preferential growth at planetary scales for the Madden-Julian oscillation. Phase relationships between precipitation, radiative heating, and other thermodynamic variables in eastward-propagating gravity waves also change with the updated GPCPv3.2.

Abstract

This study uses precipitation oxygen isotopes (δ18Op) to examine key dynamics that deliver moisture to the southern slope of central Himalayas over different seasons. Results show that the majority of pre-monsoon δ18Op values are relatively high and controlled by the westerlies and local moisture. However, some abnormally low δ18Op values coincide with higher precipitation amounts during the pre-monsoon season due to moisture driven northwards from the Bay of Bengal and Arabian Sea to central Himalayas by anomalous circulations (quasi-anticyclone, anticyclone, or/and westerlies trough). The size and location of the quasi-anticyclone also influences the magnitude of the δ18Op decrease. In comparison, the monsoon δ18Op values are lower due to the combined effects of the Indian summer monsoon and convection. Our findings indicate that researchers need to consider the signals of abnormally low δ18Op values during the pre-monsoon season when attempting to interpret ice core and tree-ring records from central Himalayas.

Abstract

We have analyzed Electrostatic Electron Cyclotron Harmonic (ECH) waves observed using interferometry observation mode performed by the Arase satellite to estimate low-energy electron temperatures. Interferometry can be used to calculate velocities, but the Arase satellite can only perform interferometry observations in a one-dimensional direction. We proposed a method to estimate the wave vector of the observed ECH waves from the observed electric fields and calculated the phase velocity for each frequency. We determined the particle parameters from the particle detector and the upper hybrid resonance and estimated the unknown low-energy electron temperature from the agreement between the observed ECH dispersion relation and the theoretical dispersion curves. We performed our analysis for six events and found that the low-energy electron temperature in the observed region is on the order of 1 eV.

Abstract

Relativistic electrons in the radiation belts can be transported as a result of wave-particle interactions (WPI) with ultra-low frequency (ULF) waves. Such WPI are often assumed to be diffusive, parametric models for the radial diffusion coefficient often being used to assess the rates of radial transport. However, these WPI transition from initially coherent interactions to the diffusive regime over a finite time, this time depending on the ULF wave power spectral density, and local resonance conditions. Further, in the real system on the timescales of a single storm, interactions with finite discrete modes may be more realistic. Here, we use a particle-tracing model to simulate the dynamics of outer radiation belt electrons in the presence of a finite number of discrete frequency modes. We characterize the point of the onset of diffusion as a transition from separate discrete interactions in terms of wave parameters by using the “two-thirds” overlap criterion (Lichtenberg & Lieberman, 1992, https://doi.org/10.1007/978-1-4757-2184-3), a comparison between the distance between, and the widths of, the electron's primary resonant islands in phase space. Further, we find the particle decorrelation time in our model system with typical parameters to be on the timescale of hours, which only afterward can the system be modeled by one-dimensional radial diffusion. Direct comparison of particle transport rates in our model with previous analytic diffusion coefficient formulations show good agreement at times beyond the decorrelation time. These results are critical for determining the time periods and conditions under which ULF wave radial diffusion theory can be applied.

Abstract

The storm-enhanced density (SED) is a large-scale midlatitude ionospheric electron density enhancement in the local afternoon sector, which exhibits substantial spatial gradients and thus can impose detrimental effects on modern navigation and communication systems, causing potential space weather hazards. This study has identified a comprehensive list of 49 SED events over the continental US and adjacent regions, by examining strong geomagnetic storms occurring between 2000 and 2023. The ground-based Global Navigation Satellite System (GNSS) total electron content and data from a new TEC-based ionospheric data assimilation system were used to analyze the characteristics of SED. For each derived SED events, we have quantified its morphology by employing a Gaussian function to parameterize key characteristics of the SED, such as the plume intensity, central longitude, and half-width. A statistical analysis of SEDs was conducted for the first time to characterize their climatological features. We found that the SED distribution exhibits a higher peak intensity and a narrower width as geomagnetic activity strengthens. The peak intensity of SED has maximum values around the equinoxes in their seasonal distribution. Additionally, we observed a solar cycle dependence in the SED distribution, with more events occurring during the solar maximum and declining phases compared to the solar minimum. SED plumes exhibit a sub-corotation feature with respect to the Earth, characterized by a westward drift speed between 50 and 400 m/s and a duration of 3–10 hr. These information advanced the current understanding of the spatial-temporal variation of SED characteristics.

It could have been much worse: spatial counterfactuals of the July 2021 flood in the Ahr valley, Germany
Sergiy Vorogushyn, Li Han, Heiko Apel, Viet Dung Nguyen, Björn Guse, Xiaoxiang Guan, Oldrich Rakovec, Husain Najafi, Luis Samaniego, and Bruno Merz
Nat. Hazards Earth Syst. Sci. Discuss., https//doi.org/10.5194/nhess-2024-97,2024
Preprint under review for NHESS (discussion: open, 0 comments)
The July 2021 flood in Central Europe was one of the deadliest floods in Europe in the past decades and the most expensive flood in Germany. In this paper we show that the hydrological impact of this event in the Ahr valley could have been even worse if the rainfall footprint trajectory was only slightly different. The presented methodology of spatial counterfactuals generates plausible unprecedented events and helps better prepare for future extreme floods.