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Enhanced Quantitative Precipitation Estimation (QPE) through the opportunistic use of Ku TV-sat links via a Dual-Channel Procedure
Louise Gelbart, Laurent Barthès, François Mercier-Tigrine, Aymeric Chazottes, and Cecile Mallet
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2024-88,2024
Preprint under review for AMT (discussion: open, 0 comments)
In this paper, we present and evaluate a new method for the quantitative estimation of precipitation from a low-cost sensor. Based on previous work measuring the attenuation of an electromagnetic signal from a broadcast television satellite, we make this approach more accurate so that to be easily deployed and used operationally in areas where rainfall measurements are critical for applications like flood monitoring. In this article, the method is validated in France and applied in Ivory Coast.

Calibration of Hydroxyacetonitrile (HOCH2CN) and Methyl isocyanate (CH3NCO) Isomers using I- Chemical Ionization Mass Spectrometry (CIMS)
Zachary Finewax, Aparajeo Chattopadhyay, J. Andrew Neuman, James Roberts, and James Burkholder
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2024-94,2024
Preprint under review for AMT (discussion: open, 1 comment)
This work provides a comprehensive sensitivity calibration of a chemical ionization instrument commonly used in field measurements for the measurement of the toxic isomers methyl isocyanate and hydroxyacetonitrile that are found in the atmosphere. The results from this work has demonstrated that the hydroyacetonitrile isomer was observed in previous field studies rather than the stated identification of methyl isocyanate.

An open-source refactoring of the Canadian Small Lakes Model for estimates of evaporation from medium-sized reservoirs
M. Graham Clark and Sean K. Carey
Geosci. Model Dev., 17, 4911–4922, https://doi.org/10.5194/gmd-17-4911-2024, 2024
This paper provides validation of the Canadian Small Lakes Model (CSLM) for estimating evaporation rates from reservoirs and a refactoring of the original FORTRAN code into MATLAB and Python, which are now stored in GitHub repositories. Here we provide direct observations of the surface energy exchange obtained with an eddy covariance system to validate the CSLM. There was good agreement between observations and estimations except under specific atmospheric conditions when evaporation is low.

The unicellular NUM v.0.91: A trait-based plankton model evaluated in two contrasting biogeographic provinces
Trine Frisbæk Hansen, Donald Eugene Canfield, Ken Haste Andersen, and Christian Jannik Bjerrum
Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2024-53,2024
Preprint under review for GMD (discussion: open, 0 comments)
We describe and test the size-based NUM model, that define organisms by a single set of parameters, on planktonic unicellular ecosystems in a eutrophic and an oligotrophic site. Results show both sites can be modelled with similar parameters, and a robust performance over a wide range of parameters. The study show that the NUM model is useful for non-experts and applicable for modelling domains with limited ecosystem data. It holds promise for evolutionary scenarios and deep-time climate models.

Implementing detailed nucleation predictions in the Earth system model EC-Earth3.3.4: sulfuric acid–ammonia nucleation
Carl Svenhag, Moa K. Sporre, Tinja Olenius, Daniel Yazgi, Sara M. Blichner, Lars P. Nieradzik, and Pontus Roldin
Geosci. Model Dev., 17, 4923–4942, https://doi.org/10.5194/gmd-17-4923-2024, 2024
Our research shows the importance of modeling new particle formation (NPF) and growth of particles in the atmosphere on a global scale, as they influence the outcomes of clouds and our climate. With the global model EC-Earth3 we show that using a new method for NPF modeling, which includes new detailed processes with NH3 and H2SO4, significantly impacts the number of particles in the air and clouds and changes the radiation balance of the same magnitude as anthropogenic greenhouse emissions.

A parameterization scheme for the floating wind farm in a coupled atmosphere–wave model (COAWST v3.7)
Shaokun Deng, Shengmu Yang, Shengli Chen, Daoyi Chen, Xuefeng Yang, and Shanshan Cui
Geosci. Model Dev., 17, 4891–4909, https://doi.org/10.5194/gmd-17-4891-2024, 2024
Global offshore wind power development is moving from offshore to deeper waters, where floating offshore wind turbines have an advantage over bottom-fixed turbines. However, current wind farm parameterization schemes in mesoscale models are not applicable to floating turbines. We propose a floating wind farm parameterization scheme that accounts for the attenuation of the significant wave height by floating turbines. The results indicate that it has a significant effect on the power output.

Abstract

The mesoscale dynamics of a record-breaking Atmospheric River (AR) that impacted the Middle East in mid-April 2023 and caused property damage and loss of life are investigated using model, reanalysis and observational data. The high-resolution (2.5 km) simulations revealed the presence of AR rapids, narrow and long convective structures embedded within the AR that generated heavy precipitation (>4 mm hr−1) as they moved at high speeds (>30 m s−1) from northeastern Africa into western Iran. Gravity waves triggered by the complex terrain in Saudi Arabia further intensified their effects. Given the rising frequency of ARs in this region, AR rapids may be even more impactful in a warming climate, and need to be accounted for in reanalysis and numerical models.

Abstract

Observations show that equatorial ionospheric vertical drifts during solar minimum differ from the climatology between late afternoon and midnight. By analyzing WACCM-X simulations, which reproduce this solar cycle dependence, we show that the interplay of the dominant migrating tides, their propagating and in situ forced components, and their solar cycle dependence impact the F-region wind dynamo. In particular, the amplitude and phase of the propagating migrating semidiurnal tide (SW2) in the F-region plays a key role. Under solar minimum conditions, the SW2 tide propagate to and beyond the F-region in the winter hemisphere, and consequently its zonal wind amplitude in the F-region is much stronger than that under solar maximum conditions. Furthermore, its phase shift leads to a strong eastward wind perturbation near local midnight. This in turn drives a F-region dynamo with an equatorial upward drift between 18 and 1 hr local times.

Abstract

The North Anatolian Fault Zone (NAFZ) is a prominent tectonic structure with a significant impact on the observed active deformation in Türkiye. Detailed knowledge of the seismic anisotropy in the crust and mantle along this nascent shear deformation zone provides insights into the kinematics associated with past and present tectonic events. We employed teleseismic earthquakes observed by the Dense Array North Anatolia seismic network to map 3- D variations in crustal and mantle anisotropy in/around the NW segment of the NAFZ. To achieve this, we first performed a harmonic decomposition analysis of P-receiver functions. The results were then used as a priori information to conduct an anisotropic receiver function inversion with the Neighborhood Algorithm that enabled imaging of the actual orientation and geometry of anisotropic structures. SKS splitting measurements are further used to make a comparison between the anisotropic behavior of crustal and mantle structures. Crustal anisotropy parameters estimated in our analyses/models well identify the signature of deformation caused by accumulated strain in the earthquake cycle through the strike of shallow cutting faults in the brittle crust beneath the NAFZ. Diffuse intense anisotropic energy at lower crustal depths was attributed to lattice preferred orientation of crystals or partially molten lenses elongated along the shear direction. Strong harmonic energy variations beneath the northern part of the Istanbul Zone likely reflect imprints of LPO-originated frozen fabric at shallow depths (0–20 km) associated with the palaeotectonic Odessa Shelf, Intra-Pontide Suture Zones or remnants of the Tethys Ocean.

Abstract

Understanding the dynamics of sulfur dioxide (SO2) degassing is of primary importance for tracking temporal variations in volcanic activity. Here we introduce the novel “disk method,” which aims at estimating the daily volcanic SO2 mass flux from satellite images (such as those provided by Sentinel-5P/TROPOspheric Monitoring Instrument [TROPOMI]). The method calculates a “proto-flux” using a regression, as a function of distance, of SO2 mass integrated in a series of nested circular domains centered on a volcano. After regression, a single multiplication by plume speed suffices to deduce the SO2 mass flux, without requiring a subsequent regression. This way, a range of plume speed and plume altitude scenarios can be easily explored. Noise level in the image is simultaneously evaluated by the regression, which allows for estimating posterior uncertainties on SO2 flux and improving the level of detection for weak sources in noisy environments. A statistical test is also introduced to automatically detect occurrences of volcanic degassing, lowering the risk of false positives. Application to multi-year time-series at Etna (2021) and Piton de la Fournaise (2021–2023) demonstrates (a) a reliable quantification of SO2 emissions across a broad range of degassing styles (from passive degassing to effusive or paroxysmal events), and (b) a reasonable day-to-day correlation between SO2 flux and seismic energy. The method is distributed as an open-source software, and is implemented in an interactive web application within the “Volcano Space Observatory Portal,” facilitating near-real-time exploitation of the TROPOMI archive for both volcano monitoring and assessment of volcanic atmospheric hazards.

Abstract

Nowadays, the most successful applications of full-waveform inversion (FWI) involve marine seismic data under acoustic approximations. Elastic FWI of land seismic data is still challenging in theory and practice. Here, we propose a full dispersion spectrum inversion method and apply it to seismic data acquired in West Antarctica. Inspired by the conventional surface wave dispersion curve inversion method, we propose to invert the surface wave dispersion spectrum instead of the complicated waveforms. We compare the frequency-velocity, frequency-slowness, and frequency-wavenumber spectra in terms of their ability to resolve dispersion modes and the feasibility of their adjoint updates and conclude that the frequency-slowness spectrum is the best for our inversion objectives. We test four objective functions, subtraction, zero-lag crosscorrelation, optimal transport, and the local-crosscorrelation to quantify the spectrum mismatch and provide the corresponding adjoint source. We then theoretically analyze the convexity of the proposed objective functions and examine their convergence behavior using numerical examples. We also compare the proposed method with the classic FWI method and the traditional surface wave dispersion curve inversion method and discuss the strengths and weaknesses of each method. This technique is employed to evaluate the shallow velocity structures beneath a seismic array stationed in West Antarctica. Our proposed inversion scheme is also useful for more general applications such as imaging the shallow subsurface of the critical zones, like geothermal reservoirs, and CO2 storage sites.

Abstract

Collisionless shock waves are efficient ion accelerators. Previous numerical and observational studies have shown that quasi-parallel (Q ‖) shocks are more effective than quasi-perpendicular (Q ⊥) shocks at generating energetic ions under steady upstream conditions. Here, we use a local, 2D, hybrid particle-in-cell model to investigate how ion acceleration at super-critical Q ⊥ shocks is modulated when tangential discontinuities (TDs) with large magnetic shear are present in the upstream plasma. We show that such TDs can significantly increase the ion acceleration efficiency of 2D Q ⊥ shocks, up to a level comparable to Q ‖ shocks. Using data from the hybrid model and test particle simulations, we show that the enhanced energization is related to the magnetic field change associated with the discontinuity. When shock-reflected ions cross the TD during their upstream gyromotion, the sharp field change causes the ions to propagate further upstream, and gain additional energy from the convection electric field associated with the upstream plasma flow. Our findings illustrate that the presence of upstream discontinuities can lead to bursts of energetic ions, even when they do not trigger the formation of foreshock transients. These results emphasize the importance of time-variable upstream conditions when considering ion energization at shocks.

Abstract

The frictional velocity dependence and healing behavior of subduction fault zones play key roles in the nucleation of stick-slip instabilities at convergent margins. Diagenetic to low-grade metamorphic processes such as pressure solution are proposed to be responsible for the change in frictional properties of fault materials along plate interfaces; pressure solution also likely contributes to the acceleration of healing according to previous studies. Here, we report friction studies for temperatures of 20–100°C and normal stresses from 20 to 125 MPa on samples collected from ancient subduction fault zones, the Lower Mugi and Makimine mélanges of the Cretaceous Shimanto belt. The two mélanges correspond to the updip and downdip limits of the seismogenic zone and include deformation features that indicate lower and higher degrees of pressure solution. Our data show that the Lower Mugi mélange exhibits velocity-weakening to velocity-neutral frictional behavior under low normal stress and that the Makimine mélange sample shows velocity-strengthening behavior under high normal stress. We suggest that mineralogical changes due to diagenesis and metamorphism influence fault slip behavior. We measure frictional healing in slide-hold-slide experiments for the Lower Mugi mélange sample and document the role of pressure solution in fault healing. Our results show that frictional healing increases at higher temperatures. The microstructures related to pressure solution found in the post-experimental gouges support the idea that the enhanced healing is related to pressure solution.

Abstract

This work evaluates glacial dust as a source of sediment, and associated iron (Fe), to the Fe-limited Gulf of Alaska (GoA). A reanalysis of GoA sediment data, using rare earth elements and thorium as provenance tracers, suggests a flux to the ocean surface of Copper River (AK) glacial dust, and associated Fe, that is comparable to the flux of dust from Asia, at least 1,000 km from the narrow mountain valley glacial dust source area. This work suggests dust from Asia may not be the largest source of Fe to the GoA. Dust models fail to accurately simulate this glacial dust transport because their coarse resolution underestimates wind speeds, and the dust flux. This work suggests that glacial dust fluxes may have been important in the geologic past (e.g., the last glacial maximum) from locations where there was more extensive coverage by glaciers than at present.

Abstract

Pyroclastic density currents (PDCs) are density-stratified along their vertical axis, with the near-bed portion being denser than the upper portion, resulting from particle settling and ambient air entrainment at current margins. Whereas vertical density stratification likely influences mixing, sedimentation, and buoyancy of PDCs, many depth-averaged models of PDC dynamics assume currents are well-mixed. We investigated this discrepancy by performing sub-aqueous laboratory experiments and conducted complementary numerical simulations to interrogate current dynamics at finer scales. Currents with small temperature difference with the ambient fluid become density-stratified during propagation. The dynamics of such currents resemble two-phase flows, in which particles move freely and particle concentration becomes stratified, but fluid density remains constant. Currents with large temperature difference with the ambient fluid, however, do not develop density stratification during propagation, due to current dynamics becoming dominated by the fluid phase and the lessening importance of particles. Currents that develop density stratification do not lift off from the bed within the domain of the setup, whereas poorly stratified currents do lift off, forming a rising plume. Strong density stratification within currents inhibits turbulence production, preventing entrained ambient fluid on current edges from mixing into current interiors. Poorly stratified currents are highly turbulent, have vigorous internal mixing, thereby achieving lift-off. The strongly stratified currents are analogous to PDCs that result from eruption column collapse, maintaining fast velocity, low internal mixing, and high temperature over long distances. The poorly stratified currents are analogous to dilute ash-cloud surges that develop atop basal avalanches, having short runout distances.

Abstract

Space-based observations of the signatures associated with STEVE show how this phenomenon might be closely related to an extreme version of a SAID channel. Measurements show high velocities (>4 km/s), high temperatures (>4,000 K), and very large current density drivers (up to 1 μA/m2). This phenomena happens in a small range of latitudes, less than a degree, but with a large longitudinal span. In this study, we utilize the GEMINI model to simulate an extreme SAID/STEVE. We assume a FAC density coming from the magnetosphere as the main driver, allowing all other parameters to adjust accordingly. We have two main objectives with this work: show how an extreme SAID can have velocity values comparable or larger than the ones measured under STEVE, and to display the limitations and missing physics that arise due to the extreme values of temperature and velocity. Changes had to be made to GEMINI due to the extreme conditions, particularly some neutral-collision frequencies. The importance of the temperature threshold at which some collision frequencies go outside their respective bounds, as well as significance of the energies that would cause inelastic collisions and impact ionization are displayed and discussed. We illustrate complex structures and behaviors, emphasizing the importance of 3D simulations in capturing these phenomena. Longitudinal structure is emphasized, as the channel develops differently depending on MLT. However, these simulations should be viewed as approximations due to the limited observations available to constrain the model inputs and the assumptions made to achieve sensible results.

Abstract

Measuring the temperature changes of the deep ocean will be critical to understanding how the earth system will respond to climate change. In this work, we present a method for measuring the depth-averaged, deep ocean temperature at local (∼3 km) spatial scales using passive estimates of acoustic propagation. These passive acoustic estimates of deep ocean temperature can be used with existing and future passive acoustic monitoring infrastructure to provide complimentary observations of the ocean to in situ measurements, and could be particularly useful in areas of poor ocean observation coverage. Using 8 years of ambient sound data, we demonstrate that the passive estimates agree with global ocean models and measurements by ARGO floats. The rms difference between the HYCOM ocean model is shown to be 0.13°C, and the rms difference between ARGO measurements is shown to be 0.086°C.

Abstract

Aerosol optical depth (AOD) is a vital parameter in atmospheric research. Using observations of the Visible Infrared Imaging Radiometer Suite (VIIRS), onboard Suomi National Polar-orbiting Partnership (Suomi-NPP) and NOAA-20 satellites, National Oceanic and Atmospheric Administration (NOAA) produces near-real time AOD product with high pixel resolution (750 m), wide swath width (3,040 km), and a 16-day repeat cycle. Here we report the evaluation of the NOAA/VIIRS AOD using a comprehensive aerosol data set, derived from a global-scale, multi-seasonal airborne mission, the NASA Atmospheric Tomography Mission (ATom). This data set includes rich physical and chemical information, such as size distributions, chemical compositions, optical properties, and hygroscopicities of major aerosol types, including dust, sea salt, smoke, internally mixed sulfate/nitrate/organics particles (non-smoke), black carbon, etc. Globally, VIIRS AOD (Suomi-NPP and NOAA-20) shows good agreement with the ATom AOD in the moderate to high AOD range (>0.3), with respect to measurement uncertainties (orthogonal distance regression fitting slope: 1.5 ± 0.2 for Suomi-NPP and 1.6 ± 0.5 for NOAA-20; correlation coefficient: 0.85 for Suomi-NPP and 0.73 for NOAA-20). There is a persistent bias in the low AOD range (<0.3) on the order of 0.03, likely reflecting systematic errors on VIIRS and/or the ATom AOD product. Ångström exponent reported by VIIRS shows excellent agreement with ATom results within expected uncertainties. Given the unique insights revealed by the ATom AOD and aerosol property data set, it is desirable to have ATom-like comprehensive payloads in future airborne satellite validation programs.

Abstract

In the past two decades, the central portion of Campi Flegrei caldera has experienced ground uplift up to 15 mm/month, with an increase of rate, magnitude and extent of the seismicity. In this work, we perform multi-scale precise earthquake relocation of the 2014–2024 seismicity, mapping in detail activated fault zones. We relate the geometry, extent, and depth of these zones with up-to-date structural reconstructions of the caldera. The current seismicity is mainly driven by ground-uplift-induced stress concentration on pre-existing, weaker fault zones, some of which identified for the first time. These structures are not only related to the inner caldera and dome resurgence but also to volcano-tectonic events of the last 10 ka. The extent of imaged fault segments suggests they can accommodate ruptures up to a moment magnitude 5.1, significantly increasing seismic hazard in the area.

Abstract

We provide observational evidence that the stability of the stratospheric Polar vortex (PV) is a significant driver of sub-seasonal variability in the thermosphere during geomagnetically quiet times when the PV is anomalously strong or weak. We find strong positive correlations between the Northern Annular Mode (NAM) index and subseasonal (10–90 days) Global Observations of the Limb and Disk (GOLD) O/N2 perturbations at low to mid-northern latitudes, with a largest value of +0.55 at ∼30.0°N when anomalously strong or weak (NAM >2.5 or < −2.1) vortex times are considered. Strong agreement for O/N2 variability and O/N2-NAM correlations is found between GOLD observations and the Whole Atmosphere Community Climate Model with thermosphere-ionosphere eXtension (WACCM-X) simulations, which is then used to delineate the global distribution of O/N2-NAM correlations. We find negative correlations between subseasonal variability in WACCM-X O/N2 and NAM at high northern and southern latitudes (as large as −0.54 at ∼60.0°S during anomalous vortex times). These correlations suggest that PV driven upwelling at low latitudes is accompanied by corresponding downwelling at high latitudes in the lower thermosphere (∼80–120 km), which is confirmed using calculations of residual mean meridional circulation from WACCM-X.