An improved model for air–sea exchange of elemental mercury in MITgcm-ECCO v4-Hg: the role of surfactants and waves
Ling Li, Peipei Wu, Peng Zhang, Shaojian Huang, and Yanxu Zhang
Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2024-81,2024
Preprint under review for GMD (discussion: open, 0 comments)
The estimation of Hg0 fluxes is of great uncertainty due to neglecting wave breaking and sea surfactant. Integrating these factors into MITgcm significantly rise Hg0 transfer velocity. The updated model shows increased fluxes in high wind and wave regions and vice versa, enhancing the spatial heterogeneity. It shows a stronger correlation between Hg0 transfer velocity and wind speed. These findings may elucidate the discrepancies in previous estimations and offer insights into global Hg cycling.
A computationally light-weight model for ensemble forecasting of environmental hazard: General TAMSAT-ALERT v1.2.1
Emily Black, John Ellis, and Ross Maidment
Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2024-75,2024
Preprint under review for GMD (discussion: open, 0 comments)
We present General TAMSAT-ALERT: a computationally lightweight and versatile tool for generating ensemble forecasts from time series data. General TAMSAT-ALERT is capable of combining multiple streams of monitoring and forecasting data into probabilistic hazard assessments. As such, it complements existing systems and enhances their utility for actionable hazard assessment.
In a study published in Nature Communications, researchers have documented that persistent millennial-scale Asian winter monsoon (AWM) intensity fluctuations were superimposed on 41-kyr and ~100-kyr orbital variability during both the warmer (higher CO2) late Pliocene and colder (lower CO2) early Pleistocene, in response to both external astronomical forcing and internal climate dynamics.
To preserve the important intertidal areas and salt marshes off our coasts for the future, we need more turbid water. That is one of the striking conclusions from a new study conducted by a Dutch-Chinese team of researchers and published in Nature Geoscience.
U-Plume: automated algorithm for plume detection and source quantification by satellite point-source imagers
Jack H. Bruno, Dylan Jervis, Daniel J. Varon, and Daniel J. Jacob
Atmos. Meas. Tech., 17, 2625–2636, https://doi.org/10.5194/amt-17-2625-2024, 2024
Methane is a potent greenhouse gas and a current high-priority target for short- to mid-term climate change mitigation. Detection of individual methane emitters from space has become possible in recent years, and the volume of data for this task has been rapidly growing, outpacing processing capabilities. We introduce an automated approach, U-Plume, which can detect and quantify emissions from individual methane sources in high-spatial-resolution satellite data.
TROPESS-CrIS CO single-pixel vertical profiles: intercomparisons with MOPITT and model simulations for 2020 western US wildfires
Ming Luo, Helen M. Worden, Robert D. Field, Kostas Tsigaridis, and Gregory S. Elsaesser
Atmos. Meas. Tech., 17, 2611–2624, https://doi.org/10.5194/amt-17-2611-2024, 2024
The TROPESS CrIS single-pixel CO profile retrievals are compared to the MOPITT CO products in steps of adjusting them to the common a priori assumptions. The two data sets are found to agree within 5 %. We also demonstrated and analyzed the proper steps in evaluating GISS ModelE CO simulations using satellite CO retrieval products for the western US wildfire events in September 2020.
An iterative algorithm to simultaneously retrieve aerosol extinction and effective radius profiles using CALIOP
Liang Chang, Jing Li, Jingjing Ren, Changrui Xiong, and Lu Zhang
Atmos. Meas. Tech., 17, 2637–2648, https://doi.org/10.5194/amt-17-2637-2024, 2024
We described a modified lidar inversion algorithm to retrieve aerosol extinction and size distribution simultaneously from two-wavelength elastic lidar measurements. Its major advantage is that the lidar ratio of each layer is determined iteratively by a lidar ratio–Ångström exponent lookup table. The algorithm was applied to the Raman lidar and CALIOP measurements. The retrieved results by our method are in good agreement with those achieved by Raman method.
Abstract
This is the first report of significant energization (up to 7,000 eV) of low-energy He+ ions, which occurred simultaneously with H-band electromagnetic ion cyclotron (EMIC) wave activity, in a direction mostly perpendicular to the ambient magnetic field. The event was detected by the Arase satellite in the dayside plasmatrough region off the magnetic equator on 15 May 2019. The peak energy of the He+ flux enhancements is mostly above 1,000 eV. At some interval, the He+ ions are energized up to ∼7,000 eV. The H-band waves are excited in a frequency band between the local crossover and helium gyrofrequencies and are close to a linear polarization state with weakly left-handed or right-handed polarization. The normal angle of the waves exhibits significant variation between 0° and 80°, indicating a non-parallel propagation. We run a hybrid code with parameters estimated from the Arase observations to examine the He+ energization. The simulations show that cold He+ ions are energized up to more than 1,000 eV, similar to the spacecraft observations. From the analysis of the simulated wave fields and cold plasma motions, we found that the ratio of the wave frequency to He+ gyrofrequency is a primary factor for transverse energization of cold He+ ions. As a consequence of the numerical analysis, we suggest that the significant transverse energization of He+ ions observed by Arase is attributed to H-band EMIC waves excited near the local helium gyrofrequency.
Author(s): Shaan Nagy, Roger Paredes, Jeffrey M. Dudek, Leonardo Dueñas-Osorio, and Moshe Y. Vardi
While the Ising model is most often used to understand physical phenomena, its natural connection to combinatorial reasoning also makes it one of the best models to probe complex systems in science and engineering. We bring a computational lens to the study of Ising models, where our computer-scienc…
[Phys. Rev. E 109, 055301] Published Mon May 06, 2024
Abstract
The thermospheric column O/N2 ratio (ΣO/N2) exhibits complex spatial and temporal variations and is a key parameter in diagnosing the state of the thermosphere and ionosphere. The solar cycle, seasonal, latitudinal and longitudinal variations of ΣO/N2 have been studied in the past few decades. However, the local time variation of ΣO/N2 is rarely investigated. At solstice, the most important feature of ΣO/N2 is the well-known summer-winter difference caused by the global meridional circulation. Based on TIMED/GUVI observations from 2002 to 2022, it was found that the daytime pattern of ΣO/N2 exhibits significant hemispheric differences superimposed on the more prominent seasonal distribution. ΣO/N2 decreases soon after sunrise in the winter hemisphere, while it occurs much later in the summer hemisphere. This hemispheric difference in the local time variation of ΣO/N2 is generally reproduced by the empirical model MSIS and the physics-based model TIEGCM. And the TIEGCM simulation results suggest that it is mainly attributed to the meridional advection. In the summer hemisphere, upward winds which decrease ΣO/N2 are weak in the early morning and compete with the enhancement of ΣO/N2 caused by the meridional advection, resulting in a later turning time around 11:00 LT. In the winter hemisphere, the reduction of ΣO/N2 caused by daytime upward winds is superimposed on the reduction of ΣO/N2 induced by the meridional advection, resulting in an earlier turning time around 7:00 LT. Additionally, ΣO/N2 peaks much later in regions near the magnetic pole than those far from the magnetic pole in the summer hemisphere.
Assessing locations susceptible to shallow landslide initiation during prolonged intense rainfall in the Lares, Utuado, and Naranjito municipalities of Puerto Rico
Rex L. Baum, Dianne L. Brien, Mark E. Reid, William H. Schulz, and Matthew J. Tello
Nat. Hazards Earth Syst. Sci., 24, 1579–1605, https://doi.org/10.5194/nhess-24-1579-2024, 2024
We mapped potential for heavy rainfall to cause landslides in part of the central mountains of Puerto Rico using new tools for estimating soil depth and quasi-3D slope stability. Potential ground-failure locations correlate well with the spatial density of landslides from Hurricane Maria. The smooth boundaries of the very high and high ground-failure susceptibility zones enclose 75 % and 90 %, respectively, of observed landslides. The maps can help mitigate ground-failure hazards.
Abstract
On behalf of the journal, AGU, and the scientific community, the editors of Geophysical Research Letters would like to sincerely thank those who reviewed manuscripts for us in 2023. The hours reading and commenting on manuscripts not only improve the manuscripts, but also increase the scientific rigor of future research in the field. With the advent of AGU's data policy, many reviewers have also helped immensely to evaluate the accessibility and availability of data, and many have provided insightful comments that helped to improve the data presentation and quality. We greatly appreciate the assistance of the reviewers in advancing open science, which is a key objective of AGU's data policy. We particularly appreciate the timely reviews in light of the demands imposed by the rapid review process at Geophysical Research Letters. We received 4,512 submissions in 2023 and 5,112 reviewers contributed to their evaluation by providing 8,587 reviews in total. We deeply appreciate their contributions.
Abstract
The paper deals with the linearized Molodensky problem, when data are supposed to be square integrable on the telluroid S, proving that a solution exists, is unique and is stable in a space of harmonic functions with square integrable gradient on S. A similar theorem has already been proved by Sansò and Venuti (J Geod 82:909–916, 2008). Yet the result basically requires that S should have an inclination of less than
\(60^\circ \)
with respect to the vertical, or better to the radial direction. This constraint could result in a severe regularization for the telluroid specially in mountainous areas. The paper revises the result in an effort to improve the above estimates, essentially showing that the inclination of S could go up to
\(75^\circ \)
. At the same time, the proof is made precise mathematically and hopefully more readable in the geodetic community.
Abstract
In existing global navigation satellite system-interference reflectometry (GNSS-IR) research, only the frequency of signal-to-noise ratio (SNR) oscillations has been used to estimate sea-level height. However, the characteristic parameters of SNR oscillations are not isolated from each other, and a single feature cannot accurately and comprehensively capture the environmental changes of reflecting surface. Our simulation results show that for the nonlinear least squares (NLS), when there is a certain difference between the fitting frequency and the actual frequency of SNR oscillations, the deviation of the phase solution obtained is approximately linear with the frequency difference. Consequently, a linear phase correction GNSS-IR sea-level estimation method is constructed in this study. This method integrates the Lomb–Scargle periodogram (LSP) and NLS to process SNR oscillations, using the phase obtained from NLS to correct the retrieval error of LSP. Through processing SNR data from four sites for nearly half a year, we verified the stability of the relationship between phase and frequency-based retrieval error at different sites in continuous monitoring, and established the relationship model between the two. Then, utilizing the relationship model acquired at different sites, we estimated the sea-level variations for the next 6 months at each site through joint frequency and phase versus reflector height relationships. Experimental results show that the phases acquired from NLS can effectively correct the retrieval error of LSP. Compared with the traditional method using only frequency, the root mean square error and mean absolute error of the retrieval results obtained from the linear phase correction GNSS-IR sea-level estimation method based on LSP-NLS are both reduced by about 60%. This multi-feature fusion technique introduces a new perspective and technical approach for GNSS-IR sea-level estimations.
Magmas, especially mafic ones, usually intrude into the upper crust as dikes. The intruded dike is often arrested before reaching the surface to make an eruption. Many geophysical observations, including geode...
Nature Geoscience, Published online: 06 May 2024; doi:10.1038/s41561-024-01431-3
Maintenance of estuarine tidal flats requires a minimum turbidity level that increases with tidal range, according to a global analysis of tidal-flat changes from satellite imagery.
Nature Geoscience, Published online: 06 May 2024; doi:10.1038/s41561-024-01444-y
Hydrothermal flow pathways and extent of alteration within serpentinized peridotite in Mid-Atlantic Ridge oceanic core complexes are modulated by mafic intrusions, according to full waveform inversion of seismic data and local earthquake tomography.
Abstract
Mesoscale convective systems (MCSs) are crucial components of the hydrological cycle and often produce flash floods. Given their impact, it is important to understand how they will change under a warming climate. This study uses a satellite- and radar-based MCS tracking algorithm on convection-permitting climate model simulations and examines changes in MCS properties and precipitation structures between historical and future simulations. An underestimation in MCS total precipitation is evident in historical simulation compared to observations, due to model's depiction of MCS precipitation area and summertime occurrence frequency. Under pseudo-global warming, increases in MCS frequency and total warm season precipitation are observed, most notably in the southern U.S. The precipitation intensity and precipitating area generated by future MCSs also rises and results in an increase in precipitation volume. MCS precipitation structures are further classified into convective core and stratiform regions to understand how change in these structures contributes to future rainfall changes. In a warmer climate, the stratiform region demonstrates minimal change in size, but increases in mean precipitation rate and mean maximum precipitation rate by 15% and 29% are noted, respectively. A more robust future response is observed in the convective core region, with its size, mean precipitation rate and mean maximum precipitation rate increasing significantly by 24%, 37% and 42%, respectively. Finally, by examining the environmental properties of MCS initial condition, future intensification of convective rain may be attributed to a combined effect of substantial increases in atmospheric instability and moisture availability.
Abstract
Observations of wind distribution in the eye of tropical cyclones (TCs) are still limited. In this study, a method to derive atmospheric motion vectors (AMVs) for TCs is developed, where selection from multiple local rotation speeds is made by considering continuity among neighboring grid points. The method is applied to 2.5-min interval image sequences of three TCs, Lan (2017), Haishen (2020), and Nanmadol (2022), observed by the Himawari-8 satellite. The results are compared with AMVs derived from research-based 30-s Himawari-8 special observations conducted for Haishen and Nanmadol, as well as with in-situ dropsonde observations conducted for Lan and Nanmadol. In these storms, the AMVs obtained from the 2.5-min interval images in the eye are found to be in good agreement with the dropsonde observations. Examinations of AMVs in the eye reveal transient azimuthal wavenumber-1 features in all three TCs. These features are consistent with algebraically growing wavenumber-1 disturbances, which transport angular momentum inward and accelerate the eye rotation. In the case of Lan, the angular velocity in the eye increased by approximately 1.5 times within 1 hr. This short-term increase is further examined. Visualization of low-level vorticity in the eye and angular momentum budget analysis suggest that angular momentum transport associated with mesovortices played an important role in the increase of tangential wind and the homogenization of angular velocity in the eye of Lan.
Abstract
A better understanding of vertical distributions of aerosol and cloud droplet number concentrations is important for the study of aerosol-cloud interaction which is one of the key uncertainties in climate change projection. In this study, we compared the aerosol mass and number concentrations simulated by a size-resolved advanced particle microphysics (APM) package coupled with a global 3-D chemical transport model (GEOS-Chem) with the NASA’s Atmospheric Tomography Mission (ATom) measurements at the Pacific Ocean and the Atlantic Ocean during ATom-1 and ATom-2 campaign periods. Generally, the model captured the spatial pattern and seasonal variation of aircraft observed aerosol mass and number concentrations. The model simulated cloud droplet number concentrations (CDNC) were compared with CloudSat retrievals whose orbits were nearby ATom's flight tracks on the same days. Correlation coefficients of simulated and retrieved CDNC at ATom-1 Pacific Ocean, ATom-1 Atlantic Ocean, ATom-2 Pacific Ocean, and ATom-2 Atlantic Ocean are 0.83, 0.97, 0.87, and 0.73, respectively. Both satellite retrievals and model simulations indicated that the averaged values of CDNC at the Pacific Ocean and the Atlantic Ocean during ATom-1 and ATom-2 periods decreased with altitudes. The ratio of CDNC in the lower troposphere (1,000–800 hPa) to those in the middle troposphere (600–400 hPa) was 1.9 (1.6–2.3) based on CloudSat retrievals and 2.2 (1.2–3.0) based on the model simulations. Model analysis indicated that secondary particles dominate CDNC in the atmosphere and primary organic aerosols have important contributions to CDNC, especially at the Atlantic Ocean during ATom-1.
