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May 2024 was the warmest May on the books, marking a full year of record-high monthly temperatures, NASA scientists found. Average global temperatures for the past 12 months hit record highs for each respective month—an unprecedented streak—according to scientists from NASA's Goddard Institute for Space Studies (GISS) in New York.

When old satellites fall into Earth's atmosphere and burn up, they leave behind tiny particles of aluminum oxide, which eat away at Earth's protective ozone layer. A new study finds that these oxides have increased 8-fold between 2016 and 2022 and will continue to accumulate as the number of low-Earth-orbit satellites skyrockets.

Abstract

The radius of maximum wind (RMW) defines the location of the maximum winds in a tropical cyclone and is critical to understanding intensity change as well as hazard impacts. A comparison between the Hurricane Analysis and Forecast System (HAFS) models and two statistical models based off the National Hurricane Center official forecast is conducted relative to a new baseline climatology to better understand whether models have skill in forecasting the RMW of North Atlantic tropical cyclones. On average, the HAFS models are less skillful than the climatology and persistence baseline and two statistically derived RMW estimates. The performance of the HAFS models is dependent on intensity with better skill for stronger tropical cyclones compared to weaker tropical cyclones. To further improve guidance of tropical cyclone hazards, more work needs to be done to improve forecasts of tropical cyclone structure.

Deposits of deep-pink sand washing up on South Australian shores shed new light on when the Australian tectonic plate began to subduct beneath the Pacific plate, as well as the presence of previously unknown ancient Antarctic mountains.

Development and evaluation of the interactive Model for Air Pollution and Land Ecosystems (iMAPLE) version 1.0
Xu Yue, Hao Zhou, Chenguang Tian, Yimian Ma, Yihan Hu, Cheng Gong, Hui Zheng, and Hong Liao
Geosci. Model Dev., 17, 4621–4642, https://doi.org/10.5194/gmd-17-4621-2024, 2024
We develop the interactive Model for Air Pollution and Land Ecosystems (iMAPLE). The model considers the full coupling between carbon and water cycles, dynamic fire emissions, wetland methane emissions, biogenic volatile organic compound emissions, and trait-based ozone vegetation damage. Evaluations show that iMAPLE is a useful tool for the study of the interactions among climate, chemistry, and ecosystems.

StraitFlux – precise computations of water strait fluxes on various modeling grids
Susanna Winkelbauer, Michael Mayer, and Leopold Haimberger
Geosci. Model Dev., 17, 4603–4620, https://doi.org/10.5194/gmd-17-4603-2024, 2024
Oceanic transports shape the global climate, but the evaluation and validation of this key quantity based on reanalysis and model data are complicated by the distortion of the used modelling grids and the large number of different grid types. We present two new methods that allow the calculation of oceanic fluxes of volume, heat, salinity, and ice through almost arbitrary sections for various models and reanalyses that are independent of the used modelling grids.

Abstract

In the Arctic and subarctic oceans, the relatively low supply of silicon (compared to other nutrients) can make it limiting for the growth of diatoms, a fundamental building block of the oceanic food web. Glaciers release large quantities of dissolved silicon and dissolvable solid amorphous silica phases into high-latitude estuaries (fjords), but the role of these glacially-derived silica phases in sustaining diatom growth in the coastal and open-water sectors remains unknown. Here we show how stable and radiogenic silicon isotopes can be used together to address this question, using southwest Greenland as a case study. This study finds enhanced levels of detrital (i.e., mineral) amorphous silica, likely glacially-sourced, sustaining a large portion of diatom growth observed off the coast, revealing how the phytoplankton community can function during high-meltwater periods.

Abstract

The ocean's organic carbon export is a key control on atmospheric pCO2 and stimulating this export could potentially mitigate climate change. We use a data-constrained model to calculate the sensitivity of atmospheric pCO2 to local changes in export using an adjoint approach. A perpetual enhancement of the biological pump's export by 0.1 PgC/yr could achieve a roughly 1% reduction in pCO2 at average sensitivity. The sensitivity varies roughly 5-fold across different ocean regions and is proportional to the difference between the mean sequestration time τ seq of regenerated carbon and the response time τ pre of performed carbon, which is the reduction in the preformed carbon inventory per unit increase in local export production. Air-sea CO2 disequilibrium modulates the geographic pattern of τ pre, causing particularly high sensitivities (2–3 times the global mean) in the Antarctic Divergence region of the Southern Ocean.

A class of Iowa State University storm chasers abandoned a remote ridge near Carbon, Iowa, and started driving south to get out of the way of an approaching tornado.

About 2.5 billion years ago, free oxygen, or O2, first started to accumulate to meaningful levels in Earth's atmosphere, setting the stage for the rise of complex life on our evolving planet.

Abstract

The Cross-track Infrared Sounder (CrIS) observations (O) contributed greatly to numerical weather prediction. Further contribution depends on the success of all-sky data assimilation, which requires a method to produce realistic cloud/rain band structures from background fields (i.e., 6-hr forecasts), and to remove large biases of all-sky simulation of brightness temperature (TB) in the presence of clouds. In this study, CrIS all-sky simulations of brightness temperatures at an arbitrarily selected window channel within Typhoon Hinnamnor (2022) are investigated. The 3-km Weather Research and Forecasting model with three microphysics schemes were used to produce 6-hr background forecasts (B). The O − B statistic deviate greatly from Gaussian distribution with large biases in either water clouds, or thin ice clouds, or thick ice clouds within Typhoon Hinnamnor. By developing a linear regression function of three all-sky simulations of TB from 6-hr forecasts with three microphysics schemes, the O − B statistics approximate a Gaussian normal distribution in water clouds, thin ice clouds and thick ice clouds. Taking the regression function that is established by a training data set to combine 6-hr background forecasts at later times, the cloud/rain band structures compared much more favorably with CrIS observations than those from an individual microphysic. Furthermore, the regression coefficients derived from Typhoon Hinnamnor (2022) also work for Typhoon Khanun (2023). The work aims to quantify and remove biases in background fields of TB and generating realistic typhoon cloud/rain band structures in background fields will allow a better description of center position, intensity and size to improve typhoon forecasts.

A key to improving climate prediction is to improve understanding of the impact of aerosol on clouds, commonly known as the aerosol-cloud-interaction, according to a new study led by Earth System Science Interdisciplinary Center (ESSIC) researchers published in Science Advances.

Abstract

The stepwise development of positive lightning leaders is still not well understood. A recent laboratory study indicated, at high absolute humidity, positive leaders can do steps due to the merging of a separate luminous structure and the primary leader channel, similar to the steps of negative leaders. The humidity may play a key role in the formation of positive leader steps, however, the humidity effect on the positive leader steps has never been explored. In this paper, we examine numerous positive long spark discharges at different humidity levels with the synchronized discharge current and high-speed camera frames recording the evolution of leader channel. The positive leader propagation manners at different humidity levels are compared both morphologically and electrically. The effect of humidity on steps is further analyzed statistically. We found that the positive leader steps characterized by steep-rise current pulse and abrupt channel elongation, which may be led by separate luminous structures, only appear under the condition that high absolute humidity is above a certain threshold. As the ambient humidity increases, these positive leader steps occur more frequently.

Abstract

The long-term trends and seasonality of many tropospheric pollutants are not well characterized in the high Arctic due to a dearth of trace-gas measurements in this remote region. In this study, the inter- and intra-annual variabilities of carbon monoxide (CO), acetylene (C2H2), ethane (C2H6), methanol (CH3OH), formaldehyde (H2CO), formic acid (HCOOH), and peroxyacetyl nitrate (PAN) in the high Arctic region were derived from the total column time-series of ground-based Fourier transform infrared (FTIR) measurements at Eureka, Nunavut (80.05°N, 86.42°W, 2006–2020) and Thule, Greenland (76.53°N, 68.74°W, 1999–2022). Consistent seasonal cycles were observed in the FTIR measurements at both sites for all species. Negative trends were observed for CO, C2H2, and CH3OH at both sites, and for HCOOH at Eureka. Positive trends were detected for C2H6 and H2CO at both sites, and for PAN at Eureka. Additionally, a 19-year simulation was performed using the novel GEOS-Chem High Performance model v14.1.1 for the period of 2003–2021. The model was able to reproduce the observed seasonality of all gases, but all species showed negative biases relative to observations, and CH3OH was found to have a particularly large bias of approximately −70% relative to the FTIR measurements. The GEOS-Chem modeled trends broadly agreed with observations for all species except C2H6, H2CO, and PAN, which were found to have opposite trends in the model. For some species, the measurement-model differences are suspected to be the result of errors or underestimations in the emissions inventories used in the simulation.

Abstract

Current models estimate global aviation contributes approximately 5% to the total anthropogenic climate forcing, with aerosol-cloud interactions having the greatest effect. However, radiative forcing estimates from aviation aerosol-cloud interactions remain undetermined. There is an expected significant increase in aircraft emissions with aviation demand expected to rise by over 4% per year. Soot may play an important role in the ice nucleation of aircraft-induced cirrus formation due to a high emission rate, but the ice nucleating properties are poorly constrained. Understanding the microphysical processes leading to atmospheric ice crystal formation is crucial for the reliable parameterization of aerosol-cloud interactions in climate models due to their impact on precipitation and cloud radiative properties. Ice nucleation of aircraft-emitted soot is potentially affected by particle morphology with condensation of supercooled water occurring in pores followed by ice nucleation. However, soot has heterogeneous properties and undergoes atmospheric aging and oxidation that could change surface properties and contribute to complex ice nucleation processes. This review synthesizes current knowledge of ice nucleation catalyzed by aviation in the cirrus regime and its effects on global radiative forcing. Further research is required to determine the ice nucleation and microphysical processes of cirrus cloud formation from aviation emissions in both controlled laboratory and field investigations to inform models for more accurate climate predictions and to provide efficient mitigation strategies.

Abstract

The thermospheric density and its variations are crucial to aerospace activities as well as space weather research and operation. However, due to the difficulties in observing the thermosphere, there has been a lack of effective descriptions for the general characteristics of thermospheric density. In this paper, the Two-Line-Element data sets (TLEs) from multi-target low Earth orbit satellites are used to derive a proxy of the daily average atmospheric density in the thermospheric shell located in the vicinity of LEOs' orbital altitude. It captures the overall characteristics of the thermosphere and exhibits good correlations (∼0.9) with modeled and observed thermospheric density. By applying the spectral whitening method to this proxy, a new index JsT ${J}_{s}^{T}$ is derived to describe non-periodic perturbation of the density where the specific satellite passed by. The fact that the JsT ${J}_{s}^{T}$ obtained from different satellites within the same thermospheric shell presents significant consistency to each other means that the new index is a good indicator for the overall feature of the variations of thermospheric density, and it is possible to define a unified regional index JrT ${J}_{r}^{T}$ to describe density disturbances for the thermospheric shell where these satellites fly through. Moreover, the JrT ${J}_{r}^{T}$ at different altitudes also present good consistency suggesting the possibility of defining a global index JpT ${J}_{p}^{T}$, capable of describing the density variation of the entire thermosphere.

Global warming is an omnipresent issue, with widespread initiatives to draw down emissions and mitigate against the International Panel on Climate Change's worse-case scenario predictions of 3.2°C of warming by 2100 (relative to pre-Industrial levels). Current measurements stand at 1.1°C of warming across Earth, but polar regions are experiencing enhanced surface warming compared to the rest of the planet.

Abstract

Davemaoite, that is, CaSiO3 perovskite (CaPv), is the third most abundant phase in the lower mantle and exhibits a tetragonal-cubic phase transition at high pressures and temperatures. The phase boundary in CaPv has recently been proposed to be close to the cold slab adiabat and cause mid-mantle seismic wave speed anomalies (Thomson et al., 2019, https://doi.org/10.1038/s41586-019-1483-x). This study utilized accurate deep-learning-based simulations and thermodynamic integration techniques to compute free energies at temperatures ranging from 300 to 3,000 K and pressures up to 130 GPa. Our results indicate that CaPv exhibits a single cubic phase throughout lower-mantle conditions. This suggests that the phase diagram proposed by Thomson et al. requires revision, and mid-mantle seismic anomalies are likely attributable to other mechanisms.

A systemic and comprehensive assessment of coastal hazard changes: method and application to France and its overseas territories
Marc Igigabel, Marissa Yates, Michalis Vousdoukas, and Youssef Diab
Nat. Hazards Earth Syst. Sci., 24, 1951–1974, https://doi.org/10.5194/nhess-24-1951-2024, 2024
Changes in sea levels alone do not determine the evolution of coastal hazards. Coastal hazard changes should be assessed using additional factors describing geomorphological configurations, metocean event types (storms, cyclones, long swells, and tsunamis), and the marine environment (e.g., coral reef state and sea ice extent). The assessment completed here, at regional scale including the coasts of mainland and overseas France, highlights significant differences in hazard changes.

Conversion relationships between Modified Mercalli Intensity and Peak Ground Acceleration for historical shallow crustal earthquakes in Mexico
Quetzalcoatl Rodríguez-Pérez and F. Ramón Zúñiga
Nat. Hazards Earth Syst. Sci. Discuss., https//doi.org/10.5194/nhess-2024-92,2024
Preprint under review for NHESS (discussion: open, 1 comment)
Seismic intensity reflects earthquake damage, although this parameter is often subjective. On the other hand, peak acceleration values are a direct measure of earthquake effects. Seismic intensity was used to describe historical earthquakes, and its use is rare today. For this reason, it is important to have a relationship between these parameters of strong movements in order to predict the acceleration of historical earthquakes.