Feed aggregator

Taylor Swift fans literally made the earth move as the US singer-songwriter began her UK tour, the British Geological Survey said on Thursday, with seismic activity recorded six kilometers (nearly four miles) away.

2021 Alaska Earthquake: entropy approach to its precursors and aftershock regimes
Eugenio E. Vogel, Denisse Pastén, Gonzalo Saravia, Michel Aguilera, and Antonio Posadas
Nat. Hazards Earth Syst. Sci. Discuss., https//doi.org/10.5194/nhess-2024-106,2024
Preprint under review for NHESS (discussion: open, 0 comments)
For the first time, an entropy analysis has been performed in Alaska, a seismic-rich region located in a subduction zone that shows non-trivial behavior: the subduction arc changes seismic activity from the eastern zone to the western zone, showing a decrease in this activity along subduction. This study shows how an entropy approach can help understand seismicity in subduction zones.

Scale size estimation and flow pattern recognition around a magnetosheath jet
Adrian Pöppelwerth, Georg Glebe, Johannes Z. D. Mieth, Florian Koller, Tomas Karlsson, Zoltán Vörös, and Ferdinand Plaschke
Ann. Geophys., 42, 271–284, https://doi.org/10.5194/angeo-42-271-2024, 2024
In the magnetosheath, a near-Earth region of space, we observe increases in plasma velocity and density, so-called jets. As they propagate towards Earth, jets interact with the ambient plasma. We study this interaction with three spacecraft simultaneously to infer their sizes. While previous studies have investigated their size almost exclusively statistically, we demonstrate a new method of determining the sizes of individual jets.

Author(s): Jiajun Li, Hanchen Xue, Zhaohua Wang, Xianzhi Wang, Jiawen Li, Yingfeng Li, Guodong Zhao, and Zhiyi Wei

Here a mechanism for self-compression of laser pulses is presented, based on period density-modulated plasma. In this setup, two pump beams intersect at a small angle within the plasma. This interaction is facilitated by the ponderomotive ion mechanism, which causes a modulation in the density of pl…

[Phys. Rev. E 109, 065208] Published Thu Jun 13, 2024

When Hurricane Sally slammed coastal Florida in 2020, US pilot Dean Legidakes was aboard a scientific aircraft flying directly into the storm's core.

Abstract

There are many uncertainties in future climate, including how the Earth may react to different types of radiative forcing, such as CO2, aerosols, and even geoengineered changes in the amount of sunlight absorbed by Earth's surface. Here, we analyze model simulations where the climate system is subjected to an abrupt change of the solar constant by ±4%, and where the atmospheric CO2 concentration is abruptly changed to quadruple and half its preindustrial value. Using these experiments, we examine how clouds respond to changes in solar forcing, compared to CO2, and feedback on global surface temperature. The total cloud response can be decomposed into those responses driven by changes in global surface temperature, called the temperature mediated cloud feedbacks, and responses driven directly by the forcing that are independent of the global surface temperature. In this paper, we study the temperature mediated cloud changes to answer two primary questions: (a) How do temperature mediated cloud feedbacks differ in response to abrupt changes in CO2 and solar forcing? And (b) Are there symmetrical (equal and opposite) temperature mediated cloud feedbacks during global warming and global cooling? We find that temperature mediated cloud feedbacks are similar in response to increasing solar and increasing CO2 forcing, and we provide a short review of recent literature regarding the physical mechanisms responsible for these feedbacks. We also find that cloud responses to warming and cooling are not symmetric, due largely to non-linearity introduced by phase changes in mid-to-high latitude low clouds and sea ice loss/formation.

Science, Volume 384, Issue 6701, June 2024.

Abstract

The divergence method, a lightweight approach for estimating emission fluxes from satellite images, rests on a few implicit assumptions. This paper explicitly outlines these assumptions by deriving the method from first principles. The assumptions are: the enhanced mass flux is dominated by advection, normal fluxes vanish at the top and bottom of the atmosphere, steady-state conditions apply, sources are multiplications of temporal and spatial functions, sinks are described as first-order reactions, and effective wind fields are concentration-weighted wind fields. No such assumptions have to be made for the background field. A “topography correction term” does not follow from the theory, but is rather shown to be a practical correction for topography-dependent effective wind speed errors. The cross-sectional flux method follows naturally from the derived theory, and the methods are compared. Effects of discrete pixels and finite-difference operations are explored, leading to recommendations, primarily the recommendation to integrate over small regions only to minimize the influence of noise. Numerical examples featuring Gaussian plumes and COSMO-GHG simulated plumes are provided. The Gaussian plume example suggests that the divergence method might underestimate emissions when assuming only advection in the presence of cross-wind diffusion. Conversely, the cross-sectional flux method remains unaffected, provided fluxes are integrated across the entire plume. The COSMO-GHG example reveals frequent violations of the steady-state assumption, although the assumption remains valid proximal to the source (<20 km in this example). It is the hope that this paper provides a solid theoretical foundation for the divergence and cross-sectional flux methods.

Science, Volume 385, Issue 6706, Page 318-321, July 2024.

Science, Volume 385, Issue 6705, Page 188-194, July 2024.

Science, Volume 384, Issue 6703, Page 1460-1467, June 2024.

Science, Volume 384, Issue 6703, Page 1453-1460, June 2024.

Science, Volume 384, Issue 6701, Page 1180-1180, June 2024.

Science, Volume 384, Issue 6701, Page 1181-1181, June 2024.

Science, Volume 384, Issue 6701, Page 1227-1235, June 2024.

Science, Volume 384, Issue 6701, Page 1235-1240, June 2024.

Science, Volume 384, Issue 6701, Page 1196-1202, June 2024.

Science, Volume 384, Issue 6701, Page 1203-1212, June 2024.

Science, Volume 384, Issue 6701, Page 1259-1265, June 2024.

Science, Volume 384, Issue 6701, Page 1241-1247, June 2024.