Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title><jats:p>Shocklets and short large‐amplitude magnetic structures (SLAMS) are steepened magnetic fluctuations commonly found in Earth's upstream foreshock. Here we present <jats:italic>Venus Express</jats:italic> observations from the 26th of February 2009 establishing their existence in the steady‐state foreshock of Venus, building on a past study which found SLAMS during a substantial disturbance of the induced magnetosphere. The Venusian structures were comparable to those reported near Earth. The 2 Shocklets had magnetic compression ratios of 1.23 and 1.34 with linear polarization in the spacecraft frame. The 3 SLAMS had ratios between 3.22 and 4.03, two of which with elliptical polarization in the spacecraft frame. Statistical analysis suggests SLAMS coincide with unusually high solar wind Alfvén mach‐number at Venus (12.5, this event). Thus, while we establish Shocklets and SLAMS can form in the stable Venusian foreshock, they may be rarer than at Earth. We estimate a lower limit of their occurrence rate of ≳14%.</jats:p>

<jats:title>Abstract</jats:title><jats:p>Water vapor's contribution to Earth's radiative forcing is most sensitive to changes in its lower stratosphere concentration. One recognized pathway for rapid increases in stratospheric water vapor is tropopause‐overshooting convection. Since this pathway has been rarely sampled, the NASA Dynamics and Chemistry of the Summer Stratosphere (DCOTSS) field project focused on obtaining in situ observations of stratospheric air recently affected by convection over the United States. This study reports on the extreme altitudes to which convective hydration was observed. The data show that the overworld stratosphere is routinely hydrated by convection and that past documented records of stratospheric heights of convective hydration were exceeded during several DCOTSS flights. The most extreme event sampled is highlighted, for which stratospheric water vapor was increased by up to 26% at an altitude of 19.25 km, a potential temperature of 463 K, and an ozone mixing ratio &gt;1500 ppbv.</jats:p>

<jats:title>Abstract</jats:title><jats:p>The Southern Hemispheric storm tracks exhibit a robust intraseasonal periodicity of 20–30 days as the leading mode of zonal‐mean eddy kinetic energy. To what extent this hemispheric‐scale mode of variability translates to smaller scales remains debated. This work studies the regional features of Southern Hemisphere storm tracks through a filtered variance analysis of local finite‐amplitude wave activity. While the synoptic variance is zonally elongated over the storm track, we find a strong enhancement of intraseasonal variability within the South Pacific. With a minimum strength of the storm track, this region is marked with 20–30 day periodic behavior of local wave activity and precipitation and is driven by enhanced variability of low‐level eddy heat flux on the same timescale. The local nature of 20–30 day periodicity offers a potential source of subseasonal to seasonal predictability for weather analysts and forecasters.</jats:p>

<jats:title>Abstract</jats:title><jats:p>On 15 January 2022, the Hunga Tonga‐Hunga Ha'apai (HT) eruption injected SO<jats:sub>2</jats:sub> and water into the middle stratosphere. The SO<jats:sub>2</jats:sub> is rapidly converted to sulfate aerosols. The aerosol and water vapor anomalies have persisted in the Southern Hemisphere throughout 2022. The water vapor anomaly increases the net downward IR radiative flux whereas the aerosol layer reduces the direct solar forcing. The direct solar flux reduction is larger than the increased IR flux. Thus, the net tropospheric forcing will be negative. The changes in radiative forcing peak in July and August and diminish thereafter. Scaling to the observed cooling after the 1991 Pinatubo eruption, HT would cool the 2022 Southern Hemisphere's average surface temperatures by less than 0.037°C.</jats:p>

<jats:title>Abstract</jats:title><jats:p>Submarine landslides shape continental margins, transfer massive amounts of sediment downslope, and can generate deadly and destructive tsunamis. Submarine landslides are common globally, yet constraining hazard potential of future events is limited by a short historical record and a wide range of possible slide dynamics. We test a novel approach to investigate slide dynamics using properties of the deformation zone induced by a large submarine landslide along the Cascadia margin, offshore Oregon. We use a simple model of a line load on a poroelastic half space to show the deformation zone size required rapid transport and deceleration. We argue that the slide moved at high speeds, aided by low dynamic frictional resistance, suggesting this event could have generated a tsunami. This method is applicable where slide‐induced impact zones are observed.</jats:p>

<jats:title>Abstract</jats:title><jats:p>The Gulf Stream is a vital limb of the North Atlantic circulation that influences regional climate, sea level, and hurricane activity. Given the Gulf Stream's relevance to weather and climate, many studies have attempted to estimate trends in its volumetric transport from various data sets, but results have been inconclusive, and no consensus has emerged whether it is weakening with climate change. Here we use Bayesian analysis to jointly assimilate multiple observational data sets from the Florida Straits to quantify uncertainty and change in Gulf Stream volume transport since 1982. We find with virtual certainty (probability <jats:italic>P</jats:italic> &gt; 99%) that Gulf Stream volume transport through the Florida Straits declined by 1.2 ± 1.0 Sv in the past 40 years (95% credible interval). This significant trend has emerged from the data set only over the past ten years, the first unequivocal evidence for a recent multidecadal decline in this climate‐relevant component of ocean circulation.</jats:p>

<jats:title>Abstract</jats:title><jats:p>Impacts of small‐scale surface irregularities, or surface roughness, of atmospheric ice crystals on lidar backscattering properties are quantified. Geometric ice crystal models with various degrees of surface roughness and state‐of‐the‐science light‐scattering computational capabilities are utilized to simulate the single‐scattering properties across the entire practical size parameter range. The simulated bulk lidar and depolarization ratios of polydisperse ice crystals at wavelength 532 nm are strongly sensitive to the degree of surface roughness. Comparisons of these quantities between the theoretical simulations and counterparts inferred from spaceborne lidar observations for cold cirrus clouds suggest a typical surface‐roughness‐degree range of 0.03–0.15 in the cases of compact hexagonal ice crystals, which is most consistent with direct measurements of scanning electron microscopic images. To properly interpret lidar backscattering observations of ice clouds, it is necessary to account for the degree of surface roughness in light‐scattering computations involving ice crystals.</jats:p>

<jats:title>Abstract</jats:title><jats:p>In the absence of consistent meteorological data on Mars, the morphology of dunes can be employed to study its atmosphere. Specifically, barchan dunes, which form under approximately unimodal winds, are reliable proxies for the dominant wind directions. Here, we characterize near‐surface winds on Mars from the morphology of &gt;700,000 barchans mapped globally on the planet by a convolutional neural network. Barchan migration is predominantly aligned with known southern‐summer atmospheric circulation patterns—northerly at mid‐latitudes and cyclonic near the north pole—with the addition of an anti‐cyclonic north‐polar component that likely originates from winds emerging from the ice cap. Locally, migration directions deviate from regional trends in areas with high topographic roughness. Notably, obstacles &lt;100 km such as impact craters are efficient at deflecting surface winds. Our database, which provides insights into planetary‐scale aeolian processes on modern‐day Mars, can be used to constrain global circulation models to assist with predictions for future missions.</jats:p>

<jats:title>Abstract</jats:title><jats:p>Schmidt, Jones, and Kennedy’s (SJK) (2023, <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://doi.org/10.1029/2022GL102530">https://doi.org/10.1029/2022GL102530</jats:ext-link>) critique of Scafetta (2022, <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://doi.org/10.1029/2022GL097716">https://doi.org/10.1029/2022GL097716</jats:ext-link>) is flawed. Their assessment of the error of the ERA‐T2m 2011–2021 mean (≈0.10°C) is 5–10 times overestimated and contradicts published literature. SJK confused natural variability with random noise and mistook the error of the mean of a temperature chronology for the stochastic error of the regression parameter <jats:italic>M</jats:italic> of a nonphysical isothermal climate model (<jats:italic>T</jats:italic>(<jats:italic>t</jats:italic>) = <jats:italic>M</jats:italic>). SJK's allegations regarding the internal variability of the models, the role of the global climate model ensemble members, and other issues were partially addressed in Scafetta (2022, <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://doi.org/10.1029/2022GL097716">https://doi.org/10.1029/2022GL097716</jats:ext-link>) and, later, more extensively in Scafetta (2023a, <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://doi.org/10.1007/s00382-022-06493-w">https://doi.org/10.1007/s00382-022-06493-w</jats:ext-link>) where Scafetta's (2022, <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://doi.org/10.1029/2022GL097716">https://doi.org/10.1029/2022GL097716</jats:ext-link>) conclusions were confirmed.</jats:p>

<jats:title>Abstract</jats:title><jats:p>Hydrogen (H<jats:sub>2</jats:sub>) is the most abundant constituent in giant planets, but its thermal conductivity <jats:italic>Λ</jats:italic> under extreme pressure‐temperature (<jats:italic>P‐T</jats:italic>) conditions remains largely unknown. Here we report the <jats:italic>Λ</jats:italic> of H<jats:sub>2</jats:sub> from ambient to 60.2 GPa at 300 K and from 300 to 773 K at 2.1 GPa. At 300 K, the <jats:italic>Λ</jats:italic> of liquid H<jats:sub>2</jats:sub> fluctuates at ∼0.7–1.1 W m<jats:sup>−1</jats:sup> K<jats:sup>−1</jats:sup>. Upon crystallization to H<jats:sub>2</jats:sub>‐I phase, the <jats:italic>Λ</jats:italic> jumps to 5.5 W m<jats:sup>−1</jats:sup> K<jats:sup>−1</jats:sup> at 7.2 GPa, and monotonically increases with pressure to ∼27 W m<jats:sup>−1</jats:sup> K<jats:sup>−1</jats:sup> at 60.2 GPa. Upon heating, the <jats:italic>Λ</jats:italic> of liquid H<jats:sub>2</jats:sub> at 2.1 GPa scales with <jats:italic>T</jats:italic><jats:sup>0.68</jats:sup>. Moreover, the density (ρ)‐dependent compressional sound velocity (<jats:italic>V</jats:italic><jats:sub>p</jats:sub>) of liquid and solid H<jats:sub>2</jats:sub> derived from Brillouin frequency data both follow the Birch's law. Besides the novel insights into the physics of thermal transport in H<jats:sub>2</jats:sub> under extreme conditions, our results significantly advance the modeling of <jats:italic>Λ</jats:italic>‐<jats:italic>V</jats:italic><jats:sub>p</jats:sub>‐ρ relationship in a planet with H<jats:sub>2</jats:sub>.</jats:p>