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The January 2022 eruption of the Hunga Tonga-Hunga Ha'apai (HTHH) volcano discharged 2,900 teragrams of ejecta, most of which was deposited in the South Pacific Ocean. Here we investigate its impact on the biogeochemistry of the South Pacific Gyre (SPG) using samples collected during the GEOTRACES cruise GP21 in February-April 2022. Surface water neodymium isotopes and rare earth element compositions showed a marked volcanic impact in the western SPG, potentially extending to the eastern region. Increasing trace metal concentrations in surface waters and chlorophyll-a inventories in euphotic layers between the eastern and western SPG further suggest that the volcanic eruption supplied (micro)nutrients potentially stimulating a biological response. We estimate that the HTHH eruption released up to 0.16 kt of neodymium and 32 kt of iron into the SPG, which is comparable to the annual global dust-borne Nd flux and the annual dust-borne Fe flux to the entire SPG, respectively. Surface water neodymium isotopes and rare earth element compositions reveal a marked impact from the January 2022 Hunga Tonga-Hunga Ha'apai eruption in the western South Pacific, with released trace metals potentially stimulating biological responses. [ABSTRACT FROM AUTHOR]

Long-term ground-based lidar observations are important in estimating the contribution of different sources (mostly volcanic eruptions and wildfires) to aerosol loading of the atmosphere and in developing and improving various climate models. In this paper, we carefully analyse aerosol scattering ratio profiles and aerosol layers, observed with 532-nm lidar measurements at the Siberian Lidar Station in Tomsk (56.48°N, 85.05°E) over the period 2018–2022, and identify the layers' potential sources. To compare aerosol loading over Tomsk for the last five years (2018–2022) with that for previous years, we also present and discuss time series of integrated aerosol backscatter coefficient (IABC) for three altitude ranges. The first range (15–30 km) reveals the pure stratospheric aerosol loading provided by volcanic eruptions, the second range (11–15 km) is responsible mainly for aftereffects of wildfire smoke plumes, and the third one (11–30 km) demonstrates aerosol contribution from both sources. In particular, we found for the period 2001–2022 that the annual average IABC reached its maximal values of 2.91 × 10−4 sr−1 (15–30 km) and 8.21 × 10−4 sr−1 (11–30 km) in 2022 due to the Hunga Tonga-Hunga Ha'apai volcanic eruption. The period 2020–2022 exhibited a significant increase in the relative aerosol content at altitudes of 11–15 km in the total aerosol loading at 11–30 km over Tomsk from 54.4% in 2020 to 64.8% in 2022, which indicates a shift of the main part of aerosol loading to altitudes of 11–15 km due to the increased wildfire activity in North America and north-eastern Asia. The Arctic polar vortex is also revealed to distort the real aerosol vertical distribution over Tomsk by replacing it with the aerosol distribution inside the vortex on measurement days when the vortex is over the lidar site. [ABSTRACT FROM AUTHOR]

The article "Ionosphere Monitoring with Remote Sensing Vol II." provides an overview of the importance of studying the Earth's ionosphere and its influence on space weather. It discusses the use of remote sensing and in situ instruments to investigate ionospheric features and anomalies. The article presents original research papers that contribute to the understanding of the ionosphere and its relevance for signal transmission and space weather studies. It also explores the use of artificial intelligence technology in ionospheric prediction models and the study of ionospheric anomalies associated with natural phenomena. The research findings highlight the complex nature of the ionosphere and its impact on communication and navigation systems. [Extracted from the article]

On 15 January 2022, a massive underwater volcano erupted in the Tonga region, releasing a significant amount of volcanic ash and gases into the atmosphere. The United States Geological Survey (USGS) estimated the seismic source to have a surface wave magnitude (Ms) of 5.8. This eruption was observed from space, and the resulting atmospheric shockwave swept across the Pacific Ocean. Reports from various locations worldwide indicated rapid fluctuations in air pressure following this event. Taiwan, situated in the western Pacific, approximately 8,500 km from the eruption source, observed significant changes. During this volcanic eruption, both rapid air pressure changes and several significant changes in the Earth's physical parameters were observed in Taiwan. The Tonga eruption is a unique event, and comprehensive observations provide an opportunity to explore and explain the mechanisms behind this extreme event. Data from ground surface air pressure gauges, coastal tide gauges, underwater pressure gauges, infrasound sensors, digital microphones, and seismometers were collected. These data were analyzed to identify their origin and explain their interactions. The results of this study first present the detailed propagation characteristics of air pressure waves in the Taiwan region and verify the occurrence of a specific tsunami phenomenon caused by the atmospheric disturbance from the Tonga eruption. It follows a distinct mechanism, explaining its arrival time and wave height distribution around Taiwan, which is different from conventional tsunamis of tectonic origins, which are formed by rapid changes in water caused by earthquakes or underwater landslides. [ABSTRACT FROM AUTHOR]

The January 2022 eruption of Hunga Tonga‐Hunga Ha'apai (HTHH) injected a huge amount (∼150 Tg) of water vapor (H2O) into the stratosphere, along with small amount of SO2. An off‐line 3‐D chemical transport model (CTM) successfully reproduces the spread of the injected H2O through October 2023 as observed by the Microwave Limb Sounder. Dehydration in the 2023 Antarctic polar vortex caused the first substantial (∼20 Tg) removal of HTHH H2O from the stratosphere. The CTM indicates that this process will dominate removal of HTHH H2O for the coming years, giving an overall e‐folding timescale of 4 years; around 25 Tg of the injected H2O is predicted to still remain in the stratosphere by 2030. Following relatively low Antarctic column ozone in midwinter 2023 due to transport effects, additional springtime depletion due to H2O‐related chemistry was small and maximized at the vortex edge (10 DU in column). Plain Language Summary: Around 150 Tg (150 million tons) of water vapor was injected into the stratosphere during the eruption of Hunga Tonga‐Hunga Ha'apai. Water vapor is a greenhouse gas and this increase is expected to have a warming effect in the troposphere, as well causing perturbations in stratospheric chemistry and aerosols. We use an atmospheric model to study the residence time of this excess water vapor and its impact on the recent Antarctic ozone hole. The model performance is evaluated by comparison with satellite measurements. Wintertime dehydration in the Antarctic stratosphere in 2023 is found to be an important mechanism for removal of the volcanic water from the stratosphere. However, the overall removal rate is predicted to be slow; around 25 Tg (17%) is still present in 2030. The direct impact of the excess water vapor on ozone via chemical processes in the Antarctic ozone hole in 2023 is small. Key Points: Antarctic dehydration is a major removal pathway of stratospheric H2O injected from Hunga Tonga‐Hunga Ha'apai (HTHH) eruptionHTHH H2O caused small (up to 10 DU) additional chemical ozone depletion in 2023 Antarctic springModel indicates e‐folding timescale of 4 years for removal of HTHH H2O from stratosphere [ABSTRACT FROM AUTHOR]

Following the Hunga Tonga–Hunga Ha'apai (HTHH) eruption in January 2022, stratospheric ozone depletion was observed at Southern Hemisphere mid‐latitudes and over Antarctica during the 2022 austral wintertime and springtime, respectively. The eruption injected sulfur dioxide and unprecedented amounts of water vapor into the stratosphere. This work examines the chemistry contribution of the volcanic materials to ozone depletion using chemistry‐climate model simulations with nudged meteorology. Simulated 2022 ozone and nitrogen oxide (NOx = NO + NO2) anomalies show good agreement with satellite observations. We find that chemistry yields up to 4% ozone destruction at mid‐latitudes near ∼70 hPa in August and up to 20% ozone destruction over Antarctica near ∼80 hPa in October. Most of the ozone depletion is attributed to internal variability and dynamical changes forced by the eruption. Both the modeling and observations show a significant NOx reduction associated with the HTHH aerosol plume, indicating enhanced dinitrogen pentoxide hydrolysis on sulfate aerosol. Plain Language Summary: The January 2022 eruption of the Hunga Tonga‐Hunga Ha'apai underwater volcano injected a large amount of water vapor (H2O) and moderate amounts of sulfur dioxide (SO2) into the stratosphere. Stratospheric ozone depletion was observed following the eruption at Southern Hemisphere (SH) mid‐latitudes and over Antarctica during the 2022 austral wintertime and springtime, respectively. The ozone layer in the stratosphere protects both people and the biosphere by absorbing harmful solar ultraviolet radiation. We use computer simulation to examine the impacts of chemical processes on the ozone layer from the volcanic materials. We find that chemistry results in 4% and 20% of the ozone loss at SH mid‐latitudes near 70 hPa in August and Antarctica around 80 hPa in October respectively. Most of the ozone changes are due to transport and dynamical processes from internal variability in the climate system and a forced response by the HTHH eruption. Key Points: Chemistry yields 4% and 20% ozone depletion in the lower stratosphere at mid‐latitudes and Antarctica in August and October, respectivelyThe majority of ozone depletion is ascribed to internal variability and dynamical changes induced by the eruptionHTHH aerosol plume is associated with notable NOx reduction, indicating enhanced dinitrogen pentoxide hydrolysis on sulfate aerosol [ABSTRACT FROM AUTHOR]

We derive stratospheric aerosol microphysical parameters from Ozone Mapping Profiler Suite Limb Profiler (OMPS-LP) satellite measurements using aerosol extinction coefficient ratios at two wavelengths (the color ratio), which is sensitive to the particle radius, and concentration. We estimate various sources of uncertainty in this technique including extinction coefficient measurement error, sensitivity to the size distribution width assumption, and the OMPS-LP algorithm phase function error. We apply our algorithm to extinction coefficient measurements made by the Stratospheric Aerosol and Gas Experiment on the International Space Station (SAGE III/ISS) to verify our approach and find that our results are in good agreement. Our results also compare favorably to balloon borne particle size measurements and concentrations under ambient condition and 2019 Raikoke volcanic eruption assuming a log-normal particle size distribution width of 1.6. We also estimate the changes in aerosol median radius and concentration following the 2019 Raikoke and 2022 Hunga Tonga-Hunga Ha'apai volcanic eruptions and the result is consistent with other retrievals published in the literature. [ABSTRACT FROM AUTHOR]

A new algorithm was developed to infer particle size distribution parameters from the Stratospheric Aerosol and Gas Experiment II (SAGE II) and SAGE III on the International Space Station (SAGE III/ISS) extinction spectra using a lookup table (LUT) approach. Here, the SAGE-based extinction ratios were matched to LUT values, and, using these matches, weighted statistics were calculated to infer the median particle size distribution values and higher-moment parameters as well as quantify the uncertainty in these estimates. This was carried out by solving for both single-mode and bimodal lognormal distributions. The work presented herein falls under two general headings: (1) a theoretical study was carried out to determine the accuracy of this methodology, and (2) the solution algorithm was applied to the SAGE II and SAGE III/ISS records with a brief case study analysis of the 2022 Hunga Tonga eruption. This methodology was demonstrated to be ≈ 25 % accurate for mode radius and has a minor dependence on particle composition. While bimodal solutions were obtained from this algorithm, we provide a conclusive demonstration of how and why these estimates are inherently unstable using SAGE III/ISS extinction spectra alone. Finally, we demonstrated how the Hunga Tonga aerosol plume evolved in regard to both size and transport over 18 months after the 2022 Hunga Tonga eruption. The particle size distribution (PSD) estimates, higher-moment parameters, and uncertainties are new products within the SAGE III/ISS Level 2 (L2) products, are currently available for download, and will be merged into the main SAGE III/ISS release products in a subsequent L2 release. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the possible mechanism behind the volcanic plume drag and the massive expansion of the ionospheric Total Electron Content (TEC) along the eastern longitudes by using near-field observations of the 15 January 2022 Hunga Tong-Hunga Ha'apai volcanic eruption. The meteorological omega parameter shows a dominant upward/downward movement of the air parcels along the eastern and southern sides of the volcanic eruption. This dominant air convection under the presence of the heavy moisture of volcanic plume and vector winds indicated the formation of a cyclone over and around the Tonga volcano. This cyclone dragged the heavy volcanic plume towards the eastern longitudes (150oE – 180oE). Moreover, we observe that the volcanic plume injected about 5 DU of Sulfur Dioxide (SO 2) and 30 kgm−2 of the water content along the total atmospheric column. The chain reactions of Hunga Tonga volcanic trace gases with the gases present in the neutral atmosphere instigated an air ionization process, while under the presence of the heavy water content, these ions underwent an ion-hydration process that contributed to the electrodynamical changes in the region. These electrodynamical changes can be regarded as Atmospheric Chemical Potential (ACP) in the lower atmosphere. We observe a sharp increase in the ACP of ∼0.26 eV along the eastern longitudes (160–180°E) exactly above the dragged volcanic plume area. The long-term TEC changes that have been observed towards the eastern longitudes are the result of the ion-hydration process at the lower atmosphere. The statistical analysis showed a critical change during the day of the event up to ∼48 TECU with an increasing value of 28 and 18 TECU from the lowest and highest ranges before the event over the crater, respectively. Our main findings showed ionospheric anomalies in the near field started from 6:00 to 16:00 UTC. Based on Swarm satellites, the S4 values have significant changes around 0.3–0.6 lasting for tens of minutes. [ABSTRACT FROM AUTHOR]

The dual frequency Global Navigation Satellite System (GNSS) observations could determine the total electron content (TEC) in the ionosphere. In this study, GNSS TEC was applied to detect traveling ionospheric disturbances (TIDs) after the eruption of Hunga Tonga–Hunga Ha'apai (HTHH) on 15 January 2022. The eruption caused two types of tsunamis, first is tsunami generated by atmospheric wave (meteo‐tsunami) and second is caused by eruption induces water displacement or tsunami classic. At the same time with former tsunami, the atmospheric wave (shock and lamb waves) also caused TIDs at a speed of approximately ∼0.3 km/s. We found moderate correlation between this TIDs amplitude and the tsunami wave height model from tide gauge stations in New Zealand (0.64) and Australia (0.65). Further we attempted to reveal 3D structure of the TIDs in New Zealand, South Australia, and Philippines using 3D tomography. The tomography was set up > 1,170 blocks, as large as 1.0° (east–west) × 1.0° (north–south) × 100 km (vertical), up to 600 km altitude over selected regions. Tomogram shows beautiful concentric directivity of the first TIDs generated by atmospheric wave (AW). Key Points: 3D ionospheric disturbances during the 2022 Tonga eruption was investigated with spatial and temporal directionThe highest concentration of the electron disturbances was observed at an altitude of 200–300 km, which decreased at 500–600 kmA correlation between ionospheric disturbances and the height of tsunami associated with eruption was observed [ABSTRACT FROM AUTHOR]

We use high temporal‐resolution mesoscale imagery from the Geostationary Operational Environmental Satellite‐R (GOES‐R) series to track the Lamb and gravity waves generated by the 15 January 2022 Hunga Tonga‐Hunga Ha'apai eruption. The 1‐min cadence of these limited area (∼1,000×1,000 km2) brightness temperatures ensures an order of magnitude better temporal sampling than full‐disk imagery available at 10‐min or 15‐min cadence. The wave patterns are visualized in brightness temperature image differences, which represent the time derivative of the full waveform with the level of temporal aliasing being determined by the imaging cadence. Consequently, the mesoscale data highlight short‐period variations, while the full‐disk data capture the long‐period wave packet envelope. The full temperature anomaly waveform, however, can be reconstructed reasonably well from the mesoscale waveform derivatives. The reconstructed temperature anomaly waveform essentially traces the surface pressure anomaly waveform. The 1‐min imagery reveals waves with ∼40–80 km wavelengths, which trail the primary Lamb pulse emitted at ∼04:29 UTC. Their estimated propagation speed is ∼315 ± 15 m s−1, resulting in typical periods of 2.1–4.2 min. Weaker Lamb waves were also generated by the last major eruption at ∼08:40–08:45 UTC, which were, however, only identified in the near field but not in the far field. We also noted wind effects such as mean flow advection in the propagation of concentric gravity wave rings and observed gravity waves traveling near their theoretical maximum speed. Plain Language Summary: The record‐setting eruption of the Hunga Tonga‐Hunga Ha'apai volcano on 15 January 2022 was observed by geostationary satellites, which take an image of the full Earth disk every 10–15 min. Several smaller areas (∼1,000 km on a side) are, however, imaged every 1 min. The eruption generated various waves in the atmosphere, including acoustic waves traveling at the speed of sound and slower gravity waves. These atmospheric waves can be tracked by the subtle brightness temperature changes they cause in the images. We show that the 1‐min images used in our study capture finer details of the wave patterns and allow a better estimation of wave properties than the relatively infrequent full disk images. The high temporal frequency imagery also allows to determine the eruption sequence more precisely and reveal how the background winds affect the propagation of the waves. Key Points: Propagation of surface pressure anomalies explains the Lamb waveform derivative patterns seen in brightness temperature image differences1‐min mesoscale imagery depicts the short‐period variations within the long‐period wave packet envelope captured in full disk imageryThe Lamb wave train appears dispersive, main pulse is followed by waves with decreasing wavelength of ∼40–80 km and period of ∼2.1–4.2 min [ABSTRACT FROM AUTHOR]

A new retrieval algorithm to obtain vertical profiles of the aerosol extinction coefficient from the measurements of the scattered solar light in the limb viewing geometry made by the OMPS-LP instrument is presented. The method employs the normalization of the limb radiances to the solar irradiance in contrast to the normalization by a limb measurement at an upper tangent height, which is used by most of the other published limb-scatter retrievals. The main advantage of this approach is a nearly complete elimination of the dependence of the retrieval results on the prior aerosol extinction profile used in the retrieval. This makes the retrieval well suitable to analyze the observation scenes with highly elevated aerosol plumes as occurred after the Hunga Tonga–Hunga Ha'apai volcanic eruption in January 2022. The results from the new approach were compared to independent data from SAGE III/ISS and OSIRIS. In general, an agreement within 25% between the different data products was observed although larger differences were seen after very strong volcanic eruptions and wildfires. The new data product was used to investigate the evolution of the aerosol plume after the Hunga Tonga–Hunga Ha'apai volcanic eruption. [ABSTRACT FROM AUTHOR]

The devastation caused by the January 2022 eruption of Hunga Tonga-Hunga Ha'apai volcano (HTHH) in the Tongan archipelago reminded us of the importance of monitoring shallow-sea volcanic activity. Seismic observations are essential for such monitoring, but there were no operational seismic stations in Tonga at the time of the eruption. There are only a few islands near Tongan volcanoes, and installation and maintenance of seismic stations on remote islands are expensive. Seismic observations based on distributed acoustic sensing (DAS) using a seafloor cable may provide a more practical and economical solution. To investigate the potential of this approach, we made preliminary DAS observations for 1 week using the seafloor domestic broadband telecommunications cable in Tonga. DAS equipment was installed at the landing station of the seafloor cable at Nuku'alofa on Tongatapu, the main island of Tonga. To provide reference data, we installed several seismometers on Tongatapu. The DAS data we obtained showed high noise levels in areas of shallow coral reef, but noise levels decreased greatly in deeper water areas, indicating that DAS is suitable for seismic observations of the deep seafloor. We detected many local and regional earthquakes during our week of observation and determined 17 earthquake hypocenters by picking P- and S-wave arrival times from the DAS and onshore seismic data. Although most of these were tectonic events related to the subduction of the Pacific plate along the Tonga trench, several events were detected around the volcanic chain of the Tongan archipelago including one event beneath the HTHH crater, implying that activity at HTHH has continued since the 2022 eruption. The much lower cost of installation of DAS equipment compared to that for pop-up type ocean-bottom seismometers and the ability of DAS systems to monitor seismic activity in real-time make it an attractive option for monitoring the activity of HTHH and other volcanoes near seafloor cables in the Tongan archipelago. [ABSTRACT FROM AUTHOR]

The volcano of Hunga Tonga-Hunga Ha'apai in Tonga erupted on 15 January 2022, generating severe disturbances in the atmosphere and the ionosphere. This event provided us with large amount of data of the atmosphere and the ionosphere, and various kinds of observational studies have been made. Recently several simulation studies have also been made to reproduce and understand the atmosphere–ionosphere variations driven by the volcanic eruption. Although the simulation studies have reproduced the global variations of the atmosphere and the ionosphere successfully, phenomena related with acoustic waves have not been fully investigated. We employed an axisymmetric three-dimensional nonhydrostatic atmospheric model and the whole atmosphere–ionosphere coupled model GAIA. We found that the simulation can produce various kinds of atmospheric waves generated by the eruption, such as acoustic waves, gravity waves, Lamb waves, Pekeris waves, and TIDs concentrically propagating from the eruption site, and atmospheric oscillations with a period of a few minutes. In addition, the results indicate that the eruption generates supersonic shock waves in the volcanic region, leading to the extremely large vertical oscillations in the thermosphere and ionosphere above the volcanic eruption region. [ABSTRACT FROM AUTHOR]

The January 2022 eruption of the Hunga Tonga‐Hunga Ha'apai underwater volcano injected a large amount of water vapor into the mid‐stratosphere. This study uses model simulations to investigate the resulting stratospheric impacts out to 2031. Maximum radiatively‐driven model temperature changes occur in the Southern Hemisphere (SH) subtropics in April–May 2022, with warming of ∼1 K in the lower stratosphere and cooling of 3 K in the mid‐stratosphere. The radiative cooling combined with adiabatic cooling driven by the quasi‐biennial oscillation meridional circulation explains the near‐record cold anomaly observed in the SH subtropical mid‐stratosphere. Projected ozone responses maximize in 2023–2024 as the water vapor plume is transported globally throughout the stratosphere and mesosphere. The excess H2O increases the OH radical, causing a negative global ozone response (2%–10%) in the upper stratosphere and mesosphere due to increased odd hydrogen‐ozone loss, and a small positive ozone response (0.5%–1%) in the mid‐stratosphere due to interference of the NOx catalytic loss cycle by the additional OH. In the lower stratosphere, the excess H2O is projected to increase polar stratospheric clouds and springtime halogen‐ozone loss, enhancing the Antarctic ozone hole by 25–30 DU in 2023. Arctic impact is small, with maximum additional ozone loss of 4–5 DU projected in spring 2024. These responses diminish after 2024 to be quite small by 2031, as the excess H2O is removed from the stratosphere with a 2.5‐year e‐folding time. Given the year‐to‐year variability of the stratosphere, the magnitudes of these ozone responses may be below the threshold of detectability in observations. Plain Language Summary: Stratospheric ozone protects Earth's biosphere from harmful ultraviolet radiation, and along with water vapor, are key components in determining temperature and chemistry of the atmosphere. The January 2022 eruption of the Hunga Tonga‐Hunga Ha'apai underwater volcano in the South Pacific injected water vapor into the atmosphere, increasing stratospheric water vapor by 10%. In this study, we use computer simulations of the stratosphere to project how this additional water vapor changed temperature and ozone in the months and years following the eruption. The water vapor cooled the middle stratosphere (roughly 14–25 miles above Earth's surface) and warmed the lower stratosphere (6–14 miles above the surface), with the largest changes of 2–5° Fahrenheit in March–June 2022, several months after the eruption. The additional water vapor modified chemical processes that affect stratospheric ozone, leading to a projected 10%–15% enhancement in the Antarctic ozone hole. This ozone hole enhancement is estimated to have maximized in October 2023, almost 2 years after the eruption, due to the slow circulation of stratospheric water vapor from the subtropics to the polar region. These impacts are expected to diminish after 2024 as the excess water vapor is slowly removed from the atmosphere by natural processes. Key Points: The water vapor injection from the Hunga Tonga eruption impacts stratospheric temperature and ozoneLargest additional ozone depletion is estimated to occur in Antarctic spring 2023. The ozone response may not be detectable in observationsThe impacts are projected to gradually diminish after 2024 as the excess water vapor is removed from the stratosphere [ABSTRACT FROM AUTHOR]

Stratospheric sulfate aerosols play a key role on atmospheric chemistry and Earth's radiation budget, but their size distribution, a critical parameter in climate models, is generally poorly known. We address such gap for the 2022 Hunga Tonga–Hunga Ha'apai (HT–HH) volcanic eruption by exhaustively analyzing a set of satellite observations (TROPOMI, IASI, AHI, and CALIOP) together with photometric ground observations from the worldwide open‐access AERONET network. We document a rapid growth of HT–HH sulfate aerosols in the days following eruption, faster than observed for 1991 Pinatubo eruption, likely due to the exceptional hydration of the stratosphere by this phreatomagmatic eruption. An unusual aerosol fine mode (peak radius in 0.3–0.5 µm) is identified at 20 stations of the Southern Hemisphere until May 2023 (time of writing). Nevertheless, 1.4 years after eruption, HT–HH sulfate aerosols remain smaller than Pinatubo particles. Smaller aerosols backscatter more efficiently visible light and sediment more slowly than larger particles, implying stronger and longer‐lasting negative radiative forcing. Plain Language Summary: Explosive eruptions can inject large amounts of sulfate aerosols in the stratosphere, that may perturb atmospheric chemistry and Earth's climate. However, crucial information regarding the size of aerosols, a critical parameter in climate models, is generally missing. We address this gap for the eruption of Hunga Tonga–Hunga Ha'apai (HT–HH) in 2022, a record‐breaking eruption in the satellite era. Based on an exhaustive analysis of satellite observations together with photometric ground observations from the worldwide open‐access AERONET network, we document a rapid growth of HT–HH aerosols in the days following eruption. This early aerosol growth rate is faster than observed for 1991 Pinatubo, likely due to the exceptional humidification of the stratosphere caused by the water‐rich HT–HH eruption. Furthermore, the year‐long persistence of an unusually fine type of aerosols (i.e., with radius ∼0.4 μm) is identified at 20 stations of the Southern Hemisphere and used as a volcanic marker of the HT–HH plume. One year after eruption, and in spite of an initially rapid growth, HT–HH sulfate aerosols remain smaller than Pinatubo particles. Smaller particles better reflect sunlight and remain in suspension in the stratosphere for a longer time, fostering surface cooling. Key Points: In the days following eruption, Hunga Tonga sulfate aerosols are observed to grow faster than Pinatubo particlesHunga Tonga stratospheric aerosols persist for >14 months as identified at 20 AERONET stations of the Southern HemisphereOne year after eruption, Hunga Tonga aerosols remain smaller than Pinatubo particles, potentially implying an enhanced climate impact [ABSTRACT FROM AUTHOR]

A giant ionospheric hole was simultaneously detected in the in situ measurements of FORMOSAT-7/COSMIC-2 (F7/C2), Ionospheric Connection Explorer (ICON), Swarm missions, and ground-based total electron content (TEC) by global navigation satellite system receivers, and F7/C2 Global Ionosphere Specification (GIS) data near Tonga, following the explosive volcano eruption on 15 January 2022. The TEC maps displayed the huge depletions that developed near Tonga after the eruption and gradually evolved. The ICON IVM, F7/C2 IVM and Swarm-LP detected large depletions not only near Tonga, but also in the EIA trough region. The GIS observations clearly show the ionospheric hole that extends spatially near Tonga, especially strongly south/southward. The simultaneous observations showed that the ionosphere hole near Tonga combined with the EIA trough and finally evolved into a giant ionosphere hole around 07 UT. The ionospheric hole, which occurred at 05 UT near Tonga, extended over a wide area of 160°-200°E and 25°S-20°N and lasted for about 11 h. The F7/C2 and ICON satellites overpasses showed large ion density depletions by the hole at orbit altitudes, accompanied by enhancements in ion temperature and field-aligned and perpendicular ion drift. Such a long-lasting giant ionospheric hole by a seismic event has not been reported earlier, creating a unique ionospheric environment near Tonga after the eruption. The strong successive impulses by multiple volcano eruptions, together with O/N2 decrease in the summer hemisphere, interhemispheric wind, and water vapor injection into high altitudes apparently yielded such a giant ionospheric hole, 4–6 times larger than that observed during the Tohoku earthquake. Key points: The simultaneous measurements reveal the evolution of the ionospheric hole after the Tonga volcanic eruption. The ionospheric hole that had occurred near Tonga merged with the EIA trough depletion in the northern hemisphere, forming a giant ionospheric hole. The long-lasting giant ionospheric hole is caused by impulsive pressure, trans-equatorial wind, O/N2 depletion, and water vapor injection. [ABSTRACT FROM AUTHOR]

This article explores the development and training of national emergency medical teams (EMTs) in Pacific island countries and areas (PICs). The unique challenges faced by PICs, such as their remote locations and vulnerability to disasters and climate change, highlight the necessity of EMTs. The training program for Pacific EMTs is based on global standards but has been customized to suit the specific contexts of small Pacific islands. The program covers various areas, including administration, clinical care, and operational logistics, and incorporates hands-on activities and discussions. The article emphasizes the importance of preparedness for deploying mobile clinical response teams in PICs. [Extracted from the article]

Problem: The undersea Hunga Tonga-Hunga Ha'apai volcano erupted on 15 January 2022, causing a tsunami that affected Tonga as well as other countries around the Pacific rim. Tonga's international borders were closed at the time due to the coronavirus disease pandemic, but clinical surge support was needed to respond to this disaster. Context: Tonga's Ministry of Health formed the Tonga Emergency Medical Assistance Team (TEMAT) in 2018 to provide clinical care and public health assistance during disasters, outbreaks and other health emergencies. TEMAT was activated for the first time in January 2022 to respond to medical and public health needs following the eruption and tsunami. Action: On 16 January 2022, a five-person TEMAT advance team was deployed to conduct initial damage assessments and provide casualty care. Subsequently, TEMAT rotations were deployed to provide clinical care and public health support across the Ha'apai island group for over 2 months. Outcome: TEMAT deployed to the islands most affected by the volcanic eruption and tsunami within 24 hours of the event, providing emergency clinical, psychosocial and public health services across four islands. TEMAT reported daily to the Ministry of Health and National Emergency Management Office, providing critical information for response decision-making. All TEMAT actions were documented, and an after-action review was conducted following the deployment. Discussion: TEMAT's deployment in response to the 2022 volcanic eruption and tsunami highlighted the importance of national emergency medical teams that are prepared to respond to a range of emergency events. [ABSTRACT FROM AUTHOR]

This article provides an overview of the development and operations of emergency medical teams (EMTs) in Pacific island countries and areas. The World Health Organization (WHO) has been collaborating with member states and non-governmental organizations since 2010 to establish a network of deployable clinical rapid response teams. Pacific governments have invested in national response capacities, including the establishment of national EMTs, in response to natural disasters and disease outbreaks. These teams have received training and are now self-sufficient, capable of deploying to remote and challenging conditions. The article also highlights the expansion of EMT development to other Pacific island countries with support from various donor partners. Pacific EMTs have made significant progress since their establishment in 2017, with teams like FEMAT achieving international classification and being deployed for multiple national emergencies, including tropical cyclones and the COVID-19 response. Other teams, such as SOLMAT, TEMAT, and VANMAT, have also been deployed for various emergencies and outbreaks. These achievements demonstrate that even small and developing countries can develop and mobilize professional EMTs that can provide timely and high-quality responses to emergencies. The article emphasizes the opportunities for Pacific EMTs to further improve through training, research, and evaluation of their operations. The development of Pacific EMTs has been supported by various organizations and governments. [Extracted from the article]

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An undersea volcano at Hunga Tonga-Hunga Ha'apai (HTHH) near the South Pacific island nation of Tonga, erupted violently on 15 January 2022. Potential climate impact of the HTHH volcanic eruption is of great concern to the public; here, we intend to size up the impact of the HTHH eruption from a historical perspective. The influence of historical volcanic eruptions on the global climate are firstly reviewed, which are thought to have contributed to decreased surface temperature, increased stratospheric temperature, suppressed global water cycle, weakened monsoon circulation and El Niño-like sea surface temperature. Our understanding of the impacts of past volcanic eruptions on global-scale climate provides potential implication to evaluate the impact of the HTHH eruption. Based on historical simulations, we estimate that the current HTHH eruption with an intensity of 0.4 Tg SO2 injection will decrease the global mean surface temperature by only 0.004°C in the first year after eruption, which is within the amplitude of internal variability at the interannual time scale and thus not strong enough to have significant impacts on the global climate. [ABSTRACT FROM AUTHOR]

On 15 January 2022, the Hunga Tonga-Hunga Ha'apai (HTHH) (175.38° W, 20.54° S) volcano erupted explosively. It is considered the most explosive volcanic eruption during the past 140 years. The HTHH volcanic eruption caused intense ripples, Lamb waves, and gravity waves in the atmosphere which encircled the globe several times, as reported by different studies. In this study, using OMI, SAGE-III/ISS, and CALIPSO satellite observations, we investigated the spread of the volcanic SO2 cloud due to the HTHH eruption and subsequent formation of sulfuric acid clouds in the stratosphere. It took about 19–21 days for the stratospheric SO2 injections of the HTHH to encircle the globe longitudinally due to a dominant westward jet with wind speeds of ~2500 km/day, and it slowly dispersed over the whole globe within several months due to poleward spread. The formation of sulfuric acid clouds intensified after about a month, causing the more frequent occurrence of high aerosol optical depth elevated layers in the stratosphere at an altitude of about 20–26 km. This study deals with the dynamics of volcanic plume spread in the stratosphere, knowledge of which is essential in estimating the accurate radiative effects caused by perturbations in the earth–atmosphere system due to a volcanic eruption. In addition, this knowledge provides important input for studies related to the geo-engineering of the earth's atmosphere by injecting particulates and gases into the stratosphere. [ABSTRACT FROM AUTHOR]

The Hunga-Tonga volcanic eruption occurred on 15 January 2022 generated different modes of atmospheric and ionospheric waves. Using the Geostationary Operational Environment Satellite-17 (GOES-17), Aqua and Global Positioning System (GPS) satellite observations, an atmospheric and ionospheric multi-layer study of the Tonga volcano induced signatures over the New Zealand region is performed. The visible and infrared channel data of GOES-17 and Atmospheric Infrared Sounder (AIRS) data from NASA Aqua satellite confirm the presence of a highly convective zone and occurrence of concentric Lamb and gravity waves at lower atmospheric altitudes. The Total Electron Content (TEC) derived from 175 GPS stations covering the entire New Zealand region brings out two dominant modes of Travelling Ionospheric Disturbances (TIDs) having periodicity between 30 and 50 min. These two different modes having the phase speeds of 542 m/s and 354 m/s are allied to atmospheric gravity waves and Lamb wave triggered gravity waves respectively and are observed to propagate towards the south-west direction over the New Zealand region. [ABSTRACT FROM AUTHOR]

The 15 January 2022 eruption of the Hunga Tonga‐Hunga Ha'apai underwater volcano (20.5°S, 175.4°W) injected a record amount of water directly into the stratosphere. This study attempts to quantify this impact on the temperature, as well as the subsequent changes to the stratospheric circulation, during the months following the eruption based on reanalysis fields. The extreme nature of the temperature, wind, and circulation changes are tracked through comparisons of the first six months of 2022 with the previous 42 years. Examination of the data assimilation process shows that at 20 hPa the thermal observations are forcing significant cooling, compensating for the absence of the excess stratospheric moisture in the model used for the reanalysis. In response to this cooling the atmosphere adjusts by creating strong westerly winds above the temperature anomaly and large changes to the downward and poleward mean meridional circulation. Plain Language Summary: While the stratosphere (15–55 km) region of the atmosphere contains the ozone layer, it is typically very dry, especially when compared to the troposphere. However, the remarkable eruption of the Hunga Tonga‐Hunga Ha'apai underwater volcano on 15 January 2022 injected a record amount of water directly into the stratosphere. Winds in the stratospheric soon carried this excess water vapor around the globe to all longitudes and spread the water vapor in latitude as well. Since water vapor can cool to space more rapidly than the stratospheric air, enhanced cooling in the stratosphere is expected. This study quantifies this cooling, as well as the subsequent changes to the stratospheric circulation, during the months following the eruption. The extreme nature of the stratospheric temperature, wind, and circulation changes are tracked through comparisons of the first six months of 2022 with the previous 42 years. Details of the stratospheric perturbations in latitude and pressure are presented for June 2022, where anomalously low temperatures are found at near 20 km altitude from 60 to 30°S. In response to this cooling the atmosphere adjusts by creating strong westerly winds above the temperature anomaly and large changes to the downward and poleward mean meridional circulation. Key Points: Extreme perturbations in the stratospheric winds and temperatures are linked to a volcanic eruptionHunga Tonga‐Hunga Ha'apai eruption effects are unique in the stratospheric recordData assimilation can track temperature and wind perturbations, even when some physics is missing [ABSTRACT FROM AUTHOR]

The eruption of the Hunga-Tonga volcano in the South Pacific Ocean on January 15, 2022, at about 4:15 UTC, generated a violent explosion, which created atmospheric pressure disturbances in the form of Rayleigh-Lamb waves detected all over the globe. Here we discuss the observation of the Hunga-Tonga shock-wave performed at the Ny-Ålesund Research Station on the Spitsbergen island, by the detectors of the PolarquEEEst experiment and their ancillary sensors. Online pressure data as well as the results of dedicated offline analysis are presented and discussed in details. Results include wave arrival times, wave amplitude measurements and wave velocity calculation. We observed five passages of the shock wave with a significance larger than 3 σ and an amplitude up to 1 hPa. The average propagation velocity resulted to be (308 ± 0.6) m/s. Possible effects of the atmospheric pressure variation associated with the shock-wave multiple passages on the cosmic-ray rate at ground level are also investigated. We did not find any significant evidence of this effect. [ABSTRACT FROM AUTHOR]

Explosive volcanic eruptions can loft ash, gases, and water into the stratosphere, which affects both human activities and the climate. Using geostationary satellite images of the 15 January 2022 eruption of the Hunga Tonga-Hunga HaÕapai volcano, we find that the volcanic plume produced by this volcano reached an altitude of 57 kilometers at its highest extent. This places the plume in the lower mesosphere and provides observational evidence of a volcanic eruption injecting material through the stratosphere and directly into the mesosphere. We then discuss potential implications of this injection and suggest that the altitude reached by plumes from previous eruptions, such as the eruption of Mount Pinatubo in 1991, may have been underestimated because of a lack of observational data. [ABSTRACT FROM AUTHOR]

Meteotsunamis (forced waves) triggered by atmospheric disturbances of Lamb waves due to the 2022 Hunga–Tonga volcanic eruption have been observed in coastal areas surrounding the Pacific Ocean. However, the spatiotemporal evolution of the wavefield of meteotsunamis and meteotsunami-induced free waves remains elusive. Here, we show the detailed spatial distribution of the propagation velocities and directions of these waves in the bathymetric slope area between the Japan Trench and nearshore, using a dense array of 150 absolute pressure gauges deployed at water depths of 100–8000 m. Records show that free wave components (i.e., tsunamis) were generated when the forced wave was propagating over the slope area. Amplitudes of the generated free waves are large in the southern half of the slope area, where the equi-arrival time contour lines are densely paralleled. Such amplifications occur due to the relationship between the incoming direction of Lamb waves and the gradient of the bathymetric slope. This indicates that, if meteotsunamis excited by Lamb waves due to future volcanic eruptions come from different directions to this region, a different spatial pattern of free wave amplification on a regional scale is obtained in the bathymetric slope areas. [ABSTRACT FROM AUTHOR]

The eruption of Hunga-Tonga Volcano on January 15, 2022 has stimulated a wide spectrum of atmospheric waves globally. To probe the surface deformation pattern, Sentinel-1 Synthetic Aperture Radar (SAR) data has been analyzed. It has been approximated that an overall area of about 2.47 square kilometres experienced deformation in conjunction with this event. To characterize the atmospheric wave propagation, barometric pressure data from 1814 stations distributed all around the globe have been examined. This study encompassed with the propagation characteristics of the waves over four zones including Indian and Polar regions for the first time using barometric data. Time-series observations indicate that the waves propagated globally multiple times. Within the Indian region, three minor arc passages and one major arc passage were identified. In Japan, two minor arc passages and one major arc were present. Conversely, in North America, both minor and major arc passages were detected, occurring a minimum of three times. Moreover, the attributes of these waves, such as their propagation speed and periodicity, were compared across these four regions. The estimated phase speed and periodicity fall within the ranges of approximately 291–314 m/s and 10–180 min, respectively including Polar Regions. These speed and periodicity measurements of the observed waves suggest that the dominant mode of wave propagation generated during the Tonga volcanic eruption is that of Lamb waves. In addition, a slower propagation phase speed of about 226.6 m/s was identified in Japan which corresponds to Pekeris mode of waves. • Hunga-Tonga volcanic eruption triggered atmospheric waves that travelled globally in all direction multiple times. • Analysis of barometric data from India, Japan, North America and Polar Regions reveal the multi-wave characteristics of atmospheric waves. • The comparison of phase speed and periodicities are in the range ∼291–314 m/s and 45–50 min respectively. [ABSTRACT FROM AUTHOR]

The tsunami that occurred after the Hunga Tonga-Hunga Ha'apai volcano eruption on 15 January 2022 was unusually fast and large, particularly at large distances from the source. Here we use an observation-calibrated air-wave model to generate ocean waves using a tsunami model. We used pressure data observed at 94 stations in Niue, the Cook Islands, and New Zealand's main and outer islands to obtain a simple air-wave model. The modelled air-wave travels at an approximated constant speed of 317 m/s with an amplitude that decays with distance from the volcano. We then simulated the generation and propagation of tsunami due to the propagating air-wave in the atmosphere above the ocean. The leading sea surface displacement excited by the pressure disturbances travels at the same speed as the air-wave. This leading wave is then followed by subsequent water waves that travel in the same direction as the leading wave but at the conventional tsunami propagation speed. In the model, the air-wave was more effective at generating a tsunami when it travelled over a deep bathymetric feature like the Kermadec-Tonga Trench. The tsunami amplitudes observed at gauges do not decay as rapidly with distance from the volcano as would be expected for a localized tsunami source. This is due to the continuous excitation of the tsunami as the air-wave propagates across the ocean. In shallow water, the leading water surface displacement can often be much smaller than the later waves that were most likely to have been generated in the deep ocean. A better understanding of the complexity of tsunami generation and propagation of this kind is important to help improve future tsunami disaster mitigation from such sources. [ABSTRACT FROM AUTHOR]

Large volcanic eruptions, although rare events, can influence the chemistry and the dynamics of the stratosphere for several years after the eruption. Here we show that the eruption of the submarine volcano Hunga Tonga-Hunga HaÕapai on 15 January 2022 injected at least 50 teragrams of water vapor directly into the stratosphere. This event raised the amount of water vapor in the developing stratospheric plume by several orders of magnitude and possibly increased the amount of global stratospheric water vapor by more than 5%. This extraordinary eruption may have initiated an atmospheric response different from that of previous well-studied large volcanic eruptions. [ABSTRACT FROM AUTHOR]

On 15 January 2022 at 04:15 UTC, the Hunga Tonga-Hunga Ha'apai (HTHH) volcano in Tonga produced a massive eruption that triggered a transoceanic tsunami generated by the coupled ocean and atmospheric shock wave produced during the explosion. The tsunami first reached the coast of Tonga and eventually reached many coasts around the world. This volcano previously underwent a massive eruption in 1100 AD, and an eruption occurs approximately every 1000 years. The 2022 HTHH event provides an opportunity to study a major volcanically generated tsunami that caused substantial damage. In this study, we present a numerical simulation of a tsunami with a state-of-the-art numerical model based on a submarine explosion scenario. We constrain the geometry and magnitude of the explosion energy source based on analyses of pre- and post-event satellite images, which demonstrate that the explosion magnitude varied from 1 to 90 megatons of trinitrotoluene (Mt). Estimated submarine explosion geometries result in a suitable explosion magnitude of approximately 25 Mt, as determined with the waveform from the tide gauge in the time and frequency domains. The tsunami wave first reached the northwestern part of Tonga's Tongatapu within 10 min, with a maximum runup height of approximately 15 m, and covered the whole of Tongatapu within 30 min. Finally, the numerical simulation provides deep insights into the physical volcanic explosion processes and improves our understanding and forecasting capabilities of frequent and catastrophic tsunamis caused by submarine volcanic explosions. [ABSTRACT FROM AUTHOR]

On 20 December 2021, after six quiet years, the Hunga Tonga–Hunga Ha'apai volcano erupted abruptly. Then, on 15 January 2022, the largest eruption produced a plume well registered from satellites and destroyed the volcanic cone previously formed in 2015, connecting the two islands. We applied a multi-parametric and multi-layer study to investigate all the possible pre-eruption signals and effects of this volcanic activity in the lithosphere, atmosphere, and ionosphere. We focused our attention on: (a) seismological features considering the eruption in terms of an earthquake with equivalent energy released in the lithosphere; (b) atmospheric parameters, such as skin and air temperature, outgoing longwave radiation (OLR), cloud cover, relative humidity from climatological datasets; (c) varying magnetic field and electron density observed by ground magnetometers and satellites, even if the event was in the recovery phase of an intense geomagnetic storm. We found different precursors of this unique event in the lithosphere, as well as the effects due to the propagation of acoustic gravity and pressure waves and magnetic and electromagnetic coupling in the form of signals detected by ground stations and satellite data. All these parameters and their detailed investigation confirm the lithosphere–atmosphere–ionosphere coupling (LAIC) models introduced for natural hazards such as volcano eruptions and earthquakes. [ABSTRACT FROM AUTHOR]

On 15 January 2022, at around 04:00 UTC, the submarine volcano Hunga Tonga‐Hunga Ha'apai explosively erupted. We examine data from 10 Pacific Ocean geomagnetic observatories and process the data using both high pass filters and cross‐wavelet analyses to enable evaluating the time‐frequency characteristics of the magnetic signals across the Pacific region. At the Western Samoa observatory (API), magnetic signals of 3–8 min period, and visible in both vertical and horizontal fields, arrived at ∼04:44 UTC. The observatories at Chichijima Island (CBI) and Easter Island (IPM) both had local magnetic signatures concurrent with the eruption's water wave arrival and period ranges from, respectively, 13–93 and 5–100+ min. At CBI and IPM, the magnetic signal may be due to both the eruption's tsunami water wave and atmospheric/ionospheric sources. Our results suggest that the magnetic signatures from the eruption are identifiable and may be further separated in future studies. Plain Language Summary: On 15 January 2022, at around 04:00 UTC, the submarine volcano Hunga Tonga‐Hunga Ha'apai erupted in a violent explosion. Previous studies have identified magnetic signals from earthquake‐created tsunamis, however, no such studies have identified marine magnetic signals from eruption‐created tsunamis. Identifying magnetic signals from different aspects of a submarine eruption can lead to a better understanding of the eruption's mechanisms, as well as potentially improve warning systems for the tsunami created by the eruption. Toward this aim, we examine data from 10 Pacific Ocean geomagnetic observatories. We processed the data using mathematical methods that enable examining the different wave components of the timeseries. We find magnetic signals likely caused by the eruption at three different Pacific island observatories (API‐ Western Samoa, CBI‐ Chichijima Island, and IPM‐ Easter Island). Key Points: Magnetic signals of 3–8 min period, and visible in both horizontal and vertical field components, arrived at Western Samoa (API)Both Chichijima Island (CBI) and Easter Island (IPM) had local magnetic signatures concurrent with the eruption's water wave arrivalThe magnetic signals at CBI and IPM may be due to both the eruption's tsunami water wave and atmospheric/ionospheric waves [ABSTRACT FROM AUTHOR]

The devastating Hunga Tonga-Hunga Ha'apai underwater volcano erupted at ~04:15 UT on 15 January 2022. We captured the waves that erupted from the volcano propagating in the ionosphere by monitoring total electron content (TEC) perturbations utilizing ground-based global navigation satellite system (GNSS) receivers that receive electromagnetic signals transmitted from the geostationary satellites operated by the BeiDou Navigation Satellite System (BDS). Meanwhile, ground barometers detected unusual enhancements of air pressure traveling in the troposphere. A novel phenomenon shows that the waves can individually propagate with a speed of ~335 m/s in the ionosphere, which is faster than its' ~305 m/s in the troposphere. We further examined multiple geophysical data at the particular site of the novel instrumental array. Analytical results show that the pressure enhancements traveling in the troposphere not only downward trigger ground vibrations mainly in the horizontal components without obvious time difference, but also upward, leading the secondary TEC perturbations with a ~12-min delay. [ABSTRACT FROM AUTHOR]

The characteristics of acoustic-gravity waves (waveforms, time durations, amplitudes, azimuths and horizontal phase speeds) from the eruption of the Hunga-Tonga-Hunga-Hapai volcano detected at different infrasound stations of the Infrasound Monitoring System and at a network of low-frequency microbarographs in the Moscow region are studied. Using the correlation analysis of the signals at different locations, six arrivals of signals from the volcano, which made up to two revolutions around the Earth, were detected. The Lamb mode of acoustic gravity waves from the volcano eruption is identified and the effect of this mode on generation of tsunami waves and variation of aerosol concentration is studied. The energy released from an underwater volcano into the atmosphere is estimated from the parameters of the Lamb wave and compared with the energy released from the most powerful nuclear bomb of 58 Mt TNT. [ABSTRACT FROM AUTHOR]

• 2022 WSIS calving event was likely triggered by Hunga-Tonga volcanic tsunami. • A 74-year record underscores a pronounced escalation in WSIS instability post-2014. • A precondition for tsunami-induced ice shelf calving may be that the ice shelf pre-exists in an unstable condition. On January 15, 2022, the eruption of the Hunga-Tonga volcano unleashed a tsunami that rapidly traversed the Pacific Ocean, soon reaching the Sulzberger Ice Shelf (SIS), West Antarctica. In the aftermath, the West Sulzberger Ice Shelf (WSIS) experienced a significant calving event, shedding 106 km2 of ice and reducing its size to the smallest recorded since 1948. To investigate the potential association between this calving event and the tsunami, and to elucidate the long-term evolution of the WSIS, this study employed tide gage records and remote sensing data for an extensive cross-cycle observation spanning 74 years. The results indicate that post-2014, the WSIS exhibited heightened instability, manifesting as an increased frequency of calving events, a shift from an expanding to a contracting shelf area, and accelerated ice flow velocities (Video S1). The critical rift, instrumental in the 2022 calving, also displayed an accelerated widening rate post-2014, culminating in rapid expansion upon the tsunami's arrival, completing the final 2% of the iceberg's detachment boundary. Modeling results quantify the tsunami induced flexural strains on the ice shelf, with peak values occurring near the region of the subsequent calving event. Notably, multiple calving events during the study period coincided with local minima in landfast sea ice extent, underscoring its protective role for the ice shelf. Furthermore, a significant decline in landfast sea ice near the SIS had been observed over the past two decades, suggesting a weakening of this protective effect. A combination of modeling results and comparative analysis with other similar calving events suggests that tsunamis tend to expedite ice shelf calving predominantly when the shelf is already teetering on instability, which casts a shadow on the SIS's future resilience against natural hazards. [Display omitted] [ABSTRACT FROM AUTHOR]

The massive explosion by the January 15, 2022 Hunga Tonga-Hunga Ha'apai volcano in Tonga triggered a trans-oceanic tsunami generated by coupled ocean and atmospheric shock waves during the explosion. The tsunami reached first the coast of Tonga, and later many coasts around the world. The shock wave went around the globe, causing sea perturbations as far as the Caribbean and the Mediterranean seas. We present the effects of the January 15, 2022 Tonga tsunami on the Mexican Pacific Coast, Gulf of Mexico, and Mexican Caribbean coast, and discuss the underrated hazard caused by great volcanic explosions, and the role of early tsunami warning systems, in particular in Mexico. The shock wave took about 7.5 h to reach the coast of Mexico, located about 9000 km away from the volcano, and the signal lasted several hours, about 133 h (5.13 days). The shock wave was the only cause for sea alterations on the Gulf of Mexico and Caribbean Sea, while at the Mexican Pacific coast both shock wave and the triggered tsunami by the volcano eruption and collapse affected this coast. The first tsunami waves recorded on the Mexican Pacific coast arrived around 12:35 on January 15, at the Lázaro Cárdenas, Michoacán tide gauge station. The maximum tsunami height exceeded 2 m at the Ensenada, Baja California, and Manzanillo, Colima, tide gauge stations. Most tsunami warning advisories, with two exceptions, reached communities via social media (Twitter and Facebook), but did not clearly state that people must stay away from the shore. We suggest that, although no casualties were reported in Mexico, tsunami warning advisories of far-field tsunamis and those triggered non-seismic sources, such as landslides and volcanic eruptions, should be included and improved to reach coastal communities timely, explaining the associated hazards on the coast. [ABSTRACT FROM AUTHOR]

Atmospheric pressure and sea level records recorded in tidal observatories along the Pacific Coast of Mexico and in the Deep-Ocean Assessment and Reporting of Tsunami (DART Station 43412) SW of Manzanillo are used to investigate the mechanism of this complex tsunami that produced wave heights in bays and harbors as high as the wave heights produced by large far-field tsunamis. The term complex tsunami is coined here as a tsunami composed of sea surface reverberation—produced by the footprint of the atmospheric shock wave during its propagation through the oceans—and of the tsunami—produced by the atmospheric pressure footprint around the Hunga-Tonga volcano, and by the submarine part of the volcano explosion—both coupled trough harbor resonance. An amplitude damping function for the atmospheric shock wave is investigated here to improve tsunami warnings due to volcanic eruptions, in the sense that complex tsunamis may produce significant harbor resonance in well-known tsunami responsive harbors. The atmospheric pressure footprint during the volcanic eruption around the Hunga-Tonga volcano is estimated here of 40 millibars (mb), through the inverse damping function. [ABSTRACT FROM AUTHOR]

On 15 January 2022, around 4:30 UTC the eruption of the Hunga‐Tonga volcano, in the South Pacific Ocean, generated a violent underwater explosion. In addition to tsunami waves that affected the Pacific coasts, the eruption created atmospheric pressure disturbances that spread out in the form of Lamb waves. The associated atmospheric pressure oscillations were detected in high‐frequency in‐situ observations all over the globe. Here we take advantage of the similarities in the propagation and characteristics between atmospheric Lamb waves and long ocean waves and we use a 2DH ocean numerical model to simulate the phenomenon. We compare the outputs of the numerical simulation with in‐situ atmospheric pressure records and with remote satellite observations. The signal in the model matches the observed atmospheric pressure perturbations and reveals an excellent agreement in the wave arrival time between model and observations at hundreds of locations at different distances from the origin. Plain Language Summary: The underwater explosion of the Hunga‐Tonga volcano in the South Pacific Ocean generated atmospheric pressure disturbances, known as Lamb waves, that propagated and surrounded the globe several times. In this study, we exploit the similarities between atmospheric Lamb waves and long waves in the ocean (e.g., tsunamis) to simulate their propagation using an ocean numerical model. The comparison of our results with remote satellite data and in‐situ atmospheric pressure records reveals that our model correctly reproduces the propagation of the atmospheric disturbances generated by the volcano explosion. Key Points: The underwater Hunga‐Tonga volcano exploded generating Lamb waves that traveled around the Earth several timesWe simulate these waves using a hydrostatic shallow water equation oceanic modelThe results closely follow the observations of atmospheric pressure perturbations [ABSTRACT FROM AUTHOR]

On 15 January 2022, the volcano Hunga Tonga about 8000-km away from Japan explosively erupted. Following the eruption, tsunami-like sea-level fluctuations were observed in Japan, much earlier than expected based on the oceanic long-wave propagation from Tonga. By contrast, atmospheric pressure disturbance presumably due to the eruption was also observed about 30 minutes before the sea-level change. Therefore, the observed sea-level fluctuations can be considered as meteotsunamis forced by the pressure perturbation rather than tectonically forced by the eruption, but the mechanism is not yet fully understood. This study attempts to understand the nature of this meteotsunami by using a simple one-dimensional shallow-water model. The results show that the time and amplitude of the observed sea-level changes are consistent with the simulated sea-level changes forced by the atmospheric forcing. A set of experiments with different bathymetry profiles also reveals the importance of amplification due to near-Proudman resonance over deep basins and the shoaling effect over the continental slope, while extremely deep and narrow topography such as trenches is of second-order importance. [ABSTRACT FROM AUTHOR]

Extreme events affect societies all around the world. A recent example is the submarine volcano Hunga Tonga- Hunga Ha'apai in the South Pacific Ocean, which erupted on January 15, 2022 at approximately 0415 UTC, expelling ash up to 39 kilometers high. Instruments around the world recorded both the initial atmospheric shock wave and the subsequent tsunami signal. The aim of this work is to report the record from tide gauges and barometers of this event along the Brazilian coast. For this, the tsunami travel time to Brazil was calculated, and spikes in atmospheric pressure data and noise in the tide gauge records were identified. The arrival of the tsunami waves was clearly observed in tidal records from three stations located in Imbituba, Arraial do Cabo, and Salvador. In addition, in Belém and Santana, the signal-to-noise ratio was too low or there was no signal at all. Surprisingly, the atmospheric signal was less observable. The shock wave signature was evident in the Fortaleza atmospheric pressure data, while at the Imbituba and Belém stations the signal only appeared after filtering the data by calculating the highest and lowest pressure difference within the hour. The weaker, or absence of, barometric signal is likely associated with the supposed attenuation, or blocking, of the signal by the Andes Mountains. [ABSTRACT FROM AUTHOR]

According to a report from the European Union's Copernicus Climate Change Service, 2023 was the hottest year on record, with average surface temperatures rising nearly 0.2°C above the previous record set in 2016. The spike in temperatures was unexpected and cannot be solely attributed to the burning of fossil fuels. Factors such as the end of a La Niña climate pattern and a decrease in light-blocking pollution may have contributed to the record-breaking temperatures. However, the exact cause of the spike remains a mystery. Despite uncertainties about future projections, the long-term warming trend is expected to continue until fossil fuel burning is halted. [Extracted from the article]