We present a climatological study of aerosols in four representative islands’ stations of the Caribbean based on daily mean values of aerosol optical properties for the period 2008-2016. A daily classification of the dominant aerosol type is carried out, exploring the long-term transport of the main types of aerosols from different sources. All stations show a marked annual cycle in aerosol properties. Maximum values of Aerosol Optical Depth occur in summer, coinciding with the annual minimum in the Ångström Exponent and an increased occurrence of dust. The opposite behavior is observed in winter, due to the predominance of marine aerosols. Marine and dust aerosols are more frequent in the easternmost islands of the Caribbean, and decrease westwards due to an increasing presence of continental and mixture dust aerosols. As a consequence, the westernmost station of Camagüey displays the most heterogeneous composition of aerosols. Backward trajectories indicate that winter marine aerosols and summer dust are transported by air parcels travelling within the tropical easterly winds. The main source region of both types of aerosols is the subtropical eastern Atlantic, with the exception of Cuba, where the largest contributor to winter marine aerosols is the subtropical western Atlantic. These preferred pathways can occur under relatively weak and/or diverse synoptic patterns, typically involving transient systems and specific configurations of the Azores High that depend on the considered station.

Biomass burning is an important source of trace gases and particles, and can influence air quality on local, regional, and global scales. With the threat of wildfire events increasing due to changes in land use, increasing population, and climate change, the importance of characterizing wildfire emissions is vital. In this work we characterize trace gas emissions from 12 wildfires and 1 prescribed fire in California between 2013 and 2017, in some cases with multiple measurements performed during different burn periods of a specific fire. Airborne measurements of carbon dioxide, methane, ozone, formaldehyde, water vapor, temperature and 3-dimensional winds were made by the Alpha Jet Atmospheric eXperiment (AJAX) and [has been/will soon be] published at NASA’s Airborne Science Data Center (doi:10.5067/ASDC/AJAX/wildfire). The majority of these measurements were made as close as possible to each fire and represent fresh emissions from known fire sources. This set of observations from 13 different fires offers the opportunity to explore trace gas emissions over a range of meteorology, fire conditions, and to a lesser extent, vegetation type and drought, and adds to the body of knowledge collected by other investigators and field campaigns.

This study separates the dry and wet components of the moist isentropic mass circulation (MIMC) on daily timescale and investigates their relationships with extratropical surface temperature changes in winter. Results derived from ERA5 reanalysis data (1979-2018) show that, the MIMC is composed of a poleward warm branch (WB) in upper layers, which is dominated by the wet component in mid-latitude troposphere but by the dry component to the rest, and an equatorward cold branch below, dominated by the dry component. The stronger wet component of WB in 50-70N (WB_W) is a better precursory indicator than the dry component (WB_D) for the Arctic surface warming in winter, because of its dominant role in modifying the downward longwave radiation via water vapor-related processes. The stronger WB_D is coupled with negative Arctic Oscillation and a stronger equatorward transport of colder air, thus a better precursor for the cold events in the mid-latitudes.

Squall lines are known to be the consequence of the interaction of low-level shear with cold pools associated with convective downdrafts. Also, as the magnitude of the shear increases beyond a critical shear, squall lines tend to orient themselves at an angle to the shear. The existing literature suggests that this angle conserves the projection of the shear on the direction perpendicular to the squall line. However, this hypothesis has never been clearly demonstrated. Here, we confront this theory with tropical squall lines obtained by imposing a vertical wind shear in cloud resolving simulations in radiative convective equilibrium. In the sub-critical regime, squall lines are indeed perpendicular to the shear. In the super-critical regime, their orientation optimizes the projection of the background shear, which supports existing theories. We also find that as shear increases, cold pools become more intense. However, this intensification has little impact on the squall line orientation.

Temperature proxies such as clumped isotope (Δ47) thermometry on biogenic carbonates are applied to the past with greatest confidence when the proxy-temperature relationship is shown to be robust within natural temperature conditions of the ocean. Especially well-suited for this purpose are biogenic carbonates sampled from well-constrained production period and oceanographic conditions of sediment traps. Since coccolithophorids have a cosmopolitan distribution and are major biogenic carbonate producers in the surface ocean, their coccoliths usually dominate the inorganic carbon flux in sediment traps and are sufficiently abundant in most traps for clumped isotope analysis. Here, we measured Δ47 in the coccolith size fraction of 18 sediment trap samples across a 75° latitudinal gradient and three ocean basins. To identify the upper ocean provenance region of the coccoliths in each trap, a simple model of coccolith transport by ocean currents was constructed. The coccolith Δ47 strongly follows the upper ocean temperatures, in particular the average temperatures from the maximum production depths of living coccolithophores from their provenance areas. There is no evidence for a coccolithophore species-specific effect on the Δ47-temperature relationship. Applying the recent coccolith-specific Δ47-temperature calibration (Clark et al., 2024a) to estimate calcification temperatures shows that inferred calcification depths match the depth of maximum coccolithophore production in the provenance area. Compared to other calibrations for biogenic carbonates, the coccolith-specific Δ47-temperature calibration yields the best agreement with the depth of maximum coccolithophore abundance and the expected depth of coccolith production.

Dust is an important and complex constituent of the atmospheric system, having significant impacts on the environment, climate, air quality, and human health. Although dust events are common across many regions of the United States, their impacts are not often prioritized in air quality mitigation strategies. We argue that there are at least three factors that result in underestimation of the social and environmental impact of dust events, making them receive less attention. These include (1) sparse monitoring stations with irregular spatial distribution in dust-influenced regions, (2) inconsistency with dust sampling methods, and (3) sampling frequency and schedules, which can lead to missed dust events or underestimation of dust particle concentrations. Without addressing these three factors, it is challenging to characterize and understand the full air quality impacts of dust events in the United States. This paper highlights the need for additional monitoring to measure these events so that we can more fully evaluate and understand their impacts, as they are predicted to increase with climate change.

A new model of fault structure in the active New Madrid Seismic Zone (NMSZ) is presented based on relocated hypocenters and application of a statistical clustering method to determine fault planes. Over 200 earthquakes are recorded in the NMSZ every year, but the three-dimensional (3-D) fault structure is difficult to determine because the zone is covered by thick, Mississippi Embayment sediment. The distribution of earthquakes in the NMSZ indicates four major arms of seismicity, suggesting the presence of a northeast-southwest trending strike-slip fault system with a major northwest trending, contractional stepover fault. The most seismogenic faults are the strike-slip Axial fault and the Reelfoot thrust fault. Developing an accurate, 3-D fault model is important for dynamic modeling of the fault system and better specification of the seismic hazard. We relocated 4131 hypocenters for earthquakes occurring between 2000 and 2019 using the HypoDD double difference relocation technique. HypoDD is appropriate for the NMSZ because the earthquakes are tightly clustered, and the network stations are dense. The Optimal Anisotropic Dynamic Clustering technique is used to develop the fault structure for the NMSZ using the relocated hypocenters. The Reelfoot fault is continuous along strike from the northern end to the Ridgely fault, located south of the intersection with the Axial fault. The strike-slip arms are well resolved and correspond to near vertical planes. Three planes are resolved in the southern part of the Axial fault and are associated with the Osceola intrusive complex.

Using borehole strainmeters, we detected a 13-day long slow slip event on the Longitudinal Valley Fault, Taiwan. It is located between 8 to 15 km depth and has an equivalent moment magnitude of 5.5. The slow event has likely been promoted by the significant Coulomb stress changes (∼ + 1 MPa) imparted by a combination of coseismic and postseismic slip of the M w 6.8 Chengkung earthquake. Besides, insignificant coseismic slip is observed in the slow event region, suggesting that the latter could have acted as a barrier during the Chengkung earthquake. We also found a spatiotemporal correlation between the slow event and a cluster of repeating microearthquakes, suggesting aseismic slip as a possible driven mechanism of repeating ruptures. These results highlight the complex interplay between seismic and aseismic processes along the fault.

The threat of nuclear winter from a regional nuclear war is an existential hazard that must be addressed to ensure the shared future of humanity. Here a cross-cultural analysis of 20 societies that experienced the Late Antique Little Ice Age (ca. 536-556CE) is performed. The climatic conditions of the Late Antique Little Ice Age are strikingly similar to those modeled as resulting from a regional nuclear war employing low-yield nuclear weapons, and thus provides a context in which mechanisms of resilience to nuclear winter might be empirically identified. It is argued that broad political participation fostering bridging ties between communities, agencies, and organizations was a key elements of social resilience to the Late Antique Little Ice Age, and may indicate a means to foster resilience to nuclear winter today.

LST is routinely retrieved from the GOES-R Advanced Baseline Imager (ABI) long wave spectral channels. Since the product is available only under clear sky conditions, large gaps exist in the data stream which correspond to contamination by clouds. However, continuous estimates of LST data are still vitally needed for several applications such as drought monitoring ,vegetation growth, and crop yield estimation etc. Studies have shown that LST tracks with corresponding changes in incident solar radiation or more specifically changes in surface absorbed solar radiation with good correlation irrespective of sky conditions (clear or cloudy). In the present study, a scheme is developed to fill in the large spatio-temporal gaps in the LST time series using surface solar absorption parameter (SSA) retrieved in near real time from other satellites. Validation of retrieved LST values over all of the SURFRAD stations reveal RMS errors of less than 1 K.

In July 2021, Germany experienced its costliest riverine floods in history, with over 189 fatalities and a staggering \euro33 billion in damages. Following this event, news outlets widely disseminated information on the flood’s aftermath. Here, we demonstrate how newspaper data can be instrumental in the assessment of flood socioeconomic impacts often overlooked by conventional methods. Using natural language processing tools on 14,888 unique newspaper articles, we estimate the impacts of the 2021 flood on various sectors and critical infrastructure, including water contamination, mental health, and tourism. Our results revealed severe and lasting impacts in the Ahr Valley, even months after the event. At the same time, we identified smaller-scale yet widespread impacts across Germany, which are typically overlooked by existing impact databases. Our approach advances current research by systematically examining indirect and intangible flood impacts over large areas. This underscores the value of leveraging complementary text data to provide a more comprehensive picture of flood impacts.

Climate and weather extremes such as heat waves, droughts, extreme precipitation events or cold surges have huge social and economic impacts that are expected to increase with climate change. Forecasting of such extreme events on the sub-seasonal time scale (from 10 days to about 3 months) is very challenging because of the poor understanding of phenomena that may increase predictability at this time scale. The Madden-Julian Oscillation (MJO) is the dominant mode of variability in the tropical atmosphere on sub-seasonal time scales and can also promote or enhance phenomena such as monsoons and hurricanes in other regions of the world. Here we develop artificial neural networks that can lead to a very competitive MJO prediction. While our average prediction skill is about 26-27 days (which competes with that obtained with computationally demanding state-of-the-art climate models), for some initial phases the methodology has a prediction skill of 60 days or longer.

Flow through partially frozen pores in granular media containing ice or gas hydrate plays an essential role in diverse phenomena including methane migration and frost heave. As freezing progresses, the frozen phase grows in the pore space and constricts flow paths so that the permeability decreases. Previous works have measured the relationship between permeability and volumetric fraction of the frozen phase, and various correlations have been proposed to predict permeability change in hydrology and the oil industry. However, predictions from different formulae can differ by orders of magnitude, causing great uncertainty in modeling results. We present a floating random walk method to approximate the porous flow field and estimate the effective permeability in isotropic granular media, without solving for the entire flow field in the pore space. In packed spherical particles, the method compares favorably with the Kozeny-Carman formula. We further extend this method with a probabilistic interpretation of the volumetric fraction of the frozen phase, simulate the effect of freezing in irregular pores, and predict the evolution of permeability. Our results can provide insight into the coupling between phase transitions and permeability change, which plays important roles in hydrate formation and dissociation, as well as in the thawing and freezing of permafrost and ice--bed coupling beneath glaciers.

A document by Raymond Donelick. Click on the document to view its contents.

This study analyzes hydrometeor evolution during rapid intensification (RI) and tropical cyclone (TC) intensity dependence using satellite data. Previous studies have suggested that ice cloud water or non-convective precipitation can serve as predictors of RI from different perspectives. However, few studies have focused on the impact of TC intensity or comprehensive comparisons to identify better indicators. During RI, the hydrometeor contents in weak TCs (WTCs) increase over the entire region, whereas they increase mainly in the inner-core region and decrease in advance in the outer-core region for strong TCs (STCs). Hydrometeor contents are higher in RI than in slow intensification, and their maximum locations are related to TC intensity and intensification rate. Cloud water content (CWC) in the inner-core region has the largest correlation with the intensification rate, especially in WTCs. Therefore, the CWC can serve as a predictor of RI and can be applied to all TC intensities.

We developed an eruption forecasting model using data from multiple sensors or data streams with the Bayesian Network method. The model generates probabilistic forecasts that are interpretable and resilient against sensor outage. We applied the model at Whakaari/White Island, an andesite island volcano off the coast of New Zealand, using seismic tremor recordings, earthquake rate, and CO2, SO2, and H2S emission rates. At Whakaari/White Island, our model shows increases in eruption probability months to weeks prior to the three explosive eruptions that were recorded since 2012. We also observe that explosive eruptions consistently occurred after the cumulative probability exceeded at least 80%. Although developed for Whakaari/White Island, our model can be easily adapted to other volcanoes, complementing existing forecasting methods that rely on single data streams.

Accurate modeling of Jupiter’s magnetospheric magnetic field is important for not only scientific research but also mission planning. We develop a new empirical global model of Jupiter’s magnetic field in the Juno era, including components from the planetary dynamo, Chapman-Ferraro currents, and cross-tail current sheet. The internal field is based on the JRM09 model. The shielding field is obtained by minimizing the component normal to Jupiter’s magnetopause and varies due to the change of solar wind dynamic pressure. Combined with the curved magnetodisk, the high-resolution TS07 method is used for modeling Jupiter’s magnetodisc and tail currents. The best-fitting results show an asymmetric magnetodisc current system in azimuthal direction with a tilted angle to Jupiter’s magnetic equator. The sweep-back effects of Jupiter’s magnetic fields are also reproduced by the radial current system. This new model is validated by comparing with Juno’s magnetometer data in the range from 5 Rj to 60 Rj, where Rj=71492 km is the radius of Jupiter.

Highlights • We refined the seismic stratigraphic framework for the upper continental slope interfan region between the Kongsfjorden and Isfjorden Trough Mouth Fans.