In atmospheric modeling, superparameterization has gained popularity as a technique to improve cloud and convection representations in large scale models by coupling them locally to cloud-resolving models. We show how the different representations of cloud water in the local and the global models in superparameterization lead to a suppression of cloud advection and ultimately to a systematic underrepresentation of the cloud amount in the large scale model. We demonstrate this phenomenon in a regional superparameterization experiment with the global model OpenIFS coupled to the local model DALES (the Dutch Atmospheric Large Eddy Simulation), as well as in an idealized setup, where the large-scale model is replaced by a simple advection scheme. To mitigate the problem of suppressed cloud advection, we propose a scheme where the spatial variability of the local model’s total water content is enhanced in order to achieve the correct cloud condensate amount.

Volcano deformation monitoring is fundamental to detect pressurizations of magma bodies and forecasting any ensuing eruptions. Analytical and quasi-analytical solutions for pressurized cavities are routinely used to constrain volcano deformation sources through inversion of surface displacement data. Due to their computational efficiency, such solutions enable a thorough exploration of the parameter space and thereby provide insight into the physics of magma-rock interaction. Developing more general deformation models can help us better characterize subsurface magma storage. We develop quasi-analytical solutions for the surface deformation field due to the pressurization of a finite (triaxial) ellipsoidal cavity in a half-space. The solution is in the form of a non-uniform distribution of triaxial point sources within the cavity. The point sources have the same aspect ratio, determined by the cavity shape, while their strengths and spacing are determined in an adaptive manner, such that the net point-source potency per unit volume is uniform. We validate and compare our solution with analytical and numerical solutions. We provide computationally-efficient MATLAB codes tailored for source inversions. This solution opens the possibility of exploring the geometry of shallow magma chambers for potential deviations from axial symmetry.

GPS observations of ocean tide loading displacements can help infer the regional anelastic properties of the asthenosphere. We estimate M2 ocean tide loading displacements at 170 GPS sites in New Zealand and compare these to modeled values using a range of numerical tide and radially symmetric (1D) elastic and anelastic Earth models. Regardless of the model combination we are unable to reduce the strong spatial coherence of the M2 residuals across the North Island where they reach 0.4 mm (2%). The best fit in the North Island is obtained when combining the FES2014b tide model with spatially-variable ocean density and water compressibility, and the STW105 Earth model. The residuals exhibit a change of ~0.3 mm in magnitude between the Taupo Volcanic Zone and the east coast (~100 km), suggesting that this region’s laterally-varying, shallow rheological structure may need to be considered to explain these observations.

Gravity fluctuations produced by ambient seismic fields are predicted to limit the sensitivity of the next-generation, gravitational-wave detector Einstein Telescope at frequencies below 20 Hz. The detector will be hosted in an underground infrastructure to reduce seismic disturbances and associated gravity fluctuations. Additional mitigation might be required by monitoring the seismic field and using the data to estimate the associated gravity fluctuations and to subtract the estimate from the detector data, a technique called coherent noise cancellation. In this paper, we present a calculation of correlations between surface displacement of a seismic field and the associated gravitational fluctuations using the spectral-element SPECFEM3D Cartesian software. The model takes into account the local topography at a candidate site of the Einstein Telescope at Sardinia. This paper is a first demonstration of SPECFEM3D's capabilities to provide estimates of gravitoelastic correlations, which are required for an optimized deployment of seismometers for gravity-noise cancellation.

Volcanogenic tsunami and wave hazard remains less understood than that of other tsunami sources. Volcanoes can generate waves in a multitude of ways, including subaqueous explosions. Recent events, including a highly explosive eruption at Hunga Tonga-Hunga Ha’apai and subsequent tsunami in January 2022, have reinforced the necessity to explore and quantify volcanic tsunami sources. We utilise a non-hydrostatic multilayer numerical method to simulate 20 scenarios of sublacustrine explosive eruptions under Lake Taupō, New Zealand, across five locations and four eruption sizes. Waves propagate around the entire lake within 15 minutes, and there is a minimum explosive size required to generate significant waves (positive amplitudes incident on foreshore of >1 m) from the impulsive displacement of water from the eruption itself. This corresponds to a mass eruption rate of 5.8x10^7 kg s^-1, or VEI 5 equivalent. Inundation is mapped across five built areas and becomes significant near shore when considering only the two largest sizes, above VEI 5, which preferentially impact areas of low-gradient run-up. In addition, novel hydrographic output is produced showing the impact of incident waves on the Waikato river inlet draining the lake, and is potentially useful for future structural impact analysis. Waves generated from these explosive source types are highly dispersive, resulting in hazard rapidly diminishing with distance from the source. With improved computational efficiency, a probabilistic study could be formulated and other, potentially more significant, volcanic source mechanisms should be investigated.

Using the method of process-oriented hydrodynamic modelling, this work investigates the dispersal of particles in stratified fluids on continental margins. The focus is placed on steady-state density distributions that are governed by an advective-diffusive balance. In this case, particles can still be advected across isopycnal surfaces, given that turbulent fluctuations do generally not offset the advective displacement of a particle. The validity of this fundamental principle is demonstrated here with the diapycnal upslope sediment transport in a bottom Ekman layer that forms under a stratified geostrophic slope current. Similarly, this study demonstrates that interaction between slope currents with a submarine channel can facilitate a continuous diapycnal upslope flux of particles, confined to the lowermost 10-20 m of the water column. Velocity anomalies that facilitate this upslope sediment flux are the signature of standing topographic Rossby waves, that can only develop for slope currents that are left-bounded (right-bounded) by shallower water in the northern (southern) hemisphere. Findings of sensitivity studies confirm the existence of up-channel flows for a wide range of parameter values. Under the assumption that particles remain suspended in the water column, the inclusion of gravitational settling significantly increases the up-channel sediment flux. Sediment settling operates to trap particles close to the seafloor within the core of bottom-intensified up-channel flow. The author postulates that this mechanism plays an important role in biogeochemical cycles at continental margins.

The forecasting of local GIC effects has largely relied on the forecasting of dB/dt as a proxy and, to date, little attention has been paid to directly forecasting the geoelectric field or GICs themselves. We approach this problem with machine learning tools, specifically recurrent neural networks or LSTMs by taking solar wind observations as input and training the models to predict two different kinds of output: first, the geoelectric field components Ex and Ey; and second, the GICs in specific substations in Austria. The training is carried out on the geoelectric field and GICs modelled from 26 years of one-minute geomagnetic field measurements, and results are compared to GIC measurements from recent years. The GICs are generally predicted better by an LSTM trained on values from a specific substation, but only a fraction of the largest GICs are correctly predicted. This model had a correlation with measurements of around 0.6, and a root-mean-square error of 0.7 A. The probability of detecting mild activity in GICs is around 50%, and 15% for larger GICs.

The Indo-Gangetic Plain (IGP) is one of the dominant sources of air pollution worldwide. During winter, the variations in planetary boundary layer (PBL) height, driven by a strong radiative thermal inversion, affect the regional air pollution dispersion. To date, measurements of aerosol-water vapour interactions, especially cloud condensation nuclei (CCN) activity, are limited in the Indian sub-continent, causing large uncertainties in the radiative forcing estimates of aerosol-cloud interactions. We present the results of a one-month field campaign (February-March 2018) in the megacity, Delhi, a significant polluter in the IGP. We measured the composition of fine particulate matter (PM1) and size-resolved CCN properties over a wide range of water vapour supersaturations. The analysis includes PBL modelling, backward trajectories, and fire spots to elucidate the influence of PBL and air mass origins on the aerosols. The aerosol properties depended strongly on the PBL height, and a simple power-law fit could parameterize the observed correlations of PM1 mass, aerosol particle number, and CCN number with PBL height, indicating PBL induced changes in aerosol accumulation. The low inorganic mass fractions, low aerosol hygroscopicity and high externally mixed weakly CCN-active particles under low PBL height (<100 m) indicated the influence of the PBL on aerosol aging processes. In contrast, aerosol properties did not depend strongly on air mass origins or wind direction, implying that the observed aerosol and CCN are from local emissions. An error function could parameterize the relationship between CCN number and supersaturation throughout the campaign.

In calculating solar radiation, climate models make many simplifications, in part to reduce computational cost and enable climate modeling, and in part from lack of understanding of critical atmospheric information. Whether known errors or unknown errors, the community’s concern is how these could impact the modeled climate. The simplifications are well known and most have published studies evaluating them, but with individual studies it is difficult to compare. Here we collect a wide range of such simplifications in either radiative transfer modeling or atmospheric conditions and assess potential errors within a consistent framework on climate-relevant scales. We build benchmarking capability around a solar heating code (Solar-J) that doubles as a photolysis code for chemistry and can be readily adapted to consider other errors and uncertainties. The broad classes here include: use of broad wavelength bands to integrate over spectral features; scattering approximations that alter phase function and optical depths for clouds and gases; uncertainty in ice-cloud optics; treatment of fractional cloud cover including overlap; and variability of ocean surface albedo. We geographically map the errors in W m-2 using a full climate re-creation for January 2015 from a weather forecasting model. For many approximations assessed here, mean errors are ~2 W m-2 with greater latitudinal biases and are likely to affect a model’s ability to match the current climate state. Combining this work with previous studies, we make priority recommendations for fixing these simplifications based on both the magnitude of error and the ease or computational cost of the fix.

The present work is part of a greater research project aiming at creating knowledge-base for the future managerial plans dedicated to the protection of caves heritage in the Correntes Basin (3904 km 2) located in the central Brazil. Here, a GIS-based relief compartment mapping of the area is done using satellite images, geological map and cave location map as input data layers. As a result four geomorphological domains were identified as i) lowlands (282 km 2) with a base-level in silicates and carbonates, ii) the karst terrains (994 km 2) which were developed in carbonates trapped by siltstone lenses iii) the talus (1483 km 2) having colluvial and alluvial units deposited by the Urucuia escarpment retreat and iv) the highlands (1143.7 km 2) developed over the sandstone of the Urucuia Group. The intersection of landforms and geological maps resulted in two abrupt contacts, the first between lowland and karst terrains, and second between the talus and highlands which formed canyon and escarpment, respectively. Two types of the cave systems are proposed in the region as superior/vadose that collect floods from hillslopes and deep epigene fluvio-karst.

In northern Fennoscandia, semi-alluvial boulder-bed channels with coarse glacial legacy sediment are abundant, and due to widespread anthropogenic manipulation during timber-floating, unimpacted reference reaches are rare. The landscape context of these semi-alluvial rapids— with numerous mainstem lakes that buffer high flows and sediment connectivity in addition to a regional low sediment yield— contribute to low amounts of fine sediment and incompetent flows to transport boulders. To determine the morphodynamics of semi-alluvial rapids and potential self-organization of sediment with multiple high flows, a flume experiment was designed and carried out to mimic conditions in semi-alluvial rapids in northern Fennoscandia. Two slope setups (2% and 5%) were used to model a range of flows (Q1 (summer high flow), Q2, Q10 & Q50) in a 8 x 1.1 m flume with a sediment distribution analogous to field conditions; bed topography was measured using structure-from-motion photogrammetry after each flow to obtain DEMs. No classic steep coarse-bed channel bedforms (e.g., step-pools) developed. However, similarly to boulder-bed channels with low relative submergence, at Q10 and Q50 flows, sediment deposited upstream of boulders and scoured downstream. Because the Q50 flow was not able to re-work the channel by disrupting grain-interlocking from preceding lower flows, transporting boulders, or forming channel-spanning boulders, the channel-forming discharge is larger than the Q50. These results have implications for restoration of gravel spawning beds in northern Fennoscandia and highlight the importance of large grains in understanding channel morphodynamics.

This article is composed of three independent commentaries about the state of ICON principles (Goldman et al., 2021) in the AGU section Paleoclimatology and Paleoceanography (P&P), and a discussion on the opportunities and challenges of adopting them. Each commentary focuses on a different topic: (Section 2) Global collaboration, technology transfer and application, reproducibility, and data sharing and infrastructure; (Section 3) Local knowledge, global gain: improving interactions within the scientific community and with locals, indigenous communities, stakeholders, and the public; (Section 4) Field, experimental, remote sensing, and real-time data research and application. P&P projects can better include ICON principles by directly incorporating them into research proposals. A promising way to overcome the challenges of interdisciplinarity and integration is to foster networking, which will advance our research discipline through the application of ICON.

The Arctic Ocean receives a large loading of dissolved organic matter (DOM) from its catchment and shelf sediments, which can be traced across much of the basin. This signature can be used as a tracer of water mass circulation. On the shelf seas, the combination of freshwater loading from rivers and ice formation modify water mass densities and mixing considerably. These waters are the source of the halocline layer that covers much of the Arctic ocean. Our knowledge of the origins, formation and maintenance of the halocline has mostly arisen from CTD profiles and chemical tracers such as oxygen stable isotopes and inorganic nutrients, but the halocline also contains elevated levels of DOM (DOM). Here we demonstrate how this can be used as a tracer and help improve our understanding of ocean circulation. DOM fluoresce can be measured using in-situ fluorometers and mounted on autonomous platforms these can provide high spatial resolution measurements. Here we present data derived from several Ice Tethered Profilers. The data offer a unique spatial coverage of the distribution of DOM in the surface 800m below Arctic ice. Water mass analysis using temperature, salinity and DOM fluorescence, clearly distinguishs the halocline contribution of Siberian terrestrial DOM and marine DOM from the Chuckchi shelf. The findings offer a new approach to trace the distribution of Pacific waters and its export from the Arctic Ocean. Our results indicate the potential to extend the approach to fraction freshwater contributions from, sea ice melt, riverine discharge and Pacific water.

Narrow Bipolar Events (NBEs) are powerful radio emissions from thunderstorms which have been recently associated with blue optical flashes on cloud tops and attributed to extensive streamer electrical discharges named fast breakdown. Combining data obtained from a thunderstorm over South China by the space-based Atmosphere Space Interactions Monitor (ASIM), the Vaisala GLD360 global lightning network and very low frequency (VLF)/low frequency (LF) radio detectors, here we report and analyze for the first time the optical emissions of Blue LUminous Events (BLUEs) associated with negative NBEs and located at the top edge of a thundercloud. These emissions are weakly affected by scattering from cloud droplets, allowing us to estimate the source extension and optical energy involved in the process. The optical energy in the 337-nm band emitted by fast breakdown is about 10^4 J, which involves around 10^9 streamer initiation events.

We identified anomalously warm sea surface temperature (SST) events during the 40-year period 1980–2019 near a major upwelling center in the Chile-Peru Current System, using the fifth generation European Centre for Medium-Range Weather Forecasts reanalysis and focusing on time scales of 10 days to 6 months. Extreme warm SST anomalies on these time scales mostly occurred in the austral summer, December through February, with spatial scales of 1000s of km. By compositing over the 37 most extreme warm events, we estimated terms in a heat budget for the ocean surface mixed layer at the times of strongest warming preceding the events. The net surface heat flux anomaly is too small to explain the anomalous warming, even when allowing for uncertainty in mixed-layer depth. The composite mean anomaly of wind stress during the 37 anomalous warming periods has a spatial pattern similar to the resulting warm SST anomalies, analogous to previous studies in the California Current System. The weakened surface wind stress suggests reduced entrainment of cold water from below the mixed layer. Within 100-200 km of the coast, the typical upwelling-favorable wind stress curl decreases, suggesting reduced upwelling of cold water. In a 1000-km area of anomalous warming offshore, the typical downwelling-favorable wind stress curl also decreases, implying reduced downward Ekman pumping, which would allow mixed-layer shoaling and amplify the effect of the positive climatological summertime net surface heat flux.

Clouds are primary modulators of Earth's energy balance. It is thus important to understand the links connecting variabilities in cloudiness to variabilities in other state variables of the climate system, and also describe how these links would change in a changing climate. A conceptual model of global cloudiness can help elucidate these points. In this work we derive simple representations of cloudiness, that can be useful in creating a theory of global cloudiness. These representations illustrate how both spatial and temporal variability of cloudiness can be expressed in terms of basic state variables. Specifically, cloud albedo is captured by a nonlinear combination of pressure velocity and a measure of the low-level stability, and cloud longwave effect is captured by surface temperature, pressure velocity, and standard deviation of pressure velocity. We conclude with a short discussion on the usefulness of this work in the context of global warming response studies.

Rain belts in East Asia frequently pose threats to human societies and natural systems. Advances in a skillful forecast on heavy precipitation require a deeper understanding of the preconditioned environments and the hydrologic cycle. Here, we disentangle 15 dominant moisture channels along four corridors reaching the Somali Jet, South Asia, Bay of Bengal and Pacific basin for the warm-season rain belts. Among them, the Somali and South Asian channels were underappreciated in the literature. The results also highlight the importance of terrestrial moisture sources and the close relationship between the moisture pathways and rain belts' characteristics. Back-tracing the weather within a 2-week lead time reveals the pre-existing weather systems and circumglobal wave trains that govern the moisture channels. Findings from this work develop a better understanding of East Asian rain belts' water cycle and may offer insights into model evaluation and heavy rainfall prediction at a longer lead time.

Work in recent decades has demonstrated a robust relationship between tropical precipitation and the column relative humidity (CRH). This study identifies a similar relationship between CRH and the atmospheric cloud radiative effect (ACRE) calculated from satellite observations. Like precipitation, the ACRE begins to increase rapidly when CRH exceeds a critical value near 75\%. We show that the ACRE can be estimated from CRH, similar to the way that CRH has been used to estimate precipitation. Our method reproduces the annual mean spatial structure of ACRE in the tropics, and skillfully estimates the mean ACRE on monthly and daily time scales in six regions of the tropics. We propose that the exponential dependence of precipitation on CRH is a result of cloud-longwave feedbacks, which facilitate a shift from convective to stratiform conditions.

Clouds play an important role in determining Arctic warming, but remain difficult to constrain with available observations. We use two satellite-derived cloud phase metrics to investigate the vertical structure of Arctic clouds in global climate models that use the Community Atmosphere Model version 6 (CAM6) atmospheric component. We produce a set of constrained model runs by adjusting model microphysical variables to match the cloud phase metrics. Models in this small ensemble have variable representation of cloud amount and phase in the winter, while uniformly underestimating total cloud cover in the spring and overestimating it in the summer. We find a consistent correlation between winter and spring cloud cover simulated for the present-day and the longwave cloud feedback parameter.

The storage and subsequent release of water is a key function of catchments and provides a buffer against meteorological and climate extremes. While catchment storage sits at the intersection of the main hydrological processes and largely controls them, it is difficult to quantify due to catchment heterogeneity and the paucity of hydrogeological data. We adopt a multi-method approach to estimate the dynamic and extended dynamic storages using hydrometric data in 75 catchments across the south east of Australia that span across the largest mountain range in the country. The results are compared to hydrological and physical characteristics to determine the main controls of catchment storage. Each of the methods produced a wide range of storage estimates for each catchment, but estimates from each of the methods were largely ranked consistently across the study catchments. Consistent and robust relationships between catchment characteristics and estimates of storage were difficult to establish, however the results suggest that streamflow is derived from slow storage release and long flow paths while a substantial portion of storage is reserved for evapotranspiration. This study highlights some limitations with the current methodology and reinforces the need to collect data that can validate storage estimates at the catchment scale.

The causes of decadal variations in global warming are poorly understood, however it is widely understood that variations in ocean heat content are linked with variations in surface warming. To investigate the forced response of ocean heat content (OHC) to anthropogenic aerosols (AA), we use an ensemble of historical simulations, which were carried out using a range of anthropogenic aerosol forcing magnitudes in a CMIP6-era global circulation model. We find that the centennial scale linear trends in historical ocean heat content are significantly sensitive to AA forcing magnitude (-11.0$\pm$0.2 x10$^{19}$ (J m$^{-1}$ century$^{-1}$)/(W m$^{-2}$), R$^2$=0.99), but interannual to multi-decadal variability in global ocean heat content appear largely independent of AA forcing magnitude. Comparison with observations find consistencies in different depth ranges and at different time scales with all but the strongest aerosol forcing magnitude, at least partly due to limited observational accuracy. We find broad negative sensitivity of ocean heat content to increased aerosol forcing magnitude across much of the tropics and sub-tropics. The polar regions and North Atlantic show the strongest heat content trends, and also show the strongest dependence on aerosol forcing magnitude. However, the ocean heat content response to increasing aerosol forcing magnitude in the North Atlantic and Southern Ocean is either dominated by internal variability, or strongly state dependent, showing different behaviour in different time periods. Our results suggest the response to aerosols in these regions is a complex combination of influences from ocean transport, atmospheric forcings, and sea ice responses.

Blending is a promising strategy during the partial replacement of plant with animal proteins. This, however, may lead to alteration in the technofunctional properties of the resultant blends. In this study, soy, rice and pea protein concentrates (SPC, RPC and PPC, respectively) were blended with milk protein concentrate (MPC) at different ratios: 25:75, 50:50 and 25:75 and the technofunctional properties relevant to their emulsification behaviour, e.g., emulsion stability, viscosity and water and oil binding capacity, were investigated. At equivalent concentrations, the plant protein concentrates had higher apparent viscosities compared to MPC and the blends. RPC-MPC, at all ratios, had a lower oil binding capacity when compared with the SPC-MPC and PPC-MPC blends. Plant protein-MPC blends showed higher emulsion stability compared to the individual plant protein concentrates. Blending MPC with plant protein concentrates resulted in promising improvements in emulsification behaviour of relevance to different composite protein ingredient applications.

Clouds cover on average nearly 70% of Earth’s surface and regulate the global albedo. The magnitude of the shortwave reflection by clouds depends on their location, optical properties, and three-dimensional (3D) structure. Due to computational limitations, Earth system models are unable to perform 3D radiative transfer calculations. Instead they make assumptions, including the independent column approximation (ICA), that neglect effects of 3D cloud morphology on albedo. We show how the resulting radiative flux bias (ICA-3D) depends on cloud morphology and solar zenith angle. Using large-eddy simulations to produce 3D cloud fields, a Monte Carlo code for 3D radiative transfer, and observations of cloud climatology, we estimate the effect of this flux bias on global climate. The flux bias is largest at small zenith angles and for deeper clouds, while the negative albedo bias is most prominent for large zenith angles. In the tropics, the radiative flux bias from neglecting 3D radiative transfer is estimated to be 4.0 +/- 2.4 Wm-2 in the mean and locally as large as 9 Wm-2.

The continuous estimation of changes in seismic velocity and seismic scattering property by passive interferometry using seismic ambient noise is a promising tool for monitoring volcanoes. To improve the usefulness of this method, it is necessary not only to detect subsurface structural changes but also to quantitatively compare the estimated changes in seismic wave velocity and seismic wave scattering property with other observations such as ground deformation. We applied passive interferometry to continuous seismic records from Suwanosejima volcano, Japan, recorded between April 2017 and December 2021. We detected repeated significant waveform decorrelations in seismic ambient noise cross-correlation functions, indicating seismic scattering property changes in the shallow areas of the volcano. These decorrelations were observed from 2 week to a few days before the increase in the number of explosions, suggesting that seismic scattering properties changed significantly during that period. We found that the timing of the decorrelation in seismic ambient noise cross-correlation functions and tilt changes related to magma accumulation and injection beneath Suwanosejima were well synchronized. The high correlation between the amounts of decorrelation and tilt change during the magma accumulation period suggests that a large volume of accumulated magma caused great changes in the scattering property. These results provide a significant first step toward a quantitative comparison of the amount of changes in the scattering property with the amount of magma accumulation beneath volcanoes.