Arctic sea ice cover has been steeply declining since the onset of satellite observations in the late 1970s. However, the available annually resolved sea ice data prior to this time are limited. Here, we evaluated the suitability of annual trace element (Mg/Ca) ratios and growth increments from the long-lived annual increment-forming benthic coralline red alga, Clathromorphum compactum, as high-resolution sea ice cover c. It has previously been shown that growth and Mg/Ca of C. compactum are strongly light controlled and therefore greatly limited during polar night and underneath sea ice cover. We compare algal data from 11 sites collected throughout the Canadian Arctic, Greenland and Svalbard, with satellite sea ice data. Our results suggested that algal growth anomalies most often produced better correlations to sea ice concentration than Mg/Ca alone or when averaging growth and Mg/Ca anomalies. High Arctic regions with persistently higher sea ice concentrations and shorter ice-free seasons showed strongest correlations between algal growth anomalies and satellite sea ice concentration over the study period (1979-2015). At sites where ice breakup took place prior to the return of sufficient solar irradiance, algal growth was most strongly tied to a combination of solar irradiance and other factors such as temperature, suspended sediments, phytoplankton blooms and cloud cover. These data are the only annually resolved in situ marine proxy data known to date and are of utmost important to gain a better understanding of the sea ice system and to project future sea ice conditions.

Despite the importance of turbidity currents in environmental and resource geology, their flow conditions and mechanism are not well understood. To resolve this issue, a new method for the inverse analysis of turbidity current using deep learning neural network (DNN) was proposed. This research aims at verifying and calibrating this method using artificial and flume experiment datasets. The forward model based on the shallow water equation was employed in this study to produce artificial datasets of turbidite deposits. DNN was applied to two hundred artificial datasets and two sets of experiment data. As a result of inversion by DNN, spatial distributions of grain size and thickness of experimental turbidites were reconstructed accurately. With regard to hydraulic conditions, the flow heights were reasonably estimated, and sediment concentrations reconstructed were reasonable except for regions where the values measured in experiments were extremely low. Flow duration also showed reasonable reconstructed values. In contrast to the other values, there was a large discrepancy between the measured and reconstructed values of flow velocity. The reason for this discrepancy in velocity may be attributed to inaccuracy in closure functions employed in the forward model. Future application to actual data of natural scale turbidite is anticipated.

The sustainable management of groundwater demands a faithful characterization of the subsurface. This, in turn, requires information which is generally not readily available. To bridge the gap between data need and availability, numerical models are often used to synthesize plausible scenarios not only from direct information but also additional, indirect data. Unfortunately, the resulting system characterizations will rarely be unique. This poses a challenge for practical parameter inference: Computational limitations often force modelers to resort to methods based on questionable assumptions of Gaussianity, which do not reproduce important facets of ambiguity such as Pareto fronts or multi-modality. In search of a remedy, an alternative could be found in Stein Variational Gradient Descent, a recent development in the field of statistics. This ensemble-based method iteratively transforms a set of arbitrary particles into samples of a potentially non-Gaussian posterior, provided the latter is sufficiently smooth. A prerequisite for this method is knowledge of the Jacobian, which is usually exceptionally expensive to evaluate. To address this issue, we propose an ensemble-based, localized approximation of the Jacobian. We demonstrate the performance of the resulting algorithm in two cases: a simple, bimodal synthetic scenario, and a complex numerical model based on a real-world, pre-alpine catchment. Promising results in both cases - even when the ensemble size is smaller than the number of parameters - suggest that Stein Variational Gradient Descent can be a valuable addition to hydrogeological parameter inference.

In this study, we investigate the oceanic and atmospheric processes that have contributed to the Rapid Intensification (RI) and Rapid Weakening (RW) of Cyclone Ockhi using the HYbrid Coordinate Ocean Model (HYCOM) simulations and Global Forecast System (GFS) outputs. The environmental conditions prevailed before RI showed the presence of thick warm and fresh waters, ample supply of mid-tropospheric relative humidity, and moderate wind shear. The intrusion of dry air, strong vertical wind shear, and unfavourable oceanic conditions annihilated the storm intensity during the RW stage. Compared to the ocean temperature, the vertical structure of salinity showed remarkable differences between the RI and RW locations resulting in contrasting upper-ocean stratification. The dynamic temperature (T$_{dy}$) under the TC core evolved under the influence of upper-ocean stratification showed a large drop at RW compared to RI. T$_{dy}$ provided a better representation of the ocean’s negative feedback on the rapid intensity changes of TC Ockhi compared to TCHP, especially for the region like RI, which was primarily influenced by the salinity stratification. Hence, this study demonstrates the importance of multi-parameter metric like T$_{dy}$ in the assessment of oceanic feedback to TC and its intensity changes.

10 Techniques for fast large-volume sampling of total gaseous mercury (TGM) in the air 11 and extracting the TGM with 5 mL acid solution were developed for stable mercury 12 isotope ratio measurements. A Big gold coated sand Trap (BAuT), a 45 mm i.d. × 300 13 mm length quartz tube containing 131 times more gold coated silica than a conventional 14 gold trap has, was used for the collection of a large amount of TGM from the air. The 15 collected TGM was then extracted by 5 mL reversed aqua resia in a 2L Tedler bag, and 16 the extract was analyzed by a cold-vapor generator coupled with a multi collector 17 inductively coupled plasma mass spectrometer for the isotopic compositions. The 18 sampling tests of BAuT showed 99.9% or higher collection efficiency during the 19 sampling time of 1-24 h under the flow rate of 20-100 L min-1. Recovery tests of the 20 bag extraction using 100 ng of NIST SRM 8610 exhibited nearly 100% of recovery 21 yields and agreement of the measured five stable mercury isotope ratios with the 22 reference values within 2  of uncertainty when using the trapping solution of 40% 23 reversed aqua resia with the extraction time of a day. The overall methodology tested in 24 the pilot field and laboratory studies demonstrated the successful analysis, promising 25 highly precise stable mercury isotopic data with the time resolution less than a day. Part 26 of the procedure can be automated, ideal for unmanned sampling at a remote site.

Studies reconstructing surface paleoproductivity and benthic conditions allow us to measure the effectiveness of the biological pump, an important mechanism in the global climate system. In order to assess surface productivity changes and their effect on the seafloor, we studied the core SAT-048A, recovered from the continental slope of the southernmost Brazilian continental margin, in the western South Atlantic. We assessed the sea surface productivity, the organic matter flux to the seafloor and the dissolution effects, based on micropaleontological (benthic and planktonic foraminifers, ostracods), geochemical (benthic and planktonic δ13C isotopes) and sedimentological data (carbonate and bulk sand content). Superimposed on the climate-induced changes related to the last glacial-interglacial transition, the reconstruction indicates paleoproductivity changes synchronized with the precessional cycle. From the reconstructed data, it was possible to identify high (low) surface productivity, high (low) organic matter flux to the seafloor, and high (low) dissolution rates of planktonic Foraminifera tests during the glacial (postglacial). Furthermore, within the glacial, enhanced productivity was associated with higher insolation values, explained by increased NE summer winds that promoted meandering and upwelling of the nutrient-rich South Atlantic Central Water. Changes in the Atlantic Meridional Overturning Circulation and the reorganization of bottom water masses could also have changed the CO3 2- saturation levels and have influenced the carbonate preservation. However, changes in the Uvigerina spp. δ13C values are very likely linked to the organic matter flux and not to the sea bottom dissolved inorganic matter δ13C values.

In the publication Troshichev et al. (2006) on the Polar Cap (PC) indices, PCN and PCS, an error was made by using components of the Interplanetary Magnetic Field (IMF) in their Geocentric Solar Ecliptic (GSE) representation instead of the prescribed Geocentric Solar Magnetospheric (GSM) representation for calculations of index scaling parameters. The mistake has caused a trail of incorrect relations and wrong conclusions extending since 2006 up to now (2020) which should be discontinued, for instance, by issuing a corrigendum note from the authors. The present comment explains the error and discusses in an extended example its consequences for one of the publications that has referenced to the invalid scaling parameter set.

In their study, Dong and Ochsner (2018) used an extensive dataset of 18 cosmic-ray neutron rover surveys to assess the influence of precipitation and soil texture on mesoscale soil moisture patterns. Based on their analysis, they concluded that soil texture, represented by sand content, often exerts a stronger influence on mesoscale soil moisture variability than precipitation, represented by the antecedent precipitation index. However, we consider that Dong and Ochsner (2018) made a mistake in their calculation of volumetric soil moisture, such that their analysis on the influence of soil texture on soil moisture is not valid. This result does however not bring into question the paper’s conclusion on the influence of soil texture on mesoscale soil moisture patterns.

This study examines the characteristics of several model parameter perturbation methodologies for ensemble simulations of cloud microphysical processes in convection. A simplified 1D model is used to focus the results on cloud microphysics without the complication of feedbacks to the dynamics and environment. Several parameter perturbation methods are tested, including non-stochastic and stochastic with various distributions and parameter covariance. We find that an ensemble comprised of different time-invariant parameters (non-stochastic) exhibits little bias, but insufficient spread. In addition, its behavior does not respect the time evolution of convection through its various phases. Stochastic parameter (SP) methods in which no inter-parameter covariance is applied produce greater spread, but significant bias. The bias is particularly large for lognormal parameter perturbation distributions. The ensemble spread is retained and the bias reduced when time-varying parameter covariance is applied. In this case, the SP scheme is able to adapt to the time and state-dependent covariance structures and produce ensemble characteristics that are consistent with the specific microphysical processes operating at any given time. The results suggest that SP schemes would benefit from inclusion of parameter covariances, and specifically those that vary with the state of the system. It also suggests that a Normal or LogNormal SP scheme with no covariance may produce a significantly biased ensemble. Finally, the results indicate that high temporal and spatial resolution observations may be needed to characterize the variability in parameter values and covariance.

Floating photovoltaic solar energy (FPV) are solar photovoltaic systems that float on bodies of water. They are a rapidly expanding renewable energy source emerging as an alternative to land-intensive ground-mounted solar arrays. The applications of this technology are commonly explored through technical potential assessments; a vital step in the development of renewable energy resources that allow for the identification of feasible installation sites and provide an estimation of costs, power generation, and capacity (Lee and Roberts 2018). These assessments are carried out to aid planners, policymakers, and other decision-makers in predicting and achieving goals related to the development of renewable energy; however, some considerations may be overlooked. Assessing the technical potential of solar energy without a standardized methodological framework for site selection may lead to an inconsistent range of generation outcomes, adding to the confusion and lack of confidence that has been a significant barrier to the growth of renewable energy in recent years (Seetharaman 2019) This study systematically reviewed criteria in the published literature emphasizing assessment of FPV technical potential and related siting studies, especially those using geographic technologies. The systematic review was performed in alignment with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Preliminary findings of this systematic review suggest that FPV site selection criteria can be categorized into economic, social, environmental, and technical considerations. We aim to elucidate which criteria within each classification are important to include in an FPV siting study based on the current literature. Results from this analysis will inform the standardization of a site-selection framework used in future technical potential studies, which may, in turn, improve the accuracy of generation estimates and offer a meaningful and realistic idea of how FPV installations could transform the direction of renewable energy science and development.

Hydrologic and water quality models are often used to understand and simulate non-point source nutrient inputs to receiving waterbodies afflicted by eutrophication. The most widely used hydrologic-water quality model for estimating non-point source nutrient loads from agricultural uplands is the Soil and Water Assessment Tool (SWAT). SWAT uses the QUAL-2E 1-dimensional steady-state model to simulate in-stream processes that govern the transport of nutrients through channels and rivers. However, the instream-solute transport routine within SWAT is limited in predicting phosphorus cycling and algal dynamics. In this study, we improve the in-stream module of SWAT+, a restructured version of SWAT. We apply the modified SWAT+ to the Western Lake Erie Basin to examine how improved representation of the in-stream module influences nutrient dynamics from the edge-of-field through streams and to the watershed outlet. Our source code modifications focus on improving the representation of phosphorus exchange between the stream bed and the water column. This phosphorus exchange is governed by the equilibrium phosphorus concentration (EPC), which determines whether the stream bed is a phosphorus source or sink, and a phosphorus transformation coefficient which determines the rate of P exchange. These improvements to the in-stream routine within SWAT+ will aid decision-makers in understanding the time lags and management levers needed to achieve water quality targets for large basins.

Abstract The repetitive narrative that, “Tsunami waves and receded coastal water initiated by an earthquake are closely related,” is analyzed through the sequential events that followed the earthquake; a mechanism based on the interaction of receded water with magma is suggested to explain the amplification of Tsunami wave deep beneath the ocean floor (Fig.1), where earthquake occurred under the seabed’s or in coastline; the mechanism explained how the water is amplified into steam in the magma chamber, as its volume increased 1,700 times, the transformed water encompass the tremendous force that uplifted the ocean water endowed it with such destructive force; the mechanism explained characteristics related to Tsunami wave, including relation with earthquake and volcano, receding costal water, the foams, inundation, runup, the nature of the great force of Tsunami, ideas to calculate the magnitude of Tsunami force and energy, volume of receded water, volume of tsunami wave, the repetition of its wave; these and related issues are stated; the idea is derived based on the continual flow of lava from earth’s interior and the existence of magma reservoir bellow earth’s surface in places like Yellowstone in USA and hotspot beneath Hawaii, such magma chamber when existed under seabed, if opened by crack during earthquake, can easily lead to an interaction between receded water and the magma, resulted in the suggested mechanism, all is based on logical analyses and deep thinking to attained the Tsunami Mechanism in response to 2004 and 2011 human tragedies; thus understanding this mechanism will help laying measures to counter the phenomenon, which will reflect positively in saving lives and mitigate its destructive force and reduce consequences of its impact on local societies and above all to understand its true mechanism.

Central peaks of lunar complex craters of Copernican period provide best examples to study morphologies of impact melts and exposed subsurface as they are better preserved and less affected by the space weathering. Crater Tycho, present towards SW, nearside of the Moon is one such example of young and fresh complex crater. Present study is high-resolution mineralogical investigation coupled with morphological study of central peaks and floor of crater Tycho and other contemporary craters to understand the nature of occurrence and distribution of compositionally distinct lithologies identified near their central peaks that differ in colour and specific appearance. A detailed high-resolution analysis suggests that the clastic exposures associated with the melts have a mafic composition that have been observed at similar other contemporary craters. They represent the fragmental polymict breccia clasts and their stratigraphic relation with the melts alongwith with their mineralogy suggests them to be representative of subsurface anorthositic gabbro/noritic body. Their occurrence and association with structural features, such as breccias dikes and cooling cracks suggest their formation at different stages of cratering and associated crustal modification. The formation mechanism of the polymict breccia clasts causing lithological variability has been discussed. We also report here the occurrence of rejuvenated dykes peculiar to Tycho setting that are distinct from the fractures in the immediate viscinity. Their unique nature suggests different emplacement mechanism associated with dynamic cratering process till not reported at any young complex crater on the Moon.

Accurate measurements of P/S ratios at local-regional scale are often challenged by near-distance failure and/or sparse monitoring. During June 2014 - Aug. 2016 (iMUSH project), the XD array was deployed around the Mount St. Helens (MSH, hear and after) within ~150 km of the summit. The array contains ~80 three-component broadband stations, forming a nearly uniform monitoring system that recorded 23 active shots and 407 of M>1 earthquake within the 2-year period. The determined local magnitudes for the shots range from 0.9 to 2.3. Most earthquakes are deep (>10 km) and the shots are 10m below the surface. Due to the complexity of near surface structure, waveforms of the shots have both strong P and S energy on the transverse components, leaving them identical to earthquakes. This study takes advantage of this integrate dataset to systematically evaluates potential contributing factors to the P/S ratio measurements, including: source type (i.e., explosive vs. shear), distance, depth, and station location (i.e., site effect, coverage). We also compared between different frequency ranges, window choices, methods and component choices (i.e., RTZ vs. LQT) that differentiate the shots from the earthquakes. We observed no clear dependence for P-to-S ratio over depth, azimuth nor magnitude, while other parameters could be optimized to isolate contributions from the source. For example, the P-to-S ratios increase with frequency from 4Hz to 18 Hz and shots show much larger increasements than the earthquakes. We suggest that the near-source challenges could be relieved by: 1) use narrow windows to capture early phase and avoid overlap between S-coda and surface wave, 2) use higher frequency range to enhance body wave signal-to-noise ratio and allow for enough period within narrow phase windows, 3) rotate from the RTZ system to LQT system to maximize P wave energy and/or 4) include the transverse (T) component in P-phase energy calculations. With these optimizations, our averaged ratios are consistent throughout all distances (6-160 km) and clearly separate the shots from the earthquakes. In addition, regardless of the source type, the P-to-S ratios also vary with station location, which could be attributable to site effect and local structures.

The middle thermospherefrom ~150 to 250 km is characterized by rapid increase in temperature with altitude and rapid ionization. The entire thermosphere is believed to be home to atmospheric waves that propagate through it, originating both in the atmospheric layers below and in the thermosphere itself. Within the middle thermosphere, direct observations of such waves are extremely sparse. The GOLD far-UV imaging spectrometer is able to observe the middle thermosphere from geostationary orbit. During October 2018 a special observational campaign was performed, designed to identify atmospheric waves. Signatures in the 135.6 nm O airglow were seen that move northwards with time, away from the Southern polar region. These are consistent with a large-scale atmospheric gravity wave. These results are the first time 135.6 nm airglow has been used to track such a wave and highlight the ability of GOLD to observe such waves, even when at a modest amplitude, and track their motion.

An alternative approach to assess the South America intraseasonal variability is presented. In this study, we use a normal-mode decomposition method to decompose the South American 30-90-day Low-Frequency Intraseasonal (LFI) and 10-30-day High-Frequency Intraseasonal (HFI) variability systematically into rotational (ROT) and inertio-gravity (IGW) components in the reanalysis data. The seasonal cycle of the LFI and HFI convective and dynamical structure is well-described by the first leading pattern (EOF1). The LFI EOF1 spatial structure during the rainy season is the dipole-like between the South Atlantic Convergence Zone (SACZ) and southeastern South America (SESA), influenced by the large-scale Madden-Julian Oscillation (MJO). During the dry season, alternating periods of enhanced and suppressed convection over South America is primarily controlled by extratropical wave disturbances. The HFI spatial pattern also resembles the SESA–SACZ structure, in response to the Rossby wave trains. Results based on normal-mode decomposition of reanalysis data and the LFI and HFI indices show that the tropospheric circulation and SESA–SACZ convective structure observed over South America are dominated by ROT modes (Rossby). A considerable portion of the LFI variability is also associated with the inertio-gravity (IGW) modes (Kelvin mode), prevailing mainly during the wet season. The proposed decomposition methodology provides insights into the dynamic of the South America intraseasonal variability, giving a powerful tool for diagnosing circulation model issues in order to improve the prediction of precipitation.

The structure of electric fields in the atmosphere still escapes from the detailed in situ measurements. Few balloon flights although providing us with overall knowledge of possible structures and strengths of the atmospheric electric fields, cannot reveal the dynamics of the intracloud electric field responsible for intense runaway electron fluxes and atmospheric discharges. To get insight into the charge structure of the thundercloud we use new key evidence – the fluxes of particles from the thundercloud registered on the earth’s surface, the so-called Thunderstorm Ground Enhancements – TGEs. TGEs originate from electron acceleration and multiplication processes in the strong electric fields in the atmosphere, and the intensity and energy spectra of electrons and gamma rays as observed at the Earth’s surface are directly governed by the charge structure of the cloud.

We use a 3-D chemical transport model and satellite observations to investigate Arctic ozone depletion in winter/spring 2019/20 and compare with earlier years. Persistently low temperatures caused extensive chlorine activation through to March. March-mean polar-cap-mean modelled chemical column ozone loss reached 78 DU (local maximum loss of ~108 DU in the vortex), similar to that in 2011. However, weak dynamical replenishment of only 59 DU from December to March was key to producing very low (<220 DU) column ozone values. The only other winter to exhibit such weak transport in the past 20 years was 2010/11, so this process is fundamental to causing such low ozone values. A model simulation with peak observed stratospheric total chlorine and bromine loading (from the mid-1990s) shows that gradual recovery of the ozone layer over the past two decades ameliorated the polar cap ozone depletion in March 2020 by ~20 DU.