In 2003, the New York State Department of Environmental Conservation began designating Potential Environmental Justice Areas (PEJA) for the purpose of providing additional public participation opportunities to disadvantaged populations during permitting deliberations. We developed NYenviroScreen to help stakeholders understand, review, and provide input for how future PEJA designation might be updated and improved, including for identifying disadvantaged communities under the newly enacted Climate Leadership and Community Protection Act (CLCPA). We present and compare three potential update methods and provide an interactive web application for investigating model components and composition. The three methods are: (i) three factor clustering using the Jenks natural breaks algorithm, (ii) a cumulative impact model adapted from CalEPA’s CalEnviroScreen, and (iii) a hybrid approach that utilizes both methods and incorporates Native American land areas. NYenviroScreen brings together federal and state data sources related to population health, sociodemographics, environmental risk factors, and potential pollution exposures for 15,463 census block groups. We find that a hybrid approach provides the most robust coverage for both rural and urban areas of New York State. By innovating new approaches to such designations and making them publicly accessible, we contribute to the pursuit of environmental justice in New York by generating actionable science.

An evaluation of three climate models is conducted using in situ airborne observations from the Southern Ocean Clouds, Radiation, Aerosol Transport Experimental Study (SOCRATES) campaign. The evaluation targets cloud phases, microphysical properties, thermodynamic conditions, and aerosol indirect effects at -40°C – 0°C. For cloud phase frequency distribution, the Community Atmosphere Model version 6 (CAM6) shows the most similar result to the observations, which allows more liquid-containing clouds below -10°C compared with its predecessor – CAM5. The Energy Exascale Earth System Model (E3SM) underestimates (overestimates) ice phase frequencies below (above) -20°C. Compared with 580-second averaged observations (i.e., 100 km horizontal scale), CAM6 and E3SM overestimate (underestimate) liquid (ice) water content (i.e., LWC and IWC), leading to lower a glaciation ratio when ice and liquid coexist. Thermodynamic conditions, specifically relative humidity (RH), is likely a key factor contributing to model cloud occurrence and cloud phase biases. Simulated in-cloud RH shows higher minimum values than observations, possibly restricting ice growth during sedimentation. As number concentrations of larger and smaller aerosols (> 500 nm and > 100 nm) increase, observations show increases in glaciation ratio, cloud fraction, LWC and liquid number concentration (Nliq) at -18°C to 0°C, and IWC and ice number concentration (Nice) at -35°C to 0°C. CAM6 and E3SM show slight increases of LWC and Nliq, and E3SM shows small increases of Nice. These results indicate that models underestimate aerosol indirect effects on ice and mixed phase clouds over the Southern Ocean.

In order to assess the sedimentological and stratigraphic history of the Melas Chasma rift basin, Mars, and investigate the possibility of past bodies of water, we have mapped Hesperian stacked sedimentary deposits containing what appear to be 102 m scale topsets, clinoforms, toesets and olistoliths located on the immediate hangingwall of a normal fault, and correlated these with folded and slumped units on the basin floor. The vertical extent of clinoforms suggest deposition in bodies of water that were tens to hundreds of metres deep associated with gravity-driven mass-movement of sediment to the basin floor. We correlated the basin margin deposits with basin-floor deposits by mapping unconformities, which define four depositional sequences. Using the principles of sequence stratigraphy in rifts, developed for terrestrial analogues in the Gulf of Corinth, Greece, we infer the history of the Melas Chasma deposits. Results suggest that water-high-stand delta deposits became stacked across unconformities in a basin undergoing active hangingwall subsidence. Assuming slip-rates on the basin-bounding normal fault similar to that found on other terrestrial and Martian faults, we infer timescales of ~1.25 to 15 million years for the sedimentation and water body. We discuss our findings in terms of a possible connection to the putative paleo-ocean on the Martian northern hemisphere.

The spatial patterns of earthquake ground motion amplitudes are commonly represented using a double couple model that corresponds to shear slip on a planar fault. While this framework has proven successful in explaining low-frequency seismic recordings, at higher frequencies the wavefield becomes more azimuthally isotropic for reasons that are not yet well understood. Here we use a dense array of nodal seismometers in Oklahoma to study the radiation patterns of earthquakes in the near-source region where wavefield scattering effects are limited. At these close distances, the radiation pattern is predominantly double couple at low frequencies (<15Hz). At higher frequencies, the recorded wavefield contains significant isotropic and residual components that cannot be explained as path or site effects, implying complexity in the rupture process or local fault zone structure. These findings demonstrate that earthquake source complexity can drive variability in the ground motions that control seismic hazard.

Environmental observatory networks (EONs) provide information to better understand, model and forecast the spatial and temporal dynamics of Earth’s biophysical process. Consequently, representativeness analyses of EONs are important to provide insights for improving EONs’ management, design, and interpretation of their value-added products (e.g., datasets, model predictions). We assessed the representativeness of registered FLUXNET sites (n=41, revised on September 2018) across Latin America (LA), a region of great importance for the global carbon and water cycles, which represents nearly 13% of the world’s land surface area. Representativeness analyses were performed using a 0.05o spatial grid for multiple environmental variables, gross primary productivity (GPP) and evapotranspiration (ET) across LA. Our results showed a potential spatial representativeness of 34% of the surface area for climate properties, 36% for terrain parameters, 34% for soil resources, and 45% when all aforementioned environmental variables were summarized into a principal component analysis. Furthermore, there was a 48% potential representativeness for GPP and 34% for ET. Unfortunately, data from these 41 sites is not all readily available for the scientific community, limiting synthesis studies and model benchmarking/parametrization. We discussed the need to enhance interoperability, promote the participation of active/inactive sites to share information with local, regional and international networks, and promote monitoring efforts across this region of the world to increase the accuracy of regional-to-global data-driven products.

Understanding and predicting bedload transport is an important element of watershed management. Yet, predictions of bedload remain uncertain up to several order(s) of magnitude. In this contribution, we use a five-year continuous time-series of streamflow and bedload transport monitoring in a 13.4 km2 snow-dominated Alpine watershed in the Western Swiss Alps to investigate the hydrological drivers of bedload transport. Following a calibration of the bedload sensors, and a quantification of the hydraulic forcing of streamflow upon bedload, a hydrological analysis is performed to identify daily flow hydrographs influenced by different hydrological drivers: rainfall, snow-melt, and mixed rain and snow-melt events. We then quantify their respective contribution to bedload transport. Results emphasize the importance of mixed rainfall and snow-melt events, for both annual bedload volumes (77% in average) and peaks in bedload transport rate. Results further show that a substantial amount of bedload transport may occur during late summer and autumn storms, once the snow-melt contribution and baseflow have significantly decreased (9% of the annual volume in average). Although rainfall-driven changes in flow hydrograph are responsible for a large majority of the annual bedload volumes (86% in average), the identified melt-only events also represents a non-negligible contribution (14 % in average). Through a better understanding of the bedload magnitude-frequency under different hydrological conditions, the results of this study may help to improve current predictions of bedload transport, and we further discuss how bedload could evolve under a changing climate through its effects on Alpine watershed hydrology.

All current understanding (theoretical and observational) suggests that the development of the solar wind and CMEs takes place within 10 Rs, particularly below 4 Rs. This seemingly narrow spatial region encompasses the transition of coronal plasma processes through the entire range of physical regimes from fluid to kinetic, and from primarily closed magnetic field structures to primarily open. For these reasons, we refer to it as the Critical Coronal Transition Region (CCTR). Its comprehensive exploration will answer two of the most central Heliophysics questions with repercussions across NASA and society. Here, we outline a path to answer these questions in the next 30 years.

In recent years, there has been a significant sea ice retreat in the Pacific sector of the Arctic. One possible cause is the increase in ocean heat flux amplified by the ice-albedo feedback. This paper looks at vertical ocean heat transport from waters of Pacific origin and solar heat into the mixed layer and their impact on the sea ice mass balance in the Community Earth System Model - Large Ensemble (CESM-LE). To this end, we focus on two specific periods with observational hydrographic data from the Arctic Ice Dynamics Joint Experiment (1975-76) and Ice-Tethered Profiler (2004-2018). A comparison between simulated and observed salinity and potential temperature profiles highlights two key model biases in all ensemble members: an absence of Pacific Waters in the water column and a deepening of the winter mixed layer in opposition to observations that show a reduction in depth of the mixed layer and a stronger increase in stratification. Results from a one-dimensional vertical heat budget show that remnant solar heat trapped beneath the halocline is mostly ventilated to the surface by mixing before the following melt season, while vertical advection associated with Ekman pumping, even in early fall when the winds are strong and the pack-ice weak, only has a small effect on the vertical heat transport. Furthermore, we estimate from the 1D heat budget a reduction of 1.4 m winter ice growth over three years (the residence time of ice in the Beaufort Gyre) associated with the missing Pacific Waters.

Past studies reported a drastic growth in the wildland-urban interfaces (WUI), the locations where man-made structures meet or overlap wildland vegetation. There is a perception that damages due to wildfires are mainly located at the WUI. However, there is no clear evidence that wildfire intensity and frequency are highest in these regions. In this work, we have reported the actual occurrences of wildfires with respect to WUI and how much of the WUI are on complex topography in California (CA), the state with the highest burned area and risk of wildfires. We calculated the overlap of the burned area from previous wildfire events in California in the last ten years with the WUI perimeters. Two currently existing WUI definitions are used for this purpose. Furthermore, we also calculated the number of fire ignition points that lie within the WUI perimeters. We found that a very small percentage of wildfire ignitions actually occurred in the WUI areas. Moreover, the overlap between the wildfire burned area and WUI areas was also found to be small. To find out if the wildfires burned in the vicinity of WUI areas, we created buffers around both the WUI areas and the wildfire perimeters separately and computed the impact of buffer distance on the overlap. This behavior has been connected to the importance of firebrand ignition from spot fires in the WUI. Moreover, a majority of WUI areas in CA was found to be situated on complex topography. Therefore, we conclude that in CA, wildfires are not limited to WUI regions only, but their main fire fronts burn farther away from the WUI and are mostly located on complex topography, where controlling large wildfires is more difficult and fire behavior is more complex. Results from this study will give direction for remapping the existing WUI definitions, will be helpful for wildfire management and will benefit policymakers and land managers at the state and local level to focus on the factors that determine the high-risk prone areas for future wildfires.

Media propagation noises are amongst the main error sources of radiometric observables for deep space missions, with fluctuations of the tropospheric excess path length representing a relevant contributor to the Doppler noise budget. Microwave radiometers currently represent the most accurate instruments for the estimation of the tropospheric delay and delay rate along a slant direction. A prototype of a tropospheric delay calibration system (TDCS), using a 14 channel Ka/V band microwave radiometer, has been developed under a European Space Agency contract and installed at the deep space ground station in Malargüe, Argentina, in February 2019. After its commissioning, the TDCS has been involved in an extensive testbed campaign by recording a total of 44 tracking passes of the Gaia spacecraft, which were used to perform an orbit determination analysis. This work presents the first statistical characterization of the end-to-end performance of the TDCS prototype in an operational scenario. The results show that using TDCS-based calibrations instead of the standard GNSS-based calibrations leads to a significant reduction of the residual Doppler noise and instability.

We present a 500-year history of naturally felled driftwood incursion to northern Svalbard, directly reflecting regional sea ice conditions and Arctic Ocean circulation. Provenance and age determinations by dendrochronology and wood anatomy provide insights into Arctic Ocean currents and climatic conditions at a fine spatial resolution, as crossdating with reference chronologies from the circum-Arctic boreal forests enables determination of the watershed the driftwood originated from. Sample crossdating may result in a wide range of matches across the pan-boreal region, which may be biased towards regions covered by the reference chronologies. Our study considers alternate approaches to selecting probable origin sites, by weighting scores via reference chronology span and visualising results through spatiotemporal density plots, as opposed to more basic ranking systems. As our samples come from naturally felled trees (as opposed to logged, or both), the relative proportions of different provenances are used to infer past ocean current dominance. Our record indicates centennial-scale shifts in source regions for driftwood incursion to Svalbard, aligning with Late Holocene high variability and high frequency shifts in the Transpolar Drift and Beaufort Gyre strengths and associated fluctuating climate conditions. Driftwood occurrence and provenance also tracks the northward seasonal ice formation shift and migration of seasonal sea ice to the peripheral Arctic seas in the past century. A distinct decrease in driftwood incursion during the last 30 years matches the observed decline in pan-Arctic sea ice extent in recent decades. Our new approach successfully employs driftwood as a robust proxy for Arctic Ocean surface current and sea ice dynamics.

A ~ 50 km resolution atmospheric general circulation model (GCM) is used to investigate the impact of radiative interactions on spatial organization of convection, the model’s mean state, and extreme precipitation events in the presence of realistic boundary conditions. Mechanism-denial experiments are performed in which synoptic-scale feedbacks between radiation and dynamics are suppressed by overwriting the model-generated atmospheric radiative cooling rates with its monthly-varying climatological values. When synoptic-scale radiative interactions are disabled, the annual mean circulation and precipitation remain almost unchanged, however tropical convection becomes less aggregated, with an increase in cloud fraction and relative humidity in the free troposphere but a decrease in both variables in the boundary layer. Changes in cloud fraction and relative humidity in the boundary layer exhibit more sensitivity to the presence of radiative interactions than variations in the degree of aggregation. The less aggregated state is associated with a decrease in the frequency of extreme precipitation events, coincident with a decrease in the dynamical contribution to the magnitude of extreme precipitation. At regional scales, the spatial contrast in radiative cooling between dry and moist regions diminishes when radiative interactions are suppressed, reducing the upgradient transport of energy, degree of aggregation and frequency of extreme precipitation events. However, the mean width of the tropical rain belt remains almost unaffected when radiative interactions are disabled. These results offer insights into how radiation-circulation coupling affects the spatial organization of convection, distributions of clouds and humidity, and weather extremes.

Some spherical harmonic expressions (SHEs) of gravitational and geomagnetic field elements will become infinite when computation point approaches polar regions, as the sine function of the geocentric co-latitude contained in the denominator tends to be zero. Currently, this singularity problem has been solved for gravitational field case, however, it remains unsolved for geomagnetic vectors (GVs) and geomagnetic gradient tensors (GGTs). The reason is that the latter use Schmidt semi-normalized associated Legendre function (SNALF), which is different from fully-normalized associated Legendre function (FNALF) used in the former. To overcome this singularity problem, we derive new non-singular expressions of the first- and second-order derivatives of Schmidt SNALF, and the corresponding two kinds of spherical harmonic polynomials. When the novel expressions are applied to the traditional formulae of GVs and GGTs, more practical expressions of GVs and GGTs with non-singularity are formulated by refining the cases that the order m equals 0, 1, 2 and other values. Furthermore, to provide flexible calculation strategies for Schmidt SNALF, we derive four kinds of recursive formulae, including the standard forward row recursion (SFRR), the standard forward column recursion (SFCR), the cross degree and order recursion (CDOR), and the Belikov recursion (BR). Besides, we demonstrate the effectiveness of the new derived non-singular expressions of GVs and GGTs and analyze the computation speed and stability of the four recursive formulae of Schmidt SNALF by extensive numerical experiments. Results achieve significant improvements in solving the singularity problem of the SHEs of GVs and GGTs.

Visibility data are fundamental meteorological data widely used in many fields such as climate change, atmospheric radiation, atmospheric pollution, and environmental health. Calculating the average visibility is typically the first step when using visibility data. However, this study proves that the algorithm previously used to calculate average visibility is incorrect, leading to a non-negligible error in average visibility data. Moreover, the use of this incorrect algorithm not only artificially reduces the reliability of visibility data, but also affects the credibility and even the correctness of the conclusions reached in previous studies using visibility data. Therefore, we present the correct algorithm for average visibility, which should be applied to both future and previous research to significantly increase the reliability and application scope of visibility data.

Six sprites were observed on 22 July 2013 from Mt. Fuji (3776 m above sea level), Japan. Five of six sprite-producing positive cloud-to-ground strikes (SP +CGs) occurred in the stratiform region, while one SP +CG occurred in the convective region. Time sequences and horizontal evolution of precipitation between these regions with sprites were analyzed. Prior to the first five sprites, the areal amount of strong precipitation (≥8 mm/h) increased considerably. However, such an increase did not occur with the sixth sprite. The sprites occurred at the local peaks in strong precipitation rate with respect to total precipitation. The rise time to the first peak with the first sprite was 80 minutes, while the rise time to the last peak with the sixth sprite was 30 minutes. These temporal differences until peaks may indicate that the charging mechanisms due to precipitation are different between the stratiform and convective regions.

The frequency of extreme weather events depends relatively more on climate variability than on average changes. This makes variability a crucial element to consider in future projections. Stable water isotopes such as δ18O extracted from climate archives, including ice-cores, have been used to reconstruct regional climate and evaluate climate simulations. These archives have shown that variability in the Holocene is much lower than that at the Last Glacial Maximum (LGM, 21 kyr ago). However, state-of-the-art climate models still fail to simulate this shift. Comparison is difficult, since paleoclimate equilibrium simulations are typically run for few centuries and do not yet incorporate water isotope tracers. Volcanic eruptions offer a unique testbed to analyse the link between regional archives and global climate since well reconstructed aerosol data from 800 CE onward allow the investigation of small and large-scale effects in time and space on the climate. Here, millenial simulations from the isotope-enabled version of HadCM3 forced by solar and volcanic reconstructions in pre-industrial, LGM and past-millenium scenarios were evaluated. We then analysed the influence of volcanic eruptions on climate and δ18O values in polar and alpine regions. This allowed us to test the dependency of isotope values on regional shifts in climatology as well as global anomalies using composite analysis of volcanic eruptions. We finally discuss the impact of these results on the climatic representation of polar and alpine ice-cores representing changes in global climate variability.

Stick-slips are spontaneous, unstable slip events during which a natural or man-made system transitions from a strong, sticking stage to a weaker, slipping stage. Stick-slips were proposed by Brace and Byerlee (1966) as the experimental analogue of natural earthquakes. We analyze here the mechanics of stick-slips along brittle faults by conducting laboratory experiments and by modeling the instability mechanics. We performed tens of shear tests along experimental faults made of granite and gabbro that were subjected to normal stresses up to 14.3 MPa and loading velocities of 0.26-617 micron/s. We observed hundreds of spontaneous stick-slips that displayed shear stress drops up to 0.66 MPa and slip-velocities up to 14.1 mm/s. The pre-shear and post shear fault surface topography were mapped with atomic force microscopy at pixel sizes as low as 0.003 micron^2. We attribute the sticking phase to the locking of touching asperities and the slipping phase to the brittle failure of these asperities, and found that the fault asperities are as strong as the inherent strength of the host rock. Based on the experimental observations and analysis, we derived a mechanical model that predicts the relationships between the measured stick-slip properties (stress-drop, duration, and slip-distance) and asperity strength.

Surface tension controls all aspects of fluid flow in porous media. Through measurements of surface tension interaction under multiphase conditions, a relative permeability relationship can be determined. Relative permeability is a numerical description of the interplay between two or more fluids and the porous media they flow through. It is a critical parameter for various tools used to characterized subsurface multiphase flow systems, such as numerical simulation for oil and gas development, carbon sequestration, and groundwater contamination remediation. Therefore, it is critical to get a good statistic distribution of relative permeability in the porous media under study. Empirical relationships for determining relative permeability from capillary pressure are already well established but do not provide the needed flexibility in that is required to match laboratory derive relative permeability relationships. By expanding the existing methods for calculating relative permeability from capillary pressure data it is possible to create both two and three-phase relative permeability relationship. Existing laboratory measured relative permeability data along with mercury intrusion capillary (MICP) data coupled with interfacial tension and contact angle measurements were used to determine the efficacy of this approach to relative permeability curve creation. The relative permeability relationships determined with this method were fit to the existing laboratory data to elucidate common fitting parameters that were then used to create relative permeability relationships from MICP data that does not have an associated laboratory measured relative permeability relationship. The study was undertaken as part of the Southwest Regional Partnership on Carbon Sequestration (SWP) under Award No. DE-FC26-05NT42591.