The predicted increasing ground temperatures in the Arctic results in the deepening of the active layer and intensification of geochemical processes, which could affect the geochemical composition of surface waters. Determining the responses of the riparian soil systems to surrounding hydrological flows under changing climate conditions is important for understanding the seasonal changes in hydrological processes. Therefore, in this study, one soil core from the study area polygon rim (close to the Taz River, TA) and two soil cores from the riverain terrace (close to the Syoyakha River, SY and Murtyyakha River, MU) in Russian Western Siberia and their supra-permafrost water, adjacent stream flows and river water were sampled for analysis of geochemical elements. The results showed that most elements above their respective detection limits (Mn, Sr, Fe, Mg, Cr, Co, V, Pb, Al and Ca) started to accumulate in the downwards gleyed layer during September–October in response to the deepest thaw in the active layer. This study focused on the highly mobile elements, i.e., Mn, Ca, Mg, Al and Ti, in the deepest layer; and found the transport of organic matter in the upper layer carried these elements to both surface water ponds/flows and supra-permafrost water, and further, to the rivers. The best linear correlation for both stream flows and river water were Mn, which may be a proxy for predicting the processes occurring within the active layer during the annual summer-autumn thaw. Finally, landscapes with different ice contents may experience changes in the elements transported to surface waters.

Traditionally, the Saharan Air Layer (SAL) is defined as an elevated dry layer, frequently containing mineral dust transported from North Africa. The presence and characteristics of the SAL have an impact on tropical Atlantic climate and also on tropical cyclone development. However, recent observations from airborne campaigns in the Eastern Tropical Atlantic have found that under heavier dust loadings, water vapor content is increased in the SAL, rather than decreased as expected. This work will present airborne in-situ profile observations of dust loading and water vapor in the SAL from the AER-D field campaign during August 2015 in the tropical East Atlantic. The radiative impact in the shortwave and longwave spectra of the enhanced water vapor in the SAL will quantified and compared to that from mineral dust in the SAL. Trends in SAL water vapor over recent decades from satellite observations will be presented to assess the representativity of the aircraft data.

Climate contrasts across drainage divides, such as orographic precipitation, are ubiquitous in mountain ranges, and as a result, mountain topography is often asymmetric. During glacial periods, these climate gradients can generate asymmetric glaciation, which may modify topographic asymmetry and drive divide migration during glacial-interglacial cycles. Here we quantify topographic asymmetry caused by asymmetric glaciation and its sensitivity to different climate scenarios. Using an analytical model of a steady-state glacial profile, we find that the degree of topographic asymmetry is primarily controlled by differences in the equilibrium line altitude (ELA) across the divide. Our results show that glacial erosion can respond to the same climate asymmetry differently than fluvial erosion. When there are precipitation differences across the divide, glacial erosion produces greater topographic asymmetry than fluvial erosion, all else equal. These findings suggest that glaciations may promote drainage reorganization and landscape transience in intermittently glaciated mountain ranges.

Hydropower plants and large storage reservoirs upstream of water-dependent power plants represent physical assets with a substantial role in the function of both river and power grid systems. Hydropower has the potential to play an important role in decarbonization strategies as a means to achieve reliability and resilience in an increasingly complex grid; for example, as a means to offset variability in other renewable resources and provide long term energy storage. The power grid and river systems are interlinked through hydropower plants, resulting in hydropower operators needing to balance potentially competing interests of water management, as well as power demands. Despite this multisectoral dependency, the representation of hydropower in power system resource adequacy studies typically differs from the representation in water management adaptation studies, especially at the regional scale. The objective of this presentation is to clarify the concept of hydropower flexibility (and adaptation) in a way that can bridge gaps between the tools used by and expectations of water managers, hydropower operators and power system operators. The developed qualitative multisystem, multiscale approach to hydropower flexibility can be leveraged to highlight the value, facilitate the compatibility and complementarity, and inform on the generalization of technology innovation and climate change adaptation strategies.

Vertical motions associated with mesoscale ocean eddies modulate the light and nutrient environment, stimulating anomalies in phytoplankton biomass and chlorophyll. Phytoplankton populations can be subsequently trapped by the horizontal circulation or laterally diluted. In a time-varying flow, Lagrangian methods can be used to quantify eddy trapping, also known as Lagrangian coherency. From two decades of remote sensing observations in the North Pacific Subtropical Gyre, we compared coincident Eulerian and Lagrangian eddy atlases to assess the impact of eddy trapping on chlorophyll concentration. We found higher chlorophyll within Lagrangian coherent boundaries than in Eulerianeddies and outside-eddy waters. Yet, there are differences regionally and seasonally. For example, chlorophyll is most enriched within coherent boundaries of the Hawaiian Lee eddies and to the south of 23N in fall and winter. Our results suggest that by not accounting for lateral dilution, Eulerian analyses may underestimate the role of mesoscale eddies in enhancing chlorophyll.

During COVID-19 pandemic in 2020, many cities and areas were shutdown to control the virus spread. The shutdown introduced reduced emissions from vehicles and power plants. In this study, we studied the impact on pollution by analyzing Suomi NPP satellite Visible Infrared Imaging Radiometer Suite (VIIRS) aerosol optical depth (AOD); AOD is a proxy for particulate pollution in the atmosphere. The investigation is performed over several areas and cities around the globe, i.e. China, India, Europe, the United States, New York city, Los Angeles, etc. In general, reductions in AOD compared to the previous years are found in these areas but with some differences. In China, where the pollution in general is high than the other areas, the reduction in AOD is the most obvious. However, in Europe and the United States, the reduction in AOD is less obvious. In India, the effect is in between. Comparing reductions in S5P Tropospheric Ozone Monitoring Instrument (TROPOMI) nitrogen dioxide (NO2) and AOD, we found that they sometimes co-vary and sometimes do not. The possible reason is that NO2 and aerosols do not have the same life time and therefore may not always co-exist at the same time and place. NO2 has a shorter life time and therefore tends to be observed close to the source region. Because of longer life time of aerosols, the aerosols from smoke, dust, and pollution can be transported with long distance and interfere with those from local sources. To tease out the AOD reductions from lockdown compared to business as usual (BAU), AOD data were analyzed using NO2 as a filter. Using this approach we found marginal reductions to particulate pollution in some regions to reductions of up to 20% in other regions. Analysis of particulate pollution in 2020 compared to BAU globally and regionally will be presented.

Tectonic information available from remote seismometers is compromised by uncertainties in epicenter and depth, which often prevent earthquakes being associated with faults observable in morphologic data. Here we show that careful study of regional recordings can achieve reasonable position and, for the larger events, also depth estimates. We illustrate this with swarms totallying 90 earthquakes of 3.6 mb to 5.5 Mw recorded at coastal stations of the Brazilian Seismographic Network, GSN, GEOSCOPE and Cape Verdes. Seismicity occured in 4 swarms, firstly in 2012 with 7 events in the valley floor and eastern wall near the ridge-transform intersection (4.05º-4.2ºN). Next, five events occurred in 2014, with three in the inner floor (4.8º-4.9ºN) and two under the valley wall (4.7º-4.8ºN). A 70-earthquake swarm in 2016 occurred in the 4.4º-4.8ºN valley floor, in both walls and floor, involving slip on different faults. The last 8 events in 2019 were located outside the median valley near a volcanic seamount. We estimated focal depths of the strongest events with Mw > 5.4 using waveform modeling and focal mechanims reported by the Global Centroid-Moment-Tensor Project. Our best estimated hypocenters lie 5-8 km beneath the seafloor, in keeping with maximum depths typically found with OBSs on the MAR. In contrast, deeper events (10 km) have been found in an OBS experiment around an active detachment fault elsewhere. Multibeam sonar data from the area do reveal a detachment fault surface (“megamullion”), but it ends 10-15 km from the median valley floor, suggesting that it is probably inactive. Although our uncertainties still do not allow the event depths to be discriminated from 10 km, our best estimates are more compatible with shallower normal faulting. Over time, repeating this exercise with many such datasets and comparing with morphologic data should help to resolve the incidence of deeper ruptures associated with detachment faults.

Ocean heat analyses of the North Atlantic Ocean based on the new high-resolution Northwest Atlantic (NWA) Regional Climatology (RC) developed at the NOAA’s National Centers for Environmental Information (NCEI) revealed decadal variability of the Eighteen Degree Water (EDW) depth that may be instrumental for understanding the localized heat accumulation in the NWA. The EDW is an important element of the Northwest Atlantic heat balance and an indicator of the ocean-atmosphere interaction in this region. The EDW deepening, or “heaving”, on decadal timescales are most likely caused by increasing Ekman pumping due to changes in the wind stress curl pattern over the NWA. The NCEI’s NWARC has also revealed that the highest rates of heat gain occur in the Sargasso Sea, southeast of the Gulf Stream path in the region occupied by the EDW. The volume of EDW depends on many factors, of which the most important are: Ekman pumping, heat fluxes at the air-sea surface, and heat advection within the Gulf Stream and the subtropical recirculation gyre. However, heat accumulation in several “pockets” southeast of the Gulf Stream and its extension seem to be most closely connected to EDW heaving. The depths of EDW for two independent ~30-year periods and their differences were computed and analyzed in conjunction with the changes in the curl of wind stress. As the comparison between the EDW depths mapped on three different spatial grids with 1°x1°, 1/4°x1/4°, and 1/10°x1/10° resolutions illustrate, the grid resolution does matter for mapping EDW on decadal timescales. The 30-year climate shift of the EDW depths between 1985-2010 and 1955-1984 compares quite well with the climatic shift in Ekman vertical velocities derived from the changes in the wind stress curl over the same time period. Comparing the eddy-permitting EDW heaving inferred from the NCEI’s NWARC and the ~30-year shift of the curl of wind stress, and consequently Ekman pumping, confirms a strong resemblance of the eddy-permitting and eddy-resolving EDW heaving patterns with two tightly localized pockets of heat accumulation southeast of the Gulf Stream and its extension.

A document by Brendan Godwin. Click on the document to view its contents.

Variability in the position and strength of the subtropical jet (STJ) and polar front jet (PFJ) streams has important implications for global and regional climate. Previous studies have related the position and strength of the STJ to tropical thermodynamic processes, whereas the position and strength of the PFJ are more associated with mid-latitude eddies. These conclusions have largely resulted from studies using idealized models. In this study, ERA-Interim reanalysis and CMIP6 global climate models are used to examine month-to-month and interannual variability of the wintertime Northern Hemisphere (NH) STJ and PFJ. This study particularly focuses on the regional characteristics of the jet variability, extending previous studies on zonal-mean jet streams. Consistent with idealized modeling studies, a close relationship is found between tropical outgoing longwave radiation (OLR) and the STJ, and between mid-latitude surface temperature gradients and the PFJ. Variations of both jets are also linked to well-known teleconnection patterns. Variations in tropical convection over the Pacific Ocean are associated with variations of the NH STJ at most longitudes, with different phases of the El Niño-Southern Oscillation (ENSO) associated with the shift and strengthening of the STJ in different regions. CMIP6 models generally capture these relationships, but the models’ tropical convection is often displaced westward when compared to observations, reflecting a climatological bias in OLR in the western tropical Pacific Ocean in many models. The displaced tropical convection in models excites different paths of Rossby wave propagation, resulting in different ENSO teleconnections on the STJ over North America and Europe.

Mammals, including humans and mice, employ V(D)J recombination and somatic hypermutation (SHM) to diversify their immunoglobulin (Ig) variable region repertoires, while domestic poultry, such as chickens and ducks, rely heavily on gene conversion (GCV) to achieve this diversification. Given the differences in the arrangement of Ig gene loci between chickens/ducks and humans/mice, we posited that the structural arrangement of the Ig locus might play a pivotal role in driving the pronounced frequency of GCV in poultry. To test this hypothesis, we engineered a novel mouse model, Igλ -/-Igκ -/-DIgL, characterized by the incorporation of the entire duck IgL gene locus and the simultaneous absence of the mouse endogenous IgL locus. These transgenic mice produced chimeric antibodies comprising mouse heavy chains and duck light chains, thereby offering partial support for B cell development. However, when subjected to repeated immunization with a variety of antigens, the humoral immune response in Igλ -/-Igκ -/-DIgL mice was notably diminished compared to that in wild-type mice. High-throughput sequencing of IgL repertoires unveiled distinct differences between Igλ -/-Igκ -/-DIgL mice and ducks in terms of V gene utilization frequencies, characteristics of the CDR3 region (CDRL3), and nucleotide additions at junctions (NP nucleotides). Despite the increased expression of duck IgL due to the absence of endogenous mouse IgL, the level of GCV observed in duck IgL of Igλ -/-Igκ -/-DIgL mice (2.01%) remained significantly lower than that in ducks (35.3%). These findings collectively indicate that the structural configuration of the Ig locus may not be a critical determinant of GCV and provide valuable insights into the mechanisms underpinning the high frequency of GCV observed in poultry species.

In recent decades, the intensity, frequency, and variability of extreme events (e.g., heat waves, droughts, severe storms, and floods) have increased globally due to the intensification of the changing climate, land-use/landcover and anthropogenic activities. An increase in extreme events results in severe economic crises and enormous disruptions in various social and environmental sectors. Hence, effective and efficient prediction and mitigation of flood and drought events are desirable. It requires a better understanding of the recent trends and variability of the extremes, which is quite challenging owing to the complex and non-stationary behaviour of the associated covariates (hydroclimatic variables, atmospheric circulation patterns), and their spatiotemporal variability and nonlinear interactions. This study proposes a new Non-stationary Standardized Potential Evapotranspiration Index (NSPEI) to assess the wetness and dryness condition and couples it with an entropy-based measure to quantify the variability of the extremes. NSPEI considers non-stationarities of both precipitation and temperature in addition to their ability to identify extreme events at different time/accumulation scales (multi-scalar). Hence, water deficits/excess could be better assessed over different accumulation periods, which helps identify and monitor various droughts (e.g., agricultural, meteorological) and water saturation conditions (e.g., floods, runoff). Furthermore, as the drought/wetness triggering variables and causes for extreme conditions may vary worldwide, a standardized drought variability index is introduced in this study to assess better drought and wetness variability across the world at multiple timescales (monthly, seasonal, annual and decadal). In addition, the influence of LULC and location indicators (latitude, longitude, and elevation) on drought and wetness variability is assessed across different continents for various time scales and severity of both wetness and dryness conditions. The analysis and outcomes of this study enhance understanding of global drought and wetness variability patterns and provide reliable information on water availability for devising effective water management strategies towards mitigation of the extremes in various continents.

A document by Marina Ruiz Sánchez-Oro. Click on the document to view its contents.

Lakes and wetlands are natural sources and have an important role for hydrological cycle. They are also affected by climate change and anthropogenic activities such as precipitation regime, diminishing water bodies, uncontrolled groundwater extraction, drainage and irrigation channels, agricultural activities and discharge of domestic and industrial waste. For this reasons monitoring the lake surface areas are very crucial. In this paper; the Seyfe Lake was selected as a case study. The study area is located at the southern part of the Seyfe basin with a catchment area of 1447 km2 in Central Anatolia. Seyfe Lake wetland is located in a closed basin. The lake area and its surroundings is a Ramsar site and have the status of Grade 1 Natural Site and Protected Natural Area. This study aimed to evaluate the spatio-temporal changes of the surface area of Seyfe Lake by using Geographical Information Systems (GIS) and remote sensing techniques. For this purpose Landsat (MSS, TM, ETM+, OLİ/TIRS) satellite images used for a period between 1987 and 2020. A total of 34 images were processed and, using unsupervised classification method, water body was extracted according to the spectral information of the image bands and the historical change of the lake surface area was calculated by using Image Analysis Function of ArcGIS 10.6.1 software. In addition to these satellite images, long-term hydrometeorological data and field observations were analyzed to determine the changes of the Seyfe Lake surface area and understand the effects of climate change and antropojenic activities. According to the old and recent satellite images of Seyfe Lake area, the persisting shrinkage of lake area and diminishing of the water resources over the years in the Seyfe Lake basin still continue. Maximum and minumum surface area of the lake was calculated 43 km2 and 18 km2 respectively during 1987-2020. In August 2008; the lake area is completely dried. Nowadays the 58% of the lake area is dried up. These variations could probably be related with the antropogenic effects and climatic changes in the study area. As a result, Satellite based techniques might provide a historical data to identify changes on the lake surface area. Remote sensing techniques are also effective to evaluate temporal and spatial changes on water resources resulted by human activities and local climate change. In-situ observation and hydrogeological monitoring are another important tools to support findings of remote sensing study. Keywords: Spatio-temporal change, Wetland, Seyfe Lake, Unsupervised Classification, Remote Sensing

Cover crops may influence soil health and functioning. However, little is known about the role of belowground root architectural traits in linking cover crop diversity with rhizosphere soil ecosystem properties. We hypothesize that cover crop diversity may improve root traits, which in return, could influence its effects on essential indicators of soil physicochemical heterogeneity, such as the composition of soil aggregate-size classes and nutrients, the soil organic matter (SOM) and soil organic carbon (SOC) contents, and microbial communities. We studied the impact of cover plant diversity on root traits, soil properties and microbial communities. The four soil aggregate-size classes, such as large macro- (>2000μm), small macro- (<2000-500μm), meso- (<500-250 μm), and micro-aggregates (<250 μm) were separated by the dry sieving. Root traits such as surface area (cm2) and length (cm) were quantified by image analysis using Winrhizo. The soil nutrient, SOM, and SOC contents were determined by standard methods. Plant diversity improved productivity, root architectural traits, composition of soil aggregate-size classes and nutrients, SOM and SOC contents, composition and networking of microbial communities. Our results suggest that competition among plant roots in species-rich than poor communities may improve rhizosphere soil carbon storage, composition of soil aggregate-size classes and microbial communities.

Observing the environment in the vast inaccessible regions of Earth through remote sensing platforms provides the tools to measure ecological dynamics. The Arctic tundra biome, one of the largest inaccessible terrestrial biomes on Earth, requires remote sensing across multiple spatial and temporal scales, from towers to satellites, particularly those equipped for imaging spectroscopy (IS). We describe a rationale for using IS derived from advances in our understanding of Arctic tundra vegetation communities and their interaction with the environment. To best leverage ongoing and forthcoming IS resources, including NASA’s Surface Biology and Geology mission, we identify a series of opportunities and challenges based on intrinsic spectral dimensionality analysis and a review of current data and literature that illustrates the unique attributes of the Arctic tundra biome. These opportunities and challenges include thematic vegetation mapping, complicated by low-stature plants and very fine-scale surface composition heterogeneity; development of scalable algorithms for retrieval of canopy and leaf traits; nuanced variation in vegetation growth and composition that complicates detection of long-term trends; and rapid phenological changes across brief growing seasons that may go undetected due to low revisit frequency or be obscured by snow cover and clouds. We recommend improvements to future field campaigns and satellite missions, advocating for research that combines multi-scale spectroscopy, from lab studies to satellites that enable frequent and continuous long term monitoring, to inform statistical and biophysical approaches to model vegetation dynamics.

The global distribution of high Remote-sensing reflectance (Rrs) waters visible from satellite, likely associated with coccolithophore blooms, has changed markedly over the past 40 years. Over that period there has globally been an overall decrease in bloom area of 1.15 million km2 but with notable Rrs increases in the Barents Sea and the Antarctic Ocean. The primary drivers of these fundamental changes to ocean biogeochemistry have been investigated using Machine Learning techniques together with contemporaneous global multi-decadal time-series of sea-surface temperature (SST); wind speed and stress; sea level anomaly (SLA); photosynthetically available radiation (PAR) and; mixed layer depth (MLD). When split into ocean provinces different drivers of positive and negative trends in Rrs were found to dominate in different regions, but generally increases were found to coincide with changes to SST, PAR and reductions to wind-speed.

Mineral hazards are a common, yet often less-recognized group of features compared to other types of natural and man-made hazards. We define “mineral hazards” in part as minerals and elements that occur naturally in elevated, potentially harmful, concentrations in rocks, soils, and certain fluids. Also included are features from human activities related to extraction of mineral and energy resources. Along with its large human population, extensive development, and diverse natural environment, California is very complex geologically, thus it contains many areas of mineral hazards that make it appropriate for such a study. Although mineral hazards have been investigated over several decades by the California Geological Survey (CGS), no systematic statewide assessment had been accomplished until recently when, at the request of the California Department of Transportation (Caltrans), the CGS completed a preliminary assessment of potential mineral hazards over the entire state. This work focused on natural and man-made minerals-related features that might adversely affect construction, use, and maintenance of state and federal highways under Caltrans jurisdiction. The features evaluated include: 1) geologic units that may contain naturally-occurring asbestos (NOA), fibrous erionite, or elevated concentrations of regulated metals (Ag, Ba, Be, Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, Tl, V, Zn) and metalloids (As, Sb, Se); 2) faults, which can be sites of increased potential for certain types of mineralization; 3) mines and prospects, which can be sources of anomalous concentrations of metals and ore-processing chemicals; 4) oil and natural-gas seeps; 5) thermal springs and fumaroles; and 6) oil, natural-gas, and geothermal wells. The methods and products developed during the Caltrans study can be applied worldwide to many other uses besides highways where there are obligations to protect public health and safety and the environment. The products include maps that highlight types and locations of potential mineral hazards, digital data in GIS format, and accompanying reports that provide details and additional information. Although they do not indicate risk or probability, these products can be applied by users from many backgrounds as screening tools to assess potential for the presence of mineral hazards.