Aging flood infrastructure systems will need to be closely monitored as metropolitan areas globally face increasing inundation risk from sea level rise. To augment traditional ground survey, synthetic aperture radar (SAR) is shown to efficiently quantify elevation change along earthen levees with continuous spatial coverage. The study area, California’s Sacramento-San Joaquin Delta, has an exemplar earthen levee system that protects the region from flooding. We investigate evidence of settling from historic levee breaks and small-scale subsidence features with a vertical velocity map and time-series of cumulative displacement derived from data acquired by the UAVSAR (Uninhabited Aerial Vehicle Synthetic Aperture Radar) L-band SAR, during 2009-2015. Comparison between radar and lidar maps (2007 and 2017) show that typical laser elevation surveys can miss subsidence features in the presence of normal maintenance activities. Historic levee break sites show more stable conditions due to the nature of repairs, and can be monitored using the SAR time series product. SAR information helps monitor the efficacy of repairs and targeted improvements to decrease the risk of levee breaks. In light of the upcoming NASA-ISRO SAR satellite mission, for which UAVSAR is the prototype, detailed monitoring will be attainable for levees worldwide.

The Amazon River discharges more than 200,000 m3 s-1 into the Western Tropical Atlantic Ocean from May to June. The low salinity surface plume extends more than 1800 km from the mouth and covers an area greater than 1 million square kilometers. We hypothesize that the plume exhibits distinct microbial community assemblages driven by plume age, nutrient supply, and light availability. We collected samples for nutrients and flow-cytometry measurements to investigate the spatial variability of the cyanobacteria Prochlorococcus spp. and Synechococcus spp., picoeukaryotes, and heterotrophic bacteria. Overall the surface salinity of the water we sampled ranged from 15.5 ppt at the southernmost station to 36.3 ppt in the open ocean station. The surface nitrate and soluble reactive phosphorus concentrations ranged from below detection limit to 3.3 µM and 2 µM, respectively. Generally, in the freshest surface plume waters (15-28 ppt) we found the highest abundances of Synechococcus spp., picoeukaryotes, and hetrotrophic bacteria with little or no Prochlorococcus spp. In the transition of surface salinities from 28 ppt to 32 ppt, a population of Prochlorococcus spp. began to form below the surface plume while Synechococcus spp. abundances at the surface remained unchanged and picoeukaryotes, and heterotrophic bacteria abundances decreased. As the surface salinity climbed over 32 ppt, the Prochlorococcus spp. abundance was uniformly high throughout the euphotic zone. On the other hand, as surface salinities increased over 32 ppt Synechococcus spp. abundances at the surface gradually decreased, while picoeukaryote and hetrotrophic bacterial abundances remained constant. We will discuss changes in the microbial community composition as a function of nutrient and light availability, as well as plume age in the Amazon Plume-Ocean continuum in both surface and deep chlorophyll maximum assemblages.

Local base-level change drives the transition of river morphology from one steady state to the new one. Although extracting tectonic information from river steepness assumes steady state, presence of knickpoints often complicates the stream profile analysis. This study aims to investigate the transient process of channel adjustment to tectonic perturbation using channel width, width to depth ratio, and normalized steepness index (θref=0.45). I focus on rivers along a normal fault in Iwaki, Fukushima, the eastern part of Japan. This fault ruptured on 11 April 2011, and the maximum vertical displacement was ~0.8 m. Paleoseismic trenches indicated that three surface-rupturing observed three types of rivers: one which is away from the fault and at old steady state, one which flows across the fault and at transient state characterized by a slope-break knickpoint, and one which flows across the fault and does not include any prominent knickpoints thus at new steady state. For a river at old steady state, channel width (W) increases with drainage area (A) (W~3.51A0.44), and width to depth ratio and steepness index are almost constant over the reach. For a river at transient state, width and width to depth ratio decrease at downstream of a knickpoint, and steepness index increases by a factor of two to four. For a river at new steady state, width, width to depth ratio, and steepness index show no discernible changes. Preliminary interpretation is that channel narrowing occurs after a channel starts steepening, and that channel width to depth ratio drops when a river is subjected to active deformation and becomes constant over an entire reach. Combining with ongoing field measurements, I will discuss the transient response of a river to tectonics.

The transition from sand ripples to megaripples encodes information about the physics of how both sand-sized (moved via saltation) and coarsegrained (moved via impact creep) particles interact under Martian conditions. Previous studies have focused on the aeolian mobility of sand on Mars; here we examine how mobile sand interacts with larger particles moved by creep. HiRISE images of small dunes (lacking well developed slip faces) on Mars reveal a transition of aeolian bedform scale with increasing distance from the dune. Here we document the particles in a similar transition on Earth. High Resolution Imaging Science Experiment (HiRISE) images have documented that sand is moving at many locations around Mars under current conditions. Unlike the active sand deposits, enigmatic “Transverse Aeolian Ridges” (TARs; the non-genetic term for linear to curvilinear aeolian bedforms resulting from either dune- or ripple-forming processes) are found at locations widely distributed across Mars. Recently bright TARs were documented to have moved in HiRISE images taken many Earth years apart at three widely separated locations. Great Sand Dunes National Park and Preserve (GSDNPP) in Colorado has a bimodal particle size distribution along with a seasonal bimodal wind regime, providing the setting to examine the transition from sand ripples (<1 cm in height) to megaripples (typically ~25 cm in height). A Smithsonian Scholarly Studies Award for FY19 funded trips to GSDNPP during May and September of 2019 to collect thousands of digital photographs of ripple-megaripple transitions that were later processed using Multiview Stereo Photogrammetry software to produce detailed Digital Terrain Models (DTMs). The digital images were obtained using a Nikon camera that was motor-driven along a track above the study area. The track was then manually advanced following each photo traverse. Photos were obtained using both a 35 mm lens and a 85 mm Macro lens. The DTMs clearly resolve individual coarse (1-2-mm diameter) particles on the bedforms, providing a detailed record of the surface distribution of coarse grains across both sand ripple and megaripple bedforms, including cases where the crests were continuous between sand ripples and megaripples.

Global warming is presently accelerating, raising the question whether all climate forcing and feedback mechanisms have been accounted for. Here a metabolic climate forcing and feedback mechanism is introduced, providing an explanation for the observed accelerated global warming. Based on more than 400,000 meteorological observations at various latitudes, it is shown that temperatures at the Earth's surface increasingly depart from thermodynamic equilibrium conditions towards warming at all examined geographical locations because of a long-lasting imbalance between the exothermic metabolic process of ecosystem respiration and the endothermic metabolic process of photosynthesis. Following the principles of the metabolic theory, metabolic imbalances are attributed to warmer temperatures stimulating ecosystem respiration at the same time as photosynthesis becomes light constrained. Since metabolic imbalances are expected to continue until ecosystem respiration becomes substrate limited, there is an urgent need to navigate climate mitigation towards measures that can slow down ecosystem respiration.

A sudden stratospheric warming (SSW) happened in September 2019 in the Southern Hemisphere (SH) with winds at 10hPa, 60°S reaching their minimum value on September 18. The evolution, favorable conditions, and predictability for this SSW event are explored. The favorable conditions include easterly equatorial quasi biennial oscillation (QBO) winds at 10hPa, solar minimum, positive Indian Ocean Dipole (IOD) sea surface temperatures (SST), warm SST anomalies in the central Pacific, and a blocking high near the Antarctic Peninsula. The predictive limit to this SSW is around 18 days in some S2S models, and more than 50% of the ensemble members forecast the zonal wind deceleration in reforecasts initialized around 29 August. A vortex slowdown in evident in some initializations from around 22 August, while initializations later than 29 August capture the wave-like pattern in the troposphere. The ensemble spread in the magnitude of the vortex deceleration during the SSW is mainly explained by the ensemble spread in the magnitude of upward propagation of waves, with an underestimated tropospheric wave amplitude leading to a too-weak weakening of the vortex. The September 2019 SH SSW did not show a near-instantaneous downward impact on the tropospheric southern annular mode (SAM) in late September and early October 2019. The Australian drought and hot weather in September possibly associated with the positive IOD might have been exacerbated by the negative SAM in October and later months due to the weak stratospheric polar vortex. However, models tend to forecast a near-instantaneous tropospheric response to the SSW.

Organic nitrates (RONO) are an important NO sink.  In rural environments dominated by biogenic emissions, nocturnal NO-initiated production of RONO is competitive with daytime OH-initiated RONO production.  However, in urban areas, OH-initiated production of RONO has been assumed dominant and NO-initiated production considered negligible.  We show evidence for nighttime RONO production similar in magnitude to daytime production during three aircraft campaigns in chemically-distinct environments: SEACRS in the rural Southeastern US, FRAPPÉ in the Colorado Front Range, and KORUS-AQ around the megacity of Seoul.  During each campaign, morning observations show RONO enhancements at constant, near-background Ox (≡ O + NO), indicating that the RONO are from a non-photochemical source, whereas afternoon observations show a strong correlation between RONO and O resulting from photochemical production.  We show there are sufficient precursors for nighttime RONO formation during all three campaigns.  This evidence impacts our understanding of the nighttime lifetime and fate of NO.

We report the design and results from a series of recent cruises using a fast vertical profiling autonomous underwater vehicle called Clio. Clio has been designed specifically to complement conventional wire-based sampling techniques—to improve ship-time utilization by operating simultaneously and independently of conventional techniques, and thereby to cost-effectively improve the understanding of marine microorganism ecosystem dynamics on a global scale. Life processes and ocean chemistry are linked: ocean chemistry places constraints on marine metabolic processes, and life processes alter the speciation, chemical associations, and water-column residence time of seawater constituents. Advances in sequencing technology and in situ preservation have made it possible to study the genomics (DNA), transcriptomics (RNA), proteomics (proteins and enzymes), metabolomics (lipids and other metabolites), and metallomics (metals), associated with marine microorganisms; however, at present these techniques require sample collection. For this purpose, Clio’s primary payload consists of two Suspended-Particle Rosette (SUPR) multi-samplers capable of returning up to 20 sets of filtered samples and filtrate per dive, and filtering up to 280 L of water per sample. Clio hosts additional profiling sensors consisting presently of a Seabird Electronics CTD, WET Labs combined chlorophyll and backscatter fluorimeter, and C-Star transmissometer. Since sea trials in 2017 Clio has participated in 5 cruises including most recently a section cruise between Bermuda and Woods Hole in June of 2019. On that cruise Clio executed a total of 9 nightly dives 12-16 hours in length and filtered a total of 20,878 L of seawater. The vehicle holds depth to a precision of better than 5 cm, is rated to 6000 m (4100 m maximum depth to date) and transits the water column at 45 m/min. Clio has demonstrated consistent reliable performance in its intended role; however, opportunities exist to further exploit its capabilities. Clio’s last two dives included autonomous data-driven selection of sample depths to better capture the deep chlorophyll maximum. Clio’s large payload capacity (10s W, 10s kg) could host novel samplers as well as in situ sample processors and other profiling instruments.

We analyze forty-seven best-quality, ten-year-long daily Global Positioning System (GPS) position time series of Taiwan, to understand the origin of the GPS’s common-mode error (CME) whose seasonality in the standard deviation evidences a meteorological origin. We employ the efficient Empirical Orthogonal Function analysis to extract the CME as the leading island-wide mode for all three components (whereas the second mode relates to the El Niño-Southern Oscillation). We find that the CME correlates well with the acquired variations in the atmospheric mass loading (AML) displacement field for Taiwan courtesy of NASA Goddard Space Flight Center for the vertical component with high coherence around 11-14 cycles per year. Further regression analysis shows that up to 90% of the non-seasonal AML displacements in Taiwan are evident in the CME variations.

Subsurface imaging is key to understanding the origin of intraplate volcanos. The Changbaishan volcano, located about 2000 km away from the western Pacific subduction zone, has several debated origins. To investigate this, we compared regional seismic tomography with the electrical resistivity results and performed high-resolution 1D and quasi-2D velocity-depth profiles. We show that the upper mantle is characterized by two anomalies exhibiting distinct features which cannot be explained by the same mechanism. We document a localized low-velocity anomaly atop the 410-km discontinuity, where the P-wave velocity is reduced more than that of the S-wave (i.e., low Vp/Vs). We propose that this anomaly is caused by the reduction of the effective moduli during the phase transformation of olivine. The other anomaly, located between 300 km and 370 km depth, reveals a significant reduction of the S-wave velocity (i.e., high Vp/Vs), associated with a reduction of the electrical resistivity, altogether consistent with partial melting.

The convective nature of Stratocumulus topped boundary layers (STBL) involves the motion of updrafts and downdrafts, driven by surface fluxes and radiative cooling, respectively. The balance between shear and buoyant forcings at the surface can determine the organization of updrafts between cellular and roll structures. We investigate the effect of varying shear at the surface and top of the STBL using LES simulations, taking DYCOMS II RF01 as a base case. We focus on spatial identification of the following features: coherent updrafts, downdrafts, and wet updrafts, and observe how they are affected by varying shear. Stronger surface shear organizes the updrafts in rolls, causes less well-mixed thermodynamic profiles, and decreases cloud fraction and LWP. Stronger top shear also decreases cloud fraction and LWP more than surface shear, by thinning the cloud from the top. Features with stronger top than surface shear are associated with a net downward momentum transport and show early signs of decoupling. Classifying updrafts and downdrafts based on their vertical span and horizontal size confirms the dominance of large objects spanning the whole STBL. Large objects occupy 14% of the volume in the STBL while smaller ones occupy less than 1%. For updraft and downdraft fluxes these large objects explain 33% of the vertical velocity variance and 53% of the buoyancy flux, on average. Stronger top shear also weakens the contribution of downdrafts to the turbulent fluxes and tilts the otherwise vertical development of updrafts.

Marine biological activities make substantial influences on aerosol composition and properties. The eastern China seas are highly productive with significant emissions of biogenic substances. Air mass exposure to chlorophyll a (AEC) can be used to indicate the influence of biogenic source on the atmosphere to a certain degree. In this study, the 12-year (2009–2020) daily AEC were calculated over the eastern China seas showing the spatial and seasonal patterns of marine biogenic influence intensity are co-controlled by surface phytoplankton biomass and boundary layer height. The AEC was linearly correlated with aerosol methanesulfonate (MSA) in each of three sub-regions, and the constructed parameterization scheme was applied to simulate the spatiotemporal variation of marine biogenic MSA. This AEC-based approach with observation constraints provides a new insight into the distribution of marine biogenic aerosols which may become increasingly important with the decline of terrestrial input to the studied region.

Tropical convection is known to self-organize under the diurnal cycle, yet is also subject to large scale convergence. In a suite of idealized numerical experiments we mimic Earth’s tropical circulation, to probe the cross talk between inherent circulation eigenmodes and the convective diurnal cycle — which generally are characterized by incommensurate oscillatory frequencies. The tropics are caricatured by a doubly-periodic domain with spatially constant surface temperature $T_S(x,y,t)$ in the “zonal” ($x$) but decreasing $T_S$ in the “meridional” dimension. Temporally, we contrast constant $T_S(x,y,t)=T_S(x,y)$ with diurnally varying $T_S(x,y,t)=T_S(x,y,t+\tau_d)$, with $\tau_d=1\,$day. We find that the diurnal forcing by no means dominates the precipitation power spectrum. Rather, the intrinsic circulation period $\tau_i$ drives temporal precipitation patterns for large and small domains. At intermediate domain sizes, where intrinsic frequencies approximately match the diurnal one, i.e., $\tau_i\approx \tau_d$, the diurnal cycle is amplified and, substantially increasing the precipitation amplitude.

Gravity Recovery And Climate Experiment (GRACE) and GRACE-Follow On (GRACE-FO) global monthly measurements of Earth’s gravity field have led to significant advances in the quantification of mass transfer on Earth. Yet, a long temporal gap between missions prevents interpretation of long-term mass variations. Moreover, instrumental and processing errors translate into large non-physical stripes polluting geophysical signals. We use Multichannel Singular Spectrum Analysis (M-SSA) to overcome both issues by exploiting spatio-temporal information of multiple Level-2 GRACE/GRACE-FO solutions. We statistically replace missing data and outliers using iterative M-SSA on Equivalent Water Height (EWH) time series processed by CSR, GFZ, GRAZ, and JPL to form a combined evenly spaced solution. Then, M-SSA is applied to retrieve common signals between each EWH time series and its neighbours to reduce residual spatially uncorrelated noise. We develop a complementary filter, based on the residual noise between fully processed data and a parametric fit to observations, to further reduce persisting stripes. Comparing GRACE/GRACE-FO M-SSA solution with SLR low-degree Earth’s gravity field and hydrological model demonstrates its ability to statistically fill missing observations. Our solution reaches a noise level comparable to mass concentration (mascon) solutions over oceans, without requiring \textit{a priori} information or regularisation. While short-wavelength signals are hampered by filtering of spherical harmonics solutions or challenging to capture using mascon solutions, we show that our technique efficiently recovers localized mass variations using well-documented mass transfers associated with reservoir impoundments.

The Brazilian National Institute for Space Research (INPE) produces research that helps to understand climate and weather dynamics in Brazil and in the world, with significant impacts on national public and private strategic planning. Among the essential information for the studies are the rainfall data. In this context, ensuring the quality of this data has a direct impact on the reliability of the forecasts and analysis generated from them. Thus, this study, which is a partnership between INPE, the Laboratory of Atmospheric Physics and Polytechnic School of USP and the ARM-DoE (Atmospheric Radiation Measurement Climate Research Facility), aimed to establish computational tools that could deal with the quality of data from rain in accordance with the main international directives. Thus, it was proposed for this study the development of a specific toolkit for data from the Micro Rain Radar (MRR), disdrometers PARSIVEL2 and RD80, and rain gauge that would help researchers from INPE, USP and partners to: standardize the preparation of raw data for internationally accepted formats; processing figures to support quick analyses; analyze and process data quality and, finally, record metadata and quality analysis for publication in international data repositories.

The study area is located in the Ferkessédougou belt in northern Côte d’Ivoire, precisely 30 km east of the city of Ferkessédougou. The aim of this study is to understand the tectonic which control gold mineralization. A combination of remote analysis and field mapping work, trenching, reverse circulation drilling hole, core drilling hole was carried out and finally laboratory work (microscopy). Different processing such as ACP, adaptive filters have been applied to Landsat 8 and Radarsat satellite images, in order to enhance information for better lineament extraction. Also, different complementary techniques (horizontal gradient, Euler deconvolution) were applied to the areomagnetic map in order to highlight the different lineaments. Four sets of lineaments have been producted by these images: N080-N100, N030-050, N000-N020, N120-N135.The validation of these different linear structures was made with field data. Thus, in the field, the metasediments show a strong S1 schistosity, stirikes NNE, with and dips towards the South-East, compatible with a D1 shortening episode. The emplacement of leucogranitic batholith and tonalite induces deformation (D2) which is shearing foliation S2. ). Later, diorite dykes induces the S3 shearing foliation. The earliest form of gold mineralization is located in quartz veins and fractures filled by sulphide ( pyrite). The second form of gold mineralization is disseminated and hosted in the sheared contacts betwween intrusive units with the metasediments. Studies show that quartz veins control the highest gold grades in tonalite unit. The mineralization of our study area is an IRGS type. Keywords: Gold, mineralization, Pyrite, Ferkessedougou, Ivory Coast.

Small transient stress perturbations are prone to trigger (micro)seismicity. In the Earth’s crust, these stress perturbations can be caused by various sources such as the passage of seismic waves, forcing by tides, or hydrological seasonal loads. A better understanding of the dynamic of earthquake triggering by stress perturbations is essential in order to improve our understanding of earthquake physics and our consideration of seismic hazard. Here, we study an experimental sandstone-gouge-filled fault system undergoing combined far field loading and periodic stress perturbations (of variable amplitude and frequency) at crustal pressure conditions. Microseismicity — in the form of acoustic emissions (AE) — strains, and stresses, are continuously recorded in order to study the response of microseismicity as a function of loading rate, amplitude and frequency of a periodic stress perturbation. The observed AE distributions do not follow the predictions of a Coulomb failure model taking into account both constant loading and oscillation-induced strain rates. A susceptibility of the system’s AE response to confinement pressure amplitude is estimated, which showcases a linear relation between confinement pressure amplitude and the AE response amplitude, observations which agree with recent higher frequency experimental results on dynamic triggering. The magnitude-frequency distribution of AEs is also computed. Oscillations in Gutenberg-Richter b-value are observed in experiment catalogues but are not quantified. Our experiments may help complement our understanding of the influence of low inertia stress phenomena on the distribution of seismicity, such as observations of dynamic triggering and seismicity modulation by solid earth tides or seasonal loading.

A document by Wei Zhang. Click on the document to view its contents.