Recently intensified forest fires in the Amazon region have led to large-scale forest losses, particularly in Brazil, after more than a decade of effective forest conservation policy. Analysis of the time course of fire impacts on water and carbon cycling is required for accurate measurement of changes in the forest-atmosphere interactions. Moreover, measurements must also account for natural variations associated with vegetation phenology, and generally direct and indirect effects of environmental changes at annual, seasonal and sub-annual time scales. Here, we study the recovery of two contrasting terra firme forests affected by fire in eastern (sub-montane ombrophile forests) and western (bamboo dominated forests) Amazonia in terms of water and carbon fluxes utilizing remote sensing (Moderate Resolution Imaging Spectroradiometer, MODIS) and climate reanalysis data (Global Land Data Assimilation System, GLDAS). Our results showed that fires significantly increased land surface temperature and air temperature in the forests over different time scales. However, the forests showed an ability to recover their original states in terms of coupling between the carbon and water cycles based on the comparison of the periods before and after the fires. Results from a wavelet analysis showed an intensification in annual and seasonal fluctuations, and in some cases (e.g., evapotranspiration) sub-annual fluctuations. Understanding the mechanisms controlling the forest-atmosphere interactions are essential for assessing how forest fires will influence the exchanges of water and carbon in the future. Improving data and theory about the impacts of fire and other disturbances on the energy balance is essential to improve earth systems models for forecasting the role of tropical forest fires in climate change. Within this context, our approach and, consequently, the results obtained here will help improve the understanding of how fires in terra firme Amazonian forests impact land-atmosphere coupling at different spatial and temporal scales.

Using Mars Atmosphere and Volatile Evolution observations, we characterize the variability of water vapor in the Martian thermosphere during Mars Years 32-35. Near a fixed atmospheric pressure level of ~5 × 10-7 Pa, the typical water density is 1.3 (±0.8) × 103 cm-3 and the typical water mixing ratio is 10 (±6) ppm. Thermospheric water levels are higher during the southern spring and summer seasons when Mars is near perihelion and there is significant dust loading in the lower atmosphere. However, the seasonal variation is not the same from year-to-year, likely due annual differences in dust loading. Water vapor is highly correlated with lower atmospheric dust, and increases during both regional and global dust storms. Our results support previous work that found increased dust levels allow more water to be supplied directly to the thermosphere.

Understanding fate and transport within fluvial systems requires accurate modeling of breakthrough curve (BTC) tails, which often display non-Fickian behaviors. However, it is unclear how anomalous processes relate to the physical and biological characteristics of the stream ecosystem. We use the Stochastic Mobile Immobile model (SMIM) to determine the impact of biofilm colonization among different substrate types on reach-scale transport velocity (V) and dispersion (D), rate of delivery to the subsurface (Λ), and retention within the subsurface (reflected by power law slope; β). During summer 2020 and 2021, we conducted a total of n=42 Rhodamine-WT releases in four experimental streams lined with contrasting substrata (sand, pea gravel, cobble, and a three-way mix) at the Notre Dame Linked Experimental Ecosystem Facility (ND-LEEF) in Indiana (USA). To explore the effect of biofilm colonization, we conducted releases under artificially shaded, early and late biofilm development, and senescent biofilm conditions. We found that replicated releases under constant conditions consistently reproduced stream BTCs and modeled transport parameters. Biofilm abundance, biofilm status (living versus dead), and substrate type produced significant variations in BTC shape and transport parameterizations. We found a non-linear relationship between algal biomass and V, where increases in biomass produced decreases in V at low biomass and increases in V at high biomass. Substrate type also predicted patterns in transport, with sand producing higher V, Λ, and β than larger substrata. These results suggest that substrate type acts as the primary driver and biofilm development the secondary control on transport in fluvial systems.

NASA’s Capacity Building Program (CBP) works to empower communities around the globe to use Earth observation data and products in their decision making. Working through program and element activities, CBP developed a theoretical framework for engagement focused around user needs which identifies the appropriate path for engagement based on geography, discipline, data needs and availability, depth of support required, partnerships involved, length of engagement, and desired outcomes. These decision factors would determine which CBP element would take on the effort – ARSET, DEVELOP, or SERVIR, and which approach would be implemented – trainings or co-development. Each approach offers participants different benefits and leads to outcomes that fall on a spectrum from increased awareness to sustained use of Earth observations. However, implementation of this framework across multiple programs with differing constraints has been challenging. This presentation will highlight the CBP framework and its user-centric approach, capacity building methods and incentives, metrics and tracking indicators, challenges, and lessons learned.

The existence of causal constraints introduces a temporal selection effect in the type of technosignatures that we can detect. I discuss the implications of this fact on the characteristic of detectable technosignatures, and in particular their longevity.

The Karakoram fault is an important strike-slip boundary for accommodating deformation following the India-Asia collision. However, whether the deformation is confined to the crust or whether it extends into the mantle remains highly debated. Here, we show that the Karakoram fault is overwhelmingly dominated by crustal degassing related to a 4 He-and CO 2rich fluid reservoir [e.g., He contents up to ~1.0−1.6 vol.%; 3 He/ 4 He = 0.029 ± 0.016 R A (1σ, n = 50); CO 2 /N 2 up to 3.7−57.8]. Crustal-scale active deformation driven by strike-slip faulting could mobilize 4 He and CO 2 from the fault zone rocks, which subsequently accumulate in the hydrothermal system. The Karakoram fault may have limited fluid connections to the mantle, and if any, the accumulated crustal fluids would efficiently dilute the uprising mantle fluids. In both cases, crustal deformation is evidently the first-order response to strike-slip faulting.

This paper presents the results of modeling the lower ionosphere response to solar X-ray flares of C-, M- and X-classes. The model is based on a 5-component scheme of the ionization-recombination cycle of the ionospheric D-region. Input parameters of the plasma-chemical model under different heliogeophysical conditions corresponding to selected X-ray flares were determined by using data received from AURA, SDO and GOES satellites. Verification of the obtained results was carried out with use of ground-based radiophysical measurements taken at the geophysical observatory Mikhnevo. Results of comparing the calculated and experimental the radio wave amplitude variations along six European very low frequency (VLF) paths show that the root mean square error (RMSE) does not exceed 1.5 dB for ~70% of cases including X-class flares during which the amplitude jump on some paths reaches 8 dB. Qualitative and quantitative analysis of the verification results of the VLF signal amplitude has showed the good predictive capability of the built model for describing weak and moderate ionospheric disturbances.

To clarify the impact of basal melting of the Antarctic ice sheet and biological productivity on biogeochemical processes in Antarctic coastal waters, concentrations of dissolved inorganic carbon (DIC), total alkalinity (TA), inorganic nutrients, chlorophyll a, and stable oxygen isotopic ratios (δ18O) were measured from the offshore slope to the ice front of the Totten Ice Shelf (TIS) during the spring/summer of 2018, 2019, and 2020. Off the TIS, modified Circumpolar Deep Water (mCDW) intruded onto the continental shelf and flowed along bathymetric troughs into the TIS cavity, where it met the ice shelf base and formed a buoyant mixture with glacial meltwater. Physical oceanographic processes mostly determined the distributions of DIC, TA, and nutrient concentrations. However, DIC, TA, and nutrient concentrations on the surface of the ice front were decreased by photosynthesis and the dilution effect of meltwater from sea ice and the base of the ice shelf. The partial pressure of CO2 (pCO2) in surface water was reduced by photosynthesis and dilution, and the surface water became a strong CO2 sink for the atmosphere. The DIC and TA (normalized to salinity of 34.3 to correct for dilution effects) changed in a molar ratio of 106:16 because of phytoplankton photosynthesis. The decrease of pCO2 by more than 100 μatm with respect to mCDW was thus the result of photosynthesis. The nutrient consumption ratio suggested that enough iron was present in the water column to supply the surface layer via buoyancy-driven upwelling and basal melting of the TIS.

In the field of geophysical exploration, fault identification is an important part. However, Due to the fixed identification mode, conventional computing methods cannot adapt to complex fault characteristics and environmental noise; And, the convolution neural network is prone to loss of global information because the slow convergence of global information. For those reasons, the previous fault identification methods cannot achieve higher resolution and accuracy fault identification, such as the identification results are very coarse, the identification results are inaccurate and results are discontinuous, especially in the case of severe environmental noise and complex fault interlacing. So in order to solve these problems, we proposed a deep learning network based on Transformer with improved window mechanism. Starting from the features of the data itself, quickly gather global information, and results on field data show that our network effectively solve the above problems. This work has positive significance for high-precision exploration work.

North Atlantic sea surface temperatures (NASST), particularly in the subpolar region, are among the most predictable locations in the world’s oceans. However, the relative importance of atmospheric and oceanic controls on their variability at multidecadal timescales remain uncertain. Neural networks (NNs) are trained to examine the relative importance of oceanic and atmospheric predictors in predicting the NASST state in the Community Earth System Model 1 (CESM1). In the presence of external forcings, oceanic predictors outperform atmospheric predictors, persistence, and random chance baselines out to 25-year leadtimes. Layer-wise relevance propagation is used to unveil the sources of predictability, and reveal that NNs consistently rely upon the Gulf Stream-North Atlantic Current region for accurate predictions. Additionally, CESM1-trained NNs do not need additional transfer learning to successfully predict the phasing of multidecadal variability in an observational dataset, suggesting consistency in physical processes driving NASST variability between CESM1 and observations.

This study explores geomorphology within canyons using 3D seismic imaging. It reveals crucial insights that underscore the relationship between growth faults, slope instability, and canyon development. The structural settings of canyons, often conforming to established patterns, come to light as integral components of the study. An important observation was made: the gradient, a first-order factor, exerts significant control over both canyon initiation and propagation. Furthermore, the distribution of growth faults, a major catalyst for slope instability, holds an indirect yet profound link to sediment routing within canyons and the ancient geography of the region. These findings not only enhance our understanding of canyon evolution but also play a crucial role in interpreting reservoir distribution, marking them as invaluable assets in some geological exploration and reservoir management. 

The Klamath Mountains in northern California and southern Oregon are thought to record 200+ m.y. of subduction and terrane accretion, whereas the outboard Franciscan Complex records classic ocean-continent subduction along the North American margin. Unraveling the Klamaths’ late history could help constrain this transition in subduction style. Key is the Mesozoic Condrey Mountain Schist (CMS), comprising, in part, a subduction complex that occupies a structural window through older, overlying central Klamath thrust sheets but with otherwise uncertain relationships to other, more outboard Klamath or Franciscan terranes. The CMS consists of two units (upper and lower), which could be correlated with 1) other Klamath terranes, 2) the Franciscan, or 3) neither based on regional structures and limited extant age data. Upper CMS protolith and metamorphic dates overlap with other Klamath terranes, but the lower CMS remains enigmatic. We used multiple geochronometers to constrain the timing of lower CMS deposition and metamorphism. Maximum depositional ages (MDAs) derived from detrital zircon geochronology of metasedimentary rocks are 153-135 Ma. Metamorphic ages from white mica K-Ar and Rb-Sr multi-mineral isochrons from intercalated and coherently deformed metamafic lenses are 133-116 Ma. Lower CMS MDAs (<153 Ma) predominantly postdate the age of other Klamath terranes, but subduction metamorphism appears to predate the earliest coherent Franciscan underplating (ca. 123 Ma). The lower CMS thus occupies a spatial and temporal position between the Klamaths and Franciscan and preserves a non-retrogressed record of the Franciscan Complex’s early history (>123 Ma), otherwise only partially preserved in retrogressed Franciscan high grade blocks.

The measurement and processing of high frequency acoustic backscatter profiles at multiple frequencies is an established technique for measuring suspended sediment load and equivalent mean particle size through the water column. The technique relies on the fact that the intensity of sound scattered by suspended particles is related not only to the particle size, but also the incident acoustic frequency. It is exploited by compact instruments that are deployed on seabed frames, vessels, and in laboratory flumes. However, one of the most significant influences on measurement accuracy comes from the presence of bubbles in the water column. Often found in suspended sediment study areas such as shallow wave-affected waters or highly turbulent flows, they can be of comparable acoustic cross-section to the suspended sediment particles and may dominate backscatter. Acoustic backscatter instrument calibrations and experimental measurements are typically carried out in a recirculating suspended sediment tower where, through careful design, a near homogeneous suspension can be established. Great attention is paid to the choice of fittings and recirculating pumps to ensure that no air is introduced into the flowing liquid, and lengthy periods of degassing are necessary to ensure no bubbles remain before measurements are taken. To tackle the problem of sediment backscatter signal contamination, a new research project is investigating how to detect and quantify bubbles present in sediment suspensions, with the aim of decomposing the backscatter signal into its sediment and bubble components. The first step in evaluating new acoustic techniques is to welcome back the bubble to the sediment tower from its long exile so it can become the focus of observations. The paper describes the recirculating suspended sediment tower and the newly introduced bubble generation and observation apparatus, which is being used to generate and observe controlled bubble populations. Bubble detection and measurement techniques are described, and initial results using a commercial acoustic backscatter profiler are presented.

Substorm onset location varies over a range of magnetic local times (MLTs) and magnetic latitudes (MLats). Different studies have shown that about 5${\%}$ of the variation in onset MLT can be explained by variations in interplanetary magnetic field orientation and seasonal variations. Both parameters introduce an azimuthal component to the magnetic field in the magnetosphere such that the projection of the onset MLT in the ionosphere is shifted. Recent studies have suggested that gradients in the ionospheric Hall conductance lead to a duskward shift of the magnetotail dynamics, which could also influence the location of substorm onset. In this paper, we quantify the dependence of the spatial variation of the onset location on the geomagnetic activity level prior to onset. We find that the dependence of onset location on prior conditions is as strong as the dependence on IMF By.

Lipids are key targets for current, proposed, and future life detection missions to both rocky and icy worlds. With the high accuracy and low limit of detection (LoD) required by many new and future instruments (sub ~ppb range), decontamination of life detection hardware, particularly components that handle or process planetary samples in situ, is necessary to prevent false positives. Lipids are a biosignature of interest as they are ubiquitous to all life as we know it, can survive in the geologic record for an order of magnitude longer than any other biomolecule (i.e. billions of years), and are able to form through both biotic and abiotic processes. Traditional NASA contamination control (CC) for life detection instruments primarily focuses on hardware fabrication in sterile cleanroom environments, killing of microbes, and flushing/mechanically removing contaminants off instrument and spacecraft components. However, recent studies suggest that standard cleaning methods are unlikely to sufficiently remove lipid contaminants to meet instrument LoD. These include NASA-approved methods for Planetary Protection (PP) (e.g., dry heat microbial reduction and vapor phase H2O2) and cleanroom decontamination methods (e.g., protective clothing, HEPA air filtration, surface cleaning with detergents/water/isopropyl alcohol, autoclave, ethylene oxide treatment). Effective laboratory standard decontamination methods (ashing at 550° C, chlorinated solvent flushes) are efficient at eliminating lipid contamination, but are often incompatible with sensitive materials required in the construction of life detection instrument components. We will present the results of a study to determine the efficiency of lipid decontamination using a “nontraditional” CC method, Electron Beam Irradiation (EBI), that would be compatible with common major instrument materials used in life detection instrumentation. Percent lipid reduction following EBI application will be compared to percent reduction following treatment with traditional NASA PP methods, using standards from four classes of lipid molecules that are proposed targets of life detection instrumentation.

A new analytical model is presented in order to better understand the depth-dependent wave-induced steady current caused by submerged aquatic canopy-oscillatory flow interaction. The analytical model takes into account the wave and canopy properties. The model is developed by determining the dominant terms in the momentum equation by means of dimensional analysis and satisfying the mass conservation. The dimensional analysis reveals that the pressure gradient (due to wave decay) is of the same order of magnitude as the drag force, wave stress and Reynolds stress terms. In addition, the balance between the pressure gradient and mass conservation induces a seaward current above the canopy, and the presence of the pressure gradient in the momentum equation contributes to intensify the skimming flow at the top of the canopy. Finally, given that the model follows a polynomial function it can be easily implemented in large scale models such as phase average models.

A document by Sushel Unninayar. Click on the document to view its contents.

We describe the quasi-periodic (QP) whistler-mode emissions found in the plasmasphere as detected by electric and magnetic instrumentation onboard the Demonstration and Science Experiments (DSX) spacecraft in medium Earth orbit. Over the course of the nearly 2-year mission, at least 45 episodes of whistler mode QP emissions were detected by the Broad Band Receiver (BBR) onboard DSX. Episodes of QP emissions were identified by discrete events having a clear unambiguous periodic nature as detected by both the electric antennae and search coil magnetic sensor in the BBR survey data at 30 second temporal resolution. Most of the QP episodes occurred in a frequency range between 1- 4 kHz, in a band previously identified by Van Allen Probes and Cluster investigators. However, episodes were also detected by DSX at higher frequencies - events in these episodes extending all the way to 15 kHz. We present our findings on these unusual high frequency events in the presentation herein. Specifically, these high frequency QP episodes tended to be observed near dawn/dusk when the spacecraft was at relatively high magnetic latitudes and on magnetic L-shells between 3-5. Another unusual feature of these episodes is that individual up-drifting events making up the episode were found to sometimes occur concurrently in time: The high frequency portion of one up-drifting ‘polliwog-shaped’ event overlapped in time with the low frequency portion of the subsequent event. This behavior of the QP emissions has not been previously emphasized and we consider how this temporal concurrence relates to the source processes.