The role of plate tectonics in the deep carbon cycle is crucial for understanding Earth’s climate, planetary life, and atmospheric CO2 over geological time; however, knowledge of carbon sources and sinks is dependent on reconstructed plate tectonic histories. Intra-oceanic subduction (i.e. subduction of an oceanic plate beneath another oceanic plate) is a recognized knowledge gap in plate tectonic reconstructions, especially within Pacific-Panthalassa, because continuous recycling of oceanic plates into the mantle leaves fewer geological traces. We examine the role of unassessed intra-oceanic subduction on paleoclimate reconstructions since the Mesozoic. We compare two global plate reconstructions: ”Tomopac” version 1, which integrates tomography and other constraints to enhance intra-oceanic subduction histories within Pacific-Panthalassa; and a widely-used model that implements less intra-oceanic subduction (Matthews et al., 2016). We model global seafloor ages, estimate total and areal subducted carbon since 200 Ma, and input subduction histories into the COPSE biogeochemical model (Lenton et al., 2021) to compare predicted global atmospheric CO2 and mean surface temperature histories. Tomopac with more intra-oceanic subduction shows a ~5% increase in global subduction zone lengths but a ~8% decrease in global subducted area and slab flux since 200 Myr. Overall, contrasted intra-oceanic subduction histories since 200 Ma alter estimates of subducted carbon by ~15-20%. Incorporating previously unassessed intra-oceanic subduction from Tomopac in COPSE reduces global mean surface temperatures up to 2°C and reduces atmospheric CO2 up to 300 ppm from 200 Ma to present, highlighting the importance of recognizing intra-oceanic subduction in modulating Earth’s long-term paleoclimate.

In aeromagnetic measurement, accurate compensation for the interference magnetic field generated by the aircraft platform due to the aircraft maneuvering in the Earth's magnetic field is an important prerequisite for the accurate indentification of the magnetic anomaly signal of the detection target. The flaws of the traditional calibration flight scheme in aeromagnetic interference compensation are firstly analyzed, and then an improved scheme is proposed, featuring smaller calibration flight areas, more simplified maneuvers, shorter flight route and less influence from the magnetometer's direction. The improved scheme can enhance the robustness of the aeromagnetic interference compensation matrix, and improve the compensation efficiency, and thus both the solved magnetic compensation coefficients and compensation effects are significantly improved. The experimental results of aeromagnetic interference compensation in an area of Inner Mongolia of China show that the average accuracy of the repeated survey lines, which are compensated by the improved scheme, can be increased by 5 nT and 3 nT, respectively, compared with the uncompensated results and the results compensated by the traditional scheme. Therefore, the effectiveness and superiority of the improved calibration flight scheme is fully proved.

The CO2 emission of human breath will not increase the CO2 of the atmosphere and raise the temperature, or so science journalists forcefully claim, because the emission is recycled by green plants, which take up CO2 to generate our food. Emission and retrieval are assumed to be in perfect balance, no CO2 is left to escape into the atmosphere. This faulty argument dominated the literature for years. A correct analysis would take all CO2 fluxes into account. It would add the simultaneous emissions, including the emission of breath (B) and subtract from this sum (S) the fluxes of all sinks (P) to obtain the overall flux of CO2 escaping into the atmosphere per year (S-P). Then the escape-flux due to breath-emission is found to be b = B (1 - P/S). Thus human breath increases the atmospheric CO2 , after all.

The Southern Ocean and coastal Antarctica are key regions for global climate. Low level mixed-phase clouds strongly control the surface radiation budget of this region but remain challenging for climate models because of the complex interactions between cloud liquid water and ice crystals. Here we examine these interactions using the Unified Model (UM) regional climate model, with the Cloud AeroSol Interacting Microphysics (CASIM) and UK Chemistry and Aerosol (UKCA) models included for interactive aerosol and cloud microphysics. We simulate case studies from the second field campaign of Clouds Aerosols Precipitation Radiation and atmospheric Composition over the Southern Ocean Phase 2 (CAPRICORN-2). Compared to these observations, we find that the UM underestimates surface aerosol concentration by up to an order of magnitude and investigate the effect of this bias on the simulated cloud microphysical and radiative properties. We find that the cloud liquid water path and surface radiative fluxes are also biased in the model, with a 32% mean underestimation of liquid water path and 76% mean overestimation of downwelling surface shortwave flux in one case study. Sensitivity tests show that the cloud liquid water bias is largely caused by deficiencies in the representation of the meteorology, and less by aerosol or cloud microphysical properties. Our results provide key insights on the modeling of cloud processes in high southern latitudes.

A document by Chris Bezu. Click on the document to view its contents.

Measurements of solar energy entering Earth are critical for comparison/validation of model simulated climate signals run in the present, for confidence in their predictions. Satellite systems detect the predicted climate trends being sought with decades of data, and so must minimize their on-orbit measurement calibration drifts, to prevent false conclusions. Reductions in Earths reflectivity would contribute to global warming by the more sunlight absorbed. New Earth reflectivity results are shown here from the Moon and Earth Radiation Budget Experiment (MERBE). As detailed in other works, this uses the constant lunar reflectivity, viewed monthly by NASA’s CERES devices, allowing MERBE to track/compensate for otherwise undetectable telescope degradation. MERBE results find Earth mean reflectivity constant compared to that of the Moon, because Arctic warming is balanced by cooling elsewhere. This physical evidence shows that the Sun does not contribute to recent global warming, confirming anthropogenic greenhouse gas increases as the likely cause.

The Mars 2020 rover will land in Jezero crater, characterize the local geology, and collect samples to be sent back to Earth. Ionizing radiation at the martian surface degrades the complex organic molecules sought by this mission, making it critical to mission success that samples be selected from recently eroded strata minimally exposed to surface radiation. Erosion on modern Mars is driven by wind. We used numerical modeling to identify sites near the rover landing area where recent aeolian erosion has likely occurred. Large eddy simulation of turbulent airflow over topography was coupled with interpretations of the surface geology to characterize wind-driven erosion across the Jezero crater delta deposit. We discuss potential sediment sources that could drive abrasion and calculate the largest grains mobilized by typical winds over the study area. Our results identify several locations likely eroded by recent winds that provide optimal sites for sample collection.

The uncertainty of climate projection is significantly contributed by warm cloud feedback, which involves a complex interplay of various mechanisms. However, it is hard to unentangle temperature’s impact on a single cloud with experiments, since the cloud dynamics always covaries with environmental thermodynamical conditions. In this study, we investigate a simulated single shallow cumulus cloud’s response to temperature using two perturbation methods, namely “uniform” and “buoyancy-fixed”, the latter of which keeps the buoyancy profile unchanged in temperature perturbation. High-resolution large eddy simulation shows that uniform warming significantly increases cloud buoyancy, reducing cloud adiabaticity. If buoyancy is fixed, warming only reduces cloud area, leaving adiabatic fraction almost unchanged. Such response can be explained by Clausius-Clapeyron effect with an idealized 1D diffusion model, showing that warming increases the cloud-environment absolute humidity difference more than the increase in cloud liquid water content, resulting in a faster loss in both cloud coverage and total liquid water solely by lateral mixing. The responses of cloud coverage and total liquid water counteract, making adiabatic fraction insensitive to temperature change. Our works shows that cloud adiabatic fraction’s response to temperature is sensitive to the perturbed structure of the boundary layer, and the cloud coverage reduction by diffusion acts as positive cloud feedback mechanism in addition to the adjustment processes of the boundary layer.

Recent space missions have identified organics, chlorinated and non-chlorinated, on Mars. Understanding the origin, current state and reactivity of this carbonaceous material is critical to efforts to detect organic signatures of possible past life on Mars. Environmental effects such as UV radiation, pressure, diagenesis, aqueous activity and presence of perchlorates have been previously been assessed using analog experiments. To this list, Fox, et al. adds and quantifies the effect of galactic cosmic rays and solar winds on organic material on the surface and in the near sub-surface of Mars. Their work, using laboratory analog materials and radiation, shows that the same organic acids, formic and oxalic acid, are produced after exposure equivalent to that over Martian history at depths of less than 5 cm, independent of mineral matrix or starting organic materials. These experiments suggest that planned sub-surface exploration using the drill on the Rosalind Franklin Rover (ExoMars) will sample organic material which has not been altered by cosmic rays, although it may have been exposed to other environmental factors such as water or salts.

Atmospheric photoelectrons are central to the production of planetary ionospheres. They are created by photoionization of the neutral planetary atmosphere by solar EUV and soft X-ray irradiance. They provide the energy to heat the thermosphere. Thermalized photoelectrons permeate magnetospheres creating polarization electric fields and plasma waves as they interact with ions to maintain charge neutrality. Energetic photoelectrons (>1 eV) have a distinctive energy spectral shape as first revealed in data from the Atmosphere Explorer satellites. Energetic photoelectrons escaping the ionosphere follow local magnetic fields illuminating the planet’s magnetic topology. Current models using state-of-the-art EUV observations accurately capture their production and transport. However, in spite of 60 years of space research the electron thermalization processes occurring below 1 eV at low altitudes in planetary thermospheres are not understood quantitatively. Results from event analysis of data from the Mars Atmosphere and Volatile Evolution (MAVEN) mission are not consistent with current models of photoelectron thermalization. The lack of quantitative understanding reflects the complexity of the physics and the lack of a large data base of simultaneous neutral, ion, and electron densities and temperatures in lower planetary thermospheres Introduction:

Flood risk across the western United States (US) has generally shown decreasing trends in recent decades. This region’s extreme streamflow is highly influenced by natural variability, which could either mask or amplify anthropogenic streamflow trends. In this study, we utilize a technique known as dynamical adjustment to assess historical (1970-2020) annual maximum 1-day streamflow (Qx1d) from unregulated basins across the western US with and without the impact of natural variability. After removing natural variability, the fraction of basins with a positive (>5%) trend in Qx1d shifts from 27% to 61%. Basins with significantly increasing (decreasing) Qx1d trends after dynamical adjustment exhibit weak (strong) drying, and furthermore are associated with intensifying precipitation extremes and/or large decreases in snowpack. Increasing flood risk will likely emerge for such basins as the current phase of natural decadal variability shifts, and anthropogenic signals continue to intensify.

To assist water managers in south-central Oklahoma prepare for future drought, reliable place-based drought forecasts are produced. Past, present, and future-forecasted climate indices (Multivariate ENSO Index, Pacific Decadal Oscillation index, and Atlantic Multidecadal Oscillation index) and past and present Palmer Drought Severity Index (PDSI) are employed as predictor variables to forecast PDSI using a multivariate regression technique. PDSI is forecasted 18 months in advance with sufficient skill to provide water managers early warning of drought. Using a training dataset from January 1901 to November 2021, a second-order model equation that contains, without any restriction, all the predictors and interaction terms is built to predict drought intensity. Significant predictors are selected through stepwise regression, with cross-validation producing the simplest restricted model that describes the data well. PDSI values are predicted using 1000 fitted restricted models produced from bootstrapping, then averaged monthly. The technique found the best-fitting model and estimated the model coefficients that minimized the sum of squared deviations between the fitted model and the predictor variables. The adjusted R-squared value of the restricted model is large enough to explain the strength of the model, and relatively low values of error measures point to good predictive ability of the model. Although the model slightly overestimates the PDSI forecast maxima and minima, it necessarily captures the timing of the periods of severe to exceptional drought.

The morphology of the auroral oval is an important geophysical parameter that can be used to uncover the solar wind-geomagnetic field interaction process and the intrinsic mechanism. However, it is still a challenging task to automatically obtain auroral poleward and equatorward boundaries completely and accurately. In this paper, a new model based on the deep feature and dual level set method is proposed to extract the auroral oval boundaries in the images acquired by the Ultraviolet Imager (UVI) onboard the Polar spacecraft. With the deep feature extracted by the convolutional neural network (CNN), the corresponding deep feature energy functional is constructed and incorporated into the variational segmentation framework. The dual level set method is implemented to extract the accurate poleward and equatorward boundaries with the gradient descent flow. The experimental results on the test data set demonstrate that this model can extract complete auroral oval contours that are consistent well with expert annotations and owns higher accuracy compared with the previously proposed methods. Besides, the comparison between the extracted auroral boundaries and the precipitating boundaries determined by Defense Meteorological Satellite Program (DMSP) SSJ precipitating particle data validates that the proposed method is trustworthy to capture the global morphology of the auroral ovals.

Ions in the F region ionosphere at 150-400 km altitude consist mainly of molecular NO+ and O2+, and atomic O+. Incoherent scatter (IS) radars are sensitive to the molecular-to-atomic ion density ratio, but its effect to the observed incoherent scatter spectra is almost identical with that of the ion temperature. It is thus very difficult to fit both the ion temperature and the fraction of O+ ions to the observed spectra. In this paper, we introduce a novel combination of Bayesian filtering, smoothness priors, and chemistry modeling to solve for F1 region O+ ion fraction from EISCAT Svalbard IS radar (75.43° corrected geomagnetic latitude) data during the international polar year (IPY) 2007-2008. We find that the fraction of O+ ions in the F1 region ionosphere is controlled by ion temperature and electron production. The median value of the molecular-to-atomic ion transition altitude during IPY varies from 187 km at 16-17 MLT to 208 km at 04-05 MLT. The ion temperature has maxima at 05-06 MLT and 15-16 MLT, but the transition altitude does not follow the ion temperature, because photoionization lowers the transition altitude. A daytime transition altitude maximum is observed in winter, when lack of photoionization leads to very low daytime electron densities. Both ion temperature and the molecular-to-atomic ion transition altitude correlate with the Polar Cap North geomagnetic index. The annual medians of the fitted transition altitudes are 14-32 km lower than those predicted by the International Reference Ionosphere.

Flux transfer events (FTEs) are a type of magnetospheric phenomena that exhibit distinctive observational signatures from the in-situ spacecraft measurements across the Earth’s magnetopause. They are generally believed to possess a magnetic field configuration of a magnetic flux rope and formed through magnetic reconnection at the dayside magnetopause, sometimes accompanied with enhanced plasma convection in the ionosphere. We examine two FTE events under the condition of southward interplanetary magnetic field (IMF) with a dawn-dusk component at the magnetopause by applying the Grad-Shafranov (GS) reconstruction method to the in-situ measurements by the Magnetospheric Multiscale (MMS) spacecraft to derive the magnetic flux contents associated with the FTE flux ropes. In particular, given a cylindrical magnetic flux rope configuration derived from the GS reconstruction, the magnetic flux content can be characterized by both the toroidal (axial) and poloidal fluxes. We then estimate the amount of magnetic flux (i.e., the reconnection flux) encompassed by the area “opened” in the ionosphere, based on the ground-based Super Dual Auroral Radar Network (SuperDARN) observations. We find that for event 1, the FTE flux rope is oriented in the approximate dawn-dusk direction, and the amount of its poloidal magnetic flux agrees with the corresponding reconnection flux. For event 2, the agreement among the estimates of the magnetic fluxes is uncertain. We provide a detailed description about our interpretation for the topological features of the FTE flux ropes, based on a formation scenario of sequential magnetic field reconnection between adjacent field lines, consistent with our results.

Before dawn on the dustiest regions of Mars, surfaces measured at or below ∼ 148 K are common. Thermodynamics principles indicate that these terrains must be associated with the presence of CO2 frost, yet visible wavelength imagery does not display any ice signature. We interpret this systematic absence as an indication of CO2 crystal growth within the surficial regolith, not on top of it, forming hard-to-distinguish intimate mixtures of frost and dust, i.e., dirty frost. This particular ice/regolith relationship unique to the low thermal inertia regions is enabled by the large difference in size between individual dust grains and the peak thermal emission wavelength of any material nearing 148 K (1-2 μm vs. 18 μm), allowing radiative loss (and therefore ice formation) to occur deep within the pores of the ground, below several layers of grains. After sunrise, sublimation-driven winds promoted by direct insolation and conduction create an upward drag within the surficial regolith that can be comparable in strength to gravity and friction forces combined. This drag displaces individual grains, possibly preventing their agglomeration, induration, and compaction, and can potentially initiate or sustain downslope mass movement such as slope streaks. If confirmed, this hypothesis introduces a new form of CO2-driven geomorphological activity occurring near the equator on Mars and explains how large units of mobile dust are currently maintained at the surface in an otherwise soil-encrusting world.

The Cassini mission yielded a treasure trove of information on Saturn's largest moon Titan. With many flybys of this complex moon Cassini revealed many aspects of Titan's upper atmosphere and interaction with Saturn's magnetosphere. In many ways Cassini revealed that this moon is unique in that it sustains a dense atmosphere and ionosphere even without the protection of an internal magnetic field. Key to the understanding of this ionosphere is understanding the ion dynamics of Titan's upper atmosphere, namely how these ions are created and lost either to the lower atmosphere where they fall and can contribute to the creation of the complex hydrocarbons seen at the surface or are carried away with Saturn's rapidly flowing magnetospheric particles. Here we present novel measurements of the velocities of many ion species in Titan's upper atmosphere. We show that multiple processes must be responsible for the acceleration of these ions as there is evidence for both mass dependent and independent acceleration. We also show that heavy, relatively complex molecular ions are accelerated and carried into the magnetospheric flow. These ions could contribute to mass loading processes and possibly additional changes in the magnetosphere when Titan resides in Saturn's magnetotail.

This paper presents a methodology to assess the influence of the correlation-covariance structure of measurement errors in online monitoring over the propagation of uncertainties, applied to wet-weather environmental indicators in Sustainable Urban Drainage Systems (SUDS). The effect of autocorrelated and heteroscedastic errors in measured time-series over the estimated Probability Density Function (PDF) of different environmental indicators is analyzed for a wide variety of possible error structures in the data. For this purpose, multiple correlation-covariance structures are randomly generated from exploring the parametric space of a Linear Exponent Autoregressive (LEAR) model, employing a Bayesian-based Markov Chain Monte Carlo sampling technique. Significant differences tests are proposed to identify the most correlated parameters of the correlation-covariance error model with statistics of the environmental indicators PDFs. The methodology is applied to Total Suspended Solids (TSS) and Chemical Oxygen Demand (COD) time-series recorded during 13 rainfall events at the inlet and outlet of a SUDS train (stormwater settling tank - horizontal constructed wetland). For this case, results showed that the total error in the estimation of the analyzed environmental indicators is mostly explained by standard uncertainties (flattening of the PDFs) rather than bias contributions (displacement of the PDFs). The correlation-covariance model parameters related to the temporal delimitation of hydrographs/pollutographs and the intensity of the autocorrelation showed to have the strongest influence in the propagation of measurement errors (flattening/displacement of the PDFs).