We investigate the relationship between NO infrared radiation and x-ray radiation at different local time (LT) and latitudes of NO average fluxes. The NO volume emission rates obtained by SABER instrument on board TIMED satellite and x-ray fluxes on long (0.1-0.8 nm) and short (0.05-0.4) channels measured by GOES 12 satellite were used. NO rates were vertically integrated to obtain fluxes, which are then separated into day (8

The Community Multiscale Air Quality (CMAQ) model is a state-of-the-science chemical transport model (CTM) capable of simulating the emission, transport and fate of numerous air pollutants. Similarly, the Weather Research and Forecasting (WRF) model is a state-of-the-science meteorological model capable of simulating meteorology at many scales (e.g. global to urban). The coupled WRF-CMAQ system integrates these two models in a “two-way” configuration which allows feedback effects between the chemical (e.g. aerosols) and physical (e.g. solar radiation) states of the atmosphere and more frequent communication between the CTM and meteorological model than is typically done in uncoupled WRF-CMAQ simulations. In this study we apply the various cumulus parameterization (CP) options available in WRF at horizontal grid spacings ranging from regional scale (i.e. 12-km) to urban scale (i.e. 4 and 1 km), focused on the July 2011 DISCOVER-AQ campaign that took place over the Baltimore-Washington D.C region. Of particular interest is the evaluation of the WRF simulated clouds, as analysis of previous WRF-CMAQ simulations using a “standard” 12-km configuration for the model suggest that WRF has difficulty predicting clouds (particularly fair-weather clouds), with decreasing skill at finer horizontal grid spacings. Here we will examine the impact that the WRF CP options have on cloud predictions, using available satellite data to evaluate model the performance. We then examine how changes in the WRF simulated clouds affect CMAQ predictions of ozone and PM2.5 at the various scales.

Arid and semiarid regions account for ~ 40% of the world’s land area. Rivers and lakes in these regions provide sparse, but valuable, water resources for the fragile environments; and play a vital role in the development and sustainability of local societies. During the late 1980s, the climate of arid and semiarid northwest China dramatically changed from “warm-dry” to “warm-wet”. Understanding how these environmental changes and anthropogenic activities affect water quantity and quality is critically important for protecting the aquatic ecosystem and determining the best use of freshwater resources. Lake Bosten is the largest inland freshwater lake in NW China and has experienced inter-conversion processes between freshwater and brackish status. Herein, we explored the long-term water level and salinity trends in Lake Bosten from 1958 to 2019. During the past 62 years, Lake Bosten’s water level and salinity exhibited “W” and “M” patterns. Partial least squares path modeling (PLS-PM) suggested that the decreasing water level and salinization during 1958–1986 were mainly caused by anthropogenic activities, while the variations in water level and salinity during 1987–2019 were mainly affected by climate change. The transformation of anthropogenic activities and climate change is beneficial for sustainable freshwater management in Lake Bosten Catchment. Our findings highlight the benefit of monitoring aquatic environmental changes in arid and semi-arid regions over the long-term for the purpose of fostering a balance between socioeconomic development and ecological protection of the lake environment.

Methane is the second most important anthropogenic greenhouse gas causing warming after carbon dioxide, and the emission reductions potentials are known to be limited due to the difficulty of abating agricultural methane. We explore in this study the emerging option of atmospheric methane removal (MR) that could complement carbon dioxide removal (CDR) in mitigation pathways. MR is technologically very challenging and potentially very expensive, so the main question is at which cost per ton of methane removed is MR more cost effective than CDR. To address this question, we use an intertemporal optimization climate-GHG-energy model to evaluate the MR cost and removal potential thresholds that would allow us to meet a given climate target with the same or a lower abatement cost and allowing for equal or higher gross CO2 emissions than if CDR through BECCS were an option. We also compare the effects of MR and CDR on the cost-effective mitigation pathways achieving four different climate targets. Using the ACC2-GET integrated carbon cycle, atmospheric chemistry, climate and energy system model, we consider a generic MR technology characterized by a given unit cost and a maximal removal potential. We show that to totally replace bioenergy based CDR with MR, the MR potential should reach at least 180 to 320 MtCH4 per year, i.e., between 50% and 90% of current anthropogenic methane emissions, with maximum unit cost between 10,000 and 34,000 $/tCH4, depending on the climate target. Finally, we found that replacing CDR by MR reshapes the intergenerational distribution of climate mitigation efforts by delaying further the mitigation burden.

Key Points: • The recurrence time of large earthquakes (M ï¿¿ 8.1) is 1200 years in the Long-men Shan collision zone. • MMI ï¿¿ ï¿¿½ (M ï¿¿ 5.9, R min ï¿¿ 10 km) is the lower-bound conditions for triggering the deformation in the Lixian lacustrine sediments. • The Maoxian-Wenchuan fault is the main fault that triggered the deformation in Lixian lacustrine sediments. Abstract The thrust collision zone with a low slip rate along the plate boundary is the main stress accumulation area and prone to occur more destructive earthquakes with a longer recurrence interval. Such region is often classified as low seismic risk if lack of continuous records of large earthquakes, such as the eastern Ti-betan Plateau before the 2008 M w 7.9 Wenchuan earthquake. Here, we provide a continuous seismic record in the Longmen Shan thrust fault zone spanning 13000 years based on detailed investigation of the soft-sediment deformation structures and seismites in the Lixian lacustrine sequence. The recurrence time of large earthquakes (M ï¿¿ 8.1) is 1200 years, which is significantly shorter than the previous estimate of 2000-6000 years. The Maoxian-Wenchuan fault is the main fault that triggered the deformation in the Lixian lacustrine sediments. In addition, the frequency of earthquake recurrence in the warm period is more frequent than that in the cold period, which should arouse our attention on the seismic study in the tectonically active regions. Plain Language Summary The Longmen Shan fault zone was evaluated as a low seismic risks area before 2008 because of complete failure of trenching paleoseismic research in the eastern Tibetan Plateau, which led to the severe casualties and property losses caused by the 2008 Wenchuan Ms 8.0 earthquake. Therefore, it is urgent to explore new research methods to reveal the paleoseismic records in the eastern 1 Tibetan Plateau. Continuous lacustrine deposition is a good carrier for revealing tectonic events. The soft-sediment deformation and seismites recorded in lacustrine sediments can be good indicators of paleoseismic event. Here, we redefined the soft-sediment deformation and seismic records of the Lixian lacus-trine sediments in the Longmen Shan fault zone, and discussed the recurrence time and recurrence model of regional earthquakes by linking them with earthquake intensity. We obtain that much shorter recurrence interval (1400 years) of large earthquakes (M ï¿¿ 8.1) are recorded in the Lixian lacustrine sediments compared with earlier studies (2000-6000 years), and the large earthquake have a random earthquake recurrence model of plate boundaries. These results are very important for reassessing the seismic risk of the Longmen Shan fault zone in the eastern Tibetan Plateau.

Global Earth system model simulations of ocean carbon export flux are commonly interpreted only at a fixed depth horizon of 100-m, despite the fact that the maximum annual mixed layer depth (MLDmax) is a more appropriate depth horizon to evaluate export-driven carbon sequestration. We compare particulate organic carbon (POC) flux and export efficiency (e-ratio) evaluated at both the MLDmax and 100-m depth horizons, simulated for the 21st century (2005-2100) under the RCP8.5 climate change scenario with the Biogeochemical Elemental Cycle model embedded in the Community Earth System Model (CESM1-BEC). These two depth horizon choices produce differing baseline global rates and spatial patterns of POC flux and e-ratio, with the greatest discrepancies found in regions with deep winter mixing. Over the 21st century, enhanced stratification reduces the depth of MLDmax, with the most pronounced reductions in regions that currently experience the deepest winter mixing. Simulated global mean decreases in POC flux and in e-ratio over the 21st century are similar for both depth horizons (8-9% for POC flux and 4-6% for e-ratio), yet the spatial patterns of change are quite different. The model simulates less pronounced decreases and even increases in POC flux and e-ratio in deep winter mixing regions when evaluated at MLDmax, since enhanced stratification over the 21st century shoals the depth of this horizon. The differing spatial patterns of change across these two depth horizons demonstrate the importance of including multiple export depth horizons in observational and modeling efforts to monitor and predict potential future changes to export.

Primary productivity of an aquatic system like Arabian Sea is broadly determined by the concentration of Chlorophyll-a (Chl-a/Ca) pigment. The present study is essaying to validate the Chl-a data set of prominent ocean color sensors (OC3M - MODIS, OC-OCM2, and OC3V-VIIRS) with sea truth data, collected from 204 stations for three year period (2015-2017). The in-situ concentrations of Chl-a depicts the geographic region under the mesotrophic and eutrophic spans ((0.1>Ca>1.0 mg m-3). The ratio of CaOCM2/CaIn-situ is 0.97±0.27 mg m-3 (n=199), in unsimilarity with CaVISSR/CaIn-situ is 1.75±0.79 mg m-3 (n=170) and CaMODIS/CaIn-situ is 2.53±1.42 mg m-3 (n=158). The regression analysis proclaims a moderate significant relationship for MODIS (r2 = 0.36; p<0.001), followed OCM2 (r2 = 0.32; p<0.001) and VISSR (r2 = 0.19; p<0.001) with evident overestimation (MODIS and VIRRS) and in tune (OCM2) with the satellite-derived datasets. The global ocean color missions aimed to set RMSE error at 0.35, the OCM2 shown the lowest RMSE as 0.13, which is relatively lower than the reference error limit. In overall performance among three algorithms, the OCM2 will provide a better estimation of Chl-a with a prediction of 32% accuracy and 34.37 % of bias. The log bias values for MODIS (0.35) and VIIRS (0.20) algorithms indicating the overestimation of Chl-a with in-situ concentrations, but the OCM2 algorithm is suitable in the region with a negligible bias of -0.03. The biogeochemical processes and ecosystem characteristics are dynamic from region to region, as yet in its urgent need to validate global and formulate regionally tuned algorithms periodically.

The most general models for glacial hydrologic conduits include an energy equation, wherein a heat transfer coefficient controls the rate at which heat generated by mechanical energy dissipation is transferred to conduit walls, producing melt. Previous models employ heat transfer coefficients derived for engineering heat transfer problems, where heat is transferred between the walls of a conduit and a flowing fluid that enters the duct at a temperature different from the wall temperature. These heat transfer coefficients may not be appropriate for glacial hydrologic conduits in temperate ice, where the flowing fluid (water) and conduit walls (ice) are at almost the same temperature, and the heat generated by mechanical energy dissipation within the flow is transferred to the walls to produce melt. We revisit the energy transport equations that provide a basis for the derivation of heat transfer coefficients and highlight the distinctions between the heated walls and dissipated energy heat transfer cases. We present computational results for both cases across a range of Reynolds numbers in circular conduit and sheet geometries. For the heated walls case, our results are consistent with the widely used Dittus-Boelter heat transfer correlation, which has been used in previous glacial conduit models. We show that the heat transfer coefficient for transfer of heat generated by mechanical energy dissipation to conduit walls is smaller than that calculated using the Dittus-Boelter correlation by approximately a factor of 2.

The Cabled Observatory Vent Imaging Sonar (COVIS) was installed on the Ocean Observatories Initiative’s Cabled Array observatory at ASHES hydrothermal vent field on Axial Seamount in July 2018. The acoustic backscatter data recorded by COVIS, in conjunction with in-situ temperature measurements, are used to investigate the temporal and spatial variations of hydrothermal discharge within ASHES. Specifically, sonar data processing generates three-dimensional backscatter images of the buoyant plumes above major sulfide structures and two-dimensional maps of diffuse hydrothermal sources within COVIS’s field-of-view. The backscatter images show drastic changes of plume appearance and behavior that potentially reflect episodic variabilities of vent fluid composition and/or outflow fluxes. The diffuse-flow maps show that the areal extent of hydrothermal discharge on the seafloor varies significantly with time, which is largely driven by bottom currents and potentially tidal loading. These findings demonstrate COVIS’s ability to quantitatively monitor hydrothermal discharge with sufficient spatial and temporal coverage to provide the research community with key observational data for studying the linkage of hydrothermal activity with oceanic and geological processes during the dynamic period leading up to the next eruption of Axial Seamount.

Plasmas in Earth’s outer magnetosphere, magnetosheath, and solar wind are essentially collisionless. This means particle distributions are not typically in thermodynamic equilibrium and deviate significantly from Maxwellian distributions. The deviations of these distributions can be further enhanced by plasma processes, such as shocks, turbulence, and magnetic reconnection. Such distributions can be unstable to a wide variety of kinetic plasma instabilities, which in turn modify the electron distributions. In this paper the deviations of the observed electron distributions from a bi-Maxwellian distribution function is calculated and quantified using data from the Magnetospheric Multiscale (MMS) spacecraft. A statistical study from tens of millions of electron distributions shows that the primary source of the observed non-Maxwellianity are electron distributions consisting of distinct hot and cold components in Earth’s low-density magnetosphere. This results in large non-Maxwellianities in at low densities. However, after performing a stastical study we find regions where large non-Maxwellianities are observed for a given density. Highly non-Maxwellian distributions are routinely found are Earth’s bowshock, in Earth’s outer magnetosphere, and in the electron diffusion regions of magnetic reconnection. Enhanced non-Maxwellianities are observed in the turbulent magnetosheath, but are intermittent and are not correlated with local processes. The causes of enhanced non-Maxwellianities are investigated.

The 2022 Menyuan earthquake occurred in the Qilian-Haiyuan fault system in northeastern Tibet. To investigate the reason behind this earthquake and the seismic hazards of the Tianzhu Seismic Gap, we demonstrated the spatiotemporal stress variation on the fault system before and after 2022 through numerical modelling. We found that the 2022 earthquake was delayed due to a stress shadow caused by historical earthquakes. This stress shadow also covers the middle of the Tianzhu Seismic Gap and prohibits its seismic activities to some extent. Acting as a stress barrier to prevent the Tianzhu Seismic Gap rupturing in one event, this stress shadow may decrease the possibility of generating a future earthquake of magnitude more than Mw7.7 in this gap. The east portion of the Tianzhu Seismic Gap was stress loaded, indicating its increased seismic hazards. Attention should be paid to the hazards prevention in the eastern portion of the gap.

Knowledge of snow/firn density is important for deriving ice sheet mass change from satellite altimetry and for surface mass balance modeling. However, snow/firn densities are largely unknown over the Greenland ice sheet (GrIS) away from isolated direct measurements in boreholes. Density assumptions are widely used when converting volume change from satellite altimetry into mass change, which could introduce errors. Here we extract the inter-annual anomalies of mass change from Gravity Recovery And Climate Experiment (GRACE) data and the refined ice elevation change through the repeat-track analysis of Environmental Satellite (Envisat) altimetry data retrieved using both the ICE1 and ICE2 waveform retracking algorithms. By combining these two types of inter-annual anomalies (GRACE+ICE1 and GRACE+ICE2), we investigate the inter-annually changing snow/firn density estimates over the GrIS during the 2003–2009 period. Our results demonstrate that satellite-derived density is relatively greater over Western GrIS, with magnitude falling between 300 “kg” ⁄“m” ^“3” and 917 “kg” ⁄“m” ^“3” occupying more than 71% of the GrIS. At the regional scale, GRACE+ICE1 derived density agrees well with that from density profiles of 9 ice cores at Summit Station, Central GrIS, with relative errors less than 5%. Satellite-derived densities are further compared with that from 110 ice cores mostly along the central ice divide. The percentage of GRACE+ICE1 derived densities with relative errors less than 20% exceeds 84%, as opposed to 41% for GRACE+ICE2. Satellite-derived densities could possibly underestimate the inter-annually varying snow/firn density over Southern GrIS. This study may provide constraints on the currently applied density assumptions for the GrIS.

We investigate the 3-D lithospheric thermal and rheological structures beneath Northeast China using detailed P- and S-wave velocity models following mineral physics as well as geothermal methods. Small-scale temperature changes and thermal lithosphere thickness variations between different tectonic blocks are revealed. Our results show that strong lateral heterogeneities exist in the lithospheric thermal structure and rheological structure on both sides of the North-South Gravity Lineament (NSGL). The Changbai volcanic area and the central part of the Songliao Basin in the eastern side of the NSGL exhibit higher temperatures, thinner thermal lithosphere and lower rheological strength, which are closely associated with the western Pacific plate subduction under the Eurasian continent, resulting in upwelling of wet and hot asthenospheric material above the stagnant Pacific slab in the mantle transition zone. The thermo-chemical erosion of the upwelling asthenospheric material may induce delamination of partial lithosphere under the Songliao Basin. In addition, the Songliao Basin edge is characterized by lower temperature, thicker thermal lithosphere and higher rheological strength, which may indicate a relatively stable lithosphere. The Halaha and Abaga volcanic areas in the western side of the NSGL exhibit higher temperature, thinner thermal lithosphere and lower rheological strength, which could be caused by small-scale upwelling of hot asthenospheric material associated with delamination of partial lithosphere beneath the Songliao Basin.

Based on graphical processing unit acceleration, a new method of finite-difference time-domain scheme is proposed to simulate the interaction between electromagnetic waves and magnetized plasma in two-dimensional conditions. In this study, transversely electric and transversely magnetic are computed in time to avoid matrix operations involving Lorentz equations of motion. Compared to Young’s method, the new method reduces addition and multiplication by about 63% and 66%, respectively. The simulation results of ionospheric wave propagation show that the new method agrees well with Young’s method and the calculation speed is improved significantly.

A document by Kenza Khomsi. Click on the document to view its contents.

Electric vehicle (EV) adoption promises potential air pollutant and greenhouse gas (GHG) reduction co-benefits. As such, China has aggressively incentivized EV adoption, however much remains unknown with regard to EVs’ mitigation potential, including optimal vehicle type prioritization, power generation contingencies, effects of Clean Air regulations, and the ability of EVs to reduce acute impacts of extreme air quality events. Here, we present a suite of scenarios with a chemistry-climate model that assess the potential co-benefits of EVs during an extreme winter air quality event. We find that regardless of power generation source, heavy-duty vehicle (HDV) electrification consistently improves air quality in terms of NO2 and fine particulate matter (PM2.5), potentially avoiding 562 deaths due to acute pollutant exposure during the infamous January 2013 pollution episode (~1% of total premature mortality). However, HDV electrification does not reduce GHG emissions without enhanced emission-free electricity generation. In contrast, due to differing emission profiles, light-duty vehicle (LDV) electrification in China consistently reduces GHG emissions (~2 Mt CO2), but results in fewer air quality and human health improvements (145 avoided deaths). The calculated economic impacts for human health endpoints and CO2 reductions for LDV electrification are nearly double those of HDV electrification in present-day (155M vs. 87M US$), but are within ~25% when enhanced emission-free generation is used to power them. Overall we find only a modest benefit for EVs to ameliorate severe wintertime pollution events, and that continued emission reductions in the power generation sector will have the greatest human health and economic benefits.

Semi-open hydrous pyrolysis experiments on coal-measure source rocks in the Xihu Sag were conducted to investigate the carbon isotope evolution of kerogen, bitumen, generated expelled oil, and gases with increasing thermal maturity. Seven experiments corresponding were conducted at 335 °C-575 °C, while other experimental factors, such as the heating time and rate, lithostatic and hydrodynamic pressures, and columnar original samples were kept the same. The results showed that the simulated temperatures were positive for the measured vitrinite reflectance (Ro), with a correlation coefficient (R2) of 0.9861. With increasing Ro, lower maturity, maturity, higher maturity, and post-maturity stages occurred at simulated temperatures (Ts) of 335–360 °C, 360–400 °C, 400–480 °C, and 480–575 °C, respectively. Moreover, the carbon isotopes of kerogen, bitumen, expelled oil, and gases were associated with an increased Ro. Ignoring the intermediate reaction process, the thermal evolution process can be summarized as kerogen0 (original) + bitumen0 (original) → kerogenr (residual kerogen) + expelled oil (generated) + bitumenn+r (generated + residual) + C2+ (generated + residual) + CH4 (generated). Among these, bitumen, expelled oil, and C2-5 acted as reactants and products, whereas kerogen and methane were the reactants and products, respectively. Thus, the reaction and production mechanisms of carbon isotopes can be obtained based on their changing degree and yields in kerogen, bitumen, expelled oil, and gases. Furthermore, combining the analysis of geochemical characteristics of the Pinghu Formation coal-oil-type gas in actual strata with these pyrolysis experiments, it was identified that this area also had substantial development potential.

Extreme events will become more common due to global change, requiring enhanced monitoring and pushing conventional observation networks to their limits. This encourages us to combine all the possible sources of information to obtain a complete picture of extreme events and their evolution. This commentary builds on an example of the July 2021 catastrophic floods that hit northwest Europe, for which the use of seismometer and gravimeter captures complementary data and brings a new understanding of the event and its dynamics. A sudden increase in seismic noise coincides with the testimony reporting on a “tsunami” downstream of the geophysical station. Concurrently, the gravimeter showed increasing saturation of the weathered zone, showing less and less water accumulation and increasing runoff. When rain re-intensified after a 3-hour break, the subsoil’s saturation state induced an accelerated runoff increase, as revealed by the river flow, in a much stronger way than during the rainy episodes just before. We show that the gravimeter detected the saturation of the catchment subsoil and soil in real-time. When the rain re-intensified, this saturation resulted in a sudden, devastating and deadly flood. Our study opens up the possibility of integrating real-time gravity in early warning systems for such events.