River flows change on timescales ranging from minutes to millennia. These variations influence fundamental functions of ecosystems, including biogeochemical fluxes, aquatic habitat, and human society. Efforts to describe temporal variation in river flow—i.e., flow regime—have resulted in hundreds of unique descriptors, complicating interpretation and identification of global drivers of flow dynamics. Here, we used a cross-disciplinary analytical approach to investigate two related questions: 1. Is there a low-dimensional structure that can be used to simplify descriptions of streamflow regime? 2. What catchment characteristics are most associated with that structure? Using a global database of daily river discharge from 1988-2016 for 3,120 stations, we calculated 189 traditional flow metrics, which we compared to the results of a wavelet analysis. Both quantification techniques independently revealed that streamflow data contain substantial low-dimensional structure that correlates closely with a small number of catchment characteristics. This structure provides a framework for understanding fundamental controls of river flow variability across multiple timescales. Climate was the most important variable across all timescales, especially those lasting several weeks, and likely contributes as much as dams in controlling flow regime. Catchment area was critical for timescales lasting several days, as was human impact for timescales lasting several years. In addition, both methods suggested that streamflow data also contain high-dimensional structure that is harder to predict from a small number of catchment characteristics (i.e. is dependent on land use, soil structure, etc.), and which accounts for the difficulty of producing simple hydrological models that generalize well.

The total meridional heat transport (MHT) is relatively stable across different climates. Nevertheless, the strength of individual processes contributing to the total transport are not stable. Here we investigate the MHT and its main components especially in the atmosphere, in five coupled climate model simulations from the Deep-Time Model Intercomparison Project (DeepMIP). These simulations target the Early Eocene Climatic Optimum (EECO), a geological time period with high CO2 concentrations, analogous to the upper range of end-of-century CO2 projections. Preindustrial and early Eocene simulations at a range of CO2 levels (1x, 3x and 6x preindustrial values) are used to quantify the MHT changes in response to both CO2 and non-CO2 related forcings. We found that atmospheric poleward heat transport increases with CO2, while the effect of non-CO2 boundary conditions (e.g., paleogeography, land ice, vegetation) is causing more poleward atmospheric heat transport on the Northern and less on the Southern Hemisphere. The changes in paleogeography increase the heat transport via transient eddies at the mid-latitudes in the Eocene. The Hadley cells have an asymmetric response to both the CO2 and non-CO2 constraints. The poleward latent heat transport of monsoon systems increases with rising CO2 concentrations, but this effect is offset by the Eocene topography. Our results show that the changes in the monsoon systems’ latent heat transport is a robust feature of CO2 warming, which is in line with the currently observed precipitation increase of present day monsoon systems.

Climate change has altered the frequency, intensity, and timing of mean and extreme precipitation events. Extreme precipitation has caused tremendous socio-economic losses and displays strong regional variability. Although many previous studies have addressed daily extreme precipitation, hourly extreme rainfall still needs to be thoroughly investigated. In this study, we investigated the trends, spatio-temporal variability, and long-term variations in mean and extreme precipitation over South Korea using daily and hourly observational data. During the past 50 years (1973–2022), there has been a notable escalation in maximum hourly precipitation, although the boreal summer mean precipitation has increased only marginally. Regionally, an increase in mean and extreme rainfall occurred in the northern part of the central region. Moreover, increased intensity and frequency of extreme precipitation have contributed more to the total summer precipitation in recent years. Our findings provide scientific insights into the progression of extreme summer precipitation events in South Korea.

The development of strawberry (Fragaria × ananassa) cultivars resistant to Phytophthora crown rot (PhCR), a devastating disease caused by the soil-borne pathogen Phytophthora cactorum, has been challenging, partly because resistance phenotypes are quantitative and only moderately heritable. To develop deeper insights into the genetics of resistance and build the foundation for applying genomic selection, a genetically diverse training population was screened for resistance to California isolates of the pathogen. Here we show that genetic gains in breeding for resistance to PhCR have been negligible (3% of the cultivars tested were highly resistant and none surpassed early twentieth century cultivars). Narrow-sense heritability for PhCR resistance ranged from 0.35-0.57. Using multivariate GWAS, we identified a large-effect locus (predicted to be RPc2) that appears to be ubiquitous, slowed symptom development, explained 43.6-51.6% of the genetic variance, was necessary but not sufficient for resistance, and was strongly associated with calcium channel and other genes with known plant defense functions. The addition of underutilized gene bank resources to our training population doubled additive genetic variance, increased the accuracy of genomic selection, and enabled the discovery of individuals carrying favorable alleles that are either rare or not present in modern cultivars. The incorporation of an RPc2-associated SNP as a fixed effect increased genomic prediction accuracy from 0.40 to 0.55. Finally, we show that parent selection using genomic-estimated breeding values, genetic variances, and cross-usefulness holds promise for enhancing resistance to PhCR in strawberry.

Soil erosion is impacted by climate and land use changes which need to be quantified to assess future risks and to design efficient soil conservation measures. The Coupled Model Intercomparison Project Phase 5 (CMIP5) simulations have provided the basis for most such assessments and yet are being gradually superseded by more recent simulations from Phase 6 (CMIP6). The High-Resolution Model Intercomparison Project (HighResMIP) experiment in CMIP6 adds value over the downscaled CMIP5 simulations by improving process representation in the global climate system. Our study investigates and compares high-resolution model simulations from CMIP6 against CMIP5. Model evaluation for the reference period (1986–2005) indicates that the CMIP6 model outperforms the regional climate models (RCM) from CMIP5 for better circulation simulations, but both overestimate soil erosion in China. The average projected soil erosion increases by 27.85 from CMIP5 and 20.03 t·hm-2·a-1 from the CMIP6 model with remarkable geographical heterogeneity. Soil erosion is projected to decrease in black soil regions, purple soil regions, and karst regions from CMIP6 results, which is opposite to the increasing trend found in those regions from CMIP5. Land use and climatic changes contributed 51.68% and -5.92% respectively from CMIP5 simulations while 35.74% and -13.77% from CMIP6 to the increased soil erosion rate. The negative contribution of land use change is gradually intensified with the CMIP6 model representing finer-scale processes of converting land-use type into cropland, pasture, and urban land. Overall, the CMIP6 projections provide a less severe soil erosion situation while addressing the need to pursue soil conservation more.

Advances in technology have increased adoption of high-throughput phenotyping (HTP) methodologies, potentially replacing laborious and time-consuming measurements and data recording. One promising HTP tool for fine-featured and small-sized characteristics are 3-dimensional (3-D) scanning and imaging systems, but the utility of present 2-D technology has not been fully explored for this purpose. The objective of this work was to develop 2-D photogrammetric and 3-D topometric imaging methods for HTP of spike characteristics in perennial ryegrass (Lolium perenne L.) with special attention to traits that might be associated with seed retention. These HTP imaging systems were compared with direct data capture by hand in spikes of 21 diverse global accessions of perennial ryegrass. The Fiji (ImageJ) open source imaging software was used for photogrammetric analysis of spike structure including spike length, spikelet number, internode length and 2-D curvature of the spike. The optical sensor Artec Space Spider 3-D scanner was used to generate dense 3-D point clouds to measure spike length, spikelet number, internode length, spikelet length, spikelet angle, and 3-D curvature of the spike. Both methods were found to accurately characterize the subject, the 3-D method was slower than 2-D but was more (P ≤ 0.01) precise than 2-D image analysis with a linear measurement deviation of only 0.17%. Fiji was effectively used for post-processing image analysis and the Space Spider can be used directly in the field to support HTP data collection. This non-destructive field measurement system facilitates HTP in perennial ryegrass spikes and likely in other applications.

MarsWRF, the general circulation model of Mars, is one of the most commonly used models to study the dust cycle in the Martian atmosphere. It has been widely used to study the mechanisms of dust storms and their effects on the Martian atmosphere. To better understand the ability of MarsWRF to simulate the dust cycle on Mars, this study assesses the current dust lifting schemes in the model, specifically the convective lifting and wind stress schemes. It is found that, by tuning lifting efficiency, the model with the convective lifting scheme can generally reproduce the seasonal variation of the mid-level atmospheric temperature (T15) but cannot reproduce the observed spatial distribution of dust devils, which exhibits non-homogeneous (uniform) distribution in the northern (southern) hemisphere. The model with the wind stress lifting scheme can generally capture the observed magnitude of T15 and column dust optical depth (CDOD) with properly tuned lifting efficiency and threshold drag velocity. There is a discrepancy in the assessment of modeling seasonal variations of dust with T15 and CDOD, which may be partly due to the observational uncertainties related to T15 and CDOD and the empirical modeling methods of Martian dust optical properties and radiative effect. For the spatial distribution of dust, there are significant simulation biases regardless of the tuning, which may be caused by the biases in the dust lifting process and large-scale atmospheric circulation. The analysis highlights that dust lifting schemes need further improvement to better represent the dust cycle and their impacts on Mars.

Transionospheric radio signals might undergo random modulations of their amplitude and phase caused by scattering on irregular structures in the ionosphere. This phenomenon, known as scintillation, is governed by the space weather conditions, time of the day, season, local distribution of the geomagnetic field, etc. All these factors make ionospheric scintillation both highly variable in space and time. Moreover, scintillation are intrinsically anisotropic since the associated scattering irregularities tend to align and stretch along the geomagnetic field lines. Depending on the relative position of signal source, the receiving station, and the irregularity, the scintillation effect on the transmitted wave might be enhanced or reduced. This study is focused on the consistent accounting of this geometric effect in scintillation modeling with the emphasis on situations when the communication or sensing sender-receiver link is nearly horizontal. For this task the single phase screen model has been used to model the scattering of propagating radio signals on random ionospheric layer. The geometric enhancement effect of scintillation is demonstrated by considering communication links via a geostationary beacon satellite over the equator.

Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) is a space-borne instrument dedicated to monitoring high-energy transients, thereinto Terrestrial Gamma-ray Flashes (TGFs) and Terrestrial Electron Beams (TEBs). We propose a TGF/TEB search algorithm, with which 147 bright TGFs and 4 TEBs are identified during an effective observation time of $\sim$ 9 months. We show that, with gamma-ray and charged particle detectors, GECAM can effectively identify and distinguish TGFs and TEBs, and measure their temporal and spectral properties in detail. Moreover, we find an interesting TEB consisting of two pulses with a separation of $\sim$ 150 ms, which is expected to originate from a lightning process near the geomagnetic footprint. We also find that the GECAM TGF’s lightning-association ratio is $\sim$ 80\% in the east Asia region using the GLD360 lightning network, which is significantly higher than previous observations.

We investigate the effect of extremely rough bathymetry on energy dissipation and mixing in a coastal region characterized by small-scale seafloor features penetrating a strongly-stratified density interface of comparable vertical scale. Our data from the non-tidal Baltic Sea include shear microstructure measurements and observations from a broadband echosounder, here used to resolve the extreme variability and intermittency of stratified turbulence in the vicinity of obstacles. Scale analysis and acoustic imaging of small-scale turbulent motions suggest that the underlying mixing mechanisms are related to topographic wake eddies and, to a smaller extent, to breaking internal waves near the bathymetric features. Vertical diffusivities exceed those at a nearby reference station with smooth bathymetry by up to two orders of magnitude. Our study emphasizes the importance of rough small-scale (< 1 km) bathymetric features for energy dissipation and vertical turbulent transport in coastal areas shaped by e.g., glacial, tectonic, or volcanic processes.

We report the first detection of unrest at Socompa, Northern Chile, a stratovolcano which has recorded no eruptions since ~7,200 years ago. We measure deformation at and around Socompa using Interferometric Synthetic Aperture Radar (InSAR) observations between Jan 2018 and Oct 2021. We find that, whilst initially inactive, Socompa shows a steady uplift (17.5 mm/yr) from Dec 2019, independently recorded by near-field continuous Global Positioning System (GPS) data. The data can be fit with pressure increase in an ellipsoidal source region stretching from 1.9 to 9.5 km, with a volume change rate of ~5.8×106 m3/yr. Our observations of the onset of uplift preclude the possibility that a nearby Mw 6.8 deep intraslab earthquake on 3rd June 2020 triggered the unrest. The deformation signal we detect indicates the initiation of unrest at Socompa, after at least two decades without measurable deformation, and many thousands of years without volcanic activity.

Volcanic hazards associated with lava flows advancing on a snow cover are often underrated. On 16 March 2017, during a mild effusive-explosive eruption at Mt Etna (Italy) a slowly advancing lava lobe interacted with the snow cover producing a sudden, short-lasting sequence of explosions. White vapor, brown ash and coarse material were suddenly ejected, and the products hit a group of people, injuring some of them. The proximal deposit formed a continuous mantle of ash, lapilli and decimetric-sized bombs, and the ballistic material reached up to 200 meters away from the lava edge. A total deposit mass of 7.1 ± 0.8 × 104 kg was estimated, corresponding to a lava volume removed by the explosion of 32.0 ± 3.6 m3. Textural and morphological data on the ejected clasts were used to constrain a model of lava-snow interaction. Results suggest that the mechanism responsible for the explosions was the progressive pressure build-up due to vapor accumulation under the lava flow, while no evidence was found for the occurrence of fuel-coolant interaction processes driving the explosions. Although these low-intensity explosions are not too frequent, the collected data represent a unique dataset which provides useful information on the involved processes and the associated hazard, but also on possible measures of mitigation to prevent potentially dramatic accidents at volcanoes like Etna, recording up to thousands of visitors per day.

Drought alone and with associated abiotic stress such as heat and nutrient deficiency leads to significant agricultural crop loss. Thus, with changing climatic conditions, it is important to develop resilience measures in agricultural systems against drought stress. In this review, we discuss the modifications in plants while responding to drought giving special focus on roots as they are the primary sense organs in this context. Prospects of genomic crop improvement by pointing out the focus areas to engineer root system architecture and genomic regions involved in the related traits are also discussed. We have also listed instruments and software facilitating high throughput phenotyping of root system in field conditions as the phenotyping of root system architecture in the field is a challenge.

Assessing space weather modeling capability is a key element in improving existing models and developing new ones. In order to track improvement of the models and investigate impacts of forcing, from the lower atmosphere below and from the magnetosphere above, on the performance of ionosphere-thermosphere models, we expand our previous assessment for 2013 March storm event [Shim et al., 2018]. In this study, we evaluate new simulations from upgraded models (Coupled Thermosphere Ionosphere Plasmasphere Electrodynamics (CTIPe) model version 4.1 and Global Ionosphere Thermosphere Model (GITM) version 21.11) and from NCAR Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (WACCM-X) version 2.2 including 8 simulations in the previous study. A simulation of NCAR Thermosphere-Ionosphere-Electrodynamics General Circulation Model version 2 (TIE-GCM 2) is also included for comparison with WACCM-X. TEC and foF2 changes from quiet-time background are considered to evaluate the model performance on the storm impacts. For evaluation, we employ 4 skill scores: Correlation coefficient (CC), root-mean square error (RMSE), ratio of the modeled to observed maximum percentage changes (Yield), and timing error(TE). It is found that the models tend to underestimate the storm-time enhancements of foF2 (F2-layer critical frequency) and TEC (Total Electron Content) and to predict foF2 and/or TEC better in the North America but worse in the Southern Hemisphere. The ensemble simulation for TEC is comparable to results from a data assimilation model (Utah State University-Global Assimilation of Ionospheric Measurement (USU-GAIM)) with differences in skill score less than 3% and 6% for CC and RMSE, respectively.

The pore structure of marine sediments varies with the distribution of gas-hydrate, hence affecting the gas-water permeability. CT image is a conventional approach to view the internal structure, while for hydrate-bearing sediment investigation, rather poor resolution of obtained image has limited the accuracy of the analysis. Recently, super-resolution (SR) reconstruction techniques have been used to enhance the spatial resolution of CT images with varying degrees of improvement. Typical Image Pairs-Based SR (PSR) methods require higher resolution matching images for training, which is challenging for hydrate samples in dynamic temperature and pressure conditions. Here, we introduced a self-supervised learning (SLSR) method that only relies on a single input image to complete the process of training and reconstruction. We conducted a complete training to establish an end-to-end network consisting of two sub-networks, an SR network and a downscaling network. Self-built datasets from three hydrate samples with different sediment grains were trained and tested. Compared with the typical method, the SR results show that our method provides higher resolution while improving clarity. Moreover, in the subsequent calculation of porosity parameters, it has the highest consistency with the liquid saturation method. This study contributes to investigating the water seepage and energy transfer in the gas hydrate bearing sediments, which is particularly important for the exploration and development of marine natural gas hydrate resources. The image super-resolution method established by us has also a broad application prospect in the field of CT imaging.

In view of the fact that the practical salinity of the Bohai Sea in January 2007 was significantly higher than the multi-year mean with its horizontal distribution opposite to the latter, the factors that affect the interannual variation of practical salinity in the Bohai Sea are quantitatively analyzed based on the in-situ hydrological measurements, the annual runoff data of the Yellow River into the sea, as well as the precipitation and evaporation reanalysis data of EAR5. The results show that the local freshwater supply not only dominates the magnitude of salinity change in the Bohai Sea, but also causes the salinity in the central Bohai Sea is higher than that in the Bohai Strait in winter in some years which is in inverse to the climatological salinity field. The seesaw distribution characteristics of the freshwater supply of the Bohai, Yellow and East China Seas also strengthen the characteristics that the salinity horizontal distribution opposite to the climatological in the Bohai Sea in some years. Available observations also show that the nutrient and inorganic carbon of the Bohai Sea are much higher than that of the open ocean, which gives a rise of 0.02 ~0.2 g·kg-1 in Absolute Salinity. Therefore, it is necessary to replace the Practical Salinity with the Absolute Salinity for the accurately salinity changes study in the Bohai Sea.

A document by Linying Gao. Click on the document to view its contents.

This paper describes the development of the fluxgate magnetometer on the Fengyun-4B satellite. The Fengyun-4 is the second generation of China’s geostationary orbit satellite with the function of monitoring the space environment in GEO orbit. A fluxgate magnetometer (FGM) is deployed on this satellite to observe the magnetic field as a necessary input to space weather forecasting. This payload adopts three 3-axis fluxgate sensors to obtain space magnetic field data by excluding the satellite’s interference. Each three-axis fluxgate sensor has an independent signal processing circuit. FGM uses digital signal processing technology to acquire magnetic field signals. First, the analog signal is oversampled using a high-speed ADC, then digital signal processing, such as phase-sensitive demodulation, integration, and filtering, is performed inside the FPGA, and the feedback signal is output to the feedback coil through the DAC. This signal processing loop constitutes an ADC system, and the quantization accuracy of the output digital quantity can reach 18 bits. the FGM performs in-orbit calibration during satellite rotation maneuver and Alfven wave events. Comparison with the GOES-16 satellite and Tsyganenko magnetic field model proves FGM to be effective in monitoring the magnetic field of the space environment. Through joint observations with GOES-16 satellite and geomagnetic stations, FY-4B describes the development of a typical magnetic storm on November 4, 2021. The Ground calibration and in-orbit preliminary results show the FY-4B satellite magnetometer outputs 20 bits of digital resolution data at a 30 Hz sampling rate, with the noise lower than 3×10-4nT2/Hz@1Hz in the ±600nT range.