Miracle-dz/UniFAR-FTUs huggingface dataset:
Global litter production, pools, and turnover times: Estimates from measurement data and regression models

Systematic and compatible databases to quantify composition, distribution, and turnover times of carbon in global litter were developed and evaluated. The study employs an integrated approach, estimating related litter pools and fluxes using a variety of data-based and model-based techniques. The analysis includes direct estimates and indirect, or proxy, estimates of litter production and pools; steady-state turnover times are estimated from the two. Proxies for litter production include net primary productivity and root respiration-soil respiration relationships. In addition to implementing a suite of regression models, >1100 published measurements of litter components, along with site characteristics, were integrated into a baseline data set and used to estimate litter production and pools. Historically, global estimates of litter production have ranged from 75 to 135 Pg dm/yr; several estimates from this study suggest values in the middle of this range, from 90 to 100 Pg dm/yr. The estimate of aboveground litter production from the compiled measurements, 39 Pg dm/yr, includes mainly forest, woodland, and wooded grassland; other grassland, shrubland, and xeromorphic communities that occupy ∼25% of the ice-free land surface are unrepresented in the present compilation. Aboveground litter production may be 5–10 Pg dm/yr higher with the inclusion of these ecosystems, and the total, including belowground production, may approach 90–110 Pg dm/year. Two novel production estimates derived from soil- and root-respiration relationships are 93 Pg and 100 Pg dm/yr. These estimates have the major advantage of accounting for both aboveground and belowground litter; the latter is rarely included and can account for a substantial fraction of total production. Production of coarse woody detritus may add ∼12 Pg dm/yr to the fine litter total. The global litter pool has previously been estimated at ∼100 to 400 Pg dm. The fine litter pool estimated here from the measurement compilation is 136 Pg dm. Although this partial estimate includes ecosystems covering just under half the ice-free land surface, it encompasses forests and woodlands which have the largest pools. Inclusion of the remaining ecosystems may add ∼25 Pg, raising the total to ∼160 Pg dm. An additional ∼150 Pg dm is estimated for the coarse woody detrital pool. Global mean steady state turnover times of litter estimated from the pool and production data range from 1.4 to 3.4 years; mean turnover time from the partial forest/woodland measurement compilation is ∼5 years, and turnover time for coarse woody detritus is ∼13 years. By encompassing spatial distribution, composition, and magnitude, along with numerous field measurements, this integrated approach has begun to yield compositional and ecosystem constraints on modeled global and regional litter fields and NPP allocation schemes in ecosystem models.
Quantification of transient CO2 production in a sandy unsaturated zone

Temporal and spatial respiration rates were determined in a 5.7‐m thick, sandy, unsaturated zone over a 550‐day period using measured CO2 concentrations, CO2 fluxes to the atmosphere, moisture contents, and temperatures. Cyclical patterns in CO2 concentrations were measured in duplicate nests of nine gas samplers. Maximum CO2 gas concentrations occurred during the summer (0.85–1.22%), and minimum concentrations occurred during the winter (0.04–0.24%). CO2 gas concentrations decreased with increasing depth during the summer and increased with depth during the winter. A one‐dimensional finite element model was developed to quantify transient respiration rates through the unsaturated zone. The model was calibrated to the measured CO2 concentrations. Temperature and moisture content variations were represented with an analytical expression and linear interpolation of field‐measured values, respectively, in the model. Simulation results provided very good approximations to the field‐measured CO2 concentrations, but predicted CO2 fluxes to the atmosphere were higher than measured. Respiration rates ranged from 5 µg C g−1 d−1 in the soil horizon during the summer to about <10−4 µg C g−1 d−1 in unsaturated sections of the C horizon. A sensitivity analysis showed that the respiration rates in the C horizon must be <10−3 µg C g−1 d−1 and that the majority of the elevated CO2 concentrations in this thick unsaturated zone are the result of respiration in the soil horizon. Overall, roots contribute about 75% of the CO2 in the summer months. O2 gas, microbial analyses, and the distribution of root biomass supported this conclusion. These observations also imply that although microorganisms are present in subsurface environments their in situ activity in this sandy unsaturated zone may be very low.
Arctic sea ice reduction and European cold winters in CMIP5 climate change experiments

European winter climate and its possible relationship with the Arctic sea ice reduction in the recent past and future as simulated by the models of the Climate Model Intercomparison Project phase 5 (CMIP5) is investigated, with focus on the cold winters. While Europe will warm overall in the future, we find that episodes of cold months will continue to occur and there remains substantial probability for the occurrence of cold winters in Europe linked with sea ice reduction in the Barents and Kara Sea sector. A pattern of cold‐European warm‐Arctic anomaly is typical for the cold events in the future, which is associated with the negative phase of the Arctic Oscillation. These patterns, however, differ from the corresponding patterns in the historical period, and underline the connection between European cold winter events and Arctic sea ice reduction.
Backcountry Huts as Introduction Points for Invasion by Non-native Species into Subalpine Vegetation

Abstract The role of backcountry huts as introduction points for the establishment and spread of non-native plants into remote natural areas has received little attention. We surveyed soil and vegetation around 25 backcountry huts in the subalpine landscape of the Australian Alps to examine the role that such huts play in acting as foci for invasion by non-native species into remote mountain areas. We found that the hut surroundings were characterized by greater soil compaction, lower vegetation height, and more bare ground relative to the native plant community located 100 m from huts. At the landscape-scale, a total of 32 non-native species were recorded within 100 m of huts. Seven species were found at greater than 50% of huts (Hypochoeris radicata, Taraxacum officinale, Acetosella vulgaris, Trifolium repens, Cerastium glomeratum, Agrostis capillaris, Poa annua), and these tended to be the species that have (a) been long-established (>50–100 yrs) and (b) are the most frequent in the broader landscape. Hence, huts act to promote these ruderals by providing opportunities for their establishment, but such opportunities are not confined to hut surroundings. Several other non-native species, however, were common around huts but largely absent from the wider landscape (e.g. Anthoxanthum odoratum, Plantago major, Polygonum aviculare, Stellaria media). This suggests that some species are advantaged by the disturbance and dispersal opportunities provided by hut recreational activities in a way that is not catered for elsewhere in the Australian Alps. A weak negative relationship between non-native species richness and increasing altitude was found, but native species richness and distance of hut from access road were poor predictors of non-native species richness. Our study highlights that recreational activities may provide opportunities for the establishment of non-native plant species in remote high mountain areas, some of which are novel to the landscape, and that these may form the basis for further invasion into adjoining native vegetation.
Quantitative evaluation of the post-Mount Pinatubo NO2 reduction and recovery, based on 10 years of Fourier transform infrared and UV-visible spectroscopic measurements at Jungfraujoch

The colocation of two technically different instruments for ground-based remote sensing of NO2 total column amounts at the primary Network for the Detection of Stratospheric Change Alpine station of the Jungfraujoch (46.5°N, 8.0°E) has been exploited for mutual validation of the long-term NO2 time series from both instruments and for a quantitative evaluation of the impact of the Mount Pinatubo eruption on the NO2 abundance above this northern midlatitude observatory. The two techniques are high-resolution Fourier transform infrared solar absorption spectrometry and zenith-sky differential optical absorption spectroscopy in the UV visible. The diurnal variation of NO2 has been simulated by a simple photochemical model that allows a comparison between the data from the two techniques. This model is shown to reproduce the observed morning to evening ratios to 2.3%, on average, which is fully adequate for the needs of this study. From the 1985–1996 combined time series of NO2 morning and evening abundances, it has been concluded that the enhanced aerosol load injected into the stratosphere by Mount Pinatubo caused a maximum NO2 reduction above the Jungfraujoch by 45% in early January 1992 that died out quasi-exponentially to zero by the beginning of 1995.
Laboratory Studies of Surface Waves Using a Laser Doppler Vibrometer

We have performed physical modeling of surface waves using a laser Doppler vibrometer (LDV). Surface wave methods have been applied to both engineering and earth science problems to image S-wave velocity of the Earth. In order to develop the surface wave methods, numerical and physical modelings of surface waves are important. The LDV converts a particle velocity of media to the Doppler shift frequency，and enables us to measure very precise ultrasonic waves. A piezoelectric transducer (PZT) was used as a source of elastic waves. 50KHz to 500KHz elastic waves were observed by using the LDV and PZT. We have measured surface waves propagating a homogeneous half space models and horizontal two-layer models using the LDV and PZT. Theoretical characters of surface waves，such as Rayleigh wave dispersion, have been clearly observed by the physical modeling.
Variation of transition zone high‐velocity anomalies and depression of 660 km discontinuity associated with subduction zones from the southern Kuriles to Izu‐Bonin and Ryukyu

The seismic structure of the transition zone beneath the northwestern Pacific ocean is studied by comparing regional distance seismic waveforms with synthetic seismograms. By modeling waveforms we incorporate the travel times of secondary waves that are not included in traveltime data used in most P wave tomography experiments. These secondary waves are highly sensitive to the velocity above the 660 km discontinuity and thus add information on the seismic structure of the transition zone independent of that used in many tomography experiments. We used just two one-dimensional models in the waveform comparison. The iasp91(slightly modified in the shallower depths as aiasp) is used as a global average structure, and model M3.11 is used as representative of transition zone structure near a deep subducting slab. Model M3.11 is faster than iasp91 from 525 to 660 km depth but also has a 30 km deeper “660” km discontinuity. Our results show strong variations in the transition zone structure beneath the northwestern Pacific. Data that sample beneath the northwestern Japanese subduction zone and the southern Kuriles are well fit by model M3.11. The deep structure beneath the Bohai Sea, to the west of Korea, also appears to show slab-related velocity anomalies in the transition zone. In contrast, the seismic data sampling beneath the Yellow Sea to the East China Sea are better modeled using the global average model iasp91. Data that sampled beneath the Philippine Sea showed evidence for anomalously high velocity in the transition zone, but there is little apparent change in the depth of the 660 km discontinuity there. The overall results are in agreement with past work indicating fairly broad regions where subducting plate is lying flat or piling up within the transition zone, although we find that the region where this occurs, and thus the total volume of slab within the upper mantle, is considerably less than that seen in past studies. The unusual structure beneath the Philippine plate may be due to the relatively recent descent of slab beneath this region. The slab itself is cold, and thus anomalously fast, but the deeper mantle may not have cooled enough for the 660 km discontinuity to have deepened.
Distribution of polygon characteristic scale in Martian patterned ground terrain in the northern hemisphere using the Fourier transform

Permafrost patterned ground forms on the surface of nearly all landscapes between 50°N and 70°N on Mars. This landform appears in satellite imagery as an interconnected network of polygonal shapes. Previous studies used geomorphologic observations to characterize patterned ground terrains on Mars. These classification systems prove useful but suffer from somewhat subjective methods. We find objective analysis of the polygons comprising patterned ground terrains on the surface of Mars feasible using High Resolution Imaging Science Experiment imagery acquired from orbit. We perform a two‐dimensional Fourier transform on 124 images of patterned surfaces to characterize the spatial scale pertinent to scenes and analyze the distribution of these properties on the surface of Mars between 50°N and 70°N. We find two distinct sets of polygons: large polygons which form below 60°N and small polygons primarily above 60°N with exception for sites within Acidalia Planitia. Our findings show similar trends to those found in previous studies but also fundamental differences in the populations of polygons above and below 60°N. The polygons within 60°N–70°N share roughly the same polygonal scale, implying that seasonal temperature change is not the only factor forcing polygon development as previous models found. In some cases, our method indicates the presence of multiple scales of polygons, although it cannot quantify the larger scale. This method in conjunction with observational analysis improves our ability to characterize surfaces and examine patterned ground terrains on Mars.
Mars W cloud: Evidence of nighttime ice depositions

Water clouds on Mars, their current and past connections with other forms of water, along with surface features that suggest the early existence of flowing water, continue to be intriguing aspects of the red planet. Discrete afternoon mountain clouds were one of the earliest atmospheric features to be observed on Mars. Their exclusive formation near the high mountains led to the common belief that air lifting associated with local circulation induced by the mountains underlies their formation. We demonstrate that an additional local source of water vapor is needed for the formation of opaque discrete afternoon clouds on the mountains of Mars, including the so‐called W‐formation. We suggest that the possible deposition of ice from the thick aphelion cloud belt during the night is capable of providing this additional source. This direct cloud water deposition on mountains on Mars bears many similarities with the well‐known interception of water by mountains frequently immersed in fogs on Earth.
Research on Dynamic Gesture Recognition with Low-Pixel ToF-Sensors

Low-pixel time-of-flight (ToF) sensors offer advantages in low power consumption, small size, and low cost. For gesture recognition, there are two advantages. Firstly, they are robust to changes in lighting conditions. Secondly, they could protect privacy. This paper addresses the challenge of utilizing an $\mathbf{8}\times \mathbf{8}$ pixel ToF sensor with extremely low resolution by proposing a signal processing system. The system includes pre-processing the data through non-global mean filtering to calibrate outliers. Additionally, we design a frames difference sliding window to ensure the integrity of gesture sequences and use Lagrangian interpolation to norm the fixed length. Finally, we design a tiny parallel convolutional network (TPC-Net) to recognize dynamic gestures. Experimental results demonstrate that the proposed system achieves an average accuracy of 98.47% over 6 dynamic gestures. Furthermore, our system achieves better performance with less model complexity compared to existing methods using low-pixel ToF sensors. These results illustrate the effectiveness of our system.
Periodic changes of stream flow in the last 40 years in Tarim River Basin, Xinjiang, China

Using the annual runoff series for the last 40 years from the Tarim River Basin, their periodic properties were analysed and their future trends predicted. Runoff data were collected at five hydrological gauging stations in the three main branches of the Tarim River. An extrapolation method and variance analysis were used to identify periods in annual runoff, and a trend superposition model to predict future changes. Results show that, there is a common period of 17 years in annual runoff changes for all three branches, with Hotan River showing an additional period of 10 years. Based on this trend, it is suggested that the annual runoff of the Tarim River should decrease in the period of 2006–2008, but increase in year 2009, and the flow may possibly begin to decrease significantly in year 2010. The long term trend of runoff in Tarim Basin has followed the global prediction of GCMs, i.e. began to increase in accordance with global increase of air temperature and precipitation in 1990. However, it has shown a local feature of uneven changes among the head streams in the same basin, which needs to be further investigated. Copyright © 2008 John Wiley & Sons, Ltd.
A Decomposition-Based Dynamic Reference Vector Adaptive Evolution Algorithm

Many predefined and improperly adjusted reference vectors in decomposition-based algorithms are invalid on irregular Pareto fronts (PFs). A dynamic reference vector adjustment based on a decomposition-based multi-objective evolutionary algorithm (DDMOEA) is proposed in this paper to address this problem. The algorithm separates the multi-objective problem into several sub-problems and sorts them according to dominance and diversity. A dynamic reference vector adjustment strategy is applied to guide the search area and obtain a set of optimal solutions that reflect PFs. By dynamically adjusting the reference vector, useless or overly close reference vectors can be deleted, and new reference vectors reflecting PFs can be generated, which is more conducive to the search process of the population. The proposed DDMOEA can improve the partitioning of sub-spaces and the performance of many objective problems with irregular PFs while considering computational complexity. In addition, in many objective optimization problems, the neighborhood adaptive strategy used in the algorithm reduces selection pressure while ensuring diversity. Experimental results prove that this algorithm can overcome multi-objective optimization problems with various categories of PFs compared to several of the most relevant algorithms.
Measuring sheet erosion using synthetic color‐contrast aggregates

The bulk of eroded soils measured at the outlets of plots, slopes and watersheds are suspended sediments, splash‐induced sheet erosion. It is depending on rainfall intensity and antecedent soil moisture contents and contributes to a significant proportion of soil loss that usually is ignored in soil erosion and sediment studies. A digital image processing method for tracing and measuring non‐suspended soil particles detached/transported by splash/runoff was therefore used in the present study. Accordingly, fine mineral pumice grains aggregated with white cement and coloured with yellow pigment powder, with the same size, shape and specific gravity as those of natural soil aggregates, called synthetic color‐contrast aggregates, were used as tracers for detecting soil particle movement. Subsequently, the amount of non‐suspended soil particles detached and moved downward the slope was inferred with the help of digital image processing techniques using MATLAB R2010B software (Mathworks, Natick, Massachusetts, USA). The present study was conducted under laboratory conditions with four simulated rainfall intensities between 30–90 mm h‐1, five antecedent soil moisture contents between 12–44 % v v‐1 and a slope of 30%, using sandy loam soils taken from a summer rangeland in the Alborz Mountains, Northern Iran. A range of total transported soil between 90.34 and 1360.93 g m‐2 and net splash erosion between 36.82 and 295.78 g m‐2were observed. The results also showed the sediment redeposition ratio ranging from 87.27% [sediment delivery ratio (SDR) = 12.73%] to 96.39% (SDR = 3.61%) in various antecedent soil moisture contents of rainfall intensity of 30 mm h‐1 and from 80.55% (SDR = 19.45%) to 89.42% (SDR = 10.58%) in rainfall intensity of 90 mm h‐1. Copyright © 2013 John Wiley & Sons, Ltd.
Recognition of Dynamic Grasping Motion through Feature Extraction for Teleoperation

Detecting human movement intentions and transmitting human operational capabilities to robots is of great significance for teleoperations. However, the difference in kinematic structure between human hands and robotic manipulators brings difficulties to teleoperation mapping. In this paper, we present an approach to hand grasp recognition and mapping based on feature extraction to drive heterogeneous remote manipulator. The hand grasp data set HUST recorded with a data glove was used for this study. The data were preprocessed and their features were extracted by PCA. A neural network-based classifier was obtained through offline training of human grasping activities. We compared different network models and selected the network with the best performance based on the training time and the task requirements of teleoperation. The experimental results showed that the recognition accuracy of dynamic grasping motion with feature extraction is higher than that without feature extraction and can be up to 97.47%. Finally, we validated the feasibility of this method to tele-operate an Barrett hand through online experiments. Our proposed method provides an effective approach of mapping natural human grasping operations to heterogeneous robotic teleoperation systems.