Average Effective Temperature Research Articles

Features of the Development of Tropical Crops in the Conditions of Dry Subtropics of the Southern Coast of the Crimea

Aerva lanata (L.) Juss. and Passiflora incarnata L. are pharmacopoeial medicinal plants, the raw materials of which are included in the list of imported to the Russian Federation. We conducted the complex of ecological and biological studies in order to select the optimal method of culture (long-term or annual) of these crops and assess the prospects of their cultivation in the conditions of the Southern Coast of the Crimea. In accordance with the methods of introduction study, we revealed the features of biology, growth dynamics and development of plants Aerva lanata and Passiflora incarnata in a dry subtropical climate of the Mediterranean type. It was found that for the cultivation of Passiflora incarnata for the long-term type, the required heat resource higher than 10˚С is 2159˚С. Aerva lanata in the open ground of the annual type forms fully valid seeds with heat supply in the 1870˚С. The biologically necessary amount of heat of the open ground culture is provided by the average long-term effective temperatures for Passiflora incarnata at 97% and Aerva lanata – 98-100%. These species are classified as promising species based on the total number of points.

Multiwavelength Observations of a B-class Flare Using XSM, AIA, and XRT

We present multiwavelength observations by Chandrayaan-2/Solar X-ray Monitor, Solar Dynamics Observatory/Atmospheric Imaging Assembly, and Hinode/X-Ray Telescope (XRT) of a B-class flare observed on 2021 February 25, originating from an active region (AR 12804) near the northwest limb. The microflare lasts for ∼30 minutes and is composed of hot loops reaching temperatures of 10 MK. We report excellent agreement (within 20%) for the average effective temperatures obtained at the flare peak from all the three instruments, which have different temperature sensitivities. The XRT filter combination of Be-thin and Be-med provides an excellent opportunity to measure the high temperatures in such microflare events. The elemental abundances during the evolution of the microflare are also studied and observed to drop toward photospheric values at the flare peak time, compared to coronal values during the rise and decay phase. This is consistent with previous XSM studies.

Multiplicity Dependence of the Freeze-Out Parameters in Symmetric and Asymmetric Nuclear Collisions at Large Hadron Collider Energies

Strange hadron transverse momentum spectra are analyzed in symmetric pp and PbPb and asymmetric pPb collision systems for their dependence on rapidity and event charged-particle multiplicity. The thermodynamically consistent Tsallis models with and without flow velocity are used to reproduce the experimental data, extracting the freeze-out parameters to gain insights into the underlying physics of the collision processes by looking into the parameters change with different multiplicities, particle types, and collision geometries. We found that with an increase in the event multiplicity, the average transverse flow velocity, effective, and kinetic freezeout temperatures increase, with heavier strange particle species exhibiting a more significant increase. The value of the non-extensivity parameter decreases with an increase in the multiplicity of the particles. For heavier particles, larger Teff and T0 and smaller q have been observed, confirming the quick thermalization and equilibrium for massive particles. Furthermore, the differences in parameter values for particle species are more significant in pp and pPb collisions than in PbPb collisions. In addition, in symmetric pp and PbPb collisions, parameter values (q,T0,βT) show more significant shifts for heavier particles compared to the lighter ones. In contrast, in asymmetric pPb collisions, both heavier and lighter particles display uniform linear progression.

Importance of Stress and Temperature-Dependent Permeability of Rocks and its Application in Underground Nuclear Waste Disposal

Water flow is an essential factor in the sealability of any underground cavern, including those for nuclear waste disposal, and is significantly affected by the permeability of the rock. The permeability of rocks is affected by various factors, including stress and temperature. The rock stress changes by excavating a cavern, and rock temperature changes by decay heat from nuclear waste, and the temperature change induces thermal stress. Therefore, water flow around such caverns must be evaluated considering the effects of stress and temperature. Numerical analyses of water migration around underground nuclear waste disposal caverns have been carried out. However, studies considering the stress and temperature-dependent permeability may not be published yet. To demonstrate the necessity to consider the stress and temperature-dependency in permeability, equations that represent the post-failure permeability as a function of average effective stress and temperature were proposed. The water inflow was numerically calculated for a simple underground nuclear waste disposal cavern with or without stress and temperature dependency which showed the significance of the dependency. Also, the importance of rock types was demonstrated by considering the three rocks of granite, sandstone, and tuff for a full-scale underground radioactive disposal site for the stress and temperature-dependent permeability. A high sealability could be expected for granite and sandstone but not for the tuff. Introducing the stress and temperature-dependent permeability could contribute to the thoughtful design of an underground repository for radioactive waste disposal considering rock types.

Optimizing relative root-zone water depletion thresholds to maximize yield and water productivity of winter wheat using AquaCrop

Determination of relative root-zone water depletion (RRWD) thresholds to trigger irrigation is crucial to create optimal irrigation schedules targeting maximum yield and/or water productivity with limited water supply for a crop. In this study, a numerical procedure to determine RRWD thresholds was developed through coupling AquaCrop software with genetic-simplex algorithms. Using a two-year field lysimetric experiment for winter wheat conducted in the North China Plain (NCP), AquaCrop adequately simulated canopy cover, final aboveground biomass, grain yield, seasonal evapotranspiration, and soil water storage, with the normalized root mean squared error (NRMSE) smaller than 15 % and determination coefficient (R2) larger than 0.84. The global optimum range of RRWD thresholds was preliminarily determined using the genetic algorithm, and subsequently final RRWD thresholds were optimized by fine tuning using the simplex algorithm. The RRWD threshold combinations (composed of the RRWD thresholds to trigger different sequential irrigation events) for varying number of irrigation events (i.e.1–4) were optimized based on 39 years of historical meteorological data, and the effects of climate change on the optimal crop yield (Ya, opt), water productivity (WPopt), and the combinations of optimized RRWD threshold (RRWDopt) were investigated. The results indicated that both Ya, opt and WPopt generally increased with time showing a tendency of gradually elevated annual CO2 concentration and seasonal average effective temperature. Irrespective of the number of irrigation events during the winter wheat growing season, the differences of RRWDopt for different combinations of irrigation sequence and event in the same kind of hydrological year were relatively small, with a coefficient of variation consistently less than 23 % and a mean of 8 %. When combinations of mean RRWDopt were applied into AquaCrop to trigger irrigation for winter wheat in various hydrological years, the simulated yield (Ya, sim) and water productivity (WPsim) under 1–4 irrigation events were found to be comparable to their respective optimums (Ya, opt and WPopt), with all the values of Ya, sim (WPsim) falling in the range of 92 %Ya, opt (90 %WPopt). Therefore, the mean RRWDopt should be helpful to formulate rational irrigation management strategies of winter wheat under changing climatic conditions in the NCP.

Effects of irrigation regime on soil hydrothermal microenvironment, cotton biomass, and yield under non-film drip irrigation system in cotton fields in southern Xinjiang, China

Non-film drip irrigation cotton planting mode can effectively solve the problem of residual film pollution in arid areas and promote sustainable agricultural development. However, the research on the efficient irrigation regime and soil hydrothermal microenvironment suitable for non-film drip irrigation cotton planting is scarce. Considering this, using the data monitoring technology based on internet of things sensors, we set 3 different irrigation treatments in 2020–2021. In the flowering and boll setting stage, cotton was watered for 4 times (W4), 6 times (W6), and 8 times (W8) with a single irrigation amount of 69 mm for each of these 3 treatments, and the last time irrigation amount under W8 treatment was 52.2 mm. At the seedling stage, the cotton was not irrigated under each treatment. At the squaring stage, the irrigation times and single irrigation amount were the same under each treatment. The results showed that the average soil water content (SWC) in the 50–110 cm soil layer was increased obviously with the increase in the total irrigation amount. Compared with W4 and W8 treatments, W6 treatment exhibited the highest the soil temperature in the 10–30 cm soil layer in the full boll stage and boll opening stage and the highest soil effective accumulated temperature (SEAT) from initial flowering stage to boll opening stage. The reproductive organ allocation rate in two years was 3.6 % and 2 % higher under W6 than under W8, respectively. With the increase of total irrigation amount, the cotton yield was increased, but the irrigation water use efficiency (IWUE) was decreased. The highest cotton yield was achieved under W8 treatment, but it was not significantly different from that under W6 treatment, while IWUE was significantly lower under W8 than under W6. The effective air temperature (EAT) had the greatest positive impact on the average effective soil temperature (EST) in 10–50 cm soil layer, while the cumulative irrigation amount (CIA) had a negative impact on average EST in 10–50 cm soil layer. Evapotranspiration (ET) and SEAT were positively correlated with biomass accumulation amount and lint yield. In summary, the irrigation regimes of 2 times of irrigation at the squaring stage with a single irrigation amount of 45 mm and 6 times of irrigation at the flowering and boll setting stage with a single irrigation amount of 69 mm can be applied to the non-film cotton cultivation mode in southern Xinjiang. Our findings provide a reference for the application of agricultural internet of things technology in soil hydrothermal microenvironment of non-film cotton fields in Xinjiang.

On the influence of meteorological factors on population health in the conditions of the Kamchatsky Region

In the context of the intensification of the development of Kamchatka, the assessment of its comfort in terms of weather and climatic conditions is updated to prevent the influence of meteorological indicators on the health of the population. According to indicators for 2010–2020 air temperature (average and minimum), wind (average and maximum), relative humidity assessed the bioclimatic comfort of Petropavlovsk-Kamchatsky as a health risk factor. At an average temperature, the warm period of the year is June-September, there is no cold one; minimum — warm in August, cold in December-March. Average wind is strong (5 months) and strong to very strong (7 months); maximum — strong (7 months), from strong to very strong (5 months); in gusts —very strong (3 months), from very strong to stormy (6 months). The air from October to April is moderately dry, then moderately humid. With average meteorological indicators for effective temperature, the warm period of the year is in July-August (September could be both warm and transitional), cold — December-March. At the minimum temperature and maximum wind, there is no warm period of the year, cold — October-May. The influence of physical factors is inadequate for the body: uncomfortable positive temperatures in June-September, high humidity (May-September), year-round strong winds. According to the effective temperature, determined from the average values of physical factors, the warm season is shorter by 2 months, the cold 4 months. At the minimum temperature and maximum wind in the summer season, habitat conditions refer to the transition period, 8 months. to the cold season. There is no health risk based on average effective temperature data; at extreme values, the risk of cold injury within 3 months. (January, February — absolute, December — possible); with increased wind, the risk arises in the month of March.

Variability of soybean yield and seed quality depending on environmental hydrothermal factors

Variability of soybean yield and seed quality depending on environmental hydrothermal factors

A 50-nm Gate-Length Metamorphic HEMT Technology Optimized for Cryogenic Ultra-Low-Noise Operation

This article reports on the investigation and optimization of cryogenic noise mechanisms in InGaAs metamorphic high-electron-mobility transistors (mHEMTs). HEMT technologies with a gate length of 100, 50, and 35 nm are characterized both under room temperature and cryogenic conditions. Furthermore, two additional technology variations with 50-nm gate length are investigated to decompose different noise mechanisms in HEMTs. Therefore, cryogenic extended Ku-band low-noise amplifiers of the investigated technologies are presented to benchmark their noise performance. Technology C with a 50-nm gate length exhibits an average effective noise temperature of 4.2 K between 8 and 18 GHz with a minimum of 3.3 K when the amplifier is cooled to 10 K. The amplifier provides an average gain of 39.4 dB at optimal noise bias. The improved noise performance has been achieved by optimization of the epitaxial structure of the 50-nm technology, which leads to low gate leakage currents and high gain at low drain current bias. To the best of the authors' knowledge, this is the first time that an average noise temperature of 4.2 K has been demonstrated in the Ku-band.

Bioclimatic characteristics of the regions of the Russian region from the standpoint of assessing the health risk of the population by effective temperature

We calculated the effective temperatures based on 10-year data for temperatures (monthly average and minimum), wind speeds (monthly average and maximum) and relative air humidity in the climatic zones of the Krasnoyarsk Territory (subarctic No. 1) and temperate continental (Krasnoyarsk (object No. 2) and Minusinsk (3) We assessed the health risk.In winter, in the subarctic zone, the temperature is –23.3 ± 1.5 0 C (minimum –30.2 ± 2.1 0 C), in object No. 2 — –17.3 ± 1.6 0 C (–19.3 ± 1.0 0 С) and object No. 3 — –19.9 ± 1.4 0 С (–25.5 ± 1.9 0 С). In spring at object No. 1 it varied from –16.5 ± 1.7 0 С to + 1.6 ± 1, 0 0 С, object No. 2 — from –3.9 ± 0.9 0 С to + 9.4 ± 0.5 0 С, object No. 3 — from –4.5 ± 0.9 to + 10.6 ± 0.4. Temperatures ranged from + 8.2 ± 0.9 0 C to –17.8 ± 1.2 0 C (object No. 1), from + 9.4 ± 0.5 0 C to –7.5 ± 0.9 0 C and from +10.4 ± 0.4 0 C to –6.4 ± 1.0 0 C. In summer, the temperature was 19.9 ± 0.9 0 C, 18.8 ± 0.3 0 C, and 19.8 ± 0.4 0 C, respectively. Wind speed at object No. 3.6 ± 0.05 m/s in July increased to 5.4 ± 0.2 m/s in December (maximum 16.2 m/s); No. 2 in July 1.4 ± 0.05 m/s, in October-May 1.8 ± 0.2–2.1 ± 0.07 (maximum in December 10.1 ± 0.1 m/s); No. 3 minimum wind in January and February (1.1 ± 0.1 m/s), maximum 10.7 ± 0.6 m/s in May. A moderately dry climate is recorded during 2, 4 and 5 months. In the conditions of Krasnoyarsk and Minusinsk in the spring, humidity drops to the limits of dry air. Average effective temperatures indicated a possible risk of frostbite in the subarctic zone after 20–30 minutes within 2 months; at minimum temperatures and maximum winds in March, frostbite in 20–30 minutes, in November, December and February in 10–25 minutes; in January — in 5 minutes. In the Krasnoyarsk region in January frostbite is possible within 20–30 minutes, in Minusinsk in February in 20–30 minutes, in January 10–15 minutes. Heat stress is undefined.

Study of Production of (Anti-)deuteron Observed in Au+Au Collisions at s NN = 14.5 , 62.4, and 200 GeV

Transverse momentum distributions of deuterons and antideuterons in Au + Au collisions at s NN = 14.5 , 62.4, and 200 GeV with different centrality are studied in the framework of the multisource thermal model. Transverse momentum spectra are conformably and approximately described by the Tsallis distribution. The dependence of parameters (average transverse momenta, effective temperature, and entropy index) on event centrality is obtained. It is found that the parameters T increase and q decrease with increase of the average number of particles involved in collisions, which reveals the transverse excitation degree increases with collision centrality.

Density, Alternative Determinant of Star Formation Efficiency of the Milky Way GMCs: Core Reason for Low Star Formation Efficiency

The overall efficiency with which Milky Way Giant Molecular Clouds (GMCs) is forming stars was determined by deriving an equation using density of cloud (i.e. stellar density/ total cloud density), which is the core parameter that determines star formation other than the mass of cloud, and comparing with mass (i.e. stellar mass/ total gas mass) as was propounded by previous researchers, to ascertain the reasons the observed star formation efficiency of Milky Way Giant Molecular Clouds (ϵ_GMC) is low. This will aid understanding the physical factors behind the formation of stars from interstellar gas and develop a predictive theory of star formation and evolution of galaxies. A total of 191 star formation complexes-giant molecular cloud (SFC-GMC) complexes was used in estimating the following cloud parameters: density as 93.8218 solar mass/parsec squared, average stellar density as 2.67872 solar mass/parsec squared, average luminosity as 9.87E24 solar luminosity, average effective temperature as 498,647 solar temperature, average stellar radius as 51.4522 parsec and average cloud radius as 325507 parsec as well as the total mass in stars M_⋆ harbored by the individual clouds (20,831 solar mass), which was inferred from Wilkinson Microwave Anisotropy probe (WMAP) free-free. Finally, the overall efficiency with which Milky Way Giant Molecular Clouds is forming star gave 0.0289573 which is less than the previous estimate as 0.030849, showing that not all the masses of the cloud were present at the end of the star formation, and this reduction in mass are caused by magnetic field, supersonic turbulence, self-regulation and unbound states of its internal structure, which are the reasons the observed star formation efficiencies are low.

Middle aged γ-ray pulsar J1957+5033 in X-rays: pulsations, thermal emission, and nebula

Abstract We analyse new XMM–Newton and archival Chandra observations of the middle-aged γ-ray radio-quiet pulsar J1957+5033. We detect, for the first time, X-ray pulsations with the pulsar spin period of the point-like source coinciding by position with the pulsar. This confirms the pulsar nature of the source. In the 0.15–0.5 keV band, there is a single pulse per period and the pulsed fraction is ≈18 ± 6 per cent. In this band, the pulsar spectrum is dominated by a thermal emission component that likely comes from the entire surface of the neutron star, while at higher energies (≳0.7 keV) it is described by a power law with the photon index Γ ≈ 1.6. We construct new hydrogen atmosphere models for neutron stars with dipole magnetic fields and non-uniform surface temperature distributions with relatively low effective temperatures. We use them in the spectral analysis and derive the pulsar average effective temperature of ≈(2–3) × 105 K. This makes J1957+5033 the coldest among all known thermally emitting neutron stars with ages below 1 Myr. Using the interstellar extinction–distance relation, we constrain the distance to the pulsar in the range of 0.1–1 kpc. We compare the obtained X-ray thermal luminosity with those for other neutron stars and various neutron star cooling models and set some constraints on the latter. We observe a faint trail-like feature, elongated ∼8 arcmin from J1957+5033. Its spectrum can be described by a power law with a photon index Γ = 1.9 ± 0.5 suggesting that it is likely a pulsar wind nebula powered by J1957+5033.

Research on the Internal Thermal Boundary Conditions of Concrete Closed Girder Cross-Sections under Historically Extreme Temperature Conditions

The accuracy of the finite element model (FEM) for concrete closed girder cross-sections is significantly influenced by thermal boundary conditions. The internal thermal boundary conditions can be simulated by inputting the convection heat transfer coefficient and the temperatures inside the cavities or by establishing air elements in the FEM. In order to analyze the influence of different simulation methods for the internal thermal boundary conditions on temperature distributions for concrete closed girder cross-sections, the temperature distributions on the cross-sections of a box girder, small box girders, and adjacent box girders were monitored, and the corresponding FEMs were implemented. By comparing the temperature data obtained from the field test and FEMs, the numerical hourly temperature curves calculated by using the measured temperatures inside the cavities provide the closest agreement with the measured results; however, the measurements of the temperatures on site are cost- and time-prohibitive. When there is a lack of measured temperatures inside the cavities, the numerical hourly temperature curves calculated by establishing air elements in the FEM provide the closest agreement. The influences of different simulation methods for the internal thermal boundary conditions on the highest hourly average effective temperatures and the trends of the vertical temperature gradients for concrete closed girder cross-sections were small. The FEM with air elements can be adopted to analyze the temperature distributions on concrete closed girder cross-sections under historically extreme temperature conditions. It can be predicted that the longitudinal thermal movement of concrete closed girders would be underestimated by considering variations in the one-year measured average effective temperature of the cross-sections or the Chinese-code-specified design effective temperature for the highway bridge structures, which are thus unconservative for engineering applications. The Chinese-code-specified design vertical temperature gradients are conservative for the bridge deck surface and unconservative for the bottom flange.

The chemical composition of HIP 34407/HIP 34426 and other twin-star comoving pairs

ABSTRACT We conducted a high-precision elemental abundance analysis of the twin-star comoving pair HIP 34407/HIP 34426. With mean error of 0.013 dex in the differential abundances (Δ[X/H]), a significant difference was found: HIP 34407 is more metal rich than HIP 34426. The elemental abundance differences correlate strongly with condensation temperature, with the lowest for the volatile elements like carbon around 0.05 ± 0.02 dex, and the highest up to about 0.22 ± 0.01 dex for the most refractory elements like aluminium. Dissimilar chemical composition for stars in twin-star comoving pairs is not uncommon, thus we compile previously published results like ours and look for correlations between abundance differences and stellar parameters, finding no significant trends with average effective temperature, surface gravity, iron abundance, or their differences. Instead, we found a weak correlation between the absolute value of abundance difference and the projected distance between the stars in each pair that appears to be more important for elements that have a low absolute abundance. If confirmed, this correlation could be an important observational constraint for binary star system formation scenarios.

Field Analysis of three different Silicon-based Technologies in Composite Climatic Condition

This paper investigates the performance of the photovoltaics based on the filtering techniques, performance monitoring metrics, and numerical methodologies at real outdoor conditions. The experimental study is carried out on a set of nine photovoltaics modules consisting three modules of each technology i.e. Multi-crystalline (mc-si), Heterojunction with Intrinsic Thin layer (HIT) and Amorphous Silicon (a-si). Various electrical performance data has been collected and characterized for a period of three years in the composite climate of India. The research methodology includes mapping of series resistance, estimation of monthly average effective peak Power (Peff), Performance Ratio (PR) and temperature corrected Performance Ratio (PRT_CORR) has been carried out. The average percentage reduction in the effective peak power (ΔPeff) for the mc-si, a-si and HIT modules were 15.8%, 17.2%, and 7.1% respectively over a period of three years. The monthly average PR for mc-si, a-si and HIT modules were 0.70, 0.82 and 0.83 respectively for the same period. The PR T_CORR over three-year duration for mc-si is 0.77, for a-si is 0.89, and 0.90 for a HIT modules respectively. The annual degradation is 1.5%, 1.6% and 0.39% for mc-si, a-si and HIT modules respectively. The increment in the series resistance has been calculated estimated using the procedure I of the IEC 60,891 Edi 2.0 and the mapping of the series resistance has been done with the matrix of in-plane irradiance and module temperature. Further, the uncertainty calculations of series resistance have been estimated for three different irradiation ranges i.e. 1000 W/m2, 900 W/m2 and 800 W/m2 which is around 4% to ensure the sanctity of measurements and calculations. It has been observed that module degrades faster in hot climatic zones. The interpretation of measured and calculated results, correlation of bus-bar corrosion, and module degradation have been delineated for the composite climate. Finally, it also discusses the usage of the above-proposed methods/tools for optimization of solar cell design parameters at different climatic conditions.

Quantitative Study of Using Piloti for Passive Climate Adaptability in a Hot-Summer and Cold-Winter City in China.

There has been an insufficient study of passive climate adaptability that considers both the summer and winter season for the outdoor thermal environment of hot-summer and cold-winter cities. In this study, we performed a quantitative simulation to research the passive climate adaptability of a residential area, considering piloti as the main method for climate adaptation in a hot-summer and cold-winter city in China. Numerical simulations were performed with a coupled simulation method of convection, radiation, and conduction. A cubic non-linear k–ε model proposed by Craft et al. was selected as the turbulence model and three-dimensional multi-reflections of shortwave and longwave radiations were considered in the radiation simulation. Through the simulation, we found that setting the piloti at the two ends of the building was the optimal piloti arrangement for climate adaptation. Then the relationship between the piloti ratio (0%, 20%, 40%, 60%, and 80%) and the outdoor thermal environment was studied. It could be concluded that with the increasing piloti ratio, the wind velocity increased, the mean radiant temperature (MRT) decreased slightly, and the average standard effective temperature (SET*) decreased to 3.6 °C in summer, while in winter, with the increasing piloti ratio, the wind velocity, MRT, and SET* changed slightly. The wind environment significantly affected the SET* value, and the piloti ratio should be between 12% and 38% to avoid wind-induced discomfort.

LSPM J1314+1320: An Oversized Magnetic Star with Constraints on the Radio Emission Mechanism

Abstract LSPM J1314+1320 (=NLTT 33370) is a binary star system consisting of two nearly identical pre-main-sequence stars of spectral type M7. The system is remarkable among ultracool dwarfs for being the most luminous radio emitter over the widest frequency range. Masses and luminosities are at first sight consistent with the system being coeval at age ∼80 Myr according to standard (nonmagnetic) evolutionary models. However, these models predict an average effective temperature of ∼2950 K, which is 180 K hotter than the empirical value. Thus, the empirical radii are oversized relative to the standard models by ≈13%. We demonstrate that magnetic stellar models can quantitatively account for the oversizing. As a check on our models, we note that the radio emission limits the surface magnetic field strengths: the limits depend on identifying the radio emission mechanism. We find that the field strengths required by our magnetic models are too strong to be consistent with gyrosynchrotron emission but are consistent with electron cyclotron maser emission.

Response of vegetation to different time-scales drought across China: Spatiotemporal patterns, causes and implications

Based on Normalized Difference Vegetation Index (NDVI) and Standardized Precipitation Evapotranspiration Index (SPEI), we investigated vegetation response to different time-scales drought across different vegetation types and homogeneous clusters in China, by annual maximum Pearson correlation (Rmax) and the corresponding time-scales of drought. Results showed that: (1) 8 subregions with homogeneous climate-vegetation conditions were identified using Fuzzy C-Means algorithm; (2) SPEI and NDVI's annual Rmax were in significantly positive correlation in most regions of China, indicating that vegetation biomass were influenced mainly by the spatiotemporal characteristics of the water availability. The southeastern Yangtze River basin and the lower Pearl River basin are dominated by abundant precipitation, and vegetation is not sensitive to droughts in these regions. The northeastern Heilongjiang province, the Changbai Mountains and western Sichuan province are characterized by weak NDVI versus SPEI relations, indicating a relatively small effect of drought on vegetation; (3) The effects of annual average water balance, annual average annual precipitation, annual average effective accumulative temperature, and annual average daily sunshine hours on the NDVI versus SPEI correlation show that the annual average water balance is the key factor behind the change of vegetation vigor. It can therefore be concluded that the change of water availability is the key factor behind the change of vegetation activity and biomass. Regional precipitation or water balance was significantly related to the correlation between SPEI and NDVI. Vegetation in the regions with longer sunshine hours is more sensitive to droughts. In general, the sensitivity of grassland to droughts is the largest, followed by the sensitivity of shrubs and forests to droughts.

High energetic electron bunches from lasernear critical density layer interaction

In this paper, we report our results from interactions between sub-picosecond laser and relativistic near-critical density plasma layer. To create the near-critical density plasma layer, low density foam targets are utilized in our experiments. The foam is comprised of tri-cellulose acetate. Their average densities vary from 1 mg/cm3 to 5 mg/cm3, corresponding to full ionization densities ranging from 0.6nc to 3nc. When laser pulse is incident on the near-critical density plasma, some energetic bunches with a large quantity of charges are measured in most of the shots. The maximum charge quantity reaches to 6.1 nC/sr. Furthermore, the observed electron energy spectrum is Boltzmann-like with a wide plateau at the tail of the energy spectrum, rather than a Maxwell-like. The concept of average temperature is not available any more, and we define average effective temperature instead, namely the slope temperature. Fitting the Boltzmann-like spectrum exponentially, we find that the average effective temperature even exceeds 8 MeV at 7.51019 W/cm2, far beyond the ponderomotive limit. Aiming at analyzing the implication of physics, several two-dimensional particle-in-cell (PIC) simulations are performed. The PIC simulations indicate that the hole-boring effect and relativistic self-transparency play an important role in the electrons heating process. At the earlier stage of heating process, a short plasma channel is created by the hole-boring effect and relativistic self-transparency. The length and the width of the plasma channel are about tens of micrometers and several micrometers respectively. Around the plasma channel, there is an intensive azimuthal magnetic field. The magnitude of the azimuthal magnetic field is 100 MGs. However, the radical electrostatic field is not seen. The possible reason is that the plasma channel would be cavitated by the hole-boring effect. As a result, the electrons will experience Betatron resonance in the magnetized plasma channel. The traverse momentum of the electron would be converted into forward momentum. Assisted by the Betatron resonance, the electrons gain energies from the laser directly and efficiently. Thus, the average effective temperatures of the electron bunches are much higher than predicted by the ponderomotive scaling law. Besides, we also conducte another simulation to instigate the differences by adopting different laser polarizations. Within our expectation, the electron spectrum of the P-polarization accords well with the experimental result, while the electron spectrum of the S-polarization obviously deviates from the experimental result. It also demonstrates that the Betatron resonance heating dominates the electron acceleration process. This research paves the way to generating the highly energetic bunches with a large quantity of charges, and wound also be helpful for producing the high-bright laser bremsstrahlung sources in future.