Change In Spectral Index Research Articles

Pre-Harvest UV-A Supplementation in Plant Factory with Artificial Lighting Improves Growth, Photosynthesis, and Phytonutrients in Kale

UV-A (315–400 nm) is a component of solar radiation, which impacts plant physiology. Consequently, the impact was investigated of UV-A supplementation on various aspects of kale cultivation in a plant factory with artificial lighting. Three UV-A intensity treatments (5, 10, or 15 W/m2) were applied to kale plants for 5 days before harvesting. The results revealed that 5 or 10 W/m2 UV-A supplementation provided significant advantages for kale growth. The fresh weight of the kale shoots increased by over 35–50% after UV-A exposure. In particular, the 10 W/m2 UV-A exposure significantly improved the photosynthetic rate, water-use efficiency, and quantum efficiency of photosystem II (Y(II)). In addition, the treatment with UV-A positively impacted changes in leaf spectral indices, resulting in decreases in the simple ratio index (SR), the normalized phaeophytinization index (NPQI), and the normalized difference red edge index (NDRE). Furthermore, the phytonutrients in kale (Vitamin C, soluble protein, and total phenolics) were enhanced using the 10 W/m2 UV-A treatment. One notable outcome was the consistent reduction in nitrate contents across all UV-A treatment intensities. Therefore, supplementing kale cultivation with UV-A radiation was a valuable strategy for enhancing kale yield and quality in plant factory production.

Dissecting the Crab Nebula with JWST: Pulsar Wind, Dusty Filaments, and Ni/Fe Abundance Constraints on the Explosion Mechanism

We present JWST observations of the Crab Nebula, the iconic remnant of the historical SN 1054. The observations include NIRCam and MIRI imaging mosaics plus MIRI/MRS spectra that probe two select locations within the ejecta filaments. We derive a high-resolution map of dust emission and show that the grains are concentrated in the innermost, high-density filaments. These dense filaments coincide with multiple synchrotron bays around the periphery of the Crab's pulsar wind nebula (PWN). We measure synchrotron spectral index changes in small-scale features within the PWN’s torus region, including the well-known knot and wisp structures. The index variations are consistent with Doppler boosting of emission from particles with a broken power-law distribution, providing the first direct evidence that the curvature in the particle injection spectrum is tied to the acceleration mechanism at the termination shock. We detect multiple nickel and iron lines in the ejecta filaments and use photoionization models to derive nickel-to-iron abundance ratios that are a factor of 3–8 higher than the solar ratio. We also find that the previously reported order-of-magnitude higher Ni/Fe values from optical data are consistent with the lower values from JWST when we reanalyze the optical emission using updated atomic data and account for local extinction from dust. We discuss the implications of our results for understanding the nature of the explosion that produced the Crab Nebula and conclude that the observational properties are most consistent with a low-mass Fe core-collapse supernova, even though an electron-capture explosion cannot be ruled out.

Mapping and analyzing temporal variability of spectral indices in the lowland region of Far Western Nepal

Abstract Satellite imagery-based spectral indices are essential for monitoring natural resource changes and urban environments. Assessing these indices is vital for natural resource management and environmental sustainability. This study adopted geospatial techniques and satellite imagery (Landsat 5 TM and Landsat 8 OLI/TIRS) to analyze changes in key spectral indices, i.e. Normalized Difference Vegetation Index (NDVI), Normalized Difference Built-Up Index (NDBI), and Normalized Difference Water Index (NDWI) over the past three decades (1991–2022) in the low land region of Far Western Nepal. The study examined the temporal trends and intricate relationships between these indices during this time frame. The substantial changes in NDVI, NDBI, and NDWI within the study area have been quantified from 1991 to 2022. The findings revealed significantly elevated NDBI values in 1991, 2001, and 2013 compared to 2022, while NDWI and NDVI values were consistently lower in 1991,2001, and 2013 compared to 2022. Notably, a negative correlation was observed between NDVI and both NDBI and NDWI, contrasting with the positive correlation found between NDBI and NDWI. The study underscores the potential of combining these spectral indices to evaluate vegetated areas, built-up areas, and water bodies, providing valuable insights for effective land management, urban planning, environmental monitoring, and sustainable water resource management.

Effects of anthracycline chemotherapy and Kuan-Sin-Yin on the spectral indices of arterial pulse waveforms in breast cancer patients.

The vascular structure and function are potentially useful biomarkers for tumor detection. Treatment with chemotherapeutic agents may impair vascular function and increase the risk of cardiovascular disease. This study aimed to use noninvasive pulse waveform measurements to identify differences in the frequency-domain indices of the pulse waveform in breast-cancer patients following anthracycline chemotherapy between with (Group KSY) and without (Group NKSY) receiving Kuan-Sin-Yin (KSY) treatment.Radial blood pressure waveform (BPW) signals were measured noninvasively for 3 minutes in 31 patients, and the FACT-G, BFI-T, and EORTC QLQ-C30 questionnaires were administered. The following pulse indices were calculated for 10 harmonics: the amplitude proportion and its coefficient of variation, and the phase angle and its standard deviation.The changes in spectral BPW indices were more prominent in Group NKSY than in Group KSY, especially for the decreases in BPW variability indices. Scores on the FACT-G, BFI-T, and EORTC QLQ-C30 questionnaires suggested that the quality of life following chemotherapy was better in Group KSY.The identified decreases in pulse variability indices could be related to the greater impairment of regulatory activities in Group NKSY. The present findings may be meaningful in developing techniques with advantages such as being noninvasive and time-saving to evaluate the blood supply and physiological conditions following chemotherapy or other treatment strategies in cancer patients.

Hydrological and botanical diversity of a raised bog and its evaluation using in situ and remote sensing methods

Peatland vegetation requires water-logged conditions for peat-forming plant communities to survive. Changes in water regimes have been found to alter the soil environment and cause shifts in species composition. Occasionally, the spatial and chronological constraints in water table monitoring impede the correct evaluation of the status of these sensitive ecohydrological systems. Therefore, it is important to combine in situ and remote sensing methods to assess ecohydrological diversity over large areas of threatened peatland ecosystems. The present study assessed the relationship between hydrological indicators (the in situ water table fluctuations of 57 measurement wells and five study plots in the 2019 and 2020 growing seasons); botanical indicators (in situ species composition in three raised bog habitat types, namely, bog woodland, a semi-open raised bog, and an open raised bog); and spectral indices (NDVI – Normalised Difference Vegetation Index and NDWI – Normalised Difference Water Index, 2015–2020, Sentinel 2) for the evaluation of heterogeneous raised bog spatial patterns and temporal change. There were statistically significant relationships between vegetation and water table depth in different raised bog habitat types. Deeper water tables prevailed in woodland habitats (trees, green mosses, Rhododendron tomentosum) and vice versa in areas where open raised bog plants (Sphagnum) occupied the surface. Moderate relationships (r > |0.4|, p <.05) were detected between some of the botanical and hydrological indicators and spectral indices. The application of high-resolution remote sensing data may be useful for raised bog measurements, and changes in vegetation cover and related spectral indices may become hydroclimatic indicators.

Measurement of High-energy Cosmic-Ray Proton Spectrum from the ISS-CREAM Experiment

The Cosmic Ray Energetics And Mass for the International Space Station (ISS-CREAM) experiment successfully recorded data for 539 days from 2017 August to 2019 February. We report the energy spectrum of cosmic-ray protons from the ISS-CREAM experiment at energies from 1.60 × 103 to 6.55 × 105 GeV. The measured spectrum deviates from a single power law. A smoothly broken power-law fit to the data, including statistical and systematic uncertainties, shows the spectral index change at 9.0 × 103 GeV from 2.57 ± 0.03 to 2.82 ± 0.02 with a significance of greater than 3σ. This bump-like structure is consistent with a spectral softening recently reported by the balloon-borne CREAM, DAMPE, and NUCLEON, but ISS-CREAM extends measurements to higher energies.

Study of correlation between optical flux and polarization variations in BL Lac objects

ABSTRACT Polarized radiation from blazars is one key piece of evidence for synchrotron radiation at low energy, which also shows variations. We present here our results on the correlation analysis between optical flux and polarization degree (PD) variations in a sample of 11 BL Lac objects using ∼10 yr of data from the Steward Observatory. We carried out the analysis on long-term (∼several months) as well as on short-term time-scales (∼several days). On long-term time-scales, for about 85 per cent of the observing cycles, we found no correlation between optical flux and PD. On short-term time-scales, we found a total of 58 epochs with a significant correlation between optical flux and PD, where both positive and negative correlation were observed. In addition, we also found a significant correlation between optical flux and γ-ray flux variations on long-term time-scales in 11 per cent of the observing cycles. The observed PD variations in our study cannot be explained by changes in the power-law spectral index of the relativistic electrons in the jets. The shock-in-jet scenario is favoured for the correlation between optical flux and PD, whereas the anticorrelation can be explained by the presence of multizone emission regions. The varying correlated behaviour can also be explained by the enhanced optical flux caused by the newly developed radio knots in the jets and their magnetic field alignment with the large-scale jet magnetic field.

Observation of Spectral Structures in the Flux of Cosmic-Ray Protons from 50GeV to 60TeV with the Calorimetric Electron Telescope on the International Space Station.

A precise measurement of the cosmic-ray proton spectrum with the Calorimetric Electron Telescope (CALET) is presented in the energy interval from 50GeV to 60TeV, and the observation of a softening of the spectrum above 10TeV is reported. The analysis is based on the data collected during ∼6.2 years of smooth operations aboard the International Space Station and covers a broader energy range with respect to the previous proton flux measurement by CALET, with an increase of the available statistics by a factor of ∼2.2. Above a few hundred GeV we confirm our previous observation of a progressive spectral hardening with a higher significance (more than 20 sigma). In the multi-TeV region we observe a second spectral feature with a softening around 10TeV and a spectral index change from -2.6 to -2.9 consistently, within the errors, with the shape of the spectrum reported by DAMPE. We apply a simultaneous fit of the proton differential spectrum which well reproduces the gradual change of the spectral index encompassing the lower energy power-law regime and the two spectral features observed at higher energies.

Linking remote sensing and insect defoliation biology – A cross-system comparison

The success of space-based forest defoliation monitoring beyond thematic classification hinges on the ability to link units of continuous foliar change with associated units of spectral or vegetation index change across different systems. To explore this, we used multi-temporal Landsat sensor data with respect to three defoliation metrics (shoot-based estimates (%), frass biomass (kg·ha−1), and proportion of foliar loss) across three different forest systems in the United States. While shoot-based defoliation was measured in the field, the later two defoliation metrics were estimated based on the insect phenology model, BioSIM. The systems include spruce budworm (SBW, Choristoneura fumiferana C). in heterogenous mixed forests, Minnesota, jack pine budworm (JPBW, Choristoneura pinus F). in homogenous pine forests, Wisconsin, and spongy moth (SGM, Lymantria dispar dispar L). in mixed broad-leaved forests, Maryland. Our generalized annual defoliation model for budworm was poor (R2adj = 0.35, RMSE = 23.70%) due to difficulty in detecting SBW defoliation in Minnesota. Thus, individual annual JPBW shoot-based defoliation models (R2adj = 0.27 to 0.75 and RMSE = 19.16% to 11.32%) outperformed the SBW models (R2adj = 0.08 to 0.27, RMSE = 23.18% to 34.13%). Cross-system differences between rates of change in ground-based metrics of defoliation with respect to observed change in spectral index values (dVI) were significant for shoot-based estimates of percent annual defoliation for SGM vs. JPBW (p-values <1.00 × 10−4) and SGM vs. SBW (p-values < 4.60 × 10−3). However, such comparison between SGM and JPBW were not significant when either frass biomass (kg·ha−1, p-value = 0.46) or proportion of foliage loss was used (p-value = 0.67). For a given unit of defoliation, the magnitude of vegetation index change, dVI, was significantly different between SGM and JPBW for each defoliation metric used (p-values <1.00 × 10−4), but not between SGM and SBW (p-value = 0.47) or between JPBW and SBW (p-value = 0.06) when shoot-based annual defoliation metrics were used. This study is first to report that, for a given quantity of defoliation, substantial differences in both the magnitude and direction of vegetation index change exists for different defoliator systems, which currently precludes the development of a viable, unified defoliation model. However, outcomes of this research provide an important step in our understanding of these defoliator systems that may enable specific scaling of continuous defoliation at landscape levels and across defoliator systems in the future.

Supernova remnant G46.8–0.3: A new case of interaction with molecular material

Although the Galactic supernova remnant (SNR) G46.8–0.3 has been known for more than 50 yr, no specific studies of this source or its environment have been published to date. To make progress on this matter, we measured new flux densities from radio surveys and combined them with previous estimates carefully collected from the literature to create an improved and fully populated version of the integrated radio spectrum for G46.8–0.3. The resulting spectrum exhibits a featureless power-law form with an exponent α = −0.535 ± 0.012. The lack of a spectral turnover at the lowest radio frequencies, which is observable in many other SNRs, excludes the presence of abundant ionised gas either proximate to the SNR itself or along its line of sight. The analysis of local changes in the radio spectral index across G46.8–0.3 suggests a tendency to slightly steepen approximately at 1 GHz. Even if this steepening is real, it does not impact the integrated spectrum of the source. Deeper imaging of the radio structures of G46.8–0.3 and spectral maps constructed from matched raw data are needed to provide new insights into the local spectral properties of the remnant. On the basis of the spectral properties of the atomic gas, we placed the remnant at 8.7 ± 1.0 kpc and we revisited the distance to the nearby H ii region G046.495–00.241 to 7.3 ± 1.2 kpc. From evolutionary models and our distance estimate, we conclude that G46.8–0.3 is a middle-aged (~1 × 104 yr) SNR. Furthermore, we recognise several 12CO and 13CO molecular structures in the proximity of the remnant. We used combined CO-H i profiles to derive the kinematic distances to these features and characterise their physical properties. We provide compelling evidence for environmental molecular clouds physically linked to G46.8–0.3 at its centre, on its eastern edge, and towards the northern and southwestern rims on the far side of the SNR shell. Our study of the molecular matter does not confirm that the remnant is embedded in a molecular cavity as previously suggested. G46.8–0.3 shows a line-of-sight coincidence with the γ-ray source 4FGL J1918.1+1215c detected at GeV energies by the space telescope Fermi. A rough analysis based on the properties of the interstellar matter close to G46.8–0.3 indicates that the GeV γ-ray photons detected in the direction to the SNR can be plausibly attributed to hadronic collisions and/or bremsstrahlung radiation.

Suitability of the global forest cover change map to assess climatic megadisturbance impacts on remote tropical forests

The occurrence and combination of extreme meteorological events may lead to severe (megadisturbance) impacts on conserved forests and protected areas all over the world. Recent research has shown that megadisturbance impacts (after the events of hurricanes and prolonged drought) may be detected in subtropical forest cover using changes in spectral indices derived from satellite imagery. The objective of this study is to assess the impact of megadisturbance on forest types of the Alejandro de Humboldt National Park, Republic of Cuba in the 2001–2017 time-period. The Global Forest Cover Change (GFCC, available on the Global Forest Watch website) product was validated and indicated the prominence of megadisturbance for year 2016 (85% of the total disturbed area), largely associated with the Hurricane Matthew event. A robust estimator of the disturbed forest area, based on GFCC-stratified sampled verification sites, suggests that 11,110 ± 1,771 hectares of forest (~ 16% of the Park’s total area) was affected by megadisturbance between 2001 and 2017. In 2017, about 1276 hectares of forests were impacted, presumably related to a long-lasting effect of megadisturbance due to Hurricane Matthew and prolonged droughts in previous years. Four types of tropical rainforests (especially lowland rainforest and submountainous sclerophyllous rainforest on serpentinite), that cover 43% of the National Park, accounted for about 85% of the impacts by megadisturbance. The Easternmost portion of these forests should be prioritized for conservation monitoring and possibly for forest restoration strategies. This study contributes to establishing methodological guidelines for rapid environmental assessment of remote, tropical protected areas facing the impacts of extreme meteorological events and climate change.

Do radiative losses determine the characteristic emission of the blazar Mkn 421?

ABSTRACT The radiative loss interpretation for the broken power-law spectra of blazars is often questioned since the difference between the indices does not support this inference. Using the blazar Mkn 421 as a case study, we performed a detailed analysis of its characteristic photon energy where the spectral index changes significantly. We used the observations of the source by Swift–XRT from 2008 to 2019 to identify the characteristic photon energy and the corresponding spectral indices. The spectra in the energy range 0.3–10.0 keV can be well fitted by a log parabola as well as a smooth broken power law. From the smooth broken power-law spectral fit, we show that the spectral indices before and after the characteristic photon energy are strongly anticorrelated. Further, the spectral curvature measured at the characteristic photon energy indicates an anticorrelation with the low-energy spectral index while the high-energy spectral index shows a positive correlation. These findings are at variance with a simple radiative loss interpretation for the characteristic photon energy, and alternative scenarios are thus discussed. Though these scenarios are, in principle, capable of reproducing the correlation results, they deviate significantly from the observed properties.

Monitoring rice lodging grade via Sentinel-2A images based on change vector analysis

ABSTRACT Lodging stress influences the yield, quality, and mechanical harvesting ability of rice (Oryza sativa L.). It is of great significance for the quantitative and objective evaluation of rice yield loss to obtain the rice lodging distribution and grade information rapidly and nondestructively. The purpose of this paper was to establish a remote sensing monitoring method for the grade of rice lodging based on change vector analysis via Sentinel-2A images before and after lodging. Taking the lodging ratio (LR) of rice in the parcel as the characterization index, the changes in spectral reflectance and vegetation index of the rice canopy under different lodging grade stresses were analyzed. A 7-dimensional space vector was composed of a canopy spectral reflectance and vegetation index. A new angle vector was formed by the angle between each vector object and the axis of the canopy spectrum (vegetation index). Based on the difference in feature vectors before and after lodging, a lodging grade monitoring model based on rice parcels was constructed, and the accuracy of the model was verified using field observations. The results showed that the spectral reflectance of the rice canopy after lodging increased with the increase in lodging stress. The difference in vegetation index before and after lodging increased with the increase in lodging severity. Based on the change in the magnitude of the canopy spectral reflectance and its angle vector, and the vegetation index and its angle vector, the R 2 of the rice lodging model was 0.66, 0.66, 0.60, and 0.59, respectively, and the RMSE values were 21.03%, 20.37%, 22.13%, and 22.84%, respectively. Therefore, the accuracy of the model constructed using the vegetation index was the highest. The canopy spectral reflectance and difference in the vegetation index of rice changed regularly with lodging grade stress. The model based on the change magnitude of the vegetation index could effectively realize remote sensing monitoring of the grade of rice lodging in Wuchang.

Analysis of the solar cosmic-ray spectrum during ground-level enhancements

In this work, we analyze the spectrum of solar cosmic rays flux during ground-level enhancements using the pair of lead-free and standard neutron monitors in the South Pole station. Using both monitor data, effects due to anisotropy are considerably reduced. We assume a power-law form for the solar particle spectrum at the top of the atmosphere. The spectral index was computed during all events for which data were available, regardless of the duration or the intensity of the GLE. Seventeen events were analyzed. In this paper, we show the efficiency of the method used, as well as a clear tendency of the spectral index behavior to the ratio between the observed increases in both monitors. It is also shown that the method can be used to calculate the solar cosmic ray spectrum at any required stage of the event. Our results show that the spectral index estimation depends on the choice of the yield function. For the three yield functions used in the analysis, the spectral index changes by about 10%.

Correlation between optical flux and polarization variations in flat-spectrum radio quasars on diverse time-scales

ABSTRACT Study of the polarization behaviour in blazars is a powerful tool to discern the role of the magnetic field in the variable emission process in their relativistic jets. We present here the results of our systematic investigation on the correlation between optical flux and polarization variations for eight flat-spectrum radio quasars on various time-scales using data from the Steward Observatory that covers a period of ∼10 years. On long time-scales (∼several months), from a total of 79 observing cycles, we found a significant positive correlation between optical flux and optical polarization degree (PD) in 34 observing cycles, a negative correlation in three cycles, and no correlation in 42 cycles. On short time-scales (∼few days), in 47 out of a total of 55 epochs we found a positive correlation between optical flux and PD, while for the remaining eight epochs an anticorrelation was detected between the two quantities. Moreover, we noticed a significant positive correlation between optical and γ-ray fluxes in 14 epochs, and a negative correlation between the two in one epoch. While the observed optical flux changes fit the shock-in-jet model well, the observed changes in PD are not explainable by changes in the power-law spectral index of the relativistic electrons in the jet. Instead, the observed varied correlations between optical flux and PD could be due to multizone emission regions or the enhanced flux coinciding with the emergence of a new emission knot with its magnetic field either aligned or misaligned with the large-scale magnetic field.

Time-dependent Treatment of Cosmic-ray Spectral Steepening Due to Turbulence Driving

Abstract Cosmic-ray acceleration at non-relativistic shocks relies on scattering by turbulence that the cosmic rays drive upstream of the shock. We explore the rate of energy transfer from cosmic rays to non-resonant Bell modes and the spectral softening it implies. Accounting for the finite time available for turbulence driving at supernova-remnant shocks yields a smaller spectral impact than found earlier with steady-state considerations. Generally, for diffusion scaling with the Bohm rate by a factor η, the change in spectral index is at most η divided by the Alfvénic Mach number of the thermal sub-shock. For M A ≲ 50 it is well below this limit. Only for very fast shocks and very efficient cosmic-ray acceleration can the change in spectral index reach 0.1. For standard SNR parameters, it is negligible. Independent confirmation is derived by considering the synchrotron energy losses of electrons: if intense nonthermal multi-keV emission is produced, the energy loss, and hence the spectral steepening, is very small for hadronic cosmic rays that produce TeV-band gamma-ray emission.

The ultra-steep diffuse radio emission observed in the cool-core cluster RX J1720.1+2638 with LOFAR at 54 MHz

ABSTRACT Diffuse radio emission at the centre of galaxy clusters has been observed both in merging clusters on scales of Mpc, called giant radio haloes, and in relaxed systems with a cool-core on smaller scales, named mini haloes. Giant radio haloes and mini haloes are thought to be distinct classes of sources. However, recent observations have revealed the presence of diffuse radio emission on Mpc scales in clusters that do not show strong dynamical activity. RX J1720.1+2638 is a cool-core cluster, presenting both a bright central mini halo and a fainter diffuse, steep-spectrum emission extending beyond the cluster core that resembles giant radio halo emission. In this paper, we present new observations performed with the LOw Frequency ARray Low Band Antennas (LBA) at 54 MHz. These observations, combined with data at higher frequencies, allow us to constrain the spectral properties of the radio emission. The large-scale emission presents an ultrasteep spectrum with $\alpha _{54}^{144}\sim 3.2$. The radio emission inside and outside the cluster core have strictly different properties, as there is a net change in spectral index and they follow different radio-X-ray surface brightness correlations. We argue that the large-scale diffuse emission is generated by particles re-acceleration after a minor merger. While for the central mini halo, we suggest that it could be generated by secondary electrons and positrons from hadronic interactions of relativistic nuclei with the dense cool-core gas, as an alternative to re-acceleration models.

Inflation with R (αβ) terms in the Palatini formulation

We study inflation with the most general non-degenerate gravitational action that depends on the symmetric part of the Ricci tensor coupled to a scalar field in the Palatini formulation of gravity. We use field redefinitions to shift the effect of the Ricci terms from gravity to the scalar field, and apply the result to slow-roll inflation.As examples, we consider actions quadratic and cubic in the Ricci tensor. In the quadratic case the results are similar to the case R + α R 2 that has been studied earlier: the tensor-to-scalar ratio r can be suppressed by an arbitrary amount, while the scalar spectrum is unaffected. In the cubic case, r can be suppressed by at most a factor of 2/9, and the change in the scalar spectral index n s can be large.

Fruit Tree Identification Based on Multi-source Remote Sensing Image Data—Taking Pomegranate Tree as an Example

In recent years, the development of remote sensing technology systems with medium-high spatial, temporal and spectral resolution is very fast. Remote sensing technology has been widely used in the extraction of feature elements and has achieved good results. If we could identify tree species accurately use remote sensing technology, it will be convenient and efficient to obtain the area of single fruit planting in the investigation of large-scale and multi-variety agricultural products. Then providing guidance for the planning of fruit tree and avoiding expanding planting area blindly according to price trends to bring planting economic benefits. At present, the tree species structure in the fruit growing area is complex, and it is difficult to accurately distinguish a single tree species. The existing extraction method to pomegranate cultivation area is poor effective. Therefore, based on the multi-source remote sensing image and field data, we should preprocess the remote sensing image firstly, then we do the band difference, ratio analysis, spectral index calculation spectral index change tracking, image composite and identification methods co-processing. In the last step we analyse the differences of NDVI values and spectral characteristics of remote sensing images of different tree species in different periods, then we can recognize and extract the pomegranate in fruit tree planting area. The results of the experiment indicate that the method can effectively extract the distribution information of pomegranate trees in complex areas where planting information is available. Thus it can be extended to other crop identification research, which can provide a good reference for the development of precision agriculture and intelligent agriculture management.

Parker Solar Probe Observations of Alfvénic Waves and Ion-cyclotron Waves in a Small-scale Flux Rope

Abstract Small-scale flux ropes (SFRs) are common in the interplanetary environment. However, previous identification procedures generally discard SFRs with medium and high Alfvénicity, which are thought to be Alfvénic waves or Alfvénic structures. This paper first identifies an SFR event with medium Alfvénicity in the inner heliosphere (at ∼0.2 au) using Parker Solar Probe measurements. We find Alfvénic waves that arise inside SFR based on high correlations between the magnetic field and velocity fluctuations. We also observe quasi-monochromatic electromagnetic waves with frequencies f that are usually larger than the local proton cyclotron frequency at the leading and trailing edges of this SFR. These waves are well explained by the outward-propagating ion-cyclotron waves, which have wave frequencies ∼0.03–0.3 Hz and wavelengths ∼60–2000 km in the plasma frame. Moreover, we show that the power spectral density of the magnetic field in SFR middle region follows the power-law distribution, where the spectral index changes from −1.5 (f ≲ 1 Hz) to −3.3 (f ≳ 1 Hz). These findings would motivate developing an automated program to identify SFRs with medium and high Alfvénicity from Alfvénic waves/structures.