The relationship between frost heave and downslope soil movement: field measurements in the Japanese Alps

Unmanned aerial vehicles (UAVs) equipped with multispectral sensors present an opportunity to monitor vegetation with on-demand high spatial and temporal resolution. In this study, we use multispectral imagery from quadcopter UAVs to monitor the progression of a water manipulation experiment on a common shrub, Baccharis pilularis (coyote brush), at the Blue Oak Ranch Reserve (BORR) near San Jose, California. We recorded multispectral data from the plants at several altitudes with nearly hourly intervals to explore the relationship between two common spectral indices, NDVI and NDRE, and plant water content and water potential, as physiological metrics of plant water status, across a gradient of water deficit. An examination of the spatial and temporal thresholds at which water limitations were most detectable revealed that the best separation between levels of water deficit were at higher resolution (lower flying height), and in the morning (NDVI) and early morning (NDRE). We found that both measures were able to identify moisture deficit in plants and distinguish them from control and watered plants; however, NDVI was better able to distinguish between treatments than NDRE and was more positively correlated with field measurements of plant water content than NDRE. Finally, we explored how relationships between spectral indices and water status changed when the imagery was scaled to courser resolutions provided by satellite-based imagery (PlanetScope) and found that PlanetScope data was able to capture the overall trend in treatments but was not able to capture subtle changes in water content. These kinds of experiments that evaluate the relationship between direct field measurements and UAV camera sensitivity are needed to enable translation of field-based physiology measurements to landscape or regional scales.

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From Bulbous Bow to Free-Surface Shock Wave—Trends of 20 Years’ Research on Ship Waves at the Tokyo University Tank

Journal of Ship Research ◽

10.5957/jsr.1981.25.3.147 ◽

1981 ◽

Vol 25 (03) ◽

pp. 147-180

Author(s):

Takao Inui

Keyword(s):

Shock Wave ◽

Free Surface ◽

Field Measurements ◽

Wave Pattern ◽

Ship Waves ◽

Second Stage ◽

Initial Stage ◽

Man And Nature ◽

Bulbous Bow ◽

The Relationship

Trends of 20 years' research on ship waves at the Tokyo University Tank since 1960 are briefly sketched. Stress is focused on the importance of dialogues between man and nature. The process of these dialogues is exemplified by some typical cases, including the development of bulbous bows and the finding of free-surface shock waves. Wave-pattern pictures are shown to be indispensable for the initial stage of the di alogues, while wave contours and velocity-field measurements serve well in the second stage. The current wave analysis and wake survey may be the third. The relationship between "wavebreaking" and the "free-surface shock wave" is also discussed.

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Nonlinear Relationship Between the Yield of Solar-Induced Chlorophyll Fluorescence and Photosynthetic Efficiency in Senescent Crops

Remote Sensing ◽

10.3390/rs12091518 ◽

2020 ◽

Vol 12 (9) ◽

pp. 1518

Author(s):

Leizhen Liu ◽

Wenhui Zhao ◽

Qiu Shen ◽

Jianjun Wu ◽

Yanguo Teng ◽

...

Keyword(s):

Chlorophyll Fluorescence ◽

Imaging System ◽

Field Measurements ◽

Maximum Efficiency ◽

Operating Efficiency ◽

Nonlinear Relationship ◽

Diurnal Changes ◽

Psii Photochemistry ◽

Leaf Level ◽

The Relationship

It has been demonstrated that solar-induced chlorophyll fluorescence (SIF) is linearly related to the primary production of photosynthesis (GPP) in various ecosystems. However, it is unknown whether such linear relationships have been established in senescent crops. SIF and GPP can be expressed as the products of absorbed photosynthetically active radiation (APAR) with the SIF yield and photosystem II (PSII) operating efficiency, respectively. Thus, the relationship between SIF and GPP can be represented by the relationship between the SIF yield and PSII operating efficiency when the APAR has the same value. Therefore, we analyzed the relationship between the SIF yield and the PSII operating efficiency to address the abovementioned question. Here, diurnal measurements of the canopy SIF (760 nm, F760) of soybean and sweet potato were manually measured and used to calculate the SIF yield. The PSII operating efficiency was calculated from measurements of the chlorophyll fluorescence at the leaf level using the FluorImager chlorophyll fluorescence imaging system. Meanwhile, field measurements of the gas exchange and other physiological parameters were also performed using commercial-grade devices. The results showed that the SIF yield was not linearly related to the PSII operating efficiency at the diurnal scale, reflecting the nonlinear relationship between SIF and GPP. This nonlinear relationship mainly resulted from the heterogeneity and diurnal dynamics of the PSII operating efficiency and from the intrinsic diurnal changes in the maximum efficiency of the PSII photochemistry and the proportion of opened PSII centers. Intensifying respiration was another factor that complicated the response of photosynthesis to the variation in environmental conditions and negatively impacted the relationship between the SIF yield and the PSII operating efficiency. The nonlinear relationship between the SIF yield and PSII efficiency might yield errors in the estimation of GPP using the SIF measurements of senescent crops.

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GC×GC measurements of C<sub>7</sub>-C<sub>11</sub> aromatic and n-alkane hydrocarbons on Crete, in air from Eastern Europe during the MINOS campaign

Atmospheric Chemistry and Physics ◽

10.5194/acp-3-1461-2003 ◽

2003 ◽

Vol 3 (5) ◽

pp. 1461-1475 ◽

Cited By ~ 22

Author(s):

X. Xu ◽

C. Williams ◽

H. Plass-Dülmer ◽

H. Berresheim ◽

G. Salisbury ◽

...

Keyword(s):

Rate Constants ◽

Field Measurements ◽

Early Morning ◽

Reaction Model ◽

Sequential Reaction ◽

Related Data ◽

Mixing Ratios ◽

Ground Station ◽

The Mean ◽

The Relationship

Abstract. During the Mediterranean Intensive Oxidant Study (MINOS) campaign in August 2001 gas-phase organic compounds were measured using comprehensive two-dimensional gas chromatography (GCxGC) at the Finokalia ground station, Crete. In this paper, C7-C11 aromatic and n-alkane measurements are presented and interpreted. The mean mixing ratios of the hydrocarbons varied from 1±1 pptv (i-propylbenzene) to 43±36 pptv (toluene). The observed mixing ratios showed strong day-to-day variations and generally higher levels during the first half of the campaign. Mean diel profiles showed maxima at local midnight and late morning, and minima in the early morning and evening. Results from analysis using a simplified box model suggest that both the chemical sink (i.e. reaction with OH) and the variability of source strengths were the causes of the observed variations in hydrocarbon mixing ratios. The logarithms of hydrocarbon concentrations were negatively correlated with the OH concentrations integral over a day prior to the hydrocarbon measurements. Slopes of the regression lines derived from these correlations for different compounds are compared with literature rate constants for their reactions with OH. The slopes for most compounds agree reasonably well with the literature rate constants. A sequential reaction model has been applied to the interpretation of the relationship between ethylbenzene and two of its potential products, i.e. acetophenone and benzeneacetaldehyde. The model can explain the good correlation observed between [acetophenone]/[ethylbenzene] and [benzeneacetaldehyde]/[ethylbenzene]. The model results and field measurements suggest that the reactivity of benzeneacetaldehyde may lie between those of acetophenone and ethylbenzene and that the ratio between yields of acetophenone and benzeneacetaldehyde may be up to 28:1. Photochemical ages of trace gases sampled at Finokalia during the campaign are estimated using the sequential reaction model and related data. They lie in the range of about 0.5-2.5 days.

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Density-dependent calibration of multisensor capacitance probes in coarse soil

Canadian Journal of Soil Science ◽

10.4141/cjss-2015-021 ◽

2015 ◽

Vol 95 (4) ◽

pp. 331-336 ◽

Cited By ~ 3

Author(s):

Julie D. Zettl ◽

Mingbin Huang ◽

S. Lee Barbour ◽

Bing C. Si

Keyword(s):

Water Content ◽

Soil Water ◽

Field Measurements ◽

Water Dynamics ◽

Laboratory Measurements ◽

Calibration Equation ◽

Density Dependent ◽

Capacitance Probe ◽

The Relationship ◽

Coarse Soil

Zettl, J. D., Huang, M., Barbour, S. L. and Si, B. C. 2015. Density-dependent calibration of multisensor capacitance probes in coarse soil. Can. J. Soil Sci. 95: 331–336. Coarse-textured reconstructed soils are utilized extensively in the reclamation of mining waste. Accurate and continuous sensing of soil water content is required to understand soil water dynamics and evaluate the hydraulic characteristics of these soils. The EnviroSCAN (Sentek Pty. Ltd, Australia) is a semi-permanent multisensor capacitance probe (MCP) capable of continuous measurement of volumetric water content (θv) and has been used to monitor reclamation soil cover performance. Calibration of these probes is required to improve the accuracy of field measurements. In this study, field and laboratory measurements were undertaken over a range of water contents and bulk densities to refine the relationship between θvand scaled frequency (SF) measured by the MCP. The manufacturer's calibration equation tended to underestimate θvunder wet conditions (θv>0.35 cm3cm–3). Our experimental data showed that bulk density (ρb) did affect the MCP calibration and consequently a new calibration equation that includes the effect of ρbis developed using laboratory measurements and validated using field measurements. This equation provided the highest degree of correlation and the smallest standard deviation of prediction to measured values of θvfor laboratory and field measurements, respectively. This calibration improves the application of the EnviroSCAN for coarse-textured soils such as those utilized in this study.

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Understanding atmospheric peroxyformic acid chemistry: observation, modeling and implication

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-15-2055-2015 ◽

2015 ◽

Vol 15 (2) ◽

pp. 2055-2084 ◽

Cited By ~ 2

Author(s):

H. Liang ◽

Z. M. Chen ◽

D. Huang ◽

Q. Q. Wu ◽

L. B. Huang

Keyword(s):

Field Measurements ◽

Observation Data ◽

Strong Positive Correlation ◽

Peroxyacetic Acid ◽

Hydroperoxyl Radical ◽

Sources And Sinks ◽

The Impact ◽

First Time ◽

The Relationship ◽

Peroxyformic Acid

Abstract. The existence and importance of peroxyformic acid (PFA) in the atmosphere has been under controversy. We present here, for the first time, the observation data for PFA from four field measurements carried out in China. These data provided powerful evidence that PFA can stay in the atmosphere, typically in dozens of pptv level. The relationship between PFA and other detected peroxides was examined. The results showed that PFA had a strong positive correlation with its homolog, peroxyacetic acid, due to their similar sources and sinks. Through an evaluation of PFA production and removal rates, we proposed that the reactions between peroxyformyl radical (HC(O)O2) and formaldehyde or the hydroperoxyl radical (HO2) were likely to be the major source and degradation into formic acid (FA) was likely to be the major sink for PFA. Based on a box model evaluation, we proposed that the HC(O)O2 and PFA chemistry was a major source for FA under low NOx conditions. Furthermore, it is found that the impact of the HC(O)O2 and PFA chemistry on radical cycling was dependent on the yield of HC(O)O2 radical from HC(O) + O2 reaction. When this yield exceeded 50%, the HC(O)O2 and PFA chemistry should not be neglected for calculating the radical budget. To make clear the exact importance of HC(O)O2 and PFA chemistry in the atmosphere, further kinetic, field and modeling studies are required.

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Remotely Sensed Water Limitation in Vegetation: Insights from an Experiment with Unmanned Aerial Vehicles (UAVs)

Remote Sensing ◽

10.3390/rs11161853 ◽

2019 ◽

Vol 11 (16) ◽

pp. 1853 ◽

Cited By ~ 10

Author(s):

Kelly Easterday ◽

Chippie Kislik ◽

Todd Dawson ◽

Sean Hogan ◽

Maggi Kelly

Keyword(s):

Unmanned Aerial Vehicles ◽

Water Content ◽

Water Deficit ◽

Water Status ◽

Field Measurements ◽

Leaf Water Content ◽

Multispectral Imagery ◽

Spectral Indices ◽

Aerial Vehicles ◽

The Relationship

Unmanned aerial vehicles (UAVs) equipped with multispectral sensors present an opportunity to monitor vegetation with on-demand high spatial and temporal resolution. In this study we use multispectral imagery from quadcopter UAVs to monitor the progression of a water manipulation experiment on a common shrub, Baccharis pilularis (coyote brush) at the Blue Oak Ranch Reserve (BORR) ~20 km east of San Jose, California. We recorded multispectral imagery at several altitudes with nearly hourly intervals to explore the relationship between two common spectral indices, NDVI (normalized difference vegetation index) and NDRE (normalized difference red edge index), leaf water content and water potential as physiological metrics of plant water status, across a gradient of water deficit. An examination of the spatial and temporal thresholds at which water limitations were most detectable revealed that the best separation between levels of water deficit were at higher resolution (lower flying height), and in the morning (NDVI) and early morning (NDRE). We found that both measures were able to identify moisture deficit across treatments; however, NDVI was better able to distinguish between treatments than NDRE and was more positively correlated with field measurements of leaf water content. Finally, we explored how relationships between spectral indices and water status changed when the imagery was scaled to courser resolutions provided by satellite-based imagery (PlanetScope).We found that PlanetScope data was able to capture the overall trend in treatments but unable to capture subtle changes in water content. These kinds of experiments that evaluate the relationship between direct field measurements and UAV camera sensitivity are needed to enable translation of field-based physiology measurements to landscape or regional scales.

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Effect of Rainfall Infiltration on Loess Pitted Courtyard Cave Dwellings Stability

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.430-432.1992 ◽

2012 ◽

Vol 430-432 ◽

pp. 1992-1995 ◽

Cited By ~ 5

Author(s):

Jia Ming Han ◽

San Qing Su

Keyword(s):

Water Content ◽

Safety Factor ◽

Triaxial Test ◽

Field Measurements ◽

Surrounding Rock ◽

Rainfall Infiltration ◽

Mechanical Parameter ◽

Different Depths ◽

Definition Of ◽

The Relationship

Baishe villagers have inhabited loess pitted courtyard cave dwelling for hundreds of years in Sanyuan County of China.The sizes of local cave dwellings are mastered by field measurements, and variational regularity is summarized of average annual and monthly rainfall. By the soil routine and triaxial test, the physical and mechanical parameter is acquired with loess samples in different water content.At the same time, based on the literature datas, the relationship is established between rainfall and water content. Then, the definition of safety factor is given for loess cave dwellings in different depths, making use of the expressions of the surrounding rock loop stress and the Mohr - Coulomb intensity criterion. In the end,the variation of stability of loess cave dwelling could be analysed under different rainfall.

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