Guidelines for precise lime management based on high-resolution soil pH, texture and SOM maps generated from proximal soil sensing data

Soil acidification is caused by natural paedogenetic processes and anthropogenic impacts but can be counteracted by regular lime application. Although sensors and applicators for variable-rate liming (VRL) exist, there are no established strategies for using these tools or helping to implement VRL in practice. Therefore, this study aimed to provide guidelines for site-specific liming based on proximal soil sensing. First, high-resolution soil maps of the liming-relevant indicators (pH, soil texture and soil organic matter content) were generated using on-the-go sensors. The soil acidity was predicted by two ion-selective antimony electrodes (RMSEpH: 0.37); the soil texture was predicted by a combination of apparent electrical resistivity measurements and natural soil-borne gamma emissions (RMSEclay: 0.046 kg kg−1); and the soil organic matter (SOM) status was predicted by a combination of red (660 nm) and near-infrared (NIR, 970 nm) optical reflection measurements (RMSESOM: 6.4 g kg−1). Second, to address the high within-field soil variability (pH varied by 2.9 units, clay content by 0.44 kg kg−1 and SOM by 5.5 g kg−1), a well-established empirical lime recommendation algorithm that represents the best management practices for liming in Germany was adapted, and the lime requirements (LRs) were determined. The generated workflow was applied to a 25.6 ha test field in north-eastern Germany, and the variable LR was compared to the conventional uniform LR. The comparison showed that under the uniform liming approach, 63% of the field would be over-fertilized by approximately 12 t of lime, 6% would receive approximately 6 t too little lime and 31% would still be adequately limed. © 2020, The Author(s)

Virtual Compton Scattering off the Nucleon in Chiral Perturbation Theory

We investigate the spin-independent part of the virtual Compton scattering (VCS) amplitude off the nucleon within the framework of chiral perturbation theory. We perform a consistent calculation to third order in external momenta according to Weinberg's power counting. With this calculation we can determine the second- and fourth-order structure-dependent coefficients of the general low-energy expansion of the spin-averaged VCS amplitude based on gauge invariance, crossing symmetry and the discrete symmetries. We discuss the kinematical regime to which our calculation can be applied and compare our expansion with the multipole expansion by Guichon, Liu and Thomas. We establish the connection of our calculation with the generalized polarizabilities of the nucleon where it is possible.Comment: 26 pages, 2 Postscript figures, RevTex using epsfi

Reproducibility of different screening classifications in ultrasonography of the newborn hip

<p>Abstract</p> <p>Background</p> <p>Ultrasonography of the hip has gained wide acceptance as a primary method for diagnosis, screening and treatment monitoring of developmental hip dysplasia in infants. The aim of the study was to examine the degree of concordance of two objective classifications of hip morphology and subjective parameters by three investigators with different levels of experience.</p> <p>Methods</p> <p>In 207 consecutive newborns (101 boys; 106 girls) the following parameters were assessed: bony roof angle (α-angle) and cartilage roof angle (β-angle) according to Graf's basic standard method, "femoral head coverage" (FHC) as described by Terjesen, shape of the bony roof and position of the cartilaginous roof. Both hips were measured twice by each investigator with a 7.5 MHz linear transducer (SONOLINE G60S^®ultrasound system, SIEMENS, Erlangen, Germany).</p> <p>Results</p> <p>Mean kappa-coefficients for the subjective parameters shape of the bony roof (0.97) and position of the cartilaginous roof (1.0) demonstrated high intra-observer reproducibility. Best results were achieved for α-angle, followed by β-angle and finally FHC. With respect to limits of agreement, inter-observer reproducibility was calculated less precisely.</p> <p>Conclusions</p> <p>Higher measurement differences were evaluated more in objective scorings. Those variations were observed by every investigator irrespective of level of experience.</p

Long term trends in ocean wind speed and wave height

Satellite altimeters have now been operational since 1985, providing global data of oceanic wind speed and wave height. In the present study a combined database covering 23 years of altimeter data from 7 separate satellites has been developed. This data has been consistently calibrated and carefully cross-validated to ensure that it represents a stable database over this extended period. In this study all the procedures carried out to form the altimeter database are described. In addition, an analysis of this database to investigate long term trends which have occurred (if there are any) in the global wind speed and wave climates over this period of time is conducted. This analysis shows that there has been a general global trend of increasing values of wind speed and, to a lesser degree, wave height, over the 23 year period. The rate of increase is greater for extreme events, as represented by monthly 90th and 99th percentile values, compared to the mean condition. These results are statistically significant and clearly demonstrate that extreme events have intensified over this period. Previous attempts to investigate global trends in oceanic wind speed and wave height relied on visual observations, point measurements or numerical modelling. Due to limitations of the data sets, these studies have either been inconclusive or indicate regionally increasing trends, consistent with the present analysis of the global oceanic wind and wave climate. Additional validation against trends from various different data sources such as oceanic buoys (point measurements) and numerical modelling is in good agreement with findings presented here. Should such trends continue in the future, it will have significant consequences for engineering design, air-sea interaction, upper-ocean mixing and potentially boost capacities of renewable energy

Faster winds and bigger waves have wide implications

The finding that oceanic wind speeds and wave heights have increased significantly over the last quarter of a century is likely to have major implications for maritime industries and climate scientists alike

Global trends in wind speed and wave height over the past 25 years

Studies of climate change typically consider measurements of temperature change over extended period of time. Climate, however, is much more than temperature. Over the oceans, changes in wind speed and the surface gravity waves, generated by such winds, play an important role. In addition to being themselves an indicator of climate change, winds and waves play important roles in the design and operation of offshore shipping and structures, as well as controlling the flux of energy from the atmosphere to the ocean and potentially upper ocean mixing. Thus, they significantly influence the mechanisms of air-sea interaction. This presentation investigates changes in global wind speed and wave height over the past 25 years, using a consistently calibrated and validated altimeter data base for this period

Changes in monthly value of ocean surface winds

Data collected from ships, remote-sensing satellites, and numerical re-analysis indicate that on average the wind speed at the ocean surface has increased in recent decades. The magnitude of reported trends vary in different studies based on dataset, data coverage, and method used. Observations of the ocean surface by satellites, namely altimeter and SSM/I, provide a reasonable long dataset with global coverage. This well calibrated and validated dataset is analysed for linear trends for regional mean time series and mean time series for each calendar month over the period of 1991-2008. The data indicate that the observed global trend is not uniformly distributed and can be linked to a signi_cant uptrend in regional average time series across equatorial regions and the Southern Ocean. When analysing trends for each calendar month, only the Southern Ocean showed a consistent increase in surface winds for at least three continuous months. Although altimeter trends are consistently stronger than trends from SSM/I, this study shows that when normalised by the global average the two datasets feature similar characteristics. For example, trends form regional average time series are typically 1.3-2.0 times the global average trend. Differences exist when looking at absolute trend estimates and therefore the true trend at the near surface remains inconclusive for some regions. The data also showed that in the month of May, one of largest uptrend was found across the North Indian Ocean which may indicate a shift in onset time of the monsoon season

Response to comment on 'Global trends in wind speed and wave height'

Response to a Wentz & Ricciardulli's comments on Young, Babanin & Zieger's 'Global trends in wind speed and wave height.' [Wentz, Frank J. & Ricciardulli, Lucrezia (2011) 'Comment on 'Global trends in wind speed and wave height,' Science, 334(6058) p. 905; and Young, I. R., Zieger, S. & Babanin, A. V. (2011) 'Global trends in wind speed and wave height,' Science, 332(6028), pp. 451-455]

Observation-based input and dissipation version of WAVEWATCH III

Measurements collected at Lake George, Australia, resulted in new insights on the processes of wind wave interaction and white-capping dissipation and consequently new parameterisations of these source terms. The new nonlinear wind input source term accounts for dependence of the growth increment on wave steepness, for airflow separation which leads to a relative reduction of the growth under extreme wind conditions, and for negative growth rate under adverse winds. The new wave breaking and whitecapping dissipation source function features two separate terms: the inherent breaking term and a cumulative dissipation term due to influences of longer waves on wave breaking of shorter waves. Another novel feature of this dissipation is the threshold in terms of spectral density: below this threshold breaking stops and whitecapping becomes zero. In such conditions dissipation due to wave interaction with water turbulence takes over, which regime is particularly relevant for decaying seas and for swell. This paper describes these source terms implemented in WAVEWATCH III and evaluates the performance against existing source terms in duration-limited simulations and against buoy measurements for windsea-dominated conditions. Results show agreement by means of growth curves and integral parameters in the simulations and hindcast. The paper also introduces wave breaking probability as model output, along with standard wind-wave metrics