29 research outputs found
Comment on ‘Examining the variation of soil moisture from cosmic‑ray neutron probes footprint: experimental results from a COSMOS‑UK site’ by Howells, O.D., Petropoulos, G.P., et al., Environ Earth Sci 82, 41 (2023)
The published article by Howells et al. (2023) attempts to empirically derive the lateral footprint for a single cosmic-ray neutron sensor (CRNS), which is part of the COSMOS-UK network (Evans et al. 2016). The main result is the “true” footprint to be 50 m in radius, substantially smaller than previously published estimates. Their conclusion contradicts more than 15 peer-reviewed studies and more than a decade of research on the subject conducted by various international research groups, and thus, it would be considered as a ground-breaking finding if the methods were scientifically sound. However, the methods and arguments presented by the authors have major errors and the presented conclusions are consequently wrong
Triangulation network of 1929-1944 of the first 1:500 urban map of València
[EN] Triangulation is a surveying method on which earlier maps made were based. Although the origins
of the method can be traced back to the 16th century, it is still used today, with minor changes, to
adjust networks observed with modern geodetic techniques. In this paper we present the geodetic
survey work that was carried out for the primary triangulation network of the first 1:500 urban map of
the city of València (Spain). It spanned from 1929 to 1944 and resulted in 421 maps covering about
174 square kilometres. We focus on four key elements to define the geometric framework of a map:
(1) the geodetic network, (2) the cartographic projection, (3) the baseline measurements, and (4)
the primary triangulation. The paper is based on the interpretation of original documents and
field books recovered from the archives of the València City Council. In order to check the
accuracy and consistency of the survey work, we recomputed all calculations directly from the
field data, following the mathematical procedures of the time. We obtained a set of
transformation parameters to convert the coordinates of 1929 to current coordinates based on
the European Terrestrial Reference System of 1989 (ETRS89). Results showed that the 1929
primary triangulation angles and coordinates are accurate to 8 s of arc and 35 cm respectively,
and that the coordinates transform well into the current reference system with average residuals
of 26 cm across nine control points, demonstrating the high quality of the 1929 work.Villar-Cano, M.; Marqués-Mateu, Á.; Jiménez-Martínez, MJ. (2020). Triangulation network of 1929-1944 of the first 1:500 urban map of València. Survey Review (Online). 52(373):317-329. https://doi.org/10.1080/00396265.2018.1564599S31732952373Bitelli, G., Cremonini, S., & Gatta, G. (2014). Cartographic heritage: Toward unconventional methods for quantitative analysis of pre-geodetic maps. Journal of Cultural Heritage, 15(2), 183-195. doi:10.1016/j.culher.2013.04.003Blachut, T. J., Chrzanowski, A., & Saastamoinen, J. H. (1979). Urban Surveying and Mapping. doi:10.1007/978-1-4612-6145-2Brinker, R. C., & Minnick, R. (Eds.). (1987). The Surveying Handbook. doi:10.1007/978-1-4757-1188-2Gatta, G. 2010. Valorizzazione di cartografia storica attraverso moderne tecniche geomatiche: recupero metrico, elaborazione e consultazione in ambiente digitale [Valuation of historic cartography using modern geomatics techniques: metric recovering, making and use in digital environment]. Doctoral thesis. Bologna: Universitá di Bologna. 295 pages. (In Italian).Gorse, C., Johnston, D., & Pritchard, M. (2012). A Dictionary of Construction, Surveying and Civil Engineering. doi:10.1093/acref/9780199534463.001.0001Hotine, M. (1939). THE RE-TRIANGULATION OF GREAT BRITAIN IV—BASE MEASUREMENT. Empire Survey Review, 5(34), 211-225. doi:10.1179/sre.1939.5.34.211Kahmen, H., & Faig, W. (1988). Surveying. doi:10.1515/9783110845716Leick, A., Rapoport, L., & Tatarnikov, D. (2015). GPS Satellite Surveying. doi:10.1002/9781119018612Murdin, P. (2009). Full Meridian of Glory. doi:10.1007/978-0-387-75534-2Schofield, W., & Breach, M. (2007). Engineering Surveying. doi:10.1201/b12847Seeber, G. (2003). Satellite Geodesy. doi:10.1515/9783110200089Snyder, J. P. (1987). Map projections: A working manual. Professional Paper. doi:10.3133/pp139
Tables de logarithmes à sept décimales : pour les nombres depuis 1 jusqu'a 108.000 : et pour les fonctions trigonométriques de dix en dix secondes
Éd. stéréotype, rev. et corr., nouveau tirag
Improving calibration and validation of cosmic-ray neutron sensors in the light of spatial sensitivity
In the last few years the method of
cosmic-ray neutron sensing (CRNS) has gained popularity among hydrologists,
physicists, and land-surface modelers. The sensor provides continuous soil
moisture data, averaged over several hectares and tens of decimeters in
depth. However, the signal still may contain unidentified features of
hydrological processes, and many calibration datasets are often required in
order to find reliable relations between neutron intensity and water
dynamics. Recent insights into environmental neutrons accurately described
the spatial sensitivity of the sensor and thus allowed one to quantify the
contribution of individual sample locations to the CRNS signal. Consequently,
data points of calibration and validation datasets are suggested to be
averaged using a more physically based weighting approach. In this work, a
revised sensitivity function is used to calculate weighted averages of point
data. The function is different from the simple exponential convention by the
extraordinary sensitivity to the first few meters around the probe, and by
dependencies on air pressure, air humidity, soil moisture, and vegetation.
The approach is extensively tested at six distinct monitoring sites: two
sites with multiple calibration datasets and four sites with continuous time
series datasets. In all cases, the revised averaging method improved the
performance of the CRNS products. The revised approach further helped to
reveal hidden hydrological processes which otherwise remained unexplained in
the data or were lost in the process of overcalibration. The presented
weighting approach increases the overall accuracy of CRNS products and will
have an impact on all their applications in agriculture, hydrology, and
modeling
An interdisciplinary study of weathering effects in ordinary chondrites from the Acfer region, Algeria
Weathering effects on meteorite finds from the Acfer region were studied by various analytical techniques and in dependence on the depth of sampling. In thin sections of weathered meteorites, weathering effects usually decrease from the outside to the interior of the meteorite. The results of evolved gas analysis indicate that variation in weathering between surface and core is not significant in respect to the formation of Fe-oxyhydroxides. The secondary alteration effects in the noble gases are distributed unevenly throughout the specimens, as seen in the nonsystematic differences observed for the heavy noble gases. Chemical analyses show significant enrichment of Ba and Sr in the outer parts of the weathered samples due to element contamination through aqueous solution. Iron, Ni, and Co are partly flushed from the system as the metal oxidation proceeds. Oxygen isotopes show increases in delta(sup 18)O and delta(sup 17)O with increasing terrestrial age. For a set of H3 chondrites, the degree of weathering determined from the water content was correlated with terrestrial ages and is discussed with respect to possible weathering mechanisms