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Crawford et al. (Boundary-Layer Meteorol 66:237–245, 1993) showed that the time average is inappropriate for airborne eddy-covariance flux calculations. The aircraft’s ground speed through a turbulent field is not constant. One reason can be a correlation with vertical air motion, so that some types of structures are sampled more densely than others. To avoid this, the time-sampled data are adjusted for the varying ground speed so that the modified estimates are equivalent to spatially-sampled data. A comparison of sensible heat-flux calculations using temporal and spatial averaging methods is presented and discussed. Data of the airborne measurement systems $\hbox {M}^2\hbox {AV}$ , Helipod and Dornier 128-6 are used for the analysis. These systems vary in size, weight and aerodynamic characteristics, since the $\hbox {M}^2\hbox {AV}$ is a small unmanned aerial vehicle (UAV), the Helipod a helicopter-borne turbulence probe and the Dornier 128-6 a manned research aircraft. The systematic bias anticipated in covariance computations due to speed variations was neither found when averaging over Dornier, Helipod nor UAV flight legs. However, the random differences between spatial and temporal averaging fluxes were found to be up to 30 % on the individual flight legs. 相似文献
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Sabrina Kumschick Stefan Fronzek Martin H. Entling Wolfgang Nentwig 《Climatic change》2011,109(3-4):319-329
Numerous species are expanding their ranges towards the North Pole, a pattern that is usually explained with climate change. However, few studies have actually tested the potential role of climate in such range expansions. Here, we studied the wasp spider Argiope bruennichi, which has multiplied its range in Central and Northern Europe during the 20th century and is still spreading. Using current and historical climate data, we analysed whether this spread can be explained by climate warming, increasing cold tolerance or if it is unrelated to temperature. Spatial partial regression showed that the spread of A. bruennichi into formerly cooler areas is independent of spatial autocorrelation, indicating that it is driven by temperature. Some aspects of the spread, as e.g. the patchy distribution at the beginning of the century are likely to be relicts of climate fluctuations before our study period. From the middle of the 20th century until the 1980s, A. bruennichi was recorded from gradually cooler climates, while temperature was relatively constant. This indicates that A. bruennichi either increased its cold tolerance or that the spread continued with a time lag following an earlier warming event, due to dispersal limitation. In the last two decades, temperature rose sharply. The temperatures at which A. bruennichi was newly recorded increased as well, indicating that the spider is dispersal limited and that the spread will continue even in the absence of further climate warming. 相似文献
35.
J. Juan Chanes-Martínez Mario González-Escobar Francisco Suárez-Vidal Clemente G. Gallardo-Mata 《Pure and Applied Geophysics》2014,171(7):1107-1127
A structural study in the SW section of the Colorado River delta using seismic reflection data is presented. The study area is located along the Cerro Prieto transform fault, which extends from the northern Gulf of California through the Mexicali Valley and is an active fault within the Pacific-North American plate boundary zone. The research was supported by a database of five seismic profiles with a total length of 215 km, collected in the early 80’s by Petróleos Mexicanos. The results show a high density of faults, most of which are buried by sediments. Within the Cerro Prieto fault zone, several faults were identified, such as: Palmas, Mesa, and Pangas Viejas, until now unknown. In addition, even though the Indiviso fault was investigated and superficially identify prior to this work, herein mapped at depth. West of the Cerro Prieto fault zone lies the Las Tinajas basin, bound by the Dunas and Saldaña faults and by the Montague basin to the southeast. The deformation zone along the plate boundary is 18-km-wide, stretching from the Cerro Prieto fault in the east to the Pangas Viejas fault in the west. The orientations of the faults are NW–SE, and if projected from the southern side of the Sierra Cucapah southward, the faults tend to join the Cerro Prieto fault. In the Las Tinajas basin, the acoustic basement is deeper than 5,000 m. Some of the largest vertical displacements generated by the 2010 7.2-Mw El Mayor-Cucapah earthquake occurred southeast of the epicenter and coincided with the location of the Pangas Viejas Fault, which is buried by sediments. Before this event, seismic activity was very low, and no structures were known in the area. In this paper, we demonstrate that there are at least seven major faults that may now pose a high seismic hazard. 相似文献
36.
Fazzito Sabrina Y. Rapalini Augusto E. Cortés José M. Terrizzano Carla M. 《International Journal of Earth Sciences》2017,106(2):631-657
International Journal of Earth Sciences - Palaeomagnetic data from poorly consolidated to non-consolidated late Cenozoic sediments along the central segment of the active El Tigre Fault... 相似文献
37.
Small rookeries are rarely evaluated for marine turtles worldwide. Two species of sea turtles (Hawksbill, Eretmochelys imbricata; Leatherback, Dermochelys coriacea) nest on five main beaches of the northeast coast of the Paria Gulf in Venezuela. Population trends using generalized linear models at this rookery were assessed and compared with other small rookeries. Both species showed significant negative nesting trends: Nesting by critically endangered hawksbills decreased over nine seasons 2009–2017 (64–142 nests per year, General Linear Model Slope Value = ?0.061; data pooled for five beaches); similarly, vulnerable leatherback nests decreased across the same period in the main beach Los Garzos (0–69 nests/year; GLMSV = ?0.34). Besides human and natural predation of the nests, no significant environmental impacts affect the beaches except probably on Obispo Isthmus where a gas pipeline installation interrupted the nesting activity in 2014. Observed changes to the nesting trends in these small rookeries have a collective impact on broader conservation concerns for sea turtles in the region. 相似文献
38.
Tanajura Clemente A. S. Mignac Davi de Santana Alex N. Costa Filipe B. Lima Leonardo N. Belyaev Konstantin P. Zhu Jiang 《Ocean Dynamics》2020,70(1):115-138
Ocean Dynamics - The Oceanographic Modeling and Observation Network (REMO) focuses on scientific and technological development of operational oceanography in Brazil considering both numerical... 相似文献
39.
Carlos A. Vasquez Facundo F. Sapienza Agustín Somacal Sabrina Y. Fazzito 《Studia Geophysica et Geodaetica》2018,62(2):339-351
A phenomenological model based on a linear relationship between the magnetic coercivity field and the reciprocal of the grain diameter is applied to explain the anhysteretic remanent magnetization (ARM) imparted to artificial samples with different concentrations of a very well characterized magnetite powder. By analyses of scanning electron microscopy images, the spherically shaped single domain synthetic magnetite is found to follow a lognormal grain size distribution with ~86 nm of mean diameter. The proposed model, fitted to ARM measurements up to a peak alternating field of 100 mT, yields a very good agreement. The coercivity behaviour predicted by micromagnetism theory disagrees with the experimental results of this work. A likely explanation for the discrepancy is that the magnetite particles, which consist of a mixture of grains in coherent rotation and curling modes, produce similar observations as domain processes. 相似文献
40.
Clette Frédéric Lefèvre Laure Bechet Sabrina Ramelli Renzo Cagnotti Marco 《Solar physics》2021,296(9):1-16
Solar Physics - The final version (V.19) of the total solar irradiance data from the SOlar Radiation and Climate Experiment (SORCE) Total Irradiance Monitor has been released. This version includes... 相似文献