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1.
F. Carrier B. Bourdon . Pili C. Truffert R. Wyns 《Journal of Geochemical Exploration》2006,88(1-3):266
Airborne gamma-ray spectrometry data (uranium, potassium and thorium contents) reveal geochemical heterogeneities within the monolithological Hyrôme watershed (ca. 150 km2) in the Armorican massif (western France). Our observations and computations provide important constraints on the spatial distribution and the associated magnitudes of chemical erosion processes at the scale of a small watershed. Two distinct, partially preserved, weathering profiles exhibit a strong correlation between regolith evolution and airborne-derived K/Th ratios, suggesting that the variability is linked to supergene processes. Using both airborne data and laboratory measurements on rock samples, the total net export of potassium has been estimated at 422 ± 50 kg/m2 and the chemical weathering rate of potassium at 17 ± 2 kg/km2/a. 相似文献
2.
Long-range precipitation forecasts are useful when managing water supplies.Oceanicatmospheric oscillations have been shown to influence precipitation.Due to a longer cycle of some of the oscillations,a short instrumental record is a limitation in using them for long-range precipitation forecasts.The influence of oscillations over precipitation is observable within paleoclimate reconstructions;however,there have been no attempts to utilize these reconstructions in precipitation forecasting.A data-driven model,KStar,is used for obtaining long-range precipitation forecasts by extending the period of record through the use of reconstructions of oscillations.KStar is a nearest neighbor algorithm with an entropy-based distance function.Oceanic-atmospheric oscillation reconstructions include the El Nino-Southern Oscillation(ENSO),the Pacific Decadal Oscillation(PDO),the North Atlantic Oscillation(NAO),and the Atlantic Multi-decadal Oscillation(AMO).Precipitation is forecasted for 20 climate divisions in the western United States.A 10-year moving average is applied to aid in the identification of oscillation phases.A lead time approach is used to simulate a one-year forecast,with a 10-fold cross-validation technique to test the models.Reconstructions are used from 1658-1899,while the observed record is used from 1900-2007.The model is evaluated using mean absolute error(MAE),root mean squared error(RMSE),RMSE-observations standard deviation ratio(RSR),Pearson’s correlation coefficient(R),NashSutcliffe coefficient of efficiency(NSE),and linear error in probability space(LEPS) skill score(SK).The role of individual and coupled oscillations is evaluated by dropping oscillations in the model.The results indicate ’good’ precipitation estimates using the KStar model.This modeling technique is expected to be useful for long-term water resources planning and management. 相似文献
3.
T.C. Teixeira J. Christensen-Dalsgaard F. Carrier C. Aerts S. Frandsen D. Stello T. Maas M. Burnet H. Bruntt J.R. de Medeiros F. Bouchy H. Kjeldsen F. Pijpers 《Astrophysics and Space Science》2003,284(1):233-236
This work reports the discovery of solar-type oscillations in thegiant star Hydrae. 相似文献
4.
Dennis Stello Hans Kjeldsen Timothy R. Bedding Joris De Ridder Conny Aerts Fabien Carrier SØren Frandsen 《Solar physics》2004,220(2):207-228
The discovery of solar-like oscillations in the giant star ξ Hya (G7 III) was reported by Frandsen et al. (2002). Their frequency analysis was very limited due to alias problems in the data set (caused by single-site observations).
The extent to which the aliasing affected their analysis was unclear due to the unknown damping time of the stellar oscillation
modes. In this paper we describe a simulator created to generate time series of stochastically excited oscillations, which
takes as input an arbitrary window function and includes both white and non-white noise. We also outline a new method to compare
a large number of simulated time series with an observed time series to determine the damping time, amplitude, and limited
information on the degree of the stochastically excited modes. For ξ Hya we find the most likely amplitude to be ∼ 2 m s−1, in good agreement with theory (Houdek and Gough, 2002), and the most likely damping time to be ∼ 2 days, which is much shorter
than the theoretical value of 15–20 days calculated by Houdek and Gough (2002). 相似文献
5.
Commt A. Carrier 《Journal of Geodesy》1950,24(2):146-153
Résumé On voit que l’erreur de réduction à l’horizon est prépondérante quand les pentes atteignent en moyenne 10/100 et quandn est seulement de l’ordre de 15. Ces conditions se présentent parfois dans la polygonation ordinaire. La précision de 1/15.000
à laquelle on est alors limité, avec le niveau de sensibilité faible, par le fait de l’erreur de réduction à l’horizon, est
plus que suffisante pour cette opération.
Par contre, l’erreur de réduction à l’horizon devient très faible quand la pente moyenne ne dépasse pas 3/100 et quandn dépasse 100. Ces conditions se présentent dans la mesure des bases et l’erreur de réduction à l’horizon est alors de l’ordre
de 1/250.000, et même inférieure si l’on utilise le niveau de grande sensibilité et sin dépasse 100. Les autres erreurs peuvent alors intervenir et réduire cette précision, notamment l’erreur sur la température
du fil,par temps ensoleillé, l’erreur d’étalonnage à l’œil nu, etc...
Entre ces deux extrêmes, c’est-à-dire pour une pente moyenne de 6/100, et une valeur den variant de 50 à 100, l’erreur de réduction à l’horizon est de l’ordre de 1/100.000 et se conjugue alors avec d’autres erreurs,
ramenant la précision à une valeur de l’ordre de 1/75.000, convenant aux déterminations de points canevas, et même à la mesure
de bases secondaires.
L’appareil donne ainsi une gamme de précisions allant de 1/15.000 de 1/200.000, suivant les conditions d’emploi: pente, temps
ensoleillé ou couvert, etc... et suivant les opérations effectuées: polygonation ordinaire, polygonation de précision, intersection
et triangulation par mesure directe des c?tés, base topographique, base semi-géodésique. Il apporte au topographe la possibilité
d’effectuer les mesures linéaires avec une précision correspondant à celle obtenue dans les mesures angulaires avec les tachéomètres
modernes (genre Wild) et il rétablit ainsi l’équilibre indispensable dans les précisions données par les deux catégories d’instruments.
Constructeur: SIMPA, 112, rue de Charenton, Paris. 相似文献
6.
Lunar soil grain size distribution 总被引：1，自引：0，他引：1
W. David Carrier III 《Earth, Moon, and Planets》1973,6(3-4):250-263
A comprehensive review has been made of the currently available data for lunar grain size distributions. It has been concluded that there is little or no statistical difference among the large majority of the soil samples from the Apollo 11, 12, 14, and 15 missions. The grain size distribution for these soils has reached a steady state in which the comminution processes are balanced by the aggregation processes. The median particle size for the steady-state soil is 40 to 130 µm. The predictions of lunar grain size distributions based on the Surveyor television photographs have been found to be quantitatively in error and qualitatively misleading. 相似文献
7.
Prepared by the MSR Campaign Science Group A. D. Czaja M.-P. Zorzano the rest of the MCSG team with Chairs G. Kminek M. A. Meyer Members D. W. Beaty E. Sefton-Nash B. L. Carrier F. Thiessen T. Haltigin A. Bouvier N. Dauphas K. L. French L. J. Hallis R. L. Harris E. Hauber L. E. Rodriguez S. P. Schwenzer A. Steele K. T. Tait M. T. Thorpe T. Usui J. Vanhomwegen M. A. Velbel S. Edwin K. A. Farley D. P. Glavin A. D. Harrington L. E. Hays A. Hutzler M. Wadhwa 《Meteoritics & planetary science》2023,58(6):885-896
The Mars 2020/Mars Sample Return (MSR) Sample Depot Science Community Workshop was held on September 28 and 30, 2022, to assess the Scientifically-Return Worthy (SRW) value of the full collection of samples acquired by the rover Perseverance at Jezero Crater, and of a proposed subset of samples to be left as a First Depot at a location within Jezero Crater called Three Forks. The primary outcome of the workshop was that the community is in consensus on the following statement: The proposed set of ten sample tubes that includes seven rock samples, one regolith sample, one atmospheric sample, and one witness tube constitutes a SRW collection that: (1) represents the diversity of the explored region around the landing site, (2) covers partially or fully, in a balanced way, all of the International MSR Objectives and Samples Team scientific objectives that are applicable to Jezero Crater, and (3) the analyses of samples in this First Depot on Earth would be of fundamental importance, providing a substantial improvement in our understanding of Mars. At the conclusion of the meeting, there was overall community support for forming the First Depot as described at the workshop and placing it at the Three Forks site. The community also recognized that the diversity of the Rover Cache (the sample collection that remains on the rover after placing the First Depot) will significantly improve with the samples that are planned to be obtained in the future by the Perseverance rover and that the Rover Cache is the primary target for MSR to return to Earth. 相似文献
8.
Kathryn T. Stevenson M. Nils Peterson Howard D. Bondell Susan E. Moore Sarah J. Carrier 《Climatic change》2014,126(3-4):293-304
Though many climate literacy efforts attempt to communicate climate change as a risk, these strategies may be ineffective because among adults, worldview rather than scientific understanding largely drives climate change risk perceptions. Further, increased science literacy may polarize worldview-driven perceptions, making some climate literacy efforts ineffective among skeptics. Because worldviews are still forming in the teenage years, adolescents may represent a more receptive audience. This study examined how worldview and climate change knowledge related to acceptance of anthropogenic global warming (AGW) and in turn, climate change risk perception among middle school students in North Carolina, USA (n?=?387). We found respondents with individualistic worldviews were 16.1 percentage points less likely to accept AGW than communitarian respondents at median knowledge levels, mirroring findings in similar studies among adults. The interaction between knowledge and worldview, however, was opposite from previous studies among adults, because increased climate change knowledge was positively related to acceptance of AGW among both groups, and had a stronger positive relationship among individualists. Though individualists were 24.1 percentage points less likely to accept AGW than communitarians at low levels (bottom decile) of climate change knowledge, there was no statistical difference in acceptance levels between individualists and communitarians at high levels of knowledge (top decile). Non-White and females also demonstrated higher levels of AGW acceptance and climate change risk perception, respectively. Thus, education efforts specific to climate change may counteract divisions based on worldviews among adolescents. 相似文献
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10.
An assessment of the summertime precipitation climate for the Okefenokee Swamp region was undertaken utilizing daily precipitation data from meteorological sites near the swamp for the period 1955-1980. “Runs of dry days” were investigated in relation to total seasonal precipitation and with regard to the distribution of runs by length. Utilizing Markov chain analysis and regression techniques, relationships between the length of runs of dry days and total seasonal precipitation as well as cumulative number of runs of dry days and total seasonal precipitation were established. However, further analysis of the intensty distribution of daily precipitation suggested that the summertime precipitation climate could best be described utilizing an assessment of days with a significant amount of precipitation rather than by studying runs of dry days. An analytical definition of a “significant rain day” was attempted utilizing the correlation of the number of rain days exceeding a given daily precipitation threshold value versus total seasonal precipitation. The most appropriate threshold value was found to be about 0.6 inches, suggesting that days with greater than this amount of precipitation can be defined as significant rain days. 相似文献