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Banglin Zhang Vijay Tallapragada Fuzhong Weng Jason Sippel Zaizhong Ma 《大气科学进展》2015,32(12):1575-1582
The four-dimensional variational(4D-Var) data assimilation systems used in most operational and research centers use initial condition increments as control variables and adjust initial increments to find optimal analysis solutions. This approach may sometimes create discontinuities in analysis fields and produce undesirable spin ups and spin downs. This study explores using incremental analysis updates(IAU) in 4D-Var to reduce the analysis discontinuities. IAU-based 4D-Var has almost the same mathematical formula as conventional 4D-Var if the initial condition increments are replaced with time-integrated increments as control variables.The IAU technique was implemented in the NASA/GSFC 4D-Var prototype and compared against a control run without IAU. The results showed that the initial precipitation spikes were removed and that other discontinuities were also reduced,especially for the analysis of surface temperature. 相似文献
424.
Holley Jason R. McComas Katherine A. Lambert Catherine E. Snider Natalie P. Tucker Grace K. 《Natural Hazards》2022,113(1):615-640
Natural Hazards - Drawing from protection motivation theory (PMT), we examined how place attachment and negative emotions, alongside threat and coping appraisals, personal experiences, and... 相似文献
425.
Malmgren Katherine A. C. Neves Maria Gurdak Jason J. Costa Luis Monteiro Jos P. 《Hydrogeology Journal》2022,30(3):767-782
Hydrogeology Journal - Aquifers are a fundamental source of freshwater, yet they are particularly vulnerable in coastal regions with Mediterranean type climate, due to both climatic and... 相似文献
426.
“All the World's a Stage”: A GIS Framework for Recreating Personal Time‐Space from Qualitative and Quantitative Sources 下载免费PDF全文
This article presents a methodological model for the study of the space‐time patterns of everyday life. The framework utilizes a wide range of qualitative and quantitative sources to create two environmental stages, social and built, which place and contextualize the daily mobilities of individuals as they traverse urban environments. Additionally, this study outlines a procedure to fully integrate narrative sources in a GIS. By placing qualitative sources, such as narratives, within a stage‐based GIS, researchers can begin to tell rich spatial stories about the lived experiences of segregation, social interaction, and environmental exposure. The article concludes with a case study utilizing the diary of a postal clerk to outline the wide applicability of this model for space‐time GIS research. 相似文献
427.
3D desktop-based virtual environments provide a means for displaying quantitative data in context. Data that are inherently spatial in three dimensions may benefit from visual exploration and analysis in relation to the environment in which they were collected and to which they relate. We empirically evaluate how effectively and efficiently such data can be visually analyzed in relation to location and landform in 3D versus 2D visualizations. In two experiments, participants performed visual analysis tasks in 2D and 3D visualizations and reported insights and their confidence in them. The results showed only small differences between the 2D and 3D visualizations in the performance measures that we evaluated: task completion time, confidence, complexity, and insight plausibility. However, we found differences for different datasets and settings suggesting that 3D visualizations or 2D representations, respectively, may be more or less useful for particular datasets and contexts. 相似文献
428.
Soils at the hyperarid margin: The isotopic composition of soil carbonate from the Atacama Desert, Northern Chile 总被引:1,自引:0,他引:1
Jay Quade Jason A. Rech Julio L. Betancourt Mary T.K. Kalin 《Geochimica et cosmochimica acta》2007,71(15):3772-3795
We evaluate the impact of exceptionally sparse plant cover (0-20%) and rainfall (2-114 mm/yr) on the stable carbon and oxygen composition of soil carbonate along elevation transects in what is among the driest places on the planet, the Atacama Desert in northern Chile. δ13C and δ18O values of carbonates from the Atacama are the highest of any desert in the world. δ13C (VPDB) values from soil carbonate range from −8.2‰ at the wettest sites to +7.9‰ at the driest. We measured plant composition and modeled respiration rates required to form these carbonate isotopic values using a modified version of the soil diffusion model of [Cerling (1984) Earth Planet. Sci. Lett.71, 229-240], in which we assumed an exponential form of the soil CO2 production function, and relatively shallow (20-30 cm) average production depths. Overall, we find that respiration rates are the main predictor of the δ13C value of soil carbonate in the Atacama, whereas the fraction C3 to C4 biomass at individual sites has a subordinate influence. The high average δ13C value (+4.1‰) of carbonate from the driest study sites indicates it formed—perhaps abiotically—in the presence of pure atmospheric CO2.δ18O (VPDB) values from soil carbonate range from −5.9‰ at the wettest sites to +7.3‰ at the driest and show much less regular variation with elevation change than δ13C values. δ18O values for soil carbonate predicted from local temperature and δ18O values of rainfall values suggest that extreme (>80% in some cases) soil dewatering by evaporation occurs at most sites prior to carbonate formation. The effects of evaporation compromise the use of δ18O values from ancient soil carbonate to reconstruct paleoelevation in such arid settings. 相似文献
429.
Hydro-meteorological influences and multimodal suspended particle size distributions in the Belgian nearshore area (southern North Sea) 总被引:3,自引:2,他引:3
Michael Fettweis Matthias Baeye Byung Joon Lee Peihung Chen Jason C. S. Yu 《Geo-Marine Letters》2012,32(2):123-137
Suspended particulate matter (SPM) concentration and particle size distribution (PSD) were assessed in a coastal turbidity
maximum area (southern North Sea) during a composite period of 37 days in January–April 2008. PSDs were measured with a LISST
100X and classified using entropy analysis in terms of subtidal alongshore flow. The PSDs during tide-dominated conditions
showed distinct multimodal behaviour due to flocculation, revealing that the building blocks of flocs consist of primary particles
(<3 μm) and flocculi (15 μm). Flocculi comprise clusters of clay minerals, whereas primary particles have various compositions
(calcite, clays). The PSDs during storms with a NE-directed alongshore subtidal current (NE storms) are typically unimodal
and characterised by mainly granular material (silt, sand) resuspended from the seabed. During storms with a SW-directed alongshore
subtidal current (SW storms), by contrast, mainly flocculated material can be identified in the PSDs. The findings emphasise
the importance of wind-induced advection, alongshore subtidal flow and highly concentrated mud suspensions (HCMSs) as regulating
mechanisms of SPM concentration, as well as other SPM characteristics (cohesiveness or composition of mixed sediment particles)
and size distribution in a high-turbidity area. The direction of subtidal alongshore flow during SW storm events results in
an increase in cohesive SPM concentration, HCMS formation, and the armouring of sand; by contrast, there is a decrease in
cohesive SPM concentration, no HCMS formation, and an increase in sand and silt in suspension during NE storms. 相似文献
430.
Mesozoic radiolarian faunas from the northwest Ilocos Region,Luzon, Philippines and their tectonic significance 下载免费PDF全文
Karlo L. Queaño Edanjarlo J. Marquez Carla B. Dimalanta Jonathan C. Aitchison Jason R. Ali Graciano P. Yumul Jr 《Island Arc》2017,26(4)
Northwestern Ilocos Norte in Luzon, Philippines, exposes cherts, peridotite and a variety of metamorphic rocks including chlorite schist, quartzo‐feldspathic schist, muscovite schist and actinolite schist. These rocks are incorporated within a tectonic mélange, the Dos Hermanos Mélange, which is thrust onto the turbidite succession of the Eocene Bangui Formation and capped by the Upper Miocene Pasuquin Limestone. The radiolarian assemblages constrain the stratigraphic range of the cherts to the uppermost Jurassic to Lower Cretaceous. Stratigraphically important species include Eucyrtidiellum pyramis (Aita), Hiscocapsa acuta (Hull), Protunuma japonicus (Matsuoka & Yao), Archeodictyomitra montisserei (Squinabol), Hiscocapsa asseni (Tan), Cryptamphorella conara (Foreman) and Pseudodictyomitra carpatica (Lozyniak). The radiolarian biostratigraphic data provide evidence for the existence of a Mesozoic basinal source from which the cherts and associated rocks were derived. Crucial to determining the origin of these rocks is their distribution and resemblance with known mélange outcrops in Central Philippines. The mélange in the northwestern Ilocos region bears similarities in terms of age and composition with those noted in the western part of the Central Philippines, particularly in the islands of Romblon, Mindoro and Panay. The existence of tectonic mélanges in the Central Philippines has been attributed to the Early to Middle Miocene arc–continent collision. This event involved the Philippine Mobile Belt and the Palawan Microcontinental Block, a terrane that drifted from the southeastern margin of mainland Asia following the opening of the South China Sea. Such arc–continent collision event could also well explain the existence of a tectonic mélange in northwestern Luzon. 相似文献