A review of the feasibility, costs, and benefits of platform-based open ocean aquaculture in the Gulf of Mexico     

Mark J. KaiserBrian Snyder  Yunke Yu 《Ocean & Coastal Management》2011,54(10):721-730

Platform-based open ocean aquaculture (or mariculture) is a fledgling industry with a unique set of risks and uncertainties. In the past two decades, several commercial and experimental platform-based mariculture projects have been launched in the United States, however, all these projects failed or were abandoned because of operational problems or legal issues. The oil and gas infrastructure in the Gulf of Mexico is well suited for mariculture systems as these platforms are large, sturdy and long lasting, and designed to operate in the offshore environment. The purpose of this paper is to discuss the costs and benefits of a open ocean aquaculture industry in the Gulf of Mexico with particular focus on platform-based aquaculture. The opportunities for the use of idle oil and gas structures for open ocean aquaculture are limited, but the reuse of previously removed structures may have more promise.  相似文献   

Can ensembles of regional climate model simulations improve results from sensitivity studies?     

Travis A. O��Brien  Lisa C. Sloan  Mark A. Snyder 《Climate Dynamics》2011,37(5-6):1111-1118

Intrinsic variability (IV) in regional climate models (RCMs) is often assumed to be small because at climatological timescales, the model solutions tend to be dominated by the model??s lateral boundary conditions. Recent studies have indicated that this IV may actually be large in certain instances for some variables. Direct interpretation of anomalies from RCM sensitivity studies relies on the assumption that differences between model simulations are entirely due to a physical forcing. However, if IV is as large or larger than the physical signal, then this assumption is violated. Using a 20 member ensemble of RCM simulations, we verify that IV of precipitation within a RCM can be large enough to violate the sensitivity study assumption, and we show that generating ensembles of simulations can help reduce the level of IV. We also present two indicators that can rule out the influence of IV when it is ambiguous whether anomalies within a sensitivity study are due to the sensitivity perturbation or whether they are due to IV.  相似文献   

Major auroral substorm features in the dark sector observed by a USAF DMSP satellite     

A.L. Snyder  S.-I. Akasofu 《Planetary and Space Science》1974,22(11):1511-1512

Synoptic auroral photographs acquired by a United States Air Force DMSP satellite have provided the data necessary for an improved understanding of the common auroral phenomena that occur during the substorm expansive phase. Specifically, it is recognized that diffuse auroras (patches, large scale wave structures and Omega bands) form an integral part of the auroral substorm and that their morphological features should be added in the substorm pattern proposed by Akasofu (1964). Several other important auroral substorm features have been added to or corrected in the original pattern. A revised substorm pattern at about the maximum epoch of the substorm is presented.  相似文献   

Influence of irrigated agriculture on diurnal surface energy and water fluxes, surface climate, and atmospheric circulation in California   总被引：1，自引：0，他引：1  

Lara M. Kueppers  Mark A. Snyder 《Climate Dynamics》2012,38(5-6):1017-1029

The impact of land use change on regional climate can be substantial but also is variable in space and time. Past observational and modeling work suggests that in a ‘Mediterranean’ climate such as in California’s Central Valley, the impact of irrigated agriculture can be large in the dry season but negligible in the wet season due to seasonal variation in surface energy partitioning. Here we report further analysis of regional climate model simulations showing that diurnal variation in the impact of irrigated agriculture on climate similarly reflects variation in surface energy partitioning, as well as smaller changes in net radiation. With conversion of natural vegetation to irrigated agriculture, statistically significant decreases of 4–8?K at 2?m occurred at midday June–September, and small decreases of ~1?K occurred in winter months only in relatively dry years. This corresponded to reduced sensible heat flux of 100–350?W?m^?2 and increased latent heat fluxes of 200–450?W?m^?2 at the same times and in the same months. We also observed decreases of up to 1,500?m in boundary layer height at midday in summer months, and marginally significant reductions in surface zonal wind speed in July and August at 19:00 PST. The large decrease in daytime temperature due to shifts in energy partitioning overwhelmed any temperature increase related to the reduced zonal sea breeze. Such changes in climate and atmospheric dynamics from conversion to (or away from) irrigated agriculture could have important implications for regional air quality in California’s Central Valley.  相似文献   

Book reviews     

Bradford Snyder  William B. Size  Thomas A. Jones 《Mathematical Geology》1996,28(5):679-685

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Argon‐40‐argon‐39 chronology and petrogenesis along the eastern limb of the Moon from Luna 16, 20 and 24 samples     

B. A. Cohen  G. A. Snyder  C. M. Hall  L. A. Taylor  M. A. Nazarov 《Meteoritics & planetary science》2001,36(10):1345-1366

Abstract— Eighteen new lithic fragments from the Soviet Luna missions have been analyzed with electron microprobe and ⁴⁰Ar‐³⁹Ar methods. Luna 16 basalt fragments have aluminous compositions consistent with previous analyses, but have two distinct sets of well‐constrained ages (3347 ± 24 Ma, 3421 ± 30 Ma). These data, combined with other Luna 16 basalt ages, imply that there were multiple volcanic events filling Mare Fecunditatis. The returned basalt fragments have relatively old cosmicray exposure (CRE) ages and may have been recovered from the ejecta blanket of a young (1 Ga), nearby crater. A suite of highlands rocks (troctolites and gabbros) is represented in the new Luna 20 fragments. One fragment is the most compositionally primitive (Mg# = 91–92) spinel troctolite yet found. Both troctolites have apparent crystallization ages of 4.19 Ga; other rocks in the suite have progressively younger ages and lower Mg#s. The age and composition progression suggests that these rocks may have crystallized from a single source magma, or from similar sources mobilized at the same time. Within the new Luna 24 basalt fragments is a quench‐textured olivine vitrophyre with the most primitive composition yet analyzed for a Luna 24 basalt, and several much more evolved olivine‐bearing basalts. Both new and previously studied Luna 24 very low‐Ti (VLT) basalt fragments have a unimodal age distribution (3273 ± 83 Ma), indicating that most returned samples come from a single extrusive episode within Mare Crisium much later than the Apollo 17 VLT basalts (3.6–3.7 Ga).  相似文献   

The continuity of the auroral oval in the afternoon sector     

A.L. Snyder  S.-I. Akasofu  D.S. Kimball 《Planetary and Space Science》1975,23(1):225-227

United States Air Force DMSP satellite auroral images and South Pole auroral all-sky camera data are presented to provide new direct evidence that the afternoon sector auroras lie within a continuous oval belt. An example is also presented to illustrate that afternoon substorm auroras occur within the auroral oval configuration.  相似文献   

Iodine as a tracer of organic material: I results from gas hydrate systems and fore arc fluids     

U. Fehn  G.T. Snyder  Y. Muramatsu 《Journal of Geochemical Exploration》2007,95(1-3):66

The strong association of iodine with organic material and the presence of the cosmogenic radioisotope ¹²⁹I make the iodine isotopic system useful in tracing and dating organic materials and their derivatives. We present here results from two new applications of this system, investigations of gas hydrates from the Peru Margin (ODP Leg 201, Site 1230) and of fluids collected from the fore arc region of the North Island, New Zealand. Pore fluids from Site 1230 are strongly enriched in iodine and show a distinct decrease in ¹²⁹I/I ratios from 920 × 10^− 15 close to the surface to 140 × 10^− 15 at a depth of 200 mbsf, suggesting the presence of a shallow, young source and deep, old source of fluids. The fore arc fluids from New Zealand are also enriched in iodine and show a similar range in ¹²⁹I/I ratios. In both cases minimum ages are calculated to be between 40 and 60 Ma for these fluids. The results are in good agreement with earlier investigations of gas hydrate systems at Blake Ridge and Nankai Trough and of fore arc fluids from Central America and Japan, but are not compatible with derivation from subducting sediments in active margins. The results indicate that continental margins contain large amounts of old iodine, reflecting the presence of large quantities of organic material stored in these regions. Results for gas hydrate systems and fore arc fluids show similar characteristics, but differ strongly from those obtained for fluids collected from the main zones of volcanic activity associated with active margins.  相似文献   

Petrogenesis of lunar meteorite EET 96008     

Mahesh Anand  Lawrence A. Taylor  Gregory A. Snyder  Yuji Sano 《Geochimica et cosmochimica acta》2003,67(18):3499-3518

Lunar meteorite EET 96008 is a fragmental breccia that predominantly consists of basaltic mineral clasts (0.5-2 mm), along with minor lithic fragments and breccia clasts. The matrix consists mainly of smaller mineral fragments (<0.5 mm), bound by glassy cement, the majority of which are pyroxene and plagioclase. The pyroxene possesses extensive exsolution lamellae. These lamellae, up to 1 μm in width, are atypical for mare-basalts. One of the distinguishing textures of EET 96008 is the presence of small pockets (∼400 × 500 μm) of mesostasis areas consisting of coarse (∼20 μm) intergrowths of ferroaugite, fayalite and Si-rich glass. Laths of ilmenite, armalcolite, apatite and whitlockite are also distributed in these areas. Ilmenite grains are abundant and dispersed throughout the thin sections. Chromite and ulvöspinel are present but in minor abundance. Troilite, generally rare in this rock, occurs as several grains in one pyroxene crystal. FeNi metal is conspicuously absent from this meteorite.The molar Fe/Mn ratio in olivines and pyroxenes and the age of the meteorite are evidence for a lunar origin. The mineralogy of EET 96008 shows close affinity to a mare-basalt source, albeit with possible minor highland/non-mare components. The bulk-rock, major-, trace- and rare-earth-element (REE) contents are similar to that of very low-titanium (VLT) basalts, which have experienced extreme fractional crystallization to the point of silicate liquid immiscibility. Mineralogical and textural features of this sample suggest that at least some of the breccia components were derived from a slow-cooled magma. The mineralogy and petrology of EET 96008 is strikingly similar to the lunar meteorite EET 87521, and we support the conclusion that EET 96008 and EET 87521 should be paired.Isochron ages of 3530 ± 270 Ma for apatite and 3519 ± 100 Ma for whitlockite of this rock are consistent with derivation from a mare-basalt precursor. These ages are within error of the low-Ti basalts, dated from the Apollo 12 and 15 sites. The whole-rock, platinum-group-element (PGE) contents of EET 96008 overlap with pristine low-Ti mare basalts, suggesting the presence of only a minimal extraterrestrial component.  相似文献   

Sgr B2中处于振动激发态的CH_3CN分子     

缪妍缇  曾琴  L．E．Snyder 《天文学报》1998,(1)

使用BIMA的C位形混合波寻联结9元天线阵,对SgrB2（N）和SgrB2（M）观测了CH3CN分子振动激发态v8＝1的6k－5k线系.仅在SgrB2（N）的10＂×14＂区域里探测到上述发射线．在8．5kpe的距离下,该区域的相应线尺寸是0．41pc×0．58pc．对于SgrB2（M）没有探测到高于均方根噪音的发射流量密度．经粗略地估计,SgrB2（N）区的振动激发温度约为300K．针对此线系的激发机制以及SgrB2（N）区和SgrB2（M）区物理条件之间的差别进行了讨论．  相似文献