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111.
Scott D. Woodruff Henry F. Diaz Steven J. Worley Richard W. Reynolds Sandra J. Lubker 《Climatic change》2005,73(1-2):169-194
Many surface marine meteorological observations (∼125 million) from ships' logbooks have been assembled in the International
Comprehensive Ocean-Atmosphere Data Set (ICOADS) back to the late 18th century. We describe the makeup of the available data
before 1950, and a recent update for that period incorporating a variety of US and international sources – focusing on the
background, digitization, and processing of the US Maury Collection, which provides the earliest data (mainly 1830–1860) currently
blended into ICOADS. We also describe planned data and metadata additions to early ICOADS. Among these, the new Climatological
Database for the World's Oceans (CLIWOC) will extend and enhance coverage for 1750–1854. Prospects for data improvements and
homogeneity enhancements to further benefit climate research are also discussed. 相似文献
112.
Drying of masonry specimens was monitored by means of a two-dimensional (2D) magnetic resonance imaging (MRI) technique. The
external surfaces stayed wet for longer if NaCl was present instead of pure water only. This corroborates many practical observations
that salts aggravate dampness in masonry. A slower evaporation process and not hygroscopicity was the cause. That suggests
that salt-induced dampness may, in general, arise simply from changes in the drying process of masonry materials. That also
implies that the height and depth at which crystallization occurs in walls may depend on the relative equilibrium humidity
(RHeq) and other properties of salts that influence drying of porous materials. Evaporation rates of free surfaces of pure
water and saturated NaCl solution were measured by a gravimetric technique. The results indicate that slow drying of salt-contaminated
materials is not due only to the lower RHeq of salt solutions. The effective surface of evaporation is likely to be reduced
perhaps due to blocking of pores by salt crystals. Final salt-distribution maps of the specimens show that: (a) salts may
affect the inner materials of the masonry, even in evaporation-induced processes that lead crystallization to occur predominantly
on the external surface; (b) distinct internal distribution patterns occur if masonry composition varies.
Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. 相似文献
113.
Chemical composition and nutrient concentrations of 39 relatively poorly known Patagonian lakes (38–50°S and from 70° to 68°W) are described and analysed using principal component analysis (PCA). The general relationships between nutrients (total phosphorus, bioavailable phosphorus and dissolved inorganic nitrogen) and plankton biomass are examined.We seek to demonstrate that the extreme oligotrophy characterising many lakes and reservoirs of the Argentine Patagonian region of South America owes more to nitrogen deficiency than to a shortage of available phosphorus. The data show a range of trophic conditions with variable water chemistry characteristics.The first two axes of the PCA ordination explain most of the variance (63%). The first component of the variance in the environmental data is a trophic gradient, with positive correlations with the concentrations of nutrients (TP, SRP, DIN) and electrical conductivity and a negative correlation with transparency. For all the reservoirs considered, the calculated annual, summer and winter chlorophyll-a carrying capacities of the available phosphorus were consistently and significantly (P<0.05) in excess of observations but maximum chlorophyll-a values correlate with DIN availability. Indeed the chlorophyll-a carrying capacities, as an index of the resource-sustainable maximum biomass, of the available nitrogen gives a better predictive yield relationship than does P. Our findings are remarkable in so far as the general expectation that dinitrogen-fixing phytoplankton should thrive in the absence of dissolved inorganic nitrogen, at least to the supportive limits of the available phosphorus, is unfulfilled. 相似文献
114.
Salt decay is a very destructive mechanism that affects frequently the porous building materials of our architectural heritage. Sodium sulfate is one of the salts found in this context. It usually demonstrates high destructive power in salt crystallization tests because it can crystallize not only during evaporative processes but also when the temperature drops or when the salt solution comes into contact with pre-existing crystals. However, the use of extreme temperatures or successive wet/dry cycles also makes these tests unrepresentative of reality. To verify whether sodium sulfate can also be so destructive in field conditions, we have performed crystallization tests consisting of a single isothermal drying event. Three natural stones, relevant for the architectural heritage, were used for the purpose: Bentheimer sandstone, Ançã limestone, and a current Portuguese limestone of low porosity. The stones gave rise to distinct salt decay patterns: efflorescence, multilayer delamination and unilayer delamination, respectively. These morphological alterations were characterized at the micrometer scale by a new method based on what we have called the alteration kinetics curve. Such curve is calculated from topographic profiles obtained by a non-contact optical technique. The multilayer and unilayer delamination decay were also monitored by time-lapse photography. The work led us to conclude that sodium sulfate can indeed be also very destructive in field-representative conditions. Moreover, it showed that the optical method can be a valuable aid in the development of more realistic salt crystallization tests. 相似文献