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71.
A.W. Jones R.J. Davis A. Wilkinson G. Giardino S.J. Melhuish H. Asareh R.D. Davies A.N. Lasenby 《Monthly notices of the Royal Astronomical Society》2001,327(2):545-551
We present the joint analysis of two 5-GHz interferometric surveys of the northern sky, taken with different baselines. The two surveys were carried out on the Jodrell Bank 5-GHz interferometer based at Manchester. The Maximum Entropy Method is used to check the consistency of the two surveys and the final two-dimensional maps are used, together with low-frequency full sky surveys, to put constraints on the Galactic spectral index. It is found that synchrotron emission is the dominant process at high Galactic latitudes below 5 GHz. 相似文献
72.
H. L. Davies J. B. Keene K. Hashimoto M. Joshima J. E. Stuart D. L. Tiffin 《Geo-Marine Letters》1987,6(4):181-191
The floor of the western Solomon Sea (for new bathymetric map see inside back cover of this issue) is dominated by the arched and ridged basement of the Solomon Sea Basin, the partly-sediment-filled New Britain Trench, and a more completely filled trench, the Trobriand Trough. There is a deep basin where the trenches join (149° Embayment), and a silled basin west of the New Britain Trench (Finsch Deep). Submarine canyons descend from the west and south to the 149° Embayment. Abyssal fans and plains are structurally defined and locally disturbed by young faults. Probable submerged pinnacle reefs stand in water depths as great as 1,200 m. 相似文献
73.
74.
M. Nonino J. P. Henry C. Fanti R. Fanti & J. Davies 《Monthly notices of the Royal Astronomical Society》1998,299(2):332-340
We report on new optical, infrared and radio observations of the Seyfert galaxy Markarian 315. We confirm the detection at all wavelengths of a secondary peak of emission, which lies ≈ 2 arcsec east of the Seyfert nucleus. Moreover, we detect a chain-like structure which surrounds the active nucleus, with peculiar behaviour westward of the nucleus. We consider different interpretations for the origin of the secondary peak emission. 相似文献
75.
The effect of uncertainty in aerodynamic resistance on evaporation estimates from the combination model 总被引:1,自引:0,他引:1
Evaporation estimates from a soybean crop calculated from the combination model are insensitive to aerodynamic resistance. The insensitivity arises from a strong link between evaporation and the vapour pressure deficit of the air and bulk stomatal resistance. The sensitivity of aerodynamic resistance to errors in surface roughness and zero-plane displacement is considered. The resistance is found to be more sensitive to errors in surface roughness than to errors in zero-plane displacement. However, large errors in these have little effect on calculated evaporation. Both surface roughness and zero-plane displacement are empirically related to crop height and leaf area index. Errors incurred by ignoring bluff-body effects and atmospheric stability are small in estimating both resistance and evaporation. Evaporation can be calculated adequately from empirical estimates of surface roughness and zero-plane displacement and single-level measurements of windspeed. 相似文献
76.
Surveys of natural populations of mussels have identified areas of mercury contamination in the Firth of Forth, Scotland. A field bio-assay technique has been devised which accurately reflects the mean total mercury concentration in the surrounding seawater. The detection limit of the technique is estimated at 5–20 ng Hg l.?1, and consequently the method can detect comparatively small enhancements over background mercury concentrations in estuarine and sea water. 相似文献
77.
78.
Synoptic Climatology of Air Pollution in Moscow 总被引:8,自引:0,他引:8
Summary Seasonal synoptic indices are developed employing principal components analysis and cluster analysis for Moscow and using
surface and upper air meteorological data. Synoptic types are analysed in terms of circulation patterns and air mass characteristics.
The indices are used to examine weather-induced variability in CO and NO2 concentrations for different land use types and in the context of multiple pollution sources. Anticyclonic conditions in
spring, summer and autumn are identified as producing high pollution concentrations. Local depressions developing in the low
pressure gradient fields in summer are another synoptic type resulting in high levels of air pollution. Extremely cold anticyclonic
conditions in winter result in high CO but low NO2 levels. Weather patterns characterised by strong winds associated either with an established zonal flow or the passage of
a cold front caused high NO2 concentrations in the areas affected by elevated sources.
Received October 28, 1997 Revised January 26, 1998 相似文献
79.
Despite the long history of the continuum equation approach in hydrology, it is not a necessary approach to the formulation of a physically based representation of hillslope hydrology. The Multiple Interacting Pathways (MIPs) model is a discrete realization that allows hillslope response and transport to be simultaneously explored in a way that reflects the potential occurrence of preferential flows and lengths of pathways. The MIPs model uses random particle tracking methods to represent the flow of water within the subsurface alongside velocity distributions that acknowledge preferential flows and transition probability matrices, which control flow pathways. An initial realization of this model is presented here in application to a tracer experiment carried out in Gårdsjön, Sweden. The model is used as an exploratory tool, testing several hypotheses in relation to this experiment. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
80.
Storm events are major transporters of faecal microbial contaminants, but few studies have reported storm loads or concentration dynamics in relation to discharge or other pollutants, notably fine sediment. Episodically, high loads of faecal contamination during storm flows impact downstream uses of water bodies, particularly contact recreation and shellfish harvesting. We examined the storm dynamics of Escherichia coli, turbidity and discharge in the mixed land use Motueka catchment (2047 km2; 60% forest and 19% pasture) to gain insights into E. coli sources and transport. We also explored different approaches for calculating E. coli loads. Discharge and field turbidity were recorded continuously, and E. coli concentrations were sampled during events, over a 13‐month period near the mouth of the Motueka River. E. coli loads were estimated by interpolation, averaging estimators and by using linear regression with smearing correction of the log‐transformed variables: discharge, turbidity, and both turbidity and discharge. The annual E. coli load was dominated (~98%) by export during events. Comparison of monthly monitoring with the intensive storm monitoring campaign suggests that simple stratification of the sampling into storm and baseflow would greatly improve export estimates. E. coli peak concentrations always preceded discharge and turbidity peaks (which had similar timing). Turbidity can be a useful surrogate for faecal microbes in smaller catchments, but in the Motueka turbidity was no better for predicting E. coli concentration than discharge. Runoff from grazed pasture and direct deposition from livestock are probably the ultimate E. coli sources in the Motueka catchment. However, in‐channel stores seem to dominate E. coli dynamics during events and account for the typical feature of bacterial concentrations peaking ahead of discharge and turbidity. This study demonstrates the importance of storm events to faecal microbial loads and shows that E. coli concentration dynamics may contrast with those of turbidity. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献