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71.
72.
A.V. Karmalkar M.A. Taylor J. Campbell T. Stephenson M. New A. Centella A. Benzanilla J. Charlery 《Atmósfera》2013,26(2):283-309
Observed and projected changes in climate have serious socio-economic implications for the Caribbean islands. This article attempts to present basic climate change information—based on previous studies, available observations and climate model simulations—at spatial scales relevant for islands in the Caribbean. We use the General Circulation Model (GCM) data included in the Coupled Model Intercomparison Project phase 3 (CMIP3) and the UK Hadley Centre regional climate model (RCM) data to provide both present-day and scenario-based future information on precipitation and temperature for individual island states. Gridded station observations and satellite data are used to study 20th century climate and to assess the performance of climate models. With main focus on precipitation, we also discuss factors such as sea surface temperature, sea level pressure and winds that affect seasonal variations in precipitation. The CMIP3 ensemble mean and the RCM successfully capture the large-scale atmospheric circulation features in the region, but show difficulty in capturing the characteristic bimodal seasonal cycle of precipitation. Future drying during the wet season in this region under climate change scenarios has been noted in previous studies, but the magnitude of change is highly uncertain in both GCM and RCM simulations. The projected decrease is more prominent in the early wet season erasing the mid-summer drought feature in the western Caribbean. The RCM simulations show improvements over the GCM mainly due to better representation of landmass, but its performance is critically dependent on the driving GCM. This study highlights the need for high-resolution observations and ensemble of climate model simulations to fully understand climate change and its impacts on small islands in the Caribbean. 相似文献
73.
F Richard Stephenson and David M Willis describe a rich source of information on aurorae from 17th-century Korea. 相似文献
74.
75.
M. Stephenson J. Klaverkamp M. Motycka C. Baron W. Schwartz 《Journal of Paleolimnology》1996,15(1):99-106
Sediments of Lake 382, Experimental Lakes Area, Canada, were sampled at six sites using a 5-cm Wildco KB core sampler (KB), a similar device incorporating a ball check valve (BC), and a 0.2 m by 1.2 m flat-faced aluminum freeze core sampler (FC). Cores were sectioned at 1-cm intervals to a depth of 15 cm. Contaminant (210Pb and 137Cs) concentrations (Bq g-1) were measured by gamma spectroscopy, and inventories (Bq cm-2) were calculated following standard methods. Sediments collected using FC, BC and KB had similar contaminant concentrations, however, cores collected by FC and BC had lower estimated inventories than KB cores. Differences between estimates appear to be caused by differences in the water content (WC) of core material. Laboratory studies confirm that FC sediments have higher WC than tube-cored sediment. We hypothesize that ice crystal formation increases the WC of freeze cores, resulting in lower contaminant inventories. Loss of surficial sediment caused by a bow wave may have a similar effect on BC samples. We conclude that KB core gear is appropriate for sampling sediments to measure contaminant concentrations and inventories in recently deposited sediments. 相似文献
76.
The total ozone column is well correlated with tropospheric fields such as the heights of the upper tropospheric geopotential
surfaces and thus it can provide useful information on temporal variability in the troposphere. The global availability of
long period satellite measurements of the total ozone column, taken by the TOMS instruments since 1978, provides a valuable
and independent data set for use in studies of seasonal and interannual climate variability. In this study, the global low-frequency
seasonal teleconnections in the observed TOMS data from 1979–91 have been investigated using seasonal teleconnectivity maps
and empirical orthogonal function analysis. They have also been compared with the results from a simulation made with the
atmospheric GCM at Météo-France, having prescribed observed sea surface temperatures for the same period. In the observed
total ozone, strong ENSO-related wave number one longitudinal dipole patterns are seen in both the tropics and in the Southern
Hemisphere extratropics. The model shows much weaker variability in total ozone yet appears to be able to capture similar
teleconnection patterns in the tropics related to ENSO. In the SH extratropics, the model total ozone shows a strong wave
number 3 response rather than the wave number one dipole seen in the observations. A wave number 3 response is also evident
in the 200 hPa geopotential height simulated by the model and in the NCEP analysis, and is consistent with the response in
a linearised barotropic model forced in the Indonesian region. The different responses in the modelled and observed total
ozone, suggest that tropopause effect is not the major factor in the SH extratropics, and it is likely that horizontal ozone
transport also plays a role in this region. Despite a generally poor simulation of the zonal mean total ozone, the model was
able to capture the anomalous strengthening of the SH stationary waves during austral spring of 1988, related to an intense
stratosphere sudden warming.
Received: 21 October 1996 / Accepted: 11 September 1997 相似文献
77.
78.
Michael Martin Gary Ichikawa Jon Goetzl Margarita de los Reyes Mark D. Stephenson 《Marine environmental research》1984,11(2):91-110
Resident populations of Mytilus edulis from Tomales and San Francisco Bay, California, were measured for scope of growth, a physiological integration of the energy consumed by individual animals (feeding rate and assimilation efficiency) less the energy lost in metabolic processes (oxygen consumption and ammonia excretion). Scope for growth of mussels was significantly correlated (p≤ 0·05) with feeding rates. There was a significant decline in the scope for growth between the Golden Gate, at the bay's entrance and RedwoodCity in south San Francisco Bay. The scope for growth in resident M. edulis was significantly negatively correlated (p≤ 0·05) with increased environmental concentrations (from transplanted M. californianus body burden data) of the following trace elements and higher molecular weight chlorinated organic compounds: Cr, Cu, Hg (p ≤ 0·01) and Ag, Al, Zn, total chlordanes, and dieldrin. Scope for growth was significantly correlated (p ≤0·05) with body condition index (dry body weight1shell length). 相似文献
79.
80.
Rhea D. Sanders Kenneth H. Coale Gary A. Gill Allen H. Andrews Mark Stephenson 《Applied Geochemistry》2008
Age-dated sediment cores from 4 remote lakes across California were analyzed for total Hg (HgT) concentration as a function of pre- and post-industrialization. Particle size, magnetic susceptibility and organic C and N, were measured to determine if the Hg concentration in sediment cores could be related to atmospheric deposition and/or watershed processes. Results indicate that (a) for each lake modern (1970–2004) HgT lake sediment concentrations have increased by an average factor of 5 times more than historic (pre-1850) HgT concentrations; (b) the ratio of modern to pre-industrial lake sediment HgT for these lakes are higher than estimated for other locations where atmospheric deposition is presumed to be the main source of Hg; (c) 2 of the 4 studied lakes demonstrated significant relationships between HgT concentrations and percentage organic material (r2 = 0.68 and p < 0.01; r2 = 0.67 and p < 0.01) whereas the other two indicated no significant relationship (r2 = 0.05 and p = 0.51; r2 = 0.12 and p = 0.36). 相似文献