scholarly journals Lunar Tides and the Long-Term Variation of the Peak Latitude Anomaly of the Summer Sub-Tropical High Pressure Ridge over Eastern Australia

2012 ◽  
Vol 6 (1) ◽  
pp. 49-60 ◽  
Author(s):  
Ian R.G. Wilson
Keyword(s):  
High Pressure ◽  
Tidal Cycle ◽  
Seasonal Cycles ◽  
Resonance Model ◽  
Lunar Tides ◽  
Tidal Forces ◽  
Pressure Ridge ◽  
Eastern Australia ◽  
Long Term Changes

This study looks for evidence of a correlation between long-term changes in the lunar tidal forces and the interannual to decadal variability of the peak latitude anomaly of the summer (DJF) subtropical high pressure ridge over Eastern Australia (L) between 1860 and 2010. A simple “resonance” model is proposed that assumes that if lunar tides play a role in influencing L, it is most likely one where the tidal forces act in “resonance” with the changes caused by the far more dominant solar-driven seasonal cycles. With this type of model, it is not so much in what years do the lunar tides reach their maximum strength, but whether or not there are peaks in the strength of the lunar tides that re-occur at the same time within the annual seasonal cycle. The “resonance” model predicts that if the seasonal peak lunar tides have a measurable effect upon L then there should be significant oscillatory signals in L that vary in-phase with the 9.31 year draconic spring tides, the 8.85 year perigean spring tides, and the 3.80 year peak spring tides. This study identifies significant peaks in the spectrum of L at 9.4 (+0.4/-0.3) and 3.78 (± 0.06) tropical years. In addition, it shows that the 9.4 year signal is in-phase with the draconic spring tidal cycle, while the phase of the 3.8 year signal is retarded by one year compared to the 3.8 year peak spring tidal cycle. Thus, this paper supports the conclusion that long-term changes in the lunar tides, in combination with the more dominant solar-driven seasonal cycles, play an important role in determining the observed inter-annual to decadal variations of L.

scholarly journals Flexible approach for quantifying average long-term changes and seasonal cycles of tropospheric trace species

2019 ◽  
Author(s):  
David D. Parrish ◽  
Richard G. Derwent ◽  
Simon O'Doherty ◽  
Peter G. Simmonds
Keyword(s):  
Time Series ◽  
Seasonal Cycle ◽  
Linear Trend ◽  
Power Series Expansion ◽  
Mathematical Representation ◽  
Seasonal Cycles ◽  
Data Sets ◽  
Significant Information ◽  
Long Term Changes

Abstract. We present an approach to derive a systematic mathematical representation of the statistically significant features of the average long-term changes and seasonal cycle of concentrations of trace tropospheric species. The results for two illustrative data sets (time series of baseline concentrations of ozone and N2O at Mace Head, Ireland) indicate that a limited set of seven or eight parameter values provides this mathematical representation for both example species. This method utilizes a power series expansion to extract more information regarding the long-term changes than can be provided by oft-employed linear trend analyses. In contrast, the quantification of average seasonal cycles utilizes a Fourier series analysis that provides less detailed seasonal cycles than are sometimes represented as twelve monthly means; including that many parameters in the seasonal cycle representation is not usually statistically justified, and thereby adds unnecessary noise to the representation and prevents a clear analysis of the statistical uncertainty of the results. The approach presented here is intended to maximize the statistically significant information extracted from analyses of time series of concentrations of tropospheric species regarding their mean long-term changes and seasonal cycles, including non-linear aspects of the long-term trends. Additional implications, advantages and limitations of this approach are discussed.

scholarly journals Zonal Similarity of Long‐Term Changes and Seasonal Cycles of Baseline Ozone at Northern Midlatitudes

2020 ◽  
Vol 125 (13) ◽  
Author(s):  
David D. Parrish ◽  
Richard G. Derwent ◽  
Wolfgang Steinbrecht ◽  
René Stübi ◽  
Roeland Van Malderen ◽  
...  
Keyword(s):  
Seasonal Cycles ◽  
Long Term Changes

Long-term changes in some benthic species in the Firth of Clyde, with particular reference to Tellina tenuis da Costa

1986 ◽  
Vol 90 ◽  
pp. 287-302 ◽  
Author(s):  
P. R. O. Barnett ◽  
J. Watson
Keyword(s):  
Seawater Temperature ◽  
Present Knowledge ◽  
Seasonal Cycles ◽  
Benthic Species ◽  
Temperature Changes ◽  
Annual Variations ◽  
Long Term Changes ◽  
Natural Temperature ◽  
A Site

SynopisPresent knowledge of long-term changes in benthic species in the Firth of Clyde is reviewed.Recent work on the annual variations in seasonal cycles of the sand-dwelling bivalve Tellina tenuis da Costa shows some correlations with natural and man-made variations in seawater temperature. Between 1973 and 1984 inclusive good settlements of young occurred on the two beaches examined in the autumns of years when higher mean seawater temperatures occurred in June and July. The implications are discussed in relation to cycles of climatic change. In general, settlements at Hunterston, a thermally enriched area, were considerably greater than at Kames Bay, a site affected only by natural temperature changes. However, T. tenuis at Kames Bay grew to much larger maximum sizes than at Hunterston, except in 1979, when Hunterston animals were larger. The possible interactions of food availability and the modifying effects of heated discharges are discussed.Earlier results by Dr A. C. Stephen between 1926 and 1951 are reassessed in the light of present knowledge.

scholarly journals Flexible approach for quantifying average long-term changes and seasonal cycles of tropospheric trace species

2019 ◽  
Vol 12 (6) ◽  
pp. 3383-3394 ◽  
Author(s):  
David D. Parrish ◽  
Richard G. Derwent ◽  
Simon O'Doherty ◽  
Peter G. Simmonds
Keyword(s):  
Time Series ◽  
Seasonal Cycle ◽  
Linear Trend ◽  
Power Series Expansion ◽  
Mathematical Representation ◽  
Seasonal Cycles ◽  
Data Sets ◽  
Significant Information ◽  
Long Term Changes

Abstract. We present an approach for deriving a systematic mathematical representation of the statistically significant features of the average long-term changes and seasonal cycle of concentrations of trace tropospheric species. The results for two illustrative data sets (time series of baseline concentrations of ozone and N2O at Mace Head, Ireland) indicate that a limited set of seven or eight parameter values provides this mathematical representation for both example species. This method utilizes a power series expansion to extract more information regarding the long-term changes than can be provided by oft-employed linear trend analyses. In contrast, the quantification of average seasonal cycles utilizes a Fourier series analysis that provides less detailed seasonal cycles than are sometimes represented as 12 monthly means; including that many parameters in the seasonal cycle representation is not usually statistically justified, and thereby adds unnecessary “noise” to the representation and prevents a clear analysis of the statistical uncertainty of the results. The approach presented here is intended to maximize the statistically significant information extracted from analyses of time series of concentrations of tropospheric species, regarding their mean long-term changes and seasonal cycles, including nonlinear aspects of the long-term trends. Additional implications, advantages and limitations of this approach are discussed.

Long-term changes in the numbers of Helicoverpa punctigera (Lepidoptera: Noctuidae) in a cotton production landscape in northern New South Wales, Australia

2016 ◽  
Vol 107 (2) ◽  
pp. 174-187 ◽  
Author(s):  
G.H. Baker ◽  
C.R. Tann
Keyword(s):  
New South ◽  
New South Wales ◽  
Habitat Type ◽  
Bt Cotton ◽  
Cotton Production ◽  
Bt Resistance ◽  
South Wales ◽  
Eastern Australia ◽  
Long Term Changes

AbstractTwo noctuid moths, Helicoverpa punctigera and Helicoverpa armigera, are pests of several agricultural crops in Australia, most notably cotton. Cotton is a summer crop, grown predominantly in eastern Australia. The use of transgenic (Bt) cotton has reduced the damage caused by Helicoverpa spp., but the development of Bt resistance in these insects remains a threat. In the past, large populations of H. punctigera have built up in inland Australia, following autumn-winter rains. Moths have then migrated to the cropping regions in spring, when their inland host plants dried off. To determine if there have been any long-term changes in this pattern, pheromone traps were set for H. punctigera throughout a cropping landscape in northern New South Wales from 1992 to 2015. At least three generations of moths were caught from spring to autumn. The 1st generation (mostly spring migrants) was the most numerous. Trap captures varied between sites and decreased in time, especially for moths in the 1st generation. Nearby habitat type influenced the size of catch and there was some evidence that local weather also influenced the numbers of moths caught. There was no correlation between trap catches in the cropping region and rainfall in the inland. In addition, there was little evidence that Bt cotton has reduced the abundance of H. punctigera at landscape scale. The apparent decline in the number of presumably Bt susceptible moths arriving each spring in the cropping regions from inland habitats is of concern in relation to the management of Bt resistance.

Effects of high pressure on the crystallization of carbon fiber reinforced polyetheretherketone (CF/PEEK) laminate composites

1990 ◽  
Vol 48 (4) ◽  
pp. 876-877
Author(s):  
Hong-Ming Lin ◽  
C. H. Liu ◽  
R. F. Lee
Keyword(s):  
High Pressure ◽  
Carbon Fiber ◽  
Sample Surface ◽  
High Yield ◽  
Fiber Reinforced ◽  
Laminate Composites ◽  
Peek Composite ◽  
Continuous Carbon Fiber ◽  
Carbon Fiber Reinforced

Polyetheretherketone (PEEK) is a crystallizable thermoplastic used as composite matrix materials in application which requires high yield stress, high toughness, long term high temperature service, and resistance to solvent and radiation. There have been several reports on the crystallization behavior of neat PEEK and of CF/PEEK composite. Other reports discussed the effects of crystallization on the mechanical properties of PEEK and CF/PEEK composites. However, these reports were all concerned with the crystallization or melting processes at or close to atmospheric pressure. Thus, the effects of high pressure on the crystallization of CF/PEEK will be examined in this study.The continuous carbon fiber reinforced PEEK (CF/PEEK) laminate composite with 68 wt.% of fibers was obtained from Imperial Chemical Industry (ICI). For the high pressure experiments, HIP was used to keep these samples under 1000, 1500 or 2000 atm. Then the samples were slowly cooled from 420 °C to 60 °C in the cooling rate about 1 - 2 degree per minute to induce high pressure crystallization. After the high pressure treatment, the samples were scanned in regular DSC to study the crystallinity and the melting temperature. Following the regular polishing, etching, and gold coating of the sample surface, the scanning electron microscope (SEM) was used to image the microstructure of the crystals. Also the samples about 25mmx5mmx3mm were prepared for the 3-point bending tests.

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