Thermal waves on the Queensland shelf

1983 ◽  
Vol 34 (1) ◽  
pp. 81 ◽  
Author(s):  
JC Andrews
Keyword(s):  
Atmospheric Pressure ◽  
Bottom Water ◽  
Driving Mechanism ◽  
Mean Square ◽  
Thermal Waves ◽  
Root Mean Square Amplitude ◽  
Mean Sea Level ◽  
Long Period ◽  
Short Period ◽  
Break Water

Thermocline waves are found on the continental slope and shelf of Queensland. Slope waves of period near 90 days accompany upwelling and downwelling. Shelf thermal waves are created by onshore surges of shelf- break water, which is 1-4.5�C cooler than lagoon water, depending on the season. The bottom surges are investigated by means of the cross-spectra of temperatures with longshore winds, with atmospheric pressure and with mean sea level. Longshore winds are found to be the driving mechanism and significant coherence is found near periods of 4 and 8 days (summer and winter, respectively) and in a band with periods of 10-70 days, perhaps peaking near 30 days. Correlation and cross-spectral analyses of temperature at sites 100 km apart suggest that the short period thermal waves popagate equatorward wheras the long period waves, which contain most of the thermal covariance, form a standing mode. Cross-spectral analysis of the root mean square amplitude of diurnal thermal variations with the longer-period thermal waves suggests that localized tidal upwelling brings bottom water over reefs.

Noise level variation at norsar and its effect on detectability

1977 ◽  
Vol 67 (2) ◽  
pp. 479-492 ◽  
Author(s):  
F. Ringdal ◽  
H. Bungum
Keyword(s):  
Atmospheric Pressure ◽  
Noise Level ◽  
Amplitude Distribution ◽  
P Wave ◽  
Seasonal Fluctuations ◽  
Long Period ◽  
Short Period ◽  
Noise Data ◽  
Band Pass ◽  
Period Data

Abstract For a 3-year period, noise level measurements of short- and long-period data at NORSAR have been sampled at hourly intervals. Significant seasonal fluctuations in noise level have been found, in particular for long-period data. The noise amplitude distribution is approximately lognormal for band-pass filtered short-period data in the P-wave detection band, while the long-period noise data show a skewness that cannot be represented by a lognormal distribution. Diurnal fluctuations in noise level are quite small, but definitely present both for short and horizontal component long-period data. Cultural sources are found to account for the short-period variability, while the long-period fluctuations are attributed to atmospheric pressure variation. Event detection performance generally follows the noise level trends, with an increase in the number of reported events during summer of about 50 per cent relative to winter.

Calibration Analysis and Noise Estimates of WWSSN Station ALQ (Albuquerque, New Mexico)

2019 ◽  
Vol 91 (3) ◽  
pp. 1359-1366 ◽  
Author(s):  
Adam T. Ringler ◽  
David C. Wilson ◽  
Emily Wolin ◽  
Tyler Storm ◽  
Leo Sandoval
Keyword(s):  
New Mexico ◽  
Root Mean Square Error ◽  
World Wide ◽  
Mean Square ◽  
Noise Levels ◽  
System Noise ◽  
Long Period ◽  
Short Period ◽  
Zero Response ◽  
Seismograph Network

ABSTRACT World-Wide Standardized Seismograph Network (WWSSN) records contain daily calibration pulses that can be used to retrieve the magnification as well as the response of the instrument for a given day record. We analyze a select number of long-period vertical (LPZ) records from WWSSN station ALQ (Albuquerque, New Mexico). Although we find that the response of this instrument varies widely throughout time, we show that in most cases, we are able to estimate a pole-zero response that has a root mean square error of <10%. The variability of responses in historical networks has been reported elsewhere because a large number of adjustments of the galvanometer and seismometer were necessary. Using our derived responses, we estimate noise levels for a number of 1 hr digitized traces. We find that noise levels for the LPZ ALQ records are lower than previously reported, suggesting that these records can resolve smaller amplitude signals than previously suggested. We also find that although care must be taken in the digitization and calibration analysis, we are not limited by noise introduced in the digitization process. Finally, we see that to retrieve the full secondary microseism amplitude, we must use both the LPZ and short-period components because the LPZ component is limited by system noise at periods less than ∼5  s.

scholarly journals Pemodelan pada Proses Cyclostationarity Berdasarkan Data Pasut Cilacap Tahun 2007-2015

2018 ◽  
Vol 2017 (1) ◽  
Author(s):  
Larasati S. Cendani ◽  
N.M.R.R. Cahya Perbani ◽  
Kania Sawitri
Keyword(s):  
Wave Function ◽  
Sea Level ◽  
Wave Model ◽  
Least Square ◽  
Maximum Deviation ◽  
Mean Sea Level ◽  
Long Period ◽  
Short Period ◽  
Period Data ◽  
Period Measurement

ABSTRAK Sesuai prosedur dalam penentuan MSL sejati, pengamatan pasut dilakukan secara terus-menerus selama 18,61 tahun dengan selang waktu satu jam tanpa jeda. Pengamatan pasut tersebut bukanlah suatu hal yang mudah dan hampir tidak dapat untuk dilakukan, MSL yang digunakan untuk kepentingan teknis umumnya ditentukan berdasarkan data pengamatan pasut periode pendek selama 15 atau 29 hari. Periode pendek tersebut memiliki keterbatasan dalam mengakomodasi seluruh faktor yang mempengaruhi MSL. Hipotesis pada penelitian ini MSL bulanan juga memiliki sifat cyclostationarity berdasarkan penelitian pasang tinggi di Benoa, Bali yang memiliki sifat yang sama. Penelitian ini bertujuan memodelkan terjadinya proses cyclostationarity untuk dijadikan sebagai model koreksi mean sea level bulanan dan untuk mengetahui variasi yang terjadi. Pemodelan dilakukan menggunakan fungsi gelombang dua konstanta pasut periode panjang Sa dan Ssa menggunakan analisis harmonik kuadrat terkecil melalui Deret Fourier. Dari penelitian yang telah dilakukan diketahui bahwa model gelombang yang dihasilkan sudah 80% mewakili perilaku MSL bulanan dan simpangan maksimum terhadap MSL bulanan rata-rata sebesar 245 mm. Kata kunci: MSL bulanan, cyclostationarity, fungsi gelombang ABSTRACT In procedure to determine the true mean sea level (MSL), hourly tide measurement should be taken for 18,61 years continuously. That such measurement is not simple and barely possible to establish. In most technical cases, MSL is determined from shot period measurement 15 or 29 days. The limitation of that such short period data is in accommodating all factors with action MSL. In this study the monthly MSL is a cyclostationarity process like spring tides in Benoa, Bali is taken as the hypothesis. This study directed to model cyclostationarity process to build the model of monthly MSL and to find it’s variation. The modeling is accomplished using wave function two long period constituents (Sa and Ssa). Least square harmonic analysis by means of Fourier series is applied. It is found that the wave model from this study represent about 80% of monthly MSL behavior and the average of maximum deviation is 245 mm. Keywords: monthly MSL, cyclostationarity, wave function

Discussion following the presentation by F. Deubner

1977 ◽  
Vol 36 ◽  
pp. 69-74
Keyword(s):  
List Type ◽  
The Sun ◽  
Type Number ◽  
Harmonic Motion ◽  
Locally Excited ◽  
Long Period ◽  
Coherent Wave ◽  
Short Period ◽  
Global Modes

The discussion was separated into 3 different topics according to the separation made by the reviewer between the different periods of waves observed in the sun :1) global modes (long period oscillations) with predominantly radial harmonic motion.2) modes with large coherent - wave systems but not necessarily global excitation (300 s oscillation).3) locally excited - short period waves.

scholarly journals Isolation and Analysis of Six timeless Alleles That Cause Short- or Long-Period Circadian Rhythms in Drosophila

Genetics ◽  
2000 ◽  
Vol 156 (2) ◽  
pp. 665-675
Author(s):  
Adrian Rothenfluh ◽  
Marla Abodeely ◽  
Jeffrey L Price ◽  
Michael W Young
Keyword(s):  
Nuclear Translocation ◽  
Phase Response Curve ◽  
Fixed Number ◽  
Constant Darkness ◽  
Genetic Screens ◽  
Protein Levels ◽  
Long Period ◽  
Short Period ◽  
Molecular Oscillation ◽  
New Alleles

Abstract In genetic screens for Drosophila mutations affecting circadian locomotion rhythms, we have isolated six new alleles of the timeless (tim) gene. Two of these mutations cause short-period rhythms of 21–22 hr in constant darkness, and four result in long-period cycles of 26–28 hr. All alleles are semidominant. Studies of the genetic interactions of some of the tim alleles with period-altering period (per) mutations indicate that these interactions are close to multiplicative; a given allele changes the period length of the genetic background by a fixed percentage, rather than by a fixed number of hours. The timL1 allele was studied in molecular detail. The long behavioral period of timL1 is reflected in a lengthened molecular oscillation of per and tim RNA and protein levels. The lengthened period is partly caused by delayed nuclear translocation of TIML1 protein, shown directly by immunocytochemistry and indirectly by an analysis of the phase response curve of timL1 flies.

scholarly journals Widespread increase in dynamic imbalance in the Getz region of Antarctica from 1994 to 2018

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Heather L. Selley ◽  
Anna E. Hogg ◽  
Stephen Cornford ◽  
Pierre Dutrieux ◽  
Andrew Shepherd ◽  
...  
Keyword(s):  
Drainage Basin ◽  
Satellite Observations ◽  
Driving Mechanism ◽  
West Antarctica ◽  
Mean Sea Level ◽  
The Past ◽  
Global Mean Sea Level ◽  
Forcing Mechanisms ◽  
Global Mean ◽  
Term Response

AbstractThe Getz region of West Antarctica is losing ice at an increasing rate; however, the forcing mechanisms remain unclear. Here we use satellite observations and an ice sheet model to measure the change in ice speed and mass balance of the drainage basin over the last 25-years. Our results show a mean increase in speed of 23.8 % between 1994 and 2018, with three glaciers accelerating by over 44 %. Speedup across the Getz basin is linear, with speedup and thinning directly correlated confirming the presence of dynamic imbalance. Since 1994, 315 Gt of ice has been lost contributing 0.9 ± 0.6 mm global mean sea level, with increased loss since 2010 caused by a snowfall reduction. Overall, dynamic imbalance accounts for two thirds of the mass loss from this region of West Antarctica over the past 25-years, with a longer-term response to ocean forcing the likely driving mechanism.

scholarly journals Wave Force Characteristics of Large-Sized Offshore Wind Support Structures to Sea Levels and Wave Conditions

2019 ◽  
Vol 9 (9) ◽  
pp. 1855
Author(s):  
Youn-Ju Jeong ◽  
Min-Su Park ◽  
Jeongsoo Kim ◽  
Sung-Hoon Song
Keyword(s):  
Shallow Water ◽  
Wave Height ◽  
Wave Force ◽  
Diffraction Effect ◽  
Support Structures ◽  
Sea Levels ◽  
Irregular Wave ◽  
Long Period ◽  
Short Period ◽  
Period Wave

This paper presents the results of wave force tests conducted on three types of offshore support structures considering eight waves and three sea levels to investigate the corresponding wave forces. As a result of this study, it is found that the occurrence of shoaling in shallow water induces a significant increase of the wave force. Most of the test models at the shallow water undergo a nonlinear increase of the wave force with higher wave height increasing. In addition, the larger the diameter of the support structure within the range of this study, the larger the diffraction effect is, and the increase in wave force due to shoaling is suppressed. Under an irregular wave at the shallow water, the wave force to the long-period wave tends to be slightly higher than that of the short period wave since the higher wave height component included in the irregular wave has an influence on the shoaling. In addition, it is found that the influence of shoaling under irregular wave becomes more apparent in the long period.

scholarly journals Epistatic and Synergistic Interactions Between Circadian Clock Mutations in Neurospora crassa

Genetics ◽  
2001 ◽  
Vol 159 (2) ◽  
pp. 537-543
Author(s):  
Louis W Morgan ◽  
Jerry F Feldman
Keyword(s):  
Circadian Clock ◽  
Neurospora Crassa ◽  
Mutant Strain ◽  
Temperature Compensation ◽  
Double Mutant ◽  
Synergistic Interactions ◽  
Long Period ◽  
Double Mutant Strain ◽  
Short Period ◽  
Compensation Mechanisms

Abstract We identified a series of epistatic and synergistic interactions among the circadian clock mutations of Neurospora crassa that indicate possible physical interactions among the various clock components encoded by these genes. The period-6 (prd-6) mutation, a short-period temperature-sensitive clock mutation, is epistatic to both the prd-2 and prd-3 mutations. The prd-2 and prd-3 long-period mutations show a synergistic interaction in that the period length of the double mutant strain is considerably longer than predicted. In addition, the prd-2 prd-3 double mutant strain also exhibits overcompensation to changes in ambient temperature, suggesting a role in the temperature compensation machinery of the clock. The prd-2, prd-3, and prd-6 mutations also show significant interactions with the frq7 long-period mutation. These results suggest that the gene products of prd-2, prd-3, and prd-6 play an important role in both the timing and temperature compensation mechanisms of the circadian clock and may interact with the FRQ protein.

LONG-PERIOD SURFACE-RELATED MULTIPLE SUPPRESSION IN 2D MARINE SEISMIC DATA USING PREDICTIVE DECONVOLUTION AND COMBINATION OF SURFACE-RELATED MULTIPLE ELIMINATION AND PARABOLIC RADON FILTERING

2021 ◽  
Author(s):  
Pimpawee Sittipan ◽  
Pisanu Wongpornchai
Keyword(s):  
Seismic Data ◽  
Seismic Reflection ◽  
Petroleum Reservoirs ◽  
The United States ◽  
Multiple Reflections ◽  
Long Period ◽  
Predictive Deconvolution ◽  
Short Period ◽  
Marine Seismic ◽  
Multiple Elimination

Some of the important petroleum reservoirs accumulate beneath the seas and oceans. Marine seismic reflection method is the most efficient method and is widely used in the petroleum industry to map and interpret the potential of petroleum reservoirs. Multiple reflections are a particular problem in marine seismic reflection investigation, as they often obscure the target reflectors in seismic profiles. Multiple reflections can be categorized by considering the shallowest interface on which the bounces take place into two types: internal multiples and surface-related multiples. Besides, the multiples can be categorized on the interfaces where the bounces take place, a difference between long-period and short-period multiples can be considered. The long-period surface-related multiples on 2D marine seismic data of the East Coast of the United States-Southern Atlantic Margin were focused on this research. The seismic profile demonstrates the effectiveness of the results from predictive deconvolution and the combination of surface-related multiple eliminations (SRME) and parabolic Radon filtering. First, predictive deconvolution applied on conventional processing is the method of multiple suppression. The other, SRME is a model-based and data-driven surface-related multiple elimination method which does not need any assumptions. And the last, parabolic Radon filtering is a moveout-based method for residual multiple reflections based on velocity discrimination between primary and multiple reflections, thus velocity model and normal-moveout correction are required for this method. The predictive deconvolution is ineffective for long-period surface-related multiple removals. However, the combination of SRME and parabolic Radon filtering can attenuate almost long-period surface-related multiple reflections and provide a high-quality seismic images of marine seismic data.

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