A theory of short period tides in a rotating basin

1976 ◽  
Vol 281 (1299) ◽  
pp. 97-111 ◽  
Keyword(s):  
Analytical Model ◽  
Lake Michigan ◽  
Diurnal Tide ◽  
Semidiurnal Tide ◽  
Variable Depth ◽  
Amplitude Response ◽  
Tidal Forcing ◽  
Nodal Lines ◽  
Short Period ◽  
Crude Approximation

An analytical model of the forced tides in a rotating and enclosed basin of variable depth is formulated which includes the effects of basin shape, the rotating Fronde number, latitude, angle of orientation and dissipation on the semidiurnal and diurnal response. To a crude approximation contra solem rotation of nodal lines of the semidiurnal tide and diurnal tide at latitudes north at 45° occurs when the frequency of tidal forcing falls between the frequencies of the transverse and longitudinal free modes of oscillation. Predicted phase responses for the semidiurnal tide agree with measurements in the seven basins studied. The anomolous response found in Lake Michigan by Mortimer & Fee is attributed to bottom friction coincidence with an appropriate angle of orientation of the basin. Amplitude response in all cases is larger than observed which cannot be accounted for generally by reasonable coefficients of friction.

scholarly journals Climatology of mesopause region nocturnal temperature, zonal wind and sodium density observed by sodium lidar over Hefei, China (32° N, 117° E)

2018 ◽  
Vol 18 (16) ◽  
pp. 11683-11695 ◽  
Author(s):  
Tao Li ◽  
Chao Ban ◽  
Xin Fang ◽  
Jing Li ◽  
Zhaopeng Wu ◽  
...  
Keyword(s):  
Zonal Wind ◽  
Momentum Flux ◽  
Model Simulation ◽  
Input Function ◽  
Diurnal Tide ◽  
Semidiurnal Tide ◽  
Mesopause Region ◽  
Short Period ◽  
Semiannual Variation ◽  
Zonal Momentum

Abstract. The University of Science and Technology of China narrowband sodium temperature and wind lidar, located in Hefei, China (32∘ N, 117∘ E), has made routine nighttime measurements since January 2012. A total of 154 nights (∼ 1400 h) of vertical profiles of temperature, sodium density, and zonal wind and 83 nights (∼ 800 h) of vertical flux of gravity wave (GW) zonal momentum in the mesopause region (80–105 km) were obtained during the period from 2012 to 2016. For temperature, it is most likely that the diurnal tide dominates below 100 km in spring, while the semidiurnal tide dominates above 100 km throughout the year. A clear semiannual variation in temperature is revealed near 90 km, in phase with the tropical mesospheric semiannual oscillation (MSAO). The variability in sodium density is positively correlated with temperature below 95 km, suggesting that in addition to dynamics, the chemistry also plays an important role in the formation of sodium atoms. The seasonal variability in sodium density observed by both lidar and satellite generally agrees well with a whole atmosphere model simulation using an updated meteoric input function which includes different cosmic dust sources. For zonal wind, the diurnal tide dominates in both spring and fall, while semidiurnal tide dominates in winter. The observed semiannual variation in zonal wind near 90 km is out of phase with that in temperature, consistent with the tropical MSAO. The lidar observations generally agree with satellite and meteor radar observations as well as model simulations at similar latitude. The 50–70 % of zonal momentum flux is induced by short-period (10 min–2 h) GWs. The large zonal momentum flux in summer and winter due to short-period GWs is clearly anticorrelated with eastward zonal wind maxima below 90 km, suggesting the filtering of short-period GWs by the SAO wind.

A procedure for calibrating short-period telemetered seismograph systems

1988 ◽  
Vol 78 (6) ◽  
pp. 2077-2088
Author(s):  
M. C. Chapman ◽  
J. A. Snoke ◽  
G. A. Bollinger
Keyword(s):  
Dynamic Range ◽  
Low Frequency ◽  
Inertial Mass ◽  
System Response ◽  
Total System ◽  
Electronic Components ◽  
Amplitude Response ◽  
Motion System ◽  
Short Period ◽  
The Hilbert Transform

Abstract Efficient low-frequency calibration of the entire seismograph system can be accomplished by Fourier analysis of the system response to automatically generated transient test functions applied to the seismometer calibration coil. Typically, such calibrations are restricted to frequencies less than 10 Hz by the ambient ground motion, system noise, and limited dynamic range. To extend the calibration to a broader frequency range, we disconnect the seismometer and take advantage of the fact that the relative amplitude response of the electronic components in most systems can be measured with high accuracy at frequencies from as low as 0.02 Hz to the Nyquist frequency (e.g., 50 Hz) using standard electronics test equipment. The low-frequency amplitude response of the seismometer can then be isolated by dividing the total system response by that obtained for the electronic components. An iterative least-squares procedure is used to estimate the natural frequency and damping coefficient of the seismometer, along with a scaling parameter that specifies the absolute gain of the system. The phase response of the system is calculated directly from the amplitude response using the Hilbert transform. The procedure assumes that the seismometer is an ideal damped harmonic oscillator and that the system as a whole acts as a minimum phase filter. The only instrumental constants that must be known from independent measurement are the seismometer calibration coil force constant and the inertial mass.

Analytical Dynamic Performance Modeling for Individual C-block Actuators

1999 ◽  
Vol 121 (2) ◽  
pp. 221-230 ◽  
Author(s):  
A. J. Moskalik ◽  
D. Brei
Keyword(s):  
Analytical Model ◽  
Performance Modeling ◽  
Natural Frequencies ◽  
Block Design ◽  
Dynamic Performance ◽  
Design Parameters ◽  
Good Match ◽  
Amplitude Response ◽  
Trade Offs ◽  
Analytical Dynamic

C-blocks are mid-range piezoelectric actuators that show promise for use in dynamic applications, such as noise and vibration control. This paper presents an analytical model of an individual C-block actuator, including the identification of the natural frequencies and the description of the amplitude response across the frequency spectrum. In addition, an experimental study with three case studies is presented investigating the accuracy of the model and the sensitivity of the overall dynamic performance to C-block design parameters. The experimental results showed a good match to the analytical model and outlined the trade-offs between displacement amplitude and bandwidth.

scholarly journals XIII. On the tides of the arctic seas. - Part V. On the tides of refuge cove, wellington channel

1875 ◽  
Vol 165 ◽  
pp. 339-360
Keyword(s):  
Diurnal Tide ◽  
The Arctic ◽  
Semidiurnal Tide ◽  
Arctic Seas ◽  
The Third

The following observations were made by Admiral Sir Leopold M‘Clintock (then Captain) in the month of July 1859, at Port Kennedy, in Bellot Strait, on board the yacht ‘Fox,’ in eleven fathoms depth, lat. 72° 01' N., long. 94° 15' W. The observa­tions were made hourly, and, judging from the consistent and highly interesting results obtained from them, they must have been made and recorded with unusual care. In Table I. the first column contains the Solar Hour, the second contains the Height of Tide, the third contains the Diurnal Tide, and the fourth the Semidiurnal Tide.

scholarly journals Variability of the lunar semidiurnal tidal amplitudes in the ionosphere over Brazil

2021 ◽  
Vol 39 (1) ◽  
pp. 151-164
Author(s):  
Ana Roberta Paulino ◽  
Fabiano da Silva Araújo ◽  
Igo Paulino ◽  
Cristiano Max Wrasse ◽  
Lourivaldo Mota Lima ◽  
...  
Keyword(s):  
Lower Atmosphere ◽  
Electron Content ◽  
Semidiurnal Tide ◽  
Large Power ◽  
Total Electron ◽  
Power Spectral ◽  
Temporal And Spatial Variability ◽  
Short Period ◽  
Main Component ◽  
Almost All

Abstract. The variability in the amplitudes of the lunar semidiurnal tide was investigated using maps of total electron content over Brazil from January 2011 to December 2014. Long-period variability showed that the annual variation is always present in all investigated magnetic latitudes, and it represents the main component of the temporal variability. Semiannual and triannual (two and three times a year, respectively) oscillations were the second and third components, respectively, but they presented significant temporal and spatial variability without a well-defined pattern. Among the short-period oscillations in the amplitude of the lunar tide, the most pronounced ones were concentrated between 7–11 d. These oscillations were stronger around the equinoxes, in particular between September and November in almost all latitudes. In some years, as in 2013 and 2014, for instance, they appeared with a large power spectral density in the winter hemisphere. These observed short-period oscillations could be a result of a direct modulation of the lunar semidiurnal tide by planetary waves from the lower atmosphere and/or due to electrodynamic coupling of E and F regions of the ionosphere.

XXIX. On the tides of Bombay and Kurrachee

1868 ◽  
Vol 158 ◽  
pp. 685-696 ◽  
Keyword(s):  
Royal Society ◽  
Diurnal Tide ◽  
Semidiurnal Tide ◽  
Royal Observatory ◽  
The Subject ◽  
Engineering Survey ◽  
Continuous Curves ◽  
Made In

The tides on the coasts of India present a marked difference from those on our own coasts in the large amount of diurnal inequality to which they are subject. My attention was first directed to the subject in the course of an engineering survey of the Harbour of Kurrachee which I made in 1857-58, when I obtained between three and four months’ continuous observations, a copy of which is deposited with the Royal Society. Subsequently I obtained from the Admiralty, through the kindness of Captain Burdwood, R. N., the loan of the records of three years’ observations taken at Bombay in 1846, 1847, and 1848. Of these I plotted in a series of continuous curves the records for 1846, and deposited them, at the Astronomer Royal’s request, at the Royal Observatory, Greenwich. These records, however, are not perfect. They were made by a self-acting machine, the adjustment of which does not appear to have been always accurately pre­served; and I hope that they will be superseded as data for investigation by a better record 'for the year 1868. Taking them as they were, however, I discussed them to obtain the semimonthly curves of semidiurnal tide, and also formulæ for the approxi­mate determination of diurnal tide.

Responses of sweating and body temperature to sinusoidal exercise

1994 ◽  
Vol 76 (6) ◽  
pp. 2541-2545 ◽  
Author(s):  
F. Yamazaki ◽  
R. Sone ◽  
H. Ikegami
Keyword(s):  
Sensory Stimulation ◽  
Constant Load ◽  
Cycle Ergometer ◽  
Healthy Male ◽  
O2 Uptake ◽  
Amplitude Response ◽  
Short Period ◽  
Sinusoidal Load ◽  
Sinusoidal Pattern ◽  
Male Subjects

This study determined the phase response and amplitude response (delta) of esophageal temperature (T(es)), mean skin temperature (Tsk), and forearm sweating rate (Msw) to sinusoidal work. Six healthy male subjects exercised on a cycle ergometer with a constant load (approximately 35% maximal O2 uptake) for a 30-min period; for the next 40 min they exercised with a sinusoidal load at 25 degrees C at 35% relative humidity. The sinusoidal load varied between approximately 10 and 60% maximal O2 uptake, and three different time periods (1.3, 4, and 8 min) were selected. Each subject performed three experiments that differed only in the timing of sinusoidal work. During the 4- and 8-min periods, T(es), Tsk, and Msw changed almost sinusoidally. The phase of Msw change significantly preceded those of T(es) and Tsk changes (P < 0.05). During the 1.3-min period, the level of T(es) and Tsk remained almost constant (delta T(es) 0.01 +/- 0.00 degrees C, delta Tsk 0.03 +/- 0.01 degrees C), whereas Msw showed a clear sinusoidal pattern. We conclude that the sweating response during sinusoidal work depends on both thermal and nonthermal factors, the latter being emotional, mental, or sensory stimulation. The contribution of the nonthermal factors to the general sweating response during exercise can be separated from that of the thermal factors by using sinusoidal work during a short period (e.g., 1.3 min).

Numerical modal of the tides in the Gulf of Carpentaria and the Arafura Sea

1981 ◽  
Vol 32 (1) ◽  
pp. 31 ◽  
Author(s):  
DJ Webb
Keyword(s):  
Numerical Model ◽  
Linear Time ◽  
Diurnal Tide ◽  
Semidiurnal Tide ◽  
Curved Boundaries ◽  
The North ◽  
Arafura Sea ◽  
Amphidromic Point

A numerical model of the tides in the Gulf of Carpentaria and the Arafura Sea is described and its results presented. The model is linear. time-independent and uses curved boundaries. The results show that the diurnal tide has an amphidromic point near the centre of the Gulf of Carpentaria and that the semidiurnal tide has two amphidromic points-one in the north of the Arafura Sea and a second, virtual one, at Mornington Island. The model also shows that both frictional and resonant effects are important in determining the tides of the region.

scholarly journals Diurnal and semidiurnal tide in the upper middle atmosphere during the first year of simultaneous MF radar observations in northern and southern Japan (45°N and 31°N)

1999 ◽  
Vol 17 (3) ◽  
pp. 405-414 ◽  
Author(s):  
K. Hocke ◽  
K. Igarashi
Keyword(s):  
Middle Atmosphere ◽  
Wave Model ◽  
Global Scale ◽  
Diurnal Tide ◽  
First Year ◽  
Semidiurnal Tide ◽  
Tidal Amplitude ◽  
Latitudinal Dependence ◽  
Waves And Tides ◽  
Mf Radar

Abstract. The climatology of mean wind, diurnal and semidiurnal tide during the first year (1996-1997) of simultaneous wind observations at Wakkanai (45.4°N, 141.7°E) and Yamagawa (31.2°N, 130.6°E) is presented. The locations of the radars allow us to describe the latitudinal dependence of the tides. Tidal amplitude and phase profiles are compared with those of the global scale wave model (GSWM). While the observed amplitude profiles of the diurnal tide agree well with the GSWM values, the observed phase profiles often indicate longer vertical wavelengths than the GSWM phase profiles. In contrast to the GSWM simulation, the observations show a strong bimodal structure of the diurnal tide, with the phase advancing about 6 hours from summer to winter.Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides)

scholarly journals Global distributions of diurnal and semidiurnal tides: observations from HRDI-UARS of the MLT region and comparisons with GSWM-02 (migrating, nonmigrating components)

2004 ◽  
Vol 22 (5) ◽  
pp. 1529-1548 ◽  
Author(s):  
A. H. Manson ◽  
C. Meek ◽  
M. Hagan ◽  
X. Zhang ◽  
Y. Luo
Keyword(s):  
Middle Atmosphere ◽  
Spectral Feature ◽  
Wave Model ◽  
Diurnal Tide ◽  
Wave Number ◽  
Semidiurnal Tide ◽  
Data Set ◽  
Wave Numbers ◽  
Nonmigrating Tides ◽  
Longitudinal Structures

Abstract. HRDI (High Resolution Doppler Interferometer-UARS) winds data have been analyzed in 4°-latitude by 10°-longitude cells at 96km to obtain the global distribution of the solar-tidal amplitudes and phases. The solstices June–July (1993), December–January (1993–1994), and one equinox (September–October, 1994) are analyzed. In an earlier paper (Manson et al., 2002b) the emphasis was solely upon the longitudinal and latitudinal variations of the amplitudes and phases of the semidiurnal (12h) and diurnal (24h) tides. The longitudinal structures were shown to be quite distinctive, and in the case of the EW component of the diurnal tide there were typically four maxima/perturbations of amplitudes or phases around a latitude circle. In this case they tended to be associated with the locations of the major oceans. Here, a spatial complex spectral analysis has been applied to the data set, to obtain the zonal wave numbers for the tides as functions of latitude. For the diurnal tide the dominant s=1 migrating component and nonmigrating tides with wave numbers s=–3, –2, 0, 2 are identified; and for the semidiurnal tide, as well as the dominant s=2 migrating component, the spectra indicate the presence of nonmigrating tides with wave numbers s=–2, 0, 4. These wave numbers are also simply related to the global longitudinal structures in the tidal amplitudes and phases. Comparisons are made with the Global Scale Wave Model (GSWM-02), which now incorporates migrating and nonmigrating tides associated with tropospheric latent heat processes, and offers monthly outputs. For the diurnal tide the dominant nonmigrating tidal spectral feature (94km) is for wave number s=–3; it is relatively stronger than in the HRDI winds, and produces quite consistent structures in the global tidal fields with four longitudinal maxima. Overall, the modelled 24-h tidal amplitudes are larger than observed during the equinox beyond 40° latitude. For the semidiurnal tide, nonmigrating tides are frequently indicated in the spectra with wave numbers s=–2, 0, 6; and there are complementary longitudinal structures in the global tidal fields with two and four maxima evident. Modelled 12-h tidal amplitudes are much smaller than observed during non-winter months beyond 30°. There is a detailed discussion of the spectral features, their seasonal variations, and the similarities with the HRDI tidal data. This discussion is in the context of the inherent limitations of the model.Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; thermospheric dynamics; waves and tides)

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