Algorithm for Harmonic Tidal Analysis along T/P Tracks： Taking Differences of Observed Sea Surface Heights at Adjacent Points as Observations

An algorithm （differential mode） is presented for the improvement of harmonic tidal analysis along T/P tracks, in which the differences between the observed sea surface heights at adjacent points are taken as observations. Also, the observation equations are constrained with the results of the crossover analysis; the parameter estimations are performed at 0.1° latitude intervals by the least squares. Cycle 10 to 330 T/P altimeter data covering the China Sea and the Northwest Pacific Ocean （2°-50° N,105°-150° E） are adopted for a refined along-track harmonic tidal analysis, and harmonic constants of 12 constituents in 8 474 points are obtained, which indicates that the algorithm can efficiently remove non-tidal effects in the altimeter observations, and improve the precision of tide parameters. Moreover, parameters along altimetry tracks represent a smoother distribution than those obtained by traditional algorithms. The root mean squares of the fitting errors between the tidal height model and the observations reduce from 11 cm to 1.3 cm.

Tidal Analysis of High and Low Water Data

The harmonic analysis method based on high and low water levels is discussed in this paper. In order to make full use of the information of high and low water observations (the time derivative of water level at the observation time is zero), the weight coefficient, w, is introduced to control the importance of the part related to this information in the error formula. The major diurnal constituents, O 1 and K 1, and semi diurnal constituents, N 2, M 2 and S 2 are selected directly from the monthly data analysis, and some other important constituents, P 1, ν 2 and K 2, are included as the inferred constituents. The obtained harmonic constants of the major constituents are very close to those obtained from the analysis of hourly data, and this shows that high and low water data can be used to extract tidal constants with high accuracy. The analysis result also shows that the inference and the weighting coefficient are important in the high and low water data analysis, and it is suggested that w ≥1 should be taken in monthly high and low water data analysis. This analysis method can be used directly to analyze altimetric data with w =0.

Association of breastfeeding with tidal breathing analysis in infants with bronchiolitis

BACKGROUND Tidal breathing flow-volume(TBFV)analysis provides important information about lung mechanics in infants.AIM To assess the effects of breastfeeding on the TBFV measurements of infants who recover from acute bronchiolitis.METHODS In this cross-sectional study,TBFV analysis was performed in infants with bronchiolitis prior to hospital discharge.The ratio of time to peak expiratory flow to total expiratory time(tPEF/tE)at baseline and after the administration of 400 mcg salbutamol was evaluated.RESULTS A total of 56 infants(35 boys),aged 7.4±2.8 mo,were included.Of them,12.5%were exposed to tobacco smoke and 41.1%were breastfed less than 2 mo.There were no differences in baseline TBFV measurements between the breastfeeding groups;however,those who breastfed longer than 2 mo had a greater change in tPEF/tE after bronchodilation(12%±10.4%vs 0.9%±7.1%;P<0.001).Moreover,there was a clear dose-response relationship between tPEF/tE reversibility and duration of breastfeeding(P<0.001).In multivariate regression analysis,infants who breastfed less(regression coefficient-0.335,P=0.010)or were exposed to cigarette smoke(regression coefficient 0.353,P=0.007)showed a greater change in tPEF/tE after bronchodilation,independent of sex,prematurity,and family history of asthma or atopy.CONCLUSION Infants who recover from bronchiolitis and have a shorter duration of breastfeeding or are exposed to cigarette smoke,have TBFV measurements indicative of obstructive lung disease.

Tidal harmonic analysis of TOPEX/POSEIDON data in the Northwest Pacific by introducing difference-ratio relations

The difference-ratio relations are introduced to separate tidal constituents that are aliaseddue to the sampling interval and sampling span of the TOPEX/POSEIDON altimeter. It is found that some tidal constituents such as K_1 and SSA, though aliased at along track points, are not aliased at crossover points beeause the data at crossover points are double those at along track points. So the harmonic analysis method can be employed directly for the analysis of time series at crossover points. Then the difference-ratio relations from crossover points are introduced to analyze the time series at along track points. The TOPEX/POSEIDON data in the Northwest Pacific are analyzed with this method. The results from this method agree well with tidal constants from tidal gauges.

Spatial Distribution Characteristics of Surface Tidal Currents in the Southwest of Taiwan Strait

This study was conducted on the spatial distribution characteristics of surface tidal currents in the southwestern Taiwan Strait based on the quasi-harmonic analysis of current data obtained by two high frequency surface wave radar(HFSWR) systems. The analysis shows that the tidal current pattern in the southwestern Taiwan Strait is primarily semi-diurnal and influenced significantly by shallow water constituents. The spatial distribution of tidal current ellipses of M2 is probably affected by the interaction between two different systems of tide wave, one from the northern mouth of Taiwan Strait and the other from the Bashi Channel. The directions of the major axes of M2 tidal current ellipses coincide roughly with the axis of the Taiwan Strait. The spatial distribution of the magnitudes of the probable maximum current velocity(PMCS) shows gradual increase of the velocity from northeast to southwest, which is in accordance with the spatial distribution of the measured maximum current velocity(MMCS). The directions of the residual currents are in accordance with the direction of the prevailing monsoon wind at the Taiwan Strait and the direction of the Taiwan warm current during summer. The bathymetry also shows a significant effect on the spatial distribution characteristics of tidal currents.