ABSTRACT. This is Part II of a contribution on Brazilian sea levels -Part I dealt with the seasonal variability. It examines the sea level changes along the Brazilian coast from series with less than 40 years of measurement, against the background of changes in series of all continents and islands around the world, considering data distributed by the Permanent Service for Mean Sea Level (PSMSL). The method of analysis follows the display of the data in a: 1) first plot of relative sea level trends (C), against the length of the series (L) expressed in years and a: 2) second plot showing the relative sea level regression coefficients (C), versus the corresponding correlation values (m). The first plot of all PSMSL data exhibited a cusped like shape of the distribution of (C), having maxima values about 10-20 cm/cty for the longest series (120-137 years), indicating the overall positive value of the global relative sea level trend. Similar first plot, a regional plot of African and South American data adjusted to the same global relative mean level, showed that the Brazilian trends (C), are mostly concentrated in the positive side of the cusped: (ports of Belém, Fortaleza. Recife, Canavieiras, Salvador, Ilha Fiscal, Rio de Janeiro, Ubatuba, Cananeia, and Imbituba) which have a mean value within 30 to 40 cm/cty. The second plot, with all set of PSMSL data, was necessary in order to display trend values of non simultaneous series of different continental borders and lengths in the same bin. The plot gave two different linear inclinations for trend values within ±0.3 cm/y, in the positive and negative sides of the figure. The global ratio obtained for the trends was R = −1.2, suggesting also, from the linearity of the plot, that the trends and correlation values are statistically dependent variables. The graph produced a different value for global balance of the value C obtained in the first plot. Similar regional second plot of the African Atlantic and South American borders, which include the Brazilian data, also gave rise to two new regression lines with trend C*1<0 and C*2>0, with a ratio R = −2.2, involving bins of m and C values that are also null in the vicinity of zero. This regionally plot confirmed the result of the second plot with PSMSL series that they (C and m), globally, should be dependent statistical variables. These findings, however, do not change the fact that the regional series with trends 0.2 cm/year have correlation values m<0.3, whatever their lengths, and that the mean value of the relative sea level, along the Brazilian coast, is increasing with an estimated rate of 30 to 40 cm/cty. Further work is under way, aiming at solving the above apparently contradictory results.Keywords: sea level, Brazilian coast, PSMSL series, global relative sea level, imbalance of relative sea level. RESUMO.Estaé a segunda parte de uma contribuição sobre os níveis do mar na costa brasileira -a parte I tratou da variação sazonal -ela examina as mudanças do nível do mar ao longo da costa brasileira a partir de sér...
SynopsisIt is shown how to get rid of iterative process to compute waveZengths and how the ceZerities and their derivatives can be computed in terms ofwaveZengths for any depth~ without using hyperboZic functions. -BackgroundIt is well known that the pressure wave records have a strong attenuation of the high frequency components of the wave train, and that such records can not b~ corrected in the time domain. In fact the Corrections would be feasible in the frequency domain, after the Fourier analysis of the pressure records, in terms of the frequency of the Fourier lines. Such corrections are usually computed iteratively because they are given in terrns of the wavelength which is the independent variable in the frequency equation. This problem was solved using polynomia~s and we can show that a similar solution can be found to compute celerities.According to the wave linear theory the celerity corresponding to a wave number k and a depth d is given by c = ~f tanh (kd).In addition for deep seas expression (la) can be changed into we obtain tanh (kd). The main problem ~s now to solve this equation for z. Since the series development of tanh z converges for
The tidal analysis of data from the Equatorial region, given by inverted echo-sounders, show considerable residuals in the frequency band of approximately 2 cycles per day. In the even harmonics of 4 and 6 cycles per day, tidal components statistically not negligible are also identified. Spectral analysis of temperature series from the same area show, on the other hand, variabilities in the same frequency bands, which suggests the occurrence of internal waves with energy distributed in these frequency bands, in the Atlantic Equatorial area.
Análises de dados de maré, da zona equatorial, obtidos com ecobatímetros invertidos, mostram consideráveis resíduos na faixa de freqüências com aproximadamente dois ciclos por dia. Nos harmônicos pares com 4 e 6 ciclos por dia são também identificadas componentes de maré estatisticamente não desprezíveis. Análises espectrais de séries de temperatura obtidas na mesma área mostram, 218 por outro lado, variabilidades na mesma faixa de freqüências, o que sugere a ocorrência, na área equatorial Atlântica, de ondas internas com energia distribuída nessas faixas espectrais
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