On the Calculation of Filter Coefficients for Maximum Entropy Spectral Analysis

Andersen, Nils Axel

doi:10.1190/1.1440413

Cited by 338 publications

(146 citation statements)

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“…2. A 0 represents the annual mean intensity and A 1 is the intensity amplitude of the principal period obtained by Maximum Entropy Method (Anderson, 1974). As it was already shown in Fig.…”

Section: Discussionmentioning

confidence: 67%

First results from mesospheric airglow observations at 7.5º S.

Buriti¹,

Takahashi²,

Gobbi³

2001

Rev. Bras. Geof.

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The Cariri Airglow Observatory has been in operation since November, 1997. This observatory has a multi-filter photometer to measure the airglow emission intensities in the frequencies of OI557.7 nm, OI630.0 nm, NaD, OH(6,2) band, O 2 Atmospheric (0-1) band , and the OH and O 2 rotational temperatures. The observatory is located at São João do Cariri, State of Paraíba, one of the driest region in Northeast Brazil, situated at 7.4 0 S, 36.5 0 W. Day to day continuous observations (13 days around the new moon period) allow us to study nocturnal, day to day and seasonal variation of the airglow emission intensities. The nocturnal variations of the mesospheric emissions and OH(6,2) rotational temperature have shown strong seasonal dependence with maxima in equinox and minima in solstice. The OI557.7 nm presented the largest relative amplitude (0.42) whereas the rotational temperature presented the smallest relative amplitude (~0.03) and annual averages equal to 231 K. The annual averages of the intensities in OI557.7 nm, O 2 (0,1) and OH(6,2) were 124 R, 321 R and 1323 R, respectively. Variation of airglow intensities of 2 and 3 days were observed in OI5577 and O 2 (0,1).Key words: Airglow; Photometer; Rotational temperature. PRIMEIROS RESULTADOS DAS OBSERVAÇÕES DE AIRGLOW

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“…2. A 0 represents the annual mean intensity and A 1 is the intensity amplitude of the principal period obtained by Maximum Entropy Method (Anderson, 1974). As it was already shown in Fig.…”

Section: Discussionmentioning

confidence: 67%

First results from mesospheric airglow observations at 7.5º S.

Buriti¹,

Takahashi²,

Gobbi³

2001

Rev. Bras. Geof.

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“…They have undergone considerable quality control, with random errors reduced to approximately _+0.4øK through optimum interpolation [Gandin, 1963] onto a 2 ø latitude by 5 ø longitude grid at depths of 0, 20, 40, 60, 80, 120, and 160 m each month. Subsequently, for both GISST and BT temperature-gridded fields, gaps in the time record were filled by applying maximum-entropy spectral analysis to each individual time series [Andersen, 1974]. Where gaps exceeded 20% of the record, time sequences were eliminated from further consideration.…”

Section: Observations and Methodsmentioning

confidence: 99%

Response of global upper ocean temperature to changing solar irradiance

White¹,

Lean²,

Cayan³

et al. 1997

J. Geophys. Res.

306

248

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Abstract. By focusing on time sequences of basin-average and global-average upper ocean temperature (i.e., from 40øS to 60øN) we find temperatures responding to changing solar irradiance in three separate frequency bands with periods of >100 years, 18-25 years, and 9-13 years. Moreover, we find them in two different data sets, that is, surface marine weather observations from 1990 to 1991 and bathythermograph (BT) upper ocean temperature profiles from 1955 to 1994. Band-passing basin-average temperature records find each frequency component in phase across the Indian, Pacific, and Atlantic Oceans, yielding global-average records with maximum amplitudes of 0.04 ø _+ 0.01øK and 0.07 ø _+ 0.01øK on decadal and interdecadal scales, respectively. These achieve maximum correlation applied wavelet transform analysis to the global-average northern hemisphere portion of this data set, finding significant solar-related signals on both decadal and interdecadal scales. We inquire into the global connection between decadal and interdecadal climate variability and changing solar irradiance by focusing upon the oceanic portion of the global surface temperature record from 1990 to 1991. We complement it with a new global upper ocean temperature record compiled mostly from bathythermograph (BT) measurements collected from 1955 to 1994. The latter allows us to examine the heat budget of the oceanic response to changing solar irradiance in a simple way not possible over land, answering the question, Where is the anomalous heat from changing solar irradiance stored? By taking this approach we are able to achieve complementary specifications of solar-related decadal and interdecadal signals in upper ocean temperature in these two independent data sets (and in three independent ocean basins). Three different statistical techniques (i.e., power spectra, multichannel singular spectrum analysis (MSSA), and empirical orthogonal function (EOF)) are used to show significant associations between global-average upper ocean temperature and solar irradiance on both decadal and interdecadal timescales. These yield estimates for phase lags of the global-average sea surface temper- 3255

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“…Most spikes were removed manually. Short gaps up to 3 hours were filled linearly, while longer gaps up to 12 days were filled spectrally following Andersen [1974]. After as many gaps were filled as possible the data were low passed with a 60+ 1+60 point Cosine-Lanczos filter that removed the diurnal fides, inertial oscillations (23.9 hours at 30 ø of latitude), and all higher frequencies, leaving <0.5% of the energy at 25 hours.…”

Section: Current Meter Arraymentioning

confidence: 99%

East Australian Current volume transports at 30°S: Estimates from the World Ocean Circulation Experiment hydrographic sections PR11/P6 and the PCM3 current meter array

Mata¹,

Tomczak²,

Wijffels³

et al. 2000

J. Geophys. Res.

112

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Abstract. Between September 1991 and March 1994 the oceanic region off the east coast of Australia at 30øS was the subject of an intense observational program Part of the World Ocean Circulation Experiment, the objective was to improve our understanding of the dynamics of the East Australian Current (EAC) and to measure its volume and energy flux. The two main components were the Pacific Current Meter Array 3 (PCM3) with six moorings spanning a total distance of 120 km, and repeat, high-resolution hydrographic surveys. The long-term average from PCM3 shows the EAC as a narrow, swift, and highly variable current centered at 40 km from the coast with strong shear in the upper 1000 m and mean southward velocities of 0.6 m s 4 in the core. The measurements also revealed a thick countercurrent underneath the poleward flow. The mean volume transport for the entire section covered by the array (between the coast and 154.4øE) was 22.1+4.6 Sv toward the south with an rms variability of 30 Sv. Combining the data from the PCM3 array with the hydrographic sections generated nine detailed snapshots of the absolute geostrophic current field. The snapshots were used to evaluate the reliability of the PCM3 data for determining volume transports. The rms difference between transports derived from direct current observations and from hydrographic data was 3.8 Sv, indicating that the PCM3 array can be used to describe the current variability despite the sparse spatial distribution of velocity measurements. Transport variability was dominated by periods between 90 and 140 days, which are attributed to eddy shedding in the region. Occasional intense northward flow events were observed where total transports reached up to 50 Sv northward. On those occasions the southward boundary current changed from being surface intensified and mainly baroclinic to northward and more barotropic, related to the northward migration past the array of the EAC coastal separation point.

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On the Calculation of Filter Coefficients for Maximum Entropy Spectral Analysis

Cited by 338 publications

References 0 publications

First results from mesospheric airglow observations at 7.5º S.

First results from mesospheric airglow observations at 7.5º S.

Response of global upper ocean temperature to changing solar irradiance

East Australian Current volume transports at 30°S: Estimates from the World Ocean Circulation Experiment hydrographic sections PR11/P6 and the PCM3 current meter array

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