On the Annual Variations in the Amplitude of 25-70-Day Intraseasonal Atmospheric Oscillations in Central Africa

Alain Tchakoutio Sandjon; Armand Nzeukou

doi:doi:10.11648/j.earth.20160503.11

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On the Annual Variations in the Amplitude of 25-70-Day Intraseasonal Atmospheric Oscillations in Central Africa

Alain Tchakoutio Sandjon, Armand Nzeukou

Received: 25 May 2016 Accepted: 13 July 2016 Published: 23 July 2016

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Abstract

In this paper we analyzed the annual variations in the 25-70-day intraseasonal atmospheric oscillations in central Africa, for the period 1981-2010, using the Outgoing Longwave OLR data. We then extracted the amplitude time series of the dominant modes of intraseasonal variability in 25-70 days filtered OLR anomalies, using Empirical Orthogonal Functions (EOF) analysis. The EOF analysis has shown that three dominant modes characterized the intraseasonal atmospheric oscillation in Central Africa. The amount of variance explained by these three retained EOFs are 19.3%, 13.6% and 11.8% respectively, and they exhibit higher spatial loading over Northern Congo, Southern Ethiopia, and Southwestern Tanzania, respectively. The analysis of Principal Components (PCs) time series showed that the amplitude and of the intraseasonal oscillations (ISO) exhibit large annual variations. In fact the highest values of ISO amplitude are generally observed during October-April season, and much weakened signal the rest of the year. The fraction of yearly Madden Julian Oscillation (MJO) power, occurring within October-April season are 79.3%, 77.92%, 78.73% for EOF1, EOF2, and EOF3, respectively.

DOI	10.11648/j.earth.20160503.11
Published in	Earth Sciences (Volume 5, Issue 3, June 2016)
Page(s)	39-47
Creative Commons	This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.
Copyright	Copyright © The Author(s), 2024. Published by Science Publishing Group

Keywords

Rainfall, ISO Variations, Central Africa, Amplitude

References

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APA Style

Alain Tchakoutio Sandjon, Armand Nzeukou. (2016). On the Annual Variations in the Amplitude of 25-70-Day Intraseasonal Atmospheric Oscillations in Central Africa. Earth Sciences, 5(3), 39-47. https://doi.org/10.11648/j.earth.20160503.11

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ACS Style

Alain Tchakoutio Sandjon; Armand Nzeukou. On the Annual Variations in the Amplitude of 25-70-Day Intraseasonal Atmospheric Oscillations in Central Africa. Earth Sci. 2016, 5(3), 39-47. doi: 10.11648/j.earth.20160503.11

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AMA Style

Alain Tchakoutio Sandjon, Armand Nzeukou. On the Annual Variations in the Amplitude of 25-70-Day Intraseasonal Atmospheric Oscillations in Central Africa. Earth Sci. 2016;5(3):39-47. doi: 10.11648/j.earth.20160503.11

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@article{10.11648/j.earth.20160503.11,
  author = {Alain Tchakoutio Sandjon and Armand Nzeukou},
  title = {On the Annual Variations in the Amplitude of 25-70-Day Intraseasonal Atmospheric Oscillations in Central Africa},
  journal = {Earth Sciences},
  volume = {5},
  number = {3},
  pages = {39-47},
  doi = {10.11648/j.earth.20160503.11},
  url = {https://doi.org/10.11648/j.earth.20160503.11},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.earth.20160503.11},
  abstract = {In this paper we analyzed the annual variations in the 25-70-day intraseasonal atmospheric oscillations in central Africa, for the period 1981-2010, using the Outgoing Longwave OLR data. We then extracted the amplitude time series of the dominant modes of intraseasonal variability in 25-70 days filtered OLR anomalies, using Empirical Orthogonal Functions (EOF) analysis. The EOF analysis has shown that three dominant modes characterized the intraseasonal atmospheric oscillation in Central Africa. The amount of variance explained by these three retained EOFs are 19.3%, 13.6% and 11.8% respectively, and they exhibit higher spatial loading over Northern Congo, Southern Ethiopia, and Southwestern Tanzania, respectively. The analysis of Principal Components (PCs) time series showed that the amplitude and of the intraseasonal oscillations (ISO) exhibit large annual variations. In fact the highest values of ISO amplitude are generally observed during October-April season, and much weakened signal the rest of the year. The fraction of yearly Madden Julian Oscillation (MJO) power, occurring within October-April season are 79.3%, 77.92%, 78.73% for EOF1, EOF2, and EOF3, respectively.},
 year = {2016}
}

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TY  - JOUR
T1  - On the Annual Variations in the Amplitude of 25-70-Day Intraseasonal Atmospheric Oscillations in Central Africa
AU  - Alain Tchakoutio Sandjon
AU  - Armand Nzeukou
Y1  - 2016/07/23
PY  - 2016
N1  - https://doi.org/10.11648/j.earth.20160503.11
DO  - 10.11648/j.earth.20160503.11
T2  - Earth Sciences
JF  - Earth Sciences
JO  - Earth Sciences
SP  - 39
EP  - 47
PB  - Science Publishing Group
SN  - 2328-5982
UR  - https://doi.org/10.11648/j.earth.20160503.11
AB  - In this paper we analyzed the annual variations in the 25-70-day intraseasonal atmospheric oscillations in central Africa, for the period 1981-2010, using the Outgoing Longwave OLR data. We then extracted the amplitude time series of the dominant modes of intraseasonal variability in 25-70 days filtered OLR anomalies, using Empirical Orthogonal Functions (EOF) analysis. The EOF analysis has shown that three dominant modes characterized the intraseasonal atmospheric oscillation in Central Africa. The amount of variance explained by these three retained EOFs are 19.3%, 13.6% and 11.8% respectively, and they exhibit higher spatial loading over Northern Congo, Southern Ethiopia, and Southwestern Tanzania, respectively. The analysis of Principal Components (PCs) time series showed that the amplitude and of the intraseasonal oscillations (ISO) exhibit large annual variations. In fact the highest values of ISO amplitude are generally observed during October-April season, and much weakened signal the rest of the year. The fraction of yearly Madden Julian Oscillation (MJO) power, occurring within October-April season are 79.3%, 77.92%, 78.73% for EOF1, EOF2, and EOF3, respectively.
VL  - 5
IS  - 3
ER  -

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Author Information

Alain Tchakoutio Sandjon

Department of Computer Science, Higher Technical Teachers Training College (HTTTC), University of Buea, Kumba, Cameroon; Laboratory of Industrial Systems and Environmental Engineering, Fotso Victor Technology Institute, University of Dschang, Bandjoun, Cameroon; Laboratory for Environmental Modeling and Atmospheric Physics, Department of Physics, Faculty of Sciences, University of Yaoundé 1, Yaoundé, Cameroon
Armand Nzeukou

Laboratory of Industrial Systems and Environmental Engineering, Fotso Victor Technology Institute, University of Dschang, Bandjoun, Cameroon

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APA Style

Alain Tchakoutio Sandjon, Armand Nzeukou. (2016). On the Annual Variations in the Amplitude of 25-70-Day Intraseasonal Atmospheric Oscillations in Central Africa. Earth Sciences, 5(3), 39-47. https://doi.org/10.11648/j.earth.20160503.11

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ACS Style

Alain Tchakoutio Sandjon; Armand Nzeukou. On the Annual Variations in the Amplitude of 25-70-Day Intraseasonal Atmospheric Oscillations in Central Africa. Earth Sci. 2016, 5(3), 39-47. doi: 10.11648/j.earth.20160503.11

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AMA Style

Alain Tchakoutio Sandjon, Armand Nzeukou. On the Annual Variations in the Amplitude of 25-70-Day Intraseasonal Atmospheric Oscillations in Central Africa. Earth Sci. 2016;5(3):39-47. doi: 10.11648/j.earth.20160503.11

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@article{10.11648/j.earth.20160503.11,
  author = {Alain Tchakoutio Sandjon and Armand Nzeukou},
  title = {On the Annual Variations in the Amplitude of 25-70-Day Intraseasonal Atmospheric Oscillations in Central Africa},
  journal = {Earth Sciences},
  volume = {5},
  number = {3},
  pages = {39-47},
  doi = {10.11648/j.earth.20160503.11},
  url = {https://doi.org/10.11648/j.earth.20160503.11},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.earth.20160503.11},
  abstract = {In this paper we analyzed the annual variations in the 25-70-day intraseasonal atmospheric oscillations in central Africa, for the period 1981-2010, using the Outgoing Longwave OLR data. We then extracted the amplitude time series of the dominant modes of intraseasonal variability in 25-70 days filtered OLR anomalies, using Empirical Orthogonal Functions (EOF) analysis. The EOF analysis has shown that three dominant modes characterized the intraseasonal atmospheric oscillation in Central Africa. The amount of variance explained by these three retained EOFs are 19.3%, 13.6% and 11.8% respectively, and they exhibit higher spatial loading over Northern Congo, Southern Ethiopia, and Southwestern Tanzania, respectively. The analysis of Principal Components (PCs) time series showed that the amplitude and of the intraseasonal oscillations (ISO) exhibit large annual variations. In fact the highest values of ISO amplitude are generally observed during October-April season, and much weakened signal the rest of the year. The fraction of yearly Madden Julian Oscillation (MJO) power, occurring within October-April season are 79.3%, 77.92%, 78.73% for EOF1, EOF2, and EOF3, respectively.},
 year = {2016}
}

Copy | Download

TY  - JOUR
T1  - On the Annual Variations in the Amplitude of 25-70-Day Intraseasonal Atmospheric Oscillations in Central Africa
AU  - Alain Tchakoutio Sandjon
AU  - Armand Nzeukou
Y1  - 2016/07/23
PY  - 2016
N1  - https://doi.org/10.11648/j.earth.20160503.11
DO  - 10.11648/j.earth.20160503.11
T2  - Earth Sciences
JF  - Earth Sciences
JO  - Earth Sciences
SP  - 39
EP  - 47
PB  - Science Publishing Group
SN  - 2328-5982
UR  - https://doi.org/10.11648/j.earth.20160503.11
AB  - In this paper we analyzed the annual variations in the 25-70-day intraseasonal atmospheric oscillations in central Africa, for the period 1981-2010, using the Outgoing Longwave OLR data. We then extracted the amplitude time series of the dominant modes of intraseasonal variability in 25-70 days filtered OLR anomalies, using Empirical Orthogonal Functions (EOF) analysis. The EOF analysis has shown that three dominant modes characterized the intraseasonal atmospheric oscillation in Central Africa. The amount of variance explained by these three retained EOFs are 19.3%, 13.6% and 11.8% respectively, and they exhibit higher spatial loading over Northern Congo, Southern Ethiopia, and Southwestern Tanzania, respectively. The analysis of Principal Components (PCs) time series showed that the amplitude and of the intraseasonal oscillations (ISO) exhibit large annual variations. In fact the highest values of ISO amplitude are generally observed during October-April season, and much weakened signal the rest of the year. The fraction of yearly Madden Julian Oscillation (MJO) power, occurring within October-April season are 79.3%, 77.92%, 78.73% for EOF1, EOF2, and EOF3, respectively.
VL  - 5
IS  - 3
ER  -

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