Bivariate and Partial Wavelet Coherence analysis of aerosols impact on Global Horizontal Irradiation in Far-North and Littoral regions of Cameroon


  • Yaulande Douanla Alotse Physics, Institute of Mathematics and Physics (IMSP), Dangbo, B´enin
  • Mamadou Ossénatou Physics, Institute of Mathematics and Physics (IMSP), Dangbo, B´enin
  • Dembele André Operations Research and Optimization, Department of Mathematics and Informatics, Faculty of Sciences and Technics (FST), Mali
  • Lenouo André Laboratory of Physics, University of Douala, Cameroon


Irradiation, Biwavelet, Partial wavelet coherence, Aerosols, Cameroon


This study investigated the time-frequency variability of Global Horizontal Irradiation (GHI) under clear sky conditions in Cameroon in relation to aerosol types using the wavelet transform method. For this purpose, we focused on two climatically different zones (Far North and Littoral) in Cameroon chosen because of the large difference in term of proportion in type of aerosols. From the Bivariate Wavelet Coherence (BWC) analysis, it was found in the Littoral zone (Dust DU, Organic Matter OM, Black Carbon BC, Sulfates SU) aerosols are negatively correlated with GHI at all frequencies, whereas Sea Salt (SS) aerosols are positively correlated with GHI. In the Far North zone, all aerosols are negatively correlated with GHI in the 0-8 month band but the dynamic has changed in the 8-16 month band. However, with the Partial Wavelet Coherence (PWC) analysis, we found that the correlations between GHI and each analyzed variable decreased after removing the effects of the remaining variables. Only the correlations between GHI and DU are still significant, with an average wavelet coherence (AWC) and percentage of significant coherence (PASC) values of 0.60 and 24.36% respectively. It is noteworthy with PWC analysis that the area with significant correlation between GHI and the other aerosol types except DU is very limited. This shows that their influences on GHI have already been covered by DU. The study also showed the combined effect of the analyzing variables (SS, BC, SU and OM) on GHI, since, independently as shown by the PWC, each of them is weakly correlated to GHI. However, with the BWC, the combined effect of other aerosols on BC and SU makes their influences on GHI important. The PWC and BWC implementations have been compiled by Matlab and can be accessed freely following this link (


M. Okono, E. Agbo, B. Ekah, U. Ekah, E. Ettah & C. Edet, “Statistical analysis and distribution of global solar radiation and temperature over southern Nigeria”, Journal of the Nigerian Society of Physical Sciences 4 (2022) 588.

A. S. Khalil, “Performance Evaluation and Statistical Analysis of Solar Energy Modeling: A Review and Case Study”, Journal of the Nigerian Society of Physical Sciences, 4 (2022) 911.

M. Matt & R. Babcock, “Renewable Energy Debate”, CQ Researcher, book item 114665.pdf, (2019).

H. Sybille, N. Kai & A. Simone, “Renewable energy resources: how can science education foster an appropriate understanding?”, European Science Education Research Association (2018).

O. P. Asantewaa & A. Samuel, “A review of renewable energy sources, sustainability issues and climate change mitigation”, Cogent Engineering 3 (2016) 1167990.

G. Dolf, B. Francisco, S. Deger, B. Morgan, W. Nicholas & G. Ricardo, “The role of renewable energy in the global energy transformation”, Energy Strategy Reviews, 24 (2019) 38.

D. U. Chandra, K. G. Panagiotis, N. S. Shantikumar & M. Akriti, “Impact of aerosol and cloud on the solar energy potential over the central gangetic himalayan region”, Remote Sensing 13 (2021) 3248.

D. Yang, J. Panida & W. Wilfred M, “The estimation of clear sky global horizontal irradiance at the equator”, Energy Procedia 25 (2012) 141.

E. A. Omaima, G. Hicham, G. Abdellatif & D. Fatima-ezzahra, “Detection of clear sky instants from high frequencies pyranometric measurements of global horizontal irradiance”, E3S Web of Conferences 229 (2021) 01008.

Z. Guang & M. Yingying, “Clear-Sky Surface Solar Radiation and the Radiative Effect of Aerosol and Water Vapor Based on Simulations and Satellite Observations over Northern China”, Remote Sensing 12, (2020) 1931.

Z. Evans, “Predicting clear-sky global horizontal irradiance at eight locations in South Africa using four models”, Journal of Energy in Southern Africa 28 (2017) 77.

F. Ilias et al., “Effects of aerosols and clouds on the levels of surface solar radiation and solar energy in Cyprus”, Remote Sensing 13 (2021) 2319.

X. Weipeng, Z. Guangyuan & P. Stefan, “Estimation of global horizontal irradiance in China using a deep learning method”, International Journal of Remote Sensing 42 (2021) 3899.

G. Emily, T. Velle, N. K. Pagh, R.Laura & M. J´an, “E ects of aerosols on clear-sky solar radiation in the ALADIN-HIRLAM NWP system”, Atmospheric Chemistry and Physics 16 (2016) 5933.

Y. Liwei, G. Xiaoqing, L. Zhenchao & J. Dongyu, “Quantitative effects of air pollution on regional daily global and diffuse solar radiation under clear sky conditions”, Energy Reports 8 (2022) 1935.

P. Kyriakoula, F. Ilias, G. Antonis, K. G. Panagiotis, N. T. Panagiotis, Ha. Maria & K. Stelios, “15-Year Analysis of Direct Effects of Total and Dust Aerosols in Solar Radiation/Energy over the Mediterranean Basin”, Remote Sensing 14 (2022) 1535.

Y. A. Douanla, A. Demb´el´e, O. Mamadou & A. Lenouo, “Prediction of daily direct solar energy based on XGBoost in Cameroon and key parameter impacts analysis”, 2022 IEEE Multi-conference on Natural and Engineering Sciences for Sahel’s Sustainable Development (MNE3SD) (2022) 1.

Y. A. Douanla, A. Demb´el´e, O. Mamadou, D. R. R. Koukoui, F. E. Akpoly & A. Lenouo, “Wavelet Analysis of the Interconnection between Atmospheric Aerosol Types and Direct Irradiation over Cameroon”, Advances in Meteorology (2022).

P. B. Donald & W. T. Andrew, Wavelet methods for time series analysis, Cambridge university press 4 (2000).

S. Jevrejeva, JC. Moore & A. Grinsted, “Influence of the Arctic Oscillation and El Ni˜no-Southern Oscillation (ENSO) on ice conditions in the Baltic Sea: The wavelet approach”, Journal of Geophysical Research: Atmospheres, 108 (2003) D21.

C. Pimwadee, G. Aryya, K. George & C. Zhiyuan, “Discrete wavelet transform-based time series analysis and mining”, ACM Computing Surveys (CSUR) 43 (2011) 1.

T. B. Godfrey, “Cameroon 55”, Handbook of Global Bioethics, (2014) 941.

P. Tchawa, “Le Cameroun: une Afrique en miniature?”, Les Cahiers d’Outre-Mer. Revue de g´eographie de Bordeaux 65 (2012) 319.

G. Aslak, J. C. Moore & S. Jevrejeva, “Application of the cross wavelet transform and wavelet coherence to geophysical time series”, Nonlinear processes in geophysics 11 (2004) 561.

K. Ladislav, “What are the main drivers of the Bitcoin price? Evidence from wavelet coherence analysis”, PloS one 10 (2015) e0123923.

J. Bitton et al., ´ecosyst`eme forestier et l’atmosph`ere au moyen de la transform´ee en ondelettes continue, Universit´e de Li`ege, Li`ege, Belgique (2019).

E. KW . Ng & J. CL. Chan, “Geophysical applications of partial wavelet coherence and multiple wavelet coherence”, Journal of Atmospheric and Oceanic Technology 29 (2012) 1845.

C. Lara, B. Cazelles, G. S. Sald´?as, R. P. Flores, A´ . L. Paredes & B. R. Broitman, “Coupled biospheric synchrony of the coastal temperate ecosystem in Northern Patagonia: a remote sensing analysis”, Remote Sensing 11 (2019) 2092.

C. Torrence & G. P. Compo, “A practical guide to wavelet analysis”, Bulletin of the American Meteorological society 79 (1998) 1.

H. Wei, Matlab code for multiple wavelet coherence and partial wavelet coherency, code for multiple wavelet coherence and partial wavelet coherency/13031123/2, (2020).

H. Wei & S. Bing, “Improved partial wavelet coherency for understanding scale-specific and localized bivariate relationships in geosciences”, Hydrology and Earth System Sciences 25 (2021).

C. McSweeney, M. New & G. Lizcano, UNDP climate change country profiles: Cameroon (2008), reports/Cameroon/, Oxford: United Nations Development Programme and University of Oxford.

K. Matsuda, S. Nakae & K. Miura, “Origin and characteristics of sulfate aerosols in Tokyo”, Journal of Japan Society for Atmospheric Environment /Taiki Kankyo Gakkaishi 33 (1998) 4.

C. Liousse et al., “Real time black carbon measurements in West and Central Africa urban sites”, Atmospheric Environment 54 (2012) 529.

P. PXiaole, Y. Kanaya & Z. Wang, “Correlation of black carbon aerosol and carbon monoxide in the high-altitude environment of Mt. Huang in eastern China”, AGU Fall Meeting Abstracts (2011) A21B–0034.

D. Fonkem et al. “Effects of season on the microbiological quality of Kilishi, a traditional Cameroonian dried beef product”, Tropicultura 28 (2010) 10.



How to Cite

Bivariate and Partial Wavelet Coherence analysis of aerosols impact on Global Horizontal Irradiation in Far-North and Littoral regions of Cameroon. (2023). Journal of the Nigerian Society of Physical Sciences, 5(1), 1248.



Special Issue : 3rd biennial AScIN conference OAU,  Nigeria

How to Cite

Bivariate and Partial Wavelet Coherence analysis of aerosols impact on Global Horizontal Irradiation in Far-North and Littoral regions of Cameroon. (2023). Journal of the Nigerian Society of Physical Sciences, 5(1), 1248.