Articles online

The Contribution of Large-scale Atmospheric Patterns to Pollution With PM10: The New Saharan Oscillation Index

Category: Urban Air Quality

Accepted Manuscripts
DOI: 10.4209/aaqr.2019.08.0401

Export Citation:  RIS | BibTeX

To cite this article:
Khomsi, K., Najmi, H., Chelhaoui, Y. and Souhaili, Z. (2020). The Contribution of Large-scale Atmospheric Patterns to Pollution With PM10: The New Saharan Oscillation Index. Aerosol Air Qual. Res., doi: 10.4209/aaqr.2019.08.0401.

Kenza Khomsi 1,2, Houda Najmi1, Youssef Chelhaoui1, Zineb Souhaili2

  • 1 Direction de la Météorologie Nationale, Boulevard Mohamed Tayeb Naciri, Hay Hassani B.P. 8106 Oasis-Casablanca, Morocco
  • 2 Laboratory of Drugs Science, Biomedical and Biotechnological Research. Faculty of Medicine and Pharmacy. Hassan II University; Ain Chock., Casablanca; P.B. 5696, Morocco


  • The Mediterranean Oscillation (MO) plays a major role in particle pollution.
  • A new oscillation may be defined: The Saharan Oscillation (SaO).
  • Particle pollution worldwide may be triggered by the SO and controlled by the MO.
  • A new relevant index may be defined: the Saharan Oscillation Index (SaOI).
  • Computed SaOI is statistically related with PM10 and NAO and MO indexes.


PM10 has natural and anthropogenic sources, it is an urban air pollutant from desertic areas or emitted by industry and traffic activities, it reduces visibility and threatens human wellbeing mainly in big cities.

Casablanca concentrates many industrial units and a large vehicle fleet. The rate of urbanization in the metropolis and the population density are the highest in Morocco. Marrakech is one of the most populated cities in the country where the motorization rate has increased during recent years.

The present work is based on PM10 daily measurements between 2013 and 2016. The main objective is to assess the concentrations of PM10 in Casablanca and Marrakech and study their relationship with the atmospheric circulation. First, we assessed PM10 correlations with climate indexes (the North Atlantic Oscillation (NAO) and the Mediterranean Oscillation (MO)), then we characterized the contribution of large-scale atmospheric patterns related to PM10 extreme events. The novelty of this research is the creation of a new climate index to characterize the oscillation, in the country’s southern desert, between the Saharan depression and the Azores high. The time series of the new Saharan Oscillation Index (SaOI) were calculated.

This study has demonstrated the relationship between MO and PM10 averages and has shown that particulate pollution in the study area is partly induced by continental northeasterly to southwesterly flow. This flow is triggered by the Saharan trough and managed by the high-pressure area in the north. The assessed correlations related to the SaOI confirm the relationship between this index, PM10 averages, and MO and NAO indexes mainly in winter.


Particulate Matter (PM10) Correlation Saharan Depression Climate Index Saharan Oscillation Index (SaOI) Air Quality

Related Article

Particle Mass Concentrations and Number Size Distributions in 40 Homes in Germany: Indoor-to-outdoor Relationships, Diurnal and Seasonal Variation

Jiangyue Zhao, Wolfram Birmili, Birgit Wehner, Anja Daniels, Kay Weinhold, Lina Wang, Maik Merkel, Simonas Kecorius, Thomas Tuch, Ulrich Franck, Tareq Hussein, Alfred Wiedensohler

A Comparison Study of Indoor and Outdoor Air Quality in Nanjing, China

Ruochong Xu, Ximeng Qi , Guoqing Dai, Haoxian Lin, Jiachun Shi, Chengxu Tong, Peng Zhai, Caijun Zhu, Lei Wang, Aijun Ding
Accepted Manuscripts
DOI: 10.4209/aaqr.2019.10.0496

Spatiotemporal Variations and Contributing Factors of Air Pollutants in Almaty, Kazakhstan

Aiymgul Kerimray , Eldar Azbanbayev, Bulat Kenessov, Pavel Plotitsyn, Danara Alimbayeva, Ferhat Karaca
Article In Press
DOI: 10.4209/aaqr.2019.09.0464