The Imprint of the Southern Annular Mode on Black Carbon AOD in the Western Cape Province

Atmosphere

Heiko Paeth¹  Chibuike Chiedozie Ibebuchi¹ 

[1] Institute of Geography and Geology, University of Würzburg, Am Hubland, 97074 Würzburg, Germany;

关键词: black carbon AOD;    Western Cape;    southern annular mode;    circulation type;    air quality;   

DOI  :  10.3390/atmos12101287

来源: DOAJ

【 摘 要 】

This study examines the relationship between variations of the Southern Annular Mode (SAM) and black carbon (BC) at 550 nm aerosol optical depth (AOD) in the Western Cape province (WC). Variations of the positive (negative) phase of the SAM are found to be related to regional circulation types (CTs) in southern Africa, associated with suppressed (enhanced) westerly wind over the WC through the southward (northward) migration of Southern Hemisphere mid-latitude cyclones. The CTs related to positive (negative) SAM anomalies induce stable (unstable) atmospheric conditions over the southwestern regions of the WC, especially during the austral winter and autumn seasons. Through the control of CTs, positive (negative) SAM phases tend to contribute to the build-up (dispersion and dilution) of BC in the study region because they imply dry (wet) conditions which favor the build-up (washing out) of pollutant particles in the atmosphere. Indeed, recent years with an above-average frequency of CTs related to positive (negative) SAM anomalies are associated with a high (low) BC AOD over southwesternmost Africa.

【 授权许可】

Unknown