Articles | Volume 16, issue 21
Atmos. Chem. Phys., 16, 13431–13448, 2016
Atmos. Chem. Phys., 16, 13431–13448, 2016

Research article 31 Oct 2016

Research article | 31 Oct 2016

The impact of the Pacific Decadal Oscillation on springtime dust activity in Syria

Bing Pu1,2 and Paul Ginoux1,2 Bing Pu and Paul Ginoux
  • 1Atmospheric and Oceanic Sciences Program, Princeton University, Princeton, New Jersey 08544, USA
  • 2NOAA Geophysical Fluid Dynamics Laboratory, Princeton, New Jersey 08540, USA

Abstract. The increasing trend of aerosol optical depth in the Middle East and a recent severe dust storm in Syria have raised questions as to whether dust storms will increase and promoted investigations on the dust activities driven by the natural climate variability underlying the ongoing human perturbations such as the Syrian civil war. This study examined the influences of the Pacific Decadal Oscillation (PDO) on dust activities in Syria using an innovative dust optical depth (DOD) dataset derived from Moderate Resolution Imaging Spectroradiometer (MODIS) Deep Blue aerosol products. A significantly negative correlation is found between the Syrian DOD and the PDO in spring from 2003 to 2015. High DOD in spring is associated with lower geopotential height over the Middle East, Europe, and North Africa, accompanied by near-surface anomalous westerly winds over the Mediterranean basin and southerly winds over the eastern Arabian Peninsula. These large-scale patterns promote the formation of the cyclones over the Middle East to trigger dust storms and also facilitate the transport of dust from North Africa, Iraq, and Saudi Arabia to Syria, where the transported dust dominates the seasonal mean DOD in spring. A negative PDO not only creates circulation anomalies favorable to high DOD in Syria but also suppresses precipitation in dust source regions over the eastern and southern Arabian Peninsula and northeastern Africa.

On the daily scale, in addition to the favorable large-scale condition associated with a negative PDO, enhanced atmospheric instability in Syria (associated with increased precipitation in Turkey and northern Syria) is also critical for the development of strong springtime dust storms in Syria.

Short summary
Dust aerosols play an important role in the climate system. Strong dust storms also have severe social and health impacts. The 2015 severe dust storm in Syria raised concerns as to whether dust activities will increase in the region. The first step toward answering this question is to understand the dust activities driven by the natural climate variability. This work found that the Pacific Decadal Oscillation plays a dominant role in springtime dust activities in Syria in the recent decade.
Final-revised paper