Abstract/Summary

This investigation presents a new high-resolution mineral dust climatology for the Middle East, describing the dust emission source of over 27,000 dust emission events during the period 2006 – 2013. The inventory was derived from the dust RGB product of the Spinning Enhanced Visual and InfraRed Imager (SEVIRI) on-board Meteosat’s second-generation satellite (MSG). Mineral dust emissions were derived from visual inspection of the SEVIRI scenes, which have 4-5 km2 spatial and 15-minute temporal resolution. The location of every emission event was recorded in a database, along with time and trajectory of dust movement. This is an improvement on previous studies, which derive dust source areas from the daily observations of Aerosol Optical Depth whose maxima do not necessarily coincide with sources of emissions, producing more accurate information on the location of the important dust sources in the region. Results showed that dust sources are constrained to relatively small areas, with 23% of dust emissions generated from areas covering just 1% of the total land surface of the Middle East. Important sources include the Tigris-Euphrates flood plains of Iraq and Syria, Western and Northern Saudi Arabia and the Sistan Basin in Eastern Iran. The Tigris-Euphrates flood plain was the most active dust region, producing 37% of all dust events. Here, agricultural surfaces, especially those producing rain-fed wheat and barley appear to be particularly sensitive to drought conditions, with greatest dust emission frequency at the peak of the 2007 – 2009 drought – the most severe drought in instrumental history. Normalised Difference Vegetation Index (NDVI) data was acquired from the Moderate Resolution Imaging Spectrodiometer (MODIS) (MOD13A2) 1km database and correlated with dust emission frequency data in the region of greatest dust activity. These dust emission ‘hotspots’ showed a significant correlation between vegetation cover and dust emission frequency, with increased vegetation cover during non-drought years producing a marked decrease in dust emission frequency. The southern areas of the Arabian Peninsula recorded very few dust emission observations, contrasting directly to many previous studies, which do not use such high temporal resolution data. The activation and frequency of dust emissions are characterised by strong seasonality developing in response to specific synoptic conditions. ERA Interim reanalysis data were used to characterise synoptic conditions on identified dusty days, demonstrating a concurrent increase in dust emission frequency with intensifying summer (JJA) Shamal (northerly) winds over the Arabian Peninsula.