Consequences of DESERTification for the radiaTive Impact of atmospheric dust over the Middle East (DESERT-TIME)

• Applicant: Dr. Jamie Banks
• Subject Area: Atmospheric Science
• Term: from 2018 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 414044717

Droughts in the Middle East over recent decades have had serious consequences for water and food security, threatening the health and livelihoods of millions of people in the region. As croplands and other vegetated areas become drier, desertification causes crop failure and leaves land exposed to the spread of neighbouring deserts. Dry, exposed soil is vulnerable to being blown off the surface by strong winds, and so dust storms are a common feature of desert environments. If deserts spread, then it is to be expected that so too would dust storms become more frequent and more intense, which can degrade the quality of the air and be harmful to human health.Atmospheric dust also affects the Earth’s thermostat, by influencing the warming or cooling of the environment. When a dust storm passes over a region, it will reflect light from the Sun, and so it will tend to cool the Earth’s surface. On the other hand, the dust will also absorb some of this incoming light from the Sun, and so dust may warm the Earth’s atmosphere. However, this warming will occur mostly in the vicinity of the dust layer, so the altitude of the dust influences the warming or cooling of the Earth’s atmosphere.Various questions therefore emerge as to the impact of desertification on the Middle Eastern environment:1) To what extent have recent droughts increased the spread of dust storms in the region? Dust storms have been observed to have increased in frequency, but what has been the increase in their quantity? Dust transport models can provide precise answers to these questions by simulating the differences in dust activity between various scenarios: in this case, simulations will be performed using ‘non-drought’ and drier ‘drought’ scenarios, representing the differences in the vegetation and soil between the two cases. The hypothesis is that the latter scenario will produce more frequent and more intense dust events, and the simulations will calculate the extent to which this is the case.2) How has this change in dust activity affected the influence of dust on the warming or cooling of the Earth’s surface and atmosphere? These effects will be calculated under both conditions of non-drought and drought, so that the differences can be analysed. Measurements made at the surface and from satellites will also be used, in order to enhance our understanding of the environmental influences on these effects.3) To what extent is this change in dust activity measurable from regional satellite data? Satellite measurements will be compared with the simulations in order to show which drought scenario more accurately represents the observed behaviour of dust in the atmosphere. This will also provide further insights as to the ability to infer from the satellite measurements the warming or cooling of the atmosphere due to dust.Asking and answering these questions will provide further insights into the effects of Middle Eastern desertification and dust on the atmospheric environment.

• DFG Programme: Research Grants