Atmospheric Rivers Bring Floods and Dust to the Middle East

ABSTRACT:

Some of the hydro-meteorological extreme events are caused by Atmospheric Rivers (ARs),defined as “long, narrow, and transient corridors of strong horizontal water vapor transport”. While extensive research has examined the impacts of ARs on weather-related disasters acrossthe western U.S. and Europe, little is known about their mechanisms in the Middle East. In this talk, I will discuss two ARs that led to unprecedented precipitation/flooding across the region and caused widespread damages and casualties, particularly in Iran. Both ARs were located along a cold front associated with a mid-latitude cyclone and fed by moisture from the Mediterranean and Red Seas, though one was also connected to the Atlantic Ocean through a subtropical jet. The ARs can carry massive amounts of water vapor. For example, moisture transport by one of these ARs was equivalent to more than 150 times the aggregated flow of the four major rivers in the region. In addition to their role in flooding, these ARs generated anomalous dust transport due to their strong winds. This is a unique characteristic of the Middle Eastern ARs, which propagate over major sources of mineral dust. Using NASA’s GEOS model, we showed that these events could be reasonably predicted at 5 to 7-day leads. Skillful prediction of such high-impact weather extremes would be crucial for decision makers, especially in climatically vulnerable regions.

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