Comment on esd-2022-10

Abstract

Extreme precipitation events and associated flash floods caued by the synoptic cyclonic-systems have profound impacts on society and the environment particularly in dry regions. This study brings forward a satellite-reanalysis-based approach to quantify the extreme precipitation characteristics over the Sinai Desert in Egypt, from a statistical-synoptic perspective for the period of 2001–2020. Using the satellite remote-sensing precipitation and a set of climate indices, we characterize the spatiotemporal distribution of extreme rainfall climatologies across the Sinai region. Then, using the reanalysis dataset, the synoptic systems responsible for the occurrence of precipitation events along with the major tracks of cyclones during the wet and dry periods are explored. Our results indicate that the temporal changes and spatial patterns of the precipitation events do not show a homogenous tendency, rather lack of spatiotemporal coherence across the Sinai. Northern parts of the Sinai, unlike other areas, exhibit the highest anomalies (approx. ±45 mm/decade); and the annual rainfall trends indicate a drier-climate in the north at −0.03 mm/decade, while a wetter-climate is observed in the central and southern parts at 0.10 and 0.36 mm/decade, respectively. The Mediterranean cyclones accompanied by the Red Sea -and Persian Troughs are responsible for the majority of extreme rainfall events all-round the year. A remarkable spatial relationship between the Sinai’s rainfall and the atmospheric variables of sea level pressure, wind direction and vertical velocity is found. Furthermore, the cyclone-tracking analysis indicates that 125 and 31 cyclones (rainfall ≥ 10mm/day) either formed within -or transferred to the Mediterranean basin and precipitated over the Sinai during wet and dry periods, respectively; while some (~15 % with rainfall > 40mm/day) being capable of leading to flash flood in the wet period of the region. This study, therefore, sheds new light on the extreme rainfall characteristics and the dominant synoptic mechanisms over the Sinai region in the eastern Mediterranean basin.