Atmospheric Forcing of the Winter Air–Sea Heat Fluxes over the Northern Red Sea

Abstract

The influence of the atmospheric circulation on the winter air-sea heat fluxes over the northern Red Sea is investigated during the period 1985-2011. The analysis based on daily heat flux values reveals that most of the net surface heat exchange variability depends on the behavior of the turbulent components of the surface flux (the sum of the latent and sensible heat). The large-scale composite sea level pressure (SLP) maps corresponding to turbulent flux minima and maxima show distinct atmospheric circulation patterns associated with each case. In general, extreme heat loss (with turbulent flux lower than 2400 W m 22) over the northern Red Sea is observed when anticyclonic conditions prevail over an area extending from the Mediterranean Sea to eastern Asia along with a recession of the equatorial African lows system. Subcenters of high pressure associated with this pattern generate the required steep SLP gradient that enhances the wind magnitude and transfers cold and dry air masses from higher latitudes. Conversely, turbulent flux maxima (heat loss minimization with values from 2100 to 250 W m 22) are associated with prevailing low pressures over the eastern Mediterranean and an extended equatorial African low that reaches the southern part of the Red Sea. In this case, a smooth SLP field over the northern Red Sea results in weak winds over the area that in turn reduce the surface heat loss. At the same time, southerlies blowing along the main axis of the Red Sea transfer warm and humid air northward, favoring heat flux maxima.

Multi-decadal classification of synoptic weather types, observed trends and links to rainfall characteristics over Saudi Arabia

“…These depressions originally develop in the North Atlantic Ocean and the central Mediterranean and then move to the east, enhanced by the deepening upper level trough and the lee-low effect of the Cyprus mountains (Almazroui, 2006). Papadopoulos et al (2013) indicated that the low pressure originating over both the east Mediterranean and equatorial Africa shifts during winter to be placed over the Red Sea. According to Cullen et al (2002) and Kahya (2011), the winter cyclones over the Middle East region are significantly impacted not only by changes in the Atlantic westerly heat/moisture transport controlled by the NAO, but also by changes in sea surface temperatures (SSTs) between the Atlantic and the Mediterranean.…”

Regional Hydrological Cycle over the Red Sea in ERA-Interim

“…1a (Papadopoulos et al 2013;Abualnaja et al 2015) as well as with other modern-era reanalyses, such as MERRA (Abualnaja et al 2015). The climatological maximum of annual precipitation (Fig.…”

“…The Red Sea is a unique basin characterized by extremely high evaporation, which amounts to 1.6-1.9 m yr 21 for the whole sea (Tragou et al 1999) and may increase to more than 3 m yr 21 in the northern part (e.g., Papadopoulos et al 2013). Upon rising into the atmosphere, this moisture participates in the regional hydrological cycle, influencing water content and precipitation over the adjacent continents.…”

“…Spinks and Lin (2015) and Spinks et al (2015) demonstrated that, in summer, the Arabian high may contribute to the intensification of the local winds and to the westward propagation of the easterly waves and that this effect has intensified over recent decades. Large-scale circulation modes (the NAO and Indian monsoon) can influence air-sea exchanges over the Red Sea (Papadopoulos et al 2013;Abualnaja et al 2015). As a diabatic source of heat and moisture, the Red Sea contributes to the generation of local circulation patterns, such as the Red Sea Trough (Krichak et al 2012), that are associated with abundant precipitation in northeastern Africa.…”

“…The leading EOFs (44% of explained variance for JFM and 32% for JAS) imply intensification/deintensification of the transports associated with the Arabian high and its south-to-north shifts. Papadopoulos et al (2013) and Abualnaja et al (2015) argued that these changes are likely dominated by the North Atlantic-European circulation pattern. The corresponding normalized PCs (Figs.…”