Influences of synoptic situation and teleconnections on fog-water collection in the Mediterranean Iberian Peninsula, 2003–2012

Abstract

Fog-water collection has been widely analysed for its quantification and potential uses; however, there are few studies assessing the synoptic conditions and large-scale teleconnection patterns that affect its occurrence. Focusing on the Mediterranean Iberian Peninsula, this work aims to analyse the synoptic patterns, both at surface level and 850 hPa geopotential height, that most likely to favour fog-water collection, and to quantify the relationship between fog-water collection and the NAOi (North Atlantic Oscillation index), MOi (Mediterranean Oscillation index) as well as WeMOi (Western Mediterranean Oscillation index) teleconnection patterns. For this purpose, daily fog-water observations from a dense network of 23 fog-water collectors located along the Mediterranean Iberian Peninsula for 2003–2012 were analysed in relation to synoptic patterns and the three-teleconnection indices. The major findings are: (a) The most favourable synoptic patterns for fog-water collection are maritime advections carrying humidity from the Mediterranean basin, and cyclonic circulations, whereas anti-cyclonic situations generally led to large number of foggy days with low fog-collection rates. (b) In terms of winds at 850 hPa, the most favourable low-level flows for fog-water collection are associated with strong winds (>5.1 m s) from the Mediterranean. Atlantic winds generally cause a greater number of fog days than Mediterranean winds, with less fog-water collection rates. (c) WeMOi has the greatest influence on fog-water collection, mainly during winter and spring months, with statistically significant negative relationships for most of the stations. MOi also shows a great influence, with a large number of statistically significant negative correlations, mainly during the same months as WeMOi. Lastly, NAOi presented the lowest and no significant negative correlations with fog-water collection.