Lomas formations in southern Peru are related to moisture availability due to frequent incursions of fog in austral winter. Due to warming of coastal waters of southern Peru during El Ni？o, lomas formations are enhanced via greater moisture availability for fog and drizzle. Our study evaluates the modern climatological record in austral winter to determine if there are differences in moisture availability between El Ni？o and La Ni？a for fog formation. Our results show anomalous northwesterly onshore flow, warmer than normal sea-surface temperatures, and an increase in precipitable water in El Ni？o, favoring lomas formations due to advection fog with higher moisture content. On the other hand, La Ni？a also favors frequent advection fog, with less moisture content due to strong onshore flow over relatively cool SSTs. Since lomas may represent fragments of a continuous vegetation belt that existed during the Pliocene, a permanent El Ni？o favoring vigorous vegetation production along the south Peruvian coast due to incursions of fog with high precipitable water may have occurred in this period. However, the possibility of normal El Ni？o variability superimposed on a warmer climatology producing fog with higher moisture content in both El Ni？o and La Ni？a conditions cannot be discounted. 1. Introduction An aspect of the local climate in the arid, coastal regions of southern Peru is the appearance of vegetation oasis areas known as lomas [1–3]. The modern-day existence of lomas may represent remnants of a continuous vegetation belt along the coast of South America during the Pliocene (e.g., [4]). The existence of lomas is tied to advective fog from the South Pacific [5]. An increase in vegetation in lomas areas may be related to greater water availability for fog during El Ni？o (e.g., [6, 7]). Paradoxically, Manrique et al. [7] indicate that despite a lower frequency of fog during El Ni？o, a greater amount of fog and water collection occurred over southern Peru and northern Chile during the 1997-1998 El Ni？o [8]. Manrique et al. [7] further state that it was not possible to separate increases in water content due to austral summer drizzle from austral winter fog. However, Manrique et al. [7] suggest that El Ni？o induced precipitation increases in austral summer may be a short-term response. Therefore, long-term climate response of lomas formation due to El Ni？o may be due to greater moisture availability from fog advecting from warmer sea-surface temperature (SST) windward of the coast of southern Peru. Given the potential linkage of enhanced lomas formation
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