Technical Report No. 118
James 0. Juvik, Paul C. Ekern
This study of the mountain cloud and fog regimes on the windward and leeward slopes of Mauna Loa, Hawai’i Island (1) develops a standardized louvered-screen, fog-catchment gage; (2) develops an indirect approximation method for estimating average droplet sizes during precipitation episodes and for separating the rainfall and fog components; (3) establishes an extensive fog sampling network on the windward and leeward slopes of Mauna Loa; and (4) develops an original computer program for detailed temporal and spatial analyses of rainfall, fog, and wind parameters.
An analysis of data for the 1974 to 1976 period yielded the following conclusions: (1) a well-defined fog belt exists on windward Mauna Loa in the altitudinal zone between 1500m to 2500m with fog catchment amounts as great as one-half the rainfall, or about 750m; (2) mountain fog on leeward Mauna Loa increases with elevation up to at least 2 000 m, with fog amounts equivalent to one-fourth the rainfall, or about 250 mm; (3) seasonal and altitudinal patterns in fog frequency and catchment amounts are related to the dynamic interaction of the tradewind field (particularly the tradewind inversion), the local land/sea breeze regime, and rainfall; (4) mountain fog appears to be a significant factor in the water balance of mountain ecosystems on Mauna Loa; and (5) the potential for large-scale mechanical recovery of fog water may exist for selected locations on Mauna Loa.