Pilar Cereceda

A Proposed Standard Fog Collector for Use in High-Elevation Regions

Abstract The collection of fog droplets by vegetation is an important wet deposition process. It can, in fact, dominate the chemical and hydrological input to certain high elevation watersheds. However, measurements of fog deposition are rarely made and, where they do exist, comparisons of deposition rates in different locations have been hampered by the use of innumerable types of collection devices. A simple, inexpensive, 1-m2 fog collector that can produce measurements of the deposition of fog water to a vertical surface is described here. The collector has been used successfully in five countries to investigate the variation of fog deposition in complex terrain and to estimate the deposition to trees and to much larger fog collectors. It is proposed that it be employed widely as a standard to quantify the importance of fog deposition to forested high elevation areas and to measure the potential collection rates in denuded or desert mountain ranges. The standard fog collector costs about the same as a ...

The Quality of Fog Water Collected for Domestic and Agricultural Use in Chile

Abstract One exciting new application of meteorology is the prospect of using high-elevation fogs as an and lands water resource. This has now become reality in northern Chile where a pilot project has used 50 fog collectors to generate an average of 7200 1 of water per day during three drought years. The chemical composition of the fog water is of primary importance and is examined in this paper. A small, carefully cleaned fog-water collector was used at the site (elevation 780 m) to study the incoming fog (cloud). The ion and trace-element concentrations met Chilean and the World Health Organizations (WHO) drinking-water standards. The pH values, however, were at times extremely low. Samples from 1987 and 1988 were consistent with those from the larger dataset in 1989. The lowest observed pH was 3.46. The acidity was associated with high concentrations (89%) of excess sulfate in the 15 fog-water samples (based on Cl− as the seawater tracer element). The NO3−/SO4− equivalents ratio for the fog samples ...

The Occurrence of Fog in Chile

Abstract The topography in Chile is extremely complex and many types of fog are found; both factors complicate the presentation of the data. Despite this, measurements from standard meteorological stations suggest a latitudinal maximum in fog frequency between 35° and 40°S for coastal stations. This is supported by data from inland stations in Chile and the available observations from Argentina on the Atlantic coast of South America. Along the Chilean coast the average number of days with fog ranges from 3 to 59 per year. The variation in fog frequencies is related to persistent synoptic-scale circulation patterns and to ocean currents. Specialized fog observations wore made at three remote locations in northern Chile to determine fog frequencies on the coastal mountains. The sites were in a very add region (26°–28°S) near a large-scale fog-water collection project. Fog frequencies as high as 189 days per year with another 84 days of patchy fog were reported at an altitude of 860 m. These are 3–15 times h...

A NEGLECTED WATER-RESOURCE - THE CAMANCHACA OF SOUTH-AMERICA

Abstract Many parts of the world are currently suffering water shortages. Few areas, however, have as little precipitation and groundwater available to alleviate the problem as does the northern coast of Chile. The historical background of the attempts to collect water directly from the coastal stratocumulus decks is reviewed in this paper as are the meteorological and geographical considerations important to the collection of the cloud water. Calculations of water availability and cost indicate that this may well be an important source of water for some coastal regions. A combined research and applied project to study the properties of high-elevation fogs and their use as a water supply will be conducted by Chilean and Canadian agencies from late 1987 to the end of 1988.

Fog measurements at the site “Falda Verde” north of Chañaral compared with other fog stations of Chile

Fog collection data registered through a Standard Fog Collector (SFC) installed by a local fishermens association at a height of 600 m at the “Falda Verde” site, north of the Chilean harbor Chanaral (26°17′S/70°36′W), from November 1998 to November 2000, are analyzed. Trying to give new lights on the dynamics of fog along the Chilean northern coast, this article compares, for the first time, the data obtained at Falda Verde with those obtained at five other Chilean fog stations. The total time period runs from 1987 to 2001. A mean of 1.46 l/m2/day was registered at the Falda Verde site after 2 years of measurements, one of the lowest yields along the north Chilean coast. After a brief historical recapitulation of fog researches in the study area, geographical explanations of the water yields obtained in different sites are discussed. The annual mean collection from Cerro Moreno and Paposo shows a clearly different behavior from all other sites, showing a greater stability throughout the year. Other stations have a marked difference between extreme seasons. Alto Patache yields, if not the best in Chile, are very high and offer unexpected possibilities for future applications in the coast. Stations located away from the seashore (Cerro Guatalaya) are clearly less productive. Ocean proximity, altitude, south and southwest orientations of the coastal ranges and local relief explain some of the differences noted.

Monsoon cloudwater chemistry on the Arabian Peninsula

The potentially catastrophic environmental consequences of the conflict in Iraq, Kuwait and Saudi Arabia, from mid 1990 to early 1991, have highlighted the need for background atmospheric chemistry measurements for the region. The only known cloudwater chemistry data obtained in the Arabian Peninsula are presented here. The samples were collected near the coast, in the Dhofar region of southern Oman, from 22 to 30 July 1990, immediately prior to the start of the conflict on 2 August. Analysis of the samples for pH, 10 major ion concentrations and 23 trace elements, demonstrates that the cloud water was very clean. Enrichment factor calculations showed the ions have oceanic and crusal origins, whereas trace elements such as B, V, Mn, Ni, Zn, Se, Sr, Mo and Ba have anthropogenic sources. In comparison with three mountain cloudwater sampling sites in eastern North America, the Omani site has higher pH values, higher Na+ and Cl− concentrations, and lower SO42− and NH4+ concentrations.

An alternative water supply for chilean coastal desert villages

The measured domestic water consumption rates in two fishing villages on the arid north coast of Chile were 14.2 and 19.7 l/pers/day. The villagers pay 10% of their family income for water in Chungungo and 6% in Los Hornos. The true subsidized cost of the water would represent 39% and 26% respectively of average family income. These high water costs led to the establishment of a project to determine if fog water collection could provide a lower cost water supply. The site, on the ridge above the village of Chungungo, has produced 7200 l/day, an average of 22 I/day for each of the 330 people in the village, during its first 32 months of operation, at a cost estimated to be one‐quarter of that of the current water supply. In addition, the fog water supply should be more reliable and of equal or better quality.

Measurements of the Properties of High Elevation Fog in Quebec, Canada

The Chemistry of High Elevation Fog (CHEF) programme is operational twelve months a year on two mountains (Mt. Tremblant and Roundtop Mtn.) in Quebec, Canada and for four months on a third mountain (Mt. Epaule), all having maximum elevations of 970 m. Measurements include: fog water chemistry, precipitation chemistry, ozone concentrations and meteorological observations. Field observations indicate that the summit of Roundtop Mtn. is in cloud about 44% of the time. The mountain (above 457 m) has an estimated forest exposure to acidic fog of 105 km2 h y-1, In autumn 1985 the daily median Roundtop summit fog pH was 3.8 (mean 3.7), and the median precipitation pH 4.55 (mean 4.3). At Mt. Tremblant the values were 3.9 (mean 3.8) and 4.3 (mean 4.25) respectively. In spring 1986 the daily median fog pH on Mt. Tremblant was 4.0 (mean 4.0) and the precipitation pH 4.5 (mean 4.4). The NO3 -/SO4 = equivalents ratios in the spring fog water and precipitation were in the 0.4 to 0.5 range with concentrations of NO3 - and SO4 = enhanced by a factor of 5 to 10 in the fog water.

Fog collection and its relationship with local meteorological variables in a semiarid zone in Chile

In semiarid and arid zones, fog is considered an important alternative water source. The Southeast Pacific anticyclone and the cold Humboldt Current that characterize the north of Chile promote the formation of stratocumulus along the coastline. The thermally induced winds move these clouds eastwards favoring the formation of fog in the high hills of the Coast Range. The goal of this work is to characterize the fog water collected by a standard fog collector and its relationship with local meteorological variables. We found that the collected water is seasonally dependent, larger in summer than in winter. The mean diurnal cycle in autumn, summer and winter presents two maxima, at the early morning and late afternoon, meanwhile in winter it presents smooth variations during the day. The wind regime was compatible with land-sea circulation. The monthly mean temperature reached the maximum value in March and the minimum value between July and September, whereas the mean monthly daily temperature amplitude was larger in winter than in summer. The minimum values of relative humidity were achieved in the winter months. The fog water collection varies from zero to a maximum value that increased with wind speed, and mainly occurred with SW and NE winds. The fog index (FI) was defined as the percentage of foggy-days per month for which the water collected is greater than one liter. We found that FI follows the same trend as the monthly collected water, and decreases with the mean monthly daily temperature amplitude.

Escenarios territoriales para la gestión preventiva de la desertificación en la cuenca del Puangue, Chile

This paper proposes territorial scenarios for decision making in order to prevent desertification processes in the Puangue basin, in the Metropolitan Region of the Santiago, Chile. The above is done through the implementation of a system of indicators of environmental dangerousness for desertification in a local scale. As a result, the identified territory in areas at risk to desertification and the projection is constructed with climate change, concluding on the need to generate action to prevent further desertification. This document becomes an approach to integrated local knowledge for the preventive management of the areas at risk to desertification.