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Quantitative Measures of Immersion in Cloud and the Biogeography of Cloud ForestsSites described as tropical montane cloud forests differ greatly, in part because observers tend to differ in their opinion as to what constitutes frequent and prolonged immersion in cloud. This definitional difficulty interferes with hydrologic analyses, assessments of environmental impacts on ecosystems, and biogeographical analyses of cloud forest communities and species. Quantitative measurements of cloud immersion can be obtained on site, but the observations are necessarily spatially limited, although well-placed observers can examine 10 50 km of a mountain range under rainless conditions. Regional analyses, however, require observations at a broader scale. This chapter discusses remote sensing and modeling approaches that can provide quantitative measures of the spatiotemporal patterns of cloud cover and cloud immersion in tropical mountain ranges. These approaches integrate remote sensing tools of various spatial resolutions and frequencies of observation, digital elevation models, regional atmospheric models, and ground-based observations to provide measures of cloud cover, cloud base height, and the intersection of cloud and terrain. This combined approach was applied to the Monteverde region of northern Costa Rica to illustrate how the proportion of time the forest is immersed in cloud may vary spatially and temporally. The observed spatial variation was largely due to patterns of airflow over the mountains. The temporal variation reflected the diurnal rise and fall of the orographic cloud base, which was influenced in turn by synoptic weather conditions, the seasonal movement of the Intertropical Convergence Zone and the north-easterly trade winds. Knowledge of the proportion of the time that sites are immersed in clouds should facilitate ecological comparisons and biogeographical analyses, as well as land use planning and hydrologic assessments in areas where intensive on-site work is not feasible.
Document ID
20110008651
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
Authors
Lawton, R. O.
(Alabama Univ. Huntsville, AL, United States)
Nair, U. S.
(Alabama Univ. Huntsville, AL, United States)
Ray, D.
(Purdue Univ. West Lafayette, IN, United States)
Regmi, A.
(Purdue Univ. West Lafayette, IN, United States)
Pounds, J. A.
(Monteverde Cloud Forest Reserve and Tropical Science Center San Jose, Costa Rica)
Welch, R. M.
(Alabama Univ. Huntsville, AL, United States)
Date Acquired
August 25, 2013
Publication Date
January 1, 2010
Publication Information
Publication: Tropical Montane Cloud Forests: Science for Conservation and Management
Volume: Chapter 22
Subject Category
Meteorology And Climatology
Funding Number(s)
CONTRACT_GRANT: NNX06AB68G
Distribution Limits
Public
Copyright
Other

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