Exploratory Continuous Multispectral Reflectance Measurements at Harvard Forest

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ABSTRACT/Moore The general objective of this research is to relate seasonal changes in narrow-band surface reflectance to evapotranspiration in mid-latitude deciduous forest. The specific objectives are: 1. To detect seasonal change in surface albedo (reflectance) in certain important wavebands, and link these changes to canopy liquid water content, 2. To relate reflectance measurements to surface turbulent energy fluxes, especially evapotranspiration, through the surface resistance to water vapor transfer, 3. To compare seasonal changes in narrow-band multispectral reflectance with satellite broadband reflectance (visible and near- infrared) in biweekly composites. 4. To use the aerosol optical depths retrieved from the upward-looking shadowband instrument to calculate atmospheric corrections for satellite data, according to published schemes. The overall goal of this study is to improve indirect measurements of surface energy and trace gas fluxes using surface- based remote sensing techniques. The investigator proposes to study seasonal changes in forest canopy reflectance and its relationship to surface turbulent energy exchange. Vegetation exerts a strong influence on regional climate through control of the surface fluxes of energy and trace gases, especially evapotranspiration. This proposed study is a logical development form a unique, ongoing long-term measurement program at Harvard Forest in Massachusetts; that study has yielded results indicating that certain seasonal changes in canopy radiative properties (near- infrared reflectance, thermal response) can be related to evapotranspiration. The investigator proposes to complement the ongoing turbulent energy flux and radiation measurement program at Harvard Forest with both upward-looking and downward-looking Multifilter Rotating Shadowband Radiometers.