HDR-ASIS: A New Instrument for Investigation of Atmosphere-Radiation-Photosynthesis Relations and Carbon Dynamics in Terrestrial Ecosystems

Dennis G. Dye, U.S. Geological Survey, ddye@usgs.gov (Presenter)

Variability in diffuse solar radiation caused by clouds and atmospheric aerosols has been widely shown to be a major determinant of canopy-to-global scale rates of photosynthesis, atmospheric carbon-dioxide exchange, and photosynthetic light-use efficiency in terrestrial ecosystems. Research aimed at a deeper understanding of the diffuse radiation phenomenon, and reliable methods to account for it in detailed 3-D models of vegetation canopy radiative transfer and photosynthesis, have been constrained by the absence of a suitable sensor for measuring and monitoring the directional and spectral properties of diffuse radiation. A new ground-based remote sensing instrument, the High Dynamic Range All-Sky Imaging System (HDR-ASIS), was recently developed to provide this capability. HDR-ASIS combines an upward-looking, temperature-controlled digital camera with high-dynamic range imaging techniques to capture hemispherical, multispectral, radiometric images of the sky dome. The camera’s image sensor records sky radiance in red, green and blue spectral bands, including the direct-beam flux from the sun, without saturation and without a shadow-band device to occlude the solar disk. A field campaign to evaluate the performance of HDR-ASIS has been underway since May, 2011, and will conclude at the end of October, 2011. This poster describes the design and operation of HDR-ASIS, reports initial results from the field campaign, and suggests new opportunities for research and collaboration. Plans are discussed for using HDR-ASIS in a current NASA-sponsored study of the seasonal growth dynamics of tropical forest and savanna in Brazil, and in a new, proposed project to quantify radiation-related uncertainties in model estimates of ecosystem-atmosphere carbon exchange.

Presentation Type:  Poster

Session:  Coupled Processes at Land-Atmosphere-Ocean Interfaces   (Mon 4:00 PM)

Associated Project(s): 

• Related Activity

Poster Location ID: 17