An improved hemispherical photography model for stream surface shortwave radiation estimations in a central U.S. hardwood forest. Issue 26 (20th September 2012)

• Record Type: Journal Article
• Authors: Bulliner, Edward; Hubbart, Jason A.
• Is Part Of: Hydrological processes. Volume 27:Issue 26(2013:Dec. 30)
• Page Start: 3885
• Page End: 3895
• Publication Date: 2012-09-20
• Subjects: Hydrology -- Periodicals; Hydrology -- Research -- Periodicals; Hydrologic models -- Periodicals; Hydrological forecasting -- Periodicals; 631.432
• DOI: 10.1002/hyp.9524
• Languages: English
• ISSNs: 0885-6087

Abstract

<abstract abstract-type="main"> <title>Abstract</title> <p>Hemispherical photographs of forest canopies can be used to develop sophisticated models that predict incident below canopy shortwave radiation on the surface of interest (i.e. soil and water). Hemispherical photographs were collected on eight dates over the course of a growing season to estimate leaf area index and to quantify solar radiation incident on the surface of two stream reaches based on output from Gap Light Analyser and Hemisfer software. Stream reaches were shaded by a mixed‐deciduous Ozark border forested riparian canopy. Hemispherical photo model results were compared to observed solar radiation sensed at climate stations adjacent to each stream reach for the entire 2010 water year. Modeled stream‐incident shortwave radiation was validated with above‐stream pyranometers for the month of September. On average, the best hemispherical photo models underestimated daily averages of solar radiation by approximately 14% and 12% for E–W and N–S flowing stream reaches, respectively (44.7 W/m<sup>2</sup> measured <italic>vs</italic> 38.4 W/m<sup>2</sup> modeled E–W, 46.8 W/m<sup>2</sup> vs. 41.1 W/m<sup>2</sup>N–S). The best hemispherical photo models overestimated solar radiation relative to in–Stream pyranometers placed in the center of each stream reach by approximately 7% and 17% for E–W and N–S stream reaches respectively (31.3 W/m<sup>2</sup> measured <italic>vs</italic> 33.5 W/m<sup>2</sup> modeled E–W, 31.5 W/m<sup>2</sup> vs. 37.1 W/m<sup>2</sup>N–S). The model provides a geographically transferable means for quantifying changes in the solar radiation regime at a stream surface due to changes in canopy density through a growing season, thus providing a relatively simple method for estimating surface and water heating in canopy altered environments (e.g. forest harvest).</p> <p>Copyright © 2012 John Wiley & Sons, Ltd.</p> </abstract>